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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. 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.

  3. Upgrades to the 4-strap ICRF antenna in Alcator C-Mod

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

    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 2/2000, 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 7/2000, with the installation of BN plasma-facing tiles and radiofrequency 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 2/2001 and will be completed by this meeting. All the above upgrades and their effect on antenna performance will be presented.

  4. 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.

  5. Analysis of 4-strap ICRF Antenna Performance in Alcator C-Mod

    SciTech Connect

    G. Schilling; S.J. Wukitch; R.L. Boivin; J.A. Goetz; J.C. Hosea; J.H. Irby; Y. Lin; A. Parisot; M. Porkolab; J.R. Wilson; the Alcator C-Mod Team

    2003-07-31

    A 4-strap ICRF antenna was designed and fabricated for plasma heating and current drive in the Alcator C-Mod tokamak. Initial upgrades were carried out in 2000 and 2001, which eliminated surface arcing between the metallic protection tiles and reduced plasma-wall interactions at the antenna front surface. A boron nitride septum was added at the antenna midplane to intersect electric fields resulting from radio-frequency sheath rectification, which eliminated antenna corner heating at high power levels. The current feeds to the radiating straps were reoriented from an E||B to E parallel B geometry, avoiding the empirically observed {approx}15 kV/cm field limit and raising antenna voltage holding capability. Further modifications were carried out in 2002 and 2003. These included changes to the antenna current strap, the boron nitride tile mounting geometry, and shielding the BN-metal interface from the plasma. The antenna heating efficiency, power, and voltage characteristics under these various configurations will be presented.

  6. 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).

  7. 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.

  8. The IGNITOR ICRH Antenna Design with TOPICA

    NASA Astrophysics Data System (ADS)

    Maggiora, Riccardo; Kyrytsya, Volodymyr; Milanesio, Daniele; Meneghini, Orso; Vecchi, Giuseppe

    2007-11-01

    A flexible auxiliary Ion Cyclotron Resonance Heating (ICRH) system (f = 80 -- 120 MHz) has been included in the IGNITOR machine design. ICRH systems have been successfully tested on a number of existing devices especially at high density. Ignition can be accelerated significantly by relatively low levels of ICRH (about 5 MW, a fraction of the final fusion heating) when applied during the current ramp-up. In addition, ICRH provides a useful tool to control the evolution of the current density profile. Four antennas, each composed by 4 straps independently fed by 4 matching systems, can deliver a minimum RF power of about 12 MW in the entire adopted frequency range. The possibility of adding two more antennas has been considered. The antenna design and optimization have been based on the simulation results obtained with TOPICA (Torino Polytechnic Ion Cyclotron Antenna code)[1]. [1] V. Lancellotti et al., Nuclear Fusion, 46 (2006) S476-S499

  9. The ITER ICRF Antenna Design with TOPICA

    NASA Astrophysics Data System (ADS)

    Milanesio, Daniele; Maggiora, Riccardo; Meneghini, Orso; Vecchi, Giuseppe

    2007-11-01

    TOPICA (Torino Polytechnic Ion Cyclotron Antenna) code is an innovative tool for the 3D/1D simulation of Ion Cyclotron Radio Frequency (ICRF), i.e. accounting for antennas in a realistic 3D geometry and with an accurate 1D plasma model [1]. The TOPICA code has been deeply parallelized and has been already proved to be a reliable tool for antennas design and performance prediction. A detailed analysis of the 24 straps ITER ICRF antenna geometry has been carried out, underlining the strong dependence and asymmetries of the antenna input parameters due to the ITER plasma response. We optimized the antenna array geometry dimensions to maximize loading, lower mutual couplings and mitigate sheath effects. The calculated antenna input impedance matrices are TOPICA results of a paramount importance for the tuning and matching system design. Electric field distributions have been also calculated and they are used as the main input for the power flux estimation tool. The designed optimized antenna is capable of coupling 20 MW of power to plasma in the 40 -- 55 MHz frequency range with a maximum voltage of 45 kV in the feeding coaxial cables. [1] V. Lancellotti et al., Nuclear Fusion, 46 (2006) S476-S499

  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. GPS antenna designs

    NASA Astrophysics Data System (ADS)

    Laube, Samuel J. P.

    1987-05-01

    Application of the current GPS NAVSTAR system to civilian service requires that a right hand, circularly polarized, -160 dBW spread spectrum signal be received from an orbiting satellite, where the antenna environment is also moving. This presents a design challenge when inexpensive antennas are desired. The intent of this survey is to provide information on the antennas mentioned and to construct and test prototypes to determine whether the choice made by the industry, the quadrifilar helix, is the best. The helix antenna is currently the low cost standard for GPS. Prototype versions were constructed using 12 gauge wire and subminiature coaxial hardline. The constructed antennas were tested using a signal generator and a reference turnstile. A spectrum analyzer was used to measure the level of the received signal.

  12. GPS antenna designs

    NASA Technical Reports Server (NTRS)

    Laube, Samuel J. P.

    1987-01-01

    Application of the current GPS NAVSTAR system to civilian service requires that a right hand, circularly polarized, -160 dBW spread spectrum signal be received from an orbiting satellite, where the antenna environment is also moving. This presents a design challenge when inexpensive antennas are desired. The intent of this survey is to provide information on the antennas mentioned and to construct and test prototypes to determine whether the choice made by the industry, the quadrifilar helix, is the best. The helix antenna is currently the low cost standard for GPS. Prototype versions were constructed using 12 gauge wire and subminiature coaxial hardline. The constructed antennas were tested using a signal generator and a reference turnstile. A spectrum analyzer was used to measure the level of the received signal.

  13. Antenna theory and design

    NASA Astrophysics Data System (ADS)

    Stutzman, W. L.; Thiele, G. A.

    Antenna fundamentals and definitions are examined, taking into account electromagnetic fundamentals, the solution of Maxwell's equations for radiation problems, the ideal dipole, the radiation pattern, directivity and gain, reciprocity and antenna pattern measurements, antenna impedance and radiation efficiency, antenna polarization, antennas in communication links and radar, and the receiving properties of antennas. Some simple radiating systems are considered along with arrays, line sources, wire antennas, broadband antennas, moment methods, and aperture antennas. High-frequency methods and aspects of antenna synthesis are discussed, giving attention to geometrical optics, physical optics, wedge diffraction theory, the ray-fixed coordinate system, the cylindrical parabolic antenna, and linear array methods.

  14. Designing the IShTAR antenna: Physics and engineering aspects

    NASA Astrophysics Data System (ADS)

    Louche, F.; Jacquot, J.; Crombé, K.; Van Eester, D.; D'Inca, R.; Devaux, S.; Faudot, E.; Faugel, H.; Fünfgelder, H.; Heuraux, S.; Morgal, I.; Moritz, J.; Ochoukov, R.; Noterdaeme, J.-M.

    2015-12-01

    IShTAR (Ion cyclotron Sheath Test ARrangement) is a magnetised plasma test facility installed at the Max-Planck-Institut für Plasmaphysik in Garching, Germany. The main purpose of this device is the study of RF sheaths generated in front of ICRF (Ion Cyclotron Range of Frequency) antennas in magnetically confined plasmas. The plasma is generated by a helical RF antenna potentially able to reach a helicon mode. We present in this work recent modelling activities dedicated to IShTAR. On the one hand a parameterized magnetostatic model of the magnetic configuration was created with the finite element solver COMSOL Multiphysics [3]. The model considers two non-axial sets of coils and notably reproduces the magnetic field lines deviation at the center of the main vessel and the ripples observed during experiments. From this model we can infer that kA are required in the 2 main large coils of IShTAR for 1 kA in the 4 small coils to generate a "smooth" magnetic field along field lines. On the other hand an ICRF antenna has been designed for IShTAR. A tridimensional model of the IShTAR vessel was developed with the electromagnetic code MicroWave Studio (MWS [4]) for this purpose and a first antenna model made of a single strap inside a box was included. The strap is fed through the upper port located at the helicon source side. The antenna is fully immersed into the loading medium (plasma or homogeneous dielectric) and the curved strap front face is aligned with the magnetic surfaces to simplify the modelling. The initial design of this antenna has been studied with MWS in the presence of homogeneous dielectric. The presence of a back wall will be discussed.

  15. 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.

  16. Resonant loop antenna design with a 2-D steady state analysis

    SciTech Connect

    Chen, G.I.; Ryan, P.M.; Hoffman, D.J.; Baity, F.W.; Swain, D.W.; Whealton, J.H.

    1987-01-01

    Evaluation of resonant loop antenna designs for ICRF heating of plasmas requires information concerning the electrical characteristics of the structure. Our 2-D steady state model described herein provides us with current strap inductance and capacitance, surface current distributions, and flux linkage to the plasma. These are used to determine the current and voltage requirements, ohmic dissipation, frequency limits and matching requirements, maximum electric fields, and plasma loading in order to compare antenna designs.

  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. 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.

  19. Microstrip antenna theory and design

    NASA Astrophysics Data System (ADS)

    James, J. R.; Hall, P. S.; Wood, C.

    Microstrip is the name given to a type of open waveguiding structure which is now commonly used in present-day electronics, not only as a transmission line but for circuit components such as filters, couplers, and resonators. The idea of using microstrip to construct antennas is a much more recent development. The purpose of this monograph is to present the reader with an appreciation of useful antenna design approaches and the overall state-of-the art situation. Flat-plate antenna techniques and constraints on performance are considered along with microstrip design equations and data, the radiation mechanism of an open-circuit microstrip termination and the resulting design implications, the basic methods of calculation and design of patch antennas, and linear array techniques. Attention is also given to techniques and design limitations in two-dimensional arrays, circular polarization techniques, manufacturing and operational problems of microstrip antennas, recent advances in microstrip antenna analysis, and possible future developments.

  20. 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.

  1. COBRA meteor radar antenna designs

    NASA Astrophysics Data System (ADS)

    Zainuddin, Mohamad

    A meteor radar system is one of the effective remote sensing techniques in measuring atmospheric parameters such as wind velocities, temperature, pressure and density which are essential in understanding the atmospheric dynamics in the Mesosphere Lower Thermosphere (MLT) region. Previous studies of very high frequency (VHF) meteors radar systems suggest that the minimum error for the estimation of the horizontal wind velocity from a radar interferometry algorithm should occur when the main beams of the transmit and receive antennas are pointing to between 30° to 50° elevation angles. Therefore, an ideal antenna design for VHF meteor radar systems would produce a pencil beam radiation pattern at a 45° elevation angle. However, both the transmit and receive antenna of the COBRA meteor radar system have major beams are pointing to between 60° to 65° degree elevation angles above a perfect ground plane. Besides transmitting maximum power at low elevation angles, the current antennas of the COBRA meteor radar are highly dependent on the ground plane to radiate maximum gains to between 60° to 65° degree elevation angles. Typically, the earth ground is considered as a common ground plane for many VHF antenna with acceptable performance. However, the earth ground could not effectively reflect most of the power at all time. Because the antennas are dependent on ground to radiate power at certain direction, an artificial ground plane or ground screen has to be built for the COBRA antenna system at the South Pole station, which is located on top of more than 2000 meter thick of ice sheet. This dissertation focuses on the analysis of the performance of the individual current antenna design with four different conditions namely in free space, above an infinite ground, lossy ground and finite ground. In the analysis of finite ground, the effects of varying wire spacing and the size of finite ground to the radiation pattern of a cross folded dipole antenna are investigated

  2. Designing Rectangular RHCP Microstrip Antennas

    NASA Technical Reports Server (NTRS)

    Davidson, Shayla E.

    1987-01-01

    RHCP, Right-Handed, Circularly Polarized Microstrip Antenna program, aids in design of rectangular microstrip-antenna element, given desired frequency of operation and characteristics of substrate. Begins design calculations on basis of square element with linear polarization. Effective dielectric constant and changes in electrical length due to fringing at edges of radiating element taken into account. Coaxial feed inset with 50 ohms input impedance. Placement of feed such that two orthonormal modes produced in antenna cavity, right- or left-handed circular polarization obtained. Written in FORTRAN 77.

  3. Design aspects of commercial satellite antennas

    NASA Astrophysics Data System (ADS)

    Lang, K. C.; Taormina, F. A.

    General design considerations for commercial satellite antennas are reviewed, and design factors of shaped beam reflector antennas are described, including shaped beam efficiency, flat-topping and boundary matching, and analysis by Fourier transforms. Attention is then given to the design of the Telesat Anik 17/Westar/Palapa communications antenna, the Comstar I communications antenna, the SBS communications antenna, and Intelsat IV A communications antenna.

  4. 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.

  5. Adaptive antenna design considerations for satellite communication antennas

    NASA Astrophysics Data System (ADS)

    Mayhan, J. T.

    1983-02-01

    The present investigation is concerned with some general considerations inherent in designing an adaptive antenna system for use on a geosynchronous satellite illuminating the earth field of view. The problem has been addressed from the viewpoint of the system designer who has to determine the required antenna characteristics and the antenna aperture size. Concerning the choice of the antenna type, it usually has to be decided whether to use a phased array (PA) or a multiple-beam antenna (MBA). Attention is given to nulling resolution and MBA/PA configuration, taking into account the phased array and multiple-beam antennas. The choice of which antenna type to use depends on the nulling bandwidth, the number of weighted channels in the adaptive processor, and the overall coverage area to be served by the antenna system.

  6. 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.

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

    SciTech Connect

    Ryan, P. M.; Baity, F. W.; Caughman, J. B. O.; Goulding, R. H.; Rasmussen, D. A.; Hosea, J. C.; Greenough, N. L.; Nagy, A.; Pinsker, R. I.

    2009-11-26

    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.

  8. 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.

  9. Mechanical design proposal of an Ions Cyclotron Resonant Heating antenna for ITER

    SciTech Connect

    Agarici, G.; Argouarch, A.; Brun, C.; Mitteau, R.; Mollard, P.; Patterlini, J. C.; Vulliez, K.; Testoni, P.; Maggiora, R.; Milanesio, D.

    2007-09-28

    The antenna design proposed here is based on the resonant double loop concept with conjugate T matching to make the circuit resilient to strong plasma load variations as ELMs. The antenna is constituted of two main parts; the in-vessel launcher which is inside the primary torus vacuum and the Compact Vacuum Tuners (CVT) that is located after the first barrier in a private vacuum. This CVT allows to match at the strap location, the antenna impedance with the plasma load, over the 45 to 55 MHz frequency range. It has been designed to ease its repair and maintenance, and can be easily removed from the rear without breaking the primary vacuum. Apart from the Faradays screens fit to shape the plasma edge, the in-vessel launcher and CVT are made out of 6 identical modules, to allow the best economical approach for the manufacture, the assembly and the maintenance of the antenna.

  10. Design of a High Power Prototype for the new JET-EP ICRF antenna

    NASA Astrophysics Data System (ADS)

    Goulding, R. H.; Baity, F. W.; Jones, G. H.; Nelson, B. E.; Rasmussen, D. A.; Swain, D. W.; Hosea, J. C.; Loesser, G. D.; Wilson, J. R.; Durodie, F.; Beaumont, B.; Lamalle, P. U.; Walton, R.

    2001-10-01

    A high power prototype (HPP) of a new ICRF antenna for JET ("JET-EP antenna") is being designed and constructed in a collaborative effort between Oak Ridge National Laboratory, Princeton Plasma Physics Laboratory, and the European Fusion Development Agreement-Joint European Torus. The JET-EP launcher is designed for 8 MW input power ( 9 MW/m^2) at 30-55 MHz. Current straps are arranged in a 4 poloidal by 2 toroidal array, minimizing voltage. A modified resonant double loop (RDL) matching circuit uses internal capacitors, and passively accommodates rapidly changing plasma loads. The HPP, consisting of one antenna quadrant, will be tested at ORNL in vaccum at >= 33kV pk, 920A rms capacitor voltage and current. Innovative features to be tested include the modified RDL circuit, flanges which allow capacitor replacement without antenna removal, a low characteristic impedance vacuum feed line, and integral matching transformer.

  11. 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.

  12. Automated Antenna Design with Evolutionary Algorithms

    NASA Technical Reports Server (NTRS)

    Linden, Derek; Hornby, Greg; Lohn, Jason; Globus, Al; Krishunkumor, K.

    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

  13. Design of broadband single polarized antenna

    NASA Astrophysics Data System (ADS)

    Shin, Phoo Kho; Aziz, Mohamad Zoinol Abidin Abd.; Ahmad, Badrul Hisham; Ramli, Mohamad Hafize Bin; Fauzi, Noor Azamiah Md; Malek, Mohd Fareq Abd

    2015-05-01

    In practical wireless communication application, bandwidth enhancement becomes one of the major design considerations. At the same time, circular polarized (CP) antenna received much attention for the applications of modern wireless communication system when compared to linear polarized (LP) antenna. This is because CP antenna can reduce the multipath effect. Hence, broadband antenna with operating frequency at 2.4GHz for WLAN application is proposed. The proposed antenna is done by using L-probe amendment with rectangular patch. The rectangular patch and copper ground plane is separated with 10mm air gap. This approach is used to enhance the bandwidth and the gain of the proposed antenna. The bandwidth of the designed antenna is more than 200MHz which meet broadband application. The return loss for the antenna is below -10dB to achieved 90% matching efficiency. The position of L-probe feed is altered in order to obtained different polarizations. The broadband antenna had been designed and simulated by using Computer Simulation Technology (CST) software. In this paper, the comparison for single polarized antenna with the design of non-inverted patch and inverted patch is discussed. The characteristics of the S-parameter, axial ratio, gain, surface current for each designed antenna are analyzed.

  14. Microfluidic serpentine antennas with designed mechanical tunability.

    PubMed

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

    2014-11-01

    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%. PMID:25144304

  15. 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.

  16. Lower Hybrid Antenna Design for MST

    SciTech Connect

    Goetz, J.A.; Thomas, M.A.; Kaufman, M.C.; Oliva, S.P.

    2005-09-26

    Inter-digital line antennas are being used to test the feasibility of lower hybrid current drive in MST. The antennas use {lambda}/4 resonators and launch slow waves at 800 MHz with n parallel {approx} 7.5. Routine operation has been achieved with a good impedance match between antenna and plasma. High power antenna design improvements include larger vacuum feed-throughs, better impedance matching, and rf instrumentation on all resonators. The antenna and feed-through modeling was performed with CST Microwave Studio{sup TM}. The pulse-forming network that powers the klystron is being upgraded to a 50 kV - 30 ms pulse. The goal for the LHCD system on MST is a modular design that can handle 300 kW per antenna.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Antenna design and characterization based on the elementary antenna concept

    NASA Astrophysics Data System (ADS)

    Ligthart, L. P.

    An antenna-design technique based on an elementary-antenna model (an infinitesimal pillbox structure carrying electric and magnetic currents and containing propagating TEM fields) is developed and demonstrated. An EM description of a waveguide aperture is obtained by applying approximate boundary conditions at specific points; the transmitted field is developed locally into a set of TEM field components to compute the radiation pattern; and aperture matching is achieved by calculating the aperture reflection as well. Parallel-plate, circular, and rectangular waveguides; two single-polarization TEM waveguide radiators (with and without dielectric filling); a dielectric-filled dual-polarization TE(01) waveguide radiator; and a hybrid reflector array with limited beam switching based on the TE(01) radiator are presented.

  3. Design considerations for MST radar antennas

    NASA Technical Reports Server (NTRS)

    Bowhill, S. A.

    1983-01-01

    The design of antenna systems for radar capable of probing the mesosphere are discussed. The spatial wavelength dependency of turbulent advected ionization are cut off rapidly below wavelengths of about 3 m, imply frequencies of 100 MHz and below. The frequency and aperture requirements point to an array antenna of some kind as the most economical solution. Such an array could consist of dipoles or more directive elements; these elements can be either active or passive.

  4. Design of microstrip disk antenna arrays

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.; Parks, F. G.

    1978-01-01

    The radio frequency characteristics and design parameters for microstrip disk antenna elements and planar arrays are presented. Two C-band model arrays (an 8 element linear and an 8 by 8 planar) were designed, fabricated, and tested to demonstrate the technique of using microstrip elements for array applications. These arrays were designed with a cosine amplitude distribution.

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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.

  11. Compact acoustic antenna design using labyrinthine metamaterials

    NASA Astrophysics Data System (ADS)

    Ren, Chunyu

    2015-05-01

    We present an effective design and architecture for a class of acoustic antennas in air. The work begins with a conformal transformation method that yields the preliminary design, which is constructed using an isotropic but inhomogeneous material. However, the desired material parameters have been unavailable until now. Here we show that by scaling up the refractive index and optimizing the geometry in the preliminary design, a series of square antennas can be achieved to exhibit an excellent beam-collimating effect. An important part of our strategy is that the device's thickness and material properties can be tailored easily to greatly facilitate its realization. It is also demonstrated that the proposed antenna can be made very thin and readily implemented using labyrinthine acoustic metamaterials.

  12. Optimization of the ITER Ion Cyclotron Heating Antenna Array

    NASA Astrophysics Data System (ADS)

    Ryan, P. M.; Swain, D. W.; Carter, M. D.; Taylor, D. J.; Bosia, G.; D'Ippolito, D. A.; Myra, J. R.

    1996-11-01

    The present design of the ITER ICH antenna array comprises two poloidal by four toroidal current elements in each of four ports. Each current element forms a resonant double loop (RDL) with power fed to a pretuned matchpoint on the strap; the matching is accomplished using slow-wave transmission lines as adjustable shorted-stub tuners on either end of the current strap. The power requirement is 12.5 MW per port over the frequency range of 40--70 MHz, with extended operation to 80 MHz desirable. The antenna design optimization process includes strap shaping to minimize strap voltages and rf E-fields along B-field lines, (2) frame/Faraday shield geometry design to improve plasma coupling, wave spectrum directivity, and phase control, and (3) Faraday shield/bumper geometry to minimize rf sheath-induced structure heating and impurity generation.

  13. 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.

  14. 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.

  15. 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

  16. OCH Strap Model Test

    SciTech Connect

    Weber, K.; /Fermilab

    1987-08-26

    The OCH Model was stacked using the appropriate spacers between each absorber plate. Steel bars measuring 3-inch wide by 1/4-inch thick were welded, using 1/8-inch fillet weld, along all the corner edges, except the outer radius edges. On the outer radius, the straps were bolted to the end plates and to plates 9 and 17. The straps on the outer radius were also set in towards the center by approximately 3-inches. The spacers were then knocked out. Twelve strain gauges were mounted on the model. See figure 1 and the OCH strap Model log book for locations. Each rosette was centered in the gap between two absorber plates. The finite element plate model can predict the primary deformations of the OH module in both the cantilever and crushing modes to within 11% of the measured values. The primary stresses away from the support plate for the cantilever mode can be predicted to within 13% by this model. Near the support plate where large shear stresses exists, ANSYS will overpredict the measured stresses substantially. This is probably due to the models inherent inability to allow for shear stress concentrations at the welds. The same over-prediction was seen in the side straps during the OH crush test comparison and is probably attributable to the high shear force in this mode. The simple finite element plate model will provide suitable model of OH module stiffness for use in the analysis of the module assembly. The calculation of shear stresses can be improved by applying the ANSYS calculated inter-element forces to traditional weld strength calculations

  17. 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.

  18. 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.

  19. Using EIGER for Antenna Design and Analysis

    NASA Technical Reports Server (NTRS)

    Champagne, Nathan J.; Khayat, Michael; Kennedy, Timothy F.; Fink, Patrick W.

    2007-01-01

    EIGER (Electromagnetic Interactions GenERalized) is a frequency-domain electromagnetics software package that is built upon a flexible framework, designed using object-oriented techniques. The analysis methods used include moment method solutions of integral equations, finite element solutions of partial differential equations, and combinations thereof. The framework design permits new analysis techniques (boundary conditions, Green#s functions, etc.) to be added to the software suite with a sensible effort. The code has been designed to execute (in serial or parallel) on a wide variety of platforms from Intel-based PCs and Unix-based workstations. Recently, new potential integration scheme s that avoid singularity extraction techniques have been added for integral equation analysis. These new integration schemes are required for facilitating the use of higher-order elements and basis functions. Higher-order elements are better able to model geometrical curvature using fewer elements than when using linear elements. Higher-order basis functions are beneficial for simulating structures with rapidly varying fields or currents. Results presented here will demonstrate curren t and future capabilities of EIGER with respect to analysis of installed antenna system performance in support of NASA#s mission of exploration. Examples include antenna coupling within an enclosed environment and antenna analysis on electrically large manned space vehicles.

  20. Advanced ICRF antenna design for R-TOKAMAK

    NASA Astrophysics Data System (ADS)

    Kako, E.; Ando, R.; Ichimura, M.; Ogawa, Y.; Amano, T.; Watari, T.

    1986-01-01

    The advanced ICRF antennas designed for the R-TOKAMAK (a proposal in the Institute of Plasma Physics, Nagoya University) are described. They are a standard loop antenna and a panel heater antenna for fast wave heating, and a waveguide antenna for ion Bernstein wave heating. The standard loop antenna is made of Al-alloy and has a simple structure to install because of radioactivation by D-T neutrons. For high power heating, a new type antenna called Panel heater antenna is proposed. It has a wide radiation area and is able to select a parallel wave number k. The field pattern of the panel heater antenna is measured. The feasibility of the waveguide antenna is discussed for ion Bernstein wave heating. The radiation from the aperture of the double ridge waveguide is experimentally estimated with a load simulating the plasma.

  1. Design of a new broadband monopole optical nano-antenna

    NASA Astrophysics Data System (ADS)

    Zhou, Rongguo; Ding, Jun; Arigong, Bayaner; Lin, Yuankun; Zhang, Hualiang

    2013-11-01

    In this paper, we propose a novel design of broadband monopole optical nano-antennas. It is consisted of a corrugated half elliptical patch inside an elliptical aperture. By adjusting the dimensions of the elliptical patch and the elliptical aperture, the overall performance of the proposed monopole nano-antenna can be made remarkable broadband. Full wave electromagnetic simulations have been used to investigate the effects of different parameters on the nano-antenna performance. Moreover, the proposed broadband nano-antenna can support light waves with different polarizations. It is expected that the new optical antenna will pave the way towards the development of high performance optical antennas and optical systems.

  2. 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.

  3. Factors in the design of adaptive antennas

    NASA Astrophysics Data System (ADS)

    Barton, P.

    A brief review of adaptive antenna technology is given, and two topic areas are addressed. The first is concerned with the general difficulties encountered in design, in particular the avoidance of nulling wanted signals, the provision of an adequate rate of convergence towards a desired characteristic, and the degradation of null depths caused by the proximity of the platform and by dispersion in the array and receiving channels. The second topic concerns specific design approaches. Closed loop processors, in which the array output is sensed in order to provide a drive to the weight networks, are exemplified by a feedback loop correlator design and a weight perturbation technique. An example of open-loop control of weight values is also included, and its lack of self-correction is shown to be disadvantageous compared to the closed loop approach. Advanced methods, associated with sample matrix inversion, are also summarized.

  4. 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.

  5. Electromagnetic design of a microwave radiometer antenna system

    NASA Technical Reports Server (NTRS)

    Agrawal, P. K.; Cockrell, C. R.

    1981-01-01

    A preliminary electromagnetic (EM) design of a radiometric antenna system was developed for the microwave radiometer spacecraft mission. The antenna system consists of a large spherical reflector and an array of feed horns along a concentric circular arc in front of the reflector. The reflector antenna was sized to simultaneously produce 200 contiguous 1 km diameter footprints with an overall beam efficiency of 90 percent, and the feed horns and feed horn array were designed to monitor the radiation from the footprints.

  6. 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.

  7. TOPICA: an accurate and efficient numerical tool for analysis and design of ICRF antennas

    NASA Astrophysics Data System (ADS)

    Lancellotti, V.; Milanesio, D.; Maggiora, R.; Vecchi, G.; Kyrytsya, V.

    2006-07-01

    The demand for a predictive tool to help in designing ion-cyclotron radio frequency (ICRF) antenna systems for today's fusion experiments has driven the development of codes such as ICANT, RANT3D, and the early development of TOPICA (TOrino Polytechnic Ion Cyclotron Antenna) code. This paper describes the substantive evolution of TOPICA formulation and implementation that presently allow it to handle the actual geometry of ICRF antennas (with curved, solid straps, a general-shape housing, Faraday screen, etc) as well as an accurate plasma description, accounting for density and temperature profiles and finite Larmor radius effects. The antenna is assumed to be housed in a recess-like enclosure. Both goals have been attained by formally separating the problem into two parts: the vacuum region around the antenna and the plasma region inside the toroidal chamber. Field continuity and boundary conditions allow formulating of a set of two coupled integral equations for the unknown equivalent (current) sources; then the equations are reduced to a linear system by a method of moments solution scheme employing 2D finite elements defined over a 3D non-planar surface triangular-cell mesh. In the vacuum region calculations are done in the spatial (configuration) domain, whereas in the plasma region a spectral (wavenumber) representation of fields and currents is adopted, thus permitting a description of the plasma by a surface impedance matrix. Owing to this approach, any plasma model can be used in principle, and at present the FELICE code has been employed. The natural outcomes of TOPICA are the induced currents on the conductors (antenna, housing, etc) and the electric field in front of the plasma, whence the antenna circuit parameters (impedance/scattering matrices), the radiated power and the fields (at locations other than the chamber aperture) are then obtained. An accurate model of the feeding coaxial lines is also included. The theoretical model and its TOPICA

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. The CS-2 satellite antenna design and characteristics

    NASA Astrophysics Data System (ADS)

    Misawa, M.; Watanabe, M.; Kumazawa, H.; Ueno, K.

    A satellite antenna has been studied for use in the Japanese domestic satellite communication system. In the electrical design, various design parameters were evaluated to estimate their effects on electrical performance in order to establish a shaped beam antenna covering the 4 GHz to 30 GHz band. In thermal and structural aspects, the design method based on analyses was verified by confirming the mechanical properties in enviromental tests. After a series of tests, it was confirmed that the antenna satisfied all the characteristics required for space use.

  15. Inductive antenna stent: design, fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Rashidi Mohammadi, Abdolreza; Ali, Mohamed Sultan Mohamed; Lappin, Derry; Schlosser, Colin; Takahata, Kenichi

    2013-02-01

    This paper describes the design, fabrication, and electromechanical characteristics of inductive stents developed for intelligent stent applications. The stents, fabricated out of 316L stainless-steel tubes using laser machining, are patterned to have zigzag loops without bridge struts, and when expanded, become a helix-like structure. Highly conductive metals such as copper and gold are coated on the stents to improve their inductive/antenna function. The Q-factor of the stent is shown to increase by a factor of 7 at 150 MHz with copper coating. The expansion of the stent from 2 to 4 mm diameter results in a 3.2× increase in the inductance, obtaining ˜1 µH at a similar frequency. The stent passivated by Parylene-C film is used to characterize its resonance in different media including saline. The copper-coated inductive stent exhibits a 2.4× radial stiffness for 1 mm strain as well as a 16× bending compliance compared with a commercial stent, each of which is potentially beneficial in preventing/mitigating stent failures such as recoil as well as enabling easier navigation through intricate blood vessels. The mechanical stiffness may be tailored by adjusting stent-wire thickness while maintaining necessary coating thickness to achieve particular mechanical requirements and high inductive performance simultaneously.

  16. Electrical optimization of the ICH antenna array for ITER

    NASA Astrophysics Data System (ADS)

    Ryan, P. M.; Swain, D. W.; Carter, M. D.; Taylor, D. J.; Bosia, G.

    1997-04-01

    The present design of the ITER ICH antenna array comprises two poloidal by four toroidal current elements in each of four ports. Each current element forms a resonant double loop (RDL) with power fed to a pretuned matchpoint on the strap; the matching is accomplished using slow-wave transmission lines as adjustable shorted-stub tuners on other end of the current strap. The power requirement is 12.5 MW per port over the frequency range of 40-70 MHz, with extended operation to 80 MHz desirable. The antenna design optimization process includes (1) strap shaping to minimize strap voltages and rf E-fields along B-field lines and (2) frame/Faraday shield geometry design to improve plasma coupling, wave spectrum directivity, and phase control. For the ignited plasma parameters, the optimized array design delivers full power over the ranges of 40-80 MHz in frequency and 0° to 180° in phase. The maximum strap voltage is 41 kV and the maximum parallel E-field is 16 kV/cm for the worst case over these ranges. The array directivity for current drive operation is calculated to be close to 80%.

  17. Antenna design for the Inmarsat second generation communication satellites

    NASA Astrophysics Data System (ADS)

    Huang, C. C.; McDonach, C. A.

    1990-02-01

    The Inmarsat satellite system provides international marine communications. This paper presents the RF design of a family of three antennas giving global coverage for the second generation of Inmarsat spacecraft. The antennas are direct radiating arrays operating at L-band and C-band with circular polarization. A very stringent low profile requirement is achieved by the use of cup-dipole radiators and integrated feed technology. The design of the cup-dipole is presented in detail together with the trade-offs leading to its selection as the radiating element. The measured antenna performance for all three arrays is presented showing good agreement with theoretical predictions.

  18. Tri-band microstrip antenna design for wireless communication applications

    NASA Astrophysics Data System (ADS)

    Sami, Gehan; Mohanna, Mahmoud; Rabeh, Mohamed L.

    2013-06-01

    This paper introduces a novel rectangular tri-band patch antenna that is fabricated and measured for wireless communication systems. The introduced antenna is designed for WLAN and WiMAX applications. The desired tri-band operation was obtained by proper loading for a rectangular patch antenna using slots and shorting pins. The optimal location and dimension for the loaded elements were obtained with the aid of interfacing a Genetic Algorithm (GA) model with an Ansoft High Frequency Structural Simulator (HFSS). The results obtained from our simulated antenna show 5.8% impedance matching band width at 2.4 GHz, 3.7% at 3.5 GHz and 1.57% at 5.7 GHz. In addition, an equivalent circuit of the proposed antenna is introduced using the least square curve fitting optimization technique.

  19. 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

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

    NASA Astrophysics Data System (ADS)

    Durodié, F.; Dumortier, P.; Vrancken, M.; Messiaen, A.; Bamber, R.; Hancock, D.; Huygen, S.; Lockley, D.; Louche, F.; Maggiora, R.; Milanesio, D.; Nightingale, M. P. S.; Shannon, M.; Tigwell, P.; Van Schoor, M.; Vervier, M.; Wilson, D.; Winkler, K.

    2014-06-01

    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 RF

  1. A finite difference approach to microstrip antenna design

    SciTech Connect

    Barth, M.J.; Bevensee, R.M.; Pennock, S.T.

    1986-12-01

    Microstrip antennas have received increased attention in recent years, due to their size and cost advantages. Analysis of the microstrip structure has proved difficult due to the presence of the dielectric substrate, particularly for complex geometries. One possible approach to a solution is the use of a finite difference computer code to model a proposed microstrip antenna design. The models are easily constructed and altered, and code versions are available which allow input impedance or far-field patterns to be calculated. Results for some simple antenna geometries will be presented.

  2. 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.

  3. 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.

  4. Advanced design methodologies and novel applications of reflectarray antennas

    NASA Astrophysics Data System (ADS)

    Nayeri, Payam

    Reflectarray antennas combine the numerous advantages of printed antenna arrays and reflector antennas and create a hybrid high-gain antenna with a low-profile, low-mass, and diversified radiation performance. Reflectarrays are now emerging as the new generation of high-gain antennas for long-distance communications. In this dissertation, some advanced concepts demonstrating novel features of reflectarray antennas are presented. • First, various approaches for radiation analysis of reflectarray antennas are described and implemented. Numerical results are then presented for a variety of systems and the advantages, limitations, and accuracy of these approaches are discussed and compared with each other. • A broadband technique by using sub-wavelength elements is proposed and prototypes are fabricated and tested. This technique enables the reflectarray to achieve a significant bandwidth improvement with no additional cost. • Infrared reflectarrays antennas are studied for possible applications in concentrating solar power systems. Material losses, an important design issue at infrared frequencies, are investigated and reflectarrays consisted of dielectric resonant elements are proposed with low-loss features at infrared. • Multi-beam reflectarray antennas are studied and it is demonstrated that by optimizing the phase of the elements, a desirable multi-beam performance can be achieved using a single-feed. Local and global phase-only optimization techniques have been implemented. Two Ka-band quad-beam prototypes with symmetric and asymmetric beams have been fabricated and tested. • Different approaches for beam-scanning with reflectarray antennas are also reviewed and it is shown that for moderately wide angle beam-scanning, utilizing a feed displacement technique is more suitable than an aperture phase tuning approach. A feed displacement beam-scanning design with novel aperture phase distribution is proposed for the reflectarray antenna, and is further

  5. Design considerations for an archimedean slot spiral antenna

    NASA Technical Reports Server (NTRS)

    Nurnberger, Michael W.; Volakis, John L.

    1995-01-01

    The design goal is to develop a 118-157 MHz, vertically polarized, low-profile (or conformal) antenna as a replacement for VHF AM blade antennas on aircraft. This design is to be arrived at by scaling the dimensions of an antenna designed for a center frequency of 1.1 GHz. The design prior to scaling may have the following maximum dimensions: diameter less than 3.70 in. and thickness less than 0.50 in. Although a four-arm spiral design was originally suggested, a two-arm spiral may also be used, as both mode-1 and mode-2 (sum and difference) radiation patterns aren't required. While a four-arm spiral can easily be designed should both sum and difference patterns be required, the two-arm design will provide the required sum pattern and simplify the design problem somewhat: only one feed is required, and the feed area geometry is more straightforward. Polarization requirements dictate that a slot spiral be used, as opposed to a wire spiral. Two similar radiating structures were considered. The first is the standard archimedean spiral antenna. The second is a hollow archimedean spiral antenna, essentially a standard archimedean spiral with the inner portion removed.

  6. 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.

  7. 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

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

    PubMed

    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

  9. RHCP- DESIGNING RECTANGULAR RIGHT-HANDED CIRCULARLY POLARIZED MICROSTRIP ANTENNAS

    NASA Technical Reports Server (NTRS)

    Davidson, S. E.

    1994-01-01

    RHCP, the Right-Handed, Circularly Polarized Microstrip Antenna program, aids in the design of a rectangular antenna element, given the desired frequency of operation and substrate characteristics. RHCP begins the design calculations based on a square element with linear polarization. The effective dielectric constant and changes in electrical length due to fringing at the radiating element edges are taken into account. A coaxial feed is inset with 50 ohms input impedance. By placing the feed such that two orthonormal modes are produced in the antenna cavity, right- or left-handed circular polarization is obtained. Input to RHCP consists of desired frequency, dielectric constant, and substrate thickness. Output consists of the final rectangular geometry, the proposed feed inset placement, and actual input impedance. RHCP has been used successfully for frequencies between 2 and 15 GHz for thin substrates. This program was used to fabricate antenna elements for the S-band quad antennas on board the Space Shuttle, and is a part of the design project for the S-band phased array antenna radiating aperture. RHCP is written in FORTRAN 77 for interactive execution and has been implemented on a DEC VAX series computer operating under VMS. This program was developed in 1985.

  10. Benchmark simulations of ICRF antenna coupling

    NASA Astrophysics Data System (ADS)

    Louche, F.; Lamalle, P. U.; Messiaen, A. M.; Van Compernolle, B.; Milanesio, D.; Maggiora, R.

    2007-09-01

    The paper reports on ongoing benchmark numerical simulations of antenna input impedance parameters in the ion cyclotron range of frequencies with different coupling codes: CST Microwave Studio, TOPICA and ANTITER 2. In particular we study the validity of the approximation of a magnetized plasma slab by a dielectric medium of suitably chosen permittivity. Different antenna models are considered: a single-strap antenna, a 4-strap antenna and the 24-strap ITER antenna array. Whilst the diagonal impedances are mostly in good agreement, some differences between the mutual terms predicted by Microwave Studio and TOPICA have yet to be resolved.

  11. Benchmark simulations of ICRF antenna coupling

    SciTech Connect

    Louche, F.; Lamalle, P. U.; Messiaen, A. M.; Compernolle, B. van; Milanesio, D.; Maggiora, R.

    2007-09-28

    The paper reports on ongoing benchmark numerical simulations of antenna input impedance parameters in the ion cyclotron range of frequencies with different coupling codes: CST Microwave Studio, TOPICA and ANTITER 2. In particular we study the validity of the approximation of a magnetized plasma slab by a dielectric medium of suitably chosen permittivity. Different antenna models are considered: a single-strap antenna, a 4-strap antenna and the 24-strap ITER antenna array. Whilst the diagonal impedances are mostly in good agreement, some differences between the mutual terms predicted by Microwave Studio and TOPICA have yet to be resolved.

  12. Design and Fabrication of Carbon Nano-structured Flexible Antenna

    NASA Astrophysics Data System (ADS)

    Lamba, V. K.; Kumar, A.; Verma, M.; Dhariwal, S.; Sharma, K.; Anand, S.; Engles, D.

    2012-10-01

    With a development and an increasing interest in flexible electronics, for civil, medical, space, and military domains, we present a design of a patch antenna using CNT-polymer ink on fabrics. We have prepared CNT ink, and measured its properties to use as a conducting material for making patches. The antenna is designed on cotton and Songket fabric that resonates at 2.3GHz on a 1.23 mm, and 1.06 mm thick fabric substrate with ɛr ≍ 1.7, and ɛr ≍ 1.9 for cotton and Songket respectively. Measured and simulation results shows that band width depends on thickness and type of fabrics we used. All antenna parameters such as VSWR, return loss, gain and radiation pattern meet the design criteria.

  13. 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.

  14. Design of a Foldable Low-loss Microstrip Array Antenna

    NASA Technical Reports Server (NTRS)

    Christodoulou, C. G.; Wahid, P. F.; Haque, M. M.; Bailey, M. C.

    1999-01-01

    The design and analysis of a series-fed, foldable microstrip array antenna for radiometer applications is presented. The array antenna is composed of two equal sub arrays. Each sub array consists of a series of patches connected together through segments of microstrip lines. The sub arrays are fed 180 degree out of phase to ensure 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.

  15. Antenna servo design for tracking low-earth-orbiting satellites

    NASA Astrophysics Data System (ADS)

    Gawronski, W.; Mellstrom, J. A.

    1994-11-01

    The 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 paper 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, monopulse controller design, and tracking error reduction either through proper choice of elevation pinion location or through 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 oversampled monopulse signal is described.

  16. 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.

  17. Design and analysis of annular antenna arrays with different reflectors.

    PubMed

    Shi, G; Joines, W T

    2004-09-01

    The design and performance of annular antenna arrays with reflectors is presented. Arrays with three shapes of reflectors are analysed and simulated. These include the corner reflector, the circular reflector and the elliptical reflector. Power-density distributions within the annular arrays with and without reflectors are obtained by using the FDTD method. Also, the image theory method is used to verify the FDTD results in one case. By comparing the power-density distribution pattern of all four of the array designs (three with different reflectors, one without reflector), it is readily seen in each case that the array with reflectors yields better power-efficiency than the array without reflectors and the elliptical reflector yields the best performance. Comparisons of each array are made using 4, 6 and 8 antennae in the annular array. By using the optimized results of the elliptical reflector, the requirement for the input-power level to each antenna is greatly reduced. PMID:15370818

  18. 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.

  19. 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. PMID:25651405

  20. Mechanical design and evaluation of a slotted CFRP waveguide antenna

    NASA Astrophysics Data System (ADS)

    Knutsson, L.; Brunzell, S.; Magnusson, H.

    A development program for a slotted waveguide array antenna made of metallized CFRP was carried out. The main objective was to minimize the weight of the structure without degrading the electrical and mechanical performance. This paper focuses on mechanical design aspects and manufacturing methods of metallized CFRP waveguides and assembly of an antenna array. A weight saving of approximately 40 percent was accomplished by the CFRP structure compared to a corresponding aluminum structure. Electrical properties and cost were essentially equal for the two concepts.

  1. TOPLHA: an accurate and efficient numerical tool for analysis and design of LH antennas

    NASA Astrophysics Data System (ADS)

    Milanesio, D.; Lancellotti, V.; Meneghini, O.; Maggiora, R.; Vecchi, G.; Bilato, R.

    2007-09-01

    Auxiliary ICRF heating systems in tokamaks often involve large complex antennas, made up of several conducting straps hosted in distinct cavities that open towards the plasma. The same holds especially true in the LH regime, wherein the antennas are comprised of arrays of many phased waveguides. Upon observing that the various cavities or waveguides couple to each other only through the EM fields existing over the plasma-facing apertures, we self-consistently formulated the EM problem by a convenient set of multiple coupled integral equations. Subsequent application of the Method of Moments yields a highly sparse algebraic system; therefore formal inversion of the system matrix happens to be not so memory demanding, despite the number of unknowns may be quite large (typically 105 or so). The overall strategy has been implemented in an enhanced version of TOPICA (Torino Polytechnic Ion Cyclotron Antenna) and in a newly developed code named TOPLHA (Torino Polytechnic Lower Hybrid Antenna). Both are simulation and prediction tools for plasma facing antennas that incorporate commercial-grade 3D graphic interfaces along with an accurate description of the plasma. In this work we present the new proposed formulation along with examples of application to real life large LH antenna systems.

  2. Array antennas design in dependence of element-phasing

    NASA Astrophysics Data System (ADS)

    Zichner, R.; Chandra, M.

    2009-05-01

    Array antennas are used in science as well as for commercial and military purposes. The used element antennas act in accordance to their desired uses, for example radars or stationer GPS satellites. Typical components are for example slotted waveguides, patches, yagi-antennas and helix-antennas. All these elements do stand out with their own characteristics based on their special applications. If these elements are formed into an array configuration, the effectiveness can be improved immensely. There is a relation between the array functions and the physical array properties like the element alignment (linear, planar, circular), distances between the elements and so on. Among the physical properties there are other attributes like phase or amplitude coefficients, which are of great significance. The aim of this study was to provide an insight into the problem of array design, as far as the antenna element phase is concerned. Along with this, array radiation characteristics effects are presented. With the help of the extracted cognitions beam forming behaviour can be shown and the array phase behaviour can be analysed. One of the main applications is to simulate the array characteristics, like the radiation characteristic or the gain, for displacements of the array feeding point. A software solution that simulates the phase shift of a given array pattern is sought to adjust the feeding point.

  3. 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.

  4. 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.

  5. An alternative feed design for the MRO antenna

    NASA Technical Reports Server (NTRS)

    Imbriale, William A.

    2005-01-01

    NASA's Mars Reconnaissance Orbiter (MRO), scheduled for launch in 2005, will study the history of water on Mars. The current feed design for the 3-meter reflector antenna uses a dielectrically supported disk-on-rod Kaband (32 GHz) feed in the center of an X-band (7.2, 8.4 GHz) corrugated horn. As a potential backup design in case of problems, an alternate feed design for the MRO antenna that does not use any dielectric materials or a disc-on-rod was developed. The design uses a Ka-band Potter Horn in the center of the current Xband MRO corrugated horn. Using the same High-gain reflector assembly, the new feed provides virtually the same X-band gain (within 0.1 db) and more than 1 dB improvement at Ka-band.

  6. An experimental and analytical evaluation of the tapered tension-torsion strap concept

    NASA Technical Reports Server (NTRS)

    Louie, Alexander

    1988-01-01

    A new free-tip rotor moment controller designed to increase torque output (a restoring moment) was proposed. The controller would be used as a retention device for the freely pitching tip of a helicopter rotor. The new design featured a tapered tension-torsion strap instead of the previously used parellel strap. A tapered strap has a larger separation between the tension wires at the retention end than at the oscillating end; separation is equal at both ends for a parallel strap. A simple dynamic analysis was developed and an experiment performed to evaluate this tapered strap concept. The test results indicated that the torsional spring stiffness of the strap, represented by a torsional pendulum, increased with the amount of taper. The predicted dynamic characteristics of the pendulum also confirmed this observation and correlated reasonably well with the experimental results. It could be concluded from the experimental and analytical results that the tapered strap accomplished increased torque output when compared to the parellel strap.

  7. Method of making steel strapping and strip

    SciTech Connect

    Robert D. Reilly

    2000-02-16

    The technical progress obtained for this time frame consisted of the awarding of two contracts for determination of metallurgical parameters for heat treatment of strapping and strip which are unavailable from current technology and/or published data in this field. The two contractors were Bricmont, Inc. and the Department of Materials Science and Engineering at the Technological Institute of Northwestern University, Evanston, IL. Phase 1 of the two stage contract with Bricmont, Inc. which provided a computer analysis of the cooling rates of a typical range of thickness' of strapping was completed. This study was developed for the purpose of determining the time parameters for quenching low carbon steels to a martensitic microstructure within the time frame of the design of the proposed process. It also provides design criteria for cooling to ambient for the total process. This data is required for Phase 2 of the Bricmont proposal which completes the design and specifications of the total heat treating and cooling system for the process. This becomes the basis for developing the cost and space requirements for this component of the production line. The authors do not intend to award Phase 2 until the work done at Northwestern University discussed hereafter is completed. On or about May 1, 1999 a contract for a project entitled ``Effects of Steel Composition and Quench Rate on Microstructure and Mechanical Properties of Strapping'' to be performed at the Department of Materials Science and Engineering was awarded. The delay in initiating this project was due to the legal interpretation and final agreement of the intellectual provisions of the award by the author's attorneys, Northwestern's attorneys and the legal representative in the Chicago office of the DOE. The work to date includes rapid quenching of a number of different steel compositions and microstructure on an existing drop quench test apparatus. It was initially assumed that this procedure would simulate

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Heavy-Duty Rescue Straps For Coveralls

    NASA Technical Reports Server (NTRS)

    Waddell, Henry M.

    1988-01-01

    New type of strap on coveralls helps rescuers lift victims of industrial accidents. Made of heavy twill. New material, 1 in. wide and has breaking strength of 600 lb, sewn to coveralls with polyester thread in box "X" stitching. Reinforcing nylon webbing, 1 3/4 in. wide sewn with strap at attachment points.

  13. 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.

  14. 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.

  15. On the design and analysis of ultrabroadband antenna windows

    NASA Astrophysics Data System (ADS)

    Hara Prasad, R. V.; Lakshminarayana, D.

    1993-09-01

    Accounts are given of the design principles, analytical results, and experimental performance of two ultrawideband antenna windows operating in the 2-18 GHz range; the windows are of A-sandwich and C-sandwich construction. Curves are obtained for the theoretical and the practically obtainable power-transmission characteristics; while maximum A-sandwich transmission loss is below 1 dB, that of the C-sandwich is below 1.5 dB, over the complete band.

  16. 3D electromagnetic optimization of the front face of the ITER ICRF antenna

    NASA Astrophysics Data System (ADS)

    Louche, F.; Dumortier, P.; Messiaen, A.; Durodié, F.

    2011-10-01

    In the framework of the ion cyclotron resonance heating (ICRH) antenna development for ITER, a design based on an external matching concept has been proposed [1]. We present in this work a series of electromagnetic simulations of this design performed with the commercial code CST Microwave Studio [2]. On the one hand, we explore how various geometrical modifications of some parts of the antenna (the straps and the four-port junction) can practically double the RF power coupled to the plasma. This optimization is supported by transmission line analysis. On the other hand, we treat the important question of the opportunity to tilt the straps in the toroidal direction to follow the plasma curvature as close as possible. We show that a configuration with two toroidal segments is sufficient and that further segmentation is not necessary. This work also underlines significant progress in the realism of ICRH antenna modelling and the importance of considering realistic load shaping in the models.

  17. [Microstrip antenna design and system research of radio frequency identification temperature sensor].

    PubMed

    Yang, Hao; Yang, Xiaohe; Chen, Yuquan; Pan, Min

    2008-12-01

    Radio frequency identification sensor network, which is a product of integrating radio frequency identification (RFID) with wireless sensor network (WSN), is introduced in this paper. The principle of radio frequency identification sensor is analyzed, and the importance of the antenna is emphasized. Then three kinds of common antennae, namely coil antenna, dipole antenna and microstrip antenna, are discussed. Subsequently, according to requirement, we have designed a microstrip antenna in a wireless temperature-monitoring and controlling system. The measurement of factual effect showed the requirement was fulfilled. PMID:19166222

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. L-band slot antenna design for gigawatt-level single-pulse microwave sources

    SciTech Connect

    Haworth, M.D.; Calico, S.E.; Hendricks, K.J.; McGrath, D.T.; Spencer, T.A.; Clark, M.C.; Coleman, P.D.; Sedillo, R.C.

    1996-12-31

    One significant problem with the evacuated Vlasov antenna used in the present-day gigawatt-level, 1.2-Ghz magnetically insulated line oscillator (MILO) experiments is rf breakdown in the antenna aperture. In order to reduce the field stress inherent in a single-aperture antenna at gigawatt power levels, an 81-slot non-resonant (traveling wave) antenna has been constructed. The intent of this design is to reduce the rf electric field in any one aperture below the vacuum breakdown threshold, and yet maintain a desirable far-field pattern having a localized and intense power density profile. Here the authors report on cold testing results from the slot antenna as well as on theoretical analysis of the antenna using a transmission line model aided by computer simulations. In addition, experimental data obtained using this antenna on MILO are presented. Finally, improvements to the slot antenna design are given.

  3. Design of scanning spherical trireflector antennas with high aperture efficiency

    NASA Technical Reports Server (NTRS)

    Shen, Bing; Stutzman, Warren L.

    1993-01-01

    It is frequently desirable to scan the main beam of a large antenna system without moving the main aperture structure. Spherical reflectors have excellent potential in this application. However, they are not commonly used because of poor aperture efficiency and high side lobes in traditional implementations. This paper introduces a new dual-subreflector feed system design which does not require oversizing the spherical main reflector to accommodate scan and yet permits a controlled aperture illumination. The design yields high aperture efficiency, low cross-polarization, and low side lobes.

  4. 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.

  5. GPS Antenna Characterization Experiment (ACE): Receiver Design and Initial Results

    NASA Technical Reports Server (NTRS)

    Martzen, Phillip; Highsmith, Dolan E.; Valdez, Jennifer E.; Parker, Joel J. K.; Moreau, Michael C.

    2015-01-01

    The GPS Antenna Characterization Experiment (ACE) is a research collaboration between Aerospace and NASA Goddard to characterize the gain patterns of the GPS L1 transmit antennas. High altitude GPS observations are collected at a ground station through a transponder-based or "bent-pipe" architecture where the GPS L1 RF spectrum is received at a platform in geosynchronous orbit and relayed to the ground for processing. The focus of this paper is the unique receiver algorithm design and implementation. The high-sensitivity GPS C/A-code receiver uses high fidelity code and carrier estimates and externally supplied GPS message bit data in a batch algorithm with settings for a 0 dB-Hz threshold. The resulting carrier-to-noise measurements are used in a GPS L1 transmit antenna pattern reconstruction. This paper shows initial transmit gain patterns averaged over each block of GPS satellites, including comparisons to available pre-flight gain measurements from the GPS vehicle contractors. These results provide never-before-seen assessments of the full, in-flight transmit gain patterns.

  6. 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.

  7. 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.

  8. 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.

  9. The design of the fine antenna pointing system for Italsat

    NASA Astrophysics Data System (ADS)

    Galaurchi, A.; Losquadro, G.; Perrotta, G.

    Italsat's baseline design employs communications antennae-integrated RF sensors, in order to satisfy beam-pointing accuracy requirements of 0.03 deg at 3-sigma. These RF sensors are of the lobe-switching types. The system enters its autotracking mode only upon the receipt of a command sent from the ground station; it then goes through various submodes autonomously, performing verifications and making decisions. Tracking accuracy depends on the law of signal combination and the noise sensitivity of the measurements made.

  10. Orbit design for the Laser Interferometer Space Antenna (LISA)

    NASA Astrophysics Data System (ADS)

    Xia, Yan; Li, Guangyu; Heinzel, Gerhard; Rüdiger, Albrecht; Luo, Yongjie

    2010-01-01

    The Laser Interferometer Space Antenna (LISA) is a joint ESA-NASA mission for detecting low-frequency gravitational waves in the frequency range from 0.1 mHz to 1 Hz, by using accurate laser interferometry between three spacecrafts, which will be launched around 2018 and one year later reach their operational orbits around the Sun. In order to operate successfully, it is crucial for the constellation of the three spacecrafts to have extremely high stability. Based on the study of operational orbits for a 2015 launch, we design the operational orbits of beginning epoch on 2019-03-01, and introduce the method of orbit design and optimization. We design the orbits of the transfer from Earth to the operational orbits, including launch phase and separation phase; furthermore, the relationship between energy requirement and flight time of these two orbit phases is investigated. Finally, an example of the whole orbit design is presented.

  11. Thermo-structural development of the ITER ICRF strap housing module

    NASA Astrophysics Data System (ADS)

    Winkler, K.; Shannon, M.; Lockley, D.

    2014-02-01

    Since March 2010 the preliminary design of the ITER ICRF Antennas have been developed by CYCLE, a consortium consisting of IPP (Garching), CCFE (Culham), CEA (Cadarache), Politecnico di Torino (Torino) and LPPERM/KMS (Brussels). This paper describes the steps taken to develop the present geometry of the triplet pair Strap Housing Module from a thermal and structural perspective, and shows the critical areas of the structure. Key issues are the manufacturability, (achieved by HIPing - Hot Isostatic Pressing), the ability to handle the radiating plasma thermal flux of 0.35 MW/m2, the RF losses and the neutronic radiation. HIPing is necessary to achieve the complicated system of cooling channels inside the structure, which divides the coolant equally in order to supply each strap in the triplet with 1 l/s of water. The components have also to withstand the strong mechanical forces generated by plasma disruptions affecting all internal structures and the elevated design cooling water pressure of 5MPa. In order to maximise reliability, joints between different materials in the cooling water system have been kept to a minimum. Therefore, in the interests of fabricability and availability, the whole structure is manufactured out of stainless steel (316L(N)IG). The low conductivity of 316L(N)IG demands small wall thicknesses to avoid hot spots; however this reduces the mechanical strength. Consequently an in depth FEM analysis is presented, which was used to find and to improve the critical aspects of this important component and was the best means of finding the optimum between thermal and mechanical performance.

  12. Thermo-structural development of the ITER ICRF strap housing module

    SciTech Connect

    Winkler, K.; Shannon, M.; Lockley, D.

    2014-02-12

    Since March 2010 the preliminary design of the ITER ICRF Antennas have been developed by CYCLE, a consortium consisting of IPP (Garching), CCFE (Culham), CEA (Cadarache), Politecnico di Torino (Torino) and LPPERM/KMS (Brussels). This paper describes the steps taken to develop the present geometry of the triplet pair Strap Housing Module from a thermal and structural perspective, and shows the critical areas of the structure. Key issues are the manufacturability, (achieved by HIPing - Hot Isostatic Pressing), the ability to handle the radiating plasma thermal flux of 0.35 MW/m{sup 2}, the RF losses and the neutronic radiation. HIPing is necessary to achieve the complicated system of cooling channels inside the structure, which divides the coolant equally in order to supply each strap in the triplet with 1 l/s of water. The components have also to withstand the strong mechanical forces generated by plasma disruptions affecting all internal structures and the elevated design cooling water pressure of 5MPa. In order to maximise reliability, joints between different materials in the cooling water system have been kept to a minimum. Therefore, in the interests of fabricability and availability, the whole structure is manufactured out of stainless steel (316L(N)IG). The low conductivity of 316L(N)IG demands small wall thicknesses to avoid hot spots; however this reduces the mechanical strength. Consequently an in depth FEM analysis is presented, which was used to find and to improve the critical aspects of this important component and was the best means of finding the optimum between thermal and mechanical performance.

  13. 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.

  14. Microstrip-antenna design for hyperthermia treatment of superficial tumors.

    PubMed

    Montecchia, F

    1992-06-01

    Microstrip antennas have many different advantages over other RF/MW radiative applicators employed for superficial hyperthermia treatment. This is mainly due to their compact and body-conformable structure as well as to printed circuit board techniques, both of which allow a wide design flexibility for superficial tumor heating. Among the wide variety of radiator configurations, three microstrip antennas of increasing complexity with electromagnetic and heating characteristics potentially suitable as applicators for superficial hyperthermia have been designed, developed, and tested in different radiative conditions: a microstrip disk, a microstrip annular-slot, and a microstrip spiral. Electromagnetic design criteria are presented together with the determinations of the applicator return loss versus frequency and thermograms of the near-field heating pattern in muscle-like phantom. The results are in good agreement with theory and indicate that: i) the operating frequency is either single or multiple according to the applicator-mode, "resonant" or "traveling-wave," and can be chosen in the useful frequency range for hyperthermia (200-1000 MHz) according to the tumor cross-section and depth; ii) the heating pattern flexibility increases going from the simple geometry disk to the annular-slot and spiral applicators; iii) a distilled-water bolus is required; iv) the annular-slot applicator exhibits the highest efficiency, while the spiral applicator provides the best performance. PMID:1601439

  15. Microstrip-antenna design for hyperthermia treatment of superficial tumors

    SciTech Connect

    Montecchia, F. )

    1992-01-01

    Microstrip antennas have many different advantages over other RF/MW radiative applicators employed for superficial hyperthermia treatment. This is mainly due to their compact and body-conformable structure as well as to printed circuit board techniques, both of which allow a wide design flexibility for superficial tumor heating. Among the wide variety of radiator configurations, three microstrip antennas of increasing complexity with electromagnetic and heating characteristics potentially suitable as applicators for superficial hyperthermia have been designed, developed, and tested in different radiative condition: a microstrip disk, a microstrip annular-slot, and a microstrip spiral. Electromagnetic design criteria are presented together with the determinations of the applicator return loss versus frequency and thermograms of the near-field heating pattern in muscle-like phantom. The results are in good agreement with theory and indicated that: the operating frequency is either single or multiple according to the applicator-mode, 'resonant' or 'traveling-wave', and can be chosen in the useful frequency range for hyperthermia according to the tumor cross-section and depth; the heating pattern flexibility increases going form the simple geometry disk to the annular-slot and spiral applicators; a distilled-water bolus is required; the annular-slot applicator exhibits the highest efficiency, while the spiral applicator provides the best performance.

  16. 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.

  17. Application Of High Conductivity Carbon Fibre Materials For Flexible Thermal Straps

    NASA Astrophysics Data System (ADS)

    Usinger, R.; Delouard, P.; Miller, G.

    2012-07-01

    In a recently completed ESA GSTP project RUAG Space successfully demonstrated that thermal straps made from high conductivity carbon fibres can provide larger heat transport capability than conventional metallic designs at reduced mass. To prove the feasibility of the concept, breadboard models of flexible carbon fibre straps were manufactured and tested in laboratory environment. The end- to-end conductance measured in a thermal vacuum test correlated well with the prediction made with a simple thermal mathematical model. Mechanical tests were performed on the straps to check whether and to which extent the thermal performance is degraded by mechanical loads. The results from these tests indicate that the selected strap design is surprisingly tolerant against mechanical damage.

  18. 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.

  19. 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.

  20. Study and design of a broadband coplanar waveguide-fed modified folded slot antenna

    NASA Astrophysics Data System (ADS)

    Ali, M.; Usaha, R.; Hu, Y.

    2004-08-01

    This paper presents the study and design of a coplanar waveguide-fed broadband modified folded slot antenna, including new techniques to achieve broad impedance bandwidth when the antenna size is small. Antenna impedance and bandwidth are investigated as functions of slot parameters, substrate dielectric constant, and substrate thickness. Prototypes of broadband antennas are fabricated on RO4003 (ɛr = 3.38) and are measured. Two types of antennas are proposed with respective bandwidths of 44.4 and 80% with less than 2:1 VSWR.

  1. Design and Optimization of LTE 1800 MIMO Antenna

    PubMed Central

    Wong, Huey Shin; Islam, Mohammad Tariqul

    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. PMID:24967440

  2. 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. PMID:24967440

  3. Design and analysis of coupled-resonator reconfigurable antenna

    NASA Astrophysics Data System (ADS)

    Hossain, M. I.; Faruque, M. R. I.; Islam, M. T.; Ali, M. T.

    2016-01-01

    In this paper, a coupled resonator with the microstrip patch antenna is proposed as a frequency reconfigurable antenna. The ground plane of the proposed microstrip patch antenna is modified with the proposed resonator structure to obtain reconfigurable characteristics. The resonator structure consists of two square split rings. The incorporation of proposed resonator structure with antenna makes it single-band antenna. The characteristics of proposed resonator structure can effectively deactivate by closing the splits of rings using switches, and hence, the dual-band characteristics of the antenna are recovered. The finite integration technique of computer simulation technology microwave studio is used throughout the investigation. The measurement of antenna performances is taken in an anechoic chamber. The measured and simulated performances of proposed reconfigurable antenna show very good agreement.

  4. 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.

  5. New ultrawide-bandwidth horn-fed dipole GPR antenna design

    NASA Astrophysics Data System (ADS)

    Chen, Chi-Chih; Higgins, Matthew B.

    2000-04-01

    A novel broad bandwidth dual-polarization GPR antenna was also developed for collecting fully polarimetric data over a wide frequency range (20 MHz to approximately 800 MHz). This new design was improved from its single-polarization version introduced by Chen (1997). The new design features improved stability and directivity over conventional surface-based GPR antennas. Such antenna is currently applied to discriminate buried UXO's from other false alarm reduction.

  6. 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;

  7. Design features of the Orion satellite antenna subsystem

    NASA Astrophysics Data System (ADS)

    Waterfield, T. R.

    The ORION satellites (first launch 1994) will provide flexible, high capacity Ku-band communications between and within North America and Europe. Four-fold frequency re-use allows the provision of thirty-four transponders per spacecraft, with two-way networking traffic to 1.2 meter rooftop Very Small Aperture Terminals (VSAT). This paper provides an overview of the communications antenna subsystem and highlights some of the novel and sophisticated design features. These include the following: numerically shaped, gridded reflectors; computer optimized multi-horn feed geometry; feed coefficients optimized under mutual coupling; reconfigurable beams via on-board switching; very low thermal-distortion reflectors; novel sunshield design; and two-axis boresight trimming. Selected analyses and measurement results available at the time of writing are presented.

  8. 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.

  9. Design of miniaturized printed monopole antennas through phase-compensation

    NASA Astrophysics Data System (ADS)

    Scorrano, Luca; Bilotti, Filiberto; Vegni, Lucio

    2009-05-01

    In this paper, the guidelines for the design of compact transmission-line (TL) metamaterial inspired monopole antennas are presented. The main difference between the proposed setup and the ones already present in the literature, based on phase-compensation phenomena enabled by TL-metamaterials, is that the present structure can be realized in fully planar technology. This peculiar feature allows minimizing the non-idealities introduced by vias and parallel plate capacitors used in conventional setups, which need to be soldered on the board. On the other hand, the proposed radiating devices are characterized by relatively low production costs, due to their planar configuration. The operation principles of the proposed radiators are detailed in the paper, giving the reader the necessary information to perform the design. Some examples are finally presented and tested through proper full-wave simulations performed with CST Studio Suite 2009.

  10. 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

  11. 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.

  12. Design and Performance of the H_infinity Controller for the Beam-Waveguide Antenna

    NASA Astrophysics Data System (ADS)

    Gawronski, W.

    2011-02-01

    The linear-quadratic-Gaussian (LQG) controllers are currently implemented at the beam-waveguide (BWG) antennas. Each BWG antenna has a different set of LQG coefficients, obtained by tuning and testing each controller individually. Individual coefficients for each antenna are necessary, since the antenna dynamics are not identical and the derivation of the LQG coefficients is a labor-intensive process. Hence, the process could be simplified by using single set of coefficients for all BWG antennas. The purpose of the work reported here is to develop a single set of servo coefficients for all BWG antennas. This is achieved by using the H_infinity controller approach and a robust design technique. In this article, the analysis of the H_infinity controller was performed, and the results obtained (by executing over 10,000 Monte Carlo simulations) showed that it is feasible to use a single set of the H_infinity controller coefficients at all BWG antennas, and that the H_infinity controller performance is similar to or exceeds the "standard" LQG controller performance, i.e., except for the DSS-25 antenna controller performance. Note that the latter controller was derived exceptionally strong. At the remaining antennas, the controller coefficients are weaker, and they represent the "standard" LQG performance. This approach simplifies the development of the controller coefficients for BWG antennas, and simplifies the servo performance evaluation, since the performance should be similar for all six BWG antennas.

  13. 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

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    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.

  16. 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.

  17. Transformation of design formulae for feed line of triangular microstrip antenna

    NASA Astrophysics Data System (ADS)

    Mathur, Monika; Singh, Ghanshyam; Bhatnagar, S. K.; Swami, Swati; Vats, Abhijat

    2016-03-01

    In wireless communication system microstrip antenna is the key component. Popular shapes of patch for microstrip are rectangular, triangular and circular. A new transformation design formulae for feed line of rectangular microstrip antenna by using equivalent design concept were presented by the authors. That says one designed antenna for a given frequency on any substrate can be transformed into another substrate material for the same design frequency by simply multiply a factor ψ to the all dimensions of patch, length of feed line and some power of ψ for feed line width (where ψ is the square root of the ratio of dielectric constants of those two designs). This paper presents that the same formulae of that rectangular transformation feed line can also be applicable for triangular shape microstrip antenna transformation. The process was repeated for the triangular shape patch microstrip antenna as applied for rectangular shape and the simulation results were surprisingly the same for it by applying the same transformation formulae.

  18. Dual reflector antenna design software - Application to offset-fed shaped elliptical aperture systems

    NASA Astrophysics Data System (ADS)

    Kossiavas, Isabelle

    1992-04-01

    To facilitate the design of dual reflector antennas, the interactive, graphic CA2R software package handles centrally or offset-fed structures with quadric or shaped reflectors. Surface shaping, based on geometrical optics, improves the antenna's efficiency and the sidelobe level. Existing techniques are applied to an offset-fed antenna with an elliptical projected aperture. An original numerical method to minimize crosspolar components is also presented.

  19. 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.

  20. Performance assessment of the ITER ICRF antenna

    NASA Astrophysics Data System (ADS)

    Durodié, F.; Vrancken, M.; Bamber, R.; Colas, L.; Dumortier, P.; Hancock, D.; Huygen, S.; Lockley, D.; Louche, F.; Maggiora, R.; Milanesio, D.; Messiaen, A.; Nightingale, M. P. S.; Shannon, M.; Tigwell, P.; van Schoor, M.; Wilson, D.; Winkler, K.; Cycle Team

    2014-02-01

    ITER's Ion Cyclotron Range of Frequencies (ICRF) system [1] comprises two antenna launchers designed by CYCLE (a consortium of European associations listed in the author affiliations above) on behalf F4E for the 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Design of a Compact Hexagonal Monopole Antenna for Ultra—Wideband Applications

    NASA Astrophysics Data System (ADS)

    Shaalan, Abdo Abdelmonem; Ramadan, M. I.

    2010-08-01

    This paper presents two design compact hexagonal monopole antennas for ultra-wideband applications. The two antennas are fed by a single microstrip line . The Zeland IE3D version 12 is employed for analysis at the frequency band of 4 to 14 GHz which has approved as a commercial UWB band. The experimental and simulation results exhibit good agreement together for antenna 1. The proposed antenna1 is able to achieve an impedance bandwidth about 111%. The proposed antenna2 is able to achieve an impedance bandwidth about (31.58%) for lower frequency and (62.54%) for upper frequency bandwidth. A simulated frequency notched band ranging from 6.05 GHz to 7.33 GHz and a measured frequency notched band ranging from 6.22 GHz to 8.99 GHz are achieved and gives one narrow band of axial ratio (1.43%). The proposed antennas can be used in wireless ultra-wideband (UWB) communications.

  6. Design of a broadband hexagonal-shaped zeroth-order resonance antenna with metamaterials

    NASA Astrophysics Data System (ADS)

    Woo, Dong Sik; Kim, Kang Wook; Choi, Hyun-Chul

    2014-11-01

    A broadband hexagonal-shaped metamaterials (MTMs)-based zeroth-order resonant (ZOR) antenna was designed and fabricated. The hexagonal shape of a top patch on a mushroom structure makes not only direct-current paths between the two ends of the patch but also round-current paths along the outside of the patch, thereby widening the resonance frequency of the mushroom MTM antenna. According to the shape of the hexagon patch, the presented antenna achieved impedance bandwidth of 58.6% corresponding to ultra-wideband technology. The proposed ZOR antenna was modeled by utilizing a composite right- and left-handed (CRLH) transmission line and provided 4 to 9.3 dBi of the antenna gain with reduced size as compared to conventional microstrip antennas at Ku- to K-band frequencies.

  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. 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.

  9. High-gain backup antenna design for Pioneer Venus Orbiter spacecraft

    NASA Technical Reports Server (NTRS)

    Glaser, J. I.

    1986-01-01

    The development and performance is described of a high-gain antenna designed to serve on the Pioneer Venus Orbiter spacecraft as a backup to the principal high-gain antenna unit in the unlikely event the mechanically despun antenna mechanism malfunctioned. The final design, a center-fed standing wave array of six sleeve dipoles enclosed in a fiber glass radome, performed successfully, as did all the antennas, on the Pioneer Orbiter spacecraft which was launched on May 20, 1978, as part of the Pioneer Venus mission. Photographs of experimental models giving details of design and construction are included, as well as graphs showing measured pattern and impedance matching characteristics of the subject antenna.

  10. 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.

  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. Computer-based designing of waveguide radiators of arbitrary cross section for antenna arrays

    NASA Astrophysics Data System (ADS)

    Voskresenskii, D. I.; Grinev, A. Iu.; Ilinskii, A. S.; Kotov, Iu. V.

    1980-02-01

    A multistep method is proposed for designing waveguide radiators for use in antenna arrays. A rigorous electrodynamic method for structure analysis is developed, along with a computer program and a numerical algorithm. The aperture performance of a quadruple-ridge rectangular waveguide in a phased array is examined, along with the directivity patterns of H-shaped, square, and circular radiators in antenna arrays.

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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.

  1. Design of dual band wearable antenna using metamaterials.

    PubMed

    Afridi, Adeel; Ullah, Sadiq; Khan, Shahbaz; Ahmed, Aziz; Khalil, Akhtar Hussain; Tarar, Munir Ahmad

    2013-01-01

    This paper presents two types of dual band (2.4 and 5.8 GHz) wearable planar dipole antennas, one printed on a conventional substrate and the other on a two-dimensional metamaterial surface (Electromagnetic Bandgap (EBG) structure). The operation of both antennas is investigated and compared under different bending conditions (in E and H-planes) around human arm and leg of different radii. A dual band, Electromagnetic Band Gap (EBG) structure on a wearable substrate is used as a high impedance surface to control the Specific Absorption Rate (SAR) as well as to improve the antenna gain up to 4.45 dBi. The EBG inspired antenna has reduced the SAR effects on human body to a safe level (< 2W/Kg). I.e. the SAR is reduced by 83.3% for lower band and 92.8% for higher band as compared to the conventional antenna. The proposed antenna can be used for wearable applications with least health hazard to human body in Industrial, Scientific and Medical (ISM) band (2.4 GHz, 5.2 GHz) applications. The antennas on human body are simulated and analyzed in CST Microwave Studio (CST MWS). PMID:24779146

  2. 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.

  3. Development and design of dual-band, multi-function remote sensing antennas

    NASA Astrophysics Data System (ADS)

    Creticos, Justin P.

    This dissertation details the theoretical development, design, fabrication, and testing of two remote sensing antennas. The antennas operate in Ku and Ka bands and must support multiple beams, polarizations, and frequencies with a single aperture. The first antenna, developed for NASA's High-Altitude Imaging Wind and Rain Airborne Profiler, is a single, offset-fed reflector that supports dual-band beams incident at 30° and 40° off-nadir. The antenna uses two compact, dual-band feeds moved away from the reflector's focal point to meet the dual beam requirement. The radar is to be flown on the Global Hawk Uninhabited Aerial Vehicle which has a small payload bay requiring the feeds to be both rugged and compact. The second antenna, developed for Remote Sensing Solutions' Dual-Wavelength Precipitation Radar, is a dual-offset Gregorian reflector. The antenna supports a single, dual-band, beam with dual-polarization at each band. Additionally, the antenna has high polarization purity and matched half power beamwidths at Ku and Ka bands. The strict requirements of the antenna are met by precisely controlling feed radiation characteristics. The two antennas necessitated several advances in feed design. A foam sleeve is demonstrated as an effective method to reduce the beamwidth of a tapered dielectric rod antenna. The foam sleeve is an attractive design because it allows dual-band feeds where a corrugated horn is used to control radiation at lower frequencies and the sleeve corrected rod is used to control the upper band. By judiciously choosing sleeve material, independent control of the radiation pattern and phase center at each band is achieved allowing higher performance feeds. This dissertation also focuses on new developments in the backend design of feeds. Specifically, the use of tuning arms in the feed backend and double ridged waveguide to couple the signal into the feed allow more compact designs with greater bandwidth.

  4. Design of a Five-Band Internal Antenna for Handsets

    NASA Astrophysics Data System (ADS)

    Zhu, Anfu; Li, Jianxing; Zhang, Anxue; Jiang, Yansheng

    2012-06-01

    A novel compact five-band internal handset antenna covering LTE (746-806 MHz), GSM850 (824-894 MHz), GSM900 (890-960 MHz), DCS (1710-1880 MHz) and PCS (1850-1990 MHz) bands is presented. To enhance the bandwidths of the proposed antenna both at the low frequency band and high frequency band, a rectangular slot with a proper size is removed in the ground plane at an appropriate location. Both the simulated results and measured results show that reasonable radiation patterns and antenna gains for each frequency band are achieved.

  5. 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.

  6. 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). PMID:27533470

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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. PMID:25664993

  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. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Design of 45-degree Linearly Polarized Substrate Integrated Waveguide-fed Slot Array Antennas

    NASA Astrophysics Data System (ADS)

    Zhang, Qingfeng; Lu, Yilong

    2008-11-01

    This paper presents a method of designing substrate integrated waveguide-fed (SIW-fed) slot array antennas. The design theory is based on the circuit model of slot and via as well as the reflection canceling. To prove the feasibility of this method, a 10-element K-band SIW-fed 45-degree linearly polarized slot array antenna with uniform power distribution is designed. By full-wave simulation, the antenna has a good impedance bandwidth of 7.5% and uniform power distribution. Besides, a maximum gain of 15.3dBi is obtained in the broadside and the cross polarization is suppressed below -23.5dB in the boresight. This type of SIW-fed slot array antennas can be a good candidate for microwave and millimeter-wave applications, especially for auto-motive collision-avoidance radar systems.

  2. 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.

  3. 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

  4. 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.

  5. Design and performance of a 4.5GHz circularly polarized YBa 2Cu 3O 7 microstrip antenna

    NASA Astrophysics Data System (ADS)

    Zhu, M. H.; Cao, B. S.; Zhang, X. X.; Li, W. H.; Yuan, H. J.; Wang, Y. J.; Zhang, L. W.; Dong, D. J.; Liu, M. L.; Cui, D. F.; He, M.; Zhou, Y. L.; Liu, T. J.

    1997-08-01

    A 4.5GHz circularly polarized YBCO microstrip antenna was designed and fabricated. Measurements showed that at 77K the superconducting antenna had about 3dB gain improvement over the comparable silver antenna, in agreement with the calculated results using the modified Green function method.

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

    PubMed

    Jiang, Ping; Yang, Huajun; Mao, Shengqian

    2015-10-01

    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. PMID:26480125

  7. 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.

  8. On the Practical Design of Small Terminal Antennas for Mobile Applications

    NASA Astrophysics Data System (ADS)

    Skrivervik, Anja K.; Martínez-Vázquez, Marta; Mosig, Juan R.

    Mobile communication have become an important part of telecommunications. Original applications like paging, mobile phones or GPS have shown a tremendous growth, and new applications are emerging every day: tagging, wireless computer links, wireless microphones, remote control, wireless multimedia links, satellite mobile phones, wireless internet. Mobile means light, small, with low energy consumption and appealing designs. Technology has evolved very fast to satisfy these needs in rapidly growing markeds: chips are becoming smaller, consume less current, are more efficient and perform more complex operations. The antennas however have not experienced the same evolution, as the size of an antenna is mainly dictated by the frequency band it has to transmit or receive. Thus, the art of antenna miniaturization is an art of compromise: one has to design the smallest possible antenna, which is still suitable for a given application regarding its radiation characteristics. Or in other words, one looks for the best compromise between volume, bandwidth and efficiency. In this paper, we will go through classical design techniques, starting from ultra small antennas and going UWB antennas over multiband designs.

  9. 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.

  10. 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.

  11. 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.

  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. PMID:24723835

  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 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.

  15. Status of the JET ITER-Like Antenna High-Power Prototype Test Program

    SciTech Connect

    Goulding, R.H.; Baity, F.W.; Fadnek, A.; Freudenberg, K.D.; Nelson, B.E.; Rasmussen, D.A.; Sparks, D.O.; Durodie, F.; Nightingale, M.; Walton, R.

    2005-09-26

    Previous tests of a High Power Prototype (HPP) comprising one quadrant of the JET ITER-Like ICRF Antenna have indicated the need for some design modifications in order to achieve 10 s pulses coupling the full design power (7.1 MW) into the reference plasma load (R' = 4 {omega}/m). These modifications have now been made to the HPP, as well as to the design of the ITER-Like Antenna itself. In particular, maximum current densities have been reduced or otherwise accommodated in key areas. New current straps for the HPP have been fabricated from stereo-lithography-based investment castings. Design modifications to the antenna enclosure have also been implemented. This work has been materially assisted through the use of CST Microwave Studio (MWS), a commercially available 3-D electromagnetic modeling package. Essentially the full engineering CAD model of the HPP current straps and antenna enclosure has been ex-ported from ProE to MWS. Computed current density profiles have been introduced into an ANSYS thermal model. These activities will be discussed, as well as the current status of the HPP test program.

  16. 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

  17. 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.

  18. On the JET ITER-Like ICRF antenna and implications for the ICRF system for ITER

    NASA Astrophysics Data System (ADS)

    Durodie, Frederic; Nightingale, Mark

    2009-11-01

    A new ``ITER-Like'' Ion Cyclotron Resonance Frequency (ICRF) antenna was installed on the JET tokamak in 2007 and extensively operated on plasma since May 2008 for a wide range of conditions (frequencies: 33, 42 and 47 MHz, L- and ELMy H-mode plasmas, antenna strap - plasma separatrix distances from 9 to 17 cm). Aspects relating to the potential performance and design of the ITER system, will be discussed: (i) the wave coupling performance and validation of the TOPICA modelling code used to predict the coupled power in ITER; (ii) the operation at high coupled power density (up to 6.2 MW/m^2 in L-mode, 4.1 MW/m^2 in H-mode) and high RF voltage on the antenna structure (up to 42 kV); (iii) the coupling of ICRF power during fast variations (ms) in coupling occurring during ELMs and (iv) antenna control in the presence of high mutual coupling between antenna straps.

  19. 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.

  20. roof truss detail, historic strap hinge detail Chopawamsic Recreational ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    roof truss detail, historic strap hinge detail - Chopawamsic Recreational Demonstration Area - Cabin Camp 1, Main Arts and Crafts Lodge, Prince William Forest Park, Triangle, Prince William County, VA

  1. Design and Characterization of Planar Traveling Wave Dipole Antennas Using Resistive and Reactive Loading

    NASA Astrophysics Data System (ADS)

    Grzybowski, Richard Robert

    1992-01-01

    It is well known that the current distribution on dipole antennas exists primarily as standing waves. For this reason, the input impedance of a dipole antenna is a strong function of frequency. In contrast, a traveling wave antenna possesses an input impedance that is comparatively frequency independent. An important result of this reduced frequency dependence is the decrease in VSWR and an increase in bandwidth for a given antenna. In the past, free standing, traveling wave dipoles have been realized by the incorporation of distributed resistive loading along the length of the antenna. This type of loading permits the rapid attenuation of a traveling wave current as it proceeds toward the feed point. These experiments were performed at frequencies of several hundred megahertz. Resistive loading, however, reduces the radiation efficiency of the antennas by dissipating some of the input power as heat. This dissipative power loss may be overcome by utilizing reactive loading. This work discusses the design and characterization of planar traveling wave dipole antennas in the frequency range of X-through Ku-band. All of the dipole antennas treated were characterized with the aid of a small loop magnetic field probe constructed for that purpose. The magnetic field probe was used to quantitatively measure the surface current magnitude and phase distributions along the lengths of the dipoles. The planar antennas considered include printed microstrip dipoles that incorporate either resistive or reactive loading schemes along their lengths. These printed metal dipoles range in length from one quarter of a wavelength to over five wavelengths at 20 GHz. In addition, silicon traveling wave dipoles obtained via conductivity modulation are also evaluated.

  2. 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.

  3. 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.

  4. 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.

  5. Design of CPW fed printed slot antenna with circular polarization for UWB application

    NASA Astrophysics Data System (ADS)

    Choudhary, N.; Tiwari, A.; Jangid, K. G.; Sharma, B. R.; Saini, J. S.; Kulhar, V. S.; Bhatnagar, D.

    2016-03-01

    This paper reports the design and performance of a CPW-fed circularized polarized elliptical slot antenna for UWB (ultra wide band) applications. The circular polarization is achieved by applying triangular stubs in the ground plane. The overall volume of this antenna is 40mm × 40 mm × 1.59 mm. The proposed antenna is simulated by applying CST Microwave Studio simulator. This elliptical patch slot antenna provides broad impedance bandwidth (3.1GHz to 10.6 GHz) with maximum gain 4.31dB at 4.45GHz. The simulated 3-dB axial ratio bandwidth is close to 2.51GHz (from 4.76GHz to 7.27GHz) which is 41.76% with respect to the central frequency 6.01GHz.

  6. Design and analysis of inverted H shape dual band patch antenna for microwave application

    NASA Astrophysics Data System (ADS)

    Ullah, M. Habib; Islam, M. T.; Mandeep, J. S.; Misran, N.; Reaz, M. B. I.

    2013-04-01

    Design and analysis of an inverted H shape printed dual band patch antenna has been presented in this paper. The proposed antenna has designed by 3-D full wave high frequency electromagnetic simulator HFSS and printed in low cost, durable epoxy polymer resin composite material substrate. The printed antenna prototype has been measured in a standard far field anechoic electromagnetic field measurement chamber. The measured results have analyzed by using computer aided plotting tool OriginPro 8.5. Measured -10 dB return loss bandwidth 3.25 GHz from 9.75 GHz to 13 GHz with peak gain 8.5 dBi have been achieved. The proposed antenna has obtained 0.63 dBi gain with 96% efficiency at lower band 10.3 GHz and 6.03 dBi gain with 84.2% efficiency at upper band 12.5 GHz. The almost steady radiation pattern makes the proposed antenna appropriate for part of X and Ku band applications. Moreover, the input impedance and current distribution along the radiating patch of the proposed antenna have also been analyzed in this paper.

  7. Analysis and design of a wideband dual-polarized antenna based on the principle of Huygens' source

    NASA Astrophysics Data System (ADS)

    Seo, Hyukjun

    Analysis and designs of wideband dual-polarized antennas for mobile wireless communication systems are presented. The concept for Huygens' sources, which are combinations of electric and magnetic dipoles, is used. As a result a wideband unidirectional antenna, which consists of a planar dipole and a slot, is selected for the antenna element. This study aims at designing a dually polarized antenna with wideband performance. The first part of the study discusses the performance of the linearly polarized antenna element at 2.5 GHz. Several design parameters associated with the antenna element are addressed. To improve the performance and increase the bandwidth, a twin-fed hook-shaped probe feeding technique is applied. Prototype antennas are fabricated and tested, and good agreement between the simulated and measured results is obtained. The second part of this study is extended to design the wideband dual-polarized patch antenna. Problems associated with the practical implementation of the dual-polarized antenna in printed form are discussed. The wideband performance of the present antenna is examined by shielding the dielectric substrate from the radiating region. The proposed antenna is fabricated and tested. In addition, a metallic side wall is adopted for suppressing the back radiation. The study for designing a possible candidate for a novel dual-polarized antenna by embedding an electromagnetic bandgap (EBG) structure is investigated. Analysis for unit-cells of mushroom-like and wideband uniplanar EBG structures is performed, and simple monopoles are used for exciting the EBG embedded antenna. The presented antennas find many possible applications in many recent wireless communication systems like 3G, 3GPP Long Term Evolution (LTE), 4G, Wi-MAX, and Wi-Bro.

  8. Design and analysis of a conformal patch antenna for a wearable breast hyperthermia treatment system

    NASA Astrophysics Data System (ADS)

    Curto, Sergio; Ramasamy, Manoshika; Suh, Minyoung; Prakash, Punit

    2015-03-01

    To overcome the limitations of currently available clinical hyperthermia systems which are based on rigid waveguide antennas, a wearable microwave hyperthermia system is presented. A light wearable system can improve patient comfort and be located in close proximity to the breast, thereby enhancing energy deposition and reducing power requirements. The objective of this work was to design and assess the feasibility of a conformal patch antenna element of an array system to be integrated into a wearable hyperthermia bra. The feasibility of implementing antennas with silver printed ink technology on flexible substrates was evaluated. A coupled electromagnetic-bioheat transfer solver and a hemispheric heterogeneous numerical breast phantom were used to design and optimize a 915 MHz patch antenna. The optimization goals were device miniaturization, operating bandwidth, enhanced energy deposition pattern in targets, and reduced Efield back radiation. The antenna performance was evaluated for devices incorporating a hemispheric conformal groundplane and a rectangular groundplane configuration. Simulated results indicated a stable -10 dB return loss bandwidth of 88 MHz for both the conformal and rectangular groundplane configurations. Considering applied power levels restricted to 15 W, treatment volumes (T>410C) and depth from the skin surface were 11.32 cm3 and 27.94 mm, respectively, for the conformal groundplane configuration, and 2.79 cm3 and 19.72 mm, respectively, for the rectangular groundplane configuration. E-field back-radiation reduced by 85.06% for the conformal groundplane compared to the rectangular groundplane configuration. A prototype antenna with rectangular groundplane was fabricatd and experimentally evaluated. The groundplane was created by printing silver ink (Metalon JS-B25P) on polyethylene terephthalate (PET) film surface. Experiments revealed stable antenna performance for power levels up to 15.3 W. In conclusion, the proposed patch antenna with

  9. 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.

  10. 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.

  11. 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. PMID:26186795

  12. 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 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap....

  13. 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 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap....

  14. 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 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap....

  15. 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 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5560 Gas mask head strap....

  16. "A 'one-piece' gutter orthosis/strapping alternative".

    PubMed

    Schoell, Christopher J

    2013-01-01

    Patients often have difficulty securing and positioning finger orthoses (splints). Using standard strapping materials molded directly into the orthotic device, this author describes an alternative strapping system for these small finger orthoses. -Victoria Priganc, PhD, OTR, CHT, CLT, Practice Forum Editor. PMID:22959536

  17. 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.

  18. The design of a microstrip antenna array for a UHF space telemetry link

    NASA Technical Reports Server (NTRS)

    Post, R. E.; Stephenson, D. T.

    1981-01-01

    An array of microstrip antenna panels was designed for use on a small instrumented satellite as part of a 400-MHz telemetry link between that satellite and NASA's shuttle spacecraft. A roughly omnidirectional phi-plane pattern was desired. The 1.4-wavelength diameter of the satellite and the various ports and structures on its surface presented strong constraints on the antenna array design. Eight antennas, each one a quarter-wavelength panel with one radiating and one shorted edge, were chosen. A phi-plane pattern ripple of 4.4 dB and a gain of at least 0.1 dB relative to a half-wavelength dipole were realized. The design technique used for the individual antenna panels included the study of feed-point location for impedance matching and the effect of losses in the dielectric. A superposition method was used to synthesize the radiation patterns for different numbers and different excitations of antennas on the satellite.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1993-11-01

    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.

  1. Beam-Waveguide Antenna Servo Design Issues for Tracking Low-Earth-Orbiting Satellites

    NASA Astrophysics Data System (ADS)

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

    1993-07-01

    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 treducing 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 oversampled monopulse signal is described.

  2. 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.

  3. 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.

  4. 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.

  5. Design and Performance of the WISDOM Antenna System aboard the ExoMars Rover

    NASA Astrophysics Data System (ADS)

    Plettemeier, D.; Ciarletti, V.; Hamran, S.; Corbel, C.; Linke, S.; Benedix, W.

    2009-04-01

    A full polarimetric antenna system on board the ExoMars rover is part of the Experiment "Water Ice and Subsurface Deposit Observations on Mars" (WISDOM). The WISDOM-Experiment is a Ground Penetrating Radar (GPR) selected to be part of the Pasteur payload aboard the rover of the ExoMars mission. The Pasteur Panoramic Instruments (wide angle camera PANCAM, infrared spectrometer MIMA and WISDOM) will perform large-scale scientific investigations at the sites the Rover will visit. Among these instruments, WISDOM is the only one that can provide a view of the subsurface structure prior to drilling. WISDOM is the first space borne GPR aboard a rover and has been designed to characterize the shallow subsurface structure of Mars. WISDOM will give for the first time access to the geological structure, electromagnetic nature, and, possibly, of hydrological state of the shallow subsurface by retrieving the layering and properties of the buried reflectors. It will address some important related science questions regarding the planet present state and past evolution. The measured data will also be used to determine the most promising locations at which to obtain underground samples with the drilling system mounted on board the rover. The instrument objective for WISDOM is to get high-resolution measurements down to 2-meters depth in the Martian crust. The radar is a gated step frequency system covering the frequency range from 500 MHz to 3 GHz. The radar is fully polarimetric and makes use of four ultra wideband Vivaldi antennas. This poster describes the requirements, the design and the realization of the WISDOM antenna system accommodated on the ExoMars rover. Simulated antenna performance and measured antenna parameters as well as preliminary antenna test measurements performed in the lab and in permafrost regions on earth will be discussed in this poster presentation. The main design requirements of the WISDOM antenna system are driven one hand by the required science

  6. Design and fabrication of low-cost reconfigurable microstrip antenna using photodiode as optical switching

    NASA Astrophysics Data System (ADS)

    Kusumawati, E. R.; Pramono, Y. H.; Rubiyanto, A.

    2014-09-01

    Design, fabrication, and characterization prototype of reconfigurable dipole microstrip antenna using photodiode as optical switching have been conducted in the Laboratory for Optical and Microwave Physics Department Faculty of ITS. This paper presents a new reconfigurable antenna design using photodiode as optical switching. In order to be optical switching, photodiode must be illuminated by optical source. The optical source used is Infrared with power 8 mW. Antenna is fabricated in FR-4 substrate which has 1.6 mm thick and 4.8 relative permittivity value. The dimension of the substrate is 131 mm × 21.5 mm × 1.6 mm. The structure of antenna is Coplanar Stripline (CPS) dipole. Measurement is conducted in two state. First state is photodiodes unilluminated Infrared and the second state is illuminated. The measurement result indicate that if condition is not illuminated by Infrared (OFF-state) antenna has resonance frequency of 2010 MHz and 2120 MHz. At frequency 2010 MHz, S11 value -35.7 dB and bandwidth 57 MHz, meanwhile at frequency 2120 MHz, S11 value -17.3 dB and bandwidth 42 MHz. Then if photodiode was illuminated by infrared (ON-state), antenna work at frequency 2007 MHz with S11 value -41.8 dB and bandwidth 61 MHz and 2113 MHz with S11 value -19.4 and bandwidth 47 MHz. There was frequency shifting from 2010 MHz to 2007 MHz and 2120 MHz to 2113 MHz of 5 MHz. At ON state, S11 value also was shifting. There was 6.1 dB and 2.1 dB. Bandwidth at ON-state is wider than OFF state. Microstrip antenna with a reconfigurable optical switching photodiode has several advantages. The advantages are more easily fabricated and the cost is relatively cheaper than the other techniques of optical switching.

  7. 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

  8. Design and analysis of a lightweight prestressed antenna back-up structure

    NASA Astrophysics Data System (ADS)

    Ma, Zengxiang; Yang, Dehua; Cheng, Jingquan

    2010-07-01

    The planned Square Kilometer Array (SKA) includes three thousand 15m antennas. The radio flux density from the sun is stronger, so that a solar array, such as Frequency-Agile Solar Radiotelescope (FASR) with hundreds of dishes can have smaller dish size. Therefore, light weight, low cost dish design is of vital importance. The reflecting surface supported by an antenna back-up structure, generally, should have an RMS surface error less than λ/20 (λ. is the operating wavelength). For resisting gravitational, wind, and ice-snow loadings, an antenna dish also requires reasonable mode frequencies. In this paper, different low cost small or medium back-up structure designs are discussed, including double-layer truss design and prestressed dish design. Based on discussion, an innovative light weight, prestressed back-up structure is proposed for small or medium aperture antennas. Example of a small 4.5m aperture dish design working below 3GHz is presented. This design is a one-layer prestressed truss structure with low weight, ease installation, and low manufacture cost. Structural analysis and modal extraction results show the structure is much stiffer than the same structure without prestressed loading.

  9. 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.

  10. 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.