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Sample records for antenna straps design

  1. Simulation Results for the New NSTX HHFW Antenna Straps Design by Using Microwave Studio

    SciTech Connect

    Kung, C C; Brunkhorst, C; Greenough, N; Fredd, E; Castano, A; Miller, D; D'Amico, G; Yager, R; Hosea, J; Wilson, J R; Ryan, P

    2009-05-26

    Experimental results have shown that the high harmonic fast wave (HHFW) at 30 MHz can provide substantial plasma heating and current drive for the NSTX spherical tokamak operation. However, the present antenna strap design rarely achieves the design goal of delivering the full transmitter capability of 6 MW to the plasma. In order to deliver more power to the plasma, a new antenna strap design and the associated coaxial line feeds are being constructed. This new antenna strap design features two feedthroughs to replace the old single feed-through design. In the design process, CST Microwave Studio has been used to simulate the entire new antenna strap structure including the enclosure and the Faraday shield. In this paper, the antenna strap model and the simulation results will be discussed in detail. The test results from the new antenna straps with their associated resonant loops will be presented as well.

  2. Rotated 4-strap ICRF antenna: design and initial results

    NASA Astrophysics Data System (ADS)

    Wukitch, S. J.; Beck, W.; Doody, J.; Garret, M.; Koert, P.; Lin, Y.; Vieira, R.; Terry, J.; The Alcator C-MOD Team

    2011-10-01

    Previously, we have utilized low Z thin films to mitigate impurities related to ion cyclotron range of frequency (ICRF) antenna operation. A new rotated antenna is has been designed and installed to minimize impurity production by imposing symmetry along the total magnetic field line. The antenna is aligned to a 10° field pitch where the typical discharge range is 7-13° in C-Mod. Compared to our standard antennas (0° pitch), the power density (MW/m2) for the rotated antenna is ~50% higher for a given injected power for the rotated antenna due a decrease in available surface area. Due to geometric limitations, two locations have the RF electric field aligned with the total magnetic field and have potential to limit the antenna voltage handling. Initial results from experiments characterizing the power and voltage limits of the antenna will be presented. Using the standard antennas as reference, we will also present results from comparison of antenna impurity characteristics and their impact on the scrape off layer transport. Supported by US DOE award DE-FC02-99ER54512.

  3. Structural Design of the ICRH Antenna's Straps of the Ignitor Experiment

    NASA Astrophysics Data System (ADS)

    Berruti, T.; Gola, M. M.; Salvetti, M. F.

    2002-11-01

    The ICRH antenna of the Ignitor experiment consists of an array of four poloidally-oriented straps, fed at one end and short circuited to the vacuum vessel at the other end. The feeders and the coaxial lines are located at the central part of the antenna because of the limited size of the equatorial ports. Both the assembly and the maintenance operations must be carried out in remote handling. Detailed non-linear thermo-structural analyses have been performed resorting to the ANSYS finite element code. A 3-D model of a single strap has been generated and thermal and electromagnetic loads have been applied to simulate normal and out-of-normal operating conditions. The Lorentz forces generated by eddy currents have been calculated and a resistive lumped circuit model has been considered in order to determine the currents, and the related forces, induced during a vertical displacement event. The design of the straps is optimized to facilitate remote handling operations and to minimize stresses at the connections. The results show that the straps will be able to withstand the expected loads during the considered operation conditions.

  4. Design and Analysis of the Alcator C-Mod Two-Strap ICRF Antenna

    NASA Astrophysics Data System (ADS)

    Takase, Y.; Golovator, S. N.; Porkolab, M.; Bajwa, K.; Becker, H.; Caldwell, D.

    1992-01-01

    ICRF fast wave heating with up to 8 MW of rf power at 80 MHz is planned on the Alcator C-MOD tokamak (R=0.665 m, a=0.21 m, κ=1.8, B≤9 T, I≤3 MA). During the initial tokamak operation, a movable single-strap antenna will be used to ensure operational flexibility. The second ICRF antenna, which is currently under construction, has two current straps which can be driven out-of-phase to improve the heating efficiency and minimize impurity generation. The current straps are mechanically isolated from the 4` feedthroughs. The Faraday shield consists of a single layer of circular cross section rods which are slanted at 10° to horizontal to approximately align with the field line over a wide range of operating conditions. The antenna box is protected by TiC coated TZM (Molybdenum alloy) tiles arranged in a ``picture-frame'' fashion. These tiles can be replaced with tiles made of a lower Z material. Because of its larger size, the two-strap antenna must be assembled inside the vacuum chamber and attached to the wall of the vacuum vessel to support against larger disruption loads. The rf thermal loads are significantly lower for the same total power (2 MW per antenna), which allows a longer pulse (10 sec) operation.

  5. First results with 3-strap ICRF antennas in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Bobkov, V.; Braun, F.; Dux, R.; Herrmann, A.; Faugel, H.; Fünfgelder, H.; Kallenbach, A.; Neu, R.; Noterdaeme, J.-M.; Ochoukov, R.; Pütterich, Th.; Tuccilo, A.; Tudisco, O.; Wang, Y.; Yang, Q.; ASDEX Upgrade Team

    2016-08-01

    The 3-strap antennas in ASDEX Upgrade allow ICRF operation with low tungsten (W) content in the confined plasma with W-coated antenna limiters. With the 3-strap antenna configuration, the local W impurity source at the antenna is drastically reduced and the core W concentration is similar to that of the boron coated 2-strap antenna at a given ICRF power. Operation of the 3-strap antennas with the power ratio between the central and the outer straps of 1.5:1 and 2:1 is adopted to minimize the ICRF-specific W release.

  6. Upgrades to the 4-strap ICRF Antenna in Alcator C-Mod

    SciTech Connect

    G. Schilling; J.C. Hosea; J.R. Wilson; W. Beck; R.L. Boivin; P.T. Bonoli; D. Gwinn; W.E. Lee; E. Nelson-Melby; M. Porkolab; R. Vieira; S.J. Wukitch; and J.A. Goetz

    2001-06-12

    A 4-strap ICRF antenna suitable for plasma heating and current drive has been designed and fabricated for the Alcator C-Mod tokamak. Initial operation in plasma was limited by high metallic impurity injection resulting from front surface arcing between protection tiles and from current straps to Faraday shields. Antenna modifications were made in February 2000, resulting in impurity reduction, but low-heating efficiency was observed when the antenna was operated in its 4-strap rather than a 2-strap configuration. Further modifications were made in July 2000, with the installation of BN plasma-facing tiles and radio- frequency bypassing of the antenna backplane edges and ends to reduce potential leakage coupling to plasma surface modes. Good heating efficiency was now observed in both heating configurations, but coupled power was limited to 2.5 MW in H-mode, 3 MW in L-mode, by plasma-wall interactions. Additional modifications were started in February 2001 and will be completed by this meeting. All the above upgrades and their effect on antenna performance will be presented.

  7. Theoretical analysis of the EAST 4-strap ion cyclotron range of frequency antenna with variational theory

    NASA Astrophysics Data System (ADS)

    Zhang, Jia-Hui; Zhang, Xin-Jun; Zhao, Yan-Ping; Qin, Cheng-Ming; Chen, Zhao; Yang, Lei; Wang, Jian-Hua

    2016-08-01

    A variational principle code which can calculate self-consistently currents on the conductors is used to assess the coupling characteristic of the EAST 4-strap ion cyclotron range of frequency (ICRF) antenna. Taking into account two layers of antenna conductors without lateral frame but with slab geometry, the antenna impedances as a function of frequency and the structure of RF field excited inside the plasma in various phasing cases are discussed in this paper. Project supported by the National Magnetic Confinement Fusion Science Program, China (Grant No. 2015GB101001) and the National Natural Science Foundation of China (Grant Nos. 11375236 and 11375235).

  8. Influence of mutual coupling between ICRH antenna straps on the load resilience of hybrid couplers

    SciTech Connect

    Lamalle, P. U.; Messiaen, A.

    2007-09-28

    The mutual coupling present between ICRF antenna straps can strongly reduce the performance of quadrature hybrid couplers when used as 'ELM dump' circuits. An analytical study of this effect shows that during resistive ELM-like load perturbations of a matched circuit configuration, the fraction of the reflected power returned to the generator through the hybrid has a lower bound that rapidly increases with the ratio {xi}{approx} (mutual reactance between straps)/(strap input resistance). At very low levels of mutual the reflected power is efficiently diverted to the dummy load. However when {xi} becomes of order 1, which readily occurs at low resistive loading, the load resilience of the quadrature hybrid coupler becomes inhibited. Illustrations based on matching circuit simulations for the JET ITER-like ICRF antenna are presented. The behaviour of the hybrids is found the same with the load resilient 'conjugate T' circuit as in the case of 'classic' tuners. The insertion of decoupling circuits between the tuners and the antenna significantly improves the load resilience.

  9. Measurements and simulations of ICRF induced plasma convection in front of the 3-strap antennas in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; ASDEX Upgrade Team; Eurofusion MST1 Team

    2016-10-01

    Plasma heating with waves in the Ion Cyclotron Range of Frequency (ICRF) is one of the standard heating methods in tokamaks. The parallel (to the magnetic field) component of the electric field of the waves enhances the edge plasma potential nonlinearly through radio-frequency-sheath (rf-sheath) rectification. The gradient of this potential across magnetic field drives plasma convection in the Scrape-Off Layer. To reduce the rf-sheath driven close to ICRF antennas, the parallel electric near-field has to be decreased. This can be achieved by minimization of undesired parasitic currents induced in the antenna box by the antenna currents. New antennas with a novel approach to reduce those undesired currents through the proper phase and amplitude of the current in 3-straps have been installed and validated on ASDEX Upgrade. With reflectometers embedded in one 3-strap antenna at different poloidal locations, the density profiles in front of the antenna can be measured in when the antenna is either active or passive. The ICRF induced edge plasma convection in different antenna feeding configurations (different phasing, different power ratio between the central and the side straps) has thus been studied. Also we have carried out comprehensive simulations by running the EMC3EIRENE, RAPLICASOL and SSWICH codes in an iterative and quasi self-consistent way. The steadystate ICRF induced plasma density convection can clearly be reproduced in the models and compared with the ones measured in experiments.

  10. Field-aligned ICRF antenna design for EAST

    NASA Astrophysics Data System (ADS)

    Wukitch, S. J.; Lin, Y.; Qin, C.; Zhang, X.; Beck, W.; Koert, P.; Zhou, L.

    2015-12-01

    For ion cyclotron range of frequency (ICRF), a number of physics and technological challenges remain for steady state, toroidal devices. Among the most critical is maintaining good coupling and maximizing the coupled power through plasma variations including edge localized modes (ELMs) and confinement transitions. As pulse length increases, enhanced localized heat loads associated with antenna operation can challenge antenna integrity. In addition, ICRF impurity sources and contamination need to be minimized to enable effective plasma heating. Here, we report on a four strap field aligned (FA) antenna design for the EAST tokamak. A FA antenna is an antenna where the current straps and antenna side enclosure are perpendicular to the total magnetic field while the Faraday screen rods are parallel to the total magnetic field. In C-Mod, a FA antenna has been shown to be inherently load tolerant which allows for robust power delivery to the plasma. Furthermore, the RF enhanced heat flux and antenna impurity source were nearly eliminated. For both L and H-mode discharges, the core impurity contamination is 20-30% lower but not eliminated. The emerging physics understanding is that the local RF impurity sources and RF enhanced heat flux is reduced due to the geometric alignment of the FA antenna while impurity contamination is a result of far field sheaths. An important aspect of antenna design is to identify a core absorption scenario that is characterized by strong single pass absorption for a broad range of target discharges. To maximize power coupling, the antenna spectrum needs to balance the k|| needed for strong single pass absorption and high coupling efficiency through evanescent layer. The latest design for a FA four strap adapted to EAST device is balance between geometrical constraints and physics requirements.

  11. Overview on Experiments On ITER-like Antenna On JET And ICRF Antenna Design For ITER

    SciTech Connect

    Nightingale, M. P. S.; Blackman, T.; Edwards, D.; Fanthome, J.; Graham, M.; Hamlyn-Harris, C.; Hancock, D.; Jacquet, P.; Mayoral, M.-L.; Monakhov, I.; Nicholls, K.; Stork, D.; Whitehurst, A.; Wilson, D.; Wooldridge, E.

    2009-11-26

    Following an overview of the ITER Ion Cyclotron Resonance Frequency (ICRF) system, the JET ITER-like antenna (ILA) will be described. The ILA was designed to test the following ITER issues: (a) reliable operation at power densities of order 8 MW/m{sup 2} at voltages up to 45 kV using a close-packed array of straps; (b) powering through ELMs using an internal (in-vacuum) conjugate-T junction; (c) protection from arcing in a conjugate-T configuration, using both existing and novel systems; and (d) resilience to disruption forces. ITER-relevant results have been achieved: operation at high coupled power density; control of the antenna matching elements in the presence of high inter-strap coupling, use of four conjugate-T systems (as would be used in ITER, should a conjugate-T approach be used); operation with RF voltages on the antenna structures up to 42 kV; achievement of ELM tolerance with a conjugate-T configuration by operating at 3{omega} real impedance at the conjugate-T point; and validation of arc detection systems on conjugate-T configurations in ELMy H-mode plasmas. The impact of these results on the predicted performance and design of the ITER antenna will be reviewed. In particular, the implications of the RF coupling measured on JET will be discussed.

  12. Three-Dimensional Electromagnetic Modeling of the ITER ICRF Antenna (External Matching Design)

    SciTech Connect

    Louche, F.; Lamalle, P.U.; Dumortier, P.; Messiaen, A.M.

    2005-09-26

    The present work reports on 3D radio-frequency (RF) analysis of a design for the ITER antenna with the CST Microwave Studio registered software. The four-port junctions which connect the straps in triplets have been analyzed. Non-TEM effects do not play any significant role in the relevant frequency domain, and a well-balanced splitting of current between the straps inside a triplet is achieved. The scattering matrix has also been compared with RF measurements on a scaled antenna mockup, and the agreement is very good. Electric field patterns along the system have been obtained, and the RF optimization of the feeding sections is under way.

  13. Modular antenna design study

    NASA Technical Reports Server (NTRS)

    Ribble, J. W.

    1981-01-01

    The mechanical design of a modular antenna concept was developed sufficiently to allow manufacture of a working demonstration model of a module, to predict mass properties, and to make performance estimates for antenna reflectors composed of these modules. The primary features of this concept are: (1) each module is an autonomous structural element which can be attached to adjacent modules through a three point connection; (2) the upper surface is a folding hexagonal truss plate mechanism which serves as the supporting structure for a reflective surface; and (3) the entire truss and surface can be folded into a cylindrical envelope in which all truss elements are essentially parallel. The kinematic studies and engineering demonstration model fully verified the deployment kinematics, stowing philosophy, and deployment sequencing for large antenna modules. It was established that such modules can be stowed in packages as small as 25 cm in diameter, using 1.27 cm diameter structural tubes. The development activity indicates that this deployable modular approach towards building large structures in space will support erection of 450 m apertures for operation up to 3 GHz with a single space shuttle flight.

  14. ADVANCED ANTENNA DESIGN TECHNIQUES

    DTIC Science & Technology

    SPACE VEHICLE EXPANDABLE PENCIL-BEAM ANTENNA CONCEPTS ARE PRESENTED. A PRELIMINARY SELECTION IS MADE OF SEVEN PENCIL-BEAM AND FAN-BEAM...TYPES HAVING THE GREATEST RANGE FROM TWELVE SPACE VEHICLE ANTENNA CONCEPTS.

  15. Design of a developmental dual fail operational redundant strapped down inertial measurement unit

    NASA Technical Reports Server (NTRS)

    Morrell, F. R.; Russell, J. G.

    1980-01-01

    An experimental redundant strap-down inertial measurement unit (RSDIMU) is being developed at NASA-Langley as a link to satisfy safety and reliability considerations in the integrated avionics concept. The unit consists of four two-degrees-of-freedom (TDOF) tuned-rotor gyros, and four TDOF pendulous accelerometers in a skewed and separable semi-octahedron array. The system will be used to examine failure detection and isolation techniques, redundancy management rules, and optimal threshold levels for various flight configurations. The major characteristics of the RSDIMU hardware and software design, and its use as a research tool are described.

  16. Design of the ICRH antenna for TPX

    SciTech Connect

    Fogelman, C.H.; Goranson, P.L.; Swain, D.W.

    1996-01-01

    A 6-MW ion cyclotron (IC) system for the Tokamak Physics Experiment (TPX) is in the preliminary design phase. In conjunction with the 3-MW Lower Hybrid system and the 8-MW neutral beam system, the IC system will provide heating and current-drive capabilities to explore advanced tokamak physics and long-pulse (1000 s) operation. The IC launcher consists of six nickel-plated current straps arranged toroidally in pairs behind three water-cooled Faraday shields. The Faraday shields can be independently mid remotely detached by cutting water lines at the back of the launcher and removing bolts at the front to free each shield. The antenna can be located at the +2 cm flux line and retracted 10 cm. Faraday shields are usually copper- or nickel-plated stainless steel or inconel. Titanium is the preferred material to minimize activation without greatly decreasing electrical resistivity and therefore increasing disruption loads. The IC antenna research and development programs have provided data that confirm the feasibility of B{sub 4}C-coated nickel-plated titanium alloy in the TPX environment.

  17. Design and implementation of interactive strap-down inertial navigation simulation system for UAV

    NASA Astrophysics Data System (ADS)

    Cheng, Chuan-qi; Cheng, Xiang; Hao, Xiang-yang; Zhao, Man-dan

    2016-01-01

    Strap-down inertial navigation system (SINS) is widely used in military field, to facilitate the study of SINS algorithms and various coupled navigation algorithms, a simulation system of SINS is designed. Based on modular design, with good portability and expansibility, the system consists of four independent modules: analysis module of motion state, trajectory simulator, IMU simulation module and SINS calculation module. With graphical interface, the system can control every motion state of the trajectory, which is convenient to generate various trajectories efficiently. Using rotation vector attitude algorithm to process simulation data, experiment results show that the attitude, velocity and position error is consistent with the theoretical value, which verifies the rationality of the simulation model and the availability of the simulation system.

  18. A Newly Designed Tennis Elbow Orthosis With a Traditional Tennis Elbow Strap in Patients With Lateral Epicondylitis

    PubMed Central

    Saremi, Hossein; Chamani, Vahid; Vahab-Kashani, Reza

    2016-01-01

    Background Lateral epicondylitis is a common cause of pain and upper limb dysfunction. The use of counterforce straps for treatment of lateral epicondylitis is widespread. This kind of orthosis can be modified to have a greater effect on relieving pain by reducing tension on the origin of the extensor pronator muscles. Objectives To determine the immediate effects of a newly designed orthosis on pain and grip strength in patients with lateral epicondylitis. Materials and Methods Twelve participants (six men and six women) were recruited (mean age = 41 ± 6.7 years) and evaluated for pain and grip strength in three sessions. A 48-hour break was taken between each session. The first session was without any orthosis, the second session was with the new modified tennis elbow orthosis, and the third session was with a conventional tennis elbow strap. Results Both counterforce straps were effective. However, significantly more improvement was observed in pain and grip strength after using the newly modified orthosis (P < 0.05). Conclusions The newly designed strap reduces pain more effectively and improves grip strength by causing greater localized pressure on two regions with different force applications (two component vectors versus one). PMID:28180116

  19. Coupling Of The JET ICRF Antennas In ELMy H-mode Plasmas With ITER Relevant Plasma-Straps Distance

    SciTech Connect

    Mayoral, M.-L.; Monakhov, I.; Jacquet, P.; Brix, M.; Graham, M.; Erents, K.; Korotkov, A.; Lomas, P.; Mailloux, J.; McDonald, D. C.; Stamp, M.; Walden, A.; Hobirk, J.; Ongena, J.

    2007-09-28

    In ITER, the requirement for the ICRF antenna is to deliver 20 MW in ELMy H-mode plasmas with an averaged antenna - plasma separatrix distance of 14 cm. Two major problems will have to be solved: the very fast change in antenna loading during ELMs and the decrease of the loading when the plasma is pushed far away from the antenna. JET has the capability to combine these conditions and for the first time, experiments were performed in ELMy H-mode at antenna--separatrix distance, referred as ROG, varied from 10 to 14 cm. When ROG was increased, the perturbation caused by ELMs was found to decrease significantly and the loading between ELMs was found to deteriorate to very low values. In order to compensate the latter unwanted effect, different levels of deuterium gas were injected in the edge either from the divertor, the midplane or the top of the tokamak. Using this technique, the loading was increased by up to a factor 6 and up to 8 MW of ICRF power were coupled.

  20. Conformal Antennas and Integrated Design Procedures

    DTIC Science & Technology

    2006-10-01

    Conformal Antennas and Integrated Design Procedures Mauro Bandinelli, Aldo Citriniti , Antonio Guidoni IDS Ingegneria Dei Sistemi SpA Via Livornese...UNCLASSIFIED/UNLIMITED Bandinelli, M.; Citriniti , A.; Guidoni, A. (2006) Conformal Antennas and Integrated Design Procedures. In Multifunctional

  1. Design Concepts For A Long Pulse Upgrade For The DIII-D Fast Wave Antenna Array

    SciTech Connect

    Ryan, Philip Michael; Baity Jr, F Wallace; Caughman, John B; Goulding, Richard Howell; Hosea, J.; Greenough, Nevell; Nagy, Alex; Pinsker, R.; Rasmussen, David A

    2009-01-01

    A goal in the 5-year plan for the fast wave program on DIII-D is to couple a total of 3.6 MW of RF power into a long pulse, H-mode plasma for central electron heating. The present short-pulse 285/300 antenna array would need to be replaced with one capable of at least 1.2 MW, 10 s operation at 60 MHz into an H-mode (low resistive loading) plasma condition. The primary design under consideration uses a poloidally-segmented strap (3 sections) for reduced strap voltage near the plasma/Faraday screen region. Internal capacitance makes the antenna structure self-resonant at 60 MHz, strongly reducing peak E-fields in the vacuum coax and feed throughs.

  2. Wireless link design using a patch antenna

    SciTech Connect

    Hall, E

    2000-08-11

    A wireless link was designed using a patch antenna. In the process, several different models were tested. Testing proved a patch antenna was a viable solution for building a wireless link within the design specifications. Also, this experimentation provided a basis for future patch antenna design.

  3. Design of an ICRH antenna for RF-plasma interaction studies

    NASA Astrophysics Data System (ADS)

    Caughman, J. B. O.; Ryan, P. M.; Bigelow, T. S.; Diem, S. J.; Goulding, R. H.; Rasmussen, D. A.

    2012-10-01

    The interaction between an ion cyclotron resonant heating antenna and the near-field plasma can lead to rectified (high voltage) sheath formation and subsequent material erosion. This issue will be studied by using a simple loop antenna operated on the Physics Integration eXperiment (PhIX) at ORNL, which is a linear plasma device that uses an ECH heated helicon plasma source to create a high-density plasma suitable for use in a plasma-material interaction test stand. The antenna consists of a single strap with a single-tier Faraday shield. The antenna is ˜one-quarter wavelength long at 50 MHz and grounded at one end, which will allow for strap voltages of >20 kV to be located near the plasma. The PhIX edge plasma near the antenna is similar to typical edge conditions, with ne˜1-2x10^18/m^3 and Te=5-10 eV, with a magnetic field of 0.1-0.2 Tesla. Several diagnostics will be used to characterize the near-field interaction, including Langmuir and capacitive probes, energy analyzers, Stark effect spectroscopy, and local/remote material erosion measurements. Details of the antenna design and initial characterization will be presented.

  4. Pyrolytic graphite film thermal straps: Characterization testing

    NASA Astrophysics Data System (ADS)

    McKinley, Ian M.; Smith, Colin H.; Ramsey, Perry G.; Rodriguez, Jose I.

    2016-12-01

    This paper reports on the experimentally-measured conductance, stiffness, and particulate contamination of pyrolytic graphite film thermal straps. This work was aimed at assessing the feasibility of replacing standard aluminum foil in thermal straps with graphite film, which is more conductive and lighter. Four different U-shaped straps with similar cross-sections and terminals were tested in the study. Three of the straps had a three-inch long flexible section. One of these was made from aluminum 1100 foil, and two were made from Pyrovo pyrolytic graphite film (PGF). One of the PGF straps was fabricated with an aluminized mylar blanket that was sealed at the terminals. The last strap was made from PGF, was blanketed, and was six inches long. The conductance of each strap was measured as a function of mean strap temperature ranging from 60 K to 300 K. The peak measured conductance of the three-inch PGF and aluminum straps were 1.0 W/K at 162 K and 0.28 W/K at 64 K, respectively. The conductance of all straps converged to around 0.3 W/K as the mean strap temperature approached 60 K. In addition, the peak conductance of the six-inch PGF strap was 0.83 W/K at 150 K. The fact that its peak conductance was near the conductance of the three-inch PGF strap indicated that the thermal resistance of the terminals in the PGF straps was significant. For a given temperature, the conductance varied by as much as 15% for two units of the same strap design. One of the straps was thermally cycled from 300 K to 60 K ten times. Its conductance was unchanged by the thermal cycling. Furthermore, one of the six-inch long PGF straps was subjected to random vibration. The random vibration spectrum was designed so that one terminal achieved a maximum displacement of ± 0.25 in. from its neutral position in three orthogonal axes while the other was held stationary. The conductance of this strap was unaffected by the random vibration test. The straps were also tested for the level of

  5. A new radiation stripline ICRF antenna design for EAST Tokamak

    SciTech Connect

    Qin, C. M.; Zhao, Y. P.; Wan, B. N.; Li, J.; Zhang, X. J.; Yang, Q. X.; Yuan, S.; Braun, F.; Notedame, J.-M.; Kasahara, H.; Collaboration: ICRF Team on EAST

    2014-02-12

    A new type of toroidal long Radiation Stripline Antenna (RSA) is presented, which can effectively improve antenna radiation, leading in reduction of max voltage on transmission line and decrease of the sensitivity to ELM's of the ICRF system at some frequencies. Based on the new concept, a 4-straps RSA is proposed for EAST device. Using 3-D computing simulator code (HFSS), RF current distribution, S-parameters and electromagnetic field distribution on and near the RSA ICRF antenna are analyzed and compared with present ICRF antenna on EAST.

  6. Microfluidic serpentine antennas with designed mechanical tunability.

    PubMed

    Huang, YongAn; Wang, Yezhou; Xiao, Lin; Liu, Huimin; Dong, Wentao; Yin, Zhouping

    2014-11-07

    This paper describes the design and characterization of microfluidic serpentine antennas with reversible stretchability and designed mechanical frequency modulation (FM). The microfluidic antennas are designed based on the Poisson's ratio of the elastomer in which the liquid alloy antenna is embedded, to controllably decrease, stabilize or increase its resonance frequency when being stretched. Finite element modelling was used in combination with experimental verification to investigate the effects of substrate dimensions and antenna aspect ratios on the FM sensitivity to uniaxial stretching. It could be designed within the range of -1.2 to 0.6 GHz per 100% stretch. When the aspect ratio of the serpentine antenna is between 1.0 and 1.5, the resonance frequency is stable under stretching, bending, and twisting. The presented microfluidic serpentine antenna design could be utilized in the field of wireless mobile communication for the design of wearable electronics, with a stable resonance frequency under dynamic applied strain up to 50%.

  7. Head Strap Double Fluid Level Device: An Innovative and User Friendly Design to Record Natural Head Position (NHP)

    PubMed Central

    Jose, Nidhin Philip; Shetty, Siddarth

    2015-01-01

    Head positions can be oriented in a standardized position when the patient stands upright and focusses his/her eyes into a point in infinity. This is the natural head position. This position offers the maximum reproducibility and correlates well with the clinical picture offered to the diagnostician. This article describes an innovative and user friendly method to record natural head position using the head strap double fluid level device, a design modified from the popular fluid level device by Showfety, Vig and Matteson. PMID:25738103

  8. Integrated reflector antenna design and analysis

    NASA Technical Reports Server (NTRS)

    Zimmerman, M. L.; Lee, S. W.; Ni, S.; Christensen, M.; Wang, Y. M.

    1993-01-01

    Reflector antenna design is a mature field and most aspects were studied. However, of that most previous work is distinguished by the fact that it is narrow in scope, analyzing only a particular problem under certain conditions. Methods of analysis of this type are not useful for working on real-life problems since they can not handle the many and various types of perturbations of basic antenna design. The idea of an integrated design and analysis is proposed. By broadening the scope of the analysis, it becomes possible to deal with the intricacies attendant with modem reflector antenna design problems. The concept of integrated reflector antenna design is put forward. A number of electromagnetic problems related to reflector antenna design are investigated. Some of these show how tools for reflector antenna design are created. In particular, a method for estimating spillover loss for open-ended waveguide feeds is examined. The problem of calculating and optimizing beam efficiency (an important figure of merit in radiometry applications) is also solved. Other chapters deal with applications of this general analysis. The wide angle scan abilities of reflector antennas is examined and a design is proposed for the ATDRSS triband reflector antenna. The development of a general phased-array pattern computation program is discussed and how the concept of integrated design can be extended to other types of antennas is shown. The conclusions are contained in the final chapter.

  9. Alcator C-Mod ICRF fast wave antenna design and analysis and expected plasma performance

    NASA Astrophysics Data System (ADS)

    Takase, Y.; Golovato, S.; Porkolab, M.; Becker, H.; Diatchenko, N.; Kochan, S.; McCoy, C.; Pierce, N.

    1989-07-01

    The design and analysis of the fast wave antenna to be used for ICRF heating experiments on the Alcator C-Mod tokamak are described. A movable single-strap low-field-side-launch loop antenna will be used during the initial operation period. Structural analysis against disruption and thermal analysis are performed. Optimized two-strap antennae with twice the surface area are planned for high-power heating experiments. Antenna-plasma coupling studies indicate a poor (<20%) single-pass ion absorption for D(3He), and a radiation resistance of ≳10Ω. Minority ions are not expected to be accelerated to very high energies under typical operating densities (Teff≲50 keV for n¯e≳3×1020m-3), and energetic ions should mainly slow down on ions. The transport of minority ions broadens the energetic minority ion and slowing down profiles and reduces Teff, but the effect is small for n¯e≳3×1020m-3.

  10. Baseline antenna design for space exploration initiative

    NASA Technical Reports Server (NTRS)

    Chen, Y. L.; Nasir, M. A.; Lee, S. W.; Zaman, Afroz

    1993-01-01

    A key element of the future NASA Space Exploration Initiative (SEI) mission is the lunar and Mars telecommunication system. This system will provide voice, image, and data transmission to monitor unmanned missions to conduct experiments, and to provide radiometric data for navigation. In the later half of 1991, a study was conducted on antennas for the Mars Exploration Communication. Six antenna configurations were examined: three reflector and three phased array. The conclusion was that due to wide-angle scan requirement, and multiple simultaneous tracking beams, phased arrays are more suitable. For most part, this report studies phased array antenna designs for two different applications for Space Exploration Initiative. It also studies one design for a tri-reflector type antenna. These antennas will be based on a Mars orbiting satellite.

  11. Automated Antenna Design with Evolutionary Algorithms

    NASA Technical Reports Server (NTRS)

    Hornby, Gregory S.; Globus, Al; Linden, Derek S.; Lohn, Jason D.

    2006-01-01

    Current methods of designing and optimizing antennas by hand are time and labor intensive, and limit complexity. Evolutionary design techniques can overcome these limitations by searching the design space and automatically finding effective solutions. In recent years, evolutionary algorithms have shown great promise in finding practical solutions in large, poorly understood design spaces. In particular, spacecraft antenna design has proven tractable to evolutionary design techniques. Researchers have been investigating evolutionary antenna design and optimization since the early 1990s, and the field has grown in recent years as computer speed has increased and electromagnetic simulators have improved. Two requirements-compliant antennas, one for ST5 and another for TDRS-C, have been automatically designed by evolutionary algorithms. The ST5 antenna is slated to fly this year, and a TDRS-C phased array element has been fabricated and tested. Such automated evolutionary design is enabled by medium-to-high quality simulators and fast modern computers to evaluate computer-generated designs. Evolutionary algorithms automate cut-and-try engineering, substituting automated search though millions of potential designs for intelligent search by engineers through a much smaller number of designs. For evolutionary design, the engineer chooses the evolutionary technique, parameters and the basic form of the antenna, e.g., single wire for ST5 and crossed-element Yagi for TDRS-C. Evolutionary algorithms then search for optimal configurations in the space defined by the engineer. NASA's Space Technology 5 (ST5) mission will launch three small spacecraft to test innovative concepts and technologies. Advanced evolutionary algorithms were used to automatically design antennas for ST5. The combination of wide beamwidth for a circularly-polarized wave and wide impedance bandwidth made for a challenging antenna design problem. From past experience in designing wire antennas, we chose to

  12. Conformal Antenna Array Design Handbook

    DTIC Science & Technology

    1981-09-01

    PLANAR ARRAY PHASE C LbP=IowITH CORRECT CONFORMAL ARRAY PHASE C NbPt NOe OF PhS&. SH-IFT UITSPII- NoP*.GT*1O CONRCLT PHASES ARE USED C TAP19PATTLRN...of Antenna Arrays, Radio Science , Vol. 3, May 1968, pp. 401-522. M. T. Ma, "Theory and Application of Antenna Arrays", Wiley, New York, 1974, Chapter

  13. MRF study. Part 2: Antenna design

    NASA Technical Reports Server (NTRS)

    1976-01-01

    An assessment of the practical feasibility of the design and construction of an antenna to meet the requirements of a conceptual radar system is studied. Both the subscale antenna, nominally 5 by 4 meters in dimensions, and the full scale antenna, taken as nominally 18 by 4 meters in size, were considered. The examination of feasibility was from electrical, mechanical, and thermal standpoints. Fundamental, electrical, microwave design questions applying to both the subscale and the full scale antennas were considered in greater detail than questions of mechanical configuration and thermal design. Layouts were made in the development of preliminary configurations, along with a deployment method, for the subscale antenna in conjunction with an antenna cluster for alternate arrangements of the three pallet configuration. Implementation of the array and support structure and attachment of the array to the support and thermal provision was considered. Results show that a microwave design of antennas that incorporate traveling wave arrays can be effected with the beam scanned to 45 degrees in elevation without occurrence of higher order beams.

  14. Design of the ITER ICRF Antenna

    SciTech Connect

    Hancock, D.; Nightingale, M.; Bamber, R.; Dalton, N.; Lister, J.; Porton, M.; Shannon, M.; Wilson, D.; Wooldridge, E.; Winkler, K.

    2011-12-23

    The CYCLE consortium has been designing the ITER ICRF antenna since March 2010, supported by an F4E grant. Following a brief introduction to the consortium, this paper: describes the present status and layout of the design; highlights the key mechanical engineering features; shows the expected impact of cooling and radiation issues on the design and outlines the need for future R and D to support the design process. A key design requirement is the need for the mechanical design and analysis to be consistent with all requirements following from the RF physics and antenna layout optimisation. As such, this paper complements that of Durodie et al.

  15. Study of wrap-rib antenna design

    NASA Technical Reports Server (NTRS)

    Wade, W. D.; Sinha, A.; Singh, R.

    1979-01-01

    The results of a parametric design study conducted to develop the significant characteristics and technology limitations of space deployable antenna systems with aperture sizes ranging from 50 up to 300 m and F/D ratios between 0.5 and 3.0 are presented. Wrap/rib type reflectors of both the prime and offset fed geometry and associated feed support structures were considered. The significant constraints investigated as limitations on achievable aperture were inherent manufacturability, orbit dynamic and thermal stability, antenna weight, and antenna stowed volume. A data base, resulting in the defined maximum achievable aperture size as a function of diameter, frequency and estimated cost, was formed.

  16. 47 CFR 17.9 - Designated antenna farm areas.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Designated antenna farm areas. 17.9 Section 17... ANTENNA STRUCTURES Federal Aviation Administration Notification Criteria § 17.9 Designated antenna farm areas. The areas described in the following paragraphs of this section are established as antenna...

  17. 47 CFR 17.9 - Designated antenna farm areas.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Designated antenna farm areas. 17.9 Section 17... ANTENNA STRUCTURES Federal Aviation Administration Notification Criteria § 17.9 Designated antenna farm areas. The areas described in the following paragraphs of this section are established as antenna...

  18. 47 CFR 17.9 - Designated antenna farm areas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Designated antenna farm areas. 17.9 Section 17... ANTENNA STRUCTURES Federal Aviation Administration Notification Criteria § 17.9 Designated antenna farm areas. The areas described in the following paragraphs of this section are established as antenna...

  19. 47 CFR 17.9 - Designated antenna farm areas.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Designated antenna farm areas. 17.9 Section 17... ANTENNA STRUCTURES Federal Aviation Administration Notification Criteria § 17.9 Designated antenna farm areas. The areas described in the following paragraphs of this section are established as antenna...

  20. 47 CFR 17.9 - Designated antenna farm areas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Designated antenna farm areas. 17.9 Section 17... ANTENNA STRUCTURES Federal Aviation Administration Notification Criteria § 17.9 Designated antenna farm areas. The areas described in the following paragraphs of this section are established as antenna...

  1. Microwave Antennas: Design. (Latest citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning the design of microwave antennas. Topics include a discussion of the recent developments in microwave antennas, and in design techniques such as computer-aided design (CAD). Various types of antenna configurations are covered, including rectangular, elliptical, and reflectarray microstrip antennas, multibeam, circular-disc, Yagi-Uda, and horn reflectors. Applications include microwave antennas for satellite communication systems, telemetry links, and solid state microwave power transmission systems.

  2. Efficient Thermally Conductive Strap Design for Cryogenic Propellant Tank Supports and Plumbing

    NASA Technical Reports Server (NTRS)

    Elchert, J. P.; Christie, R.; Kashani, A.; Opalach, C.

    2012-01-01

    After evaluating NASA space architecture goals, the Office of Chief Technologist identified the need for developing enabling technology for long term loiters in space with cryogenic fluids. One such technology is structural heat interception. In this prototype, heat interception at the tank support strut was accomplished using a thermally conductive link to the broad area cooled shield. The design methodology for both locating the heat intercept and predicting the reduction in boil-off heat leak is discussed in detail. Results from the chosen design are presented. It was found that contact resistance resulting from different mechanical attachment techniques played a significant role in the form and functionality of a successful design.

  3. Efficient Thermally Conductive Strap Design for Cryogenic Propellant Tank Supports and Plumbing

    NASA Technical Reports Server (NTRS)

    Elchert, J. P.; Christie, R.; Gebby, P.; Kashani, A.

    2012-01-01

    After evalu1ating NASA space architecture goals, the Office of Chief Technologist identified the need for developing enabling technology for long term loiters in space with cryogenic fluids. One such technology is structural heat interception. In this prototype, heat interception at the tank support strut was accomplished using a thermally conductive link to the broad area cooled shield. The design methodology for both locating the heat intercept and predicting the reduction in boil-off heat leak is discussed in detail. Results from the chosen design are presented. It was found that contact resistance resulting from different mechanical attachment techniques played a significant role in the form and functionality of a successful design.

  4. FORTE antenna element and release mechanism design

    SciTech Connect

    Rohweller, D.J.; Butler, T.Af.

    1995-02-01

    The Fast On-Orbit Recording of Transient Events (FORTE) satellite being built by Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) has as its most prominent feature a large deployable (11 m by 5 m) log periodic antenna to monitor emissions from electrical storms on the Earth. This paper describes the antenna and the design for the long elements and explains the dynamics of their deployment and the damping system employed. It also describes the unique paraffin-actuated reusable tie-down and release mechanism employed in the system.

  5. FORTE antenna element and release mechanism design

    NASA Technical Reports Server (NTRS)

    Rohweller, David J.; Butler, Thomas A.

    1995-01-01

    The Fast On-Orbit Recording of Transient Events (FORTE) satellite being built by Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) has as its most prominent feature a large deployable (11 m by 5 m) log periodic antenna to monitor emissions from electrical storms on the Earth. This paper describes the antenna and the design for the long elements and explains the dynamics of their deployment and the damping system employed. It also describes the unique paraffin-actuated reusable tie-down and release mechanism employed in the system.

  6. Some aspects of the aerodynamics of separating strap-ons

    NASA Astrophysics Data System (ADS)

    Biswas, K. K.; Krishnan, C. G.

    1994-11-01

    An aerodynamics model for analyzing strap-on separation is proposed. This model comprises both interference aerodynamics and free-body aerodynamics. The interference aerodynamics is primarily due to the close proximity of core and strap-ons. The free-body aerodynamics is solely due to the body geometry of the strap-ons. Using this aerodynamic model, the dynamics of separating strap-ons has been simulated in a six-degree-of-freedom mode to determine if a collision occurs. This aerodynamic model is very handy for various off-design studies relating to separating strap-ons.

  7. Hemispherical radiating pattern antenna design for radio meteor observation

    NASA Astrophysics Data System (ADS)

    Kákona, J.

    2016-01-01

    A highly directional pattern antenna is usually used for radio meteor observations, but these types of antennas became impractical in cases where we have multiple transmitters spread around a reception station. In that situation the hemispherical sensitivity of the antenna is more important than directional antenna gain. We present a hemispherical radiation pattern antenna design which could be modified for almost any observational frequency reflective by a meteor trail. The symmetry of the radiation pattern of such antenna allows an easy construction of antenna arrays which could be used for the angular measurement of received signals.

  8. Computer program aids dual reflector antenna system design

    NASA Technical Reports Server (NTRS)

    Firnett, P.; Gerritsen, R.; Jarvie, P.; Ludwig, A.

    1968-01-01

    Computer program aids in the design of maximum efficiency dual reflector antenna systems. It designs a shaped cassegrainian antenna which has nearly 100 percent efficiency, and accepts input parameters specifying an existing conventional antenna and produces as output the modifications necessary to conform to a shaped design.

  9. Design concepts for large reflector antenna structures

    NASA Technical Reports Server (NTRS)

    Hedgepeth, J. M.; Adams, L. R.

    1983-01-01

    Practical approaches for establishing large, precise antenna reflectors in space are described. Reflector surfaces consisting of either solid panels or knitted mesh are considered. The approach using a deep articulated truss structure to support a mesh reflector is selected for detailed investigations. A new sequential deployment concept for the tetrahedral truss is explained. Good joint design is discussed, and examples are described both analytically and by means of demonstration models. The influence of curvature on the design and its vibration characteristics are investigated.

  10. Deployable antenna kinematics using tensegrity structure design

    NASA Astrophysics Data System (ADS)

    Knight, Byron Franklin

    With vast changes in spacecraft development over the last decade, a new, cheaper approach was needed for deployable kinematic systems such as parabolic antenna reflectors. Historically, these mesh-surface reflectors have resembled folded umbrellas, with incremental redesigns utilized to save packaging size. These systems are typically over-constrained designs, the assumption being that high reliability necessary for space operations requires this level of conservatism. But with the rapid commercialization of space, smaller launch platforms and satellite buses have demanded much higher efficiency from all space equipment than can be achieved through this incremental approach. This work applies an approach called tensegrity to deployable antenna development. Kenneth Snelson, a student of R. Buckminster Fuller, invented Tensegrity structures in 1948. Such structures use a minimum number of compression members (struts); stability is maintain using tension members (ties). The novelty introduced in this work is that the ties are elastic, allowing the struts to extend or contract, and in this way changing the surface of the antenna. Previously, the University of Florida developed an approach to quantify the stability and motion of parallel manipulators. This approach was applied to deployable, tensegrity, antenna structures. Based on the kinematic analyses for the 3-3 (octahedron) and 4-4 (square anti-prism) structures, the 6-6 (hexagonal anti-prism) analysis was completed which establishes usable structural parameters. The primary objective for this work was to prove the stability of this class of deployable structures, and their potential application to space structures. The secondary objective is to define special motions for tensegrity antennas, to meet the subsystem design requirements, such as addressing multiple antenna-feed locations. This work combines the historical experiences of the artist (Snelson), the mathematician (Ball), and the space systems engineer

  11. Second-generation zone plate antenna design

    NASA Astrophysics Data System (ADS)

    Wiltse, James C.

    1999-11-01

    A well-designed phase correcting Fresnel zone plate antenna can provide performance superior to a lens or, in some cases, a paraboloid antenna, particularly at millimeter wavelengths. This paper discusses design considerations and includes approaches to give improved characteristics, such as greater efficiency or higher gain. The approaches include the use of quarter-wave or better correction, thickness designs that permit the central zone and other zones to be air dielectric (for lower losses), and the use of low dielectric constant materials to reduce surface reflections and multiple reflections. At higher millimeter-wave or sub- millimeter wavelengths low loss materials are important. More sophisticated zoning is described, as well as the use of a compromise thickness to compensate for the fact that refraction of waves at the surfaces causes the path lengths through the zone plate to be different at different angles of incidence. Multiple-band zone plates are discussed.

  12. Adaptive optical antennas: design and evaluation

    NASA Astrophysics Data System (ADS)

    Weyrauch, Thomas; Vorontsov, Mikhail A.; Carhart, Gary W.; Simonova, Galina V.; Beresnev, Leonid A.; Polnau, Ernst E.

    2007-09-01

    We present the design and evaluation of compact adaptive optical antennas with apertures diameters of 16 mm and 100 mm for 5Gbit/s-class free-space optical communication systems. The antennas provide a bi-directional optically transparent link between fiber-optical wavelength-division multiplex systems and allow for mitigation of atmospheric-turbulence induced wavefront phase distortions with adaptive optics components. Beam steering is implemented in the antennas either with mirrors on novel tip/tilt platforms or a fiber-tip positioning system, both enabling operation bandwidths of more than 1 kHz. Bimorph piezoelectric actuated deformable mirrors are used for low-order phase-distortion compensation. An imaging system is integrated in the antennas for coarse pointing and tracking. Beam steering and wavefront control is based on blind maximization of the received signal level using a stochastic parallel gradient descent algorithm. The adaptive optics control architecture allowed the use of feedback signals provided locally within each transceiver system and remotely by the opposite transceiver system via an RF link. First atmospheric compensation results from communication experiments over a 250 m near-ground propagation path are presented.

  13. Millimeter-wave antenna design

    NASA Technical Reports Server (NTRS)

    Leighton, R. B.

    1977-01-01

    Problems and opportunities are discussed for adapting certain design features and construction techniques, developed for producing high accuracy ground based radio dishes, to producing milimeter wave dishes for space use. Specifically considered is a foldable telescope of 24 m aperture and 9.6 m focal length, composed of 37 rigid hexagonal panels, which will fit within the 4.5 m diameter x 18 m long payload limits of space shuttle. As here conceived, the telescope would be a free flyer with its own power and pointing systems. Some of the structural design features and construction procedures are considered.

  14. Evolutionary design of corrugated horn antennas

    NASA Technical Reports Server (NTRS)

    Hoorfar, F.; Manshadi, V.; Jamnejad, A.

    2002-01-01

    An evolutionary progranirnitzg (EP) algorithm is used to optimize pattern of a corrugated circularhorn subject to various constraints on return loss and antenna beamwidth and pattern circularity and low crosspolarization. The EP algorithm uses a Gaussian mutation operator. Examples on design synthesis of a 45 section corrugated horn, with a total of 90 optimization parameters, are presented. The results show excellent and efficient optimization of the desired horn parameters.

  15. Evolutionary design of corrugated horn antennas

    NASA Technical Reports Server (NTRS)

    Hoorfar, F.; Manshadi, V.; Jamnejad, A.

    2002-01-01

    An evolutionary progranirnitzg (EP) algorithm is used to optimize pattern of a corrugated circularhorn subject to various constraints on return loss and antenna beamwidth and pattern circularity and low crosspolarization. The EP algorithm uses a Gaussian mutation operator. Examples on design synthesis of a 45 section corrugated horn, with a total of 90 optimization parameters, are presented. The results show excellent and efficient optimization of the desired horn parameters.

  16. Designs for the ATDRSS tri-band reflector antenna

    NASA Technical Reports Server (NTRS)

    Lee, Shung-Wu; Zimmerman, Martin L.; Fujikawa, Gene; Sharp, G. Richard

    1991-01-01

    Two approaches to design a tri-band reflector antenna for the Advanced TDRSS are examined. Two reflector antenna configurations utilizing frequency selective surfaces for operation in three frequency bands, S, Ku, and Ka, are proposed. Far-field patterns and the antenna feed losses were computed for each configuration. An offset-fed single reflector antenna configuration was adapted for conceptual spacecraft design. CADAM drawings were completed and a 1/13th scale model of the spacecraft was constructed.

  17. Satellite antenna layout and optimization in electromagnetic compatibility design

    NASA Astrophysics Data System (ADS)

    Zhang, Jinshuo; Xie, Shuguo; Liu, Yan

    2009-12-01

    This paper firstly analyzes the main factors that impact the layout of satellite antenna. The uniform geometrical theory of diffraction (UTD) is used to establish mathematical model for calculating the coupling of satellite antenna, and set up the objective function of the placement optimization. The genetic algorithm incorporating high-frequency simulation to minimize antenna coupling by optimally positioning satellite antenna is described in detail. The results of antenna placement on a realistic satellite show that this method is effective in the optimal design of satellite antenna layout for the purpose of electromagnetic compatibility.

  18. Electromechanical co-design and experiment of structurally integrated antenna

    NASA Astrophysics Data System (ADS)

    Zhou, Jinzhu; Huang, Jin; Song, Liwei; Zhang, Dan; Ma, Yunchao

    2015-03-01

    This paper proposes an electromechanical co-design method of a structurally integrated antenna to simultaneously meet mechanical and electrical requirements. The method consists of three stages. The first stage involves finishing an initial design of the microstrip antenna without a facesheet or honeycomb, according to some predefined performances. Subsequently, the facesheet and honeycomb of the structurally integrated antenna are designed using an electromechanical co-design optimization. Based on the results from the first and second stages, a fine full-wave electromagnetic model is developed and the coarse design results are further optimized to meet the electrical performance. The co-design method is applied to the design of a 2.5 GHz structurally integrated antenna, and then the designed antenna is fabricated. Experiments from the mechanical and electrical performances are conducted, and the results confirm the effectiveness of the co-design method. This method shows great promise for the multidisciplinary design of a structurally integrated antenna.

  19. Stockpile reliability program for special purpose strap. Technical report

    SciTech Connect

    Mayfield, N.A.

    1993-06-01

    Since 1962, web strap tie-down assemblies have been used to secure nuclear weapon containers on tactical vehicles. In 1968, a 36 month useful life (in use) requirement was placed on the straps used to secure war reserve nuclear weapons containers on vehicles. This means that no matter what condition the straps were in, after 36 months they could no longer be used. Due to the numerous problems with the straps for different reasons throughout the years, in 1986 the US Army Armament Research, Development and Engineering Center was tasked to design a new special purpose strap. The US Armament, Munition and Chemical Command, Rock Island, was assigned to be the item manager and to procure the new design straps. Also, at that time, it was agreed that instead of placing the 36 month useful life requirement on the new straps, a stockpile reliability program would be established. This program was to determine whether real usage of tie-down strap could justify either the establishment of a 36 month useful life requirement or have no requirement at all and reject straps based on their condition as determined by inspections only. This report reflects the results, conclusions, and recommendations based on a 5 year stockpile reliability program.... Web strap tie-down assemblies, Stockpile Reliability Program(SPR), In-field use environment, Control storage sample, Base line, Ultimate load, Failure.

  20. Design and Analysis of Embedded Antennas for 60-mm Mortars

    DTIC Science & Technology

    2008-06-01

    antenna patches were fabricated from RT Duroid high-frequency laminate (RT6010) in the form of circular microstrip patches. This material is well...Weld) was used as a radome covering on each of the four antenna elements (figure 1 shows installed antenna elements and radome). A miniature ...alternative for embedded, high-g telemetry antenna designs. 7 3. References 1. Flowmerics, Inc. Microstripes . http://www.cst.com/ microstripes

  1. Design and layout of rectangular waveguide horns antennas

    NASA Astrophysics Data System (ADS)

    Fasold, D.; Pecher, H.

    Theoretical basis of waveguide horn antennas (WHA) is outlined. Applicable design curves, such as nomograms for determining gain and a diagram for laying out necessary waveguide dimensions, are given. Use of WHA designs in satellite radio and television systems is discussed. Antenna radiation pattern calculations are treated and optimization problems are dealt with. Based on design feasibility results, a laboratory model of a transmitter antenna for TV-SAT was built. The equipment, an elliptical waveguide horn design, demonstrates satisfactory performance.

  2. Adaptive antenna arrays for satellite communications: Design and testing

    NASA Technical Reports Server (NTRS)

    Gupta, I. J.; Swarner, W. G.; Walton, E. K.

    1985-01-01

    When two separate antennas are used with each feedback loop to decorrelate noise, the antennas should be located such that the phase of the interfering signal in the two antennas is the same while the noise in them is uncorrelated. Thus, the antenna patterns and spatial distribution of the auxiliary antennas are quite important and should be carefully selected. The selection and spatial distribution of auxiliary elements is discussed when the main antenna is a center fed reflector antenna. It is shown that offset feeds of the reflector antenna can be used as auxiliary elements of an adaptive array to suppress weak interfering signals. An experimental system is designed to verify the theoretical analysis. The details of the experimental systems are presented.

  3. Highly Directive Reflect Array Antenna Design for Wireless Power Transfer

    DTIC Science & Technology

    2017-04-14

    AFRL-AFOSR-JP-TR-2017-0033 Highly Directive Reflect Array Antenna Design for Wireless Power Transfer Siddhartha Prakash Duttagupta INDIAN INSTITUTE...Directive Reflect Array Antenna Design for Wireless Power Transfer 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-14-1-4076 5c.  PROGRAM ELEMENT NUMBER...Antenna Design for Wireless Power Principal Investigator: SP Duttagupta Email: sdgupta@ee.iitb.ac.in Institution: Indian Institute of Technology

  4. An Optimal Design For Steerable Dish Antenna With BWG

    NASA Technical Reports Server (NTRS)

    Chuang, K. L.; Lansing, F. L.

    1990-01-01

    New design proposed for highly-efficient 34-m-diameter millimeter-wavelength antennas of NASA's Deep Space Network. Incorporates axial beam waveguide, BWG, and improved structure to maintain shape and alignment of reflecting surfaces. General approach to conceptual construction of structure to modularize overall system so critical constraint conditions pertaining to microwave optics and structural performance satisfied. Design retrofitted to existing NASA Deep Space Network 34-m antennas, or used as basis to build large ground-based steerable antennas. Engineering concepts involved in design adapted to design of other large, steerable antennas for telecommunications, radio astronomy, and military uses.

  5. Biologically inspired coupled antenna beampattern design.

    PubMed

    Akçakaya, Murat; Nehorai, Arye

    2010-12-01

    We propose to design a small-size transmission-coupled antenna array, and corresponding radiation pattern, having high performance inspired by the female Ormia ochracea's coupled ears. For reproduction purposes, the female Ormia is able to locate male crickets' call accurately despite the small distance between its ears compared with the incoming wavelength. This phenomenon has been explained by the mechanical coupling between the Ormia's ears, which has been modeled by a pair of differential equations. In this paper, we first solve these differential equations governing the Ormia ochracea's ear response, and convert the response to the pre-specified radio frequencies. We then apply the converted response of the biological coupling in the array factor of a uniform linear array composed of finite-length dipole antennas, and also include the undesired electromagnetic coupling due to the proximity of the elements. Moreover, we propose an algorithm to optimally choose the biologically inspired coupling for maximum array performance. In our numerical examples, we compute the radiation intensity of the designed system for binomial and uniform ordinary end-fire arrays, and demonstrate the improvement in the half-power beamwidth, sidelobe suppression and directivity of the radiation pattern due to the biologically inspired coupling.

  6. Evolutionary Design of a Phased Array Antenna Element

    NASA Technical Reports Server (NTRS)

    Globus, Al; Linden, Derek; Lohn, Jason

    2006-01-01

    We present an evolved S-band phased array antenna element design that meets the requirements of NASA's TDRS-C communications satellite scheduled for launch early next decade. The original specification called for two types of elements, one for receive only and one for transmit/receive. We were able to evolve a single element design that meets both specifications thereby simplifying the antenna and reducing testing and integration costs. The highest performance antenna found using a genetic algorithm and stochastic hill-climbing has been fabricated and tested. Laboratory results are largely consistent with simulation. Researchers have been investigating evolutionary antenna design and optimization since the early 1990s, and the field has grown in recent years its computer speed has increased and electromagnetic simulators have improved. Many antenna types have been investigated, including wire antennas, antenna arrays and quadrifilar helical antennas. In particular, our laboratory evolved a wire antenna design for NASA's Space Technology 5 (ST5) spacecraft. This antenna has been fabricated, tested, and is scheduled for launch on the three spacecraft in 2006.

  7. Zeroth order resonator (ZOR) based RFID antenna design

    NASA Astrophysics Data System (ADS)

    Masud, Muhammad Mubeen

    Meander-line and multi-layer antennas have been used extensively to design compact UHF radio frequency identification (RFID) tags; however the overall size reduction of meander-line antennas is limited by the amount of parasitic inductance that can be introduced by each meander-line segment, and multi-layer antennas can be too costly. In this study, a new compact antenna topology for passive UHF RFID tags based on zeroth order resonant (ZOR) design techniques is presented. The antenna consists of lossy coplanar conductors and either inter-connected inter-digital capacitor (IDC) or shunt inductor unit-cells with a ZOR frequency near the operating frequency of the antenna. Setting the ZOR frequency near the operating frequency is a key component in the design process because the unit-cells chosen for the design are inductive at the operating frequency. This makes the unit-cells very useful for antenna miniaturization. These new designs in this work have several benefits: the coplanar layout can be printed on a single layer, matching inductive loops that reduce antenna efficiency are not required and ZOR analysis can be used for the design. Finally, for validation, prototype antennas are designed, fabricated and tested.

  8. Design and Evaluation of Compact Antennae for Ionospheric Sounding

    NASA Astrophysics Data System (ADS)

    Erjavec, T. J.; Vierinen, J.

    2014-12-01

    Compact high frequency (HF) antennas are crucial for enabling the use of HF radar sounding for ionospheric remote sensing using a dense network of sounders. Current ionosonde antennas are large and expensive. In this study, we investigate two compact HF antenna designs through modeling and prototypes: a folded resistively loaded dipole, and a capacitively tuned small magnetic loop. Both antennas were modeled using FEKO to investigate antenna efficiency and beam patterns. The folded dipole was bought off the shelf, while the compact magnetic loop prototype was built in house. In this study, we present both modeling and measurements of the antenna characteristics. We also present the first ionospheric soundings obtained using the prototype antennas.

  9. Design of Frequency Tunable Compact Antenna and Millimeter to Terahertz Array Antennas

    NASA Astrophysics Data System (ADS)

    Damman, Rafid Noel

    As increased bandwidth demands continue to rise and overly crowded existing bands need be relieved, the study of frequency tunable and higher frequency array antennas is needed. By tuning the resonant frequency of an antenna, the bandwidth increases since the operating frequency has increased from the tuning. Also, higher frequency antenna designs are beginning to take flight to alleviate the lower bands and allow for an increase in bandwidth. Both the methods can bring a solution to the increased bandwidth demand. Thesis work begins with the design of a novel single feed planar antenna with 4G tunable bands and consistent upper LTE bands. This antenna is simulated using full wave analysis tool, fabricated and measured. This antenna shows near omni-directional radiation pattern exhibiting gain levels from -4.25dBi in the lower band to 2.69dBi in the upper band. The impedance matching for the lower band can be tuned from 690 MHz - 970 MHz while the higher band is consistently present between 1.29 GHz - 2.05 GHz, both based on S 11 ≤ - 6dBi. To begin the stepping stone for higher frequency planar array antenna designs, first an 8x8 array antenna is designed in the Ka band. The impedance matching for this design is measured 28.34 GHz - 32.09 GHz having fractional bandwidth of 12.41% based on S11 ? - 10dB. This array antenna was fabricated and experimentally verified for its impedance matching and radiation performances. Next, a 4x4 antenna array is designed for operation in the 5G wireless band and using 0.07mm quartz material. The design has matching band from 53.6 GHz - 54.0 GHz having fractional bandwidth of 0.7435% based on S 11 ≤ -10dB. Finally, a 2x2 array antenna having a center frequency of 300 GHz with fractional bandwidth of 11.2% based on S11 ≤ -10dB is designed. This 2x2 array antenna was also designed using 0.07mm thick quartz substrate material so as to fabricate using the photolithography method due to the limitations of the standard method of

  10. Progress in integrated-circuit horn antennas for receiver applications. Part 1: Antenna design

    NASA Technical Reports Server (NTRS)

    Eleftheriades, George V.; Ali-Ahmad, Walid Y.; Rebeiz, Gabriel M.

    1992-01-01

    The purpose of this work is to present a systematic method for the design of multimode quasi-integrated horn antennas. The design methodology is based on the Gaussian beam approach and the structures are optimized for achieving maximum fundamental Gaussian coupling efficiency. For this purpose, a hybrid technique is employed in which the integrated part of the antennas is treated using full-wave analysis, whereas the machined part is treated using an approximate method. This results in a simple and efficient design process. The developed design procedure has been applied for the design of a 20, a 23, and a 25 dB quasi-integrated horn antennas, all with a Gaussian coupling efficiency exceeding 97 percent. The designed antennas have been tested and characterized using both full-wave analysis and 90 GHz/370 GHz measurements.

  11. Design and verification of mechanisms for a large foldable antenna

    NASA Technical Reports Server (NTRS)

    Luhmann, Hans Jurgen; Etzler, Carl Christian; Wagner, Rudolf

    1989-01-01

    The characteristics of the Synthetic Aperture Radar (SAR) antenna aboard the ESA Remote Sensing Satellite (ERS-1) are presented. The antenna is folded into a dense package for launch and is deployed in orbit. The design requirements and constraints, their impact on the design, and the resulting features of the mechanisms are discussed.

  12. Modern Design of Resonant Edge-Slot Array Antennas

    NASA Technical Reports Server (NTRS)

    Gosselin, R. B.

    2006-01-01

    Resonant edge-slot (slotted-waveguide) array antennas can now be designed very accurately following a modern computational approach like that followed for some other microwave components. This modern approach makes it possible to design superior antennas at lower cost than was previously possible. Heretofore, the physical and engineering knowledge of resonant edge-slot array antennas had remained immature since they were introduced during World War II. This is because despite their mechanical simplicity, high reliability, and potential for operation with high efficiency, the electromagnetic behavior of resonant edge-slot antennas is very complex. Because engineering design formulas and curves for such antennas are not available in the open literature, designers have been forced to implement iterative processes of fabricating and testing multiple prototypes to derive design databases, each unique for a specific combination of operating frequency and set of waveguide tube dimensions. The expensive, time-consuming nature of these processes has inhibited the use of resonant edge-slot antennas. The present modern approach reduces costs by making it unnecessary to build and test multiple prototypes. As an additional benefit, this approach affords a capability to design an array of slots having different dimensions to taper the antenna illumination to reduce the amplitudes of unwanted side lobes. The heart of the modern approach is the use of the latest commercially available microwave-design software, which implements finite-element models of electromagnetic fields in and around waveguides, antenna elements, and similar components. Instead of building and testing prototypes, one builds a database and constructs design curves from the results of computational simulations for sets of design parameters. The figure shows a resonant edge-slot antenna designed following this approach. Intended for use as part of a radiometer operating at a frequency of 10.7 GHz, this antenna

  13. Two-Arm Flexible Thermal Strap

    NASA Technical Reports Server (NTRS)

    Urquiza, Eugenio; Vasquez, Cristal; Rodriquez, Jose I.; Leland, Robert S.; VanGorp, Byron E.

    2011-01-01

    Airborne and space infrared cameras require highly flexible direct cooling of mechanically-sensitive focal planes. A thermal electric cooler is often used together with a thermal strap as a means to transport the thermal energy removed from the infrared detector. While effective, traditional thermal straps are only truly flexible in one direction. In this scenario, a cooling solution must be highly conductive, lightweight, able to operate within a vacuum, and highly flexible in all axes to accommodate adjustment of the focal plane while transmitting minimal force. A two-armed thermal strap using three end pieces and a twisted section offers enhanced elastic movement, significantly beyond the motion permitted by existing thermal straps. This design innovation allows for large elastic displacements in two planes and moderate elasticity in the third plane. By contrast, a more conventional strap of the same conductance offers less flexibility and asymmetrical elasticity. The two-arm configuration reduces the bending moment of inertia for a given conductance by creating the same cross-sectional area for thermal conduction, but with only half the thickness. This reduction in the thickness has a significant effect on the flexibility since there is a cubic relationship between the thickness and the rigidity or bending moment of inertia. The novelty of the technology lies in the mechanical design and manufacturing of the thermal strap. The enhanced flexibility will facilitate cooling of mechanically sensitive components (example: optical focal planes). This development is a significant contribution to the thermal cooling of optics. It is known to be especially important in the thermal control of optical focal planes due to their highly sensitive alignment requirements and mechanical sensitivity; however, many other applications exist including the cooling of gimbal-mounted components.

  14. Electrical Testing of the Full-Scale model of the NSTX HHFW Antenna Array

    SciTech Connect

    Fadnek, A.; Ryan, P.M.; Sparks, D.O.; Swain, D.W.; Wilgen, J.B.

    1999-04-12

    The 30 MHz high harmonic fast wave (HHFW) antenna array for NSTX consists of 12 current straps, evenly spaced in the toroidal direction. Each pair of straps is connected as a half-wave resonant loop and will be driven by one transmitter, allowing rapid phase shift between transmitters. A decoupling network using shunt stub tuners has been designed to compensate for the mutual inductive coupling between adjacent current straps, effectively isolating the six transmitters from one another. One half of the array, consisting of six full-scale current strap modules, three shunt stub decouplers, and powered by three phase-adjustable rf amplifiers had been built for electrical testing at ORNL. Low power testing includes electrical characterization of the straps, operation and performance of the decoupler system, and mapping of the rf fields in three dimensions.

  15. Whip antenna design for portable rf systems

    NASA Astrophysics Data System (ADS)

    Ponnapalli, Saila; Canora, Frank J.

    1995-12-01

    Whip type antennas are probably the most commonly used antennas in portable rf systems, such as cordless and cellular phones, rf enabled laptop computers, personal digital assistants (PDAs), and handheld computers. Whip antennas are almost always mounted on the chassis which contains the radio and other electronics. The chassis is usually a molded plastic which is coated with a conducting paint for EMI purposes. The chassis which appears as a lossy conductor to the antenna, has several effects -- detuning, altering the gain of the antenna, and shadowing its radiation pattern. Extensive modeling and measurements must be performed in order to fully characterize the affects of the chassis on the whip antenna, and to optimize antenna type, orientation and position. In many instances, modeling plays a more important role in prediction of the performance of whip antennas, since measurements become difficult due to the presence of common mode current on feed cables. In this paper models and measurements are used to discuss the optimum choice of whip antennas and the impact of the chassis on radiation characteristics. A modeling tool which has been previously described and has been successfully used to predict radiated field patterns is used for simulations, and measured and modeled results are shown.

  16. Antenna Designs for the Mars Exploration Rovers (MER) Spacecraft, Lander, and Rover

    NASA Technical Reports Server (NTRS)

    Vacchione, Joseph; Thelen, Michael; Brown, Paula; Huang, John; Kelly, Ken; Krishnan, Satish

    2001-01-01

    This presentation focuses on the design of antennas for the Mars Exploration Rovers (MER). Specific topics covered include: MER spacecraft architecture, the evolution of an antenna system, MER cruise stage antennas, antenna stacks, the heat-shield/back shell antenna, and lander and rover antennas. Additionally, the mission's science objectives are reviewed.

  17. ORNL compact loop antenna design for TFTR and Tore Supra

    SciTech Connect

    Taylor, D.J.; Baity, F.W.; Bryan, W.E.; Hoffman, D.J.; McIlwain, R.L. ); Ray, J.M. )

    1987-01-01

    The goal supplemental ion cyclotron resonance heating (ICRH) of fusion plasma is to deliver power at high efficiencies deep within the plasma. The technology for fast-wave ICRH has reached the point of requiring proof-of-performance'' demonstration of specific antenna configurations of specific antenna configurations and their mechanical adequacy for operating in a fusion environment. Oak Ridge National Laboratory (ORNL) has developed the compact loop antenna concept based on a resonant double loop (RDL) configuration for use in both Tokamak Fusion Test Reactor (TFTR) and the Tore Supra ICRH programs. A description and a comparison of the technologies developed in the two designs are presented. The electrical circuit and the mechanical philosophy employed are the same for both antennas, but different operating environments result in substantial differences in the design of specific components. The ORNL TFTR antenna is designed to deliver 4 MW over a 2-s pulse, and the ORNL Tore Supra antenna is designed for 4 MW and essentially steady-state conditions. The TFTR design embodies the first operations compact RDL antenna, and the Tore Supra antenna extends the technology to an operational duty cycle consistent with reactor-relevant applications. 7 refs., 5 figs.

  18. Design and development of conformal antenna composite structure

    NASA Astrophysics Data System (ADS)

    Xie, Zonghong; Zhao, Wei; Zhang, Peng; Li, Xiang

    2017-09-01

    In the manufacturing process of the common smart skin antenna, the adhesive covered on the radiating elements of the antenna led to severe deviation of the resonant frequency, which degraded the electromagnetic performance of the antenna. In this paper, a new component called package cover was adopted to prevent the adhesive from covering on the radiating elements of the microstrip antenna array. The package cover and the microstrip antenna array were bonded together as packaged antenna which was then embedded into the composite sandwich structure to develop a new structure called conformal antenna composite structure (CACS). The geometric parameters of the microstrip antenna array and the CACS were optimized by the commercial software CST microwave studio. According to the optimal results, the microstrip antenna array and the CACS were manufactured and tested. The experimental and numerical results of electromagnetic performance showed that the resonant frequency of the CACS was close to that of the microstrip antenna array (with error less than 1%) and the CACS had a higher gain (about 2 dB) than the microstrip antenna array. The package system would increase the electromagnetic radiating energy at the design frequency nearly 66%. The numerical model generated by CST microwave studio in this study could successfully predict the electromagnetic performance of the microstrip antenna array and the CACS with relatively good accuracy. The mechanical analysis results showed that the CACS had better flexural property than the composite sandwich structure without the embedment of packaged antenna. The comparison of the electromagnetic performance for the CACS and the MECSSA showed that the package system was useful and effective.

  19. Advanced Antenna Design for NASA's EcoSAR Instrument

    NASA Technical Reports Server (NTRS)

    Du Toit, Cornelis F.; Deshpande, Manohar; Rincon, Rafael F.

    2016-01-01

    Advanced antenna arrays were designed for NASA's EcoSAR airborne radar instrument. EcoSAR is a beamforming synthetic aperture radar instrument designed to make polarimetric and "single pass" interferometric measurements of Earth surface parameters. EcoSAR's operational requirements of a 435MHz center frequency with up to 200MHz bandwidth, dual polarization, high cross-polarization isolation (> 30 dB), +/- 45deg beam scan range and antenna form-factor constraints imposed stringent requirements on the antenna design. The EcoSAR project successfully developed, characterized, and tested two array antennas in an anechoic chamber. EcoSAR's first airborne campaign conducted in the spring of 2014 generated rich data sets of scientific and engineering value, demonstrating the successful operation of the antennas.

  20. Optical antenna design for fluorescence enhancement in the ultraviolet.

    PubMed

    Jiao, Xiaojin; Blair, Steve

    2012-12-31

    Through rational design, we compare the performance of three plasmonic antenna structures for UV fluorescence enhancement. Among the antenna performance metrics considered are the local increase in excitation intensity and the increase in quantum efficiency, the product of which represents the net fluorescence enhancement. With realistic structures in aluminum, we predict that greater than 100× net enhancement can be obtained.

  1. Design and analysis of a folded Fresnel Zone Plate antenna

    NASA Astrophysics Data System (ADS)

    Ji, Yu; Fujita, Masaharu

    1994-08-01

    Based on the Kirchhoff-Huygens diffraction theory, a simple analytical method of a planar folded Fresnel zone-plate (FZP), that is the case when a planar reflector is placed behind the zone plates, has been developed. According to the numerical calculation results, the design procedure of the FZP antenna has been presented, and its focusing characteristics and gain-optimized conditions have been discussed. The variations of the focal field distribution with the antenna parameters such as zone numbers, focal length and antenna diameter and the radiation power patterns of the FZP have been simulated numerically. To take a good balance of both receiving and transmitting antennas, at 60GHz operating frequency, the focal length should be designed as a half of the antenna diameter and the zone number should be from 10 to 15. The results in this work show that the folded FZP has good focal characteristics and off-axis performance, and its antenna gain can be optimized by the suitable antenna parameter design. The possibility of applying the folded FZP as a low cost and high gain antenna without strict manufacturing requirement for millimeter-wave communications has been shown.

  2. Silicone Rubber Superstrate Loaded Patch Antenna Design Using Slotting Technique

    NASA Astrophysics Data System (ADS)

    Kaur, Bhupinder; Saini, Garima; Saini, Ashish

    2016-09-01

    For the protection of antenna from external environmental conditions, there is a need that antenna should be covered with a stable, non-reactive, highly durable and weather resistive material which is insensitive to changing external environment. Hence, in this paper silicone rubber is proposed as a superstrate layer for patch antenna for its protection. The electrical properties of silicon rubber sealant are experimentally found out and its effect of using as superstrate on coaxial fed microstrip patch antenna using transmission line model is observed. The overall performance is degraded by slightly after the use of superstrate. Further to improve the performance of superstrate loaded antenna, patch slots and ground defects have been proposed. The proposed design achieves the wideband of 790 MHz (13.59 %), gain of 7.12 dB, VSWR of 1.12 and efficiency of 83.02 %.

  3. Very Broad Band VHF/UHF Omnidirectional Antenna Design Study

    DTIC Science & Technology

    1989-12-01

    antennas, is unsuitable for the given appli- cation because its pattern is bi- directional and produces a broad lobe perpendicular to both sides of the...starting point for the new design. The objective was to modify the LPDA to fit the A/V and concurrently achieve a nearly omni- directional radiation pattern...has been included in this review. In particular, many conformal designs including microstrip patch, stripline, slot, and cavity antennas have been

  4. Modeling and design of antennas for implantable telemetry applications.

    PubMed

    Venkatasubramanian, Arun; Gifford, Brandon

    2016-08-01

    Incorporating an RF communications link in an implanted medical device can increase its range of applicability and improve quality of life for the patient. Developments in support electronics decrease design risk, but the implanted antenna remains a critical component of a communications link that operates at very low received power. Transmitted power is limited both by regulatory restrictions and, for most implanted devices, by power source capacity. Dielectric losses and wave trapping in the body result in transmission losses much greater than seen in free space communications. Small antenna size is required for physiological acceptability. Design optimization must trade antenna size, geometric complexity and material cost against efficiency, operating bandwidth and driving power. Designs must also work in differing body morphologies. This paper describes the methodology for simulation and the impact of different body morphologies on implant antenna performance. An understanding of these is required to optimize antenna performance and meet ever increasing range requirements. It is shown that depending on the use case and end user morphology, the antenna performance can be incredible successful or marginally adequate. Given the high sensitivity to small changes in thickness of the human body, testing the antenna for a range of BMI and body fat percentages is a must to truly characterize its performance.

  5. CW (Continuous Wave) Antenna Design and Testing.

    DTIC Science & Technology

    1982-08-01

    it drives up labor cost significantly due to such things as negotations for use of the land and cost of returning the land to its original...sophistication that is incompatible with the operational concept laid out for the CW system. The decision to operate the antenna in close physical proximity to

  6. Design, performance, and grounding aspects of the International Thermonuclear Experimental Reactor ion cyclotron range of frequencies antenna

    SciTech Connect

    Durodié, F. Dumortier, P.; Vrancken, M.; Messiaen, A.; Huygen, S.; Louche, F.; Van Schoor, M.; Vervier, M.; Winkler, K.

    2014-06-15

    ITER's Ion Cyclotron Range of Frequencies (ICRF) system [Lamalle et al., Fusion Eng. Des. 88, 517–520 (2013)] comprises two antenna launchers designed by CYCLE (a consortium of European associations listed in the author affiliations above) on behalf of ITER Organisation (IO), each inserted as a Port Plug (PP) into one of ITER's Vacuum Vessel (VV) ports. Each launcher is an array of 4 toroidal by 6 poloidal RF current straps specified to couple up to 20 MW in total to the plasma in the frequency range of 40 to 55 MHz but limited to a maximum system voltage of 45 kV and limits on RF electric fields depending on their location and direction with respect to, respectively, the torus vacuum and the toroidal magnetic field. A crucial aspect of coupling ICRF power to plasmas is the knowledge of the plasma density profiles in the Scrape-Off Layer (SOL) and the location of the RF current straps with respect to the SOL. The launcher layout and details were optimized and its performance estimated for a worst case SOL provided by the IO. The paper summarizes the estimated performance obtained within the operational parameter space specified by IO. Aspects of the RF grounding of the whole antenna PP to the VV port and the effect of the voids between the PP and the Blanket Shielding Modules (BSM) surrounding the antenna front are discussed. These blanket modules, whose dimensions are of the order of the ICRF wavelengths, together with the clearance gaps between them will constitute a corrugated structure which will interact with the electromagnetic waves launched by ICRF antennas. The conditions in which the grooves constituted by the clearance gaps between the blanket modules can become resonant are studied. Simple analytical models and numerical simulations show that mushroom type structures (with larger gaps at the back than at the front) can bring down the resonance frequencies, which could lead to large voltages in the gaps between the blanket modules and perturb the

  7. Interdisciplinary design analysis of a precision spacecraft antenna

    NASA Technical Reports Server (NTRS)

    Steinbach, R. E.; Winegar, S. R.

    1985-01-01

    The Advanced Communications Technology Satellite (ACTS) will operate in the 20/30 GHz range (Ka Band), and will include a multi-beam antenna (MBA) capable of 0.3 degree scanning spot beams with very high beam-to-beam isolation. The antenna Radio Frequency (RF) performance requirements lead to stringent requirements on the antenna reflector surface shape. A prediction of RF performance of a potential flight model antenna reflector operating under space environmental conditions is made using a radiant heat input model (TRASYS), a thermal analyzer (SINDA), a structural model (NASTRAN), and RF far field pattern simulation. Interfacing software has been written to pass thermal model temperature results to the structural model, and structural model thermal deformation results to the RF far field pattern simulation. A complete analysis can be performed in a single computer run, and potential changes in design can be quickly and easily evaluated using this interdisciplinary design analysis tool.

  8. Interdisciplinary design analysis of a precision spacecraft antenna

    NASA Technical Reports Server (NTRS)

    Steinbach, R. E.; Winegar, S. R.

    1985-01-01

    The Advanced Communications Technology Satellite (ACTS) will operate in the 20/30 GHz range (Ka Band), and will include a multi-beam antenna (MBA) capable of 0.3 degree scanning spot beams with very high beam-to-beam isolation. The antenna Radio Frequency (RF) performance requirements lead to stringent requirements on the antenna reflector surface shape. A prediction of RF performance of a potential flight model antenna reflector operating under space environmental conditions is made using a radiant heat input model (TRASYS), a thermal analyzer (SINDA), a structural model (NASTRAN), and RF far field pattern simulation. Interfacing software has been written to pass thermal model temperature results to the structural model, and structural model thermal deformation results to the RF far field pattern simulation. A complete analysis can be performed in a single computer run, and potential changes in design can be quickly and easily evaluated using this interdisciplinary design analysis tool.

  9. Textile materials for the design of wearable antennas: a survey.

    PubMed

    Salvado, Rita; Loss, Caroline; Gonçalves, Ricardo; Pinho, Pedro

    2012-11-15

    In the broad context of Wireless Body Sensor Networks for healthcare and pervasive applications, the design of wearable antennas offers the possibility of ubiquitous monitoring, communication and energy harvesting and storage. Specific requirements for wearable antennas are a planar structure and flexible construction materials. Several properties of the materials influence the behaviour of the antenna. For instance, the bandwidth and the efficiency of a planar microstrip antenna are mainly determined by the permittivity and the thickness of the substrate. The use of textiles in wearable antennas requires the characterization of their properties. Specific electrical conductive textiles are available on the market and have been successfully used. Ordinary textile fabrics have been used as substrates. However, little information can be found on the electromagnetic properties of regular textiles. Therefore this paper is mainly focused on the analysis of the dielectric properties of normal fabrics. In general, textiles present a very low dielectric constant that reduces the surface wave losses and increases the impedance bandwidth of the antenna. However, textile materials are constantly exchanging water molecules with the surroundings, which affects their electromagnetic properties. In addition, textile fabrics are porous, anisotropic and compressible materials whose thickness and density might change with low pressures. Therefore it is important to know how these characteristics influence the behaviour of the antenna in order to minimize unwanted effects. This paper presents a survey of the key points for the design and development of textile antennas, from the choice of the textile materials to the framing of the antenna. An analysis of the textile materials that have been used is also presented.

  10. Textile Materials for the Design of Wearable Antennas: A Survey

    PubMed Central

    Salvado, Rita; Loss, Caroline; Gonçalves, Ricardo; Pinho, Pedro

    2012-01-01

    In the broad context of Wireless Body Sensor Networks for healthcare and pervasive applications, the design of wearable antennas offers the possibility of ubiquitous monitoring, communication and energy harvesting and storage. Specific requirements for wearable antennas are a planar structure and flexible construction materials. Several properties of the materials influence the behaviour of the antenna. For instance, the bandwidth and the efficiency of a planar microstrip antenna are mainly determined by the permittivity and the thickness of the substrate. The use of textiles in wearable antennas requires the characterization of their properties. Specific electrical conductive textiles are available on the market and have been successfully used. Ordinary textile fabrics have been used as substrates. However, little information can be found on the electromagnetic properties of regular textiles. Therefore this paper is mainly focused on the analysis of the dielectric properties of normal fabrics. In general, textiles present a very low dielectric constant that reduces the surface wave losses and increases the impedance bandwidth of the antenna. However, textile materials are constantly exchanging water molecules with the surroundings, which affects their electromagnetic properties. In addition, textile fabrics are porous, anisotropic and compressible materials whose thickness and density might change with low pressures. Therefore it is important to know how these characteristics influence the behaviour of the antenna in order to minimize unwanted effects. This paper presents a survey of the key points for the design and development of textile antennas, from the choice of the textile materials to the framing of the antenna. An analysis of the textile materials that have been used is also presented. PMID:23202235

  11. Structural design of a high performance microstrip antenna

    NASA Astrophysics Data System (ADS)

    Cowles, P. R.

    The general aspects of series array design are considered from the viewpoint of structure and materials and a particular solution which has been adapted in the case of an 'azimuth' microwave landing system (MLS) antenna is described. The antenna, about one third the mass of a conventional slotted waveguide array, assists frangibility which is an important property of equipment placed on the center-line of an airport runway.

  12. Anti-Skywave AM Broadcast Antenna Design.

    DTIC Science & Technology

    1987-03-01

    Admiral R. C. Austin D . A. Schrady Superintendent Provost This thesis is prepared in conjunction with research sponscred in part by Naval Ocean Systems...I J ’ ~~~ D t 1 :-".. t 1-13 t . .. .. . . TABLE OF CONTENTS 1. INTRODUCTION .......................................... I I A. NEED FOR THE... D . SCOPE AND LIMITATIONS ............................. 13 II. THE ANALYSIS OF BIBY’S ANTI-SKYWAVE ANTENNA ......... 16 A. DESCRIPTION OF BIBY’S ANTI

  13. Design concepts for large antenna reflectors

    NASA Technical Reports Server (NTRS)

    Hedgepeth, J. M.

    1981-01-01

    A type of antenna reflector was studied in which a stiff structure is constructed to hold a membrane like reflector mesh in the correct position. An important basic restriction is that the mesh be controlled only by the structure and that no additional local shaping be employed. Furthermore, attention is confined to structures in which no adjustments would be made on assembly. Primary attention is given to the tetrahedral truss configuration because of its outstanding stiffness and dimensional stability.

  14. Effect of backpack shoulder straps length on cervical posture and upper trapezius pressure pain threshold

    PubMed Central

    Abdelraouf, Osama Ragaa; Hamada, Hamada Ahmed; Selim, Ali; Shendy, Wael; Zakaria, Hoda

    2016-01-01

    [Purpose] This study was performed to investigate the effect of the length of backpack shoulder straps on upper trapezius muscle pain threshold and craniovertebral angle. [Subjects and Methods] There were 25 participants, with ages from 15 to 23 years old. Upper trapezius pain threshold and craniovertebral angle were measured for all subjects without the backpack then re-measured after walking on a treadmill for 15 min under 2 conditions: 1) wearing a backpack with short straps; and 2) wearing a backpack with long straps. [Results] there was a significant reduction in upper trapezius pain threshold and craniovertebral angle while carrying a backpack with long shoulder straps, compared to use of a backpack with short shoulder straps or no backpack. [Conclusion] A backpack with short straps is less harmful than a backpack with long straps. This result should be considered in ergonomic design of backpacks to reduce the incidence of various physiological and biomechanical disorders. PMID:27799665

  15. Preliminary design of a redundant strapped down inertial navigation unit using two-degree-of-freedom tuned-gimbal gyroscopes

    NASA Technical Reports Server (NTRS)

    1976-01-01

    This redundant strapdown INS preliminary design study demonstrates the practicality of a skewed sensor system configuration by means of: (1) devising a practical system mechanization utilizing proven strapdown instruments, (2) thoroughly analyzing the skewed sensor redundancy management concept to determine optimum geometry, data processing requirements, and realistic reliability estimates, and (3) implementing the redundant computers into a low-cost, maintainable configuration.

  16. Design and control of phased ICRF antenna arrays

    SciTech Connect

    Goulding, R.H.; Baity, F.W.; Hoffman, D.J.

    1993-11-01

    Phased antenna arrays operating in the ion cyclotron range of frequencies (ICRF) are used to produce highly directional wave spectra, primarily for use in current drive experiments. RF current drive using phased antennas has been demonstrated in both the JET and DIII-D tokamaks, and both devices are planning to operate new four-element arrays beginning early next year. Features of antenna design that are relevant to phased operation and production of directional spectra are reviewed. Recent advances in the design of the feed circuits and the related control systems for these arrays should substantially improve their performance, by reducing the coupling seen by the matching networks and rf power supplies caused by the mutual impedance of the array elements. The feed circuit designs for the DIII-D and JET phased antenna arrays are compared. The two configurations differ significantly due to the fact that one power amplifier is used for the entire array in the former case, and one per element in the latter. The JET system uses automatic feedback control of matching, phase and amplitude of antenna currents, and the transmitter power balance. The design of this system is discussed, and a time dependent model used to predict its behavior is described.

  17. Study and design of the ion cyclotron resonance heating system for the stellarator Wendelstein 7-X

    SciTech Connect

    Ongena, J.; Messiaen, A.; Van Eester, D.; Schweer, B.; Dumortier, P.; Durodie, F.; Kazakov, Ye. O.; Louche, F.; Vervier, M.; Koch, R.; Krivska, A.; Lyssoivan, A.; Van Schoor, M.; Wauters, T.; Borsuk, V.; Neubauer, O.; Schmitz, O.; Altenburg, Y.; Baylard, C.; and others

    2014-06-15

    The current status of the mechanical and electromagnetic design for the ICRF antenna system for W7-X is presented. Two antenna plugins are discussed: one consisting of a pair of straps with pre-matching to cover the first frequency band, 25–38 MHz, and a second one consisting of two short strap triplets to cover a frequency band around 76 MHz. This paper focusses on the two strap antenna for the lower frequency band. Power coupling of the antenna to a reference plasma profile is studied with the help of the codes TOPICA and Microwave Studio that deliver the scattering matrix needed for the optimization of the geometric parameters of the straps and antenna box. Radiation power spectra for different phasings of the two straps are obtained using the code ANTITER II and different heating scenario are discussed. The potential for heating, fast particle generation, and current drive is discussed. The problem of RF coupling through the plasma edge and of edge power deposition is summarized. Important elements of the complete ion cyclotron resonance heating system are discussed: a resonator circuit with tap feed to limit the maximum voltage in the system, and a decoupler to counterbalance the large mutual coupling between the 2 straps. The mechanical design highlights the challenges encountered with this antenna: adaptation to a large variety of plasma configurations, the limited space within the port to accommodate the necessary matching components and the watercooling needed for long pulse operation.

  18. Study and design of the ion cyclotron resonance heating system for the stellarator Wendelstein 7-X

    NASA Astrophysics Data System (ADS)

    Ongena, J.; Messiaen, A.; Van Eester, D.; Schweer, B.; Dumortier, P.; Durodie, F.; Kazakov, Ye. O.; Louche, F.; Vervier, M.; Koch, R.; Krivska, A.; Lyssoivan, A.; Van Schoor, M.; Wauters, T.; Borsuk, V.; Neubauer, O.; Schmitz, O.; Offermans, G.; Altenburg, Y.; Baylard, C.; Birus, D.; Bozhenkov, S.; Hartmann, D. A.; Kallmeyer, J. P.; Renard, S.; Wolf, R. C.; Fülöp, T.

    2014-06-01

    The current status of the mechanical and electromagnetic design for the ICRF antenna system for W7-X is presented. Two antenna plugins are discussed: one consisting of a pair of straps with pre-matching to cover the first frequency band, 25-38 MHz, and a second one consisting of two short strap triplets to cover a frequency band around 76 MHz. This paper focusses on the two strap antenna for the lower frequency band. Power coupling of the antenna to a reference plasma profile is studied with the help of the codes TOPICA and Microwave Studio that deliver the scattering matrix needed for the optimization of the geometric parameters of the straps and antenna box. Radiation power spectra for different phasings of the two straps are obtained using the code ANTITER II and different heating scenario are discussed. The potential for heating, fast particle generation, and current drive is discussed. The problem of RF coupling through the plasma edge and of edge power deposition is summarized. Important elements of the complete ion cyclotron resonance heating system are discussed: a resonator circuit with tap feed to limit the maximum voltage in the system, and a decoupler to counterbalance the large mutual coupling between the 2 straps. The mechanical design highlights the challenges encountered with this antenna: adaptation to a large variety of plasma configurations, the limited space within the port to accommodate the necessary matching components and the watercooling needed for long pulse operation.

  19. Spotter strap for the prevention of wheelchair tipping.

    PubMed

    Kirby, R L; Lugar, J A

    1999-10-01

    Injuries caused by wheelchair rear-tipping accidents are common. This article reports on the safety and effectiveness of a spotter strap that attaches to the cross-brace or frame below the center of gravity of an occupied wheelchair. We videotaped five therapists spotting 89 wheelchair users while the users each performed six tasks that were designed to induce rear instability. We induced 16 episodes of complete rear tipping. In all cases, the spotter strap allowed the spotter to stay out of the way during the task, but step in easily when necessary to prevent the wheelchair user from being injured. In one instance, the spotter needed assistance lifting a heavy subject to the upright position after catching the subject with the strap. In summary, the spotter strap is a safe and effective device. We recommend its use when there is a high risk of a rear-tipping accident.

  20. Antenna Design Considerations for the Advanced Extravehicular Mobility Unit

    NASA Technical Reports Server (NTRS)

    Bakula, Casey J.; Theofylaktos, Onoufrios

    2015-01-01

    NASA is designing an Advanced Extravehicular Mobility Unit (AEMU)to support future manned missions beyond low-Earth orbit (LEO). A key component of the AEMU is the communications assembly that allows for the wireless transfer of voice, video, and suit telemetry. The Extravehicular Mobility Unit (EMU) currently used on the International Space Station (ISS) contains a radio system with a single omni-directional resonant cavity antenna operating slightly above 400 MHz capable of transmitting and receiving data at a rate of about 125 kbps. Recent wireless communications architectures are calling for the inclusion of commercial wireless standards such as 802.11 that operate in higher frequency bands at much higher data rates. The current AEMU radio design supports a 400 MHz band for low-rate mission-critical data and a high-rate band based on commercial wireless local area network (WLAN) technology to support video, communication with non-extravehicular activity (EVA) assets such as wireless sensors and robotic assistants, and a redundant path for mission-critical EVA data. This paper recommends the replacement of the existing EMU antenna with a new antenna that maintains the performance characteristics of the current antenna but with lower weight and volume footprints. NASA has funded several firms to develop such an antenna over the past few years, and the most promising designs are variations on the basic patch antenna. This antenna technology at UHF is considered by the authors to be mature and ready for infusion into NASA AEMU technology development programs.

  1. Development of a fishbone travelling wave antenna for LHD

    NASA Astrophysics Data System (ADS)

    Takase, Y.; Moeller, C. P.; Seki, T.; Takeuchi, N.; Watari, T.; Callis, R.; Ejiri, A.; Ikezi, H.; Kasahara, H.; Kasuya, N.; Kumazawa, R.; Mutoh, T.; Ohkubo, K.; Olstad, R. A.; Saigusa, M.; Saito, K.; Shiraiwa, S.; Taniguchi, T.; Torii, H.; Wada, H.; Yamagishi, K.; Yamamoto, T.

    2004-02-01

    The 'fishbone' fast wave travelling wave antenna was developed for LHD to provide a capability for rotational transform profile control by current drive. The fishbone antenna is equivalent to two combline antennae stacked vertically. The antenna operates around 75 MHz and excites a wavenumber of 14 m-1 when the phase difference between adjacent current straps is 90°. A test of a combline antenna with plasma load on the TST-2 spherical tokamak suggested the possibility that this type of antenna does not need to be installed in the immediate vicinity of the last closed flux surface. Optimization of the design was performed based on measurements on mock-up antennas and model calculations. In the fishbone antenna, controlled excitation of the even mode (with currents in the top and bottom halves of a current strap in the same direction) is necessary. A predominant excitation of the even mode was realized in the LHD fishbone antenna with simulated loading by selecting an appropriate operating frequency.

  2. The Design of Impedance- Matching Networks for Broadband Antennas.

    DTIC Science & Technology

    1987-09-01

    AD-RIB? GN THE DESIGN OF IMPEDANCE - MATCHING NETWORKS FOR / BRORDBAM RNTENNAS(U) NAVAL OCEAN SYSTEMS CENTER SAN DDIEGO CA S T LI .ET AL. SEP 87 NOSC...z Technical Document 1148 September 1987 The Design of Impedance - Matching Networks for Broadband Antennas o S. T.LU DTIC D. W. S. TamSJANO06 1988~1...over a given frequency band of interest. The device used to perform this impedance matching is called an antenna matching network. The number of

  3. Magneto-Dielectric Wire Antennas Theory and Design

    NASA Astrophysics Data System (ADS)

    Sebastian, Tom

    supported by the magneto-dielectric structure and leads to useful design rules connecting the permeability of the material to the cross sectional area of the antenna in relation to the desired frequency of operation. The Green function problem of the permeable prolate spheroidal antenna is also solved as a good approximation to a finite cylinder.

  4. Optimum design of Cassegrain antenna for space laser communication

    NASA Astrophysics Data System (ADS)

    Hu, Yuan; Jiang, Lun; Wang, Chao; Li, Yingchao

    2016-10-01

    The divergence angle is very important index in space laser communication for energy transfer. Typically, the large aperture telescope as optical antenna is used for angle compression, and the divergence angle of communication beam is usually calculated by diffraction limit angle equation 1.22λ/D. This equation expresses the diffraction of a spherical wave through a circular aperture. However, the light source commonly used laser with a Gaussian distribution, and the optical antenna is central obscurations. The antenna parameters which is obscuration ratio and Gaussian beam apodization were significantly relative with the far field energy. In this study, we obtain the mathematic relation between the divergence angle, energy loss and the antenna parameters. From the relationship, we know that the divergence angle smaller as the increase of antenna obscuration ratio. It would tend to enhance the far-field energy density. But a larger obscuration ratio will increase the energy loss. At the same time, the increase of Gaussian beam apodization resulted in the energy of first diffraction ring was raised but the radius of first ring was increased. They were conflict. And then, the antenna parameters of trade-off was found from curves of obscuration ratio and curves of divergence angle. The parameters of a Cassegrain antenna was optimum designed for the energy maximization, and considerd the apodization from mechanical structure blocking. The long-distance laser communications were successful in these airborne tests. Stable communication was demonstrated. The energy gain is sufficient for SNR of high-bandwidth transmission in atmospheric channel.

  5. ICRF antenna matching system with ferrite tuners for the Alcator C-Mod tokamak

    NASA Astrophysics Data System (ADS)

    Lin, Y.; Binus, A.; Wukitch, S. J.; Koert, P.; Murray, R.; Pfeiffer, A.

    2015-12-01

    Real-time fast ferrite tuning (FFT) has been successfully implemented on the ICRF antennas on Alcator C-Mod. The former prototypical FFT system on the E-port 2-strap antenna has been upgraded using new ferrite tuners that have been designed specifically for the operational parameters of the Alcator C-Mod ICRF system (˜ 80 MHz). Another similar FFT system, with two ferrite tuners and one fixed-length stub, has been installed on the transmission line of the D-port 2-strap antenna. These two systems share a Linux-server-based real-time controller. These FFT systems are able to achieve and maintain the reflected power to the transmitters to less than 1% in real time during the plasma discharges under almost all plasma conditions, and help ensure reliable high power operation of the antennas. The innovative field-aligned (FA) 4-strap antenna on J-port has been found to have an interesting feature of loading insensitivity vs. plasma conditions. This feature allows us to significantly improve the matching for the FA J-port antenna by installing carefully designed stubs on the two transmission lines. The reduction of the RF voltages in the transmission lines has enabled the FA J-port antenna to deliver 3.7 MW RF power to plasmas out of the 4 MW source power in high performance I-mode plasmas.

  6. Design of Broadband Wire Antennas for Frequency Hopping Applications

    DTIC Science & Technology

    1993-03-01

    INTRODUCTION .................. ................... 1 A. BACKGROUND ................. .................. 1 B. RESEARCH DEFINITIONS ...the frequency band and thus increase the radiating power of the antenna [Ref. 3]. 1 B. RESEARCH DEFINITIONS This research will attempt to design a...Ov0erall Paralel connection Response 87 W E R E Figure 5.25 Overall Efficiency of The System 88 i E. PARALLEL CONNECTION WITH LOSSY INDUCTORS Up to

  7. Design of compact electromagnetic impulse radiating antenna for melanoma treatment.

    PubMed

    Arockiasamy, Petrishia; Mohan, Sasikala

    2016-01-01

    Cancer therapy is one of the several new applications which use nanosecond and subnanosecond high voltage pulses. New treatment based on electromagnetic (EM) fields have been developed as non-surgical and minimally invasive treatments of tumors. In particular, subnanosecond pulses can introduce important non-thermal changes in cell biology, especially the permeabilization of the cell membrane. The motivation behind this work is to launch intense subnanosecond pulses to the target (tumors) non-invasively. This works focuses on the design of a compact intense pulsed EM radiating antenna. In tense EM waves radiated at the first focal point of the Prolate Spheroidal Reflector (PSR) are focused at the second focal point where the target (tumor) is present. Two antennas with PSR but fed with different compact wave radiator are designed to focus pulsed field at the second focal point. The PSR with modified bicone antenna feed and PSR with elliptically tapered horn antenna feed are designed. The design parameters and radiation performance are discussed.

  8. RFID antenna design for circular polarization in UHF band

    NASA Astrophysics Data System (ADS)

    Shahid, Hamza; Khan, Muhammad Talal Ali; Tayyab, Umais; Irshad, Usama Bin; Alkhazraji, Emad; Javaid, Muhammad Sharjeel

    2017-05-01

    A miniature half cross dipole antenna for defense and aerospace RFID applications in UHF band is presented. The dipole printed line arms are half crossed shape on top of dielectric substrate backed by reactive impedance surface. The antenna fed by a coaxial cable at the gap separating the dipole arms. Our design is intended to work at 2.42 GHz for RFID readers. The radiation pattern obtained has HPBW of 112, return loss of 22.24 dB and 90 MHz bandwidth.

  9. Miniaturization design and implementation of magnetic field coupled RFID antenna

    NASA Astrophysics Data System (ADS)

    Hu, Tiling

    2013-03-01

    The development of internet of things has brought new opportunities and challenges to the application of RFID tags. Moreover, the Miniaturization application trend of tags at present has become the mainstream of development. In this paper, the double-layer design is to reduce the size of HF antenna, and the magnetic null point of magnetic reconnection region between the RLC resonant circuit and the reader provides sufficient energy to the miniaturization of antenna. The calculated and experimental results show that the miniaturization of HF antennas can meet the reading and writing requirement of the international standard ISO/IEC14443 standard. The results of this paper may make a positive contribution to the applications of RFID technology.

  10. The ORNL fast wave ICRF (Ion Cyclotron Range of Frequencies) antenna for Alcator C-Mod

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Conner, D.L.; Hammonds, C.J.; Ping, J.L.; Riemer, B.W.; Ryan, P.M.; Taylor, D.J.; Wysor, R.B.; Yugo, J.J. )

    1989-01-01

    A fast wave ICRF antenna is being designed for Alcator C-Mod which is prototypical in many respects of the baseline launcher design for the Compact Ignition Tokamak (CIT). The C-Mod launcher has a single current strap, with a strap and cavity geometry very similar to one quadrant of the CIT launcher, which has four straps in a 2 {times} 2 configuration. The antenna fits entirely within an 8 in. wide by 25 in. long port and is radially movable over a distance of 15 cm. It will operate at a frequency of 80 MHz for pulse lengths up to 1 s, at a maximum power level of 2 MW, corresponding to a power flux of >1.5 kW/cm{sup 2}. The antenna is an end fed double loop configuration in which the current strap is grounded in the middle to provide mechanical support. The design includes a disruption support system which accommodates thermal expansion of the antenna box while supporting large disruption loads. It also includes a novel matching system consisting of an external resonant loop with two shunt capacitors serving as tuning/matching elements. 8 refs., 5 figs., 12 tabs.

  11. Conceptual design for scaled truss antenna flight experiment

    NASA Technical Reports Server (NTRS)

    Lee, W. H.

    1984-01-01

    The conceptual design for a scaled truss antenna structures experiment program (STASEP) is presented. The hardware analysis of the scaled truss antenna structure (STAS) was performed by interactive design and evaluation of advanced spacecraft (IDEAS) computer aided, interactive, design and analysis program. Four STAS's were designed to be launched by the Shuttle, tested by using the space technology experiments platform (STEP) and space transportation system (STS), and then free flown in short lifetime orbits. Data were gathered on deployment, structural characteristics, geometric accuracies, thermal performance, and drag and lifetime as an orbiting spacecraft. Structural and thermal properties were determined for the STAS, including mass properties, thermal loading, structural natural frequencies, and mode shapes. The necessary analysis, scaling, and ground testing are discussed.

  12. UHF Antenna Design for AFIT Random Noise Radar

    DTIC Science & Technology

    2012-03-01

    design for many different applications of varied band requirements, from narrowband to UWB . Also, the LPA is a proven design that has been used in a wide...the frequency band from 3.1 GHz – 10.6 GHz for unlicensed UWB applications in 2002 [3], there have been many new developments in UWB antenna...charges and alternating currents to electric and magnetic fields . Ampere’s Law (2) declares that an electric current causes a circulating magnetic field

  13. Design of an ICRF plasma thruster antenna by TOPICA

    NASA Astrophysics Data System (ADS)

    Vecchi, Giuseppe; Lancellotti, Vito; Maggiora, Riccardo

    2006-10-01

    A typical RF plasma thruster is comprised of an RF plasma source, an open-ended magnetic confinement device, an RF acceleration unit and a magnetic nozzle. The usual choice for the acceleration is to employ the Ion-Cyclotron resonance frequency (ICRF), a well established technology in fusion experiments for transferring large RF powers to magnetized plasmas. To help design RF thruster ICRF antennas, TOPICA (Torino Polytechnic Ion Cyclotron Antenna) code [1] has been recently extended to handle cylindrically symmetric plasmas. The latter entailed developing a wholly new module of TOPICA charged with the task of solving Maxwell's equations in cylindrical magnetized warm plasmas and yielding the Green's functionY (m,kz), i.e. the relationship at the air-plasma interface between the transverse magnetic and electric fields in the spectral (wavenumber) domain. The approach to the problem of determining the antenna input impedance relies on an integral-equation formulation for the self-consistent evaluation of the current distribution on the conductors. This work reports on TOPICA evolution and presents the design of an RF thruster ICRF antenna. *V. Lancellotti et al., Nucl. Fusion, 46 (2006) S476-S499

  14. Design and fabrication of microstrip antenna arrays

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A microstrip array project was conducted to demonstrate the feasibility of designing and fabricating simple, low cost, low sidelobe phased arrays with circular disk microstrip radiating elements. Design data were presented for microstrip elements and arrays including the effects of the protective covers, the mutual interaction between elements, and stripline feed network design. Low cost multilayer laminate fabrication techniques were also investigated. Utilizing this design data two C-band low sidelobe arrays were fabricated and tested: an eight-element linear and a sixty-four element planar array. These arrays incorporated stripline Butler matrix feed networks to produce a low sidelobe broadside beam.

  15. Shaped cassegrain reflector antenna. [design equations

    NASA Technical Reports Server (NTRS)

    Rao, B. L. J.

    1973-01-01

    Design equations are developed to compute the reflector surfaces required to produce uniform illumination on the main reflector of a cassegrain system when the feed pattern is specified. The final equations are somewhat simple and straightforward to solve (using a computer) compared to the ones which exist already in the literature. Step by step procedure for solving the design equations is discussed in detail.

  16. Shuttle antenna radome technology test program. Volume 2: Development of S-band antenna interface design

    NASA Technical Reports Server (NTRS)

    Kuhlman, E. A.; Baranowski, L. C.

    1977-01-01

    The effects of the Thermal Protection Subsystem (TPS) contamination on the space shuttle orbiter S band quad antenna due to multiple mission buildup are discussed. A test fixture was designed, fabricated and exposed to ten cycles of simulated ground and flight environments. Radiation pattern and impedance tests were performed to measure the effects of the contaminates. The degradation in antenna performance was attributed to the silicone waterproofing in the TPS tiles rather than exposure to the contaminating sources used in the test program. Validation of the accuracy of an analytical thermal model is discussed. Thermal vacuum tests with a test fixture and a representative S band quad antenna were conducted to evaluate the predictions of the analytical thermal model for two orbital heating conditions and entry from each orbit. The results show that the accuracy of predicting the test fixture thermal responses is largely dependent on the ability to define the boundary and ambient conditions. When the test conditions were accurately included in the analytical model, the predictions were in excellent agreement with measurements.

  17. Antennae

    NASA Image and Video Library

    1999-12-09

    Atlas Image mosaic, covering 7 x 7 on the sky of the interacting galaxies NGC 4038 and NGC 4039, better known as the Antennae, or Ring Tail galaxies. The two galaxies are engaged in a tug-of-war as they collide.

  18. Simple analysis and design of annular ring microstrip antennas

    NASA Astrophysics Data System (ADS)

    El-Khamy, S. E.; El-Awadi, R. M.; El-Sharrawy, E.-B. A.

    1986-06-01

    A simple analysis of thin annular-ring microstrip antennas (AR-MSA), along with a design technique that yields the optimum ring dimensions which maximizes the radiation efficiency and the bandwidth, is presented in this paper. Using the cavity model, exact closed form solutions for the radiation fields are derived. The antenna fields distribution, resonance dimensions, radiation patterns, directivity, radiation conductance, quality factor and bandwidth are investigated for the different TMnm modes. AR-MSAs operated at the high order TMn2 modes are found to have better radiation properties and broader bandwidths than the corresponding disk-MSAs. A design table for the optimum ring dimensions for different types of the dielectric substrate material is also given in the paper.

  19. New trends in antenna design: transformation optics approach

    NASA Astrophysics Data System (ADS)

    Tichit, P. H.; Burokur, S. N.; de Lustrac, A.

    2013-04-01

    Transformation optics is an emerging field offering a powerful and unprecedented ability to manipulate and control electromagnetic waves. Using this tool, we demonstrate the design of novel antenna concepts by tailoring their radiation properties. The wave manipulation is enabled through the use of engineered dispersive composite metamaterials that realize a space coordinate transformation. Numerical simulations together with experimental measurements are performed in order to validate the coordinate transformation concept. Near-field cartography and far-field pattern measurements performed on fabricated prototypes agree qualitatively with Finite Element Method (FEM) simulations. It is shown that a particular radiation pattern can be tailored at ease into a desired one by modifying the electromagnetic properties of the space around the radiating element. This idea opens the way to novel antenna design techniques for various application domains such as aeronautical and transport fields.

  20. Design of optical transmitting antenna with enhance performance in visible light communication

    NASA Astrophysics Data System (ADS)

    Kuang, Dang; Wang, Jianping; Lu, Huimin

    2016-10-01

    An optical transmitting antenna for visible light communication(VLC) is designed in this work, in which the antenna is positioned before the light-emitting diodes (LED) source to change the lighting distribution, in order to achieve uniform received power effect. The method to design antenna is introduced into physical optical lens principle. According to the energy conservation law and Snell law, the antenna is designed via establishing energy mapping between the luminous flux emitted by a LED source with Lambertian distribution and the target plane. The coordinates of the antenna model are obtained under matrix laboratory (MATLAB). The antenna model entity is generated through three dimensional (3D) composition software AutoCAD with the coordinates of antenna. Ray-tracing software Tracepro is used to trace the ray which through antenna, and validate the irradiance maps. The uniformity of illumination and received power of the designed VLC is improved from approximately 35% to over 83%.

  1. Design and Thermal Analysis for Space Deployable Antenna

    NASA Astrophysics Data System (ADS)

    Guan, Fu-Ling; Huang, Jiang; Zhang, Shu-Jie

    2002-01-01

    sensibility and thermal stability. But deployable antenna always enters into and leaves the earth shadow periodically when it orbits the earth, and it is affected by the shadows of itself Thus a key design for the antenna structure is to control its deformation in a limited range. Obviously, thermal analysis is very important for such structure to maintain its high thermal stability. of a supported backbone (deployable truss) and a reflector surface (flexible mesh). All analysis in this dissertation is based on this model, such as temperature field analysis, thermal deformation analysis, thermal stress analysis, thermal vibration analysis, and so on. tetrahedral element, is discussed. And the mechanism of spider nodes, middle nodes and torsion springs in these nodes are also illustrated. 6-node triangular membrane element are deduced. A temperature analysis procedure has been programmed. The obvious change in temperature happens when the antenna enter into the earth shadow, so this case should be studied to decide whether the temperature of the structure and its components are in the limited range or not. membrane element are put forward. According to the stiffness matrix of these elements and the structural equilibrium equations, thermal deformation and thermal stress of the structure can be computed. The results show that either the thermal deformation or the thermal stress is in the desired range, they have little effect on the shape and stiffness of the entire structure. vibration. The thermally vibration responses of the antenna are studied when it enters into the earth shadow from sunshine and when it enters into sunshine from the earth shadow. The results show that in both cases, there is no vibration in Y direction. The velocity and acceleration in X direction and Z direction are both small, but the displacement in X direction is large, the maximum is 6.5mm. Keyword: Deployable antenna; self-shadow; thermal deformation; thermal stress

  2. Next-generation tension strap supports for spaceborne dewars

    NASA Astrophysics Data System (ADS)

    Hopkins, R. A.; Payne, D. A.; Kriz, R. D.; Morris, E. E.

    1987-06-01

    In the design of long-life, spaceborne dewars the supports must be considered not only as a structural member, but also as part of the thermal isolation of the cold assembly. Filament-wound composite tension straps provide the strength needed for the launch environment while minimizing heat conduction into the dewar. The optimum material for this application has a large ratio of fatigue strength to thermal conductivity to miminize heat input and a high modulus of elasticity to maximize the system resonant frequency. The material that exhibits the best combination of these properties and has been used in numerous spaceborne dewars is fiberglass/epoxy. This paper presents measurements of mechanical and thermal properties of straps made of a newly-developed alumina fiber with epoxy resin. This composite has significantly higher fatigue strength and modulus of elasticity than fiberglass/epoxy and similar thermal conductivity. This material therefore appears to be the best available choice in the future for dewar tension strap supports. Heat input through the tension straps is also minimized by proper orientation within the dewar. Predictions of dewar thermal performance using lumina/epoxy straps and the improvement compared to a system using fiberglass/epoxy are presented for several relevant dewar applications. This new composite will likely become the material of choice for many future applications requiring structural support with maximum thermal isolation.

  3. Three-dimensional effects for radio frequency antenna modeling

    SciTech Connect

    Carter, M.D.; Batchelor, D.B.; Stallings, D.C. )

    1994-10-15

    Electromagnetic field calculations for radio frequency (rf) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. The 2-D calculations predict that the return currents in the sidewalls of the antenna structure depend strongly on the plasma parameters, but this prediction is suspect because of experimental evidence. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform three-dimensional (3-D) modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap and conducting sidewalls are considered. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven rf current to return in the antenna structure rather than the plasma, as in the 2-D model. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading predicted from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model, even with end-effect corrections for the 2-D model.

  4. Three-dimensional effects for radio frequency antenna modeling

    NASA Astrophysics Data System (ADS)

    Carter, M. D.; Batchelor, D. B.; Stallings, D. C.

    Electromagnetic field calculations for radio frequency (RF) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. The 2-D calculations predict that the return currents in the sidewalls of the antenna structure depend strongly on the plasma parameters, but this prediction is suspect because of experimental evidence. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform three-dimensional (3-D) modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap and conducting sidewalls are considered. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven RF current to return in the antenna structure rather than the plasma, as in the 2-D model. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading predicted from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model, even with end-effect corrections for the 2-D model.

  5. Three-dimensional effects for radio frequency antenna modeling

    NASA Astrophysics Data System (ADS)

    Carter, M. D.; Batchelor, D. B.; Stallings, D. C.

    1994-10-01

    Electromagnetic field calculations for radio frequency (rf) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. The 2-D calculations predict that the return currents in the sidewalls of the antenna structure depend strongly on the plasma parameters, but this prediction is suspect because of experimental evidence. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform three-dimensional (3-D) modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap and conducting sidewalls are considered. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven rf current to return in the antenna structure rather than the plasma, as in the 2-D model. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading predicted from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model, even with end-effect corrections for the 2-D model.

  6. The design and simulation test of wireless antenna protection network

    NASA Astrophysics Data System (ADS)

    Chen, Zipeng; Dai, Yawen; Li, Peng; Li, Zhuoqiu

    2013-03-01

    In this paper, a wireless antenna protection program has been designed. In the program, the TVS diode was used as the first lever for protection, and the π-type high pass filtering network as the second lever. As a result, the program not only has the traditional function of ESD protection, which can avoid the high voltage damage to the internal circuit, but also achieves the purpose of load matching, ensuring the signal source not to distort. The ADS simulation software was used to test the ability of this program for filtering and impedance matching, which proved the feasibility of this program. The wireless antenna protection network has been practically used, and its' performance of anti-electromagnetic interference has been validated.

  7. Antenna design and distribution of the LOFAR super station

    NASA Astrophysics Data System (ADS)

    Girard, Julien N.; Zarka, Philippe; Tagger, Michel; Denis, Laurent; Charrier, Didier; Konovalenko, Alexander A.; Boone, Frédéric

    2012-01-01

    The Nançay radio astronomy observatory and associated laboratories are developing the concept of a "Super Station" for extending the LOFAR station now installed and operational in Nançay. The LOFAR Super Station (LSS) will increase the number of high sensitivity long baselines, provide short baselines, act as an alternate core, and be a large standalone instrument. It will operate in the low frequency band of LOFAR (15-80 MHz) and extend this range to lower frequencies. Three key developments for the LSS are described here: (i) the design of a specific antenna, and the distribution of such antennas; (ii) at small-scale (analog-phased mini-array); and (iii) at large-scale (the whole LSS).

  8. Computer-aided design of antenna structures and components

    NASA Technical Reports Server (NTRS)

    Levy, R.

    1976-01-01

    This paper discusses computer-aided design procedures for antenna reflector structures and related components. The primary design aid is a computer program that establishes cross sectional sizes of the structural members by an optimality criterion. Alternative types of deflection-dependent objectives can be selected for designs subject to constraints on structure weight. The computer program has a special-purpose formulation to design structures of the type frequently used for antenna construction. These structures, in common with many in other areas of application, are represented by analytical models that employ only the three translational degrees of freedom at each node. The special-purpose construction of the program, however, permits coding and data management simplifications that provide advantages in problem size and execution speed. Size and speed are essentially governed by the requirements of structural analysis and are relatively unaffected by the added requirements of design. Computation times to execute several design/analysis cycles are comparable to the times required by general-purpose programs for a single analysis cycle. Examples in the paper illustrate effective design improvement for structures with several thousand degrees of freedom and within reasonable computing times.

  9. JPL-IDEAS - ITERATIVE DESIGN OF ANTENNA STRUCTURES

    NASA Technical Reports Server (NTRS)

    Levy, R.

    1994-01-01

    The Iterative DEsign of Antenna Structures (IDEAS) program is a finite element analysis and design optimization program with special features for the analysis and design of microwave antennas and associated sub-structures. As the principal structure analysis and design tool for the Jet Propulsion Laboratory's Ground Antenna and Facilities Engineering section of NASA's Deep Space Network, IDEAS combines flexibility with easy use. The relatively small bending stiffness of the components of large, steerable reflector antennas allows IDEAS to use pinjointed (three translational degrees of freedom per joint) models for modeling the gross behavior of these antennas when subjected to static and dynamic loading. This facilitates the formulation of the redesign algorithm which has only one design variable per structural element. Input data deck preparation has been simplified by the use of NAMELIST inputs to promote clarity of data input for problem defining parameters, user selection of execution and design options and output requests, and by the use of many attractive and familiar features of the NASTRAN program (in many cases, NASTRAN and IDEAS formatted bulk data cards are interchangeable). Features such as simulation of a full symmetric structure based on analyses of only half the structure make IDEAS a handy and efficient analysis tool, with many features unavailable in any other finite element analysis program. IDEAS can choose design variables such as areas of rods and thicknesses of plates to minimize total structure weight, constrain the structure weight to a specified value while maximizing a natural frequency or minimizing compliance measures, and can use a stress ratio algorithm to size each structural member so that it is at maximum or minimum stress level for at least one of the applied loads. Calculations of total structure weight can be broken down according to material. Center of gravity weight balance, static first and second moments about the center of

  10. Development of S-band antenna interface design, volume 1

    NASA Technical Reports Server (NTRS)

    Kuhlman, E. A.

    1976-01-01

    The construction of an analytical thermal model of an S-band antenna in a typical Space Shuttle Orbiter installation is discussed. The selection and modeling of orbital and entry thermal environment inputs for the thermal analyses are discussed. The results of analyses for a variety of orbital thermal environments and entry initial conditions are given. Design and fabrication details of a thermal test fixture which physically approximates the Orbiter installation are discussed. The design and fabrication of two electrical test fixtures which electrically simulate the Orbiter surface shape and thermal protection system are discussed.

  11. Convex controller design for vibration suppression of a flexible antenna

    SciTech Connect

    Leo, D.; Inman, D.

    1994-12-31

    A procedure based on convex optimization is used to design collocated control laws for a small-scale model of a flexible antenna. The objective of the active control is to minimize the response of a single rib to a disturbance occurring at a remote location on the structure. Two separate designs are examined. The first is standard Linear Quadratic Gaussian (LQG) control, whereby the H{sub 2} norm of the transfer matrix is minimized via the solution of two Riccati equations. Unfortunately, this type of design does not exploit the favorable attributes of sensor/actuator collocation, resulting in control laws that are not robust to model uncertainty and structural variations. An optimization approach to H{sub 2} optimal design is presented that bounds the phase of the control law, thereby increasing its robustness. The optimization is shown to be convex, providing important guarantees on solution accuracy and convergence. Control laws designed with both procedures are experimentally implemented on the antenna testbed. The results illustrate the advantages of designing H{sub 2} optimal controllers that are bounded in phase.

  12. Multiple Antenna Implementation System (MAntIS)

    SciTech Connect

    Carter, M.D.; Batchelor, D.B.; Jaeger, E.F.

    1993-01-01

    The MAntIS code was developed as an aid to the design of radio frequency (RF) antennas for fusion applications. The code solves for the electromagnetic fields in three dimensions near the antenna structure with a realistic plasma load. Fourier analysis is used in the two dimensions that are tangential to the plasma surface and backwall. The third dimension is handled analytically in a vacuum region with a general impedance match at the plasma-vacuum interface. The impedance tensor is calculated for a slab plasma using the ORION-lD code with all three electric field components included and warm plasma corrections. The code permits the modeling of complicated antenna structures by superposing currents that flow on the surfaces of rectangular parallelepipeds. Specified current elements have feeders that continuously connect the current flowing from the ends of the strap to the feeders. The elements may have an arbitrary orientation with respect to the static magnetic field. Currents are permitted to vary along the length of the current strap and feeders. Parameters that describe this current variation can be adjusted to approximately satisfy boundary conditions on the current elements. The methods used in MAntIS and results for a primary loop antenna design are presented.

  13. Multi-platform laser communication networking optical antenna system design

    NASA Astrophysics Data System (ADS)

    Zhang, Tao

    2016-10-01

    In this paper, a new conclusion based on rotating parabolic model and a different scheme of laser communication networking antenna system has been put forward in the paper. Based on rotating parabolic antenna, a new theory of the optical properties have been deduced, which can realize larger dynamic, duplex, networking communications among multiple platforms in 360° azimuth and pitch range. Meanwhile, depending on the operation mode of the system, multiple mathematical optimization models have been established. Tracking communication range, emission energy efficiency and receiving energy efficiency have been analyzed and optimized. Relationship among opening up and low apertures, the lens unit aperture, focal length of lens unit as well as rotating parabolic focal length have been analyzed. Tracking pitching range and emission energy utilization has carried on the theoretical derivation and optimization and networking platform link between energy receiver and transmitter has been analyzed. Taking some parameters of this new system into calculation, optimized results can be utilized with MATLAB software for its application and system of communication engineering. The rotating parabolic internal can form a hollow structure, which is utilized for miniaturization, light-weighted design and realize duplex communication in a wide range and distance. Circular orbit guidance is the modern way used in dynamic tracking system. The new theory and optical antenna system has widespread applications value as well.

  14. Structure design and mechanical measurement of inflatable antenna

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Guan, Fu-ling

    2012-07-01

    This paper deals with the initial shape analysis, cutting-pattern analysis, surface accuracy measurement and modal testing of high-precision inflatable antennas reflectors that are intended for spaceflight applications. The initial shape analysis method, formulated on the basis of membrane theory and elastic mechanics, determines the required as-manufactured shape of the reflective surface of the antenna reflector. On the other hand, the cutting-pattern analysis method, with its formulation based on spring-mass representations, numerically calculates the required cutting pattern of the planar membrane gores that are to be assembled to form the 3-dimensional reflective surface. To validate the effectiveness of the proposed analysis methods, a 3.2-m antenna reflector model was designed, manufactured, and assembled for ground demonstration and testing. The reflective surface accuracy of this demonstration reflector model was measured by a photogrammetric measuring system. Shape adjustments of the reflective surface were performed by systematically adjusting the tension in the cables that were used to mount the reflector to its support structure. It was found that the reflective surface accuracy of the reflector model, as defined by its RMS error from a best-fit parabolic shape, was less than 1 mm. In addition, dynamic and RF tests were also performed on the demonstration reflector model. The test results indicated that the first-mode frequency of the reflector model agreed well with the corresponding analytical prediction, and its radiation pattern was also well focused.

  15. Antennae

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Atlas Image mosaic, covering 7' x 7' on the sky of the interacting galaxies NGC 4038 and NGC 4039, better known as the Antennae, or Ring Tail galaxies. The two galaxies are engaged in a tug-of-war as they collide. The mutual gravitation between them is working to distort each spiral galaxy's appearance as the two merge. The interaction is evidently impetus for an intense burst of new star formation, as can be seen from the many infrared-bright knots and bright galactic nuclei. Compare the 2MASS view of this system with that obtained by the Hubble Space Telescope in the optical. Many of the same features are seen, although 2MASS is able to peer through much of the dust seen in the galaxies' disks. The galaxy light looks smoother. Also, in the near-infrared the bright knots of star formation are likely highlighted by the light of massive red supergiant stars. The much more extended 'tidal tails,' which give the Antennae their name, are quite faint in the 2MASS image mosaic.

  16. Strapping for temporomandibular joint dysfunction.

    PubMed

    Babu, Abraham Samuel; John, Sandhya Mary; Unni, Amith

    2008-01-01

    Temporomandibular joint dysfunction (TMJD) is a common problem seen in many of the dental clinics. Management of this depends on an accurate diagnosis of the cause for the TMJD. Physical therapy and rehabilitation play a vital role in the management of these dysfunctions. Physical therapy is useful in treating post-traumatic stiffness of the TMJ while strapping of the TMJ for a dysfunction along with conventional physical therapy is of benefit in terms of reduction in click, decrease in pain, and an improvement in function.

  17. Design and construction of prototype radio antenna for shortest radio wavelengths

    NASA Technical Reports Server (NTRS)

    Leighton, R. B.

    1975-01-01

    A paraboloid radio antenna of 10.4 meters diameter, 0.41 meter focal length was constructed and its successful completion is described. The surface accuracy of the antenna is at least four times better than any existing antenna in its class size (50 micrometers rms). Antenna design specifications (i.e., for mounting, drive motors, honeycomb structures) are discussed and engineering drawings and photographs of antenna components are shown. The antenna will be used for millimeter-wave interferometry and sub-millimeter wave radiometry over a full frequency range (up to approximately 860 GHz). The antenna will also be moveable (for interferometric use) between reinforced concrete pads by rail. The effects of the weather and gravity on antenna performance are briefly discussed.

  18. On-glass automotive diversity antenna and LNA design for S-band satellite digital radio

    NASA Astrophysics Data System (ADS)

    Yeğin, Korkut

    2015-11-01

    Selection combining diversity system with antennas mounted on windshield and backlite of a vehicle is proposed for satellite digital audio radio applications. Standalone exterior mount antennas on metallic vehicles perform well for satellite digital audio radio applications, but for composite body vehicles or interior mount antennas, antenna performance becomes a real issue. Proposed on-glass two-antenna diversity is one solution for such applications. The antenna correlation is calculated using the S-parameters of the antennas and found to be very low due to many wavelengths separation between the antennas. Design of low noise amplifier, which has sub 1 dB noise figure and good P1dB due to strong cellular signals, is also detailed. A diversity receiver is described and ride tests are performed to assess the performance of the diversity system in real-time, under weak satellite signal environment which is regarded as the most challenging reception condition.

  19. Design of the Vacuum Feedthrough for the EAST ICRF Antenna

    NASA Astrophysics Data System (ADS)

    Yang, Qingxi; Song, Yuntao; Wu, Songtao; Zhao, Yanping

    2011-04-01

    Detailed design of the vacuum feedthrough for the ion cyclotron radio frequency (ICRF) antenna in EAST, along with an electro-analysis and thermal structural analysis, is presented. The electric field, the voltage standing wave ratio (VSWR) and the stresses in the vacuum feedthrough are studied. A method using the rings of oxygen-free copper as the cushion and macro-beam plasma arc welding is applied in the assembly to protect the ceramic from being damaged during welding. The vacuum leak test on the prototype of vacuum feedthrough is introduced.

  20. Computer Aided Antenna Design and Frequency Selection for HF Communications.

    DTIC Science & Technology

    1984-06-01

    EESIGN ON THE ADPE-.- NIF (GREEN MACHINE) ... .... . . . . . . . 57 E. COMPUTER AIDED DESIGN USING ECAC1S ACCESSIBIE ANTENNA PACKAGE . . . . . . .. 57 F...8217 C8 L4 E-4 W 3a ’H 1 H -g I) - 4 ’ 0-4 =2 E-4 V. E-4 b. m 0 m 4 =- v- -4 3 4 E’- 4 = P4 H - ofC. I- 1 4 = W P4 w 4 I = N = V rq I 0-4 ~ to H W4

  1. Optics Design for the U.S. SKA Technology Development Project Design Verification Antenna

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Baker, L.; Cortes-Medellin, G.

    2012-01-01

    The U.S. design concept for the Square Kilometer Array (SKA) program is based on utilizing a large number of 15 meter dish antennas. The Technology Development Project (TDP) is planning to design and build the first of these antennas to provide a demonstration of the technology and a solid base on which to estimate costs. This paper describes the performance of the selected optics design. It is a dual-shaped offset Gregorian design with a feed indexer that can accommodate corrugated horns, wide band single pixel feeds or phased array feeds.

  2. Optics Design for the U.S. SKA Technology Development Project Design Verification Antenna

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Baker, L.; Cortes-Medellin, G.

    2012-01-01

    The U.S. design concept for the Square Kilometer Array (SKA) program is based on utilizing a large number of 15 meter dish antennas. The Technology Development Project (TDP) is planning to design and build the first of these antennas to provide a demonstration of the technology and a solid base on which to estimate costs. This paper describes the performance of the selected optics design. It is a dual-shaped offset Gregorian design with a feed indexer that can accommodate corrugated horns, wide band single pixel feeds or phased array feeds.

  3. Optical design of a synthetic aperture ladar antenna system

    NASA Astrophysics Data System (ADS)

    Cao, Changqing; Zeng, Xiaodong; Zhao, Xiaoyan; Liu, Huanhuan; Man, Xiangkun

    2008-03-01

    The spatial resolution of a conventional imaging LADAR system is constrained by the diffraction limit of the telescope aperture. The purpose of this work is to investigate Synthetic Aperture Imaging LADAR (SAIL), which employs aperture synthesis with coherent laser radar to overcome the diffraction limit and achieve fine-resolution, long range, two-dimensional imaging with modest aperture diameters. According to the demands of the Synthetic Aperture LADAR (SAL), the key techniques are analyzed briefly. The preliminary design of the optical antenna is also introduced in this paper. We investigate the design method and relevant problems of efficient optical antenna that are required in SAL. The design is pursued on the basis of the same method as is used at microwave frequency. The method is based on numerical analysis and the error values obtained by present manufacturing technology. According to the requirement to SAL with the trial of little size, light mass, low cost and high image quality, the result by ZEMAX will result.

  4. Design study of TDRS antenna gimbal system for LANDSAT-D

    NASA Technical Reports Server (NTRS)

    Wu, J.

    1977-01-01

    The conceptual design studies of a two axis antenna drive assembly for the TDRSS link communications subsystem for LANDSAT D are presented. The recommended antenna drive assembly is a simple and reliable design substantially similar to the antenna and solar array drives developed and space qualified for programs such as DSCS 2 and FltSatCom. The gimbal design tradeoff is presented, along with drive electronics.

  5. Evolutionary Design of an X-Band Antenna for NASA's Space Technology 5 Mission

    NASA Technical Reports Server (NTRS)

    Lohn, Jason D.; Hornby, Gregory S.; Rodriguez-Arroyo, Adan; Linden, Derek S.; Kraus, William F.; Seufert, Stephen E.

    2003-01-01

    We present an evolved X-band antenna design and flight prototype currently on schedule to be deployed on NASA s Space Technology 5 spacecraft in 2004. The mission consists of three small satellites that wall take science measurements in Earth s magnetosphere. The antenna was evolved to meet a challenging set of mission requirements, most notably the combination of wide beamwidth for a circularly-polarized wave and wide bandwidth. Two genetic algorithms were used: one allowed branching an the antenna arms and the other did not. The highest performance antennas from both algorithms were fabricated and tested. A handdesigned antenna was produced by the contractor responsible for the design and build of the mission antennas. The hand-designed antenna is a quadrifilar helix, and we present performance data for comparison to the evolved antennas. As of this writing, one of our evolved antenna prototypes is undergoing flight qualification testing. If successful, the resulting antenna would represent the first evolved hardware in space, and the first deployed evolved antenna.

  6. Design and optimization of LTE 1800 MIMO antenna.

    PubMed

    Wong, Huey Shin; Islam, Mohammad Tariqul; Kibria, Salehin

    2014-01-01

    A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide's outer shell. Isolation characteristics better than -15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz-1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi.

  7. Investigations of high power problems in space shuttle antenna designs

    NASA Technical Reports Server (NTRS)

    Taylor, W. C.; Alvares, N. J.

    1972-01-01

    A study program is discussed which includes a survey of industry and government laboratories and was undertaken to determine the state of the art in dealing with problems of high power levels in reentry antenna design. A laboratory program to develop techniques for testing dielectric materials for effects on RF transmission is also considered, with emphasis on high power applications in space and reentry flights. The study program resulted in a set of guidelines for avoiding breakdown in antenna design. A discussion of temperature effects on dielectric breakdown is also given. From the laboratory program, a description is presented of techniques for (1) heating with a carbon arc image furnace, (2) temperature measurement (using thermocouples and an infrared pyrometer), (3) mass spectrometric monitoring of outgassing, (4) testing for RF breakdown in both heated dielectrics and the dielectric/air and dielectric/plasma interfaces. Data and observations are reported from technique development using candidate shuttle materials falling into three categories: (1) lightweight refractory foams, (2) dense RF window materials, and (3) ablative materials.

  8. Thermal Strap And Cushion For Thermoelectric Cooler

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Petrick, S. Walter; Bard, Steven

    1991-01-01

    Inexpensive cushioning strap proposed for use as thermal contact between thermoelectric cooler and device to be cooled, such as laser diode, infrared detector, or charge-coupled device for imaging. Provides high thermal conductance while minimizing thermal and mechanical stresses on thermoelectric cooler. Used as alternative to flexible thermal strap made of silver.

  9. Multiple-Feed Design For DSN/SETI Antenna

    NASA Technical Reports Server (NTRS)

    Slobin, S. D.; Bathker, D. A.

    1988-01-01

    Frequency bands changed with little interruption of operation. Modification of feedhorn mounting on existing 34-m-diameter antenna in Deep Space Network (DSN) enables antenna to be shared by Search for Extra-Terrestrial Intelligence (SET) program with minimal interruption of DSN spacecraft tracking. Modified antenna useful in terrestrial communication systems requiring frequent changes of operating frequencies.

  10. Design investigation for a microstrip phased array antenna for the ORION satellite

    NASA Astrophysics Data System (ADS)

    Smith, Mark B.

    1988-06-01

    Students at the Naval Postgraduate School are designing a general purpose mini-satellite that can be launched from a Get-Away-Special cannister located in the cargo bay of the Space Shuttle and will be compatible with expendable launch vehicles as well. This thesis defines preliminary antenna systems and the design parameters for the telemetry system of the ORION mini-satellite. These antenna design parameters may be used for investigations of various proposed antenna systems and the design parameters also allow for trade-off studies with the mission capabilities and subsystems of the satellite. An investigation is made into the feasibility of using conformal microstrip patch array antennas for the telemetry, tracking and command (TT&C) systems. It is necessary to have two separate microstrip patch array antennas for the telemetry system: one uplink and one downlink antenna. The microstrip patch array antenna can operate as either an omnidirectional antenna or a directional antenna by changing the phase of the individual patch feeds. This feature gives the microstrip patch array antenna more flexibility for meeting the needs of potential users.

  11. Conceptual Design of the Aluminum Reflector Antenna for DATE5

    NASA Astrophysics Data System (ADS)

    Qian, Yuan; Kan, Frank W.; Sarawit, Andrew T.; Lou, Zheng; Cheng, Jing-Quan; Wang, Hai-Ren; Zuo, Ying-Xi; Yang, Ji

    2016-08-01

    DATE5, a 5 m telescope for terahertz exploration, was proposed for acquiring observations at Dome A, Antarctica. In order to observe the terahertz spectrum, it is necessary to maintain high surface accuracy in the the antenna when it is exposed to Antarctic weather conditions. Structural analysis shows that both machined aluminum and carbon fiber reinforced plastic (CFRP) panels can meet surface accuracy requirements. In this paper, one design concept based on aluminum panels is introduced. This includes panel layout, details on panel support, design of a CFRP backup structure, and detailed finite element analysis. Modal, gravity and thermal analysis are all performed and surface deformations of the main reflector are evaluated for all load cases. At the end of the paper, the manufacture of a prototype panel is also described. Based on these results, we found that using smaller aluminum reflector panels has the potential to meet the surface requirements in the harsh Dome A environment.

  12. Design and Measurement of Self-Matched, Dual-Frequency Coplanar-Waveguide-Fed Slot Antennas

    NASA Technical Reports Server (NTRS)

    Omar, Amjad A.; Scardelletti, Maxmilian C.; Hejazi, Zuhair M.; Dib, Nihad

    2007-01-01

    This report presents two new designs of dual-frequency, coplanar-waveguide-fed, double-folded slot antennas. An important advantage of these antennas is that, because they are self-matched to the feeding coplanar waveguide, they do not need an external matching circuit. This reduces the antenna size and simplifies its design. To verify the designs, the authors measured and compared the return loss and radiation patterns with those obtained using available commercial software with good agreement. Dual-frequency slot antennas;

  13. New designs for antenna-coupled superconducting bolometers

    SciTech Connect

    Mees, J.; Nahum, M.; Richards, P.L. )

    1991-10-28

    We propose a novel antenna-coupled low {ital T}{sub {ital c}} superconducting bolometer which makes use of the thermal boundary resistance and the trapping of quasiparticles at metal-superconducting interfaces. A thin strip of superconductor, whose temperature is regulated at the midpoint of its resistive transition, serves both as a resistive load to thermalize the infrared current from the antenna and as a thermometer to measure the resulting temperature rise. Calculations give a noise equivalent power (NEP){approx}7{times}10{sup {minus}16} {ital T}{sup 5/2} WHz{sup {minus}1/2} and a time constant {tau}{approx}10{sup {minus}8} {ital T}{sup {minus}2} s for a 2{times}2 {mu}m{sup 2} thermometer area at temperature {ital T} (K). Designs for efficient on-chip rf matching and filter networks with well-defined bandpasses are presented. These detectors can be used to make frequency-multiplexed array receivers for astronomical observations at near millimeter wavelengths.

  14. The Study and Implementation of Electrically Small Printed Antennas for an Integrated Transceiver Design

    SciTech Connect

    Speer, Pete

    2009-04-28

    This work focuses on the design and evaluation of the inverted-F, meandering-monopole, and loop antenna geometries. These printed antennas are studied with the goal of identifying which is suitable for use in a miniaturized transceiver design and which has the ability to provide superior performance using minimal Printed Circuit Board (PCB) space. As a result, the main objective is to characterize tradeoffs and identify which antenna provides the best compromise among volume, bandwidth and efficiency. For experimentation purposes, three types of meandering-monopole antenna are examined resulting in five total antennas for the study. The performance of each antenna under study is evaluated based upon return loss, operational bandwidth, and radiation pattern characteristics. For our purposes, return loss is measured using the S11-port reflection coefficient which helps to characterize how well the small antenna is able to be efficiently fed. Operational bandwidth is measured as the frequency range over which the antenna maintains 2:1 Voltage Standing Wave Ratio (VSWR) or equivalently has 10-dB return loss. Ansoft High Frequency Structure Simulator (HFSS) is used to simulate expected resonant frequency, bandwidth, VSWR, and radiation pattern characteristics. Ansoft HFSS simulation is used to provide a good starting point for antenna design before actual prototype are built using an LPKF automated router. Simulated results are compared with actual measurements to highlight any differences and help demonstrate the effects of antenna miniaturization. Radiation characteristics are measured illustrating how each antenna is affected by the influence of a non-ideal ground plane. The antenna with outstanding performance is further evaluated to determine its maximum range of communication. Each designs range performance is evaluated using a pair of transceivers to demonstrate round-trip communication. This research is intended to provide a knowledge base which will help

  15. Automatic antenna switching design for Extra Vehicular Activity (EVA) communication system

    NASA Technical Reports Server (NTRS)

    Randhawa, Manjit S.

    1987-01-01

    An Extra Vehicular Activity (EVA) crewmember had two-way communications with the space station in the Ku-band frequency (12 to 18 GHz). The maximum range of the EVA communications link with the space station is approximately one kilometer for nominal values for transmitter power, antenna gains, and receiver noise figure. The EVA Communications System, that will continue to function regardless of the astronaut's position and orientation, requires an antenna system that has full spherical coverage. Three or more antennas that can be flush mounted on the astronaut's space suit (EMU) and/or his propulsive backpack (MMU), will be needed to provide the desired coverage. As the astronaut moves in the space station, the signal received by a given EVA antenna changes. An automatic antenna switching system is needed that will switch the communication system to the antenna with the largest signal strength. A design for automatic antenna switching is presented and discussed.

  16. Designing of a small wearable conformal phased array antenna for wireless communications

    NASA Astrophysics Data System (ADS)

    Roy, Sayan

    In this thesis, a unique design of a self-adapting conformal phased-array antenna system for wireless communications is presented. The antenna system is comprised of one microstrip antenna array and a sensor circuit. A 1x4 printed microstrip patch antenna array was designed on a flexible substrate with a resonant frequency of 2.47 GHz. However, the performance of the antenna starts to degrade as the curvature of the surface of the substrate changes. To recover the performance of the system, a flexible sensor circuitry was designed. This sensor circuitry uses analog phase shifters, a flexible resistor and operational-amplifier circuitry to compensate the phase of each array element of the antenna. The proposed analytical method for phase compensation has been first verified by designing an RF test platform consisting of a microstrip antenna array, commercially available analog phase shifters, analog voltage attenuators, 4-port power dividers and amplifiers. The platform can be operated through a LabVIEW GUI interface using a 12-bit digital-to-analog converter. This test board was used to design and calibrate the sensor circuitry by observing the behavior of the antenna array system on surfaces with different curvatures. In particular, this phased array antenna system was designed to be used on the surface of a spacesuit or any other flexible prototype. This work was supported in part by the Defense Miroelectronics Activity (DMEA), NASA ND EPSCoR and DARPA/MTO.

  17. Comparison of different antenna designs in the spallation neutron source negative hydrogen ion source

    NASA Astrophysics Data System (ADS)

    Veitzer, Seth A.; Kundrapu, Madhusudhan; Stoltz, Peter H.; Beckwith, Kristian R. C.

    2017-08-01

    Internal antenna negative hydrogen ion sources can fail when plasma heating causes ablation of the insulating coating due to small structural defects such as cracks. During this process, plasma ions impacting the surfaces of rf antennas causes heating of the coating, which can melt or ablate, thus exposing conducting surfaces to the plasma. Reducing antenna failures that reduce the operating capabilities of the Spallation Neutron Source (SNS) accelerator has been one of the top priorities of the SNS H-Source Program at ORNL. We have been utilizing numerical modeling of internal antenna negative hydrogen ion sources in order help optimize antenna designs in order to reduce antenna failures. We have implemented a number of fluid models with electromagnetics using the simulation tool USim and applied them to modeling the SNS internal antenna negative ion source. We report here on results comparing two different antenna designs. The baseline design, as is currently in use in the SNS source, and a wide-leg design, that has been tested, and may replace the baseline design if it can reduce antenna failures while still maintaining source performance. The wide-leg antenna is designed to move the antenna supports out of the high-density plasma regions, in order to decrease the possible negative effects of ion bombardment. We model the plasma evolution using a single-fluid MHD model with an imposed magnetic field due to the rf antenna current and the confining multi-cusp field for both the baseline and wide-leg antenna configurations. We find that the maximum plasma velocity near the antenna surfaces is reduced by nearly 50% in the wide-leg configuration, and that overall the bulk plasma velocity is reduced for this configuration. In addition, although we measure a small increase in the maximum plasma flux on the antenna surface for the wide-leg design, we see a broad-based reduction of plasma flux on the antenna in the regions where the antenna is mostly exposed to the

  18. Spectral shaping and phase control of a fast-wave current drive antenna array

    SciTech Connect

    Baity, F.W.; Gardner, W.L.; Goulding, R.H.; Hoffman, D.J.; Ryan, P.M.

    1989-01-01

    The requirements for antenna design and phase control circuitry for a fast-wave current drive (FWCD) array operating in the ion cyclotron range of frequencies are considered. The design of a phase control system that can operate at arbitrary phasing over a wide range of plasma-loading and strap-coupling values is presented for a four-loop antenna array, prototypical of an array planned for the DIII-D tokamak (General Atomics, San Diego, California). The goal is to maximize the power launched with the proper polarization for current drive while maintaining external control of phase. Since it is desirable to demonstrate the feasibility of FWCD prior to ITER, a four-strap array has been designed for DIII-D to operate with the existing 2-MW transmitter at 60 MHz. 3 refs., 6 figs.

  19. Machine-Learning Approach for Design of Nanomagnetic-Based Antennas

    NASA Astrophysics Data System (ADS)

    Gianfagna, Carmine; Yu, Huan; Swaminathan, Madhavan; Pulugurtha, Raj; Tummala, Rao; Antonini, Giulio

    2017-08-01

    We propose a machine-learning approach for design of planar inverted-F antennas with a magneto-dielectric nanocomposite substrate. It is shown that machine-learning techniques can be efficiently used to characterize nanomagnetic-based antennas by accurately mapping the particle radius and volume fraction of the nanomagnetic material to antenna parameters such as gain, bandwidth, radiation efficiency, and resonant frequency. A modified mixing rule model is also presented. In addition, the inverse problem is addressed through machine learning as well, where given the antenna parameters, the corresponding design space of possible material parameters is identified.

  20. Design of highly efficient metallo-dielectric patch antennas for single-photon emission.

    PubMed

    Bigourdan, F; Marquier, F; Hugonin, J-P; Greffet, J-J

    2014-02-10

    Quantum emitters such as NV-centers or quantum dots can be used as single-photon sources. To improve their performance, they can be coupled to microcavities or nano-antennas. Plasmonic antennas offer an appealing solution as they can be used with broadband emitters. When properly designed, these antennas funnel light into useful modes, increasing the emission rate and the collection of single-photons. Yet, their inherent metallic losses are responsible for very low radiative efficiencies. Here, we introduce a new design of directional, metallo-dielectric, optical antennas with a Purcell factor of 150, a total efficiency of 74% and a collection efficiency of emitted photons of 99%.

  1. Radiofrequency magnetic resonance coils and communication antennas: Simulation and design strategies.

    PubMed

    Giovannetti, Giulio; Tiberi, Gianluigi

    2017-07-27

    Coils simulation and design is a fundamental task to maximize Signal-to-Noise Ratio in Magnetic Resonance applications. In the meantime, in the last years the issue of accurate communication antennas analysis has grown. Coil design techniques take advantage of computer simulations in dependence on the magnetic field wavelength and coil sizes. In particular, since at high frequencies coils start to behave as antennas, modern Magnetic Resonance coil development exploits numerical methods typically employed for antennas simulation. This paper reviews coil and antenna performance parameters and focuses on the different simulation approaches in dependence on the near/far field zones and operating frequency. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Large Antenna Multifrequency Microwave Radiometer (LAMMR) system design

    NASA Technical Reports Server (NTRS)

    King, J. L.

    1980-01-01

    The large Antenna Multifrequency Microwave Radiometer (LAMMR) is a high resolution 4 meter aperture scanning radiometer system designed to determine sea surface temperature and wind speed, atmospheric water vapor and liquid water, precipitation, and various sea ice parameters by interpreting brightness temperature images from low Earth orbiting satellites. The LAMMR with dual linear horizontal and vertical polarization radiometer channels from 1.4 to 91 GHZ can provide multidiscipline data with resolutions from 105 to 7 km. The LAMMR baseline radiometer system uses total power radiometers to achieve delta T's in the 0.5 to 1.7 K range and system calibration accuracies in the 1 to 2 deg range. A cold sky horn/ambient load two point calibration technique is used in this baseline concept and the second detector output uses an integrated and dump circuit to sample the scanning cross-tract resolution cells.

  3. Decentralized adaptive control designs and microstrip antennas for smart structures

    NASA Astrophysics Data System (ADS)

    Khorrami, Farshad; Jain, Sandeep; Das, Nirod K.

    1996-05-01

    Smart structures lend themselves naturally to a decentralized control design framework, especially with adaptation mechanisms. The main reason being that it is highly undesirable to connect all the sensors and actuators in a large structure to a central processor. It is rather desirable to have local decision-making at each smart patch. Furthermore, this local controllers should be easily `expandable' to `contractible.' This corresponds to the fact that addition/deletion of several smart patches should not require a total redesign of the control system. The decentralized control strategies advocated in this paper are of expandable/contractible type. On another front, we are considering utilization of micro-strip antennas for power transfer to and from smart structures. We have made preliminary contributions in this direction and further developments are underway. These approaches are being pursued for active vibration damping and noise cancellation via piezoelectric ceramics although the methodology is general enough to be applicable to other type of active structures.

  4. Large Antenna Multifrequency Microwave Radiometer (LAMMR) system design

    NASA Astrophysics Data System (ADS)

    King, J. L.

    1980-05-01

    The large Antenna Multifrequency Microwave Radiometer (LAMMR) is a high resolution 4 meter aperture scanning radiometer system designed to determine sea surface temperature and wind speed, atmospheric water vapor and liquid water, precipitation, and various sea ice parameters by interpreting brightness temperature images from low Earth orbiting satellites. The LAMMR with dual linear horizontal and vertical polarization radiometer channels from 1.4 to 91 GHZ can provide multidiscipline data with resolutions from 105 to 7 km. The LAMMR baseline radiometer system uses total power radiometers to achieve delta T's in the 0.5 to 1.7 K range and system calibration accuracies in the 1 to 2 deg range. A cold sky horn/ambient load two point calibration technique is used in this baseline concept and the second detector output uses an integrated and dump circuit to sample the scanning cross-tract resolution cells.

  5. Design of Miniaturized Dual-Band Microstrip Antenna for WLAN Application.

    PubMed

    Yang, Jiachen; Wang, Huanling; Lv, Zhihan; Wang, Huihui

    2016-06-27

    Wireless local area network (WLAN) is a technology that combines computer network with wireless communication technology. The 2.4 GHz and 5 GHz frequency bands in the Industrial Scientific Medical (ISM) band can be used in the WLAN environment. Because of the development of wireless communication technology and the use of the frequency bands without the need for authorization, the application of WLAN is becoming more and more extensive. As the key part of the WLAN system, the antenna must also be adapted to the development of WLAN communication technology. This paper designs two new dual-frequency microstrip antennas with the use of electromagnetic simulation software-High Frequency Structure Simulator (HFSS). The two antennas adopt ordinary FR4 material as a dielectric substrate, with the advantages of low cost and small size. The first antenna adopts microstrip line feeding, and the antenna radiation patch is composed of a folded T-shaped radiating dipole which reduces the antenna size, and two symmetrical rectangular patches located on both sides of the T-shaped radiating patch. The second antenna is a microstrip patch antenna fed by coaxial line, and the size of the antenna is diminished by opening a stepped groove on the two edges of the patch and a folded slot inside the patch. Simulation experiments prove that the two designed antennas have a higher gain and a favourable transmission characteristic in the working frequency range, which is in accordance with the requirements of WLAN communication.

  6. Design of Miniaturized Dual-Band Microstrip Antenna for WLAN Application

    PubMed Central

    Yang, Jiachen; Wang, Huanling; Lv, Zhihan; Wang, Huihui

    2016-01-01

    Wireless local area network (WLAN) is a technology that combines computer network with wireless communication technology. The 2.4 GHz and 5 GHz frequency bands in the Industrial Scientific Medical (ISM) band can be used in the WLAN environment. Because of the development of wireless communication technology and the use of the frequency bands without the need for authorization, the application of WLAN is becoming more and more extensive. As the key part of the WLAN system, the antenna must also be adapted to the development of WLAN communication technology. This paper designs two new dual-frequency microstrip antennas with the use of electromagnetic simulation software—High Frequency Structure Simulator (HFSS). The two antennas adopt ordinary FR4 material as a dielectric substrate, with the advantages of low cost and small size. The first antenna adopts microstrip line feeding, and the antenna radiation patch is composed of a folded T-shaped radiating dipole which reduces the antenna size, and two symmetrical rectangular patches located on both sides of the T-shaped radiating patch. The second antenna is a microstrip patch antenna fed by coaxial line, and the size of the antenna is diminished by opening a stepped groove on the two edges of the patch and a folded slot inside the patch. Simulation experiments prove that the two designed antennas have a higher gain and a favourable transmission characteristic in the working frequency range, which is in accordance with the requirements of WLAN communication. PMID:27355954

  7. A patch antenna design for application in a phased-array head and neck hyperthermia applicator.

    PubMed

    Paulides, Margarethus M; Bakker, Jurriaan F; Chavannes, Nicolas; Van Rhoon, Gerard C

    2007-11-01

    In this paper, we describe a specifically designed patch antenna that can be used as the basis antenna element of a clinical phased-array head and neck hyperthermia applicator. Using electromagnetic simulations we optimized the dimensions of a probe-fed patch antenna design for operation at 433 MHz. By several optimization steps we could converge to a theoretical reflection of -38 dB and a bandwidth (-15 dB) of 20 MHz (4.6%). Theoretically, the electrical performance of the antenna was satisfactory over a temperature range of 15 degrees C-35 degrees C, and stable for patient-antenna distances to as low as 4 cm. In an experimental cylindrical setup using six elements of the final patch design, we measured the impedance characteristics of the antenna 1) to establish its performance in the applicator and 2) to validate the simulations. For this experimental setup we simulated and measured comparable values: -21 dB reflection at 433 MHz and a bandwidth of 18.5 MHz. On the basis of this study, we anticipate good central interference of the fields of multiple antennas and conclude that this patch antenna design is very suitable for the clinical antenna array. In future research we will verify the electrical performance in a prototype applicator.

  8. Prototype 10-meter radio telescope antenna and mount design

    NASA Technical Reports Server (NTRS)

    Leighton, R. B.

    1976-01-01

    A prototype radio antenna of 10.4 meters diameter and 0.41 meter focal length, intended for use at the shortest radio wavelengths transmitted by the atmosphere, was successfully completed. The surface accuracy is at least four times better than that of any existing antenna in this size class: 50 micrometer rms. A prototype mount is being constructed and will be ready by early 1976. The development of an improved antenna of identical size, but heavier weight has been continued.

  9. Miniaturized Multi-Band Antenna Design via Element Collocation and Inductive Feed Loading

    SciTech Connect

    Martin, R. P.

    2012-09-12

    In a FY09 SDRD project, four separate antennas were designed to receive signals of interest covering a broad range of frequencies. While the elements exceeded specifications, the array footprint is substantial. Research performed by the CU Microwave Active Antenna Group in collaboration with RSL, showed promise in realizing a reduced structure. This work will expand upon this previous research. This project will result in a prototype quad-band antenna.

  10. Design and Optimization of Broadband High Impedance Ground Planes (HIGP) for Surface Mount Antennas

    DTIC Science & Technology

    2008-03-01

    materials, all of these material parameters are negative. With these unusual material parameters, new kinds of miniaturized antennas and microwave devices... ANTENNAS THESIS Murat Dogrul, First Lieutenant, TUAF AFIT/GE/ENG/08-08 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF...United States Government. AFIT/GE/ENG/08-08 DESIGN AND OPTIMIZATION OF BROADBAND HIGH IMPEDANCE GROUND PLANES (HIGP) FOR SURFACE MOUNT ANTENNAS

  11. The L-/C-band feed design for the DSS 14 70-meter antenna (Phobos mission)

    NASA Technical Reports Server (NTRS)

    Stanton, P. H.; Reilly, H. F., Jr.

    1991-01-01

    A dual-frequency (1.668 and 5.01 GHz) feed was designed for the Deep Space Station (DSS) 14 70-m antenna to support the Soviet Phobos Mission. This antenna system was capable of supporting telemetry, two-way Doppler, and very long baseline interferometry (VLBI). VLBI and two-way Doppler information on the Phobos spacecraft was acquired with this antenna in 1989.

  12. Precise antenna control design and its experimental verification

    NASA Astrophysics Data System (ADS)

    Kashiwase, Toshio; Yamada, Katsuhiko; Yamaguchi, Tetsuo; Awa, Yuji

    For inter-satellite communication, precise antenna pointing control with wide range and high scanning rate is required. Because structural vibration modes in the controller bandwidth degrade the performance of antenna pointing control and body attitude control, we need the antenna pointing control without excitation of the vibration modes. We propose here a new antenna control scheme with the function of active vibration control. Using a ground test setup, we verify the effectiveness of the control scheme as compared with the conventional proportional and integral (PI) control scheme.

  13. Efficient global optimization of a limited parameter antenna design

    NASA Astrophysics Data System (ADS)

    O'Donnell, Teresa H.; Southall, Hugh L.; Kaanta, Bryan

    2008-04-01

    Efficient Global Optimization (EGO) is a competent evolutionary algorithm suited for problems with limited design parameters and expensive cost functions. Many electromagnetics problems, including some antenna designs, fall into this class, as complex electromagnetics simulations can take substantial computational effort. This makes simple evolutionary algorithms such as genetic algorithms or particle swarms very time-consuming for design optimization, as many iterations of large populations are usually required. When physical experiments are necessary to perform tradeoffs or determine effects which may not be simulated, use of these algorithms is simply not practical at all due to the large numbers of measurements required. In this paper we first present a brief introduction to the EGO algorithm. We then present the parasitic superdirective two-element array design problem and results obtained by applying EGO to obtain the optimal element separation and operating frequency to maximize the array directivity. We compare these results to both the optimal solution and results obtained by performing a similar optimization using the Nelder-Mead downhill simplex method. Our results indicate that, unlike the Nelder-Mead algorithm, the EGO algorithm did not become stuck in local minima but rather found the area of the correct global minimum. However, our implementation did not always drill down into the precise minimum and the addition of a local search technique seems to be indicated.

  14. The Effect of a Backpack Hip Strap on Energy Expenditure While Walking.

    PubMed

    Pigman, Jamie; Sullivan, William; Leigh, Steven; Hosick, Peter A

    2017-09-01

    Objective To examine the effect of backpack hip strap use on walking energy expenditure while carrying a loaded backpack. Background Previous studies have demonstrated that energy cost increases as the mass of the load carried increases. However, few investigations have focused on backpack carriage design. Methods Fifteen young, healthy, male subjects walked at a self-selected pace for 10 minutes in two backpack loading conditions: with a hip strap (strapped) and without a hip strap (nonstrapped). Oxygen consumption (VO2), rating of perceived exertion (RPE), respiratory exchange ratio (RER), and heart rate (HR) were monitored throughout each 10-minute trial. Change scores from the 4th to 10th minute were calculated for each variable. A t test was used to evaluate the difference between conditions for each variable. Results The changes in VO2 (-0.62 ± 0.40 vs. 0.33 ± 0.23, p = .04) and RPE (1 ± 0.25 vs. 2 ± 0.21, p < .01) from the 4th to the 10th minute were different for the strapped versus nonstrapped condition. There was no difference in the change in RER (0.04 ± 0.01 vs. 0.03 ± 0.01, p > .05) or HR (3.53 ± 0.93 vs. 4.07 ± 1.39, p > .05) for the strapped versus unstrapped condition. Conclusions Wearing a hip strap reduced the energy expenditure and perceived exertion in as little as 10 minutes of walking compared to the nonstrapped condition. Future work should consider the effect of a hip strap on these variables while hiking for extended periods. Application Wearing a hip strap may increase the comfort and reduce the energy required of wearing a backpack. This is useful information for backpack designers, military personnel, and recreational hikers.

  15. Implanted miniaturized antenna for brain computer interface applications: analysis and design.

    PubMed

    Zhao, Yujuan; Rennaker, Robert L; Hutchens, Chris; Ibrahim, Tamer S

    2014-01-01

    Implantable Brain Computer Interfaces (BCIs) are designed to provide real-time control signals for prosthetic devices, study brain function, and/or restore sensory information lost as a result of injury or disease. Using Radio Frequency (RF) to wirelessly power a BCI could widely extend the number of applications and increase chronic in-vivo viability. However, due to the limited size and the electromagnetic loss of human brain tissues, implanted miniaturized antennas suffer low radiation efficiency. This work presents simulations, analysis and designs of implanted antennas for a wireless implantable RF-powered brain computer interface application. The results show that thin (on the order of 100 micrometers thickness) biocompatible insulating layers can significantly impact the antenna performance. The proper selection of the dielectric properties of the biocompatible insulating layers and the implantation position inside human brain tissues can facilitate efficient RF power reception by the implanted antenna. While the results show that the effects of the human head shape on implanted antenna performance is somewhat negligible, the constitutive properties of the brain tissues surrounding the implanted antenna can significantly impact the electrical characteristics (input impedance, and operational frequency) of the implanted antenna. Three miniaturized antenna designs are simulated and demonstrate that maximum RF power of up to 1.8 milli-Watts can be received at 2 GHz when the antenna implanted around the dura, without violating the Specific Absorption Rate (SAR) limits.

  16. Implanted Miniaturized Antenna for Brain Computer Interface Applications: Analysis and Design

    PubMed Central

    Zhao, Yujuan; Rennaker, Robert L.; Hutchens, Chris; Ibrahim, Tamer S.

    2014-01-01

    Implantable Brain Computer Interfaces (BCIs) are designed to provide real-time control signals for prosthetic devices, study brain function, and/or restore sensory information lost as a result of injury or disease. Using Radio Frequency (RF) to wirelessly power a BCI could widely extend the number of applications and increase chronic in-vivo viability. However, due to the limited size and the electromagnetic loss of human brain tissues, implanted miniaturized antennas suffer low radiation efficiency. This work presents simulations, analysis and designs of implanted antennas for a wireless implantable RF-powered brain computer interface application. The results show that thin (on the order of 100 micrometers thickness) biocompatible insulating layers can significantly impact the antenna performance. The proper selection of the dielectric properties of the biocompatible insulating layers and the implantation position inside human brain tissues can facilitate efficient RF power reception by the implanted antenna. While the results show that the effects of the human head shape on implanted antenna performance is somewhat negligible, the constitutive properties of the brain tissues surrounding the implanted antenna can significantly impact the electrical characteristics (input impedance, and operational frequency) of the implanted antenna. Three miniaturized antenna designs are simulated and demonstrate that maximum RF power of up to 1.8 milli-Watts can be received at 2 GHz when the antenna implanted around the dura, without violating the Specific Absorption Rate (SAR) limits. PMID:25079941

  17. Electromagnetic simulations of the ASDEX Upgrade ICRF Antenna with the TOPICA code

    SciTech Connect

    Krivska, A.; Milanesio, D.; Bobkov, V.; Braun, F.; Noterdaeme, J.-M.

    2009-11-26

    Accurate and efficient simulation tools are necessary to optimize the ICRF antenna design for a set of operational conditions. The TOPICA code was developed for performance prediction and for the analysis of ICRF antenna systems in the presence of plasma, given realistic antenna geometries. Fully 3D antenna geometries can be adopted in TOPICA, just as in available commercial codes. But while those commercial codes cannot operate with a plasma loading, the TOPICA code correctly accounts for realistic plasma loading conditions, by means of the coupling with 1D FELICE code. This paper presents the evaluation of the electric current distribution on the structure, of the parallel electric field in the region between the straps and the plasma and the computation of sheaths driving RF potentials. Results of TOPICA simulations will help to optimize and re-design the ICRF ASDEX Upgrade antenna in order to reduce tungsten (W) sputtering attributed to the rectified sheath effect during ICRF operation.

  18. Design of Vivaldi Microstrip Antenna for Ultra-Wideband Radar Applications

    NASA Astrophysics Data System (ADS)

    Perdana, M. Y.; Hariyadi, T.; Wahyu, Y.

    2017-03-01

    The development of radar technology has an important role in several fields such as aviation, civil engineering, geology, and medicine. One of the essential components of the radar system is the antenna. The bandwidth can specify the resolution of the radar. The wider the bandwidth, the higher the resolution of radar. For Ground penetrating radar (GPR) or medical applications need with a high-resolution radar so it needs an antenna with a wide bandwidth. In addition, for the radar application is required antenna with directional radiation pattern. So, we need an antenna with wide bandwidth and directional radiation pattern. One of antenna that has meet with these characteristics is vivaldi antenna. In previous research, has designed several vivaldi microstrip antenna for ultra-wideband radar applications which has a working frequency of 3.1 to 10.7 GHz. However, these studies there is still a shortage of one of them is the radiation pattern from lowest to highest frequency radiation pattern is not uniform in the sense that not all directional. Besides the antenna material used is also not easily available and the price is not cheap. This paper will discuss the design of a vivaldi microstrip antenna which has a wide bandwidth with directional radiation pattern works on 3.1 to 10.7 GHz and using cheaper substrate. Substrates used for vivaldi microstrip antenna vivaldi is FR4 with a dielectric constant of 4.3 and a thickness of 1.6 mm. Based on the simulation results we obtained that the antenna design has frequency range 3.1-10.7 GHz for return loss less than -10 dB with a directional radiation pattern. This antenna gain is 4.8 to 8 dBi with the largest dimension is 50 mm x 40 mm.

  19. Aircraft antennas/conformal antennas missile antennas

    NASA Astrophysics Data System (ADS)

    Solbach, Klaus

    1987-04-01

    Three major areas of airborne microwave antennas are examined. The basic system environment for missile telemetry/telecommand and fuze functions is sketched and the basic antenna design together with practical examples are discussed. The principle requirements of modern nose radar flat plate antennas are shown to result from missile/aircraft system requirements. Basic principles of slotted waveguide antenna arrays are sketched and practical antenna designs are discussed. The present early warning system designs are sketched to point out requirements and performance of practical radar warning and jamming antennas (broadband spiral antennas and horn radiators). With respect to newer developments in the ECM scenario, some demonstrated and proposed antenna systems (lens fed arrays, phased array, active array) are discussed.

  20. Polarizability tensor retrieval for magnetic and plasmonic antenna design

    NASA Astrophysics Data System (ADS)

    Bernal Arango, Felipe; Femius Koenderink, A.

    2013-07-01

    A key quantity in the design of plasmonic antennas and metasurfaces, as well as metamaterials, is the electrodynamic polarizability of a single scattering building block. In particular, in the current merging of plasmonics and metamaterials, subwavelength scatterers are judged by their ability to present a large, generally anisotropic electric and magnetic polarizability, as well as a bi-anisotropic magnetoelectric polarizability. This bi-anisotropic response, whereby a magnetic dipole is induced through electric driving, and vice versa, is strongly linked to the optical activity and chiral response of plasmonic metamolecules. We present two distinct methods to retrieve the polarizibility tensor from electrodynamic simulations. As a basis for both, we use the surface integral equation (SIE) method to solve for the scattering response of arbitrary objects exactly. In the first retrieval method, we project scattered fields onto vector spherical harmonics with the aid of an exact discrete spherical harmonic Fourier transform on the unit sphere. In the second, we take the effective current distributions generated by SIE as a basis to calculate dipole moments. We verify that the first approach holds for scatterers of any size, while the second is only approximately correct for small scatterers. We present benchmark calculations, revisiting the zero-forward scattering paradox of Kerker et al (1983 J. Opt. Soc. Am. 73 765-7) and Alù and Engheta (2010 J. Nanophoton. 4 041590), relevant in dielectric scattering cancelation and sensor cloaking designs. Finally, we report the polarizability tensor of split rings, and show that split rings will strongly influence the emission of dipolar single emitters. In the context of plasmon-enhanced emission, split rings can imbue their large magnetic dipole moment on the emission of simple electric dipole emitters. We present a split ring antenna array design that is capable of converting the emission of a single linear dipole emitter

  1. Designing and implementing Multibeam Smart Antennas for high bandwidth UAV communications using FPGAs

    NASA Astrophysics Data System (ADS)

    Porcello, J. C.

    Requirements for high bandwidth UAV communications are often necessary in order to move large amounts of mission information to/from Users in real-time. The focus of this paper is antenna beamforming for point-to-point, high bandwidth UAV communications in order to optimize transmit and receive power and support high data throughput communications. Specifically, this paper looks at the design and implementation of Multibeam Smart Antennas to implement antenna beamforming in an aerospace communications environment. The Smart Antenna is contrasted against Fast Fourier Transform (FFT) based beamforming in order to quantify the increase in both computational load and FPGA resources required for multibeam adaptive signal processing in the Smart Antenna. The paper begins with an overall discussion of Smart Antenna design and general beamforming issues in high bandwidth communications. Important design considerations such as processing complexity in a constrained Size, Weight and Power (SWaP) environment are discussed. The focus of the paper is with respect to design and implementation of digital beamforming wideband communications waveforms using FPGAs. A Multibeam Time Delay element is introduced based on Lagrange Interpolation. Design data for Multibeam Smart Antennas in FPGAs is provided in the paper as well as reference circuits for implementation. Finally, an example Multibeam Smart Antenna design is provided based on a Xilinx Virtex-7 FPGA. The Multibeam Smart Antenna example design illustrates the concepts discussed in the paper and provides design insight into Multibeam Smart Antenna implementation from the point of view of implementation complexity, required hardware, and overall system performance gain.

  2. Design, development and testing of the x-ray timing explorer High Gain Antenna System

    NASA Technical Reports Server (NTRS)

    Lecha, Javier; Woods, Claudia; Phan, Minh

    1995-01-01

    The High Gain Antenna System (HGAS), consisting of two High Gain Antenna Deployment Systems (HGADS) and two Antenna Pointing Systems (APS), is used to position two High Gain Antennas (HGA) on the X-Ray Timing Explorer (XTE). A similar APS will be used on the upcoming Tropical Rainfall Measuring Mission (TRMM). Both XTE and TRMM are NASA in-house satellites. The salient features of the system include the two-axis gimbal and control electronics of the APS and the spring deployment and latch/release mechanisms of the HGADS. This paper describes some of the challenges faced in the design and testing of this system and their resolutions.

  3. The Numerical Simulation of the Broadband Spiral Antenna Design Based on Hybrid Backed-Cavity

    NASA Astrophysics Data System (ADS)

    Liu, Chunheng; Lu, Yueguang; Du, Chunlei; Cui, Jingbo; Shen, Ximing

    2009-09-01

    In the paper, the hybrid backed-cavity with EBG (Electromagnetic Band-Gap) structure and PEC (Perfect Electronic Conductor) is proposed for Archimedean spiral antenna, which can make the spiral antenna work over the 10:1 bandwidth, without the loss introduced by absorbing materials. Based on the AMC characteristic (Artificial Magnetic Conductor), the EBG is placed in the outer region of backed-cavity to improve the blind spot gain in the low frequency. The PEC at the center of the structure is used to obtain high gain at high frequency. The better antenna performances are achieved in the low profile spiral antenna. A typical spiral antenna with hybrid backed cavity is numerically studied. The novel spiral antenna design with hybrid backed cavity is validated by simulated results.

  4. Bird Face Microstrip Printed Monopole Antenna Design for Ultra Wide Band Applications

    NASA Astrophysics Data System (ADS)

    Hossain, Mohammad Jakir; Faruque, Mohammad Rashed Iqbal; Islam, Md. Moinul; Islam, Mohammad Tariqul; Rahman, Md. Atiqur

    2016-11-01

    In this paper, a novel bird face microstrip printed monopole ultra-wideband (UWB) antenna is investigated. The proposed compact antenna consists of a ring-shaped with additional slot and slotted ground plane on FR4 material. The overall electrical dimension of the proposed antenna is 0.25 λ×0.36 λ×0.016 λ and is energized by microstrip feed line. The Computer Simulation Technology (CST) and the High Frequency Structural Simulator (HFSS) is applied in this analysis. The impedance bandwidth of the monopole antenna cover 3.1-12.3 GHz (9.2 GHz, BW) frequency range. The messurement displayed that the designed antenna achieved excellent gain and stable omnidirectional radiation patterns within the UWB. The maximum gain of 6.8 dBi and omnidirectional radiation pattern makes the proposed antenna that is suitable for UWB systems.

  5. Design and Experimental Implementation of Optimal Spacecraft Antenna Slews

    DTIC Science & Technology

    2013-12-01

    any spacecraft antenna configuration. Various software suites were used to perform thorough validation and verification of the Newton -Euler...verification of the Newton -Euler formulation developed herein. The antenna model was then utilized to solve an optimal control problem for a geostationary...DEVELOPING A MULTI-BODY DYNAMIC MODEL ........................................9  A.  THE NEWTON -EULER APPROACH

  6. Method of Making Steel Strapping and Strip

    SciTech Connect

    1999-12-10

    Fact sheet written for the Inventions and Innovation Program about a new method for making steel strapping and strip from rod stock produced from scrap steel. There is a large movement in the American steel industry to utilize more recycled steel. Recycled steel melted in the electric arc furnaces of mini-mills is being used as the source of raw materials for an increasing number of products, largely due to its lower price. However, conventional processes for producing steel strapping and cold-rolled strip steel restrict manufacturers from using more than 50% recycled steel. In addition, steel strapping and cold-rolled strip steel traditionally require many production steps. They are produced from primary steel that has been cast into slab, heated, rolled to achieve the desired thickness, and slit to the desired width. The slitting process produces microcracks along the edge of the strapping or strip, which reduce tensile strength. A new continuous process produces steel strapping and 1/2 inch to 6 inch strip steel from the rod and strip stock made from scrap steel in mini-mills. The new process creates steel strapping and strip with improved strength and quality due to the absence of microcracks caused by the conventional slitting process. The finished product is cheaper because of the lower cost associated with using rod ad lower conversion costs. In addition, the higher tensile strength of the product allows for thinner strapping. The process represents a new approach to producing any steel strapping used for bundling and packaging items for storage or transport. In addition, this innovative new process can be used to produce cold-rolled strip steel, a basic raw material for automobile parts, hardware, office equipment, and many other products.

  7. The design and fabrication of microstrip omnidirectional array antennas for aerospace applications

    NASA Technical Reports Server (NTRS)

    Campbell, T. G.; Appleton, M. W.; Lusby, T. K.

    1976-01-01

    A microstrip antenna design concept was developed that will provide quasi-omnidirectional radiation pattern characteristics about cylindrical and conical aerospace structures. L-band and S-band antenna arrays were designed, fabricated, and, in some cases, flight tested for rocket, satellite, and aircraft drone applications. Each type of array design is discussed along with a thermal cover design that was required for the sounding rocket applications.

  8. Performance and operational considerations in the design of vehicle antennas for mobile satellite communications

    NASA Technical Reports Server (NTRS)

    Milne, R.

    1995-01-01

    This paper examines the vehicle antenna requirements for mobile satellite systems. The antenna parameters are discussed in the light of the requirements and the limitations in performance imposed by the physical constraints of antenna and by vehicle geometries. Measurements of diffraction and antenna noise temperature in an operational environment are examined, as well as their effects on system margins. Mechanical versus electronic designs are compared with regards to performance, cost, reliability, and design complexity. Comparisons between open-loop and close-loop tracking systems are made and the effects of bandwidth, sidelobe levels, operational constraints, vehicle angular velocity, and acceleration are discussed. Some consideration is given to the use of hybrid systems employing both open and closed-loop tracking. Changes to antenna/terminal specifications are recommended which will provide greater design flexibility and increase the likelihood of meeting the performance and operational requirements.

  9. Quasi-optical antenna-mixer-array design for terahertz frequencies

    NASA Technical Reports Server (NTRS)

    Guo, Yong; Potter, Kent A.; Rutledge, David B.

    1992-01-01

    A new quasi-optical antenna-mixer-array design for terahertz frequencies is presented. In the design, antenna and mixer are combined into an entity, based on the technology in which millimeter-wave horn antenna arrays have been fabricated in silicon wafers. It consists of a set of forward- and backward-looking horns made with a set of silicon wafers. The front side is used to receive incoming signal, and the back side is used to feed local oscillator signal. Intermediate frequency is led out from the side of the array. Signal received by the horn array is picked up by antenna probes suspended on thin silicon-oxynitride membranes inside the horns. Mixer diodes will be located on the membranes inside the horns. Modeling of such an antenna-mixer-array design is done on a scaled model at microwave frequencies. The impedance matching, RF and LO isolation, and patterns of the array have been tested and analyzed.

  10. System and antenna design considerations for highly elliptical orbits as applied to the proposed Archimedes Constellation

    NASA Technical Reports Server (NTRS)

    Paynter, C.; Cuchanski, M.

    1995-01-01

    The paper discusses various aspects of the system design for a satellite in a highly elliptical inclined orbit, and presents a number of antenna design options for the proposed Archimedes mission. A satellite constellation was studied for the provision of multi media communication services in the L and S Band for northern latitudes. The inclined elliptical orbit would allow coverage of Europe, America, and East Asia. Using Canada and North America as the baseline coverage area, this paper addresses system considerations such as the satellite configuration and pointing, beam configuration, and requirements for antennas. A trade-off is performed among several antenna candidates including a direct radiating array, a focal-fed reflector, and a single reflector imaging system. Antenna geometry, performance, and beam forming methods are described. The impact of the designs on the antenna deployment is discussed.

  11. System and antenna design considerations for highly elliptical orbits as applied to the proposed Archimedes Constellation

    NASA Technical Reports Server (NTRS)

    Paynter, C.; Cuchanski, M.

    1995-01-01

    The paper discusses various aspects of the system design for a satellite in a highly elliptical inclined orbit, and presents a number of antenna design options for the proposed Archimedes mission. A satellite constellation was studied for the provision of multi media communication services in the L and S Band for northern latitudes. The inclined elliptical orbit would allow coverage of Europe, America, and East Asia. Using Canada and North America as the baseline coverage area, this paper addresses system considerations such as the satellite configuration and pointing, beam configuration, and requirements for antennas. A trade-off is performed among several antenna candidates including a direct radiating array, a focal-fed reflector, and a single reflector imaging system. Antenna geometry, performance, and beam forming methods are described. The impact of the designs on the antenna deployment is discussed.

  12. Quasi-isotropic VHF antenna array design study for the International Ultraviolet Explorer satellite

    NASA Technical Reports Server (NTRS)

    Raines, J. K.

    1975-01-01

    Results of a study to design a quasi-isotropic VHF antenna array for the IUE satellite are presented. A free space configuration was obtained that has no nulls deeper than -6.4 dbi in each of two orthogonal polarizations. A computer program named SOAP that analyzes the electromagnetic interaction between antennas and complicated conducting bodies, such as satellites was developed.

  13. Design and rigorous analysis of generalized axially- symmetric dual-reflector antennas

    NASA Astrophysics Data System (ADS)

    Moreira, Fernando J. S.

    1997-10-01

    The development of reflector antennas is continuously driven by ever increasing performance requirements, creating a demand for improved design and analysis tools. Ideally, the antenna synthesis should rely on general closed-form design equations (to establish the initial geometry and performance), as well as on accurate analysis techniques (to tune up the antenna performance by accounting for all pertinent electrical effects). Driven by these motivations, this dissertation provides the required formulation for the rigorous (in a numerical sense) analysis of axially-symmetric dual-reflector antennas and for their effective design. The rigorous analysis is performed using integral-equation techniques, which permit the inclusion of all relevant antenna components (i.e., reflector surfaces and feed structure), with the exception of the supporting struts and radomes. These techniques allow the electrical performance of a designed antenna to be accurately determined, hence minimizing the use of hardware models. The design portion starts with a unified investigation of generalized classical axially-symmetric dual-reflector antennas- conic-section generated configurations that minimize the main-reflector scattering towards the subreflector while providing a uniform-phase aperture illumination. It is shown that all possible configurations can be grouped in four basic categories. Using Geometrical Optics principles, useful closed-form design expressions are obtained, allowing a straightforward determination of the initial geometry and its upper-bound high-frequency performance. The improvement of the antenna radiation characteristics through the reflector shaping is also explored. An amplitude distribution is proposed for the shaped-antenna aperture field (with constant phase), providing high efficiency while controlling the sidelobe envelope. The diffraction and spillover effects are also investigated using Geometrical Theory of Diffraction, yielding useful formulas and

  14. Three-dimensional effects for radio frequency antenna modeling

    SciTech Connect

    Carter, M.D.; Batchelor, D.B.; Stallings, D.C.

    1993-09-01

    Electromagnetic field calculations for radio frequency (rf) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. Comparisons with experiments indicate that these 2-D calculations can overestimate the loading of the antenna and fail to give the correct reactive behavior. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform 3-D modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap, conducting sidewalls, and finite phase velocity are considered. The plasma impedance matrix for the loading calculation is generated by use of the ORION-1D code. The 3-D model is benchmarked with the 2-D model in the 2-D limit. For finite-length antennas, inductance calculations are found to be in much more reasonable agreement with experiments for 3-D modeling than for the 2-D estimates. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven rf current to return in the antenna sidewalls rather than in the plasma as in the 2-D model. Thus, the feeders have much more influence than the plasma on the currents that return in the sidewall. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model.

  15. Three-dimensional effects for radio frequency antenna modeling

    NASA Astrophysics Data System (ADS)

    Carter, M. D.; Batchelor, D. B.; Stallings, D. C.

    1993-09-01

    Electromagnetic field calculations for radio frequency (RF) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. Comparisons with experiments indicate that these 2-D calculations can overestimate the loading of the antenna and fail to give the correct reactive behavior. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform 3-D modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap, conducting sidewalls, and finite phase velocity are considered. The plasma impedance matrix for the loading calculation is generated by use of the ORION-1D code. The 3-D model is benchmarked with the 2-D model in the 2-D limit. For finite-length antennas, inductance calculations are found to be in much more reasonable agreement with experiments for 3-D modeling than for the 2-D estimates. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven RF current to return in the antenna sidewalls rather than in the plasma as in the 2-D model. Thus, the feeders have much more influence than the plasma on the currents that return in the sidewall. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model.

  16. Design and implementation of dual-band antennas based on a complementary split ring resonators

    NASA Astrophysics Data System (ADS)

    Ortiz, Noelia; Iriarte, Juan Carlos; Crespo, Gonzalo; Falcone, Francisco

    2015-07-01

    A simple dual-band antenna design and implementation method is proposed in this work, based on the equivalent media properties inspired by resonant metamaterial elements. The equivalent circuit model of dual-band patch antennas based on a complementary split ring resonator (CSRR) is presented and validated. The dual-band patch antenna is designed etching a CSRR in the patch of a conventional rectangular microstrip patch antenna. The first resonance is governed by the quasi-static resonance of the CSRR while the second resonance is originated by the rectangular patch. The fact of etching a CSRR on a rectangular patch antenna also produces a miniaturization of a conventional patch antenna. The equivalent circuit model proposed in this letter is sound in order to understand the functionality of dual-band patch antennas based on a CSRR. Good agreement between simulation, equivalent circuit model and experimental results is shown and discussed. These results lead the equivalent circuit model to become a simple and straightforward tool for the design of this type of multiband antennas, of low cost and versatile operation for a broad range of wireless communication systems.

  17. Consequences of antenna design in telemetry studies of small passerines

    USGS Publications Warehouse

    Dougill, Steve J.; Johnson, Luanne; Banko, Paul C.; Goltz, Dan M.; Wiley, Michael R.; Semones, John D.

    2000-01-01

    Entanglement and mortality of Palila (Loxioides bailleui), an endangered Hawaiian honeycreeper, occurred when birds were radio-tagged with transmitters equipped with a long, limp, solder-tipped antenna. Birds were found suspended in trees by their transmitter antenna on eight occasions. Although these birds eventually freed themselves or were freed by us, at least one bird died afterwards. For radio telemetry studies of small passerine species we recommend avoiding transmitters equipped with an antenna that is bulbous at the tip, >16 cm in length, limp, and shiny.

  18. Design and Sizing of a 40M2 Deployable Membrane SAR Space Antenna

    NASA Astrophysics Data System (ADS)

    Straubel, Marco; Huhne, Christian; Arlt, Christine; Langlois, Stephane; Sinapius, Michael

    2012-07-01

    As there is still a demand for large SAR apertures for L and P-band, DLR and ESA decide in 2007 to start a collaborative study on VERY LARGE STABLE MEMBRANE ANTENNA ARCHITECTURES that is focussed on gossamer structures. The results of this study are shown in the paper. It contains a brief discussion on available conventional and gossamer antenna designs and introduces the elaborated design of our study. In addition, the sizing of the antenna parts is presented in extracts. An automated sizing approach involving routines in MATLAB and ANSYS is introduces that performs an autonomous sizing of such antenna structure for launch and operation loads within a time frame of about 8 minutes. Finally, this automatic sizing approach is used to do a parameter study and show the consequence of changed requirements or antenna membrane specification on the over all mass and mass spreading.

  19. Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags.

    PubMed

    Rokunuzzaman, Md; Islam, Mohammad Tariqul; Rowe, Wayne S T; Kibria, Salehin; Jit Singh, Mandeep; Misran, Norbahiah

    2016-01-01

    A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919-923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for 'place and tag' application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP).

  20. Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags

    PubMed Central

    Islam, Mohammad Tariqul; Rowe, Wayne S. T.; Kibria, Salehin; Jit Singh, Mandeep; Misran, Norbahiah

    2016-01-01

    A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919–923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for ‘place and tag’ application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP). PMID:27533470

  1. Project Report: Design and Analysis for the Deep Space Network BWG Type 2 Antenna Feed Platform

    NASA Technical Reports Server (NTRS)

    Crawford, Andrew

    2011-01-01

    The following report explains in detail the solid modeling design process and structural analysis of the LNA (Low Noise Amplifier) feed platform to be constructed and installed on the new BWG (Beam Wave Guide) Type-2 tracking antenna in Canberra, Australia, as well as all future similar BWG Type-2 antennas builds. The Deep Space Networks new BWG Type-2 antennas use beam waveguides to funnel and 'extract' the desired signals received from spacecraft, and the feed platform supports and houses the LNA(Low Noise Amplifier) feed-cone and cryogenic cooling equipment used in the signal transmission and receiving process. The mandated design and construction of this platform to be installed on the new tracking antenna will be used and incorporated on all future similar antenna builds.

  2. Project Report: Design and Analysis for the Deep Space Network BWG Type 2 Antenna Feed Platform

    NASA Technical Reports Server (NTRS)

    Crawford, Andrew

    2011-01-01

    The following report explains in detail the solid modeling design process and structural analysis of the LNA (Low Noise Amplifier) feed platform to be constructed and installed on the new BWG (Beam Wave Guide) Type-2 tracking antenna in Canberra, Australia, as well as all future similar BWG Type-2 antennas builds. The Deep Space Networks new BWG Type-2 antennas use beam waveguides to funnel and 'extract' the desired signals received from spacecraft, and the feed platform supports and houses the LNA(Low Noise Amplifier) feed-cone and cryogenic cooling equipment used in the signal transmission and receiving process. The mandated design and construction of this platform to be installed on the new tracking antenna will be used and incorporated on all future similar antenna builds.

  3. Plasmonic antennas as design elements for coherent ultrafast nanophotonics

    PubMed Central

    Brinks, Daan; Castro-Lopez, Marta; Hildner, Richard; van Hulst, Niek F.

    2013-01-01

    Broadband excitation of plasmons allows control of light-matter interaction with nanometric precision at femtosecond timescales. Research in the field has spiked in the past decade in an effort to turn ultrafast plasmonics into a diagnostic, microscopy, computational, and engineering tool for this novel nanometric–femtosecond regime. Despite great developments, this goal has yet to materialize. Previous work failed to provide the ability to engineer and control the ultrafast response of a plasmonic system at will, needed to fully realize the potential of ultrafast nanophotonics in physical, biological, and chemical applications. Here, we perform systematic measurements of the coherent response of plasmonic nanoantennas at femtosecond timescales and use them as building blocks in ultrafast plasmonic structures. We determine the coherent response of individual nanoantennas to femtosecond excitation. By mixing localized resonances of characterized antennas, we design coupled plasmonic structures to achieve well-defined ultrafast and phase-stable field dynamics in a predetermined nanoscale hotspot. We present two examples of the application of such structures: control of the spectral amplitude and phase of a pulse in the near field, and ultrafast switching of mutually coherent hotspots. This simple, reproducible and scalable approach transforms ultrafast plasmonics into a straightforward tool for use in fields as diverse as room temperature quantum optics, nanoscale solid-state physics, and quantum biology. PMID:24163355

  4. Design and synthesis of flexible switching 1 × 2 antenna array on Kapton substrate

    NASA Astrophysics Data System (ADS)

    Georges Rabobason, Yvon; Rigas, Grigorios; Swaisaenyakorn, Srijittar; Mirkhaydarov, Bobur; Ravelo, Blaise; Shkunov, Maxim; Young, Paul; Benjelloun, Nabil

    2016-06-01

    Flexible front- and back-end RF/analogue system antennas were recently emerged. However, little flexible antenna system design is available so far, in planar hybrid technology with surface mounted components. This paper describes the design feasibility of flexible switching 1 × 2 antenna array system. It acts as a switching antenna implemented in hexapole configuration. The system is comprised of a key element RF switch terminated by two identical patch antennas associated to half-wave elementary transmission lines (TLs). A detailed theory illustrating the global S-parameter model determination in function of the given RF-switch return and insertion losses is established. In difference to the conventional microwave circuit theory, the proposed equivalent S-parameter model is originally built with the non-standard optimized antenna load. Thus, the synthesis method of the terminal antenna input impedance and the output access line characteristic impedance is formulated in function of the specified return and optimal transmission losses. The design method and theoretical approach feasibility is verified with the demonstrator of flexible switching 1 × 2 antenna array printed on Kapton substrate. The circuit prototype is implemented in hybrid planar technology integrating patch antenna operating at about 6 GHz and a packaged GaAs RF switch associated to the RF/DC signal decoupling accessory mounted surface components. Simulations of the designed circuit transmission and isolation losses from 5.5 GHz to 7 GHz were carried out by using the commercial RF switch S-parameter touchstone model provided by the manufacturer. The simulated and measured return losses are compared and discussed. Then, the measured radiation patterns confirm the proposed switched antenna concept feasibility.

  5. Analysis, design and implementation of Front-End Reconfigurable Antenna Systems (FERAS)

    NASA Astrophysics Data System (ADS)

    Tawk, Youssef Antoine

    2011-12-01

    The increase in demand on reconfigurable systems and especially for wireless communications applications has stressed the need for smart and agile RF devices that sense and respond to the RF changes in the environment. Many different applications require frequency agility with software control ability such as in a cognitive radio environment where antenna systems have to be designed to fulfill the extendable and reconfigurable multi-service and multi-band requirements. Such applications increase spectrum efficiency as well as the power utilization in modern wireless systems. The emphasis of this dissertation revolves around the following question: "Is it possible to come up with new techniques to achieve reconfigurable antenna systems with better performance?" Two main branches constitute the outline of this work. The first one is based on the design of reconfigurable antennas by incorporating photoconductive switching elements in order to change the antenna electrical properties. The second branch relies on the change in the physical structure of the antenna via a rotational motion. In this work a new photoconductive switch is designed with a new light delivery technique. This switch is incorporated into new optically pumped reconfigurable antenna systems (OPRAS). The implementation of these antenna systems in applications such as cognitive radio is demonstrated and discussed. A new radio frequency (RF) technique for measuring the semiconductor carrier lifetime using optically reconfigurable transmission lines is proposed. A switching time investigation for the OPRAS is also accomplished to better cater for the cognitive radio requirements. Moreover, different reconfiguration mechanisms are addressed such as physical alteration of antenna parts via a rotational motion. This technique is supported by software to achieve a complete controlled rotatable reconfigurable cognitive radio antenna system. The inter-correlation between neural networks and cellular automata

  6. Investigation of 'Conjugate T' Load-Resilient ICRF Antenna Systems - Application to the JET ITER-Like and to a Possible ITER ICRF System

    SciTech Connect

    Lamalle, P.U.; Messiaen, A.M.; Dumortier, P.; Durodie, F.; Evrard, M.; Louche, F.; Vervier, M.; Weynants, R.

    2005-09-26

    The paper reports on the radio-frequency (RF) analysis of multiple-short-strap load-resilient ICRF antenna systems, applied to the JET ITER-Like and to a proposed ITER ICRF system. The short radiating straps minimize the antenna voltage and the 'conjugate T' load resilient matching circuit aims at reliable power delivery to ELMy H mode plasmas. The two designs mainly differ by the use of in-vessel matching capacitors for the JET array, whereas the proposed ITER design uses an optimized combination of straps in parallel and ex-vessel matching by means of line stretchers. Asymmetries and mutual coupling between straps strongly influence the performance of such load-resilient circuits and complicate their operation. These effects have been analyzed in detail along two parallel lines of investigation: (i) Detailed RF simulations, in which the input impedance matrix of the ICRF arrays has been computed with a three-dimensional electromagnetic code and incorporated in realistic models of the transmission and matching circuits, (ii) Comprehensive RF measurements on a scaled-down mockup of the proposed ITER antenna. Ongoing work to optimize array performance and to develop practical matching procedures and reliable automatic control of the matching elements is discussed. The main outstanding issues are reliable arc detection and demonstration of a robust array control algorithm.

  7. Scheduling and Topology Design in Networks with Directional Antennas

    DTIC Science & Technology

    2017-05-19

    2006. [2] A. Alexiou and M. Haardt, “Smart Antenna Technologies for Future Wire- less Systems: Trends and Challenges.” IEEE Communications Magazine...Shen, “Multibeam antenna-based topology control with directional power intensity for ad hoc networks, IEEE Trans. Mobile Computing, vol. 5, no. 5...5] V. Namboodiri, L. Gao, and R. Janaswamy, “Power Efficient Topology Control for Wireless Networks with Switched Beam Directional Anten- nas, IEEE

  8. On the design of large space deployable modular antenna reflectors

    NASA Technical Reports Server (NTRS)

    Ribble, J. W.; Woods, A. A., Jr.

    1981-01-01

    The deployment kinematics, stowing philosophy, and deployment sequencing for large deployable antenna modules were verified. Mesh attachment methods compatible with full scale modules were devised. Parametric studies of large modular reflectors established size, mass, and aperture frequency capabilities for these assemblies. Preliminary studies were made devising means of delivering modules to orbit, and once there, of assembling the modules into complete modular antenna reflectors. The basic feasibility of creating mass efficient modules erectable into large structures in space was established.

  9. Design of a 60 GHz beam waveguide antenna positioner

    NASA Technical Reports Server (NTRS)

    Emerick, Kenneth S.

    1989-01-01

    A development model antenna positioner mechanism with an integral 60 GHz radio frequency beam waveguide is discussed. The system features a 2-ft diameter carbon-fiber reinforced epoxy antenna reflector and support structure, and a 2-degree-of-freedom elevation over azimuth mechanism providing hemispherical field of view. Emphasis is placed on the constraints imposed on the mechanism by the radio frequency subsystems and how they impacted the mechanical configuration.

  10. Design of a wide-gain-bandwidth metasurface antenna at terahertz frequency

    NASA Astrophysics Data System (ADS)

    Hussain, Niamat; Park, Ikmo

    2017-05-01

    This paper presents the design of a planar low-profile, wide-gain-bandwidth metasurface antenna at terahertz frequency. The proposed antenna consists of a metasurface and a planar feeding structure, both of which are patterned on an electrically thin, high-permittivity GaAs substrate. The metasurface, which is printed on the top of the substrate, consists of a periodic array of 5×5 square patches, while the planar feeding structure, which is printed on the bottom of the substrate, is a wideband, leaky-wave, open-ended slotline, which is fed at the center. The antenna with a single feeding structure showed a maximum broadside gain of 9.8 dBi, a radiation efficiency of 69%, and a 3-dB gain bandwidth of 16% (0.34-0.4 THz). The antenna gain performance was significantly improved by exciting the antenna with an array of slit feeding and without changing the antenna size. The antenna with a multiple (five) feeding structure showed a gain of 15.5 dBi, a 3-dB gain bandwidth of 17.3%, and a radiation efficiency of 73%. This antenna achieved a size reduction of 31 times in terms of device thickness in comparison with the design of the lens coupled antenna while achieving a comparable gain. In addition to its high gain and wide-gain-bandwidth characteristics, the proposed antenna design exhibits a low-profile mechanical robustness, easy integration into circuit boards, and excellent low-cost mass production suitability.

  11. Structural design of a vertical antenna boresight 18.3 by 18.3-m planar near-field antenna measurement system

    NASA Astrophysics Data System (ADS)

    Sharp, G. R.; Trimarchi, P. A.; Wanhainen, J. S.

    A large very precise near-field planar scanner was proposed for NASA Lewis Research Center. This scanner would permit near-field measurements over a horizontal scan plane measuring 18.3 m by 18.3 m. Large aperture antennas mounted with antenna boresight vertical could be tested up to 60 GHz. When such a large near field scanner is used for pattern testing, the antenna or antenna system under test does not have to be moved. Hence, such antennas and antenna systems can be positioned and supported to simulate configuration in zero g. Thus, very large and heavy machinery that would be needed to accurately move the antennas are avoided. A preliminary investigation was undertaken to address the mechanical design of such a challenging near-field antenna scanner. The configuration, structural design and results of a parametric NASTRAN structural optimization analysis are contained. Further, the resulting design was dynamically analyzed in order to provide resonant frequency information to the scanner mechanical drive system designers. If other large near field scanners of comparable dimensions are to be constructed, the information can be used for design optimization of these also.

  12. Antenna design for microwave hepatic ablation using an axisymmetric electromagnetic model.

    PubMed

    Bertram, John M; Yang, Deshan; Converse, Mark C; Webster, John G; Mahvi, David M

    2006-02-27

    An axisymmetric finite element method (FEM) model was employed to demonstrate important techniques used in the design of antennas for hepatic microwave ablation (MWA). To effectively treat deep-seated hepatic tumors, these antennas should produce a highly localized specific absorption rate (SAR) pattern and be efficient radiators at approved generator frequencies. As an example, a double slot choked antenna for hepatic MWA was designed and implemented using FEMLABtrade mark 3.0. This paper emphasizes the importance of factors that can affect simulation accuracy, which include boundary conditions, the dielectric properties of liver tissue, and mesh resolution.

  13. Design optimization studies for large-scale contoured beam deployable satellite antennas

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroaki

    2006-05-01

    Satellite communications systems over the past two decades have become more sophisticated and evolved new applications that require much higher flux densities. These new requirements to provide high data rate services to very small user terminals have in turn led to the need for large aperture space antenna systems with higher gain. Conventional parabolic reflectors constructed of metal have become, over time, too massive to support these new missions in a cost effective manner and also have posed problems of fitting within the constrained volume of launch vehicles. Designers of new space antenna systems have thus begun to explore new design options. These design options for advanced space communications networks include such alternatives as inflatable antennas using polyimide materials, antennas constructed of piezo-electric materials, phased array antenna systems (especially in the EHF bands) and deployable antenna systems constructed of wire mesh or cabling systems. This article updates studies being conducted in Japan of such deployable space antenna systems [H. Tanaka, M.C. Natori, Shape control of space antennas consisting of cable networks, Acta Astronautica 55 (2004) 519-527]. In particular, this study shows how the design of such large-scale deployable antenna systems can be optimized based on various factors including the frequency bands to be employed with such innovative reflector design. In particular, this study investigates how contoured beam space antennas can be effective by constructed out of so-called cable networks or mesh-like reflectors. This design can be accomplished via "plane wave synthesis" and by the "force density method" and then to iterate the design to achieve the optimum solution. We have concluded that the best design is achieved by plane wave synthesis. Further, we demonstrate that the nodes on the reflector are best determined by a pseudo-inverse calculation of the matrix that can be interpolated so as to achieve the minimum

  14. Antenna design for microwave hepatic ablation using an axisymmetric electromagnetic model

    PubMed Central

    Bertram, John M; Yang, Deshan; Converse, Mark C; Webster, John G; Mahvi, David M

    2006-01-01

    Background An axisymmetric finite element method (FEM) model was employed to demonstrate important techniques used in the design of antennas for hepatic microwave ablation (MWA). To effectively treat deep-seated hepatic tumors, these antennas should produce a highly localized specific absorption rate (SAR) pattern and be efficient radiators at approved generator frequencies. Methods and results As an example, a double slot choked antenna for hepatic MWA was designed and implemented using FEMLAB™ 3.0. Discussion This paper emphasizes the importance of factors that can affect simulation accuracy, which include boundary conditions, the dielectric properties of liver tissue, and mesh resolution. PMID:16504153

  15. Design of the reduced LQG compensator for the DSS-13 antenna

    NASA Technical Reports Server (NTRS)

    Gawronski, W.

    1993-01-01

    A linear-quadratic-Gaussian (LQG) compensator design procedure is proposed for the DSS-13 antenna. The procedure is based on two properties. It is shown that tracking and flexible motion of the antenna are almost independent (the separation property). As a consequence, compensators for the flexible and tracking parts can be designed separately. It is shown also that the balanced LQG compensator's effort is evenly divided between the controller and the estimator. This allows a minimization of the compensator order, which is important for implementation purposes. An efficient compensator reduction procedure that gives a stable low-order compensator of satisfactory performance is introduced. This approach is illustrated with a detailed compensator design for the DSS-13 antenna. The implementation of this compensator design requires an update of the antenna model.

  16. Preliminary design of a 15 m diameter mechanically scanned deployable offset antenna

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The preliminary design of a 15 meter diameter mechanically scanned, offset rotating, fed parabolic reflector antenna system is reported and the results of preliminary performance, structural and thermal analyses are presented.

  17. Design and performance analysis of the DSS-13 beam waveguide antenna

    NASA Technical Reports Server (NTRS)

    Veruttipong, T.; Imbriale, W.; Bathker, D.

    1990-01-01

    A new 34 m research and development antenna is currently being constructed prior to introducing beam waveguide (BWG) antennas and Ka-band (32 GHz) frequencies into the NASA/JPL Deep Space Network. The new 34 m antenna, fed with either a center or bypass BWG, will lose less than 0.2 dB (excluding surface root mean square and mirror misalignment losses), as compared with a standard-fed Cassegrain antenna a X- (8.4 GHz) and Ka-bands. The antenna is currently under construction and is scheduled to be completed July 1990. Phase 1 of the project is for independent X- and Ka-band receive-only tests. Phase 2 of the project is for simultaneous S- (2.3 GHz) and X-band or X- and Ka-band operation, and the design is currently under way.

  18. New analytical input impedance calculation for fast design of printed narrow slot antenna

    NASA Astrophysics Data System (ADS)

    Akan, Volkan; Yazgan, Erdem

    2011-09-01

    In this article, fast and simple closed-form relations are presented to calculate input impedance of filamentary-excited printed narrow slot antenna on electrically thin dielectric substrate near to half wavelength resonance frequency. This antenna is a complementary structure of thin printed dipole antenna. The obtained formulations have been verified numerically by a commercially available full-wave electromagnetic simulator and then a prototype antenna has been produced. Experimental measurements are realised on the antenna and these measurement values of input impedance also have verified analytical relations and numerical simulations. It is shown that analytical, numerical and experimental results are close to each other. Therefore, these relations can be utilised as an initial design step just before making detailed numerical analyses. Besides, the given relations can be easily realised in CAD-oriented platforms for fast calculations.

  19. Dual-slot antennas for microwave tissue heating: parametric design analysis and experimental validation.

    PubMed

    Brace, Christopher L

    2011-07-01

    Design and validate an efficient dual-slot coaxial microwave ablation antenna that produces an approximately spherical heating pattern to match the shape of most abdominal and pulmonary tumor targets. A dual-slot antenna geometry was utilized for this study. Permutations of the antenna geometry using proximal and distal slot widths from 1 to 10 mm separated by 1-20 mm were analyzed using finite-element electromagnetic simulations. From this series, the most optimal antenna geometry was selected using a two-term sigmoidal objective function to minimize antenna reflection coefficient and maximize the diameter-to-length aspect ratio of heat generation. Sensitivities to variations in tissue properties and insertion depth were also evaluated in numerical models. The most optimal dual-slot geometry of the parametric analysis was then fabricated from semirigid coaxial cable. Antenna reflection coefficients at various insertion depths were recorded in ex vivo bovine livers and compared to numerical results. Ablation zones were then created by applying 50 W for 2-10 min in simulations and ex vivo livers. Mean zone diameter, length, aspect ratio, and reflection coefficients before and after heating were then compared to a conventional monopole antenna using ANOVA with post-hoc t-tests. Statistical significance was indicated for P <0.05. Antenna performance was highly sensitive to dual-slot geometry. The best-performing designs utilized a proximal slot width of 1 mm, distal slot width of 4 mm +/- 1 mm and separation of 8 mm +/- 1 mm. These designs were characterized by an active choking mechanism that focused heating to the distal tip of the antenna. A dual-band resonance was observed in the most optimal design, with a minimum reflection coefficient of -20.9 dB at 2.45 and 1.25 GHz. Total operating bandwidth was greater than 1 GHz, but the desired heating pattern was achieved only near 2.45 GHz. As a result, antenna performance was robust to changes in insertion depth and

  20. Design and testing of an active polyvinylidene fluoride aperture antenna

    NASA Astrophysics Data System (ADS)

    Washington, Gregory N.

    1997-06-01

    Recent studies have shown that reflector surface adaptation can achieve performance characteristics on the order of some phase array antennas without the complexity and cost. The work presented in this study develops the experimental groundwork for a class of antennas capable of variable directivity (beam steering) and power density (beam shaping) The actuation for these antennas is employed by bonding polyvinylidene fluoride (PVDF) film to a metalized mylar substrate. A voltage drop across the material will cause the material to expand or contract. This movement causes a moment to be developed in the structure which causes structural bending. Several studies of flexible structures with PVDF films have shown that cylindrical antennas can achieve significant deflections and thereby offer beneficial changes to radiation patterns emanating from aperture antennas. In this study, relatively large curved actuators are modeled and a deflection vs. force relationship is developed. This relationship is then simulated and compared to experimental results. A final simulation of the far field radiation patterns from a given set of deflections is then presented.

  1. A Novel Design of Circular Edge Bow-Tie Nano Antenna for Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Haque, Ahasanul; Reza, Ahmed Wasif; Kumar, Narendra

    2015-11-01

    In this study, a novel nano antenna is designed in order to convert the high frequency solar energy, thermal energy or earth re-emitted sun's energy into electricity. The proposed antenna is gold printed on a SiO2 layer, designed as a circular edge bow-tie with a ground plane at the bottom of the substrate. The Lorentz-Drude model is used to analyze the behavior of gold at the infrared band of frequencies. The proposed antenna is designed by 3D-electromagnetic solver, and analyzed for optimization of metal thickness, gap size, and antenna's geometrical length. Simulations are conducted in order to investigate the behavior of the antenna illuminated by the circularly polarized plane wave. The numerical simulations are studied for improving the harvesting E-field of the antenna within 5 THz-40 THz frequency range. The proposed antenna offers multiple resonance frequency and better return loss within the frequency bands of 23.2 THz to 27 THz (bandwidth 3.8 THz) and 31 THz to 35.9 THz (bandwidth 4.9 THz). An output electric field of 0.656 V/µm is simulated at 25.3 THz. The best fitted gap size at the feed point is achieved as 50 nm with the substrate thickness of 1.2 µm.

  2. Ultra-wideband miniaturized microstrip patch antennas for wireless communications: Design guidelines and modeling

    NASA Astrophysics Data System (ADS)

    Dandu, Varun Kumar

    The number of wireless communication applications continue to increase steadily, leading to competition for currently allocated frequency bands. Capacity issues in form of data rate and latency have always been a bottleneck for broadband wireless-communication usage. New communication systems like ultra-wideband (UWB) require larger bandwidth than what is normally utilized with traditional antenna techniques. The interest for compact consumer electronics is growing in the meantime, creating a demand on efficient and low profile antennas which can be integrated on a printed circuit board. The main objective of this thesis is to study, design, analyze and implement UWB low profile microstrip patch antenna that satisfy UWB technology requirements. Some methods to extend the bandwidth and other antenna parameters associated with wideband usages are studied. Several techniques are used for optimal UWB bandwidth performance of the UWB microstrip patch antenna. The performance parameters such as VSWR, Gain and radiation pattern of the UWB microstrip patch antenna is extensively investigated with simulations using FEKO. A set of simple design guidelines is proposed to provide approximate rules that result in optimum "first-pass" designs of probe-fed, miniaturized, low profile, microstrip UWB antennas using different bandwidth-enhancement techniques to satisfy UWB bandwidth that require minimal tuning.

  3. Analysis and verification of a proposed antenna design for an implantable RFID Tag at 915 MHz

    NASA Astrophysics Data System (ADS)

    Bakore, Rahul

    This work focused on design and analysis of an antenna to be used with an RFID tag that is implanted in human brain tissue. The goal is to maximize the power transferred between the external RFID measurement system and the implanted RFID tag while minimizing the power dissipated within the surrounding tissue. The commercial computational electromagnetics software package COMSOL, based on finite element method (FEM) has been used for design process. The COMSOL models have been validated against additional simulations using the FEKO commercial package based on method of moments (MOM) as well as against measurement of test antenna structures radiating in bulk homogeneous medium. The proposed antenna geometry is compatible with the human tissue and viable for use in implantable RFID Tag. The proposed antenna is a planar folded dipole made from a gold conductor that acts as a biocompatible material. The metal thickness is 1 micrometer and the overall antenna dimensions are 22 mm × 3.5 mm. The antenna structure also includes a dielectric substrate and an acrylic coating. The antenna impedance is 28 + j201.5 Ω at 915 MHz. The inductive reactance is high enough to compensate the capacitive reactance of RFID tag and the antenna resistance is close to effective chip resistance providing a conjugate match. This antenna fulfills the criteria for minimizing the power dissipation within the human tissue. Also, a radiation efficiency of 87% is achieved with this antenna at 915 MHz. The quality factor of greater than 10 is achieved which is sufficient to turn on the diodes in the electronic circuit of the RFID tag due to the high D.C voltage obtained.

  4. Infrapatellar Straps Decrease Patellar Tendon Strain at the Site of the Jumper’s Knee Lesion

    PubMed Central

    Lavagnino, Michael; Arnoczky, Steven P.; Dodds, Julie; Elvin, Niell

    2011-01-01

    Background: The impetus for the use of patellar straps in the treatment of patellar tendinopathy has largely been based on empirical evidence and not on any mechanistic rationale. A computational model suggests that patellar tendinopathy may be a result of high localized tendon strains that occur at smaller patella–patellar tendon angles (PPTAs). Hypothesis: Infrapatellar straps will decrease the mean localized computational strain in the area of the patellar tendon commonly involved in jumper’s knee by increasing the PPTA. Study Design: Controlled laboratory study. Methods: Twenty adult males had lateral weightbearing and nonweightbearing radiographs of their knees taken with and without 1 of 2 infrapatellar straps at 60° of knee flexion. Morphologic measurements of PPTA and patellar tendon length with and without the straps were used as input data into a previously described computational model to calculate average and maximum strain at the common location of the jumper’s knee lesion during a simulated jump landing. Results: The infrapatellar bands decreased the predicted localized strain (average and maximum) in the majority of participants by increasing PPTA and/or decreasing patellar tendon length. When both PPTA and patellar tendon length were altered by the straps, there was a strong and significant correlation with the change in predicted average localized strain with both straps. Conclusion: Infrapatellar straps may limit excessive patella tendon strain at the site of the jumper’s knee lesion by increasing PPTA and decreasing patellar tendon length rather than by correcting some inherent anatomic or functional abnormality in the extensor apparatus. Clinical Relevance: The use of infrapatellar straps may help prevent excessive localized tendon strains at the site of the jumper’s knee lesion during a jump landing. PMID:23016021

  5. A Novel Design of Frequency Reconfigurable Antenna for UWB Application

    NASA Astrophysics Data System (ADS)

    Yang, Xiaolin; Yu, Ziliang; Wu, Zheng; Shen, Huajiao

    2016-09-01

    In this paper, we present a novel frequency reconfigurable antenna which could be easily operate in a single notched-band (WiMAX (3.3-3.6 GHz)) UWB frequency band, another single notched-band (WLAN (5-6 GHz)) UWB frequency band and the dual band-notched UWB frequency band (the stopband covers the WiMAX (3.3-3.6 GHz) and WLAN (5-6 GHz)). The reconfigurability is achieved by changing the states of PIN diodes. The simulated results are in agreement well with the measured results. And the measured patterns are slightly changed with antenna reconfiguration. The proposed antenna is a good candidate for various UWB applications.

  6. Manufacturing error sensitivity analysis and optimal design method of cable-network antenna structures

    NASA Astrophysics Data System (ADS)

    Zong, Yali; Hu, Naigang; Duan, Baoyan; Yang, Guigeng; Cao, Hongjun; Xu, Wanye

    2016-03-01

    Inevitable manufacturing errors and inconsistency between assumed and actual boundary conditions can affect the shape precision and cable tensions of a cable-network antenna, and even result in failure of the structure in service. In this paper, an analytical sensitivity analysis method of the shape precision and cable tensions with respect to the parameters carrying uncertainty was studied. Based on the sensitivity analysis, an optimal design procedure was proposed to alleviate the effects of the parameters that carry uncertainty. The validity of the calculated sensitivities is examined by those computed by a finite difference method. Comparison with a traditional design method shows that the presented design procedure can remarkably reduce the influence of the uncertainties on the antenna performance. Moreover, the results suggest that especially slender front net cables, thick tension ties, relatively slender boundary cables and high tension level can improve the ability of cable-network antenna structures to resist the effects of the uncertainties on the antenna performance.

  7. Design and analysis of ultra-wideband antennas for transient field excitations

    NASA Astrophysics Data System (ADS)

    Kotzev, Miroslav; Kreitlow, Matthias; Gronwald, Frank

    2016-09-01

    This work addresses the design of two ultra-wideband antennas for the application of transient field measurements that are characterized by frequency spectra that typically range from a few MHz to several GHz. The motivation for their design is the excitation of high power transient pulses, such as double exponential or damped sinusoidal pulses, within highly resonant metallic enclosures. The antenna design is based on two independent numerical full-wave solvers and it is aimed to achieve a low return loss over a wide range of frequencies together with a high pulse fidelity. It turns out that antennas of the conical and discone type do achieve satisfactory broadband characteristics while limitations towards low frequencies persist. Also the concept of fidelity factor turns out as advantageous to determine whether the proposed antennas allow transmitting certain broadband pulse forms.

  8. Design of a dual slot antenna for small animal microwave ablation studies.

    PubMed

    Moon, Tyler J; Brace, Christopher L; Moon, Tyler J; Brace, Christopher L; Brace, Christopher L; Moon, Tyler J

    2016-08-01

    This study presents the development of a dual-slot antenna for small animal tumor ablation. By using a dual-slot design at 8 GHz, it was hypothesized that smaller and more spherical ablations can be produced. After computer-aided design optimization, antennas were fabricated and ablations performed at 5-20 W for 15-120 s with the objective of creating ablations with a diameter/length aspect ratio of at least 0.9. The new dual-slot design at 8 GHz created significantly more spherical ablations than a commercial antenna at 2.45 GHz in ex vivo liver tissue (Average Aspect Ratio 0.8081 vs. 0.4532, p <;<; 0.05). In vivo studies confirmed the highly spherical results ex vivo. Initial testing shows that the dual-slot antenna and 8 GHz generator can be used to ablate tumors in mice.

  9. Antennas Designed for Advanced Communications for Air Traffic Management (AC/ATM) Project

    NASA Technical Reports Server (NTRS)

    Zakrajsek, Robert J.

    2000-01-01

    The goal of the Advanced Communications for Air Traffic Management (AC/ATM) Project at the NASA Glenn Research Center at Lewis Field is to enable a communications infrastructure that provides the capacity, efficiency, and flexibility necessary to realize a mature free-flight environment. The technical thrust of the AC/ATM Project is targeted at the design, development, integration, test, and demonstration of enabling technologies for global broadband aeronautical communications. Since Ku-band facilities and equipment are readily available, one of the near-term demonstrations involves a link through a Kuband communications satellite. Two conformally mounted antennas will support the initial AC/ATM communications links. Both of these are steered electronically through monolithic microwave integrated circuit (MMIC) amplifiers and phase shifters. This link will be asymmetrical with the downlink to the aircraft (mobile vehicle) at a throughput rate of greater than 1.5 megabits per second (Mbps), whereas the throughput rate of the uplink from the aircraft will be greater than 100 kilobits per second (kbps). The data on the downlink can be narrow-band, wide-band, or a combination of both, depending on the requirements of the experiment. The AC/ATM project is purchasing a phased-array Ku-band transmitting antenna for the uplink from the test vehicle. Many Ku-band receiving antennas have been built, and one will be borrowed for a short time to perform the initial experiments at the NASA Glenn Research Center at Lewis Field. The Ku-band transmitting antenna is a 254-element MMIC phased-array antenna being built by Boeing Phantom Works. Each element can radiate 100 mW. The antenna is approximately 43-cm high by 24-cm wide by 3.3-cm thick. It can be steered beyond 60 from broadside. The beamwidth varies from 6 at broadside to 12 degrees at 60 degrees, which is typical of phased-array antennas. When the antenna is steered to 60 degrees, the beamwidth will illuminate

  10. THE COUPLING AND MUTUAL IMPEDANCE BETWEEN BALANCED WIRE-ARM CONICAL LOG-SPIRAL ANTENNAS

    DTIC Science & Technology

    CONICAL ANTENNAS, *COUPLED ANTENNAS, * HELICAL ANTENNAS, ANTENNA COMPONENTS, ANTENNA RADIATION PATTERNS, COUPLINGS, DESIGN, ELECTRIC CURRENTS...ELECTRIC POTENTIAL, ELECTRICAL IMPEDANCE, MEASUREMENT, POLARIZATION, PROPAGATION, ROTATION, SPIRAL ANTENNAS, THEORY

  11. Long range ultra-high frequency (UHF) radio frequency identification (RFID) antenna design

    NASA Astrophysics Data System (ADS)

    Reynolds, Nathan D.

    There is an ever-increasing demand for radio frequency identification (RFID) tags that are passive, long range, and mountable on multiple surfaces. Currently, RFID technology is utilized in numerous applications such as supply chain management, access control, and public transportation. With the combination of sensory systems in recent years, the applications of RFID technology have been extended beyond tracking and identifying. This extension includes applications such as environmental monitoring and healthcare applications. The available sensory systems usually operate in the medium or high frequency bands and have a low read range. However, the range limitations of these systems are being overcome by the development of RFID sensors focused on utilizing tags in the ultra-high frequency (UHF) band. Generally, RFID tags have to be mounted to the object that is being identified. Often the objects requiring identification are metallic. The inherent properties of metallic objects have substantial effects on nearby electromagnetic radiation; therefore, the operation of the tag antenna is affected when mounted on a metallic surface. This outlines one of the most challenging problems for RFID systems today: the optimization of tag antenna performance in a complex environment. In this research, a novel UHF RFID tag antenna, which has a low profile, long range, and is mountable on metallic surfaces, is designed analytically and simulated using a 3-D electromagnetic simulator, ANSYS HFSS. A microstrip patch antenna is selected as the antenna structure, as patch antennas are low profile and suitable for mounting on metallic surfaces. Matching and theoretical models of the microstrip patch antenna are investigated. Once matching and theory of a microstrip patch antenna is thoroughly understood, a unique design technique using electromagnetic band gap (EBG) structures is explored. This research shows that the utilization of an EBG structure in the patch antenna design yields

  12. Concepted design of a surface measurement system for large deployable space antennas

    NASA Technical Reports Server (NTRS)

    Neiswander, R. S.

    1982-01-01

    The sensor system is in essence a point design, specifically interfacing with the Harris, Inc., 1000 meter deployable mesh communication antenna. The design can, without large modification, be adapted to other large deployable antennas such as the Lockheed Wrap-rib, the General Dynamics Precision Erectable Truss and the TRW Advanced Sunflower antennas. Measurements are optical displacements. The elements of the system are a central cluster of receivers near the apex of the antenna and active bright targets at the antenna. The cluster defines a single coordinate frame from which all surface positions are referenced. The receivers continuously observe an extended array of sample points located throughout the reflecting surface and its supporting structure. For the Harris antenna, the surface samples are at the mesh gore lines and at the supporting hoop. Output data is in real-time, compatible with on-board processing and active control of antenna figure. Lifetime of the system is at least 10 years continuous operation in space.

  13. Concepted design of a surface measurement system for large deployable space antennas

    NASA Astrophysics Data System (ADS)

    Neiswander, R. S.

    1982-03-01

    The sensor system is in essence a point design, specifically interfacing with the Harris, Inc., 1000 meter deployable mesh communication antenna. The design can, without large modification, be adapted to other large deployable antennas such as the Lockheed Wrap-rib, the General Dynamics Precision Erectable Truss and the TRW Advanced Sunflower antennas. Measurements are optical displacements. The elements of the system are a central cluster of receivers near the apex of the antenna and active bright targets at the antenna. The cluster defines a single coordinate frame from which all surface positions are referenced. The receivers continuously observe an extended array of sample points located throughout the reflecting surface and its supporting structure. For the Harris antenna, the surface samples are at the mesh gore lines and at the supporting hoop. Output data is in real-time, compatible with on-board processing and active control of antenna figure. Lifetime of the system is at least 10 years continuous operation in space.

  14. Concepted design of a surface measurement system for large deployable space antennas

    NASA Technical Reports Server (NTRS)

    Neiswander, R. S.

    1982-01-01

    The sensor system is in essence a point design, specifically interfacing with the Harris, Inc., 1000 meter deployable mesh communication antenna. The design can, without large modification, be adapted to other large deployable antennas such as the Lockheed Wrap-rib, the General Dynamics Precision Erectable Truss and the TRW Advanced Sunflower antennas. Measurements are optical displacements. The elements of the system are a central cluster of receivers near the apex of the antenna and active bright targets at the antenna. The cluster defines a single coordinate frame from which all surface positions are referenced. The receivers continuously observe an extended array of sample points located throughout the reflecting surface and its supporting structure. For the Harris antenna, the surface samples are at the mesh gore lines and at the supporting hoop. Output data is in real-time, compatible with on-board processing and active control of antenna figure. Lifetime of the system is at least 10 years continuous operation in space.

  15. User Antennas

    NASA Technical Reports Server (NTRS)

    Jamnejad, Vahraz; Cramer, Paul

    1990-01-01

    The following subject areas are covered: (1) impact of frequency change of user and spacecraft antenna gain and size; (2) basic personal terminal antennas (impact of 20/30 GHz frequency separation; parametric studies - gain, size, weight; gain and figure of merit (G/T); design data for selected antenna concepts; critical technologies and development goals; and recommendations); and (3) user antenna radiation safety concerns.

  16. A review of performance characteristics of satellite antennas and some observations on future directions in satellite antenna design

    NASA Technical Reports Server (NTRS)

    Mittra, R.; Galindo-Israel, V.; Bathker, D. A.; Moule, W. N.

    1977-01-01

    A general review of the state-of-the-art and new directions in research and development of spacecraft antennas is presented. Three general classes of antennas are discussed: phased arrays, lenses (dielectric and waveguide), and reflector antennas. Presently, the antenna with most applications is the reflector with considerable research being performed to improve its scan and multiple beam characteristics. Future applications for spacecraft antennas and research goals to meet these projected needs also are discussed.

  17. Design optical antenna and fiber coupling system based on the vector theory of reflection and refraction.

    PubMed

    Jiang, Ping; Yang, Huajun; Mao, Shengqian

    2015-10-05

    A Cassegrain antenna system and an optical fiber coupling system which consists of a plano-concave lens and a plano-convex lens are designed based on the vector theory of reflection and refraction, so as to improve the transmission performance of the optical antenna and fiber coupling system. Three-dimensional ray tracing simulation are performed and results of the optical aberrations calculation and the experimental test show that the aberrations caused by on-axial defocusing, off-axial defocusing and deflection of receiving antenna can be well corrected by the optical fiber coupling system.

  18. Design of WLAN microstrip antenna for 5.17 - 5.835 GHz

    NASA Astrophysics Data System (ADS)

    Bugaj, Jarosław; Bugaj, Marek; Wnuk, Marian

    2017-04-01

    This paper presents the project of miniaturized WLAN Antenna made in microstrip technique working at a frequency of 5.17 - 5.835 GHz in 802.11ac IEEE standard. This dual layer antenna is designed on RT/duroid 5870 ROGERS CORPORATION substrate with dielectric constant 2.33 and thickness of 3.175 mm. The antenna parameters such as return loss, VSWR, gain and directivity are simulated and optimized using commercial computer simulation technology microwave studio (CST MWS). The paper presents the results of discussed numerical analysis.

  19. Conformal Antenna and Array Design Using Novel Electronic Materials

    DTIC Science & Technology

    2010-03-31

    4. Miniature conformal spirals on textured/ metamaterial ferrite substrates (middle) to replace traditional blade antennas that protrude nearly...waves (as photonic crystal modes) in textured or layered dielectric media ( metamaterials ). Of importance is that these modes are non- reflecting at...low loss ferrites within the substrate of the printed coupled lines will significantly enhance bandwidth and radiation. A concept that includes

  20. Present Status of the ITER-like ICRF Antenna on JET

    SciTech Connect

    Durodie, F.; Huygen, S.; Lerche, E.; Ongena, J.; Van Eester, D.; Vrancken, M.; Gauthier, M.; Goulding, R.

    2009-11-26

    The commissioning of the ITER-Like ICRF Antenna (ILA) on JET plasmas from May 2008 to April 2009 in various conditions (33, 42 and 47 MHz, L- and H-mode, antenna strap-plasma separatrix distances of {approx}9 to 17 cm) has provided relevant information for future antenna design and operation. The maximum power density achieved was 6.2 MW/m{sup 2} in L-mode with strap to plasma separatrix distance of {approx}9-10 cm at 42 MHz on the lower half of the ILA extrapolating to 8 MW/m{sup 2} if the full generator power had been available. Efficient (trip-free operation) ELM tolerance was obtained both at 33 and 42 MHz on a large range of ELMs with strap voltages up to 42 kV and a maximum power density of 4.1 MW/m{sup 2}. The paper reviews these achievements as well as remaining issues.

  1. MoM-based topology optimization method for planar metallic antenna design

    NASA Astrophysics Data System (ADS)

    Liu, Shutian; Wang, Qi; Gao, Renjing

    2016-12-01

    The metallic antenna design problem can be treated as a problem to find the optimal distribution of conductive material in a certain domain. Although this problem is well suited for topology optimization method, the volumetric distribution of conductive material based on 3D finite element method (FEM) has been known to cause numerical bottlenecks such as the skin depth issue, meshed "air regions" and other numerical problems. In this paper a topology optimization method based on the method of moments (MoM) for configuration design of planar metallic antenna was proposed. The candidate structure of the planar metallic antenna was approximately considered as a resistance sheet with position-dependent impedance. In this way, the electromagnetic property of the antenna can be analyzed easily by using the MoM to solve the radiation problem of the resistance sheet in a finite domain. The topology of the antenna was depicted with the distribution of the impedance related to the design parameters or relative densities. The conductive material (metal) was assumed to have zero impedance, whereas the non-conductive material was simulated as a material with a finite but large enough impedance. The interpolation function of the impedance between conductive material and non-conductive material was taken as a tangential function. The design of planar metallic antenna was optimized for maximizing the efficiency at the target frequency. The results illustrated the effectiveness of the method.

  2. Designing Ground Antennas for Maximum G/T: Cassegrain or Gregorian?

    NASA Technical Reports Server (NTRS)

    Imbriale, William A.

    2005-01-01

    For optimum performance, a ground antenna system must maximize the ratio of received signal to the receiving system noise power, defined as the ratio of antenna gain to system-noise temperature (G/T). The total system noise temperature is the linear combination of the receiver noise temperature (including the feed system losses) and the antenna noise contribution. Hence, for very low noise cryogenic receiver systems, antenna noise-temperature properties are very significant contributors to G/T.It is well known that, for dual reflector systems designed for maximum gain, the gain performance of the antenna system is the same for both Cassegrain and Gregorian configurations. For a12-meter antenna designed to be part of the large array based Deep Space Network, a Cassegrain configuration designed for maximum G/T at X-band was 0.7 dB higher than the equivalent Gregorian configuration. This study demonstrates that, for maximum GIT, the dual shaped Cassegrain design is always better than the Gregorian.

  3. Design analysis of an implant and antenna system by using Taguchi method

    NASA Astrophysics Data System (ADS)

    Celik, Nevin; Turgut, Emre; Bayazit, Yilmaz

    2017-08-01

    In present study, to investigate the thermal effects of the rechargeable neuromodulation implants (an implant and antenna together) in the body, a numerical analysis is performed by using commercial software ANSYS. Since it is well established that both the antenna and the implant generate heat, both of these heat sources may increase the tissue temperature in the subcutaneous zone and may also increase the temperature in the deeper tissue. Therefore, the sizes and heat generation amounts of the implant-antenna system gain great importance and a parametric evaluation that shows the effects of the design parameters on the temperature becomes necessary. For this aim, an optimization study is performed. The runs of the numerical simulations are determined by well-known design analysis method, namely Taguchi and the parametric evaluation of the study is carried out by Analysis of Variance (ANOVA) method. The design parameters considered are; (i) heat generated by the antenna q a (50, 52 and 54 W/m2), (ii) heat generated by the implant q i (30 and 35 W/m2), (iii) thickness of the implant t i (9, 11, and 13 mm) and finally (iv) the radius of the antenna R a (31, 35, 39 mm). The results showed that higher antenna radii result in higher temperatures in the tissue, whilst the least effective design parameter on the temperature is the heat generation of the implant.

  4. Computer simulations for rf design of a Spallation Neutron Source external antenna H ion source

    SciTech Connect

    Lee, Sung-Woo; Goulding, Richard Howell; Kang, Yoon W; Shin, Ki; Welton, Robert F

    2010-01-01

    Electromagnetic modeling of the multicusp external antenna H ion source for the Spallation Neutron Source SNS has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as . Insulation designs along with material selections such as ferrite and Teflon could be included in the computer simulations to compare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion.

  5. Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna

    SciTech Connect

    Pace, D. C.; Van Zeeland, M. A.; Fishler, B.; Murphy, C.

    2016-08-02

    Neutral beam prompt losses (injected neutrals that ionize such that their first poloidal transit intersects with the wall) can put appreciable power on the outer wall of tokamaks, and this power may damage the wall or other internal components. These prompt losses are simulated including a protruding helicon antenna installation in the DIII-D tokamak and it is determined that 160 kW of power will impact the antenna during the injection of a particular neutral beam. Protective graphite tiles are designed in response to this modeling and the wall shape of the installed antenna is precisely measured to improve the accuracy of these calculations. Initial experiments con rm that the antenna component temperature increases according to the amount of neutral beam energy injected into the plasma. Incorporating neutral beam prompt loss considerations into the design of this in-vessel component serves to ensure that adequate protection or cooling is provided.

  6. Computer simulations for rf design of a Spallation Neutron Source external antenna H- ion source.

    PubMed

    Lee, S W; Goulding, R H; Kang, Y W; Shin, K; Welton, R F

    2010-02-01

    Electromagnetic modeling of the multicusp external antenna H(-) ion source for the Spallation Neutron Source (SNS) has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as sigma. Insulation designs along with material selections such as ferrite and Teflon could be included in the computer simulations to compare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion.

  7. Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna

    DOE PAGES

    Pace, D. C.; Van Zeeland, M. A.; Fishler, B.; ...

    2016-08-02

    Neutral beam prompt losses (injected neutrals that ionize such that their first poloidal transit intersects with the wall) can put appreciable power on the outer wall of tokamaks, and this power may damage the wall or other internal components. These prompt losses are simulated including a protruding helicon antenna installation in the DIII-D tokamak and it is determined that 160 kW of power will impact the antenna during the injection of a particular neutral beam. Protective graphite tiles are designed in response to this modeling and the wall shape of the installed antenna is precisely measured to improve the accuracymore » of these calculations. Initial experiments con rm that the antenna component temperature increases according to the amount of neutral beam energy injected into the plasma. Incorporating neutral beam prompt loss considerations into the design of this in-vessel component serves to ensure that adequate protection or cooling is provided.« less

  8. LQG controller design using GUI: application to antennas and radio-telescopes

    PubMed

    Maneri; Gawronski

    2000-01-01

    The Linear Quadratic Gaussian (LQG) algorithm has been used to control the JPL's beam wave-guide, and 70-m antennas. This algorithm significantly improves tracking precision in a wind disturbed environment. Based on this algorithm and the implementation experience a Matlab based Graphical User Interface (GUI) was developed to design the LQG controllers applicable to antennas and radiotelescopes. The GUI is described in this paper. It consists of two parts the basic LQG design and the fine-tuning of the basic design using a constrained optimization algorithm. The presented GUI was developed to simplify the design process, to make the design process user-friendly, and to enable design of an LQG controller for one with a limited control engineering background. The user is asked to manipulate the GUI sliders and radio buttons to watch the antenna performance. Simple rules are given at the GUI display.

  9. Studies in Fin-Line Antenna Design for Phased Array Applications.

    DTIC Science & Technology

    1983-11-01

    bend fin-line ........ 2 2. Extended dielectric fin-lime antenna . . . ............ 4 3. Dielectric rod fin-linm antena ..................... S 4...endftire. Mhe latter Is perhaps the most difficult criterion to satisfy. It is easy to visualize a broadside fin-line antena based on a * * periodic...of endfire fin-line antenas , whose designs are shown in fils. 2-5.* In Fig. 2, an antenna is shown in which the dielectric portion of the fin-line wee

  10. DESIGN AND PERFORMANCE OF A LOW-FREQUENCY CROSS-POLARIZED LOG-PERIODIC DIPOLE ANTENNA

    SciTech Connect

    Raja, K. Sasikumar; Kathiravan, C.; Ramesh, R.; Rajalingam, M.; Barve, Indrajit V.

    2013-07-01

    We report the design and performance of a cross-polarized log-periodic dipole (CLPD) antenna for observations of polarized radio emission from the solar corona at low frequencies. The measured isolation between the two mutually orthogonal log-periodic dipole antennas was as low as Almost-Equal-To - 43 dBm in the 65-95 MHz range. We carried out observations of the solar corona at 80 MHz with the above CLPD and successfully recorded circularly polarized emission.

  11. Design of Compact Penta-Band and Hexa-Band Microstrip Antennas

    NASA Astrophysics Data System (ADS)

    Srivastava, Kunal; Kumar, Ashwani; Kanaujia, Binod K.

    2016-03-01

    This paper presents the design of two multi-band microstrip antennas. The antenna-1 gives Penta-Band and antenna-2 gives Hexa-band in the WLAN band. The frequency bands of the antenna-1 are Bluetooth 2.47 GHz (2.43 GHz-2.54 GHz), WiMax band 3.73 GHz (3.71 GHz-3.77 GHz), WLAN 5.1 GHz (4.99 GHz-5.13 GHz), upper WLAN 6.36 GHz (6.29 GHz-6.43 GHz), C band band 7.42 GHz (7.32 GHz-7.50 GHz) and the antenna-2 are WLAN band 2.6 GHz (2.56 GHz-2.63 GHz), 3.0 GHz (2.94 GHz-3.05 GHz), WiMax band 3.4 GHz (3.34 GHz-3.55 GHz), 4.85 GHz (4.81 GHz-4.92 GHz), WLAN 5.3 GHz (5.27 GHz-5.34 GHz) and upper WLAN 6.88 GHz. Both the antennas are fabricated and their measured results are presented to validate the simulated results. Proposed antennas have compact sizes and good radiation performances.

  12. Design of a compact tuning fork-shaped notched ultrawideband antenna for wireless communication application.

    PubMed

    Shakib, M N; Moghavvemi, M; Mahadi, W N L

    2014-01-01

    A new compact planar notched ultrawideband (UWB) antenna is designed for wireless communication application. The proposed antenna has a compact size of 0.182λ × 0.228λ × 0.018λ where λ is the wavelength of the lowest operating frequency. The antenna is comprised of rectangular radiating patch, ground plane, and an arc-shaped strip in between radiating patch and feed line. By introducing a new Tuning Fork-shaped notch in the radiating plane, a stopband is obtained. The antenna is tested and measured. The measured result indicated that fabricated antenna has achieved a wide bandwidth of 4.33-13.8 GHz (at -10 dB return loss) with a rejection frequency band of 5.28-6.97 GHz (WiMAX, WLAN, and C-band). The effects of the parameters of the antenna are discussed. The experiment results demonstrate that the proposed antenna can well meet the requirement for the UWB communication in spite of its compactness and small size.

  13. Design of a Compact Tuning Fork-Shaped Notched Ultrawideband Antenna for Wireless Communication Application

    PubMed Central

    Shakib, M. N.; Moghavvemi, M.; Mahadi, W. N. L.

    2014-01-01

    A new compact planar notched ultrawideband (UWB) antenna is designed for wireless communication application. The proposed antenna has a compact size of 0.182λ × 0.228λ × 0.018λ where λ is the wavelength of the lowest operating frequency. The antenna is comprised of rectangular radiating patch, ground plane, and an arc-shaped strip in between radiating patch and feed line. By introducing a new Tuning Fork-shaped notch in the radiating plane, a stopband is obtained. The antenna is tested and measured. The measured result indicated that fabricated antenna has achieved a wide bandwidth of 4.33–13.8 GHz (at −10 dB return loss) with a rejection frequency band of 5.28–6.97 GHz (WiMAX, WLAN, and C-band). The effects of the parameters of the antenna are discussed. The experiment results demonstrate that the proposed antenna can well meet the requirement for the UWB communication in spite of its compactness and small size. PMID:24723835

  14. Design and Optimization of Passive UHF RFID Tag Antenna for Mounting on or inside Material Layers

    NASA Astrophysics Data System (ADS)

    Shao, Shuai

    There is great desire to employ passive UHF RFID tags for inventory tracking and sensing in a diversity of applications and environments. Owing to its battery-free operation, non-line-of sight detection, low cost, long read range and small form factor, each year billions of RFID tags are being deployed in retail, logistics, manufacturing, biomedical inventories, among many other applications. However, the performance of these RFID systems has not met expectations. This is because a tag's performance deteriorates significantly when mounted on or inside arbitrary materials. The tag antenna is optimized only for a given type of material at a certain location of placement, and detuning takes place when attached to or embedded in materials with dielectric properties outside the design range. Thereby, different customized tags may be needed for identifying objects even within the same class of products. This increases the overall cost of the system. Furthermore, conventional copper foil-based RFID tag antennas are prone to metal fatigue and wear, and cannot survive hostile environments where antennas could be deformed by external forces and failures occur. Therefore, it is essential to understand the interaction between the antenna and the material in the vicinity of the tag, and design general purpose RFID tag antennas possessing excellent electrical performance as well as robust mechanical structure. A particularly challenging application addressed here is designing passive RFID tag antennas for automotive tires. Tires are composed of multiple layers of rubber with different dielectric properties and thicknesses. Furthermore, metallic plies are embedded in the sidewalls and steel belts lie beneath the tread to enforce mechanical integrity. To complicate matters even more, a typical tire experiences a 10% stretching during the construction process. This dissertation focuses on intuitively understanding the interaction between the antenna and the material in the

  15. Design and investigation of planar technology based ultra-wideband antenna with directional radiation patterns

    NASA Astrophysics Data System (ADS)

    Meena, M. L.; Parmar, Girish; Kumar, Mithilesh

    2016-03-01

    A novel design technique based on planar technology for ultra-wideband (UWB) antennas with different ground shape having directional radiation pattern is being presented here. Firstly, the L-shape corner reflector ground plane antenna is designed with microstrip feed line in order to achieve large bandwidth and directivity. Thereafter, for the further improvement in the directivity as well as for better impedance matching the parabolic-shape ground plane has been introduced. The coaxial feed line is given for the proposed directional antenna in order to achieve better impedance matching with 50 ohm transmission line. The simulation analysis of the antenna is done on CST Microwave Studio software using FR-4 substrate having thickness of 1.6 mm and dielectric constant of 4.4. The simulated result shows a good return loss (S11) with respect to -10 dB. The radiation pattern characteristic, angular width, directivity and bandwidth performance of the antenna have also been compared at different resonant frequencies. The designed antennas exhibit low cost, low reflection coefficient and better directivity in the UWB frequency band.

  16. Design and investigation of planar technology based ultra-wideband antenna with directional radiation patterns

    SciTech Connect

    Meena, M. L. Parmar, Girish Kumar, Mithilesh

    2016-03-09

    A novel design technique based on planar technology for ultra-wideband (UWB) antennas with different ground shape having directional radiation pattern is being presented here. Firstly, the L-shape corner reflector ground plane antenna is designed with microstrip feed line in order to achieve large bandwidth and directivity. Thereafter, for the further improvement in the directivity as well as for better impedance matching the parabolic-shape ground plane has been introduced. The coaxial feed line is given for the proposed directional antenna in order to achieve better impedance matching with 50 ohm transmission line. The simulation analysis of the antenna is done on CST Microwave Studio software using FR-4 substrate having thickness of 1.6 mm and dielectric constant of 4.4. The simulated result shows a good return loss (S11) with respect to -10 dB. The radiation pattern characteristic, angular width, directivity and bandwidth performance of the antenna have also been compared at different resonant frequencies. The designed antennas exhibit low cost, low reflection coefficient and better directivity in the UWB frequency band.

  17. Alcator C-Mod ICRF antenna and matching circuit

    SciTech Connect

    Golovato, S.N.; Porkolab, M.; Takase, Y.; Holcomb, H.L. )

    1989-07-01

    Alcator C-mod will be a compact, high field, high density, divertor tokamak. Two FMIT transmitters will supply 4 MW of power in 1 sec pulses at 80 MHz for ICRF heating. Fast wave minority heating experiments are planned in D({sup 3}He) at 8 T and D(H) at 5.5 T. The first antenna will have a single current strap inside a box structure, which will be movable radially. The antenna will be inserted through a side port, making the rf power density on the antenna surface {similar to}2 kW/cm{sup 2} at 2 MW. the antenna will be center-trapped for mechanical strength and have a double layer Faraday screen tilted along the field lines. The antenna geometry was chosen to maximize power coupling assuming voltage-limited operation. A wide antenna with slotted box sides appears the best design, and 10 {Omega} of loading is required to couple 2 MW of power at a voltage limit of 40 kV. Matching is achieved by choice of the drive point to a resonant circuit formed by the antenna and a loop of transmission line outside of the vacuum and by tuning elements in the transmission line to the transmitter.

  18. Alcator C-Mod ICRF antenna and matching circuit

    SciTech Connect

    Golovato, S.N.; Porkolab, M.; Takase, Y.; Holcomb, H.L.

    1989-06-01

    Alcator C-Mod will be a compact, high field, high density, divertor tokamak. Two FMIT transmitters will supply 4 MW of power in 1 sec pulses at 80 MHz for ICRF heating. Fast wave minority heating experiments are planned in D(/sup 3/He) at 8 T and D(H) at 5.5 T. The first antenna will have a single current strap inside a box structure, which will be movable radially. The antenna will be inserted through a side port, making the rf power density on the antenna surface /approximately/2 kW/cm/sup 2/ at 2 MW. The antenna will be center-tapped for mechanical strength and have a double layer Faraday screen tilted along the field lines. The antenna geometry was chosen to maximize power coupling assuming voltage-limited operation. A wide antenna with slotted box sides appears the best design, and 10 /Omega/ of loading is required to couple 2 MW of power at a voltage limit of 40 kV. Matching is achieved by choice of the drive point to a resonant circuit formed by the antenna and a loop of transmission line outside of the vacuum and by tuning elements in the transmission line to the transmitter. 6 refs., 4 figs.

  19. Inversely-designed printed microwave ablation antenna for controlled temperature profile synthesis

    NASA Astrophysics Data System (ADS)

    Sharma, Shashwat; Sarris, Costas D.

    2017-02-01

    Microwave ablation (MWA) is based on localized heating of biological tissues, enabled by an electric field. Antennas for ablation are commonly designed in a forward approach to generate a temperature profile specific to the design. The concept of an inversely-designed MWA antenna, consisting of printed dipoles, is presented herein. This design can be configured to synthesize a desired target temperature profile by controlling and optimizing its current distribution, as demonstrated by simulations. This concept provides the functionality of a phased array on the tip of an interstitial device.

  20. Development of an Ultra-Wideband Circularly Polarized Multiple Layer Dielectric Rod Antenna Design

    NASA Astrophysics Data System (ADS)

    Wainwright, Gregory D.

    This dissertations focuses on the development of a novel Ultra-Wideband (UWB) circularly polarized dielectric rod antenna (CPDRA) which yields a constant gain, pattern, and phase center. These properties are important in many applications. Within radar systems a constant phase center is desirable to avoid errors within downrange and crossrange measurements. In a reflector antenna the illumination, spillover, and phase efficiencies will remain the same over an ultra-wideband. Lastly, near field probes require smooth amplitude and phase patterns over frequency to avoid errors during the calibration process of the antenna under test. In this dissertation a novel CP feeding network has been developed for an ultra-wideband dielectric rod antenna. Circularly-polarized antennas have a major advantage over its linearly-polarized counterpart in that the polarization mismatch loss caused by misalignment between the polarizations of the incident fields and antenna can be avoided. This is important in satellite communications and broadcasts where signal propagation through the ionosphere can experience Faraday Rotation. A circularly polarized antenna is also helpful in mobile radar and communication systems where the receiving antennas orientation is not fixed. Previous research on UWB dielectric rod antenna designs has focused on Dual linear feeds. Each polarization within the dual linear feed is excited by a pair of linear launcher arms fed with a 0°-180° hybrid balun. The proposed CPDRA design does not require the 0°-180° hybrid baluns or 0°-90° hybrid for achieving CP operation. These hybrids will increase the antennas size, weight, cost, and reduce operational bandwidth. A design technique has been developed for an UWB multilayer dielectric waveguide used in a CPDRA antenna. This design technique uses near-field Electric field data from inside the waveguide, in conjunction with a genetic algorithm optimization to yield a wideband waveguide with a near field

  1. Status of the ITER ICRF system design - 'Externally Matched' approach

    SciTech Connect

    Lamalle, P. U.; Dumortier, P.; Durodie, F.; Evrard, M.; Louche, F.; Messiaen, A.; Vervier, M.; Shannon, M.; Borthwick, A.; Chuilon, B.; Nightingale, M.; Goulding, R.; Swain, D.

    2007-09-28

    The design of the ITER ICRF system has been under revision for several years. The paper presents the status of the design proposal based on a 24 strap antenna plug (6 poloidal by 4 toroidal short radiating conductors) in which the straps are passively combined in 8 poloidal triplets by means of 4-port junctions. These triplets are connected in parallel pairwise through matching elements to form 4 load-resilient conjugate-T circuits. All adjustable matching elements are located outside the plug, i.e. in the ITER port cell and in the generator area.

  2. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a patient's...

  3. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a patient's...

  4. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a patient's...

  5. 49 CFR 236.532 - Strap iron inductor; use restricted.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Strap iron inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal Systems Rules and Instructions; Roadway § 236.532 Strap iron inductor; use restricted. No railroad shall use strap iron inductor or other roadway element with...

  6. 49 CFR 236.532 - Strap iron inductor; use restricted.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Strap iron inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal Systems Rules and Instructions; Roadway § 236.532 Strap iron inductor; use restricted. No railroad shall use strap iron inductor or other roadway element with...

  7. 49 CFR 236.532 - Strap iron inductor; use restricted.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Strap iron inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal Systems Rules and Instructions; Roadway § 236.532 Strap iron inductor; use restricted. No railroad shall use strap iron inductor or other roadway element with...

  8. 49 CFR 236.532 - Strap iron inductor; use restricted.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Strap iron inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal Systems Rules and Instructions; Roadway § 236.532 Strap iron inductor; use restricted. No railroad shall use strap iron inductor or other roadway element with...

  9. 49 CFR 236.532 - Strap iron inductor; use restricted.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Strap iron inductor; use restricted. 236.532... Train Stop, Train Control and Cab Signal Systems Rules and Instructions; Roadway § 236.532 Strap iron inductor; use restricted. No railroad shall use strap iron inductor or other roadway element with...

  10. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a...

  11. 21 CFR 868.5560 - Gas mask head strap.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas mask head strap. 868.5560 Section 868.5560...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap. (a) Identification. A gas mask head strap is a device used to hold an anesthetic gas mask in position on a...

  12. 33 CFR 183.532 - Clips, straps, and hose clamps.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Clips, straps, and hose clamps... (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Equipment Standards § 183.532 Clips, straps, and hose clamps. (a) Each clip, strap, and hose clamp must: (1) Be made from a...

  13. 33 CFR 183.532 - Clips, straps, and hose clamps.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Clips, straps, and hose clamps... (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Equipment Standards § 183.532 Clips, straps, and hose clamps. (a) Each clip, strap, and hose clamp must: (1) Be made from a...

  14. Design of an omnidirectional optical antenna for ultraviolet communication.

    PubMed

    Zhang, Xuebin; Tang, Yi; Huang, Heqing; Zhang, Lijun; Bai, Tingzhu

    2014-05-20

    In this paper we propose an omnidirectional large field-optical antenna with a dual-mirror structure and field devices and demonstrate its utilization in ultraviolet (UV) communications. Theoretical analysis shows that it is suitable for short-range UV communication. Simulation indicates that the optical gain is 32, and the system has a good spot uniformity. Additionally, incident angles of incident ray meet the requirement of the interference filter (±10°). Outdoor experiments show that the angle of FOV is in the range of ±20°~±80° and a SNR increase of 31 dB compared with bare tube is observed, demonstrating the effectiveness of the omnidirectional optical antenna structure for free-space UV communication.

  15. Design, dynamic modelling and experimental validation of a 2DOF flexible antenna sensor

    NASA Astrophysics Data System (ADS)

    Castillo, Claudia F.; Naci Engin, Seref; Feliu Batlle, Vicente

    2014-04-01

    A two-degree-of-freedom flexible antenna sensor platform was designed to physically simulate the ability of a robotic arm, which rapidly reorients and targets itself towards specific surfaces from different approachable angles. An accurate antenna model involves non-linear expressions that represent the system dynamics. Therefore, a comprehensive study along with experimental work has been carried out in order to achieve accurate system identification and validate the dynamic model. The model developed has proven useful in controlling the antenna tip, minimising the effects of the non-linear flexural dynamics and the Coulomb friction. The system was driven by servo motors. Algebraic controllers were developed for the antenna tip to track the reference trajectory. The platform system used encoders to measure the joint angles and a loadcell sensor to obtain the flexible link tip position. To validate the sensory information, the results obtained by the integrated sensors were compared to that of an external camera system.

  16. On the design and optimisation of new fractal antenna using PSO

    NASA Astrophysics Data System (ADS)

    Rani, Shweta; Singh, A. P.

    2013-10-01

    An optimisation technique for newly shaped fractal structure using particle swarm optimisation with curve fitting is presented in this article. The aim of particle swarm optimisation is to find the geometry of the antenna for the required user-defined frequency. To assess the effectiveness of the presented method, a set of representative numerical simulations have been done and the results are compared with the measurements from experimental prototypes built according to the design specifications coming from the optimisation procedure. The proposed fractal antenna resonates at the 5.8 GHz industrial, scientific and medical band which is suitable for wireless telemedicine applications. The antenna characteristics have been studied using extensive numerical simulations and are experimentally verified. The antenna exhibits well-defined radiation patterns over the band.

  17. Antennas for the array-based Deep Space Network: current status and future designs

    NASA Technical Reports Server (NTRS)

    Imbriale, William A.; Gama, Eric

    2005-01-01

    Development of very large arrays1,2 of small antennas has been proposed as a way to increase the downlink capability of the NASA Deep Space Network DSN) by two or three orders of magnitude thereby enabling greatly increased science data from currently configured missions or enabling new mission concepts. The current concept is for an array of 400 x 12-m antennas at each of three longitudes. The DSN array will utilize radio astronomy sources for phase calibration and will have wide bandwidth correlation processing for this purpose. NASA has undertaken a technology program to prove the performance and cost of a very large DSN array. Central to that program is a 3-element interferometer to be completed in 2005. This paper describes current status of the low cost 6-meter breadboard antenna to be used as part of the interferometer and the RF design of the 12-meter antenna.

  18. Design and Measurements of a Hybrid RF-MEMS Reconfigurable Loop Antenna on a Flexible Substrate (PREPRINT)

    DTIC Science & Technology

    2010-06-01

    AFRL-RY-WP-TP-2010-1147 DESIGN AND MEASUREMENTS OF A HYBRID RF-MEMS RECONFIGURABLE LOOP ANTENNA ON A FLEXIBLE SUBSTRATE (PREPRINT) Nelson... Antenna on a Flexible Substrate Nelson Sepulveda(1), Dimitrios E. Anagnostou* (2), Rafael A. Rodriguez-Solis(1), and John L. Ebel(3) (1... antenna was designed, fabricated (on a flexible substrate) and measured. The design concepts and measurement results are presented and discussed

  19. Design of an offset fed scanning antenna for the shuttle imaging microwave system. [performance prediction parabolic reflectors and microwave antennas for space shuttles

    NASA Technical Reports Server (NTRS)

    Gustincic, J. J.

    1975-01-01

    A design study is described for a mechanically scanned offset fed parabolic torus reflector antenna having a 4m x 2m aperture for simultaneous use at eleven frequency channels from UHF to millimeter wavelengths. A design for the antenna is presented utilizing dipole and horn feeds at the low frequencies and a Gregorian aberration correcting subreflector system for feeding the torus at the high frequencies. The results and details of a theroetical study based on geometrical optics performed to evaluate the high frequency design and the results of an experimental study involving a one-tenth scale model for evaluation of the low-frequency behavior are given. Beam efficiencies, antenna patterns, beamwidths and cross polarization levels are presented and these results demonstrate that the antenna concept is viable for the Shuttle Imaging Microwave System requirement.

  20. Design of shape memory alloy actuated intelligent parabolic antenna for space applications

    NASA Astrophysics Data System (ADS)

    Kalra, Sahil; Bhattacharya, Bishakh; Munjal, B. S.

    2017-09-01

    The deployment of large flexible antennas is becoming critical for space applications today. Such antenna systems can be reconfigured in space for variable antenna footprint, and hence can be utilized for signal transmission to different geographic locations. Due to quasi-static shape change requirements, coupled with the demand of large deflection, shape memory alloy (SMA) based actuators are uniquely suitable for this system. In this paper, we discuss the design and development of a reconfigurable parabolic antenna structure. The reflector skin of the antenna is vacuum formed using a metalized polycarbonate shell. Two different strategies are chosen for the antenna actuation. Initially, an SMA wire based offset network is formed on the back side of the reflector. A computational model is developed using equivalent coefficient of thermal expansion (ECTE) for the SMA wire. Subsequently, the interaction between the antenna and SMA wire is modeled as a constrained recovery system, using a 1D modified Brinson model. Joule effect based SMA phase transformation is considered for the relationship between input voltage and temperature at the SMA wire. The antenna is modeled using ABAQUS based finite element methodology. The deflection found through the computational model is compared with that measured in experiment. Subsequently, a point-wise actuation system is developed for higher deflection. For power-minimization, an auto-locking device is developed. The performance of the new configuration is compared with the offset-network configuration. It is envisaged that the study will provide a comprehensive procedure for the design of intelligent flexible structures especially suitable for space applications.

  1. System and method of designing a load bearing layer that interfaces to a structural pass-through of an inflatable vessel

    NASA Technical Reports Server (NTRS)

    Spexarth, Gary R. (Inventor)

    2010-01-01

    A method for determining a design of an inflatable module including a rigid member disposed in a restraint layer, wherein the restraint layer includes orthogonal straps, includes modeling a strap adjacent to the rigid member and a strap connected to the rigid member. The adjacent strap and the member strap extend in a first direction. The method further includes selecting a first length of the member strap such that the adjacent strap carries load before the member strap during pressurization of the inflatable module, modeling tensions in the member strap with the first length and the adjacent strap during pressurization of the inflatable model, and outputting the modeled tensions in the member strap with the first length and the adjacent strap. An inflatable module includes a member strap having a length such that an adjacent strap carries load before the member strap during pressurization of the inflatable module.

  2. Testing a Protocol for a Randomized Controlled Trial of Therapeutic versus Placebo Shoulder Strapping as an Adjuvant Intervention Early after Stroke.

    PubMed

    Appel, Caroline; Perry, Lin; Jones, Fiona

    2015-06-01

    This study tested a protocol for a randomized controlled trial of therapeutic versus placebo shoulder strapping as an adjuvant intervention early after stroke. Despite widespread use, there is little evidence of the efficacy or acceptability of shoulder strapping to improve arm function in patients with shoulder paresis following stroke. This study tested a protocol designed to trial shoulder strapping as an adjuvant therapy in patients with shoulder paresis after stroke and tested its acceptability for patients and clinical staff. A multiple-method design comprised one quantitative randomized, double-blind, placebo-controlled study and two qualitative exploratory investigations entailing patient interviews and staff surveys. Seventeen sub-acute stroke patients with shoulder paresis were recruited in London stroke service settings between November 2007 and December 2009. Outcomes from a 4-week therapeutic strapping protocol were compared with those of placebo strapping as an adjunct to conventional rehabilitation. Minimal adverse events and greater improvement in arm function (Action Research Arm Test) were seen with therapeutic compared with placebo strapping (effect size 0.34). Patients and staff found the strapping acceptable with minimal adverse effects. This study provided data for sample size calculation and demonstrated a workable research protocol to investigate the efficacy of shoulder strapping as an adjuvant intervention to routine rehabilitation for stroke patients. Small-scale findings continue to flag the importance of investigating this topic. The protocol is recommended for a definitive trial of shoulder strapping as an adjuvant intervention.

  3. DSN 70-meter antenna microwave optics design and performance improvements. Part 1: Design optimization

    NASA Technical Reports Server (NTRS)

    Bathker, D. A.; Slobin, S. D.

    1989-01-01

    The design optimizations associated with the microwave and structural upgrade of the DSN 64-m antennas are discussed. Expected area efficiency/gain performances at S- and X-band are given for both the original 64-m systems and the upgraded 70-m systems, and error estimates are developed. The DSN 70-m Upgrade Project specifications, based on predesign estimates, were 1.4-dB gain at S-band and 1.9-dB at X-band, with no degradation to critical receiving system noise temperatures. The measurements show an S-band gain increase of 1.9 dB and an average increase of 2.1 dB at X-band. The Project also delivered small receiving system noise decreases at both frequency bands. The three DSN 70-m antennas, in the initial state of mechanical adjustment as of the end of calendar year 1988, are performing with very high peak microwave area efficiencies at very nearly the engineering design expectations of 76 percent at S-band and 71 percent at X-band.

  4. Design and characteristics of a multiband communication satellite antenna system

    NASA Astrophysics Data System (ADS)

    Ueno, Kenji; Itanami, Takao; Kumazawa, Hiroyuki; Ohtomo, Isao

    1995-04-01

    Feasibility studies on a multiband communication satellite antenna system and the key technologies involved in devising this system are described. The proposed multiband communication satellite utilizes four frequency bands: Ka (30/20 GHz), Ku (14/12 GHz), C (6/4 GHz), and S (2.6/2.5 GHz). It has six beam configurations, three multibeam and three shaped-beam. The following key technologies are presented: (1) a low-loss frequency selective subreflector (FSR) for compact feeds, (2) a low-loss and broadband frequency selective surface (FSS), and (3) a highly accurate and reliable mesh reflector.

  5. Design of Dual band Modified Inverted F-Antenna for Military and Intelligent Transportation System (ITS) Applications by Numerical Analysis

    NASA Astrophysics Data System (ADS)

    Hossain, Robiul; Karmokar, Debabrata Kumar

    2012-11-01

    A design of single feed Dual Band Modified Inverted F-Antenna (IFA) operating at 4.45 GHz (4.4-4.7GHz) and 5.9 GHz (5.850-5.925 GHz) has been proposed in this paper. The design is initiated by trial and error method of Numerical Analysis and method of moments (MoMís) in Numerical Electromagnetic code (NEC) is used to design, simulate and analyze this antenna. The results exhibit a proper operation of the antenna in terms of return loss, bandwidth, efficiency, VSWR, and gain at both bands. Proposed antenna is designed to achieve multi-serving purposes. Military applications and applications in the Intelligent Transportation Systems (ITS) are the most important applications within the above mentioned frequency bands respectively. The simulated results including performance parameters of antenna are presented and all are acceptable for the standard antennas.

  6. Metatarsal strapping tightness effect to vertical jump performance.

    PubMed

    Zhang, Yan; Baker, Julien S; Ren, Xuejun; Feng, Neng; Gu, Yaodong

    2015-06-01

    The study investigated the effect of metatarsal strapping on vertical jump performance and evaluated the difference in lower limb kinematics and electromyographic signal (EMG) between different strapping force levels. Twelve male callisthenic athletes completed single vertical jump from a squat posture with hands on hips under three conditions as non-strapping (NS), moderate strapping (MS) and high strapping (HS) round metatarsals. Ground reaction force (GRF) was recorded with KISTLER force platform to calculate the vertical jump height. Angles of ankle, knee and hip were measured with VICON motion analysis system and EMG data were recorded with mega6000 system. Data showed that jump height was significantly higher under HS than NS condition. Compared with NS, ankle inversion decreased significantly during take-off and external rotation increased significantly during landing with MS. Significant difference was also found in the muscle activity of tibialis anterior between non-strapping and strapping conditions.

  7. Nuclear fuel spacer grid with improved outer straps

    SciTech Connect

    De Mario, E.E.; Knott, R.P.

    1986-04-29

    A grid is described for the spacing of fuel rods in a nuclear reactor fuel assembly, comprising: a plurality of interleaved grid straps arranged in an egg-crate configuration defining cells therein for the separate enclosure of each of the fuel rods; and four outer straps attached together in a generally square-shaped array surrounding the heightwise edges of the grid straps. The outer straps each has a central portion and a top and a bottom resilient lengthwise border portion, with the heightwise edges of the grid straps attached to the central portions of their associated outer straps and with the border portions extending vertically beyond and projecting horizontally outwardly beyond their associated central portions of their common outer straps.

  8. Design & Performance of Wearable Ultra Wide Band Textile Antenna for Medical Applications

    NASA Astrophysics Data System (ADS)

    Singh, Nikhil; Singh, Ashutosh Kumar; Singh, Vinod Kumar

    2015-02-01

    The concept of wearable products such as textile antenna are being developed which are capable of monitoring, alerting and demanding attention whenever hospital emergency is needed, hence minimizing labour and resource. In the proposed work by using textile material as a substrate the ultra wideband antenna is designed especially for medical applications.Simulated and measured results here shows that the proposed antenna design meets the requirements of wide working bandwidth and provides 13.08 GHz bandwidth with very small size, washable (if using conductive thread for conductive parts) and flexible materials. Results in terms of bandwidth, radiation pattern, return loss as well as gain and efficiency are presented to validate the usefulness of the current proposed design. The work done here has many implications for future research and it could help patients with such flexible and comfortable medical monitoring techniques.

  9. Design and Experimental Investigation of a Compact Circularly Polarized Integrated Filtering Antenna for Wearable Biotelemetric Devices.

    PubMed

    Jiang, Zhi Hao; Gregory, Micah D; Werner, Douglas H

    2016-04-01

    A compact circularly polarized (CP) integrated filtering antenna is reported for wearable biotelemetric devices in the 2.4 GHz ISM band. The design is based on a mutual synthesis of a CP patch antenna connected to a bandpass filter composed of coupled stripline open-loop resonators, which provides an integrated low-profile radiating and filtering module with a compact form factor of 0.44λ(0)×0.44λ(0)×0.04λ(0). The optimized filtering antenna is fabricated and measured, achieving an S11 < -14 dB, an axial ratio of less than 3 dB and gain higher than 3.5 dBi in the targeted ISM band. With the integrated filtering functionality, the antenna exhibits good out-of-band rejection over an ultra-wide frequency range of 1-6 GHz. Further full-wave simulations and experiments were carried out, verifying that the proposed filtering antenna maintains these desirable properties even when mounted in close proximity to the human body at different positions. The stable impedance performance and the simultaneous wide axial ratio and radiated power beam widths make it an ideal candidate as a wearable antenna for off-body communications. The additional integrated filtering functionality further improves utility by greatly reducing interference and crosstalk with other existing wireless systems.

  10. Global ICRF system designs for ITER and TPX

    NASA Astrophysics Data System (ADS)

    Goulding, R. H.; Hoffman, D. J.; Ryan, P. M.; Durodié, F.

    1996-02-01

    The design of feed networks for ICRF antenna arrays on ITER and TPX are discussed. Features which are present in one or both of the designs include distribution of power to several straps from a single generator, the capability to vary phases of the currents on antenna elements rapidly without the need to rematch, and passive elements which present a nearly constant load to the generators during ELM induced loading transients of a factor of 10 or more. The FDAC (Feedline/Decoupler/Antenna Calculator) network modeling code is described, which allows convenient modeling of the electrical performance of nearly arbitrary ICRF feed networks.

  11. Global ICRF system designs for ITER and TPX

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Ryan, P.M.; Durodie, F.

    1996-02-01

    The design of feed networks for ICRF antenna arrays on ITER and TPX are discussed. Features which are present in one or both of the designs include distribution of power to several straps from a single generator, the capability to vary phases of the currents on antenna elements rapidly without the need to rematch, and passive elements which present a nearly constant load to the generators during ELM induced loading transients of a factor of 10 or more. The FDAC (Feedline/Decoupler/Antenna Calculator) network modeling code is described, which allows convenient modeling of the electrical performance of nearly arbitrary ICRF feed networks. {copyright} {ital 1996 American Institute of Physics.}

  12. Global ICRF system designs for ITER and TPX

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Ryan, P.M.; Durodie, F.

    1995-09-01

    The design of feed networks for ICRF antenna arrays on ITER and TPX are discussed. Features which are present in one or both of the designs include distribution of power to several straps from a single generator, the capability to vary phases of the currents on antenna elements rapidly without the need to rematch, and passive elements which present a nearly constant load to the generators during ELM induced loading transients of a factor of I0 or more. The FDAC (Feedline/Decoupler/Antenna Calculator) network modeling code is described, which allows convenient modeling of the electrical performance of nearly arbitrary ICRF feed networks.

  13. Design, Analysis and Measurement of a Millimeter Wave Antenna Suitable for Stand off Imaging at Checkpoints

    NASA Astrophysics Data System (ADS)

    Gao, Xiang; Li, Chao; Gu, Shengming; Fang, Guangyou

    2011-11-01

    A systematic method is proposed to design a novel beam-scanning antenna with fan-beam, which is suitable for stand off imaging at millimeter wave band. The antenna has not only an elliptical main-reflector to generate thin fan beam, but also a rotating sub-reflector to realize beam scanning function. All these structures are embedded between two parallel metal plates. A Reversed Ray Tracing Algorithm (RRTA) was introduced to optimize the positions and dimensions of the subreflector and the feed horn. A modified Physical Optics method based on Discrete Real Mirror Image theory (DRMI-PO) was developed to efficiently analyze and optimize the field patterns of the antenna with specific structures. Based on above methods, an antenna working at 200 GHz is designed and fabricated. The measured patterns are in well agreement with the calculated results. It's found that, the total beam scanning range is about 60 cm with its minimum half -power beam widths about 1.7 cm in the scanning direction. All the results validate the design method and potential applications of the antenna in the stand off imaging systems.

  14. Precoder Design and Capacity Analysis for Multi-Antenna Full-Duplex Relay

    NASA Astrophysics Data System (ADS)

    Kwak, Young-Woo; Lee, Jong-Ho; Kim, Yong-Hwa; Kim, Seong-Cheol

    In this letter, a precoding design for a multiple-input multiple-output (MIMO) full-duplex relay (FDR) system is proposed. For this system, mitigating the self-interference imposed by the transmit antennas on the receive antennas in the same relay station is crucial for improving the performance of the FDR system. The precoding scheme designed in this study uses block-diagonalization (BD). Using this precoding scheme, FDR capacity analysis is performed in the MIMO downlink relay system. Numerical results on system performance in terms of capacity are shown and discussed.

  15. Beam-waveguide antenna servo design issues for tracking low earth-orbiting satellites

    NASA Technical Reports Server (NTRS)

    Gawronski, W. K.; Mellstrom, J. A.

    1993-01-01

    Upcoming NASA missions will require tracking of low-orbit satellites. As a consequence, NASA antennas will be required to track satellites at higher rates than for the current deep space missions. This article investigates servo design issues for the 34-m beam-waveguide antennas that track low-orbit satellites. This includes upgrading the servo with a feedforward loop, using a monopulse controller design, and reducing tracking errors through either proper choice of elevation pinion location, application of a notch filter, or adjustment of the elevation drive amplifier gain. Finally, improvement of the signal-to-noise ratio through averaging of the over-sampled monopulse signal is described.

  16. Conceptual design and analysis of a large antenna utilizing electrostatic membrane management

    NASA Technical Reports Server (NTRS)

    Brooks, A. L.; Coyner, J. V.; Gardner, W. J.; Mihora, D. J.

    1982-01-01

    Conceptual designs and associated technologies for deployment 100 m class radiometer antennas were developed. An electrostatically suspended and controlled membrane mirror and the supporting structure are discussed. The integrated spacecraft including STS cargo bay stowage and development were analyzed. An antenna performance evaluation was performed as a measure of the quality of the membrane/spacecraft when used as a radiometer in the 1 GHz to 5 GHz region. Several related LSS structural dynamic models differing by their stiffness property (and therefore, lowest modal frequencies) are reported. Control system whose complexity varies inversely with increasing modal frequency regimes are also reported. Interactive computer-aided-design software is discussed.

  17. Design of a low-loss series-fed microstrip array antenna

    NASA Technical Reports Server (NTRS)

    Mahbub, M. R.; Christodoulou. C. G.; Bailey, M. C.

    1998-01-01

    The design and analysis of a series-fed, low-loss, inverted microstrip array antenna, operating at 1.413 GHz is presented. The array antenna is composed of two sub arrays. Each sub array consists of an equal number of microstrip patches all connected together through a series microstrip line. The first element of each sub array is coaxially fed but 180 degree out of phase. This approach ensures a symmetric radiation pattern. The design approach, is accomplished using the IE3D code that utilizes the method of moments. All experimental and simulated data are presented and discussed.

  18. Design of 4x1 microstrip patch antenna array for 5.8 GHz ISM band applications

    NASA Astrophysics Data System (ADS)

    Valjibhai, Gohil Jayesh; Bhatia, Deepak

    2013-01-01

    This paper describes the new design of four element antenna array using corporate feed technique. The proposed antenna array is developed on the Rogers 5880 dielectric material. The antenna array works on 5.8 GHz ISM band. The industrial, scientific and medical (ISM) radio bands are radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than communications. The array antennas have VSWR < 1.6 from 5.725 - 5.875 GHz. The simulated return loss characteristic of the antenna array is - 39.3 dB at 5.8 GHz. The gain of the antenna array is 12.3 dB achieved. The directivity of the broadside radiation pattern is 12.7 dBi at the 5.8 GHz operating frequency. The antenna array is simulated using High frequency structure simulation software.

  19. Design of a compact antenna with flared groundplane for a wearable breast hyperthermia system.

    PubMed

    Curto, Sergio; Prakash, Punit

    2015-01-01

    Currently available microwave hyperthermia systems for breast cancer treatment do not conform to the intact breast and provide limited control of heating patterns, thereby hindering an effective treatment. A compact patch antenna with a flared groundplane that may be integrated within a wearable hyperthermia system for the treatment of the intact breast disease is proposed. A 3D simulation-based approach was employed to optimise the antenna design with the objective of maximising the hyperthermia treatment volume (41 °C iso-therm) while maintaining good impedance matching. The optimised antenna design was fabricated and experimentally evaluated with ex vivo tissue measurements. The optimised compact antenna yielded a -10 dB bandwidth of 90 MHz centred at 915 MHz, and was capable of creating hyperthermia treatment volumes up to 14.4 cm(3) (31 mm × 28 mm × 32 mm) with an input power of 15 W. Experimentally measured reflection coefficient and transient temperature profiles were in good agreement with simulated profiles. Variations of + 50% in blood perfusion yielded variations in the treatment volume up to 11.5%. When compared to an antenna with a similar patch element employing a conventional rectangular groundplane, the antenna with flared groundplane afforded 22.3% reduction in required power levels to reach the same temperature, and yielded 2.4 times larger treatment volumes. The proposed patch antenna with a flared groundplane may be integrated within a wearable applicator for hyperthermia treatment of intact breast targets and has the potential to improve efficiency, increase patient comfort, and ultimately clinical outcomes.

  20. BROADBAND ANTENNA MATCHING NETWORK DESIGN AND APPLICATION FOR RF PLASMA ION SOURCE

    SciTech Connect

    Shin, Ki; Kang, Yoon W; Piller, Chip; Fathy, Aly

    2011-01-01

    The RF ion source at Spallation Neutron Source has been upgraded to meet higher beam power requirement. One important subsystem for efficient operation of the ion source is the 2MHz RF impedance matching network. The real part of the antenna impedance is very small and is affected by plasma density for 2MHz operating frequency. Previous impedance matching network for the antenna has limited tuning capability to cover this potential variation of the antenna impedance since it employed a single tuning element and an impedance transformer. A new matching network with two tunable capacitors has been built and tested. This network can allow precision matching and increase the tunable range without using a transformer. A 5-element broadband matching network also has been designed, built and tested. The 5-element network allows wide band matching up to 50 kHz bandwidth from the resonance center of 2 MHz. The design procedure, simulation and test results are presented.

  1. Analysis And Design Of Antennas Facing Cylindrical Plasma Columns With TOPCYL

    NASA Astrophysics Data System (ADS)

    Guadamuz, S.; Graswinckel, M. F.; Koch, R.; Maggiora, R.; Van De Pol, M.; Vietti, G.; Van Rooij, G.

    2011-12-01

    On recent years TOPICA[1] has shown its capabilities as a designing tool for ICRF antennas on tokamaks, handling both the realistic geometrical detail of the structure as well as a complete description of the plasma region behavior. Now, expanding these capabilities, the TOrino Polythecnic CYLindrical code (TOPCYL) has been added in order to simulate antennas facing cylindrical plasma columns. This feature allows the analysis and design of RF heating systems for applications as VASIMR-like plasma thrusters and plasma-surface-interaction (PSI) experiments. In the present work, the theoretical basis and implementation of TOPCYL is presented, as well as the results obtained on simulating antennas for the ICRF and 2,45 GHz regimes.

  2. Integrated Thermal-structural-electromagnetic Design Optimization of Large Space Antenna Reflectors

    NASA Technical Reports Server (NTRS)

    Adelman, H. M.; Padula, S. L.

    1986-01-01

    The requirements for low mass and high electromagnetic (EM) performance in large, flexible space antenna structures is motivating the development of a systematic procedure for antenna design. In contrast to previous work which concentrated on reducing rms distortions of the reflector surface, thereby indirectly increasing antenna performance, the current work involves a direct approach to increasing electromagnetic performance using mathematical optimization. The thermal, structural, and EM analyses are fully integrated in the context of an optimization procedure, and consequently, the interaction of the various responses is accounted for directly and automatically. Preliminary results are presented for sizing cross-sectional areas of a tetrahedral truss reflector. The results indicate potential for this integrated procedure from the standpoint of mass reduction, performance increase, and efficiency of the design process.

  3. Design and Development of Aerogel-Based Antennas for Aerospace Applications: A Final Report to the NARI Seedling

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Miranda, Felix A.

    2014-01-01

    As highly porous solids possessing low density and low dielectric permittivity combined with good mechanical properties, polyimide (PI) aerogels offer great promise as an enabling technology for lightweight aircraft antenna systems. While they have been aggressively explored for thermal insulation, barely any effort has been made to leverage these materials for antennas or other applications that take advantage of their aforementioned attributes. In Phase I of the NARI Seedling Project, we fabricated PI aerogels with properties tailored to enable new antenna concepts with performance characteristics (wide bandwidth and high gain) and material properties (low density, environmental stability, and robustness) superior to the state of practice (SOP). We characterized electromagnetic properties, including permittivity, reflectivity, and propagation losses for the aerogels. Simple, prototype planar printed circuit patch antennas from down-selected aerogel formulations were fabricated by molding the aerogels to net shapes and by gold-metalizing the pattern onto the templates via electron beam evaporation in a clean room environment. These aerogel based antennas were benchmarked against current antenna SOP, and exhibited both broader bandwidth and comparable or higher gain performance at appreciably lower mass. Phase II focused on the success of the Phase I results pushing the PI aerogel based antenna technology further by exploring alternative antenna design (i.e., slot coupled antennas) and by examining other techniques for fabricating the antennas including ink jet printing with the goal of optimizing antenna performance and simplifying production. We also examined new aerogel formulations with better moisture and solvent resistance to survive processing conditions. In addition, we investigated more complex antenna designs including passive phased arrays such as 2x4 and 4x8 element arrays to assess the scalability of the aerogel antenna concept. Furthermore, we

  4. Design and realization of a planar ultrawideband antenna with notch band at 3.5 GHz.

    PubMed

    Azim, Rezaul; Islam, Mohammad Tariqul; Misran, Norbahiah; Yatim, Baharudin; Arshad, Haslina

    2014-01-01

    A small antenna with single notch band at 3.5 GHz is designed for ultrawideband (UWB) communication applications. The fabricated antenna comprises a radiating monopole element and a perfectly conducting ground plane with a wide slot. To achieve a notch band at 3.5 GHz, a parasitic element has been inserted in the same plane of the substrate along with the radiating patch. Experimental results shows that, by properly adjusting the position of the parasitic element, the designed antenna can achieve an ultrawide operating band of 3.04 to 11 GHz with a notched band operating at 3.31-3.84 GHz. Moreover, the proposed antenna achieved a good gain except at the notched band and exhibits symmetric radiation patterns throughout the operating band. The prototype of the proposed antenna possesses a very compact size and uses simple structures to attain the stop band characteristic with an aim to lessen the interference between UWB and worldwide interoperability for microwave access (WiMAX) band.

  5. Study of shuttle imaging microwave system antenna. Volume 1: Conceptual design

    NASA Technical Reports Server (NTRS)

    Wesley, R. W.; Waineo, D. K.; Barton, C. R.; Love, A. W.

    1975-01-01

    A detailed preliminary design and complete performance evaluation are presented of an 11-channel large aperture scanning radiometer antenna for the shuttle imaging microwave system (SIMS) program. Provisions for interfacing the antenna with the space shuttle orbiter are presented and discussed. A program plan for hardware development and a rough order of magnitude (ROM) cost are also included. The conceptual design of the antenna is presented. It consists of a four-meter diameter parabolic torus main reflector, which is a graphite/epoxy shell supported by a graphite/epoxy truss. A rotating feed wheel assembly supports six Gregorian subreflectors covering the upper eight frequency channels from 6.6 GHz through 118.7 GHz, and two three-channel prime forms feed assemblies for 0.6, 1.4, and 2.7 GHz. The feed wheel assembly also holds the radiometers and power supplies, and a drive system using a 400 Hz synchronous motor is described. The RF analysis of the antenna is performed using physical optics procedures for both the dual reflector Gregorian concept and the single reflector prime focus concept. A unique aberration correcting feed for 2.7 GHz is analyzed. A structural analysis is also included. The analyses indicate that the antenna will meet system requirements.

  6. Hybrid reflection type metasurface of nano-antennas designed for optical needle field generation

    NASA Astrophysics Data System (ADS)

    Wang, Shiyi; Zhan, Qiwen

    2015-03-01

    We propose a reflection type metal-insulator-metal (MIM) metasurface composed of hybrid optical antennas for comprehensive spatial engineering the properties of optical fields. Its capability is illustrated with an example to create a radially polarized vectorial beam for optical needle field generation. Functioning as local quarter-wave-plates (QWP), the MIM metasurface is designed to convert circularly polarized incident into local linear polarization to create an overall radial polarization with corresponding binary phases and desired normalized amplitude modulation ranged from 0.07 to 1. To obtain enough degrees of freedom, the optical-antenna layer comprises periodic arrangements of double metallic nano-bars with perpendicular placement and single nano-bars respectively for different amplitude modulation requirements. Both of the antennas enable to introduce π/2 retardation while reaching the desired modulation range both for phase and amplitude. Through adjusting the antennas' geometry and array carefully, we shift the gap-surface plasmon resonances facilitated by optical antennas to realize the manipulation of vectorial properties. Designed at 1064 nm wavelength, the particularly generated vectorial light output can be further tightly focused by a high numerical aperture objective to obtain longitudinally polarized flat-top focal field. The so-called optical needle field is a promising candidate for novel applications that transcend disciplinary boundaries. The proposed metasurface establishes a new class of compact optical components based on nano-scale structures, leading to compound functions for vectorial light generation.

  7. Design of an HHFW antenna including high impedance surfaces for FTU

    NASA Astrophysics Data System (ADS)

    Milanesio, Daniele; Maggiora, Riccardo

    2013-10-01

    The successful design of an Ion Cyclotron antenna mainly relies on the capability of coupling high power to the plasma (MW), feature that is currently reached by allowing rather high voltages (tens of kV) on the unavoidable unmatched part of the feeding lines. This requirement is often responsible of arcs along the transmission lines and other unwanted phenomena that considerably limit the usage of IC launchers. In this work, we suggest and describe a revolutionary approach based on high impedance surfaces, which allows to increase the antenna radiation efficiency and, hence, to highly reduce the imposed voltages to couple the same level of power to the plasma. High-impedance surfaces are periodic metallic structures (patches) displaced usually on top of a dielectric substrate and grounded by means of vertical posts usually embedded inside the dielectric, in a mushroom-like shape. In terms of working properties, high impedance surfaces are electrically thin in-phase reflectors, i.e. they present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. This work documents the design by means of numerical codes of an antenna including high impedance surfaces to be tested on the FTU IBW port and fed by the FTU IBW generators at 433 MHz. The test on FTU, if successful, will confirm the possibility to adopt this approach for future HHFW antennas.

  8. A new design of an S/X dual band circular slot antenna for radar applications.

    PubMed

    Ghnimi, Said; Wali, Rawia; Gharsallh, Ali; Razban, Tchanguiz

    2013-01-01

    A novel design of dual-band slot antenna with a circular patch for radar applications is presented and studied. It is fed by a micro-strip line and built on a FR-4 substrate with a whole size of 18 x 30 mm2. A dual band printed antenna is created by introducing slots on the radiating element. By this, two bandwidth, covering C and X band, are achieved. In order to obtain a good fundamental antenna design, the initial studies were carried out theoretically, using CST Microwave Studio simulation software. In this case, the frequency range at return loss < 10 dB is 5.24 - 6.16 GHz for low frequency and is 7.9 -11.7 GHz for high frequency. In addition, the proposed antenna has good radiation characteristics and stable gains over the whole operating bands. A prototype of antenna is fabricated and tested. Experimental data show good agreement between simulated and measured results.

  9. Design method for an offset dual-shaped reflector antenna with high efficiency and an elliptical beam

    NASA Astrophysics Data System (ADS)

    Aoki, K.; Makino, S.; Katagi, T.; Kagoshima, K.

    1993-04-01

    A newly developed method of design for a shaped reflector antenna is described. A conventional quadratic reflector configuration is assumed; the reflectors are then modified to yield the desired aperture shape and field distribution by introducing shaping functions. This method is useful for designing antennas with an arbitrary shaped beam, such as an elliptical-beam antenna, and has been verified through a 4.7 m x 2.3 m dual-band earth-station antenna for the Japanese domestic satellite system CS. The measured aperture efficiency is more than 76 percent, and the ratio of the major and minor axes of the elliptical beam is 2:1.

  10. Field-Aligned ICRF Antenna Characterization and Performance in Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Wukitch, Stephen

    2012-10-01

    Impurity contamination associated with ion cyclotron range of frequency (ICRF) heating remains a major challenge to ICRF utilization in magnetic confinement devices, particularly with metallic plasma facing components. Here, we report results on an experimental investigation of a high power, magnetic field-aligned (FA) antenna, designed to reduce parallel electric (E||) field through symmetry and thereby reduce RF related impurity contamination. Using the standard non-field aligned antennas (ST) as a reference, the impurity contamination and sources on the antenna are significantly lower for the FA-antenna than the ST antennas. In addition, the radiated power is reduced for given injected power for the FA-antenna compared to the ST-antennas in L and H-mode discharges. The improved performance is consistent with simulations indicating that the FA-antenna has reduced integrated E|| relative to the non-aligned antennas. However, the simulation also predicts that so-called monopole phasing, where antenna strap current has [0,0,0,0] phase, should have the lowest integrated E||. The initial results suggest that monopole phasing has a stronger impact on the plasma potential and higher core impurity contamination and sources at the antenna. Utilizing gas puff imaging, the radial electric field profile in the scrape-off-layer (SOL) is readily measured. For the ST and FA-antennas, fine structure (variations of order ˜0.5 cm) in the radial electric field is observed and radial penetration of the rectified potential structures is ˜10 times greater than the skin depth. This anomalous penetration appears to be consistent with including cross-field RF polarization currents in the sheath model. Further comparisons of the FA- and ST-antennas are being carried out with an extensive array of boundary plasma diagnostics to characterize the impurity behavior and impact on the SOL transport and SOL density profiles; the latest results will be presented.

  11. Mitigating Multipath Bias Using a Dual-Polarization Antenna: Theoretical Performance, Algorithm Design, and Simulation.

    PubMed

    Xie, Lin; Cui, Xiaowei; Zhao, Sihao; Lu, Mingquan

    2017-02-13

    It is well known that multipath effect remains a dominant error source that affects the positioning accuracy of Global Navigation Satellite System (GNSS) receivers. Significant efforts have been made by researchers and receiver manufacturers to mitigate multipath error in the past decades. Recently, a multipath mitigation technique using dual-polarization antennas has become a research hotspot for it provides another degree of freedom to distinguish the line-of-sight (LOS) signal from the LOS and multipath composite signal without extensively increasing the complexity of the receiver. Numbers of multipath mitigation techniques using dual-polarization antennas have been proposed and all of them report performance improvement over the single-polarization methods. However, due to the unpredictability of multipath, multipath mitigation techniques based on dual-polarization are not always effective while few studies discuss the condition under which the multipath mitigation using a dual-polarization antenna can outperform that using a single-polarization antenna, which is a fundamental question for dual-polarization multipath mitigation (DPMM) and the design of multipath mitigation algorithms. In this paper we analyze the characteristics of the signal received by a dual-polarization antenna and use the maximum likelihood estimation (MLE) to assess the theoretical performance of DPMM in different received signal cases. Based on the assessment we answer this fundamental question and find the dual-polarization antenna's capability in mitigating short delay multipath-the most challenging one among all types of multipath for the majority of the multipath mitigation techniques. Considering these effective conditions, we propose a dual-polarization sequential iterative maximum likelihood estimation (DP-SIMLE) algorithm for DPMM. The simulation results verify our theory and show superior performance of the proposed DP-SIMLE algorithm over the traditional one using only an RHCP

  12. The Design and Evaluation of Transmit and Receive Antennas for an Ionospheric Communications Probe System: A. Multiband Dipole Antenna

    DTIC Science & Technology

    1992-12-01

    RECEIVE ANTENNAS FOR AN IONOSPHERIC COMMUNICATIONS PROBE SYSTEM: A. MULTIBAND DIPOLE ANTENNA by Sotirios Georgios Perros December, 1992 Thesis Advisor...PROBE SYSTEM: A. MULTIBANDDIPOLE ANTENNA 12 PERSONAL AUTHOR(S) PERROS , Sotirios Georgios 13a TYPE OF REPORT 13b TIME COVERED 14 DATE OF REPORT (Year...Sotirios Georgios Perros By Lieutenant, Hellenic Navy Dist! ibution I B.S., Hellenic Naval Academy, 1984 Availabiity des Avail i•,(lior Submitted in

  13. Module strap tests and how they effect the 25 cm stack construction

    SciTech Connect

    Hill, N.F.

    1994-09-06

    We were asked at the previous Atlas collaboration meeting to confirm our proposal that the Argonne design option could maintain the tie straps in a prestressed condition after welding. This was deemed necessary to maintain compression loading of the steel plate stack. The compression load requirement was set at a load equivalent to that necessary to maintain continuity of the stack using friction. We will attempt to prove that through the strap testing and the ultimate construction of the 25 cm prototype stack that we have in fact met these requirements.

  14. Inflatable Antenna for CubeSat: Extension of the Previously Developed S-Band Design to the X-Band

    NASA Technical Reports Server (NTRS)

    Babuscia, Alessandra; Choi, Thomas; Cheung, Kar-Ming; Thangavelautham, Jekan; Ravichandran, Mithun; Chandra, Aman

    2015-01-01

    The inflatable antenna for CubeSat is a 1 meter antenna reflector designed with one side reflective Mylar, another side clear Mylar with a patch antenna at the focus. The development of this technology responds to the increasing need for more capable communication systems to allow CubeSats to operate autonomously in interplanetary missions. An initial version of the antenna for the S-Band was developed and tested in both anechoic chamber and vacuum chamber. Recent developments in transceivers and amplifiers for CubeSat at X-band motivated the extension from the S-Band to the X-Band. This paper describes the process of extending the design of the antenna to the X-Band focusing on patch antenna redesign, new manufacturing challenges and initial results of experimental tests.

  15. Metasurface Reflector (MSR) Loading for High Performance Small Microstrip Antenna Design.

    PubMed

    Ahsan, Md Rezwanul; Islam, Mohammad Tariqul; Ullah, Mohammad Habib; Singh, Mandeep Jit; Ali, Mohd Tarmizi

    2015-01-01

    A meander stripline feed multiband microstrip antenna loaded with metasurface reflector (MSR) structure has been designed, analyzed and constructed that offers the wireless communication services for UHF/microwave RFID and WLAN/WiMAX applications. The proposed MSR assimilated antenna comprises planar straight forward design of circular shaped radiator with horizontal slots on it and 2D metasurface formed by the periodic square metallic element that resembles the behavior of metamaterials. A custom made high dielectric bio-plastic substrate (εr = 15) is used for fabricating the prototype of the MSR embedded planar monopole antenna. The details of the design progress through numerical simulations and experimental results are presented and discussed accordingly. The measured impedance bandwidth, radiation patterns and gain of the proposed MSR integrated antenna are compared with the obtained results from numerical simulation, and a good compliance can be observed between them. The investigation shows that utilization of MSR structure has significantly broadened the -10 dB impedance bandwidth than the conventional patch antenna: from 540 to 632 MHz (17%), 467 to 606 MHz (29%) and 758 MHz to 1062 MHz (40%) for three distinct operating bands centered at 0.9, 3.5 and 5.5 GHz. Additionally, due to the assimilation of MSR, the overall realized gains have been upgraded to a higher value of 3.62 dBi, 6.09 dBi and 8.6 dBi for lower, middle and upper frequency band respectively. The measured radiation patterns, impedance bandwidths (S11<-10 dB) and gains from the MSR loaded antenna prototype exhibit reasonable characteristics that can satisfy the requirements of UHF/microwave (5.8 GHz) RFID, WiMAX (3.5/5.5 GHz) and WLAN (5.2/5.8 GHz) applications.

  16. Metasurface Reflector (MSR) Loading for High Performance Small Microstrip Antenna Design

    PubMed Central

    Ahsan, Md Rezwanul; Islam, Mohammad Tariqul; Ullah, Mohammad Habib; Singh, Mandeep Jit; Ali, Mohd Tarmizi

    2015-01-01

    A meander stripline feed multiband microstrip antenna loaded with metasurface reflector (MSR) structure has been designed, analyzed and constructed that offers the wireless communication services for UHF/microwave RFID and WLAN/WiMAX applications. The proposed MSR assimilated antenna comprises planar straight forward design of circular shaped radiator with horizontal slots on it and 2D metasurface formed by the periodic square metallic element that resembles the behavior of metamaterials. A custom made high dielectric bio-plastic substrate (εr = 15) is used for fabricating the prototype of the MSR embedded planar monopole antenna. The details of the design progress through numerical simulations and experimental results are presented and discussed accordingly. The measured impedance bandwidth, radiation patterns and gain of the proposed MSR integrated antenna are compared with the obtained results from numerical simulation, and a good compliance can be observed between them. The investigation shows that utilization of MSR structure has significantly broadened the -10dB impedance bandwidth than the conventional patch antenna: from 540 to 632 MHz (17%), 467 to 606 MHz (29%) and 758 MHz to 1062 MHz (40%) for three distinct operating bands centered at 0.9, 3.5 and 5.5 GHz. Additionally, due to the assimilation of MSR, the overall realized gains have been upgraded to a higher value of 3.62 dBi, 6.09 dBi and 8.6 dBi for lower, middle and upper frequency band respectively. The measured radiation patterns, impedance bandwidths (S11<-10 dB) and gains from the MSR loaded antenna prototype exhibit reasonable characteristics that can satisfy the requirements of UHF/microwave (5.8 GHz) RFID, WiMAX (3.5/5.5 GHz) and WLAN (5.2/5.8 GHz) applications. PMID:26018795

  17. Miniaturized differentially fed dual-band implantable antenna: Design, realization, and in vitro test

    NASA Astrophysics Data System (ADS)

    Lei, Wen; Guo, Yong-Xin

    2015-10-01

    A differentially fed dual-band implantable antenna is designed in this paper, with an additional shorting strip to achieve a size reduction. The antenna has been simulated by using one-layer and multilayer tissue models and a human anatomical model. The prototype model is fabricated and in vitro demonstrated with skin-mimicking phantoms, which experimentally achieves impedance bandwidths of 32 MHz at 401-406 MHz Medical Device Radiocommunications Service band and 151 MHz at 2.4-2.48 GHz Industrial, Scientific, and Medical band. Radiation characteristic has been evaluated in Computer Simulation Technology (CST) human voxel model.

  18. Optimum design of antennas using metamaterials with the efficient global optimization (EGO) algorithm

    NASA Astrophysics Data System (ADS)

    Southall, Hugh L.; O'Donnell, Teresa H.; Derov, John S.

    2010-04-01

    EGO is an evolutionary, data-adaptive algorithm which can be useful for optimization problems with expensive cost functions. Many antenna design problems qualify since complex computational electromagnetics (CEM) simulations can take significant resources. This makes evolutionary algorithms such as genetic algorithms (GA) or particle swarm optimization (PSO) problematic since iterations of large populations are required. In this paper we discuss multiparameter optimization of a wideband, single-element antenna over a metamaterial ground plane and the interfacing of EGO (optimization) with a full-wave CEM simulation (cost function evaluation).

  19. A liquid metal-based structurally embedded vascular antenna: II. Multiobjective and parameterized design exploration

    NASA Astrophysics Data System (ADS)

    Hartl, D. J.; Frank, G. J.; Malak, R. J.; Baur, J. W.

    2017-02-01

    Research on the structurally embedded vascular antenna concept leverages past efforts on liquid metal (LM) reconfigurable electronics, microvascular composites, and structurally integrated and reconfigurable antennas. Such a concept has potential for reducing system weight or volume while simultaneously allowing in situ adjustment of resonant frequencies and/or changes in antenna directivity. This work considers a microvascular pattern embedded in a laminated composite and filled with LM. The conductive liquid provides radio frequency (RF) functionality while also allowing self-cooling. Models describing RF propagation and heat transfer, in addition to the structural effects of both the inclusion of channels and changes in temperature, were described in part 1 of this two-part work. In this part 2, the engineering models developed and demonstrated in part 1 toward the initial exploration of design trends are implemented into multiple optimization frameworks for more detailed design studies, one of which being novel and particularly applicable to this class of problem. The computational expense associated with the coupled multiphysical analysis of the structurally embedded LM transmitting antenna motivates the consideration of surrogate-based optimization methods. Both static and adaptive approaches are explored; it is shown that iteratively correcting the surrogate leads to more accurate optimized design predictions. The expected strong dependence of antenna performance on thermal environment motivates the consideration of a novel ‘parameterized’ optimization approach that simultaneously calculates whole families of optimal designs based on changes in design or operational variables generally beyond the control of the designer. The change in Pareto-optimal response with evolution in operating conditions is clearly demonstrated.

  20. Design options for an ITER ion cyclotron system

    NASA Astrophysics Data System (ADS)

    Swain, D. W.; Baity, F. W.; Bigelow, T. S.; Ryan, P. M.; Goulding, R. H.; Carter, M. D.; Stallings, D. C.; Batchelor, D. B.; Hoffman, D. J.

    1996-02-01

    Recent changes have occurred in the design requirements for the ITER ion cyclotron system, requiring in-port launchers in four main horizontal ports to deliver 50 MW of power to the plasma. The design is complicated by the comparatively large antenna-separatrix distance of 10-20 cm. Designs of a conventional strap launcher and a folded waveguide launcher that can meet the new requirements are presented.

  1. Design options for an ITER ion cyclotron system

    SciTech Connect

    Swain, D.W.; Baity, F.W.; Bigelow, T.S.; Ryan, P.M.; Goulding, R.H.; Carter, M.D.; Stallings, D.C.; Batchelor, D.B.; Hoffman, D.J.

    1995-09-01

    Recent changes have occurred in the design requirements for the ITER ion cyclotron system, requiring in-port launchers in four main horizontal ports to deliver 50 MW of power to the plasma. The design is complicated by the comparatively large antenna-separatrix distance of 10--20 cm. Designs of a conventional strap launcher and a folded waveguide launcher than can meet the new requirements are presented.

  2. Low-cost dielectric substrate for designing low profile multiband monopole microstrip antenna.

    PubMed

    Ahsan, M R; Islam, M T; Habib Ullah, M; Arshad, H; Mansor, M F

    2014-01-01

    This paper proposes a small sized, low-cost multiband monopole antenna which can cover the WiMAX bands and C-band. The proposed antenna of 20 × 20 mm(2) radiating patch is printed on cost effective 1.6 mm thick fiberglass polymer resin dielectric material substrate and fed by 4 mm long microstrip line. The finite element method based, full wave electromagnetic simulator HFSS is efficiently utilized for designing and analyzing the proposed antenna and the antenna parameters are measured in a standard far-field anechoic chamber. The experimental results show that the prototype of the antenna has achieved operating bandwidths (voltage stand wave ratio (VSWR) less than 2) 360 MHz (2.53-2.89 GHz) and 440 MHz (3.47-3.91 GHz) for WiMAX and 1550 MHz (6.28-7.83 GHz) for C-band. The simulated and measured results for VSWR, radiation patterns, and gain are well matched. Nearly omnidirectional radiation patterns are achieved and the peak gains are of 3.62 dBi, 3.67 dBi, and 5.7 dBi at 2.66 GHz, 3.65 GHz, and 6.58 GHz, respectively.

  3. Low-Cost Dielectric Substrate for Designing Low Profile Multiband Monopole Microstrip Antenna

    PubMed Central

    Ahsan, M. R.; Islam, M. T.; Habib Ullah, M.; Arshad, H.; Mansor, M. F.

    2014-01-01

    This paper proposes a small sized, low-cost multiband monopole antenna which can cover the WiMAX bands and C-band. The proposed antenna of 20 × 20 mm2 radiating patch is printed on cost effective 1.6 mm thick fiberglass polymer resin dielectric material substrate and fed by 4 mm long microstrip line. The finite element method based, full wave electromagnetic simulator HFSS is efficiently utilized for designing and analyzing the proposed antenna and the antenna parameters are measured in a standard far-field anechoic chamber. The experimental results show that the prototype of the antenna has achieved operating bandwidths (voltage stand wave ratio (VSWR) less than 2) 360 MHz (2.53–2.89 GHz) and 440 MHz (3.47–3.91 GHz) for WiMAX and 1550 MHz (6.28–7.83 GHz) for C-band. The simulated and measured results for VSWR, radiation patterns, and gain are well matched. Nearly omnidirectional radiation patterns are achieved and the peak gains are of 3.62 dBi, 3.67 dBi, and 5.7 dBi at 2.66 GHz, 3.65 GHz, and 6.58 GHz, respectively. PMID:25136648

  4. Computer-aided design of reflector antennas - The Green Bank Radio Telescope

    NASA Astrophysics Data System (ADS)

    Terada, Marco A. B.; Stutzman, Warren L.

    1998-03-01

    This paper presents an evaluation of the electrical performance of the Green Bank Telescope (GBT) reflector antenna, operating as single- and dual-offset configurations, as well as a general overview of the GBT system. The GBT dual-offset Gregorian configuration is designed for low cross polarization (XPOL) using the dual-offset reflector antenna (DORA) synthesis package code. The procedure implemented in DORA to upgrade an existing main reflector to a low cross-polarized dual-offset Gregorian reflector antenna is also described. All computed patterns were obtained with the parabolic reflector analysis code (PRAC) program, and with the commercial code GRASP7. The GBT radiation patterns and performance values indicate that low XPOL performance can be achieved with a dual-offset configuration, provided that a low XPOL feed is used. The GBT configuration is employed as a case example for the aforementioned procedure.

  5. Optimization of a conical antenna for pulse radiation - An efficient design using resistive loading

    NASA Astrophysics Data System (ADS)

    Maloney, James G.; Smith, Glenn S.

    1993-07-01

    The conical monopole antenna with a section of continuous resistive loading is considered as a radiator for temporally short, broad-bandwidth pulses. The geometrical details of the coaxial feed and the resistive loading are varied to optimize this structure for pulse radiation. Compared with the perfectly conducting cone, the optimized resistive cone radiates a better reproduction of the pulse excitation with no loss in amplitude, and has internal reflections that are much smaller in amplitude. Graphical displays of the field surrounding the antenna are used to give insight into the physical processes for transient radiation from this antenna. Experimental models were constructed to verify the optimization and demonstrate the practicality of the design. Measurements of both the reflected voltage in the feed line and the time-varying radiated field are in excellent agreement with the theoretical calculations.

  6. Design Method for a Low-Profile Dual-Shaped Reflector Antenna with an Elliptical Aperture by the Suppression of Undesired Scattering

    NASA Astrophysics Data System (ADS)

    Inasawa, Yoshio; Kuroda, Shinji; Kusakabe, Kenji; Naito, Izuru; Konishi, Yoshihiko; Makino, Shigeru; Tsuchiya, Makio

    A design method is proposed for a low-profile dual-shaped reflector antenna for the mobile satellite communications. The antenna is required to be low-profile because of mount restrictions. However, reduction of its height generally causes degradation of antenna performance. Firstly, an initial low-profile reflector antenna with an elliptical aperture is designed by using Geometrical Optics (GO) shaping. Then a Physical Optics (PO) shaping technique is applied to optimize the gain and sidelobes including mitigation of undesired scattering. The developed design method provides highly accurate design procedure for electrically small reflector antennas. Fabrication and measurement of a prototype antenna support the theory.

  7. Implementation of the new multichannel X-mode edge density profile reflectometer for the ICRF antenna on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Aguiam, D. E.; Silva, A.; Bobkov, V.; Carvalho, P. J.; Carvalho, P. F.; Cavazzana, R.; Conway, G. D.; D'Arcangelo, O.; Fattorini, L.; Faugel, H.; Fernandes, A.; Fünfgelder, H.; Gonçalves, B.; Guimarais, L.; De Masi, G.; Meneses, L.; Noterdaeme, J. M.; Pereira, R. C.; Rocchi, G.; Santos, J. M.; Tuccillo, A. A.; Tudisco, O.

    2016-11-01

    A new multichannel frequency modulated continuous-wave reflectometry diagnostic has been successfully installed and commissioned on ASDEX Upgrade to measure the plasma edge electron density profile evolution in front of the Ion Cyclotron Range of Frequencies (ICRF) antenna. The design of the new three-strap ICRF antenna integrates ten pairs (sending and receiving) of microwave reflectometry antennas. The multichannel reflectometer can use three of these to measure the edge electron density profiles up to 2 × 1019 m-3, at different poloidal locations, allowing the direct study of the local plasma layers in front of the ICRF antenna. ICRF power coupling, operational effects, and poloidal variations of the plasma density profile can be consistently studied for the first time. In this work the diagnostic hardware architecture is described and the obtained density profile measurements were used to track outer radial plasma position and plasma shape.

  8. Implementation of the new multichannel X-mode edge density profile reflectometer for the ICRF antenna on ASDEX Upgrade

    SciTech Connect

    Aguiam, D. E. Silva, A.; Carvalho, P. J.; Carvalho, P. F.; Fernandes, A.; Gonçalves, B.; Guimarais, L.; Meneses, L.; Pereira, R. C.; Santos, J. M.; Bobkov, V.; Conway, G. D.; Faugel, H.; Fünfgelder, H.; Cavazzana, R.; De Masi, G.; D’Arcangelo, O.; Rocchi, G.; Tuccillo, A. A.; and others

    2016-11-15

    A new multichannel frequency modulated continuous-wave reflectometry diagnostic has been successfully installed and commissioned on ASDEX Upgrade to measure the plasma edge electron density profile evolution in front of the Ion Cyclotron Range of Frequencies (ICRF) antenna. The design of the new three-strap ICRF antenna integrates ten pairs (sending and receiving) of microwave reflectometry antennas. The multichannel reflectometer can use three of these to measure the edge electron density profiles up to 2 × 10{sup 19} m{sup −3}, at different poloidal locations, allowing the direct study of the local plasma layers in front of the ICRF antenna. ICRF power coupling, operational effects, and poloidal variations of the plasma density profile can be consistently studied for the first time. In this work the diagnostic hardware architecture is described and the obtained density profile measurements were used to track outer radial plasma position and plasma shape.

  9. Electrical Design of an ICRF System for Ignitor

    NASA Astrophysics Data System (ADS)

    Maggiora, R.; Vecchi, G.; Riccitelli, M.; Carter, M. D.

    1996-11-01

    A system of 6 antennae is designed for ion cyclotron resonance heating (ICRH) in Ignitor. The coupling properties of each antenna are calculated by using a two-dimensional slab model to obtain the parameters necessary to model the current strap as a trasmission line then using the calculated current profile in a three-dimensional simulation (the codes have been developed at ORNL). The antenna consists of 4 loop (straps) to form a 2×2 poloidal and toroidal phased array; in our proposal each strap is fed by a coaxial cable, an adapter and a RF power generator. The power spectrum of the radiated parallel index is optimized for out-of-phasing in order to obtain a high heating efficiency and a high loading resistance. The predicted loading and "effective" resistance is sufficient for ICRH experiments with 4.0 MW of power injected in the plasma by each antenna as long as the distance between the Faraday shield and plasma separatrix surface is smaller than 4.0 cm. The maximum RF voltage in the system is 50.0 kV which is limited by generator power and coaxial cable dimensions. The development of a self-consistent integral-equation code is presently under way to analyze geometry effects on the antenna performances. Sponsored by ENEA, CNR, and ASP of Italy, and by the US DoE

  10. Scattering from thin dielectric straps surrounding a perfectly conducting structure

    NASA Technical Reports Server (NTRS)

    Al-Hekail, Zeyad; Gupta, Inder J.

    1989-01-01

    A method to calculate the electromagnetic scattered fields from a dielectric strap wrapped around convex, conducting structure is presented. A moment method technique is used to find the current excited within the strap by the incident plane wave. Then, Uniform Geometrical Theory of Diffraction (UTD) is used to compute the fields scattered by the strap. Reasonable agreement was obtained between the computed and the measured results. The results found in this study are useful in evaluating straps as a target support structure for scattering measurements.

  11. Scattering from thin dielectric straps surrounding a perfectly conducting structure

    NASA Technical Reports Server (NTRS)

    Al-Hekail, Zeyad O.; Gupta, Inder J.; Burnside, Walter D.

    1993-01-01

    Dielectric straps can support very heavy targets and have low backscattering levels, especially at low frequencies (below 8 GHz); thus, they can be used effectively to support targets during backscattered field measurements. In this paper, the scattered fields of nonmagnetic dielectric straps surrounding a perfectly conducting structure are presented, and the computed results are compared with experimental data. Empirical formulas for the strap scattered fields are also given. These formulas are good for general convex structures whose radii of curvature are large compared with the wavelength and are expected to give a reasonable estimate of the true backscattered fields from the dielectric straps when used as a target support structure.

  12. Scattering from thin dielectric straps surrounding a perfectly conducting structure

    NASA Technical Reports Server (NTRS)

    Al-Hekail, Zeyad O.; Gupta, Inder J.; Burnside, Walter D.

    1993-01-01

    Dielectric straps can support very heavy targets and have low backscattering levels, especially at low frequencies (below 8 GHz); thus, they can be used effectively to support targets during backscattered field measurements. In this paper, the scattered fields of nonmagnetic dielectric straps surrounding a perfectly conducting structure are presented, and the computed results are compared with experimental data. Empirical formulas for the strap scattered fields are also given. These formulas are good for general convex structures whose radii of curvature are large compared with the wavelength and are expected to give a reasonable estimate of the true backscattered fields from the dielectric straps when used as a target support structure.

  13. The design and development of two-failure tolerant mechanisms for the Spaceborne Imaging Radar (SIR-B) antenna

    NASA Technical Reports Server (NTRS)

    Presas, S. J.

    1984-01-01

    The performance requirements, design constraints, and design qualification status of the mechanisms necessary to restrain, deploy, and stow the Spaceborne Imaging Radar (SIR) B antenna experiment on the Shuttle Orbiters are described.

  14. Design and Analysis of Miniaturized Microstrip Patch Antenna with Metamaterials Based on Modified Split-Ring Resonator for UWB Applications

    NASA Astrophysics Data System (ADS)

    Khedrouche, D.; Bougoutaia, T.; Hocini, A.

    2016-11-01

    In this paper, a miniaturized microstrip patch antenna using a negative index metamaterial with modified split-ring resonator (SRR) unit cells is proposed for ultra-wideband (UWB) applications. The new design of metamaterial based microstrip patch antenna has been optimized to provide an improved bandwidth and multiple frequency operations. All the antenna performance parameters are presented in response-graphs. Also it is mentioned that the physical dimensions of the metamaterial based patch antenna are very small, which is convenient to modern communication. A 130 % bandwidth, covering the frequency band of 2.9-13.5 GHz, (for return loss less than or equal -10 dB) is achieved, which allow the antenna to operate in the Federal Communication Commission (FCC) band. In addition, the antenna has a good radiation pattern in the ultra-wide band spectrum, and it is nearly omnidirectional.

  15. Conceptual design studies of the 5 m terahertz antenna for Dome A, Antarctica

    NASA Astrophysics Data System (ADS)

    Yang, Ji; Zuo, Ying-Xi; Lou, Zheng; Cheng, Jing-Quan; Zhang, Qi-Zhou; Shi, Sheng-Cai; Huang, Jia-Sheng; Yao, Qi-Jun; Wang, Zhong

    2013-12-01

    As the highest, coldest and driest place in Antarctica, Dome A provides exceptionally good observing conditions for ground-based observations over terahertz wavebands. The 5 m Dome A Terahertz Explorer (DATE5) has been proposed to explore new terahertz windows, primarily over wavelengths between 350 and 200 μm. DATE5 will be an open-air, fully-steerable telescope that can function by unmanned operation with remote control. The telescope will be able to endure the harsh polar environment, including high altitude, very low temperature and very low air pressure. The unique specifications, including high accuracies for surface shape and pointing and fully automatic year-around remote operation, along with a stringent limit on the periods of on-site assembly, testing and maintenance, bring a number of challenges to the design, construction, assembly and operation of this telescope. This paper introduces general concepts related to the design of the DATE5 antenna. Beginning from an overview of the environmental and operational limitations, the design specifications and requirements of the DATE5 antenna are listed. From these, major aspects on the conceptual design studies, including the antenna optics, the backup structure, the panels, the subreflector, the mounting and the antenna base structure, are explained. Some critical issues of performance are justified through analyses that use computational fluid dynamics, thermal analysis and de-icing studies, and the proposed approaches for test operation and on-site assembly. Based on these studies, we conclude that the specifications of the DATE5 antenna can generally be met by using enhanced technological approaches.

  16. Design considerations for the beam-waveguide retrofit of a ground antenna station

    NASA Technical Reports Server (NTRS)

    Veruttipong, T.; Withington, J.; Galindo-Israel, V.; Imbriale, W.; Bathker, D.

    1986-01-01

    Retrofitting an antenna that was originally designed without a beam waveguide introduces special difficulties because it is desirable to minimize alteration of the original mechanical truss work and to image the actual feed without distortion at the focal point of the dual-shaped reflector. To obtain an acceptable image, certain Geometrical Optics (GO) design criteria are followed as closely as possible. The problems associated with applying these design criteria to a 34-meter dual-shaped DSN (Deep Space Network) antenna are discussed. The use of various diffraction analysis techniques in the design process is also discussed. GTD and FFT algorithms are particularly necessary at the higher frequencies, while Physical Optics and Spherical Wave Expansions proved necessary at the lower frequencies.

  17. Exact mesh shape design of large cable-network antenna reflectors with flexible ring truss supports

    NASA Astrophysics Data System (ADS)

    Liu, Wang; Li, Dong-Xu; Yu, Xin-Zhan; Jiang, Jian-Ping

    2014-04-01

    An exact-designed mesh shape with favorable surface accuracy is of practical significance to the performance of large cable-network antenna reflectors. In this study, a novel design approach that could guide the generation of exact spatial parabolic mesh configurations of such reflector was proposed. By incorporating the traditional force density method with the standard finite element method, this proposed approach had taken the deformation effects of flexible ring truss supports into consideration, and searched for the desired mesh shapes that can satisfy the requirement that all the free nodes are exactly located on the objective paraboloid. Compared with the conventional design method, a remarkable improvement of surface accuracy in the obtained mesh shapes had been demonstrated by numerical examples. The present work would provide a helpful technical reference for the mesh shape design of such cable-network antenna reflector in engineering practice. [Figure not available: see fulltext.

  18. Integrated design and simulation for millimeter-wave antenna systems

    NASA Technical Reports Server (NTRS)

    Cwik, T.; Katz, D. S.; Villegas, F. J.

    2000-01-01

    In this paper the development and application of MODTool (Millimeter-wave Optics Design), a design tool that efficiently integrates existing millimeter-wave optics design software with a solid body modeler and thermal/structural analysis packages, will be discussed.

  19. Integrated design and simulation for millimeter-wave antenna systems

    NASA Technical Reports Server (NTRS)

    Cwik, T.; Katz, D. S.; Villegas, F. J.

    2000-01-01

    In this paper the development and application of MODTool (Millimeter-wave Optics Design), a design tool that efficiently integrates existing millimeter-wave optics design software with a solid body modeler and thermal/structural analysis packages, will be discussed.

  20. The design, development and qualification of a lightweight antenna pointing mechanism

    NASA Technical Reports Server (NTRS)

    Shmulevitz, M.; Halsband, A.

    1996-01-01

    This paper describes the design, development, and qualification of a new lightweight and compact Antenna Pointing Mechanism (APM). The APM was specially designed to meet the stringent mass, envelope, and environmental requirements of OFFEQ experimental satellite. During the development phase, some problems were encountered with the brushless DC motors, slip ring contact resistance, and bearing drag torque. All of these problems were resolved, and two APM units have been operating successfully in orbit since April, 1995.

  1. Design of On-Chip N-Fold Orbital Angular Momentum Multicasting Using V-Shaped Antenna Array

    PubMed Central

    Du, Jing; Wang, Jian

    2015-01-01

    We design a V-shaped antenna array to realize on-chip multicasting from a single Gaussian beam to four orbital angular momentum (OAM) beams. A pattern search assisted iterative (PSI) algorithm is used to design an optimized continuous phase pattern which is further discretized to generate collinearly superimposed multiple OAM beams. Replacing the designed discrete phase pattern with corresponding V-shaped antennas, on-chip N-fold OAM multicasting is achieved. The designed on-chip 4-fold OAM multicasting exploiting V-shaped antenna array shows favorable operation performance with low crosstalk less than -15 dB. PMID:25951325

  2. Mitigating Multipath Bias Using a Dual-Polarization Antenna: Theoretical Performance, Algorithm Design, and Simulation

    PubMed Central

    Xie, Lin; Cui, Xiaowei; Zhao, Sihao; Lu, Mingquan

    2017-01-01

    It is well known that multipath effect remains a dominant error source that affects the positioning accuracy of Global Navigation Satellite System (GNSS) receivers. Significant efforts have been made by researchers and receiver manufacturers to mitigate multipath error in the past decades. Recently, a multipath mitigation technique using dual-polarization antennas has become a research hotspot for it provides another degree of freedom to distinguish the line-of-sight (LOS) signal from the LOS and multipath composite signal without extensively increasing the complexity of the receiver. Numbers of multipath mitigation techniques using dual-polarization antennas have been proposed and all of them report performance improvement over the single-polarization methods. However, due to the unpredictability of multipath, multipath mitigation techniques based on dual-polarization are not always effective while few studies discuss the condition under which the multipath mitigation using a dual-polarization antenna can outperform that using a single-polarization antenna, which is a fundamental question for dual-polarization multipath mitigation (DPMM) and the design of multipath mitigation algorithms. In this paper we analyze the characteristics of the signal received by a dual-polarization antenna and use the maximum likelihood estimation (MLE) to assess the theoretical performance of DPMM in different received signal cases. Based on the assessment we answer this fundamental question and find the dual-polarization antenna’s capability in mitigating short delay multipath—the most challenging one among all types of multipath for the majority of the multipath mitigation techniques. Considering these effective conditions, we propose a dual-polarization sequential iterative maximum likelihood estimation (DP-SIMLE) algorithm for DPMM. The simulation results verify our theory and show superior performance of the proposed DP-SIMLE algorithm over the traditional one using only an

  3. Electromagnetic simulation of helicon plasma antennas for their electrostatic shield design

    SciTech Connect

    Stratakos, Yorgos Zeniou, Angelos Gogolides, Evangelos

    2016-05-15

    A detailed electromagnetic parametric analysis of the helicon antenna (half Nagoya type) is shown at 13.56 MHz using a CST Microwave Studio 2012. The antenna is used to excite plasma inside a dielectric cylinder similar to a commercial reactor. Instead of focusing on the plasma state, the authors focus on the penetration and the three dimensional distribution of electric fields through the dielectric wall. Our aim is to reduce capacitive coupling which produces unwanted longitudinal and radial electric fields. Comparison of the helicon antenna electromagnetic performance under diverse boundary conditions shows that one is allowed to use vacuum simulations without plasma present in the cylinder, or approximate the plasma as a column of gyrotropic material with a tensor dielectric permittivity and with a sheath of a few millimeters in order to qualitatively predict the electric field distribution, thus avoiding a full plasma simulation. This way the analysis of the full problem is much faster and allows an optimal shield design. A detailed study of various shields shows that one can reduce the radial and axial fields by more than 1 order of magnitude compared to the unshielded antenna, while the azimuthal field is reduced only by a factor of 2. Optimal shield design in terms of pitch and spacing of openings is determined. Finally, an experimental proof of concept of the effect of shielding on reduced wall sputtering is provided, by monitoring the roughness created during oxygen plasma etching of an organic polymer.

  4. Operating the Upgraded NSTX HHFW Antenna Array in an Environment with Li-coated Surfaces

    SciTech Connect

    Ryan, Philip Michael; Ellis, R.; Hosea, J.; Kung, C. C.; LeBlanc, B; Pinsker, R.; Taylor, G.; Wilson, J. R.; NSTX Team,

    2011-01-01

    The single-feed, end-grounded straps of the NSTX 12-strap HHFW antenna array have been replaced with double-feed, center-grounded straps to reduce the voltages in the vicinity of the Faraday shield (FS) for a given strap current. The strap spacings to the FS and to the back plate were increased by 3 mm to decrease the electric fields for a given voltage. The electric fields near the FS have been roughly halved for the same strap currents, permitting a direct examination of the roles that internal fields play in determining antenna power limits in plasmas. Extensive RF/plasma conditioning of the antenna was required to remove enough of the evaporated Li deposits from prior wall conditioning to permit coupling in excess of 4 MW to L- and H-mode plasmas in 2009. Most arcs were associated with expulsion of Li from the FS/antenna frame surfaces. The center-grounded straps were less susceptible to arcing during ELMing Hmode plasmas. Reliable operation above 2 MW was difficult after the installation of the Liquid Lithium Divertor (LLD) in 2010. Li-compound dust was found in the antennas after this run and is believed to have contributed to the reduced power limit.

  5. Operating The Upgraded NSTX HHFW Antenna Array In An Environment With Li-coated Surfaces

    SciTech Connect

    Ryan, P. M.; Ellis, R.; Hosea, J. C.; Kung, C. C.; LeBlanc, B. P.; Taylor, G.; Wilson, J. R.; Pinsker, R. I.

    2011-12-23

    The single-feed, end-grounded straps of the NSTX 12-strap HHFW antenna array have been replaced with double-feed, center-grounded straps to reduce the voltages in the vicinity of the Faraday shield (FS) for a given strap current. The strap spacings to the FS and to the back plate were increased by 3 mm to decrease the electric fields for a given voltage. The electric fields near the FS have been roughly halved for the same strap currents, permitting a direct examination of the roles that internal fields play in determining antenna power limits in plasmas. Extensive RF/plasma conditioning of the antenna was required to remove enough of the evaporated Li deposits from prior wall conditioning to permit coupling in excess of 4 MW to L- and H-mode plasmas in 2009. Most arcs were associated with expulsion of Li from the FS/antenna frame surfaces. The center-grounded straps were less susceptible to arcing during ELMing H-mode plasmas. Reliable operation above 2 MW was difficult after the installation of the Liquid Lithium Divertor (LLD) in 2010. Li-compound 'dust' was found in the antennas after this run and is believed to have contributed to the reduced power limit.

  6. Experimental fixation of femoral osteotomies by cerclage with nylon straps.

    PubMed

    Rhinelander, F W; Stewart, C L

    1983-10-01

    Following the successful experience of Partridge in the fixation of human femoral fractures by nylon-strap cerclage, this research in 23 mature dogs was performed to compare nylon-strap with wire-loop cerclage for healing periods of up to 12 weeks. Supplemented by intramedullary fixation with Steinmann pins, long oblique femoral osteotomies were fixed in one femur of each dog by nylon straps and in the other femur by wire loops, at separate operations. The nylon straps were all secured at the same tension by a special "gun." The wire loops were all secured at the same tension by the Rhinelander tightener-twister. Half of the nylon straps had "bumps" along the inner surface, which were added by Partridge in an effort to circumvent the microvascular disturbance reported with Parham bands. On examination by microangiography and correlated histology, all of the osteotomies, regardless of the type of fixation, showed good progress toward osseous union. After fixation by wire cerclage no loss of position or disturbance of blood supply was noted. After fixation by nylon straps slight (clinically insignificant) longitudinal displacement, attributed to slight lengthening of the straps, with consequent loosening was noted in all cases. This loosening was considered advantageous because it appeared to be responsible for the unexpected lack of impairment of the vascularization of the underlying cortical bone by any of the straps. The bumps on the undersurface of some of the straps were, thus, of no vascular advantage, and their presence made accurate fixation of the ostectomy fragments more difficult on the small bones. These studies support the value of fixation by plain nylon straps and show their advantage over straps with bumps for fixation of long oblique single osteotomies of bones the size of the canine femur.

  7. Development of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna Design for NASA

    NASA Technical Reports Server (NTRS)

    Spence, Thomas; Cooley, Michael; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

    2016-01-01

    A dual-band (Ka/W) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of NASA's planned Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflect array with a fixed W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflect array surface. More recently the science community has expressed interest in a mission that offers the ability to measure precipitation (Ku- band with scanning) in addition to clouds and aerosols. In this paper we present findings from a design study that explores options for realizing a tri-frequency (Ku/Ka/W), shared-aperture antenna system to meet these science objectives. Design considerations included meeting performance requirements while striving to minimize payload size, weight, prime power, and cost. The extensive trades and lessons learned from the ACE system development were utilized as the foundation for this work.

  8. Sequential design of a linear quadratic controller for the Deep Space Network antennas

    NASA Technical Reports Server (NTRS)

    Gawronski, W.

    1992-01-01

    A new linear quadratic controller design procedure is proposed for the NASA/JPL Deep Space Network antennas. The antenna model is divided into a tracking subsystem and a flexible subsystem. Controllers for the flexible and tracking parts are designed separately by adjusting the performance index weights. Ad hoc weights are chosen for the tracking part of the controller and the weights of the flexible part are adjusted. Next, the gains of the tracking part are determined, followed by the flexible controller final tune-up. In addition, the controller for the flexible part is designed separately for each mode; thus the design procedure consists of weight adjustment for small-size subsystems. Since the controller gains are obtained by adjusting the performance index weights, determination of the weight effect on system performance is a crucial task. A method of determining this effect that allows an on-line improvement of the tracking performance is presented in this article. The procedure is illustrated with the control system design for the Deep Space Station (DSS)-13 antenna.

  9. Sequential design of a linear quadratic controller for the Deep Space Network antennas

    NASA Technical Reports Server (NTRS)

    Gawronski, W.

    1992-01-01

    A new linear quadratic controller design procedure is proposed for the NASA/JPL Deep Space Network antennas. The antenna model is divided into a tracking subsystem and a flexible subsystem. Controllers for the flexible and tracking parts are designed separately by adjusting the performance index weights. Ad hoc weights are chosen for the tracking part of the controller and the weights of the flexible part are adjusted. Next, the gains of the tracking part are determined, followed by the flexible controller final tune-up. In addition, the controller for the flexible part is designed separately for each mode; thus the design procedure consists of weight adjustment for small-size subsystems. Since the controller gains are obtained by adjusting the performance index weights, determination of the weight effect on system performance is a crucial task. A method of determining this effect that allows an on-line improvement of the tracking performance is presented in this article. The procedure is illustrated with the control system design for the DSS-13 antenna.

  10. Concept Design of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Spence, Thomas; Cooley, Michael E.; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

    2016-01-01

    A scalable dual-band (Ka/W) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of the planned NASA Earth Science Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflectarray with a fixed pointing W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflectarray surface. More recently the science community has expressed interest in a mission that offers the ability to measure precipitation in addition to clouds and aerosols. In this paper we present summaries of multiple designs that explore options for realizing a tri-frequency (Ku/Ka/W), shared-aperture antenna system to meet these science objectives. Design considerations include meeting performance requirements while emphasizing payload size, weight, prime power, and cost. The extensive trades and lessons learned from our previous dual-band ACE system development were utilized as the foundation for this work.

  11. Concept Design of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Spence, Thomas; Cooley, Michael; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

    2016-01-01

    A scalable dual-band (KaW) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of the planned NASA Earth Science Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflectarray with a fixed pointing W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflectarray surface.More recently the science community has expressed interest in a mission that offers the ability to measure precipitation in addition to clouds and aerosols. In this paper we present summaries of multiple designs that explore options for realizing a tri-frequency (KuKaW), shared-aperture antenna system to meet these science objectives. Design considerations include meeting performance requirements while emphasizing payload size, weight, prime power, and cost. The extensive trades and lessons learned from our previous dual-band ACE system development were utilized as the foundation for this work.

  12. A coaxial slot antenna with frequency of 433 MHz for microwave ablation therapies: design, simulation, and experimental research.

    PubMed

    Jiang, Yingxu; Zhao, Jinzhe; Li, Weitao; Yang, Yamin; Liu, Jia; Qian, Zhiyu

    2017-05-02

    Investigation of the structures and properties of antennas is important in the design of microwave ablation (MWA) system. In this study, we studied the performance of the novel tri- and single-slot antennas with frequency of 433 MHz in ex vivo conditions. The dielectric properties of liver tissue under different thermal coagulation levels were explored, which was beneficial to evaluate ablation condition of tissue and simulate temperature field. Then, the performances of the antennas were analyzed by using numerical method based on finite element method (FEM). It indicated that the present antennas with frequency of 433 MHz could produce a gourd-shaped MWA area with a longer length. Compared to antenna with frequency of 2450 MHz, the designed single-slot antenna could obtain the larger MWA area. In addition, the multiple-point ablations and a larger MWA area could be achieved simultaneously by using the present tri-slot antenna. This study has a potential for the innovative design of MWA antenna for treatment of liver tumor with a large range and a long length.

  13. Design and Prototyping of a Satellite Antenna Slew Testbed

    DTIC Science & Technology

    2013-12-01

    manufacturing of 3D parts from CAD geometry. CAD models are imported in the stereo lithography (.STL) file format to the printer software [5]. The .STL...files are created from Solidworks after the part or assembly has been designed and saved as a .STL file. After orienting the part for the build, the...thesis, the design process began with paper drawings and continued into CAD modeling. The CAD program used was Solidworks ® 2012. The author had

  14. A Simple Tool for the Design and Analysis of Multiple-reflector Antennas in a Multi-disciplinary Environment

    NASA Technical Reports Server (NTRS)

    Katz, Daniel, S.; Borgioli, Andrea; Cwik, Tom; Fu, Chuigang; Imbriale, William A.; Jamnejad, Vahraz; Springer, Paul L.

    1999-01-01

    The process of designing and analyzing a multiple-reflector system has traditionally been time-intensive, requiring large amounts of both computational and human time. At many frequencies, a discrete approximation of the radiation integral may be used to model the system. The code which implements this physical optics (PO) algorithm was developed at the Jet Propulsion Laboratory. It analyzes systems of antennas in pairs, and for each pair, the analysis can be computationally time-consuming. Additionally, the antennas must be described using a local coordinate system for each antenna, which makes it difficult to integrate the design into a multi-disciplinary framework in which there is traditionally one global coordinate system, even before considering deforming the antenna as prescribed by external structural and/or thermal factors. Finally, setting up the code to correctly analyze all the antenna pairs in the system can take a fair amount of time, and introduces possible human error.

  15. Experimental evaluation of shape memory alloy actuation technique in adaptive antenna design concepts

    NASA Technical Reports Server (NTRS)

    Kefauver, W. Neill; Carpenter, Bernie F.

    1994-01-01

    Creation of an antenna system that could autonomously adapt contours of reflecting surfaces to compensate for structural loads induced by a variable environment would maximize performance of space-based communication systems. Design of such a system requires the comprehensive development and integration of advanced actuator, sensor, and control technologies. As an initial step in this process, a test has been performed to assess the use of a shape memory alloy as a potential actuation technique. For this test, an existing, offset, cassegrain antenna system was retrofit with a subreflector equipped with shape memory alloy actuators for surface contour control. The impacts that the actuators had on both the subreflector contour and the antenna system patterns were measured. The results of this study indicate the potential for using shape memory alloy actuation techniques to adaptively control antenna performance; both variations in gain and beam steering capabilities were demonstrated. Future development effort is required to evolve this potential into a useful technology for satellite applications.

  16. Experimental evaluation of shape memory alloy actuation technique in adaptive antenna design concepts

    NASA Astrophysics Data System (ADS)

    Kefauver, W. Neill; Carpenter, Bernie F.

    1994-09-01

    Creation of an antenna system that could autonomously adapt contours of reflecting surfaces to compensate for structural loads induced by a variable environment would maximize performance of space-based communication systems. Design of such a system requires the comprehensive development and integration of advanced actuator, sensor, and control technologies. As an initial step in this process, a test has been performed to assess the use of a shape memory alloy as a potential actuation technique. For this test, an existing, offset, cassegrain antenna system was retrofit with a subreflector equipped with shape memory alloy actuators for surface contour control. The impacts that the actuators had on both the subreflector contour and the antenna system patterns were measured. The results of this study indicate the potential for using shape memory alloy actuation techniques to adaptively control antenna performance; both variations in gain and beam steering capabilities were demonstrated. Future development effort is required to evolve this potential into a useful technology for satellite applications.

  17. Design and Development of VHF Antennas for Space Borne Signal of Opportunity Receivers for Cubesat Platforms

    NASA Technical Reports Server (NTRS)

    Deshpande, Manohar; Piepmeier, Jeffrey

    2015-01-01

    Design and Development of VHF Antennas for Space Borne Signal of Opportunity Receivers for Cubesat Platforms. Space borne microwave remote sensors at VHF/UHF frequencies are important instruments to observe reflective properties of land surfaces through thick and heavy forestation on a global scale. One of the most cost effective ways of measuring land reflectivity at VHF/UHF frequencies is to use signals transmitted by existing communication satellites (operating at VHF/UHF band) as a signal of opportunity (SoOp) signal and passive receivers integrated with airborne/space borne platforms operating in the Low Earth Orbit (LEO). One of the critical components of the passive receiver is two antennas (one to receive only direct signal and other to receive only reflected signal) which need to have ideally high (>30dB) isolation. However, because of small size of host platforms and broad beam width of dipole antennas, achieving adequate isolation between two channels is a challenging problem and need to be solved for successful implementation of space borne SoOp technology for remote sensing. In this presentation a novel enabling VHF antenna technology for Cubesat platforms is presented to receive direct as well as reflected signal with needed isolation. The novel scheme also allows enhancing the gain of individual channels by factor of 2 without use of reflecting ground plane

  18. Shaped-beam antenna design considerations for high power broadcasting satellites

    NASA Astrophysics Data System (ADS)

    Toyama, N.

    In order to achieve better service quality than that of the present satellites, a novel technique is described to design a multiple-horn type circularly polarized shaped-beam antenna as a possible candidate for a next generation large scale high power broadcasting satellite. WARC-BS related antenna requirements, such as a spill over power of both copolar and cross-polar components radiated outside the service area, are considered on the basis of power flux density on the earth assuming the antenna input power of 200 W. In order to transmit more satellite power to more densely populated cities, the service area is split into five regions where the shapes of the split regions, each covered by the five antenna beams, are different from each other. A corrugated conical horn with elliptical aperture is used as a main feed horn to illuminate an offset paraboloidal reflector with circular aperture to cover an elliptical main region. In order to make the beam separation distances between the feed horns short, pyramidal horns with crossed rectangular apertures are used which cover the other regions in the service area.

  19. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    NASA Technical Reports Server (NTRS)

    Kunath, Richard R.; Claspy, Paul C.; Richard, Mark A.; Bhasin, Kul B.

    1990-01-01

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  20. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    NASA Astrophysics Data System (ADS)

    Kunath, Richard R.; Claspy, Paul C.; Richard, Mark A.; Bhasin, Kul B.

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  1. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    NASA Astrophysics Data System (ADS)

    Kunath, Richard R.; Bhasin, Kul B.; Claspy, Paul C.; Richard, Mark A.

    1990-06-01

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  2. Nylon sublaminar straps in segmental instrumentation for spinal disorders.

    PubMed

    O'Brien, J P; Stephens, M M; Prickett, C F; Wilcox, A; Evans, J H

    1986-02-01

    A new modification of segmental spinal instrumentation is in an early stage of research and development. Preliminary evidence is most encouraging with respect to the advantages of the relative safety of insertion of the nylon strap around the neural arch. The facility with which the insertion and tightening of the strap can be employed reduces the operation time significantly.

  3. Structural design options for the new 34 meter beam waveguide antenna

    NASA Technical Reports Server (NTRS)

    Katow, S.; Cucchissi, J. J.; Chuang, K. L.; Levy, R.; Lansing, F. L.; Stoller, F. W.; Menninger, F.

    1987-01-01

    In addition to the successful network of 34 m High Efficiency antennas recently built by JPL, the Deep Space Network (DSN) is embarking on the construction of a 34 m high performance, research and development antenna with beam waveguide optics at the Venus site. The construction of this antenna presents many engineering challenges in the area of structural, mechanical, RF, and pointing system design. A set of functional and structural design requirements is outlined to guide analysts in the final configuration selection. Five design concepts are presented covering both the conventional center-fed beam optics as well as the nonconventional, by-pass beam configuration. The merits of each concept are discussed with an emphasis on obtaining a homologous design. The preliminary results of structural optimization efforts, currently in progress, are promising, indicating the feasibility of meeting, as a minimum, all X-band (8.4 GHz) requirements, with a goal towards meeting Ka-band (32 GHz) quality performance, at the present budget constraints.

  4. Recent Progress in Active Antenna Designs for the Long Wavelength Array (LWA)

    NASA Astrophysics Data System (ADS)

    Hicks, B. C.; Stewart, K. P.; Paravastu, N.; Bradley, R. F.; Parashare, C. R.; Erickson, W. C.; Gross, C.; Polisensky, E.; Crane, P. C.; Ray, P. S.; Kassim, N. E.; Weiler, K. W.

    2005-12-01

    We present new designs for active antenna systems optimized for HF/VHF radio astronomy, ionospheric science, space weather, and other radio science applications. Active antenna designs have been developed and tested which satisfy the need for high linearity and stability while achieving Galactic background dominated noise levels. The presence of very strong terrestrial radio-frequency interference (RFI), and world-wide propagation at these frequencies require that the preamplifiers have very high dynamic range. Distortion products must be below the Galactic background level for RFI mitigation techniques to be successful. Individual antennas should have broad response patterns to cover most of the sky without pointing mechanisms, but with decreased sensitivity at low elevations. Ideal designs would also be immune to environmental effects such as temperature variations and precipitation. For projects such as the LWA, where thousands of receptors will be needed, they must also be robust, inexpensive, and easy to manufacture and install. We discuss high-performance designs that are optimized for cost-sensitive applications such as the LWA. Basic research in astronomy is supported by the Office of Naval Research.

  5. A strap-on monitoring system for rail car applications

    SciTech Connect

    Hogan, J.; Rey, D.; Mitchell, J.; Breeding, R.; McKeen, R.G.; Brogan, J.

    1996-12-01

    A joint Sandia National Laboratories, University of New Mexico, and New Mexico Engineering Research Institute project to investigate an architecture implementing real-time monitoring and tracking technologies in the railroad industry is presented. The work examines a strap-on sensor package, designed as a value-added component, integrated into existing industry systems and standards. As applied to freight trains, the sensors` primary purpose is to minimize operating costs by decreasing losses due to theft, and by reducing the number, severity, and a consequence of hazardous materials incidents. Product requirements are based on a cost-benefit analysis of operating losses. Results of a concept validation experiment conducted on a revenue generating train are reported.

  6. Design of broadband antenna elements for a low-frequency radio telescope using Pareto genetic algorithm optimization

    NASA Astrophysics Data System (ADS)

    Kerkhoff, A.; Ling, H.

    2009-12-01

    We apply Pareto genetic algorithm (GA) optimization to the design of antenna elements for use in the Long Wavelength Array (LWA), a large, low-frequency radio telescope currently under development. By manipulating antenna geometry, the Pareto GA simultaneously optimizes the received Galactic background or “sky” noise level and radiation patterns of the antenna over all frequencies. Geometrical constraints are handled explicitly in the GA in order to guarantee the realizability, and to impart control over the monetary cost of the generated designs. The antenna elements considered are broadband planar dipoles arranged horizontally over the ground. It is demonstrated that the Pareto GA approach generates a set of designs, which exhibit a wide range of trade-offs between the two design objectives, and satisfy all constraints. Multiple GA executions are performed to determine how antenna performance trade-offs are affected by different geometrical constraint values, feed impedance values, radiating element shapes and orientations, and ground conditions. Two different planar dipole antenna designs are constructed, and antenna input impedance and sky noise drift scan measurements are performed to validate the results of the GA.

  7. Design tradeoff study for reflector antenna systems for the shuttle imaging microwave system

    NASA Technical Reports Server (NTRS)

    Hansen, R. C.

    1974-01-01

    A general tradeoff is made of the symmetric Cassegrain antenna with regard to the possibility of meeting a 90% beam efficiency. The effects of aperture taper and blockage are calculated using an adjustable sidelobe circular distribution. Numerical integration is used. For the feed spillover calculation, a low sidelobe symmetric feed pattern is used with the equivalent parabola and numerical integration. Reflector cross polarization is calculated using double numerical integration. Reflector back lobes are estimated from radiation pattern envelopes of commercial common carrier dish antennas. The curves allow a range of f/D to be determined for a specified edge taper and blockage diameter ratio, and with a table of Cassegrain parameters, a range of possible designs that meet the 90% beam efficiency is obtained. It is shown that the feed and reflector design and implementation must be carefully done.

  8. Design and analysis of an antenna for wireless energy harvesting in a head-mountable DBS device.

    PubMed

    Hosain, Md Kamal; Kouzani, Abbas Z; Tye, Susannah J; Abulseoud, Osama A; Berk, Michael

    2013-01-01

    This paper presents design and simulation of a circular meander dipole antenna at the industrial, scientific, and medical band of 915 MHz for energy scavenging in a passive head-mountable deep brain stimulation device. The interaction of the proposed antenna with a rat body is modeled and discussed. In the antenna, the radiating layer is meandered, and a FR-4 substrate is used to limit the radius and height of the antenna to 14 mm and 1.60 mm, respectively. The resonance frequency of the designed antenna is 915 MHz and the bandwidth of 15 MHz at a return loss of -10 dB in free space. To model the interaction of the antenna with a rat body, two aspects including functional and biological are considered. The functional aspect includes input impedance, resonance frequency, gain pattern, radiation efficiency of the antenna, and the biological aspect involves electric field distribution, and SAR value. A complete rat model is used in the finite difference time domain based EM simulation software XFdtd. The simulated results demonstrate that the specific absorption rate distributions occur within the skull in the rat model, and their values are higher than the standard regulated values for the antenna receiving power of 1W.

  9. An Aperture-Coupled Patch Antenna Design for Improved Impedance Bandwidth

    DTIC Science & Technology

    2006-11-01

    structure is the frequency variation of the propagation velocity and the presence of higher order waveguide modes that are not incorporated in the... FEKO from EM Software & Systems (www.feko.info) a fully 3-D implementation of the MoM in which the multilayer Greens Function can also be used for a...2.5-D model of semi-infinite substrates. Here we present the calculated and measured antenna characteristics for this new design compared to a

  10. HRMS sky survey wideband feed system design for DSS 24 beam waveguide antenna

    NASA Technical Reports Server (NTRS)

    Stanton, P. H.; Lee, P. R.; Reilly, H. F.

    1993-01-01

    The High-Resolution Microwave Survey (HRMS) Sky Survey project will be implemented on the DSS 24 beam waveguide (BWG) antenna over the frequency range of 2.86 to 10 GHz. Two wideband, ring-loaded, corrugated feed horns were designed to cover this range. The horns match the frequency-dependent gain requirements for the DSS 24 BWG system. The performance of the feed horns and the calculated system performance of DSS 24 are presented.

  11. The optical antenna system design research on earth integrative network laser link in the future

    NASA Astrophysics Data System (ADS)

    Liu, Xianzhu; Fu, Qiang; He, Jingyi

    2014-11-01

    Earth integrated information network can be real-time acquisition, transmission and processing the spatial information with the carrier based on space platforms, such as geostationary satellites or in low-orbit satellites, stratospheric balloons or unmanned and manned aircraft, etc. It is an essential infrastructure for China to constructed earth integrated information network. Earth integrated information network can not only support the highly dynamic and the real-time transmission of broadband down to earth observation, but the reliable transmission of the ultra remote and the large delay up to the deep space exploration, as well as provide services for the significant application of the ocean voyage, emergency rescue, navigation and positioning, air transportation, aerospace measurement or control and other fields.Thus the earth integrated information network can expand the human science, culture and productive activities to the space, ocean and even deep space, so it is the global research focus. The network of the laser communication link is an important component and the mean of communication in the earth integrated information network. Optimize the structure and design the system of the optical antenna is considered one of the difficulty key technologies for the space laser communication link network. Therefore, this paper presents an optical antenna system that it can be used in space laser communication link network.The antenna system was consisted by the plurality mirrors stitched with the rotational paraboloid as a substrate. The optical system structure of the multi-mirror stitched was simulated and emulated by the light tools software. Cassegrain form to be used in a relay optical system. The structural parameters of the relay optical system was optimized and designed by the optical design software of zemax. The results of the optimal design and simulation or emulation indicated that the antenna system had a good optical performance and a certain

  12. Notch Antennas

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.

    2004-01-01

    Notch antennas, also known as the tapered slot antenna (TSA), have been the topics of research for decades. TSA has demonstrated multi-octave bandwidth, moderate gain (7 to 10 dB), and symmetric E- and H- plane beam patterns and can be used for many different applications. This chapter summarizes the research activities on notch antennas over the past decade with emphasis on their most recent advances and applications. This chapter begins with some discussions on the designs of single TSA; then follows with detailed discussions of issues associated with TSA designs and performance characteristics. To conclude the chapter, some recent developments in TSA arrays and their applications are highlighted.

  13. Design of the 0.5 - 1 GHz Planar Recycler Pickup and Kicker Antennas

    SciTech Connect

    Deibele, C.; /Fermilab

    1999-01-01

    The stochastic cooling system in the Recycler ring at Fermilab required the addition of a 0.5-1 GHz cooling system. This requirement dictated the design of a new antenna for this band of the system. The design problem is defined, method of design is illustrated, and the measurement data are reported. The Recycler is a storage ring comprised of mostly permanent magnets located in the tunnel of the Main Injector at Fermilab. The goal for the construction of the Recycler is to collect and store unused antiprotons from collisions in the Tevatron for use in future collisions in the Tevatron. It will both stochastically and electron cool these unused antiprotons before another collision experiment is possible in the Tevatron. By reusing the antiprotons the luminosity of the experiment can be increased faster. The Recycler will use three bands for its stochastic cooling system. It will reuse the existing designs from the Antiproton Source for the 1-2 GHz and 2-4 GHz systems, and it requires a new design for an additional lower frequency band for the 0.5-1 GHz system. Since the existing designs were fabricated using a microstrip topology it was desired that the new design use a similar topology so that the vacuum tank designs and supporting hardware be identical for all three bands. A primary difference between the design of the pickups/kickers of the Antiproton Source and the Recycler is a different aperture in the machine itself. The Recycler has a bigger aperture and consequently reusing the designs for the existing Antiproton Source pickups/kickers is not electrically optimal but is cost efficient. Measurements will be shown later in this paper for the design of the 0.5-1 GHz system showing the effect of the aperture on the antenna performance. A mockup of the Recycler tank was manufactured for designing and testing the 0.5-1 GHz pickups/kickers. The design procedure was an iterative process and required both a constant dialogue and also a strong relationship with a

  14. Proximally placed alignment control strap for ankle varus deformity: a case report.

    PubMed

    Oh-Park, Mooyeon; Park, Geun Young; Hosamane, Sadvi; Kim, Dennis D

    2007-01-01

    Ankle varus is a commonly encountered deformity in patients with neurologic or musculoskeletal disorders. It impedes stability during the stance phase of gait and often causes skin lesions on the lateral ankle area. Plastic or conventional ankle-foot orthoses (AFOs) with supplementary features such as a T-strap or increased contact area of the lateral flange have been used for correctable varus deformities. These supplementary modifications, however, have limitations as effective tools for varus control, and ankle varus may persist despite their use. We are revisiting the concept of a proximally placed alignment control strap for ankle varus, which may overcome the limitations of currently available modifications. This alignment control strap is designed to provide a medially directed force on the tibia and fibula against the force of varus deformation of the ankle. This modification can be easily added to various types of existing AFOs with acceptable aesthetic appearance. We describe 2 cases of manually correctable but persistent varus deformities of the ankle that were successfully controlled by utilization of the proximally placed alignment control strap.

  15. Design and Optimization of a Compact Wideband Hat-Fed Reflector Antenna for Satellite Communications

    NASA Astrophysics Data System (ADS)

    Geterud, Erik G.; Yang, Jian; Ostling, Tomas; Bergmark, Pontus

    2013-01-01

    We present a new design of the hat-fed reflector antenna for satellite communications, where a low reflection coefficient, high gain, low sidelobes and low cross-polar level are required over a wide frequency band. The hat feed has been optimized by using the Genetic Algorithm through a commercial FDTD solver, QuickWave-V2D, together with an own developed optimization code. The Gaussian vertex plate has been applied at the center of the reflector in order to improve the reflection coefficient and reduce the far-out sidelobes. A parabolic reflector with a ring-shaped focus has been designed for obtaining nearly 100% phase efficiency. The antenna's reflection coefficient is below -17 dB and the radiation patterns satisfy the M-x standard co- and cross-polar sidelobe envelopes for satellite ground stations over a bandwidth of 30%. A low-cost monolayer radome has been designed for the antenna with satisfactory performance. The simulations have been verified by measurements; both of them are presented in the paper.

  16. Design of anisotropic focusing metasurface and its application for high-gain lens antenna

    NASA Astrophysics Data System (ADS)

    Guo, Wenlong; Wang, Guangming; Li, Haipeng; Li, Tangjing; Ge, Qichao; Zhuang, Yaqiang

    2017-03-01

    In this paper, we propose an anisotropic focusing metasurface with function of focusing orthogonally polarized waves in refraction and reflection modes respectively. By employing four layered metallic patches spaced by triple layered dielectric spacers, an anisotropic phase element is designed with capability of transmitting x-polarized waves but reflecting y-polarized beams efficiently. Composed of 21 × 21 cells and with size of 105 × 105 mm2, a focusing metasurface operating at 15 GHz is designed with the same focal length of 30 mm for x- and y-polarized waves. By setting a patch antenna at the focal point, the metasurface sample is employed to enhance gain of the radiation source. For verification, the metasurface sample is fabricated and measured. The antenna performance, in terms of realized boresight gain and operating bandwidth under x- and y-polarized waves illumination, is presented. Results show that the 1 dB gain bandwidths are respectively from 14.7 to 15.3 GHz and 14.7 to 15.2 GHz, and the gain are enhanced by 14.1 dB, 15.1 dB in refraction and reflection modes when the metasurface is impinged by x- and y-polarized spherical waves. The proposed anisotropic metasurface may afford an alternative for designing anisotropic planar lens or high-gain antenna.

  17. Design and characterisation of miniaturised cavity-backed patch antenna for microwave hyperthermia.

    PubMed

    Chakaravarthi, Geetha; Arunachalam, Kavitha

    2015-01-01

    The aim of this study was to describe the design and characterisation of a miniaturised 434 MHz patch antenna enclosed in a metal cavity for microwave hyperthermia treatment of cancer. Electromagnetic (EM) field distribution in the near field of a microstrip patch irradiating body tissue was studied using finite element method (FEM) simulations. Antenna miniaturisation was achieved through dielectric loading with very high permittivity, metal enclosure, patch folding and shorting post. Frequency dependent electrical properties of materials were incorporated wherever appropriate using dispersion model and measurements. Antenna return loss and specific absorption rate (SAR) at 434 MHz were measured on muscle phantoms for characterisation. The design was progressively optimised to yield a compact 434 MHz patch (22 mm × 8.8 mm × 10 mm) inside a metal cavity (40 mm × 12 mm) with integrated coupling water bolus (35 mm). The fabricated antenna with integrated water bolus was self resonant at 434 MHz without load, and has better than -10 dB return loss (S11) with 13-20 MHz bandwidth on two different phantoms. SAR at 434 MHz measured using an infrared (IR) thermal camera on split phantoms indicated penetration depth for -3 dB SAR as 8.25 mm compared to 8.87 mm for simulation. The simulated and measured SAR coverage along phantom depth was 3.09 cm(2) and 3.21 cm(2) respectively at -3 dB, and 6.42 cm(2) and 9.07 cm(2) respectively at -6 dB. SAR full width at half maximum (FWHM) at 5 mm and 20 mm depths were 54.68 mm and 51.18 mm respectively in simulation, and 49.47 mm and 43.75 mm respectively in experiments. Performance comparison of the cavity-backed patch indicates more than 89% co-polarisation and higher directivity which resulted in deeper penetration compared to the patch applicators of similar or larger size proposed for hyperthermia treatment of cancer. The fabricated cavity-backed applicator is self-resonant at 434 MHz with a negligible shift in resonance when

  18. Vibration control experiment design for the 15-m hoop/column antenna

    NASA Technical Reports Server (NTRS)

    Ham, F. M.; Hyland, D. C.

    1985-01-01

    A test program is designed for a ground-based vibration control experiment utilizing as the test article the 15-M Hoop/Column Antenna. Overall objectives of the designed ground-based test program include: (1) the validation of large space structure (LSS) control systemm techniques; (2) the validation of LSS parameter identification techniques: (3) the evaluation of actuator of actuator and sensor placement methodology; and (3) the validation of LSS computer models. Critical concerns in LSS Controls and Dynamics are: low frequency vibrational modes, close modal spacing, parameter uncertainties, controller software limitations, nonlinearities and coupling of modes through damping. Analytical results are presented which include compensator designs for varying compensator order.

  19. Scanning beam antenna conceptual design for 20/30 GHz satellite systems

    NASA Technical Reports Server (NTRS)

    Smetana, J.; Sorbello, R.; Crosswell, W. F.

    1983-01-01

    The configuration described is one of four antenna system configurations developed using a variety of monolithic microwave integrated circuit module arrangements and optical systems. A parametric analysis is expected to produce a data base for the selection of design points for a variety of applications. Soon to be accomplished is the design concept of the active (lens) array, which will take into consideration such factors as, coupling effects, the space-fed power divider network design, input bias and control layout, investigation of thermal distribution, and analysis of module failure (graceful degradation).

  20. Computer Aided Design of Microwave Front-End Components and Antennas for Ultrawideband Systems

    NASA Astrophysics Data System (ADS)

    Almalkawi, Mohammad J.

    This dissertation contributes to the development of novel designs, and implementation techniques for microwave front-end components and packaging employing both transmission line theory and classical circuit theory. For compact realization, all the presented components have been implemented using planar microstrip technology. Recently, there has been an increase in the demand for compact microwave front-ends which exhibit advanced functions. Under this trend, the development of multiband front-end components such as antennas with multiple band-notches, dual-band microwave filters, and high-Q reconfigurable filters play a pivotal role for more convenient and compact products. Therefore, the content of this dissertation is composed of three parts. The first part focuses on packaging as an essential process in RF/microwave integration that is used to mitigate unwanted radiations or crosstalk due to the connection traces. In printed circuit board (PCB) interconnects, crosstalk reduction has been achieved by adding a guard trace with/without vias or stitching capacitors that control the coupling between the traces. In this research, a new signal trace configuration to reduce crosstalk without adding additional components or guard traces is introduced. The second part of this dissertation considers the inherent challenges in the design of multiple-band notched ultrawideband antennas that include the integration of multilayer antennas with RF front-ends and the realization of compact size antennas. In this work, a compact UWB antenna with quad band-notched frequency characteristics was designed, fabricated, and tested demonstrating the desired performance. The third part discusses the design of single- and dual-band dual-mode filters exhibiting both symmetric and asymmetric transfer characteristics. In dual-mode filters, the numbers of resonators that determine the order of a filter are reduced by half while maintaining the performance of the actual filter order. Here, in

  1. Array feed/reflector antenna design for intense microwave beams

    NASA Astrophysics Data System (ADS)

    Blank, Stephen J.

    1990-04-01

    It is shown that a planar-array feed has excellent potential as a solution to paraboloidal reflector distortion problems and beam-steering requirements. Numerical results from an algorithmic procedure are presented which show that, for a range of distortion models, appreciable on-axis gain restoration can be achieved with as few as seven elements. For beam-steering to + or - 1 MW, 19 elements are required. For arrays with either seven or 19 elements, high effective aperture elements give higher system gain than elements having lower effective apertures. With 37 elements, excellent gain and beam-steering performance to + or - 1.5 BW is obtained independently of assumed effective aperture of the array element. A few simple rules of thumb are presented for the design of the planar-array feed configuration.

  2. Design considerations for near-field enhancement in optical antennas

    NASA Astrophysics Data System (ADS)

    Fernández-García, Roberto; Sonnefraud, Yannick; Fernández-Domínguez, Antonio I.; Giannini, Vincenzo; Maier, Stefan A.

    2014-01-01

    Nanoantennas for visible and infrared radiation can strongly enhance the interaction of light with matter by their ability to localise electromagnetic fields on nanometric scales. This allows for the engineering of the absorption and radiation capabilities of nanoemitters, such as dye molecules or quantum dots. In this article, we discuss the main parameters influencing the near-field enhancement provided by dimer-type nanoantennas, the configuration most thoroughly studied in the literature. To facilitate the design of structures, we analyse the influence of the substrate, adhesion layers and a reflective metal underlayer, as well as their arrangement in a periodic fashion. We also highlight the factors which increase the damping of the localised plasmonic modes and the spectral differences between far and near-field resonances.

  3. Advancements in artificial magnetic conductor design for improved performance and antenna applications

    NASA Astrophysics Data System (ADS)

    Kern, Douglas John

    for many different design constraints. A unique application of AMC surfaces will be investigated which demonstrates the equivalence between a high impedance AMC structure and a magnetic substrate backed by a PEC ground plane. This structure is called a metamaterial ferrite, or metaferrite for short. This procedure allows for a means of creating an equivalent structure to a magnetic substrate without using any magnetic materials whatsoever. In fact, the metaferrite can be optimized, much like a conventional AMC, to achieve a desired magnetic permeability for one or more frequencies. The uses for such structures are as lightweight, thin absorbers for electromagnetic radiation. Both conventional, high loss absorbers and low loss magnetic materials can be created via the metaferrite equivalence. Further research into metasurfaces resulted in the ability to design a matched impedance metamaterial to act as a magneto-dielectric substrate without using magnetic materials. The metamaterial is optimized by a GA to obtain an equivalent low-loss dielectric and magnetic constant, as a lossy substrate is not beneficial to antenna performance. The primary application of this magneto-dielectric metastructure reduces the aperture size without negatively impacting antenna operating bandwidth. Since no magnetic materials are used in this metastructure, a thin, lightweight, low-profile antenna system could be developed. Finally, the combination of electromagnetic bandgap AMC surfaces and low-profile antennas will be examined to obtain improved antenna performance over the desired frequency band. The result, when optimized correctly, is an antenna system that achieves improved realized gain compared to the conventional antenna. This increase in performance is directly related to the fact that the antenna is placed above an AMC rather than the conventional PEC ground plane, thus improving the antenna gain and pattern shape.

  4. Design and analysis of a large cylinder antenna array in Tianlai

    NASA Astrophysics Data System (ADS)

    Chen, Z. P.; Wang, R. L.; Peterson, J.; Chen, X. L.; Zhang, J. Y.; Shi, H. L.

    2016-07-01

    In order to make a large area survey, detect a large scale structure and understand dark energy, a large radio interference array with a large number of feeds is required. However, cost and deformation control are main considerations in designing a large antenna array. In this paper we designed a cylinder parabolic structure for antenna array 45m x 40m of "Tianlai" project in Xinjiang, China in 2015. In order to largely reduce weight and cost, the antenna was divided into many assemble units, their structure was optimized by MSC.Patran/Nastran and their reflector deformation under various load cases of gravity, snow and wind was analyzed. For the feed support, we compared different types of structure such as arch-bridge, tower, cable and pole, and by mechanical simulations we found that the arch-bridge structure is very helpful to achieve large span, decrease weight and improve stability, for example, the total weight of optimized structure can be reduced to 43.7% of before. Finally some deformation measurement and experiment methods were discussed, which can be extended to array 100m×100m in the future.

  5. Design of UWB monopole antenna with dual notched bands using one modified electromagnetic-bandgap structure.

    PubMed

    Liu, Hao; Xu, Ziqiang

    2013-01-01

    A modified electromagnetic-bandgap (M-EBG) structure and its application to planar monopole ultra-wideband (UWB) antenna are presented. The proposed M-EBG which comprises two strip patch and an edge-located via can perform dual notched bands. By properly designing and placing strip patch near the feedline, the proposed M-EBG not only possesses a simple structure and compact size but also exhibits good band rejection. Moreover, it is easy to tune the dual notched bands by altering the dimensions of the M-EBG. A demonstration antenna with dual band-notched characteristics is designed and fabricated to validate the proposed method. The results show that the proposed antenna can satisfy the requirements of VSWR < 2 over UWB 3.1-10.6 GHz, except for the rejected bands of the world interoperability for microwave access (WiMAX) and the wireless local area network (WLAN) at 3.5 GHz and 5.5 GHz, respectively.

  6. The design of high power, external antennas for radio frequency multicusp ion sources

    NASA Astrophysics Data System (ADS)

    Welton, R. F.; Stockli, M. P.; Roseberry, R. T.; Kang, Y.; Keller, R.

    2004-05-01

    The ion source for the Spallation Neutron Source (SNS) is a radio-frequency, multicusp source designed to deliver H- beam pulses of 45 mA to the SNS accelerator, with a pulse length of 1 ms and a repetition rate of 60 Hz. In order to achieve this performance the source must operate with both high peak rf power, ˜45 kW, and high average rf power, ˜3 kW, over an operational run period of 3 weeks. The most critical source component in this respect is the plasma-immersed, porcelain coated rf antenna which can be susceptible to damage during high power operation. The DESY group has developed an external antenna configuration utilizing an Al2O3 plasma chamber which has demonstrated a very long operational period exceeding 25 000 h. Their source operates with peak rf powers comparable to the SNS source but with greatly reduced average rf powers, ˜50 W. In order to explore the applicability of this external antenna concept to high average power ion sources like the SNS source, we have performed thermal, mechanical, and electromagnetic analyses of the Al2O3 plasma chamber. This article discusses the final design which has resulted from these studies as well as estimates of the power limitations of such devices.

  7. Design of UWB Monopole Antenna with Dual Notched Bands Using One Modified Electromagnetic-Bandgap Structure

    PubMed Central

    Xu, Ziqiang

    2013-01-01

    A modified electromagnetic-bandgap (M-EBG) structure and its application to planar monopole ultra-wideband (UWB) antenna are presented. The proposed M-EBG which comprises two strip patch and an edge-located via can perform dual notched bands. By properly designing and placing strip patch near the feedline, the proposed M-EBG not only possesses a simple structure and compact size but also exhibits good band rejection. Moreover, it is easy to tune the dual notched bands by altering the dimensions of the M-EBG. A demonstration antenna with dual band-notched characteristics is designed and fabricated to validate the proposed method. The results show that the proposed antenna can satisfy the requirements of VSWR < 2 over UWB 3.1–10.6 GHz, except for the rejected bands of the world interoperability for microwave access (WiMAX) and the wireless local area network (WLAN) at 3.5 GHz and 5.5 GHz, respectively. PMID:24170984

  8. Design of high-gain, wideband antenna using microwave hyperbolic metasurface

    SciTech Connect

    Zhao, Yan

    2016-05-15

    In this work, we apply hyperbolic metasurfaces (HMSs) to design high-gain and wideband antennas. It is shown that HMSs formed by a single layer of split-ring resonators (SRRs) can be excited to generate highly directive beams. In particular, we suggest two types of the SRR-HMS: a capacitively loaded SRR (CLSRR)-HMS and a substrate-backed double SRR (DSRR)-HMS. Both configurations ensure that the periodicity of the structures is sufficiently small for satisfying the effective medium theory. For the antenna design, we propose a two-layer-stacked configuration for the 2.4 GHz frequency band based on the DSRR-HMS excited by a folded monopole. Measurement results confirm numerical simulations and demonstrate that an antenna gain of more than 5 dBi can be obtained for the frequency range of 2.1 - 2.6 GHz, with a maximum gain of 7.8 dBi at 2.4 GHz.

  9. Design criteria for limited scan antennas at digital microwave line of sight links

    NASA Astrophysics Data System (ADS)

    Lighthart, L. P.

    1984-10-01

    The angle diversity technique for multipath fading reduction which uses limited scan antennas is examined. Antenna design criteria for this purpose are investigated under the assumption that only group delay requirements instead of fading depth are the determining factors to fulfill bit error ratio (BER) specifications. In a two-way fading model the maximum group delay time difference is in first approximation equal to the ratio between the minimum received signal strength and the path delay time difference. It is known that group delay time differences are dependent on the worst BER and the modulation system. The path delay time difference and the angles of arrival are calculated in a spherical propagation model. To come to a design procedure independent of refractive index profiles it is assumed that each ray is influenced along its path by a constant refractive index gradient. Combining the results from the spherical propagation model and the group delay requirements allows the computation of the maximum fading depth for given angles of arrival. The pattern envelope of limited scan antennas around the angles of interest are derived under the assumption that infinite deep fading occurs if no diversity technique is used.

  10. High Power Antenna Design for Lower Hybrid Current Drive in MST

    NASA Astrophysics Data System (ADS)

    Thomas, M. A.; Goetz, J. A.; Kaufman, M. C.; Oliva, S. P.; Caughman, J. B. O.; Ryan, P. M.

    2003-10-01

    RF current drive has been proposed as a method for reducing the tearing fluctuations that are responsible for anomalous energy transport in the RFP. A system for launching lower hybrid slow waves at 800 MHz and n_||= 7.5 is now in operation at up to 50 kW on MST. The antenna is an enclosed interdigital line using λ/4 resonators with an opening in the cavity through which the wave is coupled to the plasma. It has an untuned VSWR of ˜2, and is instrumented on 5 of its 23 elements to allow measurement of damping length. The antenna design is being optimized for higher power handling. Improvements include larger vacuum feedthroughs, better impedance matching, and RF instrumentation on all resonators. The new antenna will be modeled in Microwave Studio^TM. The goal is a design which can handle ˜250 kW and presents a VSWR of 1.4 or better without external tuning. Full instrumentation will allow more detailed power deposition measurements.

  11. Novel Dual-band Slot Antenna Design for Bluetooth and UWB Applications

    NASA Astrophysics Data System (ADS)

    Huang, Hai-Yan; Shao, Wei; Wang, Bing-Zhong; Ma, Xiao-Liang

    2014-05-01

    A novel technique to introduce an additional low frequency band to compact ultra wideband (UWB) slot antennas is proposed in this paper. To get an additional Bluetooth band, a parasitic strip is mounted on the back side of the slot edge. Because of the interaction of the strip and the slot edge, the Bluetooth band can be obtained while a notch band between the Bluetooth band and UWB band also appears. Two types of feeding, coplanar waveguide and microstrip line, are investigated. The proposed antennas are both fabricated on a low-cost FR4 substrate and have compact size (24 mm × 28 mm × 1 mm). The good agreement between measured and simulated results verifies our design.

  12. Validation of space/ground antenna control algorithms using a computer-aided design tool

    NASA Technical Reports Server (NTRS)

    Gantenbein, Rex E.

    1995-01-01

    The validation of the algorithms for controlling the space-to-ground antenna subsystem for Space Station Alpha is an important step in assuring reliable communications. These algorithms have been developed and tested using a simulation environment based on a computer-aided design tool that can provide a time-based execution framework with variable environmental parameters. Our work this summer has involved the exploration of this environment and the documentation of the procedures used to validate these algorithms. We have installed a variety of tools in a laboratory of the Tracking and Communications division for reproducing the simulation experiments carried out on these algorithms to verify that they do meet their requirements for controlling the antenna systems. In this report, we describe the processes used in these simulations and our work in validating the tests used.

  13. An Improved Gain Wing-Integrated Antenna Design for Meridian UAS and Sensor-Driven Wing Sizing Approach

    NASA Astrophysics Data System (ADS)

    Patil, Ankur Santaji

    Ice sheets in Antarctic and Arctic regions are undergoing rapid changes, causing a rise in sea level with direct impacts on society and the global system. Airborne remote sensing offers a robust way to study changes occurring in this region and the effects on climate. The Center for Remote Sensing of Ice Sheets (CReSIS) has flown many missions in polar regions to collect data on bed topography, basal conditions, and deep internal layers by using high-sensitivity radar and advanced processing algorithms. The goal of the current study is two-fold. First, a new wing-integrated antenna concept is developed for the Meridian, an Unmanned Aerial System (UAS) designed at the University of Kansas. Second, preliminary wing-sizing equations are derived from wing-integrated antenna performance analyses. The purpose of both studies is to improve both current and future UAS sensor-platforms used for remote sensing applications, such as those currently supported by CReSIS. An improved design of a wing-integrated airborne antenna array is presented by performing an antenna trade study for three low-profile antennas. This study seeks to improve not only the gain of the antenna system but the aircraft performance by developing a structurally-embedded design. Three candidate antenna designs are carried forward to the detailed design stage. These designs include a planar dipole embedded in the lower wing skin of the vehicle, a planar dipole offset a quarter-wavelength from the conductive lower wing-skin via a custom support structure, and a quarter-wave patch antenna integrated inside the wing. Considering the existing wing size limitations for antenna array integration into the Meridian wing, two different designs are recommended--the first design strictly optimizing antenna performance for the given wing size limitations and the second design improving both the electrical and vehicle performance over the original design. The planar dipole antenna offset from a ground plane offers

  14. Front-end antenna system design for the ITER low-field-side reflectometer system using GENRAY ray tracing

    NASA Astrophysics Data System (ADS)

    Wang, G.; Doyle, E. J.; Peebles, W. A.

    2016-11-01

    A monostatic antenna array arrangement has been designed for the microwave front-end of the ITER low-field-side reflectometer (LFSR) system. This paper presents details of the antenna coupling coefficient analyses performed using GENRAY, a 3-D ray tracing code, to evaluate the plasma height accommodation capability of such an antenna array design. Utilizing modeled data for the plasma equilibrium and profiles for the ITER baseline and half-field scenarios, a design study was performed for measurement locations varying from the plasma edge to inside the top of the pedestal. A front-end antenna configuration is recommended for the ITER LFSR system based on the results of this coupling analysis.

  15. Compact self-grounded Bow-Tie antenna design for an UWB phased-array hyperthermia applicator.

    PubMed

    Takook, Pegah; Persson, Mikael; Gellermann, Johanna; Trefná, Hana Dobšíček

    2017-01-08

    Using UWB hyperthermia systems has the potential to improve the heat delivery to deep seated tumours. In this paper, we present a novel self-grounded Bow-Tie antenna design which is to serve as the basis element in a phased-array applicator. The UWB operation in the frequency range of 0.43-1 GHz is achieved by immersing the antenna in a water bolus. The radiation characteristics are improved by appropriate shaping the water bolus and by inclusion of dielectric layers on the top of the radiating arms of the antenna. In order to find the most appropriate design, we use a combination of performance indicators representing the most important attributes of the antenna. These are the UWB impedance matching, the transmission capability and the effective field size. The antenna was constructed and experimentally validated on muscle-like phantom. The measured reflection and transmission coefficients as well as radiation characteristics are in excellent agreement with the simulated results. MR image acquisitions with antenna located inside MR bore indicate a negligible distortion of the images by the antenna itself, which indicates MR compatibility.

  16. Antenna engineering handbook /2nd edition/

    NASA Astrophysics Data System (ADS)

    Johnson, R. C.; Jasik, H.

    Essential principles, methods, and data for solving a wide range of problems in antenna design and application are presented. The basic concepts and fundamentals of antennas are reviewed, followed by a discussion of arrays of discrete elements. Then all primary types of antennas currently in use are considered, providing concise descriptions of operating principles, design methods, and performance data. Small antennas, microstrip antennas, frequency-scan antennas, conformal and low-profile arrays, adaptive antennas, and phased arrays are covered. The major applications of antennas and the design methods peculiar to those applications are discussed in detail. The employment of antennas to meet the requirements of today's complex electronic systems is emphasized, including earth station antennas, satellite antennas, seeker antennas, microwave-relay antennas, tracking antennas, radiometer antennas, and ECM and ESM antennas. Finally, significant topics related to antenna engineering, such as transmission lines and waveguides, radomes, microwave propagation, and impedance matching and broadbanding, are addressed.

  17. Design considerations for the beamwaveguide retrofit of a ground antenna station

    NASA Astrophysics Data System (ADS)

    Veruttipong, T.; Withington, J.; Galindo-Israel, V.; Imbriale, W.; Bathker, D.

    1987-02-01

    A primary requirement of the NASA Deep Space Network (DSN) is to provide for optimal reception of very low signal levels. This requirement necessitates optimizing the antenna gain to the total system operating noise level quotient. Low overall system noise levels of 16 to 20 K are achieved by using cryogenically cooled preamplifiers closely coupled with an appropriately balanced antenna gain/spillover design. Additionally, high-power transmitters (up to 400 kW CW) are required for spacecraft emergency command and planetary radar experiments. The frequency bands allocated for deep space telemetry are narrow bands near 2.1 and 2.3 GHz (Ka-band), 7.1 and 8.4 GHz (X-band), and 32 and 34.5 GHz (Ka-band). In addition, planned operations for the Search for Extraterrestrial Intelligence (SETI) program require continuous low-noise receive coverage over the 1 to 10 GHz band. To summarize, DSN antennas must operate efficiently with low receive noise and high-power uplink over the 1 to 35 GHz band.

  18. A comparison of reflector antenna designs for wide-angle scanning

    NASA Technical Reports Server (NTRS)

    Zimmerman, M.; Lee, S. W.; Houshmand, B.; Rahmat-Samii, Y.; Acosta, R.

    1989-01-01

    Conventional reflector antennas are typically designed for up to + or - 20 beamwidths scan. An attempt was made to stretch this scan range to some + or - 300 beamwidths. Six single and dual reflector antennas were compared. It is found that a symmetrical parabolic reflector with f/D = 2 and a single circular waveguide feed has the minimum scan loss (only 0.6 dB at Theta sub 0 = 8 deg, or a 114 beamwidths scan). The scan is achieved by tilting the parabolic reflector by an angle equal to the half-scan angle. The f/D may be shortened if a cluster 7 to 19 elements instead of one element is used for the feed. The cluster excitation is adjusted for each new beam scan direction to compensate for the imperfect field distribution over the reflector aperture. The antenna can be folded into a Cassegrain configuration except that, due to spillover and blockage considerations, the amount of folding achievable is small.

  19. Design considerations for the beamwaveguide retrofit of a ground antenna station

    NASA Technical Reports Server (NTRS)

    Veruttipong, T.; Withington, J.; Galindo-Israel, V.; Imbriale, W.; Bathker, D.

    1987-01-01

    A primary requirement of the NASA Deep Space Network (DSN) is to provide for optimal reception of very low signal levels. This requirement necessitates optimizing the antenna gain to the total system operating noise level quotient. Low overall system noise levels of 16 to 20 K are achieved by using cryogenically cooled preamplifiers closely coupled with an appropriately balanced antenna gain/spillover design. Additionally, high-power transmitters (up to 400 kW CW) are required for spacecraft emergency command and planetary radar experiments. The frequency bands allocated for deep space telemetry are narrow bands near 2.1 and 2.3 GHz (Ka-band), 7.1 and 8.4 GHz (X-band), and 32 and 34.5 GHz (Ka-band). In addition, planned operations for the Search for Extraterrestrial Intelligence (SETI) program require continuous low-noise receive coverage over the 1 to 10 GHz band. To summarize, DSN antennas must operate efficiently with low receive noise and high-power uplink over the 1 to 35 GHz band.

  20. Two-step Structural Design of Mesh Antennas for High Beam Pointing Accuracy

    NASA Astrophysics Data System (ADS)

    Zhang, Shuxin; Du, Jingli; Wang, Wei; Zhang, Xinghua; Zong, Yali

    2017-05-01

    A well-designed reflector surface with high beam pointing accuracy in electromagnetic performance is of practical significance to the space application of cable mesh reflector antennas. As for space requirements, circular polarizations are widely used in spaceborne antennas, which usually lead to a beam shift for offset reflectors and influence the beam pointing accuracy. A two-step structural design procedure is proposed to overcome the beam squint phenomenon for high beam pointing accuracy design of circularly polarized offset cable mesh reflectors. A simple structural optimal design and an integrated structural electromagnetic optimization are combined to alleviate the beam squint effect of circular polarizations. It is implemented by cable pretension design and adjustment to shape the offset cable mesh surface. Besides, in order to increase the efficiency of integrated optimization, an update Broyden-Fletcher-Goldfarb-Shanno (BFGS) Hessian matrix is employed in the optimization iteration with sequential quadratic programming. A circularly polarized offset cable mesh reflector is utilized to show the feasibility and effectiveness of the proposed procedure. A high beam pointing accuracy in order of 0.0001º of electromagnetic performance is achieved.

  1. Computer simulations for rf design of a Spallation Neutron Source external antenna H{sup -} ion source

    SciTech Connect

    Lee, S. W.; Kang, Y. W.; Shin, K.; Welton, R. F.; Goulding, R. H.

    2010-02-15

    Electromagnetic modeling of the multicusp external antenna H{sup -} ion source for the Spallation Neutron Source (SNS) has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as {sigma}. Insulation designs along with material selections such as ferrite and Teflon could be included in the computer simulations to compare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion.

  2. Design of an RF Antenna for a Large0Bore, High Power, Steady State Plasma Processing Chamber for Material Separation

    SciTech Connect

    Rasmussen, D.A.; Freeman, R.L.

    2001-11-07

    The purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC, (Contractor), and Archimedes Technology Group, (Participant) is to evaluate the design of an RF antenna for a large-bore, high power, steady state plasma processing chamber for material separation. Criteria for optimization will be to maximize the power deposition in the plasma while operating at acceptable voltages and currents in the antenna structure. The project objectives are to evaluate the design of an RF antenna for a large-bore, high power, steady state plasma processing chamber for material separation. Criteria for optimization will be to maximize the power deposition in the plasma while operating at acceptable voltages and currents in the antenna structure.

  3. Taming the ICRF Antenna - Plasma Edge Interaction via Novel Field-Aligned ICRF Antenna on Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Wukitch, S. J.; Lin, Y.; Terry, J.; Hubbard, A.; Mumgaard, R. T.; Reinke, M. L.; the Alcator C-Mod Team

    2016-10-01

    Although ICRF is attractive for bulk plasma heating due to favorable wave propagation, ICRF antenna - edge plasma interaction remains a challenge. Recent experiments reveal that RF-induced potentials in the scrape-off layer and antenna impurity source are dependent on the power ratio between the inner and outer current staps, Pcent/Pout. Using a modified field aligned antenna, the transmission line network connected the center two straps at [0,pi] to one transmitter and the outer two straps another transmitter. This experiment was motivated by positive three strap antenna results from ASDEX-U. With -30 dB decoupling, we scanned Pcent/Pout from zero to greater than 1000. A minimum in the RF enhanced potential and local impurity source is observed for Pcent/Pout greater than 1 and less than 4 with a gradual rise in impurity source for Pcent/Pout greater than 4. This minimum correlates where the image currents in the antenna limiters are expected to be smallest. We also tested antenna operation in [0,0,pi,pi] antenna phasing and found excessive local impurity production despite the antenna being field aligned. This antenna phasing excites low k and potentially have higher coupling. Latest results and analysis will be presented Supported by US DOE Award DE-FC02-99ER54512.

  4. Design and Implementation of an Adaptive Space-Time Antenna Array for GPS Receivers

    NASA Astrophysics Data System (ADS)

    Li, Jianxing; Zhang, Ming; Shi, Hongyu; Zheng, Shi; Zhang, Anxue

    2015-03-01

    In this paper, an adaptive space-time antenna array to preserve global positioning system (GPS) signals while at the same time cancelling all interfering signals was designed and implemented. In the design, a new constraint vector and modified least mean square (M-LMS) algorithm were introduced and utilized to compute the real-time weights. An experimental system with a total size of 200 mm×200 mm×50 mm was implemented to verify the design. Design considerations and experimental results were presented and discussed. Experimental results show that high anti-jam capability has been achieved in the presence of wideband interfering signals. Therefore, the proposed design can be well applied for GPS receivers to enhance robustness.

  5. Lock 6 Detail of hinge stone with iron straps ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Lock 6 - Detail of hinge stone with iron straps and carved completion date (1830) located on ground at southeast corner of lock - Savannah & Ogeechee Barge Canal, Between Ogeechee & Savannah Rivers, Savannah, Chatham County, GA

  6. 93. DETAIL SHOWING HAND WROUGHT IRON STRAP CONNECTING INNER COLUMN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    93. DETAIL SHOWING HAND WROUGHT IRON STRAP CONNECTING INNER COLUMN OF DRUM TO ATTIC COLUMN BELOW, FIRST CATWALK LEVEL, NORTHEAST WALL, WITH SCALE - Maryland State House, State Circle, Annapolis, Anne Arundel County, MD

  7. Maturation and Hardening of the Stabilized Radiometer Platforms (STRAPS) Field Campaign Report

    SciTech Connect

    Bucholtz, A.; Bluth, R.; Pfaff, B.

    2016-04-01

    Measurements of solar and infrared irradiance by instruments rigidly mounted to an aircraft have historically been plagued by the introduction of offsets and fluctuations into the data that are solely due to the pitch and roll movements of the aircraft. Two STabilized RAdiometer Platforms (STRAPs) were developed for the U.S. Navy in the early to mid-2000s to address this problem. The development was a collaborative effort between the Naval Research Laboratory (NRL), the Naval Postgraduate School Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS), and the U.S. Department of Energy (DOE) Sandia National Laboratories. The STRAPs were designed and built by L-3 Communications Sonoma EO (formerly the small business Sonoma Design Group).

  8. Design and optimization of an ultra wideband and compact microwave antenna for radiometric monitoring of brain temperature.

    PubMed

    Rodrigues, Dario B; Maccarini, Paolo F; Salahi, Sara; Oliveira, Tiago R; Pereira, Pedro J S; Limao-Vieira, Paulo; Snow, Brent W; Reudink, Doug; Stauffer, Paul R

    2014-07-01

    We present the modeling efforts on antenna design and frequency selection to monitor brain temperature during prolonged surgery using noninvasive microwave radiometry. A tapered log-spiral antenna design is chosen for its wideband characteristics that allow higher power collection from deep brain. Parametric analysis with the software HFSS is used to optimize antenna performance for deep brain temperature sensing. Radiometric antenna efficiency (η) is evaluated in terms of the ratio of power collected from brain to total power received by the antenna. Anatomical information extracted from several adult computed tomography scans is used to establish design parameters for constructing an accurate layered 3-D tissue phantom. This head phantom includes separate brain and scalp regions, with tissue equivalent liquids circulating at independent temperatures on either side of an intact skull. The optimized frequency band is 1.1-1.6 GHz producing an average antenna efficiency of 50.3% from a two turn log-spiral antenna. The entire sensor package is contained in a lightweight and low-profile 2.8 cm diameter by 1.5 cm high assembly that can be held in place over the skin with an electromagnetic interference shielding adhesive patch. The calculated radiometric equivalent brain temperature tracks within 0.4 °C of the measured brain phantom temperature when the brain phantom is lowered 10 °C and then returned to the original temperature (37 °C) over a 4.6-h experiment. The numerical and experimental results demonstrate that the optimized 2.5-cm log-spiral antenna is well suited for the noninvasive radiometric sensing of deep brain temperature.

  9. Design and optimization of an ultra-wideband and compact microwave antenna for radiometric monitoring of brain temperature

    PubMed Central

    Maccarini, Paolo F.; Salahi, Sara; Oliveira, Tiago R.; Pereira, Pedro J. S.; Limão-Vieira, Paulo; Snow, Brent W.; Reudink, Doug; Stauffer, Paul R.

    2014-01-01

    We present the modeling efforts on antenna design and frequency selection to monitor brain temperature during prolonged surgery using non-invasive microwave radiometry. A tapered log-spiral antenna design is chosen for its wideband characteristics that allow higher power collection from deep brain. Parametric analysis with HFSS is used to optimize antenna performance for deep brain temperature sensing. Radiometric antenna efficiency (η) is evaluated in terms of the ratio of power collected from brain to total power received by the antenna. Anatomical information extracted from several adult computed tomography (CT) scans is used to establish design parameters for constructing an accurate layered 3D tissue phantom. This head phantom includes separate brain and scalp regions, with tissue equivalent liquids circulating at independent temperatures on either side of an intact skull. The optimized frequency band is 1.1–1.6 GHz producing an average antenna efficiency of 50.3% from a 2 turn log-spiral antenna. The entire sensor package is contained in a lightweight and low profile 2.8 cm diameter by 1.5 cm high assembly that can be held in place over the skin with an electromagnetic interference (EMI) shielding adhesive patch. The calculated radiometric equivalent brain temperature tracks within 0.4°C of measured brain phantom temperature when the brain phantom is lowered 10°C and then returned to original temperature (37°C) over a 4.6-hour experiment. The numerical and experimental results demonstrate that the optimized 2.5 cm log-spiral antenna is well suited for the non-invasive radiometric sensing of deep brain temperature. PMID:24759979

  10. Design of an 8-40 GHz Antenna for the Wideband Instrument for Snow Measurements (WISM)

    NASA Technical Reports Server (NTRS)

    Durham, Timothy E.; Vanhille, Kenneth J.; Trent, Christopher R.; Lambert, Kevin M.; Miranda, Felix A.

    2015-01-01

    This poster describes the implementation of a 6x6 element, dual linear polarized array with beamformer that operates from about 8-40 GHz. It is implemented using a relatively new multi-layer microfabrication process. The beamformer includes baluns that feed dual-polarized differential antenna elements and reactive splitters that cover the full frequency range of operation. This fixed beam array (FBA) serves as the feed for a multi-band instrument designed to measure snow water equivalent (SWE) from an airborne platform known as the Wideband Instrument for Snow Measurements (WISM).

  11. Study of mechanical architectures of large deployable space antenna apertures: from design to tests

    NASA Astrophysics Data System (ADS)

    Datashvili, L.; Endler, S.; Wei, B.; Baier, H.; Langer, H.; Friemel, M.; Tsignadze, N.; Santiago-Prowald, J.

    2013-12-01

    The technical assessment of large deployable reflector structures covering a diameter range from 4 to 50 m and RF frequencies up to Ka-Band is presented from the conceptual designs to the tests. Parametric FEM analysis tools of the concepts have been developed to study their static, modal and buckling behaviors. According to the selected conceptual design and acquired analysis results two complete breadboards with diameters of 1.6 m and 4 m based on a peripheral ring structure have been designed, manufactured and tested. Test results of both breadboards fulfilling the requirements on deployment repeatability and accuracy as well as scalability demonstrate the successful selection of a deployable ring design and large deployable antenna concept in whole.

  12. Design and analysis of dual U slot reflectarray antenna for X-band applications

    NASA Astrophysics Data System (ADS)

    Ismail, M. Y.; Malik, H. I.; Amin, M.

    2017-05-01

    A novel design of a dual frequency single layer reflectarray antenna is presented for X-band frequency applications. Dual U slots embedded on conventional rectangular microstrip reflectarray have been designed to attain a dual frequency operation. A detailed analysis of the effect on surface current distributions with the introduction of dual U slots is presented. Moreover a parametric study on the variation of significant dimensions of the design have been carried out and analysed thoroughly using a commercially available CST computer model. Proposed design configurations were fabricated above a 0.508 mm thick substrate of Rogers Duroid 5880. The dual U slot configuration offers a significant dual frequency behavior at 8.54 and 11.56 GHz with 10% bandwidth improvement of 47 and 56 MHz with a reflection loss of -4.54 and 4.11 dB respectively.

  13. HotSwap for bioinformatics: a STRAP tutorial.

    PubMed

    Gille, Christoph; Robinson, Peter N

    2006-02-09

    Bioinformatics applications are now routinely used to analyze large amounts of data. Application development often requires many cycles of optimization, compiling, and testing. Repeatedly loading large datasets can significantly slow down the development process. We have incorporated HotSwap functionality into the protein workbench STRAP, allowing developers to create plugins using the Java HotSwap technique. Users can load multiple protein sequences or structures into the main STRAP user interface, and simultaneously develop plugins using an editor of their choice such as Emacs. Saving changes to the Java file causes STRAP to recompile the plugin and automatically update its user interface without requiring recompilation of STRAP or reloading of protein data. This article presents a tutorial on how to develop HotSwap plugins. STRAP is available at http://strapjava.de and http://www.charite.de/bioinf/strap. HotSwap is a useful and time-saving technique for bioinformatics developers. HotSwap can be used to efficiently develop bioinformatics applications that require loading large amounts of data into memory.

  14. Energy harvesting from a backpack instrumented with piezoelectric shoulder straps

    NASA Astrophysics Data System (ADS)

    Granstrom, Jonathan; Feenstra, Joel; Sodano, Henry A.; Farinholt, Kevin

    2007-10-01

    Over the past few decades the use of portable and wearable electronics has grown steadily. These devices are becoming increasingly more powerful. However, the gains that have been made in the device performance have resulted in the need for significantly higher power to operate the electronics. This issue has been further complicated due to the stagnant growth of battery technology over the past decade. In order to increase the life of these electronics, researchers have begun investigating methods of generating energy from ambient sources such that the life of the electronics can be prolonged. Recent developments in the field have led to the design of a number of mechanisms that can be used to generate electrical energy, from a variety of sources including thermal, solar, strain, inertia, etc. Many of these energy sources are available for use with humans, but their use must be carefully considered such that parasitic effects that could disrupt the user's gait or endurance are avoided. These issues have arisen from previous attempts to integrate power harvesting mechanisms into a shoe such that the energy released during a heal strike could be harvested. This study develops a novel energy harvesting backpack that can generate electrical energy from the differential forces between the wearer and the pack. The goal of this system is to make the energy harvesting device transparent to the wearer such that his or her endurance and dexterity is not compromised. This will be accomplished by replacing the traditional strap of the backpack with one made of the piezoelectric polymer polyvinylidene fluoride (PVDF). Piezoelectric materials have a structure such that an applied electrical potential results in a mechanical strain. Conversely, an applied stress results in the generation of an electrical charge, which makes the material useful for power harvesting applications. PVDF is highly flexible and has a high strength, allowing it to effectively act as the load bearing

  15. Development of a 14-vane, double-strapped, 5.8-GHz magnetron oscillator

    NASA Astrophysics Data System (ADS)

    Choi, Jin Joo; Lee, Han Seoul; Jang, Kwang Ho; Sim, Sung Hun; Choi, Heung Sik

    2016-08-01

    Experiments on a 14-vane, double-strapped magnetron oscillator were performed to demonstrate high-power, high-efficiency coherent radiation at 5.8 GHz. The double-strapped magnetron was designed by using the Buneman-Hatree resonance condition, electromagnetic simulations and non-linear three-dimensional particle-in-cell (PIC) simulations. Experiments showed an oscillation output power of 5.3 kW at 5.79 GHz, corresponding to a DC-RF conversion efficiency of 57%. The cathode voltage was 9.2 kV, the collected anode current was 1 A, and the external magnetic field is 7.5 kG. Experimental results for the RF power, oscillation frequency, and efficiency were in good agreement with the corresponding values from non-linear three-dimensional PIC simulations.

  16. Architectural design of a ground-based deep-space optical reception antenna

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1989-01-01

    An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

  17. Architectural design of a ground-based deep-space optical reception antenna

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1989-01-01

    An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

  18. Preliminary Design of the Alfvén Antennas on the J-TEXT Tokamak

    NASA Astrophysics Data System (ADS)

    He, Jiyang; Hu, Qiming; Rao, Bo; Liu, Linzi; Zhuang, Ge; J-TEXT Team

    2015-11-01

    Research on Alfvén waves and Alfvén eigenmodes(AEs) is of importance in tokamak plasma physics, such as investigation of interaction between energetic particles and AEs, turbulence and anomalous transport due to AEs, and so on. In order to study the Alfvén eigenmode excitation, damping features and the interaction between AEs and plasma transport, an Alfvén antennas system is designed for the J-TEXT tokamak. The system can generate high frequency magnetic field aiming to excite the AEs, especially toroidal Alfvén eigenmodes (TAE). For a typical J-TEXT plasma (BT = 1-2.2 T,ne = 3-6 ×1019m-3), the computed gaps in the Alfvén continua range from 300 to 500 kHz, with respect to the Alfvén waves dispersion relation. Three pairs of antennas are designed at different toroidal angles respectively on the low field side. Each pair consisting of two coils installed with angles of +/- 45° off the mid-plane along the poloidal direction. With this system, magnetic field components of mode number m =1-10, n =1-20 can be produced. The calculations show that the magnetic field in the LCFS can reach ~ 10Gs totally while about ~ 0.5Gs for each mode number, with the coil current of 20A. Corresponding author

  19. Printed Wide-Slot Antenna Design with Bandwidth and Gain Enhancement on Low-Cost Substrate

    PubMed Central

    Samsuzzaman, M.; Islam, M. T.; Mandeep, J. S.; Misran, N.

    2014-01-01

    This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS. PMID:24696661

  20. Printed wide-slot antenna design with bandwidth and gain enhancement on low-cost substrate.

    PubMed

    Samsuzzaman, M; Islam, M T; Mandeep, J S; Misran, N

    2014-01-01

    This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS.

  1. On the cross-polarization characteristics of crooked wire antennas designed by genetic-algorithms

    NASA Technical Reports Server (NTRS)

    Rengarajan, S. R.; Rahmat-Samii, Y.

    2002-01-01

    In many modern communication applications there is a need for simple circularly polarized antennas for hemispherical coverage with good axial ratio or low value of cross polarization. We revisited the crooked wire antenna because of its simplicity. This paper presents results of our investigation on the crooked wire antennas and other elements.

  2. Design and characterization of an Antenna Pointing Mechanism for on-orbit servicing missions

    NASA Astrophysics Data System (ADS)

    Purschke, R.; Hoehn, A.

    The goal of this work was to (1) define parameters to characterize a pointing mechanism, (2) design a setup to test these parameters and, (3) verify the test methods by comparing the results to the theoretically calculated or independently verified numbers. The verification of the test results was conducted with an in-house built Antenna Pointing Mechanism for on-orbit servicing applications. The test setup was developed to find a method to measure the behavior of a pointing mechanism. This was realized by mounting a Laser pointer on the antenna interface of the mechanism and pointing it towards a two-dimensional Position Sensitive Detector, providing means to resolve small motions, and to derive velocity and acceleration of the mechanism. The results show good correlation for characteristic parameters such as pointing velocity and acceleration, repeatability, resolution and pointing accuracy of the mechanism. In future work this test method will be qualified for and used to compare the performance of the mechanism at different environmental conditions such as vacuum, temperature and microgravity.

  3. Accurate design of ICRF antennas for RF plasma thruster acceleration units with TOPICA

    SciTech Connect

    Lancellotti, V.; Maggiora, R.; Vecchi, G.; Milanesio, D.; Meneghini, O.

    2007-09-28

    In recent years electromagnetic (RF) plasma generation and acceleration concepts for plasma-based propulsion systems have received growing interest, inasmuch as they can yield continuous thrust as well as highly controllable and wide-ranging exhaust velocities. The acceleration units mostly adopt the Ion Cyclotron Resonance Frequency (ICRF) - a proven technology in fusion experiments for transferring large RF powers into magnetized plasmas, and also used by the VASIMR propulsion system. In this work we propose and demonstrate the use of TOPICA code to design and optimize the ICRF antenna of a typical acceleration stage. To this end, TOPICA was extended to cope with magnetized cylindricaily-symmetric radially-inhomogeneous warm plasmas, which required coding a new module charged with solving Maxwell's equations within the plasma to obtain the relevant Green's function Y-tilde(m,k{sub z}) in the Fourier domain, i.e. the relation between the transverse magnetic and electric fields at the air-plasma interface. Then, calculating the antenna input impedance - and hence the loading - relies on an integral-equation formulation and subsequent finite-element weighted-residual solution scheme for the self-consistent evaluation of the current density distribution on the conducting bodies and at the air-plasma interface.

  4. Accurate design of ICRF antennas for RF plasma thruster acceleration units with TOPICA

    NASA Astrophysics Data System (ADS)

    Lancellotti, V.; Maggiora, R.; Vecchi, G.; Milanesio, D.; Meneghini, O.

    2007-09-01

    In recent years electromagnetic (RF) plasma generation and acceleration concepts for plasma-based propulsion systems have received growing interest, inasmuch as they can yield continuous thrust as well as highly controllable and wide-ranging exhaust velocities. The acceleration units mostly adopt the Ion Cyclotron Resonance Frequency (ICRF)—a proven technology in fusion experiments for transferring large RF powers into magnetized plasmas, and also used by the VASIMR propulsion system. In this work we propose and demonstrate the use of TOPICA code to design and optimize the ICRF antenna of a typical acceleration stage. To this end, TOPICA was extended to cope with magnetized cylindricaily-symmetric radially-inhomogeneous warm plasmas, which required coding a new module charged with solving Maxwell's equations within the plasma to obtain the relevant Green's function Ỹ(m,kz) in the Fourier domain, i.e. the relation between the transverse magnetic and electric fields at the air-plasma interface. Then, calculating the antenna input impedance—and hence the loading—relies on an integral-equation formulation and subsequent finite-element weighted-residual solution scheme for the self-consistent evaluation of the current density distribution on the conducting bodies and at the air-plasma interface.

  5. HotSwap for bioinformatics: A STRAP tutorial

    PubMed Central

    Gille, Christoph; Robinson, Peter N

    2006-01-01

    Background Bioinformatics applications are now routinely used to analyze large amounts of data. Application development often requires many cycles of optimization, compiling, and testing. Repeatedly loading large datasets can significantly slow down the development process. We have incorporated HotSwap functionality into the protein workbench STRAP, allowing developers to create plugins using the Java HotSwap technique. Results Users can load multiple protein sequences or structures into the main STRAP user interface, and simultaneously develop plugins using an editor of their choice such as Emacs. Saving changes to the Java file causes STRAP to recompile the plugin and automatically update its user interface without requiring recompilation of STRAP or reloading of protein data. This article presents a tutorial on how to develop HotSwap plugins. STRAP is available at and . Conclusion HotSwap is a useful and time-saving technique for bioinformatics developers. HotSwap can be used to efficiently develop bioinformatics applications that require loading large amounts of data into memory. PMID:16469097

  6. Design of a radar system based on compact cavity-backed ultra wide band slot antennas for ground penetrating applications

    NASA Astrophysics Data System (ADS)

    Sagnard, F.

    2012-04-01

    Antennas with broadband characteristics have recently found various applications in modern ultra wide band (UWB) communication systems and in ground penetrating radar (GPR). Our applications are focused on imaging the subsurface of a large range of civil engineering structures at several depths using a bistatic GPR positioned on or close to the ground surface. The development of a compact (34*29 cm2) broadband pair of antennas operating in the frequency band from 0.27 to 3.1 GHz, whose radiation characteristics have been preliminary studied theoretically in details in different configurations, is to allow the probing of the subsurface in several frequency sub-bands using a step frequency (SF-GPR) acquisition mode. Microstrip patch antennas (MPAs) are one of the most basic and important types of planar antennas because they offer many advantages such as compact size, low-cost, ease of fabrication, light weight, and various shapes design. However, a low bandwidth and a low gain are the main shortcomings for such planar structure. The microstrip antenna has now reached maturity and many techniques have been suggested for achieving a high bandwidth such as using more complex shapes, parasitic elements, multilayer configurations and the tuning of the feed line. In this paper, an original printed rectangular slot antenna fed by a 50 Ohms CPW (coplanar waveguide) transmission line tuned by a E-shaped patch is presented. Presently, little work has been made to lower the operating frequency band of microstrip antennas at frequencies less than 0.8 MHz and to reduce the antenna size at these frequencies because major applications concern UWB wireless communications. By choosing a relative combination of a E-shaped patch, a linear feed line and a rectangular slot, we have designed an antenna structure on a FR4 substrate (h=1.5mm) with a very wide operating bandwidth whose nearly half of the spectrum covers frequencies lower than 1 GHz. A partial shield, only opened towards the

  7. Optical antenna gain. I - Transmitting antennas

    NASA Technical Reports Server (NTRS)

    Klein, B. J.; Degnan, J. J.

    1974-01-01

    The gain of centrally obscured optical transmitting antennas is analyzed in detail. The calculations, resulting in near- and far-field antenna gain patterns, assume a circular antenna illuminated by a laser operating in the TEM-00 mode. A simple polynomial equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn that display the losses in antenna gain due to pointing errors and the cone angle of the beam in the far field as a function of antenna aperture size and its central obscuration. The results are presented in a series of graphs that allow the rapid and accurate evaluation of the antenna gain which may then be substituted into the conventional range equation.

  8. Optical antenna gain. 1: transmitting antennas.

    PubMed

    Klein, B J; Degnan, J J

    1974-09-01

    The gain of centrally obscured optical transmitting antennas is analyzed in detail. The calculations, resulting in near- and far-field antenna gain patterns, assume a circular antenna illuminated by a laser operating in the TEM(00) mode. A simple polynomial equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn that display the losses in antenna gain due to pointing errors and the cone angle of the beam in the far field as a function of antenna aperture size and its central obscuration. The results are presented in a series of graphs that allow the rapid and accurate evaluation of the antenna gain which may then be substituted into the conventional range equation.

  9. Design and Realization of a Planar Ultrawideband Antenna with Notch Band at 3.5 GHz

    PubMed Central

    2014-01-01

    A small antenna with single notch band at 3.5 GHz is designed for ultrawideband (UWB) communication applications. The fabricated antenna comprises a radiating monopole element and a perfectly conducting ground plane with a wide slot. To achieve a notch band at 3.5 GHz, a parasitic element has been inserted in the same plane of the substrate along with the radiating patch. Experimental results shows that, by properly adjusting the position of the parasitic element, the designed antenna can achieve an ultrawide operating band of 3.04 to 11 GHz with a notched band operating at 3.31–3.84 GHz. Moreover, the proposed antenna achieved a good gain except at the notched band and exhibits symmetric radiation patterns throughout the operating band. The prototype of the proposed antenna possesses a very compact size and uses simple structures to attain the stop band characteristic with an aim to lessen the interference between UWB and worldwide interoperability for microwave access (WiMAX) band. PMID:25133245

  10. A Simple Tool for the Design and Analysis of Multiple-Reflector Antennas in a Multi-Disciplinary Environment

    NASA Technical Reports Server (NTRS)

    Katz, Daniel S.; Cwik, Tom; Fu, Chuigang; Imbriale, William A.; Jamnejad, Vahraz; Springer, Paul L.; Borgioli, Andrea

    2000-01-01

    The process of designing and analyzing a multiple-reflector system has traditionally been time-intensive, requiring large amounts of both computational and human time. At many frequencies, a discrete approximation of the radiation integral may be used to model the system. The code which implements this physical optics (PO) algorithm was developed at the Jet Propulsion Laboratory. It analyzes systems of antennas in pairs, and for each pair, the analysis can be computationally time-consuming. Additionally, the antennas must be described using a local coordinate system for each antenna, which makes it difficult to integrate the design into a multi-disciplinary framework in which there is traditionally one global coordinate system, even before considering deforming the antenna as prescribed by external structural and/or thermal factors. Finally, setting up the code to correctly analyze all the antenna pairs in the system can take a fair amount of time, and introduces possible human error. The use of parallel computing to reduce the computational time required for the analysis of a given pair of antennas has been previously discussed. This paper focuses on the other problems mentioned above. It will present a methodology and examples of use of an automated tool that performs the analysis of a complete multiple-reflector system in an integrated multi-disciplinary environment (including CAD modeling, and structural and thermal analysis) at the click of a button. This tool, named MOD Tool (Millimeter-wave Optics Design Tool), has been designed and implemented as a distributed tool, with a client that runs almost identically on Unix, Mac, and Windows platforms, and a server that runs primarily on a Unix workstation and can interact with parallel supercomputers with simple instruction from the user interacting with the client.

  11. Joint Time/Frequency Analysis and Design of Spiral Antennas and Arrays for Ultra-Wideband Applications

    NASA Astrophysics Data System (ADS)

    Elmansouri, Mohamed Ali

    Ultra-wideband (UWB) systems transmit and receive extremely short pulses, permitting the corresponding antennas to distort their shape. Thus the design of an antenna for a UWB system plays an important role for the reliability and quality of communication. A UWB antenna design coalesces both the determination of conventional frequency domain parameters and the analysis of time domain response into a single overarching system requirement. While the former is needed to ensure system's sensitivity, the later is critical to minimize pulse distortion. Well-designed spiral antennas are known for their almost frequency independent characteristics; thus they are viable candidates for UWB systems from the frequency-domain side. However, due to their fundamental principles of operation, they are dispersive and arguments were made they should not be used for pulsed UWB applications (time-domain side). The presented research unequivocally proves that spiral antennas and various derivatives thereof, including arrays, can be excellent candidates for multi-functional time/frequency domain systems. A complete framework for joint frequency and time domain characterization of planar spiral antennas in UWB communication systems is developed first. By utilizing theory, simulations, and experiments, all essential to the analysis frameworks, the various hypotheses are comprehensively treated and relevant conclusions are established. The dispersion and pulse distortion of the conventional spiral antennas are characterized in the radiation and system modes and conclusions regarding the effects of geometrical parameters such as number of arms, mode of operations, etc., on time- and frequency-domain performance are derived for the first time. A method based on controlling the spiral's growth rate and input pulse shape is demonstrated as an effective approach to reduce the pulse distortion. Theoretical pre-distortion compensation method based on a frequency-dependent delay removal technique

  12. Theory and Practice in ICRF Antennas for Long Pulse Operation

    SciTech Connect

    Colas, L.; Bremond, S.; Mitteau, R.; Chantant, M.; Goniche, M.; Basiuk, V.; Bosia, G.; Gunn, J.P.

    2005-09-26

    Long plasma discharges on the Tore Supra (TS) tokamak were extended in 2004 towards higher powers and plasma densities by combined Lower Hybrid (LH) and Ion Cyclotron Range of Frequencies (ICRF) waves. RF pulses of 20sx8MW and 60sx4MW were produced. TS is equipped with 3 ICRF antennas, whose front faces are ready for CW operation. This paper reports on their behaviour over high power long pulses, as observed with infrared (IR) thermography and calorimetric measurements. Edge parasitic losses, although modest, are concentrated on a small surface and can raise surface temperatures close to operational limits. A complex hot spot pattern was revealed with at least 3 physical processes involved : convected power, electron acceleration in the LH near field, and a RF-specific phenomenon compatible with RF sheaths. LH coupling was also perturbed in the antenna shadow. This was attributed to RF-induced DC ExB0 convection. This motivated sheath modelling in two directions. First, the 2D topology of RF potentials was investigated in relation with the RF current distribution over the antenna, via a Green's function formalism and full-wave calculation using the ICANT code. In front of phased arrays of straps, convective cells were interpreted using the RF current profiles of strip line theory. Another class of convective cells, specific to antenna box corners, was evidenced for the first time. Within 1D sheath models assuming independent flux tubes, RF and rectified DC potentials are proportional. 2D fluid models couple nearby flux tubes via transverse polarisation currents. Unexpectedly this does not necessarily smooth RF potential maps. Peak DC potentials can even be enhanced. The experience gained on TS and the numerical tools are valuable for designing steady state high power antennas for next step devices. General rules to reduce RF potentials as well as concrete design options are discussed.

  13. Design of an 8-40 GHz Antenna for the Wideband Instrument for Snow Measurements (WISM)

    NASA Technical Reports Server (NTRS)

    Durham, Timothy E.; Vanhille, Kenneth J.; Trent, Christopher; Lambert, Kevin M.; Miranda, Felix A.

    2015-01-01

    Measurement of land surface snow remains a significant challenge in the remote sensing arena. Developing the tools needed to remotely measure Snow Water Equivalent (SWE) is an important priority. The Wideband Instrument for Snow Measurements (WISM) is being developed to address this need. WISM is an airborne instrument comprised of a dual-frequency (X- and Ku-bands) Synthetic Aperture Radar (SAR) and dual-frequency (K- and Ka-bands) radiometer. A unique feature of this instrument is that all measurement bands share a common antenna aperture consisting of an array feed reflector that covers the entire bandwidth. This paper covers the design and fabrication of the wideband array feed which is based on tightly coupled dipole arrays. Implementation using a relatively new multi-layer microfabrication process results in a small, 6x6 element, dual-linear polarized array with beamformer that operates from 8 to 40 gigahertz.

  14. Preliminary Optimal Orbit Design for the Laser Interferometer Space Antenna (LISA)

    NASA Technical Reports Server (NTRS)

    Hughes, Steven P.; Bauer, Frank H. (Technical Monitor)

    2002-01-01

    In this paper we present a preliminary optimal orbit analysis for the Laser Interferometer Space Antenna (LISA). LISA is a NASA/ESA mission to study gravitational waves and test predictions of general relativity. The nominal formation consists of three spacecraft in heliocentric orbits at 1 AU and trailing the Earth by twenty degrees. This configuration was chosen as a trade off to reduce the noise sources that will affect the instrument and to reduce the fuel to achieve the final orbit. We present equations for the nominal orbit design and discuss several different measures of performance for the LISA formation. All of the measures directly relate the formation dynamics to science performance. Also, constraints on the formation dynamics due to spacecraft and instrument limitations are discussed. Using the nominal solution as an initial guess, the formation is optimized using Sequential Quadratic Programming to maximize the performance while satisfying a set of nonlinear constraints. Results are presented for each of the performance measures.

  15. Reconfigurable phased antenna array for extending cubesat operations to Ka-band: Design and feasibility

    NASA Astrophysics Data System (ADS)

    Buttazzoni, G.; Comisso, M.; Cuttin, A.; Fragiacomo, M.; Vescovo, R.; Vincenti Gatti, R.

    2017-08-01

    Started as educational tools, CubeSats have immediately encountered the favor of the scientific community, subsequently becoming viable platforms for research and commercial applications. To ensure competitive data rates, some pioneers have started to explore the usage of the Ka-band beside the conventional amateur radio frequencies. In this context, this study proposes a phased antenna array design for Ka-band downlink operations consisting of 8×8 circularly polarized subarrays of microstrip patches filling one face of a single CubeSat unit. The conceived structure is developed to support 1.5 GHz bandwidth and dual-task missions, whose feasibility is verified by proper link budgets. The dual-task operations are enabled by a low-complexity phase-only control algorithm that provides pattern reconfigurability in order to satisfy both orbiting and intersatellite missions, while remaining adherent to the cost-effective CubeSat paradigm.

  16. Controller design and parameter identifiability studies for a large space antenna

    NASA Technical Reports Server (NTRS)

    Joshi, S. M.

    1985-01-01

    The problem of control systems synthesis and parameter identifiability are considered for a large, space-based antenna. Two methods are considered for control system synthesis, the first of which uses torque actuators and collocated attitude and rate sensors, and the second method is based on the linear-quadratic-Gaussian (LQG) control theory. The predicted performance obtained by computing variances of pointing, surface and feed misalignment errors in the presence of sensor noise indicates that the LQG-based controller yields superior results. Since controller design requires the knowledge of the system parameters, the identifiability of the structural parameters is investigated by obtaining Cramer-Rao lower bounds. The modal frequencies are found to have the best identifiability, followed by damping ratios, and mode-slopes.

  17. Design and analysis of a deployable truss for the large modular mesh antenna

    NASA Astrophysics Data System (ADS)

    Meguro, Akira

    This paper describes the design and deployment analysis for large deployable modular mesh antennas. Key design criteria are deployability, and the driving force and latching moment requirements. Reaction forces and moments due to mesh and cable network seriously influence the driving force. These forces and moments can be precisely estimated by means of analyzing the cable network using Cable Structure Analyzer (CASA). Deployment analysis is carried out using Dynamic Analysis and Design System (DADS). The influence of alignment errors on the driving reaction force can be eliminated by replacing the joint element with a spring element. The joint slop is also modeled using a discontinuous spring elements. Their design approach for three types of deployable modules and the deployment characterstics of three Bread-Board Models based on those designs are also presented. In order to study gravity effects on the deployment characteristics and the effects of the gravity compensation method, ground deployment analysis is carried out. A planned deployment test that will use aircraft parabolic flight to simulate a micro-gravity environment is also described.

  18. Plastic debris straps on threatened blue shark Prionace glauca.

    PubMed

    Colmenero, Ana I; Barría, Claudio; Broglio, Elisabetta; García-Barcelona, Salvador

    2017-02-15

    Juveniles of blue shark Prionace glauca caught in pelagic longlines targeting tuna and swordfish in the Atlantic Ocean and the Mediterranean Sea were found entangled with plastic straps around their gill region. The plastic debris were identified as strapping bands and caused several degrees of injuries on the dorsal musculature and pectoral fins. They were also obstructing the gill slits probably causing breathing issues. These records were uploaded in the web site seawatchers.org, and highlight the potential of citizen science in revealing the occurrence of such problems which could help to measure the effects of plastic debris on marine life. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Strain powered antennas

    NASA Astrophysics Data System (ADS)

    Domann, John P.; Carman, Greg P.

    2017-01-01

    This paper proposes the creation of strain powered antennas that radiate electromagnetic energy by mechanically vibrating a piezoelectric or piezomagnetic material. A closed form analytic model of electromagnetic radiation from a strain powered electrically small antenna is derived and analyzed. Fundamental scaling laws and the frequency dependence of strain powered antennas are discussed. The radiation efficiency of strain powered electrically small antennas is contrasted with a conventional electric dipole. Analytical results show that operating at the first mechanical resonance produces the most efficient strain powered radiation relative to electric dipole antennas. A resonant analysis is exploited to determine the material property space that produces efficient strain powered antennas. These results show how a properly designed strain powered antenna can radiate more efficiently than an equally sized electric dipole antenna.

  20. The design of an ultra-thin and multiple channels optical receiving antenna system with freeform lenses

    NASA Astrophysics Data System (ADS)

    Zhang, Lingyun; Cheng, Dewen; Hu, Yuan; Song, Weitao; Wang, Yongtian

    2014-11-01

    Visible Light Communications (VLC) has become an emerging area of research since it can provide higher data transmission speed and wider bandwidth. The white LEDs are very important components of the VLC system, because it has the advantages of higher brightness, lower power consumption, and a longer lifetime. More importantly, their intensity and color are modulatable. Besides the light source, the optical antenna system also plays a very important role in the VLC system since it determines the optical gain, effective working area and transmission rate of the VLC system. In this paper, we propose to design an ultra-thin and multiple channels optical antenna system by tiling multiple off-axis lenses, each of which consists of two reflective and two refractive freeform surfaces. The tiling of multiple systems and detectors but with different band filters makes it possible to design a wavelength division multiplexing VLC system to highly improve the system capacity. The field of view of the designed antenna system is 30°, the entrance pupil diameter is 1.5mm, and the thickness of the system is under 4mm. The design methods are presented and the results are discussed in the last section of this paper. Besides the optical gain is analyzed and calculated. The antenna system can be tiled up to four channels but without the increase of thickness.

  1. Analysis and design of terahertz antennas based on plasmonic resonant graphene sheets

    SciTech Connect

    Tamagnone, M.; Gomez-Diaz, J. S.; Perruisseau-Carrier, J.

    2012-12-01

    Resonant graphene antennas used as true interfaces between terahertz (THz) space waves and a source/detector are presented. It is shown that in addition to the high miniaturization related to the plasmonic nature of the resonance, graphene-based THz antenna favorably compare with typical metal implementations in terms of return loss and radiation efficiency. Graphene antennas will contribute to the development of miniature, efficient, and potentially transparent all-graphene THz transceivers for emerging communication and sensing application.

  2. Theoretical analysis, design and development of a 27-MHz folded loop antenna as a potential applicator in hyperthermia treatment.

    PubMed

    Kouloulias, Vassilis; Karanasiou, Irene; Giamalaki, Melina; Matsopoulos, George; Kouvaris, John; Kelekis, Nikolaos; Uzunoglu, Nikolaos

    2015-02-01

    A hyperthermia system using a folded loop antenna applicator at 27 MHz for soft tissue treatment was investigated both theoretically and experimentally to evaluate its clinical value. The electromagnetic analysis of a 27-MHz folded loop antenna for use in human tissue was based on a customised software tool and led to the design and development of the proposed hyperthermia system. The system was experimentally validated using specific absorption rate (SAR) distribution estimations through temperature distribution measurements of a muscle tissue phantom after electromagnetic exposure. Various scenarios for optimal antenna positioning were also performed. Comparison of the theoretical and experimental analysis results shows satisfactory agreement. The SAR level of 50% reaches 8 cm depth in the tissue phantom. Thus, based on the maximum observed SAR values that were of the order of 100 W/kg, the antenna specified is suitable for deep tumour heating. Theoretical and experimental SAR distribution results as derived from this study are in agreement. The proposed folded loop antenna seems appropriate for use in hyperthermia treatment, achieving proper planning and local treatment of deeply seated affected areas and lesions.

  3. Gain enhancement for wideband end-fire antenna design with artificial material.

    PubMed

    Wei, Min; Sun, Yuanhua; Wu, Xi; Wen, Wu

    2016-01-01

    Gain enhancement wideband end-fire antenna is proposed in this paper. The proposed antenna can achieve gain enhancement by loading novel artificial materials structures (Split-ring Resonators) in the end-fire direction while broad bandwidth is realized by using elliptic dipole elements and a microstrip to coplanar balun. The measurements show that the proposed antenna have around 5-8 dB gain in the working band (5-11 GHz), which is around 2 dB more than the unloaded one. This antenna can be used in target recognition systems for its advantages of end-fire radiation broad bandwidth and high gain.

  4. Computational design of miniaturized microstrip antenna for satellite communications in the S and C bands

    NASA Astrophysics Data System (ADS)

    Marulanda Bernal, Jose Ignacio; Campo Caicedo, Damian Andres

    2014-05-01

    This paper presents computational models of microstrip antennas using the software CST. The main objective of this paper is to evaluate an alternative way to miniaturize dimensions of microstrip antennas. In order to this, a coating made of ceramic with high dielectric constant was considered for two different cases. Scattering parameters (S11) and radiation patterns were obtained for both structures and compared with standard microstrip antennas for S and C bands. Finally, the results show the possibility of reducing the dimensions by 22% to 31% and demonstrate the feasibility for the implementation and development of these antennas.

  5. Design of long-pulse fast wave current drive antennas for DIII-D

    NASA Astrophysics Data System (ADS)

    Baity, F. W.; Batchelor, D. B.; Bills, K. C.; Fogelman, C. H.; Jaeger, E. F.; Ping, J. L.; Riemer, B. W.; Ryan, P. M.; Stallings, D. C.; Taylor, D. J.; Yugo, J. J.

    1994-10-01

    Two new long-pulse fast wave current drive (FWCD) antennas will be installed on DIII-D in early 1994. These antennas will increase the available FWCD power from 2 MW to 6 MW for pulse lengths of up to 2 s, and to 4 MW for up to 10 s. Power for the new antennas is from two ASDEX-type 30- to 120-MHz transmitters. When operated at 90° phasing into a low-density plasma (˜4×1019m-3) with hot electrons (˜10 keV), these two new antennas are predicted to drive approximately 1 MA of plasma current.

  6. Design of smoothed multi-flared antenna for multi-frequency reception of direct transmission from meteorological satellites

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Kesarkar, Amit P.; Thawait, Prateek

    2016-07-01

    The direct radiance data assimilation is found to be advantageous for the numerical weather prediction over short and medium range. Therefore reception of satellite radiance in real time is important. Satellite earth station is the preferred choice for direct reception of this data, which is voluminous. High Rate Information being transmitted from these satellites operating in L, S, C and X bands needs to be received. A commercial wide band antenna is not preferred for such application, as it operates uniformly over the entire frequency range in these bands and may create interference over the unwanted frequencies. As the frequencies of interest occupy only a small portion of these bands, it is essential to design a horn antenna, which receives only specified frequencies and filter other frequencies. In this work, we have designed a multi-flare multi-frequency cylindrical horn antenna for reception of direct transmission from meteorological satellites. This earth station antenna tracks selected satellites working over specified frequency ranges, which are 1.694-1.703 GHz, 2.0-2.06 GHz, 4.5-4.6 GHz and 7.8-7.9 GHz in L, S, C and X bands respectively. Cylindrical waveguides for the frequencies, 1.6, 2, 4.5 and 8 GHz are designed and they are joined in the increasing order of radius with suitable conical shapes. The slope of the cones is adjusted experimentally. With this design, the return loss is simulated and found to be better than 20 dB upto 4.5 GHz and later it became poor. To overcome this difficulty, the abrupt transitions at the joints of the conical and cylindrical waveguides are made smoothen by increasing the diameter of one mouth of the cylinder and reducing the other mouth to match with the cylinders corresponding to next higher and lower frequency respectively. As a result, a smooth flared antenna is obtained and the simulated results are satisfactory. A parabolic reflector of 4 m diameter is designed and the smooth multi-flared antenna is kept at the

  7. 15. DETAIL OF IRON STRAP AT JUNCTURE OF CENTRAL ROOF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. DETAIL OF IRON STRAP AT JUNCTURE OF CENTRAL ROOF SUPPORT TRUSS LOWER CHORD AND INCLINED END POST. BOLTING FOR LAMINATED WOODED TRUSS ELEMENTS ALSO VISIBLE. - Saratoga Gas Light Company, Gasholder No. 2, Niagara Mohawk Power Corporation Substation Facility, intersection of Excelsior & East Avenues, Saratoga Springs, NY

  8. The Enhanced Performance Launcher Design For The ITER Upper Port ECH Antenna

    SciTech Connect

    Henderson, M. A.; Chavan, R.; Bertizzolo, R.; Duron, J.; Landis, J.-D.; Sauter, O.; Sanchez, F.; Shidara, H.; Udintsev, V. S.; Zucca, C.; Bruschi, A.; Criant, S.; Farina, D.; Ramponi, G.; Heidinger, R.; Poli, E.; Zohm, H.; Saibene, G.

    2007-09-28

    The ITER ECH heating and current drive system delivers 24 MW (170 GHz), which can be directed to either the equatorial (EL) or upper (UL) port launching antennas depending on the desired physics application. The UL design uses two front steering (FS) mirrors that sweep eight beams in a poloidal plane providing co-ECCD over the outer half of the plasma cross section. A novel frictionless, backlash-free steering mechanism has been developed for an increased reliability and providing a steering mirror rotation of up to {+-}7 deg. ({+-}14 deg. for RF beam). The principle aim of the UL is to stabilize the neoclassical tearing modes (NTM) and (by extending the steering range) access the q = 1 flux surface for control of the sawtooth oscillation. Increasing the range of the UL can relax the EL steering range, and optimize the EL for enhanced performance with an optimized central deposition and potential for counter ECCD. This paper will summarize the present UL design status along with the proposed design modifications to the UL for enhanced performance and increased reliability.

  9. Design of High Impedance Electromagnetic Surfaces for Mutual Coupling Reduction in Patch Antenna Array.

    PubMed

    Islam, Mohammad Tariqul; Alam, Md Shahidul

    2013-01-07

    A compact planar meander-bridge high impedance electromagnetic structure (MBHIES) was designed and its bandgap characteristics, mutual coupling reduction abilities were studied and compared in detail. Several parametric analyses were performed to obtain optimized design values and the transmission responses were calculated through the suspended microstrip line and waveguide simulation methods. The achieved bandgap is 2.3 GHz (2.55-4.85 GHz) with -61 dB minimum transmission coefficient level at the center frequency of 3.6 GHz. To see the effectiveness, the proposed design was inserted between a microstrip patch antenna array which operates at 3.8 GHz and whose operating bandwidth falls within the MBHIES bandgap. The surface wave suppression phenomenon was analyzed and simulated results are verified by measuring the fabricated prototypes, both are in good agreement. The configuration reduced the mutual coupling by 20.69 dB in simulation and 19.18 dB in measurement, without affecting the radiation characteristics of the array but increasing the gain slightly.

  10. JPL antenna technology development

    NASA Technical Reports Server (NTRS)

    Freeland, R. E.

    1981-01-01

    Plans for evaluating, designing, fabricating, transporting and deploying cost effective and STS compatible offset wrap rib antennas up to 300 meters in diameter for mobile communications, Earth resources observation, and for the orbiting VLBI are reviewed. The JPL surface measurement system, intended for large mesh deployable antenna applications will be demonstrated and validated as part of the antenna ground based demonstration program. Results of the offset wrap rib deployable antenna technology development will include: (1) high confidence structural designs for antennas up to 100 meters in diameter; (2) high confidence estimates of functional performance and fabrication cost for a wide range of antenna sizes (up to 300 meters in diameter); (3) risk assessment for fabricating the large size antennas; and (4) 55 meter diameter flight quality hardware that can be cost effectively completed toto accommodate a flight experiment and/or application.

  11. Horn antenna design studies. Citations from the International Aerospace Abstract data base

    NASA Technical Reports Server (NTRS)

    Gallagher, M. K.

    1980-01-01

    These citations from the international literature describe the antenna radiation patterns, polarization characteristics, wave propagation, noise temperature, wave diffraction, and wideband communication of various horn antennas. This updated bibliography contains 217 citations, 63 of which are new entries to the previous edition.

  12. Resonant optical antennas.

    PubMed

    Mühlschlegel, P; Eisler, H-J; Martin, O J F; Hecht, B; Pohl, D W

    2005-06-10

    We have fabricated nanometer-scale gold dipole antennas designed to be resonant at optical frequencies. On resonance, strong field enhancement in the antenna feed gap leads to white-light supercontinuum generation. The antenna length at resonance is considerably shorter than one-half the wavelength of the incident light. This is in contradiction to classical antenna theory but in qualitative accordance with computer simulations that take into account the finite metallic conductivity at optical frequencies. Because optical antennas link propagating radiation and confined/enhanced optical fields, they should find applications in optical characterization, manipulation of nanostructures, and optical information processing.

  13. Design considerations for rectangular microstrip patch antenna on electromagnetic crystal substrate at terahertz frequency

    NASA Astrophysics Data System (ADS)

    Singh, G.

    2010-01-01

    The effects of 2-D electromagnetic crystal substrate on the performance of a rectangular microstrip patch antennas at THz frequencies is simulated. Electromagnetic crystal substrate is used to obtain extremely broad-bandwidth with multi-frequency band operation of the proposed microstrip antennas. Multi-frequency band microstrip patch antennas are used in modern communication systems in order to enhance their capacity through frequency reuse. The simulated 10 dB impedance bandwidth of the rectangular patch microstrip antenna is 34.3% at THz frequency (0.6-0.95 THz). The radiation efficiency, gain and directivity of the proposed antenna are presented at different THz frequencies. The simulation has been performed using CST Microwave Studio, which is a commercially available electromagnetic simulator based on finite integral technique.

  14. Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears

    PubMed Central

    Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

    2016-01-01

    In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor. PMID:27472331

  15. Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears.

    PubMed

    Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

    2016-07-26

    In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor.

  16. Analysis and design of ring-resonator integrated hemi-elliptical lens antenna at terahertz frequency

    NASA Astrophysics Data System (ADS)

    Jha, Kumud Ranjan; Singh, G.

    2012-07-01

    In this paper, a novel lens integrated ring-resonator microstrip antenna is analyzed and simulated at 600 GHz. A mathematical model to compute the directivity of this kind of the antenna has been developed and the directivity of the antenna has been computed which is 18 dBi. The proposed model has been simulated by using CST Microwave Studio a commercially available simulator based on finite integral technique and similar result has been obtained. Further, the directivity of the antenna has also been computed by using the techniques reported in the literature and in this case also we have obtained the similar result. Later, a probe-fed patch integrated lens antenna has also been investigated to validate the correctness of the numerical method. To find the potential advantages of this kind of the structure, the - 10 dB impedance bandwidth of the antenna has been compared to a lens-integrated probe-fed microstrip patch antenna and a significant enhancement in the bandwidth has been observed.

  17. Design and Performance Evaluation of a Dual Antenna Joint Carrier Tracking Loop

    PubMed Central

    Guo, Wenfei; Lin, Tao; Niu, Xiaoji; Shi, Chuang; Zhang, Hongping

    2015-01-01

    In order to track the carrier phases of Global Navigation Satellite Systems (GNSS) signals in signal degraded environments, a dual antenna joint carrier tracking loop is proposed and evaluated. This proposed tracking loop processes inputs from two antennas, namely the master antenna and the slave antenna. The master antenna captures signals in open-sky environments, while the slave antenna capture signals in degraded environments. In this architecture, a Phase Lock Loop (PLL) is adopted as a master loop to track the carrier phase of the open-sky signals. The Doppler frequency estimated by this master loop is utilized to assist weak carrier tracking in the slave loop. As both antennas experience similar signal dynamics due to satellite motion and clock frequency variations, a much narrower loop bandwidth and possibly a longer coherent integration can be adopted to track the weak signals in slave channels, by utilizing the Doppler aid from master channels. PLL tracking performance is affected by the satellite/user dynamics, clock instability, and thermal noise. In this paper, their impacts on the proposed phase tracking loop are analyzed and verified by both simulation and field data. Theoretical analysis and experimental results show that the proposed loop structure can track degraded signals (i.e., 18 dB-Hz) with a very narrow loop bandwidth (i.e., 0.5 Hz) and a TCXO clock. PMID:26437415

  18. Design and Performance Evaluation of a Dual Antenna Joint Carrier Tracking Loop.

    PubMed

    Guo, Wenfei; Lin, Tao; Niu, Xiaoji; Shi, Chuang; Zhang, Hongping

    2015-10-01

    In order to track the carrier phases of Global Navigation Satellite Systems (GNSS) signals in signal degraded environments, a dual antenna joint carrier tracking loop is proposed and evaluated. This proposed tracking loop processes inputs from two antennas, namely the master antenna and the slave antenna. The master antenna captures signals in open-sky environments, while the slave antenna capture signals in degraded environments. In this architecture, a Phase Lock Loop (PLL) is adopted as a master loop to track the carrier phase of the open-sky signals. The Doppler frequency estimated by this master loop is utilized to assist weak carrier tracking in the slave loop. As both antennas experience similar signal dynamics due to satellite motion and clock frequency variations, a much narrower loop bandwidth and possibly a longer coherent integration can be adopted to track the weak signals in slave channels, by utilizing the Doppler aid from master channels. PLL tracking performance is affected by the satellite/user dynamics, clock instability, and thermal noise. In this paper, their impacts on the proposed phase tracking loop are analyzed and verified by both simulation and field data. Theoretical analysis and experimental results show that the proposed loop structure can track degraded signals (i.e., 18 dB-Hz) with a very narrow loop bandwidth (i.e., 0.5 Hz) and a TCXO clock.

  19. The design of RFID convey or belt gate systems using an antenna control unit.

    PubMed

    Park, Chong Ryol; Lee, Seung Joon; Eom, Ki Hwan

    2011-01-01

    This paper proposes an efficient management system utilizing a Radio Frequency Identification (RFID) antenna control unit which is moving along with the path of boxes of materials on the conveyor belt by manipulating a motor. The proposed antenna control unit, which is driven by a motor and is located on top of the gate, has an array structure of two antennas with parallel connection. The array structure helps improve the directivity of antenna beam pattern and the readable RFID distance due to its configuration. In the experiments, as the control unit follows moving materials, the reading time has been improved by almost three-fold compared to an RFID system employing conventional fixed antennas. The proposed system also has a recognition rate of over 99% without additional antennas for detecting the sides of a box of materials. The recognition rate meets the conditions recommended by the Electronic Product Code glbal network (EPC)global for commercializing the system, with three antennas at a 20 dBm power of reader and a conveyor belt speed of 3.17 m/s. This will enable a host of new RFID conveyor belt gate systems with increased performance.

  20. The Design of RFID Convey or Belt Gate Systems Using an Antenna Control Unit

    PubMed Central

    Park, Chong Ryol; Lee, Seung Joon; Eom, Ki Hwan

    2011-01-01

    This paper proposes an efficient management system utilizing a Radio Frequency Identification (RFID) antenna control unit which is moving along with the path of boxes of materials on the conveyor belt by manipulating a motor. The proposed antenna control unit, which is driven by a motor and is located on top of the gate, has an array structure of two antennas with parallel connection. The array structure helps improve the directivity of antenna beam pattern and the readable RFID distance due to its configuration. In the experiments, as the control unit follows moving materials, the reading time has been improved by almost three-fold compared to an RFID system employing conventional fixed antennas. The proposed system also has a recognition rate of over 99% without additional antennas for detecting the sides of a box of materials. The recognition rate meets the conditions recommended by the Electronic Product Code glbal network (EPC)global for commercializing the system, with three antennas at a 20 dBm power of reader and a conveyor belt speed of 3.17 m/s. This will enable a host of new RFID conveyor belt gate systems with increased performance. PMID:22164119

  1. New design concept of monopole antenna array for UHF 7T MRI.

    PubMed

    Hong, Suk-Min; Park, Joshua Haekyun; Woo, Myung-Kyun; Kim, Young-Bo; Cho, Zang-Hee

    2014-05-01

    We have developed and evaluated a monopole antenna array that can increase sensitivity at the center of the brain for 7T MRI applications. We have developed a monopole antenna array that has half the length of a conventional dipole antenna with eight channels for brain imaging with a 7T MRI. The eight-channel monopole antenna array and conventional eight-channel transceiver surface coil array were evaluated and compared in terms of transmit properties, specific absorption ratio (SAR), and sensitivity. The sensitivity maps were generated by dividing the SNR map by the flip angle distribution. A single surface coil provides asymmetric sensitivity resulting in reduced sensitivity at the center of the brain. In contrast, a single monopole antenna provides higher sensitivity at the center of the brain. Moreover, the monopole antenna array provides uniform sensitivity over the entire brain, and the sensitivity gain was 1.5 times higher at the center of the brain compared with the surface coil array. The monopole antenna array is a promising candidate for MRI applications, especially for brain imaging in a 7T MRI because it provides increased sensitivity at the center of the brain. Copyright © 2013 Wiley Periodicals, Inc.

  2. Design of a radiative surface coil array element at 7 T: the single-side adapted dipole antenna.

    PubMed

    Raaijmakers, A J E; Ipek, O; Klomp, D W J; Possanzini, C; Harvey, P R; Lagendijk, J J W; van den Berg, C A T

    2011-11-01

    Ultra high field MR imaging (≥7 T) of deeply located targets in the body is facing some radiofrequency-field related challenges: interference patterns, reduced penetration depth, and higher Specific Absorbtion Ratio (SAR) levels. These can be alleviated by redesigning the elements of the transmit or transceive array. This is because at these high excitation field (B(1) ) frequencies, conventional array element designs may have become suboptimal. In this work, an alternative design approach is presented, regarding coil array elements as antennas. Following this approach, the Poynting vector of the element should be oriented towards the imaging target region. The single-side adapted dipole antenna is a novel design that fulfills this requirement. The performance of this design as a transmit coil array element has been characterized by comparison with three other, more conventional designs using finite difference time domain (FDTD) simulations and B +1 measurements on a phantom. Results show that the B +1 level at the deeper regions is higher while maintaining relatively low SAR levels. Also, the B +1 field distribution is more symmetrical and more uniform, promising better image homogeneity. Eight radiative antennas have been combined into a belt-like surface array for prostate imaging. T(1) -weighted (T1W) and T(2) -weighted (T2W) volunteer images are presented along with B +1 measurements to demonstrate the improved efficiency. Copyright © 2011 Wiley Periodicals, Inc.

  3. Design Criteria and Numerical Simulation of an Antenna System for One Dimensional Limited Scan

    DTIC Science & Technology

    1975-12-02

    Antenna System for One-Dimensional Limited Scan GIORGIO V. BORGIOTTI 2 December 1975 D D C n(_APR 6 ,976 iifi uteEinnsJlil V Approval for public...YSTEM FOR ONE-DIMENSIONAL LIMITED SCAN. /,/ In Hi 01 * <’ il* _ ’ ..wji.li m ’ Giorgio V /yfeorgiotti I SSSSSS i THII n ijC i »m»mw-——mnaa...Idontlty AT Aloe* nummof) Limited scan arrays Antenna systems Phased arrays Antenna theory STRACT (Canlln> •vor«« aid* It nocoaoory and tdonnly br

  4. Antenna Measurement and Design for the CanX-7 Nanosatellite and the Development of a Global Navigation Satellite System Based Attitude Determination System

    NASA Astrophysics Data System (ADS)

    Ang, Paris Yen-Jun

    This thesis describes and presents solutions to various challenges small satellites may encounter during design and operation, particularly in the areas of communications and attitude determination. The first section of this thesis presents simulation and measurement of communications antennas on a nanosatellite to verify that the antennas have sufficient gain and polarization to enable near-omnidirectional operation. Near-omnidirectional antennas are essential to ensure reliable communication with the spacecraft regardless of its attitude, especially when fine pointing ability is unavailable or inadequate. Next, the following section covers the design of a circularly polarized patch antenna for use on an aircraft tracking payload. Lastly, the final section of this thesis presents the development and analysis of a technique for augmenting a single GPS antenna on a spacecraft to estimate attitude. It is possible for GPS measurements to partially supplement an existing attitude sensor that has been denied operation.

  5. Design and fabrication of an E-shaped wearable textile antenna on PVB-coated hydrophobic polyester fabric

    NASA Astrophysics Data System (ADS)

    Babu Roshni, Satheesh; Jayakrishnan, M. P.; Mohanan, P.; Peethambharan Surendran, Kuzhichalil

    2017-10-01

    In this paper, we investigated the simulation and fabrication of an E-shaped microstrip patch antenna realized on multilayered polyester fabric suitable for WiMAX (Worldwide Interoperability for Microwave Access) applications. The main challenges while designing a textile antenna were to provide adequate thickness, surface uniformity and water wettability to the textile substrate. Here, three layers of polyester fabric were stacked together in order to obtain sufficient thickness, and were subsequently dip coated with polyvinyl butyral (PVB) solution. The PVB-coated polyester fabric showed a hydrophobic nature with a contact angle of 91°. The RMS roughness of the uncoated and PVB-coated polyester fabric was about 341 nm and 15 nm respectively. The promising properties, such as their flexibility, light weight and cost effectiveness, enable effortless integration of the proposed antenna into clothes like polyester jackets. Simulated and measured results in terms of return loss as well as gain were showcased to confirm the usefulness of the fabricated prototype. The fabricated antenna successfully operates at 3.37 GHz with a return loss of 21 dB and a maximum measured gain of 3.6 dB.

  6. Shuttle orbiter Ku-band radar/communications system design evaluation: High gain antenna/widebeam horn

    NASA Technical Reports Server (NTRS)

    Iwasaki, R.; Dodds, J. G.; Broad, P.

    1979-01-01

    The physical characteristics of the high gain antenna reflector and feed elements are described. Deficiencies in the sum feed are discussed, and lack of atmospheric venting is posed as a potential problem area. The measured RF performance of the high gain antenna is examined and the high sidelobe levels measured are related to the physical characteristics of the antenna. An examination of the attributes of the feed which might be influenced by temperature extremes shows that the antenna should be insensitive to temperature variations. Because the feed support bipod structure is considered a significant contributor to the high sidelobe levels measured in the azimuth plane, pod relocation, material changes, and shaping are suggested as improvements. Alternate feed designs are presented to further improve system performance. The widebeam horn and potential temperature effects due to the polarizer are discussed as well as in the effects of linear polarization on TDRS acquisition, and the effects of circular polarization on radar sidelobe avoidance. The radar detection probability is analyzed as a function of scan overlap and target range.

  7. Design of long-pulse fast wave current drive antennas for DIII-D

    SciTech Connect

    Baity, F.W.; Batchelor, D.B.; Bills, K.C.; Fogelman, C.H.; Jaeger, E.F.; Ping, J.L.; Riemer, B.W.; Ryan, P.M.; Stallings, D.C.; Taylor, D.J.; Yugo, J.J. )

    1994-10-15

    Two new long-pulse fast wave current drive (FWCD) antennas will be installed on DIII-D in early 1994. These antennas will increase the available FWCD power from 2 MW to 6 MW for pulse lengths of up to 2 s, and to 4 MW for up to 10 s. Power for the new antennas is from two ASDEX-type 30- to 120-MHz transmitters. When operated at 90[degree] phasing into a low-density plasma ([similar to]4[times]10[sup 19]m[sup [minus]3]) with hot electrons ([similar to]10 keV), these two new antennas are predicted to drive approximately 1 MA of plasma current.

  8. Antenna and coil design for wireless signal detection and charging of embedded power active contact lens.

    PubMed

    Ng, Benny; Heckler, Paul; Do, Alex; Azar, Phillip; Leon, Errol; Smilkstein, Tina

    2014-01-01

    This paper presents a screen printed 2.4 GHz antenna and induction charging coil for an active contact lens with a single large pixel user display and on-board 3.8 V 5 uAh rechargeable battery. The antenna traces are printed using silver conductive paste on a 25 um polyethylene terephthalate (PET) substrate. The incoming signal from the antenna feeds into an IC that amplifies and rectifies the signal. The coil provides wireless energy transfer to inductively charge a thin film battery [1] located on the contact lens. The printed antenna achieved a S11 of -4 dB at 2.4 GHz and a gain of -13 dB.

  9. Impact of Optical Baffle on Antenna Pattern

    NASA Technical Reports Server (NTRS)

    Wu, T.; Pogorzelski, R.

    1994-01-01

    One of the major concerns of antenna design for spacecraft applications is the effect of surrounding structures which can reflect and diffract the antenna's radiated energy and cause degradation in the antenna directivity, beam shape, and sidelobe levels.

  10. Impact of Optical Baffle on Antenna Pattern

    NASA Technical Reports Server (NTRS)

    Wu, T.; Pogorzelski, R.

    1994-01-01

    One of the major concerns of antenna design for spacecraft applications is the effect of surrounding structures which can reflect and diffract the antenna's radiated energy and cause degradation in the antenna directivity, beam shape, and sidelobe levels.

  11. Antenna Design Method and Performance Improvement of a Micro Ion Engine Using Microwave Discharge

    NASA Astrophysics Data System (ADS)

    Koizumi, Hiroyuki; Kuninaka, Hitoshi

    In this study, we are proposing a novel miniaturized ion engine system µ1. Recently microspacecraft and propulsion system to be installed there have attracted a lot of attentions. To accomplish the miniaturization of spacecraft component, multifunctionalization of devices are key technologies. The ion engine we are proposing here is distributed on microspacecraft and give a number of functions and strong redundancy to the spacecraft. To realize this concept, we introduced a novel idea for an ion engine system. That is to use single plasma source as both ion beam source and neutralizing electron source only by electrical connection. This ion engine system is released from the necessity of a number of neutralizers. Our concept requires a plasma source driven by very low power microwave. Here we proposed an antenna design method for a small plasma source using microwave discharge, and developed a miniaturized ion engine. As a result, the performance of the miniaturized ion engine was improved up to the ion production cost of 240 V and propellant utilization efficiency of 40 % at the input microwave power of 1.0 W and mass flow rate of 0.15 sccm.

  12. Cross-layer Design for MIMO Systems with Transmit Antenna Selection and Imperfect CSI

    NASA Astrophysics Data System (ADS)

    Yu, Xiangbin; Liu, Yan; Rui, Yun; Zhou, Tingting; Yin, Xin

    2013-04-01

    In this paper, by combining adaptive modulation and automatic repeat request (ARQ), a cross-layer design (CLD) scheme for multiple-input and multiple-output (MIMO) system with transmit antenna selection (TAS) and imperfect channel state information (CSI) is presented. Based on the imperfect CSI, the probability density function of the effective signal to noise ratio (SNR) is derived, and the fading gain switching thresholds are also derived subject to a target packet loss rate and fixed power constraint. According to these results, we further derive the average spectrum efficiency (SE) and packet error rate (PER) of the system. As a result, closed-form expressions of the average SE and PER are obtained, respectively. The derived expressions include the expressions under perfect CSI as special cases, and can provide good performance evaluation for the CLD system with imperfect CSI. Simulation results verify the validity of the theoretical analysis. The results show that the CLD system with TAS provides better SE than that with space-time block coding, but the SE and PER performance of the system with imperfect CSI are worse than those with perfect CSI due to the estimation error.

  13. Cellular Reflectarray Antenna

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2010-01-01

    The cellular reflectarray antenna is intended to replace conventional parabolic reflectors that must be physically aligned with a particular satellite in geostationary orbit. These arrays are designed for specified geographical locations, defined by latitude and longitude, each called a "cell." A particular cell occupies nominally 1,500 square miles (3,885 sq. km), but this varies according to latitude and longitude. The cellular reflectarray antenna designed for a particular cell is simply positioned to align with magnetic North, and the antenna surface is level (parallel to the ground). A given cellular reflectarray antenna will not operate in any other cell.

  14. Astronaut Joseph Kerwin strapped into sleep restraint in crew quarters

    NASA Image and Video Library

    1973-06-01

    Scientist-Astronaut Joseph P. Kerwin, Skylab 2 science pilot, is photographed strapped into the sleep restraint in the crew quarters of the Orbital Workshop of the Skylab 1 and 2 space station cluster in Earth orbit. Kerwin is wearing the special cap which contains biomedical instrumentation for the M133 Sleep Monitoring Experiment. The purpose of the M133 experiment is to evaluate quantity and quality of sleep during prolonged space flight by the analysis of electroencephalographic (EEG) and electrooculographic (EOG) activity.

  15. Astronaut Joseph Kerwin strapped into sleep restraint in crew quarters

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Scientist-Astronaut Joseph P. Kerwin, Skylab 2 science pilot, is photographed strapped into the sleep restraint in the crew quarters of the Orbital Workshop of the Skylab 1 and 2 space station cluster in Earth orbit. Kerwin is wearing the special cap which contains biomedical instrumentation for the M133 Sleep Monitoring Experiment. The purpose of the M133 experiment is to evaluate quantity and quality of sleep during prolonged space flight by the analysis of electroencephalographic (EEG) and electrooculographic (EOG) activity.

  16. Hiking strap force decreases during sustained upwind sailing.

    PubMed

    Buchardt, R; Bay, J; Bojsen-Møller, J; Nordsborg, N B

    2017-05-01

    The hypothesis, that sailing upwind in wind speeds above 12 knots causes fatigue, which manifests as a reduction in exerted hiking strap force and/or maximal isometric voluntary contraction force (MVC) of the knee extensors, was evaluated. Additionally, it was investigated if a relationship exists between maximal exerted hiking force (hMVC) and sailing performance. In part 1 of the study, 12 national level athletes sailed upwind for 2 × 10 min while hiking strap forces were continuously acquired. Before, in between and after sailing periods, the MVC of the knee extensors was measured. In part 2 of the study, hMVC was measured dry land in a hiking bench and correlated with the overall results at a national championship. Hiking strap force decreased from the first to the last minute in both 10 min sailing periods (430 ± 131 vs. 285 ± 130 N, P < .001 and 369 ± 74 vs. 267 ± 97 N, P < .001, respectively), but MVC was similar before, between and after the two 10 min sailing periods (878 ± 215 vs. 852 ± 202 vs. 844 ± 211 130 N). In part 2, a significant positive correlation (r(2) = 0.619, P < .01) was observed between hMVC and regatta results. In conclusion, upwind sailing in wind speeds above 12 knots causes sailing-specific fatigue as evidenced by a marked reduction in exerted hiking strap force. However, MVC of the knee extensors was not compromised ∼45 s after hiking was terminated. Additionally, sailing performance is related to maximal hiking force.

  17. Design and implementation of a beam-waveguide mirror control system for vernier pointing of the DSS-13 antenna

    NASA Technical Reports Server (NTRS)

    Alvarez, L. S.; Moore, M.; Veruttipong, W.; Andres, E.

    1994-01-01

    The design and implementation of an antenna beam-waveguide (BWG) mirror position control system at the DSS-13 34-m antenna is presented. While it has several potential applications, a positioner on the last flat-plate BWG mirror (M6) at DSS 13 is installed to demonstrate the conical scan (conscan) angle-tracking technique at the Ka-band (32-GHz) operating frequency. Radio frequency (RF) beam-scanning predictions for the M6 mirror, computed from a diffraction analysis, are presented. From these predictions, position control system requirements are then derived. The final mechanical positioner and servo system designs, as implemented at DSS 13, are illustrated with detailed design descriptions given in the appendices. Preliminary measurements of antenna Ka-band beam scan versus M6 mirror tilt made at DSS 13 in December 1993 are presented. After reduction, the initial measurements are shown to be in agreement with the RF predicts. Plans for preliminary conscan experimentation at DSS 13 are summarized.

  18. Real-Time Strap Pressure Sensor System for Powered Exoskeletons

    PubMed Central

    Tamez-Duque, Jesús; Cobian-Ugalde, Rebeca; Kilicarslan, Atilla; Venkatakrishnan, Anusha; Soto, Rogelio; Contreras-Vidal, Jose Luis

    2015-01-01

    Assistive and rehabilitative powered exoskeletons for spinal cord injury (SCI) and stroke subjects have recently reached the clinic. Proper tension and joint alignment are critical to ensuring safety. Challenges still exist in adjustment and fitting, with most current systems depending on personnel experience for appropriate individual fastening. Paraplegia and tetraplegia patients using these devices have impaired sensation and cannot signal if straps are uncomfortable or painful. Excessive pressure and blood-flow restriction can lead to skin ulcers, necrotic tissue and infections. Tension must be just enough to prevent slipping and maintain posture. Research in pressure dynamics is extensive for wheelchairs and mattresses, but little research has been done on exoskeleton straps. We present a system to monitor pressure exerted by physical human-machine interfaces and provide data about levels of skin/body pressure in fastening straps. The system consists of sensing arrays, signal processing hardware with wireless transmission, and an interactive GUI. For validation, a lower-body powered exoskeleton carrying the full weight of users was used. Experimental trials were conducted with one SCI and one able-bodied subject. The system can help prevent skin injuries related to excessive pressure in mobility-impaired patients using powered exoskeletons, supporting functionality, independence and better overall quality of life. PMID:25690551

  19. Real-time strap pressure sensor system for powered exoskeletons.

    PubMed

    Tamez-Duque, Jesús; Cobian-Ugalde, Rebeca; Kilicarslan, Atilla; Venkatakrishnan, Anusha; Soto, Rogelio; Contreras-Vidal, Jose Luis

    2015-02-16

    Assistive and rehabilitative powered exoskeletons for spinal cord injury (SCI) and stroke subjects have recently reached the clinic. Proper tension and joint alignment are critical to ensuring safety. Challenges still exist in adjustment and fitting, with most current systems depending on personnel experience for appropriate individual fastening. Paraplegia and tetraplegia patients using these devices have impaired sensation and cannot signal if straps are uncomfortable or painful. Excessive pressure and blood-flow restriction can lead to skin ulcers, necrotic tissue and infections. Tension must be just enough to prevent slipping and maintain posture. Research in pressure dynamics is extensive for wheelchairs and mattresses, but little research has been done on exoskeleton straps. We present a system to monitor pressure exerted by physical human-machine interfaces and provide data about levels of skin/body pressure in fastening straps. The system consists of sensing arrays, signal processing hardware with wireless transmission, and an interactive GUI. For validation, a lower-body powered exoskeleton carrying the full weight of users was used. Experimental trials were conducted with one SCI and one able-bodied subject. The system can help prevent skin injuries related to excessive pressure in mobility-impaired patients using powered exoskeletons, supporting functionality, independence and better overall quality of life.

  20. Lightning tests and analyses of tunnel bond straps and shielded cables on the Space Shuttle solid rocket booster

    NASA Technical Reports Server (NTRS)

    Druen, William M.

    1993-01-01

    The purposes of the tests and analyses described in this report are as follows: (1) determine the lightning current survivability of five alternative changed designs of the bond straps which electrically bond the solid rocket booster (SRB) systems tunnel to the solid rocket motor (SRM) case; (2) determine the amount of reduction in induced voltages on operational flight (OF) tunnel cables obtained by a modified design of tunnel bond straps (both tunnel cover-to-cover and cover-to-motor case); (3) determine the contribution of coupling to the OF tunnel cables by ground electrical and instrumentation (GEI) cables which enter the systems tunnel from unshielded areas on the surfaces of the motor case; and (4) develop a model (based on test data) and calculate the voltage levels at electronic 'black boxes' connected to the OF cables that run in the systems tunnel.

  1. Design and characterisation of a phased antenna array for intact breast hyperthermia.

    PubMed

    Curto, Sergio; Garcia-Miquel, Aleix; Suh, Minyoung; Vidal, Neus; Lopez-Villegas, Jose M; Prakash, Punit

    2017-06-28

    Currently available hyperthermia technology is not well suited to treating cancer malignancies in the intact breast. This study investigates a microwave applicator incorporating multiple patch antennas, with the goal of facilitating controllable power deposition profiles for treating lesions at diverse locations within the intact breast. A 3D-computational model was implemented to assess power deposition profiles with 915 MHz applicators incorporating a hemispheric groundplane and configurations of 2, 4, 8, 12, 16 and 20 antennas. Hemispheric breast models of 90 mm and 150 mm diameter were considered, where cuboid target volumes of 10 mm edge length (1 cm(3)) and 30 mm edge length (27 cm(3)) were positioned at the centre of the breast, and also located 15 mm from the chest wall. The average power absorption (αPA) ratio expressed as the ratio of the PA in the target volume and in the full breast was evaluated. A 4-antenna proof-of-concept array was fabricated and experimentally evaluated. Computational models identified an optimal inter-antenna spacing of 22.5° along the applicator circumference. Applicators with 8 and 12 antennas excited with constant phase presented the highest αPA at centrally located and deep-seated targets, respectively. Experimental measurements with a 4-antenna proof-of-concept array illustrated the potential for electrically steering power deposition profiles by adjusting the relative phase of the signal at antenna inputs. Computational models and experimental results suggest that the proposed applicator may have potential for delivering conformal thermal therapy in the intact breast.

  2. Embedded Meta-Material Antennas

    DTIC Science & Technology

    2009-01-31

    of electronic warfare signal and information processing systems. To realize such systems, the key is to miniaturize antennas that transmit and...single aperture, which can provide significant miniaturization and flexibility to the entire system. To design such miniaturized antennas , new materials...and technologies have to be incorporated. For this purpose, the PI has designed and demonstrated miniaturized antennas by introducing metamaterials

  3. Design of a composite right/left-handed transmission line unit-cell for a U-shaped mushroom ZOR antenna based on left-handed metamaterials

    NASA Astrophysics Data System (ADS)

    Lee, Cherl-Hee; Lee, Jonghun; Woo, Dong-Sik; Kim, Kang-Wook

    2012-11-01

    In this paper, a metamaterial-based zeroth-order (ZOR) mushroom antenna is presented by using a new composite right/left-handed (CRLH) transmission line unit-cell implemented with a U-shaped top plate is presented to extend bandwidth. The ZOR antenna whose resonance frequency is independent of the antenna size can enable a reduction of the antenna size. Because the shunt capacitance is determined by the area of a mushroom patch, a U-shaped mushroom having a lower shunt capacitance than the Sievenpiper mushroom structure is properly designed to widen the small bandwidth of the CRLH TL antenna. Compared to a square-shaped mushroom structure, a U-shaped mushroom structure for three unit-cells provided a reduced shunt capacitance and increased the 10-dB bandwidth by 2.5 times at 9.37 GHz.

  4. Structural synthesis of spiral antennas

    NASA Astrophysics Data System (ADS)

    Prigoda, B. A.

    2013-12-01

    This article discusses alternative designs of helical antennas used in space vehicles. The dependence of the beam shape on the number of approaches and the mode of excitation of helical antennas is shown.

  5. Design and Experiment of an Ultra-wideband Dual-Pulse Radiating Antenna

    NASA Astrophysics Data System (ADS)

    Sitao, Z.; Guozhi, L.; Chaolong, Y.; Xiaoxin, S.; Yajun, F.; Lei, S.; Wenfeng, X.; Yufeng, Z.

    A method to widen the microwave spectrum by radiating two pulses of different FWHM is presented. Based on this method, a high-power ultra-wideband dual-pulse radiating antenna is developed. The antenna is made up of a half-impulse radiating antenna (IRA) over a ground plane. The diameter of the reflector is 3 m with focal length 1.2 m and the ground plane is a rectangle of metal with length of 4 m and width of 3 m. Three TEM horns are adopted to feed two pulses into the reflector. The antenna can radiate two different bipolar pulses with peak-to-peak width of 1.7 ns and 3 ns effectively. The 3 ns bipolar pulse is after 1.7 ns bipolar pulse with a delay of 12.5 ns. Simulation analysis and experiments on the antenna are performed. Good agreements between calculated and measured results are obtained. The radiated spectrum of the 1.7 ns pulse covers from 240 MHz to 400 MHz, while the radiated spectrum of the 3 ns pulse covers from 110 MHz to 210 MHz. The radiated spectrum of the combined 1.7 ns and 3 ns dual-pulse with a 12.5 ns delay covers from 100 MHz to 430 MHz. Results show that radiating the combined pulses is a more effective method to widen the microwave spectrum than radiating a single pulse.

  6. Quadrature transmit array design using single-feed circularly polarized patch antenna for parallel transmission in MR imaging.

    PubMed

    Pang, Yong; Yu, Baiying; Vigneron, Daniel B; Zhang, Xiaoliang

    2014-02-01

    Quadrature coils are often desired in MR applications because they can improve MR sensitivity and also reduce excitation power. In this work, we propose, for the first time, a quadrature array design strategy for parallel transmission at 298 MHz using single-feed circularly polarized (CP) patch antenna technique. Each array element is a nearly square ring microstrip antenna and is fed at a point on the diagonal of the antenna to generate quadrature magnetic fields. Compared with conventional quadrature coils, the single-feed structure is much simple and compact, making the quadrature coil array design practical. Numerical simulations demonstrate that the decoupling between elements is better than -35 dB for all the elements and the RF fields are homogeneous with deep penetration and quadrature behavior in the area of interest. Bloch equation simulation is also performed to simulate the excitation procedure by using an 8-element quadrature planar patch array to demonstrate its feasibility in parallel transmission at the ultrahigh field of 7 Tesla.

  7. Quadrature transmit array design using single-feed circularly polarized patch antenna for parallel transmission in MR imaging

    PubMed Central

    Pang, Yong; Yu, Baiying; Vigneron, Daniel B.

    2014-01-01

    Quadrature coils are often desired in MR applications because they can improve MR sensitivity and also reduce excitation power. In this work, we propose, for the first time, a quadrature array design strategy for parallel transmission at 298 MHz using single-feed circularly polarized (CP) patch antenna technique. Each array element is a nearly square ring microstrip antenna and is fed at a point on the diagonal of the antenna to generate quadrature magnetic fields. Compared with conventional quadrature coils, the single-feed structure is much simple and compact, making the quadrature coil array design practical. Numerical simulations demonstrate that the decoupling between elements is better than –35 dB for all the elements and the RF fields are homogeneous with deep penetration and quadrature behavior in the area of interest. Bloch equation simulation is also performed to simulate the excitation procedure by using an 8-element quadrature planar patch array to demonstrate its feasibility in parallel transmission at the ultrahigh field of 7 Tesla. PMID:24649430

  8. A design study for the use of a multiple aperture deployable antenna for soil moisture remote sensing satellite applications

    NASA Technical Reports Server (NTRS)

    Foldes, P.

    1986-01-01

    The instrumentation problems associated with the measurement of soil moisture with a meaningful spatial and temperature resolution at a global scale are addressed. For this goal only medium term available affordable technology will be considered. The study while limited in scope, will utilize a large scale antenna structure, which is being developed presently as an experimental model. The interface constraints presented by a singel Space Transportation System (STS) flight will be assumed. Methodology consists of the following steps: review of science requirements; analyze effects of these requirements; present basic system engineering considerations and trade-offs related to orbit parameters, number of spacecraft and their lifetime, observation angles, beamwidth, crossover and swath, coverage percentage, beam quality and resolution, instrument quantities, and integration time; bracket the key system characteristics and develop an electromagnetic design of the antenna-passive radiometer system. Several aperture division combinations and feed array concepts are investigated to achieve maximum feasible performacne within the stated STS constraints.

  9. Design of a planar multiband Sierpinski E-shaped carpet antenna with CPW fed for multi standard wireless terminals

    NASA Astrophysics Data System (ADS)

    Sahu, K. Satyabrat; Panda, Asit K.

    2013-01-01

    In this paper Sierpinski E-Carpet antenna based on the implementation of fractal technique is proposed for multiband applications in 2-10 GHz band. There appeared 5 resonant frequencies at 2.35 GHz, 3.5 GHz, 5.503 GHz, 7.248GHz, and 8.79GHz for 2nd iteration. From the return loss plot it is seen that antenna achieved the IEEE Bluetooth/WLAN (2.4-2.484 GHz), WiMAX (3.4-3.69 GHz) and WIFI (5.1-5.825 GHz) frequency band with -10dB return loss. Also nearly omni-directional radiation pattern is observed. A prototype of the design is successfully implemented with close agreement between measurement and simulation result.

  10. A folded waveguide ICRF antenna for PBX-M and TFTR

    NASA Astrophysics Data System (ADS)

    Bigelow, T. S.; Carter, M. D.; Fogelman, C. H.; Yugo, J. J.; Baity, F. W.; Bell, G. L.; Gardner, W. L.; Goulding, R. H.; Hoffman, D. J.; Ryan, P. M.; Swain, D. W.; Taylor, D. J.; Wilson, R.; Bernabei, S.; Kugel, H.; Ono, M.

    1996-02-01

    The folded waveguide (FWG) antenna is an advanced ICRF launcher under development at ORNL that offers many significant advantages over current-strap type antennas. These features are particularly beneficial for reactor-relevant applications such as ITER and TPX. Previous tests of a development folded waveguide with a low density plasma load have shown a factor of 5 increase in power capability over loop antennas into similar plasma conditions. The performance and reliability of a FWG with an actual tokamak plasma load must now be verified for further acceptance of this concept. A 58 MHz, 4 MW folded waveguide is being designed and built for the PBX-M and TFTR tokamaks at Princeton Plasma Physics Laboratory. This design has a square cross-section that can be installed as either a fast wave (FW) or ion-Bernstein wave (IBW) launcher by 90° rotation. Two new features of the design are: a shorter quarter-wavelength resonator configuration and a rear-feed input power coupling loop. Loading calculations with a standard shorting plate indicate that a launched power level of 4 MW is possible on either machine. Mechanical and disruption force analysis indicates that bolted construction will withstand the disruption loads. An experimental program is planned to characterize the plasma loading, heating effectiveness, power capability, impurity generation and other factors for both FW and IBW cases. High power tests of the new configuration are being performed with a development FWG unit on RFTF at ORNL.

  11. Integrated head design using a nanobeak antenna for thermally assisted magnetic recording.

    PubMed

    Matsumoto, Takuya; Akagi, Fumiko; Mochizuki, Masafumi; Miyamoto, Harukazu; Stipe, Barry

    2012-08-13

    We propose a near-field optical transducer using a triangular antenna and a thin film structure (wing) to efficiently generate an optical near-field near a magnetic head. A finite-difference time-domain calculation showed that the near-field was efficiently generated at the apex of the antenna when the dimensions of the wing were optimized for efficient delivery of the surface plasmon excited on the wing to the antenna. The calculated light utilization efficiency (ratio between the absorbed power in the recording medium and the input power) was 8%. The temperature distribution on the medium, magnetic field distribution, and magnetization pattern were calculated; the proposed recording head may be capable of an areal recording density of 2.5 Tb/in.(2).

  12. Dual-mode antenna design for microwave heating and noninvasive thermometry of superficial tissue disease.

    PubMed

    Jacobsen, S; Stauffer, P R; Neuman, D G

    2000-11-01

    Hyperthermia therapy of superficial skin disease has proven clinically useful, but current heating equipment is somewhat clumsy and technically inadequate for many patients. The present effort describes a dual-purpose, conformal microwave applicator that is fabricated from thin, flexible, multilayer printed circuit board (PCB) material to facilitate heating of surface areas overlaying contoured anatomy. Preliminary studies document the feasibility of combining Archimedean spiral microstrip antennas, located concentrically within the central region of square dual concentric conductor (DCC) annular slot antennas. The motivation is to achieve homogeneous tissue heating simultaneously with noninvasive thermometry by radiometric sensing of blackbody radiation from the target tissue under the applicator. Results demonstrate that the two antennas have complimentary regions of influence. The DCC ring antenna structure produces a peripherally enhanced power deposition pattern with peaks in the outer corners of the aperture and a broad minimum around 50% of maximum centrally. In contrast, the Archimedean spiral radiates (or receives) energy predominantly along the boresight axis of the spiral, thus confining the region of influence to tissue located within the central broad minimum of the DCC pattern. Analysis of the temperature-dependent radiometer signal (brightness temperature) showed linear correlation of radiometer output with test load temperature using either the spiral or DCC structure as the receive antenna. The radiometric performance of the broadband Archimedean antenna was superior compared to the DCC, providing improved temperature resolution (0.1 degree C-0.2 degree C) and signal sensitivity (0.3 degree C-0.8 degree C/degree C) at all four 500 MHz integration bandwidths tested within the frequency range from 1.2 to 3.0 GHz.

  13. An experimental 20/30 GHz communications satellite conceptual design employing multiple-beam paraboloid reflector antennas

    NASA Technical Reports Server (NTRS)

    Goldman, A. M., Jr.

    1980-01-01

    An experimental 20/30 GHz communications satellite conceptual design is described which employs multiple-beam paraboloid reflector antennas coupled to a TDMA transponder. It is shown that the satellite employs solid state GaAs FET power amplifiers and low noise amplifiers while signal processing and switching takes place on-board the spacecraft. The proposed areas to be served by this satellite would be the continental U.S. plus Alaska, Hawaii, Puerto Rico, and the Virgin Islands, as well as southern Canada and Mexico City. Finally, attention is given to the earth stations which are designed to be low cost.

  14. An experimental 20/30 GHz communications satellite conceptual design employing multiple-beam paraboloid reflector antennas

    NASA Technical Reports Server (NTRS)

    Goldman, A. M., Jr.

    1980-01-01

    An experimental 20/30 GHz communications satellite conceptual design is described which employs multiple-beam paraboloid reflector antennas coupled to a TDMA transponder. It is shown that the satellite employs solid state GaAs FET power amplifiers and low noise amplifiers while signal processing and switching takes place on-board the spacecraft. The proposed areas to be served by this satellite would be the continental U.S. plus Alaska, Hawaii, Puerto Rico, and the Virgin Islands, as well as southern Canada and Mexico City. Finally, attention is given to the earth stations which are designed to be low cost.

  15. A True Metasurface Antenna

    PubMed Central

    Badawe, Mohamed El; Almoneef, Thamer S.; Ramahi, Omar M.

    2016-01-01

    We present a true metasurface antenna based on electrically-small resonators. The resonators are placed on a flat surface and connected to one feed point using corporate feed. Unlike conventional array antennas where the distance between adjacent antennas is half wavelength to reduce mutual coupling between adjacent antennas, here the distance between the radiating elements is electrically very small to affect good impedance matching of each resonator to its feed. A metasurface antenna measuring 1.2λ × 1.2λ and designed to operate at 3 GHz achieved a gain of 12 dBi. A prototype was fabricated and tested showing good agreement between numerical simulations and experimental results. Through numerical simulation, we show that the metasurface antenna has the ability to provide beam steering by phasing all the resonators appropriately. PMID:26759177

  16. Low-Profile UHF Antenna Design Based on an Anisotropic Transverse Resonance Condition

    DTIC Science & Technology

    2014-08-01

    MHz, which makes them unsuitable as substrates for UHF antenna structures. The availability of artificial magnetic metamaterials has widened the...Furthermore, the development of artificial magnetic metamaterials allows engineers to separately control the values of both magnetic permeability and...conditions with the conducting walls of the cavity. Furthermore, this report demonstrates that using anisotropic magnetic metamaterials to load this

  17. Airborne antenna pattern calculations

    NASA Technical Reports Server (NTRS)

    Bagherian, A. B.; Mielke, R. R.

    1983-01-01

    Use of calculation program START and modeling program P 3D to produce radiation patterns of antennas mounted on a space station is discussed. Basic components of two space stations in the early design stage are simulated and radiation patterns for antennas mounted on the modules are presented.

  18. Bidirectional zoom antenna

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1975-01-01

    Antenna comprises two parabolic cylinders placed orthogoanlly to each other. One cylinder serves as main reflector, and the other as subreflector. Cylinders have telescoping sections to vary antenna beamwidth. Beamwidth can be adjusted in elevation, azimuth, or both. Design has no restriction as to choice of polarization.

  19. Surge current and electron swarm tunnel tests of thermal blanket and ground strap materials

    NASA Technical Reports Server (NTRS)

    Hoffmaster, D. K.; Inouye, G. T.; Sellen, J. M., Jr.

    1977-01-01

    The results are described of a series of current conduction tests with a thermal control blanket to which grounding straps have been attached. The material and the ground strap attachment procedure are described. The current conduction tests consisted of a surge current examination of the ground strap and a dilute flow, energetic electron deposition and transport through the bulk of the insulating film of this thermal blanket material. Both of these test procedures were used previously with thermal control blanket materials.

  20. The JPL mechanically steered antenna

    NASA Technical Reports Server (NTRS)

    Berner, Jeff B.; Bell, David J.

    1988-01-01

    The Jet Propulsion Laboratory has designed and developed a mechanically steered antenna for tracking satellites in a mobile environment. This antenna was used to track an L-band beacon on the MARISAT satellite. A description of the antenna and the results of the satellite experiment are given.