Sample records for a2 icrh antennas

  1. Operations of the External Conjugate-T Matching System for the A2 ICRH Antennas at JET

    NASA Astrophysics Data System (ADS)

    Monakhov, I.; Graham, M.; Blackman, T.; Mayoral, M.-L.; Nightingale, M.; Sheikh, H.; Whitehurst, A.

    2009-11-01

    The External Conjugate-T (ECT) matching system was successfully commissioned on two A2 ICRH antennas at JET in 2009. The system allows trip-free injection of RF power into ELMy H-mode plasmas in the 32-52 MHz band without antenna phasing restrictions. The ECT demonstrates robust and predictable performance and high load-tolerance during routine operations, injecting up to 4 MW average power into H-mode plasma with Type-I ELMs. The total power coupled to ELMy plasma by all the A2 antennas using the ECT and 3dB systems has been increased to 7 MW. Antenna arcing during ELMs has been identified as a new challenge to high-power ICRH operations in H-mode plasma. The implemented Advanced Wave Amplitude Comparison System (AWACS) has proven to be an efficient protection tool for the ECT scheme.

  2. Operations of the External Conjugate-T Matching System for the A2 ICRH Antennas at JET

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Monakhov, I.; Graham, M.; Blackman, T.

    2009-11-26

    The External Conjugate-T (ECT) matching system was successfully commissioned on two A2 ICRH antennas at JET in 2009. The system allows trip-free injection of RF power into ELMy H-mode plasmas in the 32-52 MHz band without antenna phasing restrictions. The ECT demonstrates robust and predictable performance and high load-tolerance during routine operations, injecting up to 4 MW average power into H-mode plasma with Type-I ELMs. The total power coupled to ELMy plasma by all the A2 antennas using the ECT and 3dB systems has been increased to 7 MW. Antenna arcing during ELMs has been identified as a new challengemore » to high-power ICRH operations in H-mode plasma. The implemented Advanced Wave Amplitude Comparison System (AWACS) has proven to be an efficient protection tool for the ECT scheme.« less

  3. Modeling of the JET-EP ICRH antenna

    NASA Astrophysics Data System (ADS)

    Koch, R.; Amarante, G. S.; Heuraux, S.; Pécoul, S.; Louche, F.

    2001-10-01

    The new ICRH antenna planned for the Enhanced Performance phase of JET (JET-EP) is analyzed using the antenna coupling code ICANT, which self-consistently determines the currents on all antenna parts. This study addresses, using a simplified antenna model, the question of the impact on the coupling of the poloidal segmentation of the conductors, of their width and of their poloidal phasing. We also address the question of the relation between the imaginary part of the power computed by the code and the input impedance of the antenna. An example of current distribution on the complete antenna in vacuum is also shown.

  4. Progress in Arc Safety System Based on Harmonics Detection for ICRH Antennae

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berger-By, G.; Beaumont, B.; Lombard, G.

    2007-09-28

    The arc detection systems based on harmonics detection have been tested n USA (TFTR, DIII, Alcator C-mod) and Germany (Asdex). These systems have some advantages in comparison with traditonal securities which use a threshold on the Vr/Vf (Reflected to Forward voltage ratio) calculation and are ITER relevant. On Tore Supra (TS) 3 systems have been built using this principle with some improvements and new features to increase the protection of the 3 ICRH generators and antennae. On JET 2 arc safety systems based on the TS principle wil also be used to mprove the JET ITER-like antenna safety. In ordermore » to have the maximum security level on the TS ICRH system, the 3 antennae are used with these systems during all plasma shots n redundancy with the other systems. This TS RF principle and ts electronic interactions with the VME control of the generator are described. The results on the TS ICRH transmitter feeding the 3 antennae are summarized and some typical signals are given.« less

  5. ICRH antenna S-matrix measurements and plasma coupling characterisation at JET

    NASA Astrophysics Data System (ADS)

    Monakhov, I.; Jacquet, P.; Blackman, T.; Bobkov, V.; Dumortier, P.; Helou, W.; Lerche, E.; Kirov, K.; Milanesio, D.; Maggiora, R.; Noble, C.; Contributors, JET

    2018-04-01

    The paper is dedicated to the characterisation of multi-strap ICRH antenna coupling to plasma. Relevance of traditional concept of coupling resistance to antennas with mutually coupled straps is revised and the importance of antenna port excitation consistency for application of the concept is highlighted. A method of antenna S-matrix measurement in presence of plasma is discussed allowing deeper insight into the problem of antenna-plasma coupling. The method is based entirely on the RF plant hardware and control facilities available at JET and it involves application of variable phasing between the antenna straps during the RF plant operations at  >100 kW. Unlike traditional techniques relying on low-power (~10 mW) network analysers, the applied antenna voltage amplitudes are relevant to practical conditions of ICRH operations; crucially, they are high enough to minimise possible effects of antenna loading non-linearity due to the RF sheath effects and other phenomena which could affect low-power measurements. The method has been successfully applied at JET to conventional 4-port ICRH antennas energised at frequencies of 33 MHz, 42 MHz and 51 MHz during L-mode plasma discharges while different gas injection modules (GIMs) were used to maintain comparable plasma densities during the pulses. The S-matrix assessment and its subsequent processing yielding ‘global’ antenna coupling resistances in conditions of equalised port maximum voltages allowed consistent description of antenna coupling to plasma at different strap phasing, operational frequencies and applied GIMs. Comprehensive experimental characterisation of mutually coupled antenna straps in presence of plasma also provided a unique opportunity for in-depth verification of TOPICA computer simulations.

  6. Self-consistent computation of the electric field near ICRH antennas. Application to the Tore Supra antenna

    NASA Astrophysics Data System (ADS)

    Pécoul, S.; Heuraux, S.; Koch, R.; Leclert, G.; Bécoulet, A.; Colas, L.

    1999-09-01

    Self-consistent calculations of the 3D electric field patterns between the screen and the plasma have been made with the ICANT code for realistic antennas. Here we explain how the ICRH antennas of the Tore Supra tokamak are modelled.

  7. Self-consistent computation of the electric field near ICRH antennas. Application to the Tore Supra antenna

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pecoul, S.; Heuraux, S.; Koch, R.

    1999-09-20

    Self-consistent calculations of the 3D electric field patterns between the screen and the plasma have been made with the ICANT code for realistic antennas. Here we explain how the ICRH antennas of the Tore Supra tokamak are modelled.

  8. Thermal analysis and optimization of the EAST ICRH antenna

    NASA Astrophysics Data System (ADS)

    Qingxi, YANG; Wei, SONG; Qunshan, DU; Yuntao, SONG; Chengming, QIN; Xinjun, ZHANG; Yanping, ZHAO

    2018-02-01

    The ion cyclotron resonance of frequency heating (ICRH) plays an important role in plasma heating. Two ICRH antennas were designed and applied on the EAST tokamak. In order to meet the requirement imposed by high-power and long-pulse operation of EAST in the future, an active cooling system is mandatory to be designed to remove the heat load deposited on the components. Thermal analyses for high heat-load components have been carried out, which presented clear temperature distribution on each component and provided the reference data to do the optimization. Meanwhile, heat pipes were designed to satisfy the high requirement imposed by a Faraday shield and lateral limiter.

  9. Numerical modeling of the coupling of an ICRH antenna with a plasma with self-consistent antenna currents

    NASA Astrophysics Data System (ADS)

    Pécoul, S.; Heuraux, S.; Koch, R.; Leclert, G.

    2002-07-01

    A realistic modeling of ICRH antennas requires the knowledge of the antenna currents. The code ICANT determines self-consistently these currents and, as a byproduct, the electrical characteristics of the antenna (radiated power, propagation constants on straps, frequency response, … ). The formalism allows for the description of three-dimensional antenna elements (for instance, finite size thick screen blades). The results obtained for various cases where analytical results are available are discussed. The resonances appearing in the spectrum and the occurrence of unphysical resonant modes are discussed. The capability of this self-consistent method is illustrated by a number of examples, e.g., fully conducting thin or thick screen bars leading to magnetic shielding effects, frequency response and resonances of an end-tuned antenna, field distributions in front of a Tore-Supra type antenna with tilted screen blades.

  10. Design and operations of a load-tolerant external conjugate-T matching system for the A2 ICRH antennas at JET

    NASA Astrophysics Data System (ADS)

    Monakhov, I.; Graham, M.; Blackman, T.; Dowson, S.; Durodie, F.; Jacquet, P.; Lehmann, J.; Mayoral, M.-L.; Nightingale, M. P. S.; Noble, C.; Sheikh, H.; Vrancken, M.; Walden, A.; Whitehurst, A.; Wooldridge, E.; Contributors, JET-EFDA

    2013-08-01

    A load-tolerant external conjugate-T (ECT) impedance matching system for two A2 ion cyclotron resonance heating (ICRH) antennas was successfully put into operation at JET. The system allows continuous injection of the radio-frequency (RF) power into plasma in the presence of strong antenna loading perturbations caused by edge-localized modes (ELMs). Reliable ECT performance was demonstrated under a variety of antenna loading conditions including H-mode plasmas with radial outer gaps (ROGs) in the range 4-14 cm. The high resilience to ELMs predicted during the circuit simulations was fully confirmed experimentally. Dedicated arc-detection techniques and real-time matching algorithms were developed as a part of the ECT project. The new advanced wave amplitude comparison system has proven highly efficient in detection of arcs both between and during ELMs. The ECT system has allowed the delivery of up to 4 MW of RF power without trips into plasmas with type-I ELMs. Together with the 3 dB system and the ITER-like antenna, the ECT has brought the total RF power coupled to ELMy plasma to over 8 MW, considerably enhancing JET research capabilities. This paper provides an overview of the key design features of the ECT system and summarizes the main experimental results achieved so far.

  11. Prediction of plasma-facing ICRH antenna behavior via a Finite-Element solution of coupled Integral Equations

    NASA Astrophysics Data System (ADS)

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

    2005-09-01

    The demand for a predictive tool to help designing ICRH antennas for fusion experiments has driven the development of codes like ICANT, RANT3D, and the early developments and further upgrades of TOPICA code. Currently, TOPICA handles the actual geometry of ICRH antennas (with their housing, etc.) as well as a realistic plasma model, including density and temperature profiles and FLR effects. Both goals have been attained by formally splitting 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 writing a set of coupled integral equations for the unknown equivalent (current) sources; finite elements are used on a triangular-cell mesh and a linear system is obtained on application of the weighted-residual solution scheme. In the vacuum region calculations are done in the spatial domain, whereas in the plasma region a spectral (wavenumber) representation of fields and currents is adopted, thus allowing a description of the plasma by a surface impedance matrix. Thanks to this approach, any plasma model can be used in principle, and at present Brambilla's FELICE code has been employed. The natural outputs of TOPICA are the induced currents on the conductors 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. This paper is precisely devoted to the description of TOPICA, whereas examples of results for real-life antennas are reported in a companion paper [1] in this proceedings.

  12. Prediction of plasma-facing ICRH antenna behavior via a Finite-Element solution of coupled Integral Equations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lancellotti, V.; Milanesio, D.; Maggiora, R.

    2005-09-26

    The demand for a predictive tool to help designing ICRH antennas for fusion experiments has driven the development of codes like ICANT, RANT3D, and the early developments and further upgrades of TOPICA code. Currently, TOPICA handles the actual geometry of ICRH antennas (with their housing, etc.) as well as a realistic plasma model, including density and temperature profiles and FLR effects. Both goals have been attained by formally splitting 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 writing a set of coupled integralmore » equations for the unknown equivalent (current) sources; finite elements are used on a triangular-cell mesh and a linear system is obtained on application of the weighted-residual solution scheme. In the vacuum region calculations are done in the spatial domain, whereas in the plasma region a spectral (wavenumber) representation of fields and currents is adopted, thus allowing a description of the plasma by a surface impedance matrix. Thanks to this approach, any plasma model can be used in principle, and at present Brambilla's FELICE code has been employed. The natural outputs of TOPICA are the induced currents on the conductors 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. This paper is precisely devoted to the description of TOPICA, whereas examples of results for real-life antennas are reported in a companion paper in this proceedings.« less

  13. Improvements to the ICRH antenna time-domain 3D plasma simulation model

    NASA Astrophysics Data System (ADS)

    Smithe, David N.; Jenkins, Thomas G.; King, J. R.

    2015-12-01

    We present a summary of ongoing improvements to the 3D time-domain plasma modeling software that has been used to look at ICRH antennas on Alcator C-Mod, NSTX, and ITER [1]. Our past investigations have shown that in low density cases where the slow wave is propagating, strong amplitude lower hybrid resonant fields can occur. Such a scenario could result in significant parasitic power loss in the SOL. The primary resonance broadening in this case is likely collisions with neutral gas, and thus we are upgrading the model to include realistic neutral gas in the SOL, in order to provide a better understanding of energy balance in these situations. Related to this, we are adding a temporal variation capability to the local plasma density in front of the antenna in order to investigate whether the near fields of the antenna could modify the local density sufficiently to initiate a low density situation. We will start with a simple scalar ponderomotive potential density expulsion model [2] for the density evolution, but are also looking to eventually couple to a more complex fluid treatment that would include tensor pressures and convective physics and sources of neutrals and ionization. We also review continued benchmarking efforts, and ongoing and planned improvements to the computational algorithms, resulting from experience gained during our recent supercomputing runs on the Titan supercomputer, including GPU operations.

  14. Composite Materials and Meta Materials for a New Approach to ITER ICRH Loads

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bottollier-Curtet, H.; Argouarch, A.; Vulliez, K.

    Preliminary laboratory testing of ICRH antennas is a very useful step before their commissioning. Traditionally, pure water, salt water or baking soda water loads are used. These 'water' loads are convenient but strongly limited in terms of performance testing. We have started two feasibility studies for advanced ICRH loads made of ferroelectric ceramics (passive loads) and meta materials (active loads). Preliminary results are very encouraging.

  15. JET ICRH plant statistics from 2008-2012

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wooldridge, E.; Monakhov, I.; Blackman, T.

    2014-02-12

    JET ICRH plant faults from 2008 - 2012 have been catalogued and a new assessment of the reliability of the plant by sub-system is given. Data from pulses where ICRH was used, excluding the ITER-Like Antenna (ILA) and its generators, has been collated. This is compared to fault data in order to investigate any correlation between faults and operations. The number of faults is shown to have decreased between 2011-2012 in comparison to 2008-2009 as the time between faults is shown to have increased. Future electronic fault logging requirements to enable easier analysis are discussed. Due to the changing configurationmore » of the ICRH plant; the introduction of ELM tolerant systems, generator upgrade, changes to the settings of the VSWR protection et cetera, a method to expand the fault database to include more historical data [1] in a consistent way are discussed.« less

  16. Ion Cyclotron Resonant Heating (ICRH) system used on the Tandem Mirror Experiment-Upgrade (TMX-U)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ferguson, S.W.; Maxwell, T.M.; Antelman, D.R.

    1985-11-11

    Ion Cyclotron Resonant Heating (ICRH) is part of the plasma heating system used on the TMX-U experiment. Radio frequency (RF) energy is injected into the TMX-U plasma at a frequency near the fundamental ion resonance (2 to 5 MHz). The RF fields impart high velocities to the ions in a direction perpendicular to the TMX-U magnetic field. Particle collision then converts this perpendicular heating to uniform plasma heating. This paper describes the various aspects of the ICRH system: antennas, power supplies, computer control, and data acquisition. 4 refs., 10 figs.

  17. Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO

    NASA Astrophysics Data System (ADS)

    Ragona, R.; Messiaen, A.

    2016-07-01

    For the central heating of a fusion reactor ion cyclotron radio frequency heating (ICRH) is the first choice method as it is able to couple RF power to the ions without density limit. The drawback of this heating method is the problem of excitation of the magneto-sonic wave through the plasma boundary layer from the antenna located along the wall, without exceeding its voltage standoff. The amount of coupling depends on the antenna excitation and the surface admittance at the antenna output due to the plasma profile. The paper deals with the optimization of the antenna excitation by the use of sections of traveling-wave antennas (TWAs) distributed all along the reactor wall between the blanket modules. They are mounted and fed in resonant ring system(s). First, the physics of the coupling of a strap array is studied by simple models and the coupling code ANTITER II. Then, after the study of the basic properties of a TWA section, its feeding problem is solved by hybrids driving them in resonant ring circuit(s). The complete modeling is obtained from the matrices of the TWA sections connected to one of the feeding hybrid(s). The solution is iterated with the coupling code to determine the loading for a reference low-coupling ITER plasma profile. The resulting wave pattern up to the plasma bulk is derived. The proposed system is totally load resilient and allows us to obtain a very selective exciting wave spectrum. A discussion of some practical implementation problems is added.

  18. ICRH system performance during ITER-Like Wall operations at JET and the outlook for DT campaign

    NASA Astrophysics Data System (ADS)

    Monakhov, Igor; Blackman, Trevor; Dumortier, Pierre; Durodié, Frederic; Jacquet, Philippe; Lerche, Ernesto; Noble, Craig

    2017-10-01

    Performance of JET ICRH system since installation of the metal ITER-Like Wall (ILW) has been assessed statistically. The data demonstrate steady increase of the RF power coupled to plasmas over recent years with the maximum pulse-average and peak values exceeding respectively 6MW and 8MW in 2016. Analysis and extrapolation of power capabilities of conventional JET ICRH antennas is provided and key performance-limiting factors are discussed. The RF plant operational frequency options are presented highlighting the issues of efficient ICRH application within a foreseeable range of DT plasma scenarios.

  19. Experimental Study of Convective Cells and RF Sheaths Excited by a Fast Wave Antenna in the LAPD

    NASA Astrophysics Data System (ADS)

    Martin, Michael; Gekelman, Walter; Pribyl, Patrick; van Compernolle, Bart; Carter, Troy; van Eester, Dirk; Crombé, Kristel

    2016-10-01

    Ion cyclotron resonance heating (ICRH) will be essential for ITER where it is planned to couple 20 MW to the plasma. During ICRH, radio frequency (RF) sheaths may form on the antenna or farther away, and convective cells are suspected to form adjacent to ICRH antennas, negatively affecting both machine and plasma performance. The LAPD (ne 10 12 - 13cm-3 , Te 1-10 eV, B0 0.4 to 2 kG, diameter 60 cm, length 17m) is an ideal device for performing detailed experiments to fully diagnose these phenomena. A 200 kW RF system capable of pulsing at the 1 Hz. rep. rate of the LAPD and operating from 2 to 2.5 MHz has been constructed to perform such studies. B0 can be adjusted so that this encompasses the 1st to 7th harmonic of fci in H plasmas. Emissive, Mach, Langmuir, and B-field probes measured plasma potential, bulk plasma flows, wave patterns, ne, and Te in 2D planes at various axial locations from the antenna. Plasma potential enhancements of up to 90 V along magnetic field lines connected to the antenna and induced ExB flows consistent in structure with convective cells were observed. Details of these observations along with power scaling of RF sheath voltage and convective cell flows will be presented.

  20. Analysis of the phase control of the ITER ICRH antenna array. Influence on the load resilience and radiated power spectrum

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Messiaen, A., E-mail: a.messiaen@fz-juelich.de; Ongena, J.; Vervier, M.

    2015-12-10

    The paper analyses how the phasing of the ITER ICRH 24 strap array evolves from the power sources up to the strap currents of the antenna. The study of the phasing control and coherence through the feeding circuits with prematching and automatic matching and decoupling network is made by modeling starting from the TOPICA matrix of the antenna array for a low coupling plasma profile and for current drive phasing (worst case for mutual coupling effects). The main results of the analysis are: (i) the strap current amplitude is well controlled by the antinode V{sub max} amplitude of the feedingmore » lines, (ii) the best toroidal phasing control is done by the adjustment of the mean phase of V{sub max} of each poloidal straps column, (iii) with well adjusted system the largest strap current phasing error is ±20°, (iv) the effect on load resilience remains well below the maximum affordable VSWR of the generators, (v) the effect on the radiated power spectrum versus k{sub //} computed by means of the coupling code ANTITER II remains small for the considered cases.« less

  1. ICANT, a code for the self-consistent computation of ICRH antenna coupling

    NASA Astrophysics Data System (ADS)

    Pécoul, S.; Heuraux, S.; Koch, R.; Leclert, G.

    1996-02-01

    The code deals with 3D antenna structures (finite length antennae) that are used to launch electromagnetic waves into tokamak plasmas. The antenna radiation problem is solved using a finite boundary element technique combined with a spectral solution of the interior problem. The slab approximation is used, and periodicity in y and z directions is introduced to account for toroidal geometry. We present results for various types of antennae radiating in vacuum: antenna with a finite Faraday screen and ideal Faraday screen, antenna with side limiters and phased antenna arrays. The results (radiated power, current profile) obtained are very close to analytical solutions when available.

  2. ICANT, a code for the self-consistent computation of ICRH antenna coupling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pecoul, S.; Heuraux, S.; Koch, R.

    1996-02-01

    The code deals with 3D antenna structures (finite length antennae) that are used to launch electromagnetic waves into tokamak plasmas. The antenna radiation problem is solved using a finite boundary element technique combined with a spectral solution of the interior problem. The slab approximation is used, and periodicity in {ital y} and {ital z} directions is introduced to account for toroidal geometry. We present results for various types of antennae radiating in vacuum: antenna with a finite Faraday screen and ideal Faraday screen, antenna with side limiters and phased antenna arrays. The results (radiated power, current profile) obtained are verymore » close to analytical solutions when available. {copyright} {ital 1996 American Institute of Physics.}« less

  3. Estimates of RF-induced erosion at antenna-connected beryllium plasma-facing components in JET

    DOE PAGES

    Klepper, C. C.; Borodin, D.; Groth, M.; ...

    2016-01-18

    Radio-frequency (RF)-enhanced surface erosion of beryllium (Be) plasma-facing components is explored, for the first time, using the ERO code. We applied the code in order to measure the RF-enhanced edge Be line emission at JET Be outboard limiters, in the presence of high-power, ion cyclotronresonance heating (ICRH) in L-mode discharges. In this first modelling study, the RF sheath effect from an ICRH antenna on a magnetically connected, limiter region is simulated by adding a constant potential to the local sheath, in an attempt to match measured increases in local Be I and Be II emission of factors of 2 3.more » It was found that such increases are readily simulated with added potentials in the range of 100 200 V, which is compatible with expected values for potentials arising from rectification of sheath voltage oscillations from ICRH antennas in the scrape-off layer plasma. We also estimated absolute erosion values within the uncertainties in local plasma conditions.« less

  4. Experimental Study of RF Sheath Formation on a Fast Wave Antenna and Limiter in the LAPD

    NASA Astrophysics Data System (ADS)

    Martin, Michael; Gekelman, Walter; Pribyl, Patrick; van Compernolle, Bart; Carter, Troy

    2015-11-01

    Ion cyclotron resonance heating (ICRH) will be an essential component of heating power in ITER. During ICRH, radio frequency (RF) sheaths may form both at the exciting antenna and further away, e.g. in the divertor region, and may cause wall material sputtering and decreased RF power coupling to the plasma. It is important to do detailed laboratory experiments that fully diagnose the sheaths and wave fields. This is not possible in fusion devices. A new RF system has recently been constructed for performing such studies in the LAPD plasma column (ne ~1012 -1013cm-3 , Te ~ 1 - 10 eV ,B0 ~ 400 - 2000 G , diameter ~ 60cm , length ~ 18 m) . The RF system is capable of pulsing at the 1 Hz rep. rate of the LAPD plasma and operating between 2-6 MHz (1st - 9th harmonic of fci in H) with a power output of 200 kW. First results of this system driving a single-strap fast wave antenna will be presented. Emissive and Langmuir probe measurements in the vicinity of both the antenna and a remote limiter and wave coupling measured by magnetic pickup loops will be presented.

  5. Generation of multiple analog pulses with different duty cycles within VME control system for ICRH Aditya system

    NASA Astrophysics Data System (ADS)

    Joshi, Ramesh; Singh, Manoj; Jadav, H. M.; Misra, Kishor; Kulkarni, S. V.; ICRH-RF Group

    2010-02-01

    Ion Cyclotron Resonance Heating (ICRH) is a promising heating method for a fusion device due to its localized power deposition profile, a direct ion heating at high density, and established technology for high RF power generation and transmission at low cost. Multiple analog pulse with different duty cycle in master of digital pulse for Data acquisition and Control system for steady state RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya to produce pre ionization and second analog pulse will produce heating. The control system software is based upon single digital pulse operation for RF source. It is planned to integrate multiple analog pulses with different duty cycle in master of digital pulse for Data acquisition and Control system for RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya tokamak. The task of RF ICRH DAC is to control and acquisition of all ICRH system operation with all control loop and acquisition for post analysis of data with java based tool. For pre ionization startup as well as heating experiments using multiple RF Power of different powers and duration. The experiment based upon the idea of using single RF generator to energize antenna inside the tokamak to radiate power twise, out of which first analog pulse will produce pre ionization and second analog pulse will produce heating. The whole system is based on standard client server technology using tcp/ip protocol. DAC Software is based on linux operating system for highly reliable, secure and stable system operation in failsafe manner. Client system is based on tcl/tk like toolkit for user interface with c/c++ like environment which is reliable programming languages widely used on stand alone system operation with server as vxWorks real time operating system like environment. The paper is focused on the Data acquisition and monitoring system software on Aditya RF ICRH System with analog pulses in slave mode with digital pulse in

  6. Study of the choice of the decoupling layout for the ITER ICRH system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vervier, M., E-mail: michel.vervier@rma.ac.be; Messiaen, A.; Ongena, J.

    10 decouplers are used to neutralize the mutual coupling effects and to control the current amplitude of the 24 straps array of the ITER ICRH antenna in the case of current drive phasing. In the case of heating phasing only 4 decouplers are active and the array current control needs to act on the ratio between the power delivered by the 4 generators. This ratio is very sensitive to the precise adjustment of the antenna array phasing. The maximum total radiated power capability is then limited when the power of one generator reaches its maximum value. With the addition ofmore » four switches all 10 installed decouplers are made active and can act on all mutual coupling effects with equal source power from the 4 generators. With four more switches the current drive phasing could work with a reduced poloidal phasing resulting in a 35% increase of its coupling to the plasma.« less

  7. Developments for the ICRH System of the Ignitor Machine

    NASA Astrophysics Data System (ADS)

    Sassi, M.; Mantovani, S.; Coppi, B.

    2014-10-01

    The ICRH system that is suitable for the high-density plasmas to be produced by the Ignitor machine has been designed and components of it have been tested. This system will operate over the range 80-120 MHz, consistently with magnetic fields in the range 9-13 T. The maximum delivered power is in the interval 8 MW (at 80 MHz) to 6 MW (at 120 MHz) distributed over 4 ports. A full size prototype of the VTL between the port flange and the antenna straps, with the external support and precise guiding system has been constructed. The innovative quick latching system located at the end of the coaxial cable has been successfully tested, providing perfect interference with the spring Be-Cu electrical contacts. Vacuum levels of 10-6, compatible with the limit of material degassing, and electrical tests up to 12 kV without discharges have been obtained. Sponsored in part by the US DOE.

  8. Evidence of 9Be  +  p nuclear reactions during 2ω CH and hydrogen minority ICRH in JET-ILW hydrogen and deuterium plasmas

    NASA Astrophysics Data System (ADS)

    Krasilnikov, A. V.; Kiptily, V.; Lerche, E.; Van Eester, D.; Afanasyev, V. I.; Giroud, C.; Goloborodko, V.; Hellesen, C.; Popovichev, S. V.; Mironov, M. I.; contributors, JET

    2018-02-01

    The intensity of 9Be  +  p nuclear fusion reactions was experimentally studied during second harmonic (2ω CH) ion-cyclotron resonance heating (ICRH) and further analyzed during fundamental hydrogen minority ICRH of JET-ILW hydrogen and deuterium plasmas. In relatively low-density plasmas with a high ICRH power, a population of fast H+ ions was created and measured by neutral particle analyzers. Primary and secondary nuclear reaction products, due to 9Be  +  p interaction, were observed with fast ion loss detectors, γ-ray spectrometers and neutron flux monitors and spectrometers. The possibility of using 9Be(p, d)2α and 9Be(p, α)6Li nuclear reactions to create a population of fast alpha particles and study their behaviour in non-active stage of ITER operation is discussed in the paper.

  9. Construction of a Full-size Component of the ICRH System

    NASA Astrophysics Data System (ADS)

    Mantovani, S.; Sassi, M.; Coppi, B.

    2012-10-01

    The ICRH system is an important component of the Ignitor project and all efforts have been made to ensure that its design takes into account the construction experience gained in the most advanced laboratories. The system is designed to operate over a frequency range 80-120 MHz, which is consistent with the use of magnetic fields in the range 9-13 T. The maximum delivered power ranges from 8 MW (at 80 MHz) to 6 MW (at 120 MHz) distributed over 4 ports. Since the transition from a detailed design to the actual construction is not without surprises we have constructed a full size prototype of the VTL between the port flange and the antenna straps, with the external support and precise guiding system. The innovative quick latching system located at the end of the coaxial cable was successfully tested, providing perfect interference with the spring Be-Cu electrical contacts. Special care was given to the finishing of the inox surfaces, and to the TIG welds. Vacuum levels of 10-6, compatible with the limit of material degassing, and electrical tests up to 12 kV without discharges have been obtained. A revision of the other key components of the Ignitor machine has been undertaken, taking into account the experience gained in the fabrication of the corresponding prototypes.

  10. Estimates of RF-Induced Erosion at Antenna-Connected Beryllium Plasma-Facing Components in JET

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Borodin, D.; Groth, M.; Airila, M.

    2016-01-01

    During high-power, ion cyclotron resonance heating (ICRH), RF sheath rectification and RF induced plasma-wall interactions (RF-PWI) can potentially limit long-pulse operation. With toroidally-spaced ICRH antennas, in an ITER-like wall (ILW) environment, JET provides an ideal environment for ITER-relevant, RF-PWI studies. JET pulses combining sequential toggling of the antennas with q95 (edge safety factor) sweeping were recently used to localize RF-enhanced Be I and Be II spectral line emission at outboard poloidal (beryllium) limiters. These measurements were carried out in the early stages of JET-ILW and in ICRF-only, L-mode discharges. The appearance of enhanced emission spots was explained by their magneticmore » connection to regions of ICRH antennas associated with higher RF-sheath rectification [1]. The measured emission lines were the same as those already qualified in ERO modelling of inboard limiter beryllium erosion in JET limiter plasmas [2]. In the present work, we revisit this spectroscopic study with the focus on obtaining estimates of the impact of these RF-PWI on sputtering and on net erosion of the affected limiter regions. To do this, the ERO erosion and re-deposition code [2] is deployed with the detailed geometry of a JET outboard limiter. The effect of RF-PWI on sputtering is represented by varying the surface negative biasing, which affects the incidence energy and the resulting sputtering yield. The observed variations in line emission, from [1], for JET pulse 81173 of about factor 3 can be reproduced with ~ 100 200 V bias. ERO simulations show that the influence of the respective E-field on the local Be transport is localized near the surface and relatively small. Still, the distribution of the 3D plasma parameters, shadowing and other geometrical effects are quite important. The plasma parameter simulated by Edge2D-EIRENE [3] are extrapolated towards the surface and mapped in 3D. These initial modelling results are consistent with the

  11. Physics and technology in the ion-cyclotron range of frequency on Tore Supra and TITAN test facility: implication for ITER

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Litaudon, X; Bernard, J. M.; Colas, L.

    2013-01-01

    To support the design of an ITER ion-cyclotron range of frequency heating (ICRH) system and to mitigate risks of operation in ITER, CEA has initiated an ambitious Research & Development program accompanied by experiments on Tore Supra or test-bed facility together with a significant modelling effort. The paper summarizes the recent results in the following areas: Comprehensive characterization (experiments and modelling) of a new Faraday screen concept tested on the Tore Supra antenna. A new model is developed for calculating the ICRH sheath rectification at the antenna vicinity. The model is applied to calculate the local heat flux on Toremore » Supra and ITER ICRH antennas. Full-wave modelling of ITER ICRH heating and current drive scenarios with the EVE code. With 20 MW of power, a current of 400 kA could be driven on axis in the DT scenario. Comparison between DT and DT(3He) scenario is given for heating and current drive efficiencies. First operation of CW test-bed facility, TITAN, designed for ITER ICRH components testing and could host up to a quarter of an ITER antenna. R&D of high permittivity materials to improve load of test facilities to better simulate ITER plasma antenna loading conditions.« less

  12. View of Antenna #1 (foreground), and Antenna #2 surface doors. ...

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

    View of Antenna #1 (foreground), and Antenna #2 surface doors. Orientation Target #2 in background. Image looking northeast - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

  13. View of Antenna #1 (foreground), and Antenna #2 surface doors. ...

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

    View of Antenna #1 (foreground), and Antenna #2 surface doors. Image looking northeast - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

  14. View of Antenna #2 (foreground), and Antenna #1 surface doors. ...

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

    View of Antenna #2 (foreground), and Antenna #1 surface doors. Orientation Target #1 in background. Image looking northwest - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

  15. Development of long-pulse heating & current drive actuators & operational techniques compatible with a high-Z divertor & first wall

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tynan, George

    This was a collaboration between UCSD and MIT to study the effective application of ion-cyclotron heating (ICRH) on the EAST tokamak, located in China. The original goal was for UCSD to develop a diagnostic that would allow measurement of the steady state, or DC, convection pattern that develops on magnetic field lines that attach or connect to the ICRH antenna. This diagnostic would then be used to develop techniques and approaches that minimize or even eliminate such DC convection during application of strong ICRH heating. This was thought to then indicate reduction or elimination of parasitic losses of heating power,more » and thus be an indicator of effective RF heating. The original plan to use high speed digital gas-puff imaging (GPI) of the antenna-edge plasma region in EAST was ultimately unsuccessful due to limitations in machine and camera operations. We then decided to attempt the same experiment on the ALCATOR C-MOD tokamak at MIT which had a similar instrument already installed. This effort was ultimately successful, and demonstrated that the underlying idea of using GPI as a diagnostic for ICRH antenna physics would, in fact, work. The two-dimensional velocity fields of the turbulent structures, which are advected by RF-induced E x B flows, are obtained via the time-delay estimation (TDE) techniques. Both the magnitude and radial extension of the radial electric field E-r were observed to increase with the toroidal magnetic field strength B and the ICRF power. The TDE estimations of RF-induced plasma potentials are consistent with previous results based on the probe measurements of poloidal phase velocity. The results suggest that effective ICRH heating with reduced impurity production is possible when the antenna/box system is designed so as to reduce the RF-induced image currents that flow in the grounded conducting antenna frame elements that surround the RF antenna current straps.« less

  16. Modelling of radio frequency sheath and fast wave coupling on the realistic ion cyclotron resonant antenna surroundings and the outer wall

    NASA Astrophysics Data System (ADS)

    Lu, L.; Colas, L.; Jacquot, J.; Després, B.; Heuraux, S.; Faudot, E.; Van Eester, D.; Crombé, K.; Křivská, A.; Noterdaeme, J.-M.; Helou, W.; Hillairet, J.

    2018-03-01

    In order to model the sheath rectification in a realistic geometry over the size of ion cyclotron resonant heating (ICRH) antennas, the self-consistent sheaths and waves for ICH (SSWICH) code couples self-consistently the RF wave propagation and the DC SOL biasing via nonlinear RF and DC sheath boundary conditions applied at plasma/wall interfaces. A first version of SSWICH had 2D (toroidal and radial) geometry, rectangular walls either normal or parallel to the confinement magnetic field B 0 and only included the evanescent slow wave (SW) excited parasitically by the ICRH antenna. The main wave for plasma heating, the fast wave (FW) plays no role on the sheath excitation in this version. A new version of the code, 2D SSWICH-full wave, was developed based on the COMSOL software, to accommodate full RF field polarization and shaped walls tilted with respect to B 0 . SSWICH-full wave simulations have shown the mode conversion of FW into SW occurring at the sharp corners where the boundary shape varies rapidly. It has also evidenced ‘far-field’ sheath oscillations appearing at the shaped walls with a relatively long magnetic connection length to the antenna, that are only accessible to the propagating FW. Joint simulation, conducted by SSWICH-full wave within a multi-2D approach excited using the 3D wave coupling code (RAPLICASOL), has recovered the double-hump poloidal structure measured in the experimental temperature and potential maps when only the SW is modelled. The FW contribution on the potential poloidal structure seems to be affected by the 3D effects, which was ignored in the current stage. Finally, SSWICH-full wave simulation revealed the left-right asymmetry that has been observed extensively in the unbalanced strap feeding experiments, suggesting that the spatial proximity effects in RF sheath excitation, studied for SW only previously, is still important in the vicinity of the wave launcher under full wave polarizations.

  17. Electric Fields near RF Heating and Current Drive Antennas in Tore Supra Measured with Dynamic Stark Effect Spectroscopy*

    NASA Astrophysics Data System (ADS)

    Klepper, C. C.; Martin, E. H.; Isler, R. C.; Colas, L.; Hillairet, J.; Marandet, Y.; Lotte, Ph.; Colledani, G.; Martin, V.; Hillis, D. L.; Harris, J. H.; Saoutic, B.

    2011-10-01

    Computational models of the interaction between RF waves and the scrape-off layer plasma near ion cyclotron resonant heating (ICRH) and lower hybrid current drive launch antennas are continuously improving. These models mainly predict the RF electric fields produced in the SOL and, therefore, the best measurement for verification of these models would be a direct measurement of these electric fields. Both types of launch antennas are used on Tore Supra and are designed for high power (up to 4MW/antenna) and long pulse (> > 25s) operation. Direct, non-intrusive measurement of the RF electric fields in the vicinity of these structures is achieved by fitting spectral profiles of deuterium Balmer-alpha and Balmer-beta to a model that includes the dynamic, external-field Stark effect, as well as Zeeman splitting and Doppler broadening mechanisms. The measurements are compared to the mentioned, near-field region, RF antenna models. *Work supported in part by the US DOE under Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC.

  18. Development of Data Acquisition Card Driver for ICRH System on EAST

    NASA Astrophysics Data System (ADS)

    Liu, Daming; Luo, Jiarong; Zhao, Yanping; Qin, Chengming

    2008-04-01

    Presented in this paper is the development of the driver for the data acquisition card with a peripheral component interconnection (PCI) local bus on the ion cyclotron range of frequency heating (ICRH) system. The driver is mainly aimed at the embedded VxWorks system (real-time operating system) which is widely used in various fields of real-time systems. An efficient way is employed to develop this driver, which will advance the real-time control of the ICRH system on the experimental advanced superconductor tokamak (EAST). The driver is designed using the TORNADO integrated development environment (IDE), and implemented in C plus language. The details include the hardware configuration, analogue/digital (A/D) and digital/analogue (D/A) conversion, input and output (I/O) operation of the driver to support over five cards. The data acquisition card can be manipulated in a low-level program and meet the requirements of A/D conversion and D/A outputs.

  19. Study of the effects of corrugated wall structures due to blanket modules around ICRH antennas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dumortier, Pierre; Louche, Fabrice; Messiaen, André

    2014-02-12

    In future fusion reactors, and in ITER, the first wall will be covered by blanket modules. 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, whichmore » could lead to large voltages in the gaps between the blanket modules and perturb the RF properties of the antenna if they are in the ICRF operating range. The effect on the wave propagation along the wall structure, which is acting as a spatially periodic (toroidally and poloidally) corrugated structure, and hence constitutes a slow wave structure modifying the wall boundary condition, is examined.« less

  20. A True Metasurface Antenna.

    PubMed

    El Badawe, Mohamed; Almoneef, Thamer S; Ramahi, Omar M

    2016-01-13

    We present a true metasurface antenna based on electrically-small resonators. The resonators are placed on a flat surface and connected to one feed point using corporate feed. Unlike conventional array antennas where the distance between adjacent antennas is half wavelength to reduce mutual coupling between adjacent antennas, here the distance between the radiating elements is electrically very small to affect good impedance matching of each resonator to its feed. A metasurface antenna measuring 1.2λ × 1.2λ and designed to operate at 3 GHz achieved a gain of 12 dBi. A prototype was fabricated and tested showing good agreement between numerical simulations and experimental results. Through numerical simulation, we show that the metasurface antenna has the ability to provide beam steering by phasing all the resonators appropriately.

  1. CPW-fed wearable antenna at 2.4 GHz ISM band

    NASA Astrophysics Data System (ADS)

    Muhammad, Zuraidah; Shah, S. M.; Abidin, Z. Z.; Asyhap, Adel Y. I.; Mustam, S. M.; Ma, Y.

    2017-09-01

    A wearable antenna working in 2.4 GHz for Industrial, Scientific and Medical (ISM) radio bands is presented in this work. The proposed antenna is a rectangular textile antenna with a coplanar waveguide (CPW) feeding on a cotton jeans as the substrate material. The antenna has a compact size with dimensions of 30 × 30 mm2 which makes it an attractive solution in a wearable antenna construction. The linear characteristics of the antenna are investigated to evaluate the performance of the antenna. The simulation and measurements results are compared and they agree well with each other.

  2. High Power Electric Propulsion Using The VASIMR VX-200: A Flight Technology Prototype

    NASA Astrophysics Data System (ADS)

    Bering, Edgar, III; Longmier, Benjamin; Glover, Tim; Chang-Diaz, Franklin; Squire, Jared; Brukardt, Michael

    2008-11-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high power magnetoplasma rocket, capable of Isp/thrust modulation at constant power. The plasma is produced by a helicon discharge. The bulk of the energy is added by ion cyclotron resonance heating (ICRH.) Axial momentum is obtained by adiabatic expansion of the plasma in a magnetic nozzle. Thrust/specific impulse ratio control in the VASIMR is primarily achieved by the partitioning of the RF power to the helicon and ICRH systems, with the proper adjustment of the propellant flow. Ion dynamics in the exhaust were studied using probes, gridded energy analyzers (RPA's), microwave interferometry and optical techniques. Results are summarize from high power ICRH experiments performed on the VX-100 using argon plasma during 2007, and on the VX-200 using argon plasma during 2008. The VX-100 has demonstrated ICRH antenna efficiency >90% and a total coupling efficiency of ˜75%. The rocket performance parameters inferred by integrating the moments of the ion energy distribution corresponds to a thrust of 2 N at an exhaust velocity of 20 km/s with the VX-100 device. The new VX-200 machine is described.

  3. 47 CFR 2.1051 - Measurements required: Spurious emissions at antenna terminals.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... antenna terminals. 2.1051 Section 2.1051 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... Procedures Certification § 2.1051 Measurements required: Spurious emissions at antenna terminals. The radio... checked at the equipment output terminals when properly loaded with a suitable artificial antenna. Curves...

  4. 47 CFR 2.1051 - Measurements required: Spurious emissions at antenna terminals.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... antenna terminals. 2.1051 Section 2.1051 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... Procedures Certification § 2.1051 Measurements required: Spurious emissions at antenna terminals. The radio... checked at the equipment output terminals when properly loaded with a suitable artificial antenna. Curves...

  5. 47 CFR 2.1051 - Measurements required: Spurious emissions at antenna terminals.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... antenna terminals. 2.1051 Section 2.1051 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... Procedures Certification § 2.1051 Measurements required: Spurious emissions at antenna terminals. The radio... checked at the equipment output terminals when properly loaded with a suitable artificial antenna. Curves...

  6. 47 CFR 2.1051 - Measurements required: Spurious emissions at antenna terminals.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... antenna terminals. 2.1051 Section 2.1051 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... Procedures Certification § 2.1051 Measurements required: Spurious emissions at antenna terminals. The radio... checked at the equipment output terminals when properly loaded with a suitable artificial antenna. Curves...

  7. 47 CFR 2.1051 - Measurements required: Spurious emissions at antenna terminals.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... antenna terminals. 2.1051 Section 2.1051 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... Procedures Certification § 2.1051 Measurements required: Spurious emissions at antenna terminals. The radio... checked at the equipment output terminals when properly loaded with a suitable artificial antenna. Curves...

  8. X-Antenna: A graphical interface for antenna analysis codes

    NASA Technical Reports Server (NTRS)

    Goldstein, B. L.; Newman, E. H.; Shamansky, H. T.

    1995-01-01

    This report serves as the user's manual for the X-Antenna code. X-Antenna is intended to simplify the analysis of antennas by giving the user graphical interfaces in which to enter all relevant antenna and analysis code data. Essentially, X-Antenna creates a Motif interface to the user's antenna analysis codes. A command-file allows new antennas and codes to be added to the application. The menu system and graphical interface screens are created dynamically to conform to the data in the command-file. Antenna data can be saved and retrieved from disk. X-Antenna checks all antenna and code values to ensure they are of the correct type, writes an output file, and runs the appropriate antenna analysis code. Volumetric pattern data may be viewed in 3D space with an external viewer run directly from the application. Currently, X-Antenna includes analysis codes for thin wire antennas (dipoles, loops, and helices), rectangular microstrip antennas, and thin slot antennas.

  9. Use of a 2.3-GHz traveling-wave maser on the Usuda 64-meter antenna

    NASA Technical Reports Server (NTRS)

    Neff, D.

    1987-01-01

    A 2.3 GHz traveling-wave maser/closed-cycle refrigeration system was installed on the 64 m antenna at Usuda, Japan. This was done to evaluate the beam-waveguide antenna noise performance, and to support the International Cometary Explorer's (ICE's) comet flyby mission. System noise temperature at 2270 MHz was measured to be 15 K, including the maser noise contribution of 2.5 K. Maser installation and noise performance are described. The Usuda 64 m antenna is of high quality with a system operating noise temperature better than the DSN 64 m antennas.

  10. On efficiency and interpretation of sawteeth pacing with on-axis ICRH modulation in JET

    NASA Astrophysics Data System (ADS)

    Murari, A.; Craciunescu, T.; Peluso, E.; Lerche, E.; Gelfusa, M.; Contributors, JET

    2017-12-01

    In metallic machines ICRH heating is playing an increasingly important role. One of its most recent applications on the Joint Europena Torus (JET) is sawtooth control by ICRH modulation, for avoiding triggering dangerous neo-classical tearing modes (NTMs) and counteracting impurity accumulation. Some of the main difficulties of these experiments are the assessment of the synchronization efficiency and the understanding of the main physical mechanisms at play. In this paper, three independent classes of statistical indicators are introduced to address these issues: Recurrence Plots, Convergent Cross Mapping and Transfer Entropy. The application to JET experiments with the ILW shows that the proposed indicators agree quite well among themselves and provide sound estimates of the efficiency of the synchronisation scheme investigated. They also support, with a shot to shot basis analysis and an estimate of the uncertainties, the interpretation that the fast ions play a fundamental role in the stabilization of the sawteeth, in both L and H mode. Proposals for experiments to be carried out in the future to consolidate the interpretation of the results are discussed.

  11. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Performance Verification Report: Antenna Drive Subsystem METSAT AMSU-A2 (PN:1331200-2, SN:108)

    NASA Technical Reports Server (NTRS)

    Haapala, C.

    1999-01-01

    This is the Performance Verification Report, Antenna Drive Subassembly, Antenna Drive Subsystem, METSAT AMSU-A2 (P/N 1331200-2, SN: 108), for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  12. Turbulent transport stabilization by ICRH minority fast ions in low rotating JET ILW L-mode plasmas

    NASA Astrophysics Data System (ADS)

    Bonanomi, N.; Mantica, P.; Di Siena, A.; Delabie, E.; Giroud, C.; Johnson, T.; Lerche, E.; Menmuir, S.; Tsalas, M.; Van Eester, D.; Contributors, JET

    2018-05-01

    The first experimental demonstration that fast ion induced stabilization of thermal turbulent transport takes place also at low values of plasma toroidal rotation has been obtained in JET ILW (ITER-like wall) L-mode plasmas with high (3He)-D ICRH (ion cyclotron resonance heating) power. A reduction of the gyro-Bohm normalized ion heat flux and higher values of the normalized ion temperature gradient have been observed at high ICRH power and low NBI (neutral beam injection) power and plasma rotation. Gyrokinetic simulations indicate that ITG (ion temperature gradient) turbulence stabilization induced by the presence of high-energetic 3He ions is the key mechanism in order to explain the experimental observations. Two main mechanisms have been identified to be responsible for the turbulence stabilization: a linear electrostatic wave-fast particle resonance mechanism and a nonlinear electromagnetic mechanism. The dependence of the stabilization on the 3He distribution function has also been studied.

  13. A tunable microwave slot antenna based on graphene

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dragoman, Mircea; Aldrigo, Martino; Vasilache, D.

    The paper presents the experimental and modeling results of a microwave slot antenna in a coplanar configuration based on graphene. The antennas are fabricated on a 4 in. high-resistivity Si wafer, with a ∼300 nm SiO{sub 2} layer grown through thermal oxidation. A CVD grown graphene layer is transferred on the SiO{sub 2}. The paper shows that the reflection parameter of the antenna can be tuned by a DC voltage. 2D radiation patterns at various frequencies in the X band (8–12 GHz) are then presented using as antenna backside a microwave absorbent and a metalized surface. Although the radiation efficiency is lower thanmore » a metallic antenna, the graphene antenna is a wideband antenna while the metal antennas with the same geometry and working at the same frequencies are narrowband.« less

  14. ERO modeling and sensitivity analysis of locally enhanced beryllium erosion by magnetically connected antennas

    NASA Astrophysics Data System (ADS)

    Lasa, A.; Borodin, D.; Canik, J. M.; Klepper, C. C.; Groth, M.; Kirschner, A.; Airila, M. I.; Borodkina, I.; Ding, R.; Contributors, JET

    2018-01-01

    Experiments at JET showed locally enhanced, asymmetric beryllium (Be) erosion at outer wall limiters when magnetically connected ICRH antennas were in operation. A first modeling effort using the 3D erosion and scrape-off layer impurity transport modeling code ERO reproduced qualitatively the experimental outcome. However, local plasma parameters—in particular when 3D distributions are of interest—can be difficult to determine from available diagnostics and so erosion / impurity transport modeling input relies on output from other codes and simplified models, increasing uncertainties in the outcome. In the present contribution, we introduce and evaluate the impact of improved models and parameters with largest uncertainties of processes that impact impurity production and transport across the scrape-off layer, when simulated in ERO: (i) the magnetic geometry has been revised, for affecting the separatrix position (located 50-60 mm away from limiter surface) and thus the background plasma profiles; (ii) connection lengths between components, which lead to shadowing of ion fluxes, are also affected by the magnetic configuration; (iii) anomalous transport of ionized impurities, defined by the perpendicular diffusion coefficient, has been revisited; (iv) erosion yields that account for energy and angular distributions of background plasma ions under the present enhanced sheath potential and oblique magnetic field, have been introduced; (v) the effect of additional erosion sources, such as charge-exchange neutral fluxes, which are dominant in recessed areas like antennas, has been evaluated; (vi) chemically assisted release of Be in molecular form has been included. Sensitivity analysis highlights a qualitative effect (i.e. change in emission patterns) of magnetic shadowing, anomalous diffusion, and inclusion of neutral fluxes and molecular release of Be. The separatrix location, and energy and angular distribution of background plasma fluxes impact erosion

  15. Deployable antenna phase A study

    NASA Technical Reports Server (NTRS)

    Schultz, J.; Bernstein, J.; Fischer, G.; Jacobson, G.; Kadar, I.; Marshall, R.; Pflugel, G.; Valentine, J.

    1979-01-01

    Applications for large deployable antennas were re-examined, flight demonstration objectives were defined, the flight article (antenna) was preliminarily designed, and the flight program and ground development program, including the support equipment, were defined for a proposed space transportation system flight experiment to demonstrate a large (50 to 200 meter) deployable antenna system. Tasks described include: (1) performance requirements analysis; (2) system design and definition; (3) orbital operations analysis; and (4) programmatic analysis.

  16. Development of pre pre-driver amplifier stage for generator of SST-1 ICRH system

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Sinh Makwana, Azad; Srinivas, Y. S. S.; Kulkarni, S. V.; ICRH-RF Group

    2010-02-01

    The Ion Cyclotron Resonance Heating (ICRH) system for SST1 consists mainly of the cwrf power generator to deliver 1.5MW for 1000sec duration at the frequencies 22.8, 24.3 and 45.6±1MHz, the transmission line and the antenna. This is planned to develop a independent and dedicated cwrf generator that consists of a oscillator, buffer, rf switch, modulator, rf attenuator, directional coupler, three stage solid state low power amplifier and four stage triode & tetrode based high power amplifier with specific performance at 45.6±1MHz including frequencies 22.8 and 24.3±1MHz. The pre pre-driver high power amplifier stage is fabricated about triode 3CX3000A7. The tube has sufficient margin in terms of plate dissipation and grid dissipation that makes it suitable to withstand momentarily load mismatch and to upgrade the source in terms of output power later. This indigenously developed amplifier is integrated inside a radiation resistant rack with all required biasing power supplies, cooling blower, controls, monitors and interlocks for manual or remote control operation. This grounded grid mode amplifier will be operated at plate with 3.8KV/ 800mA in class AB for 1.8KW cwrf output power rating. The input circuit is broadband and the output circuit is tunable with slide variable inductor and a vacuum variable capacitor in the frequency range of 22.8 to 45.6MHz. It is designed for a gain of about 12dB, fabrication completed and undergoing cwrf power testing. This paper presents specifications, design criteria, circuit used, operating parameters, tests conducted and the results obtained.

  17. Miniaturized Pi (Π) - Slit monopole antenna for 2.4/5.2/5.8 applications

    NASA Astrophysics Data System (ADS)

    Chandan, Bharti, Gagandeep; Bharti, Pradutt Kumar; Rai, B. S.

    2018-04-01

    In present paper, two - shaped slots are inserted in a rectangular patch of a monopole antenna for dual band operation. The antenna design is very simple, compact and light weight with overall dimension 29×38×0.8 mm3. Prototype of the proposed antenna is constructed and tested to verify its usefulness for 2.4/5.2/5.8 ghz wlan/wimax applications. It has been observed that both simulated and measured results have good agreement and measured peak gain and radiation pattern are suitable as per the need of application.

  18. View of antenna tunnel end. Right to Antenna Silo #1, ...

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

    View of antenna tunnel end. Right to Antenna Silo #1, left to Antenna Silo #2 - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

  19. A Compact Annular Ring Microstrip Antenna for WSN Applications

    PubMed Central

    Wang, Daihua; Song, Linli; Zhou, Hanchang; Zhang, Zhijie

    2012-01-01

    A compact annular ring microstrip antenna was proposed for a wireless sensor network (WSN) application in the 2.4 GHz band. In this paper the major considerations of the conformal antenna design were the compact size and the impact on antenna's performance of a steel installation base. By using a chip resistor of large resistance (120 Ω) the antenna size was reduced to 38% of that a conventional annular ring patch antenna. With the addition of the steel installation base the resonant frequency of the antenna increases about 4.2% and the bandwidth reduces from 17.5% to 11.7% by adjusting the load resistance simultaneously. Several key parameters were discussed and optimized, and the antenna was fabricated and its performance measured. The antenna is well matched at 2.4 GHz with 34.2 dB return loss and –2.5 dBi peak gain. Meanwhile, it exhibits excellent radiation patterns with very low cross-polarization levels. PMID:23012510

  20. A compact annular ring microstrip antenna for WSN applications.

    PubMed

    Wang, Daihua; Song, Linli; Zhou, Hanchang; Zhang, Zhijie

    2012-01-01

    A compact annular ring microstrip antenna was proposed for a wireless sensor network (WSN) application in the 2.4 GHz band. In this paper the major considerations of the conformal antenna design were the compact size and the impact on antenna's performance of a steel installation base. By using a chip resistor of large resistance (120 Ω) the antenna size was reduced to 38% of that a conventional annular ring patch antenna. With the addition of the steel installation base the resonant frequency of the antenna increases about 4.2% and the bandwidth reduces from 17.5% to 11.7% by adjusting the load resistance simultaneously. Several key parameters were discussed and optimized, and the antenna was fabricated and its performance measured. The antenna is well matched at 2.4 GHz with 34.2 dB return loss and -2.5 dBi peak gain. Meanwhile, it exhibits excellent radiation patterns with very low cross-polarization levels.

  1. The principles of radio engineering and antennas. II Antennas (2nd revised and enlarged edition)

    NASA Astrophysics Data System (ADS)

    Belotserkovskii, G. B.

    This book represents the second part of a textbook for technical schools. The characteristics and parameters of antennas are considered along with transmission lines, the theory of single dipoles and radiator systems, and the technological realization of elements and units of the antenna-feeder system, taking into account filters and multiport networks for microwave communications applications, and ferrite circulators and isolators. The first edition of this textbook was published in 1969. For the current edition, the material in the first edition has been revised, and new material has been introduced. Much attention is given to microwave antennas, including, in particular, arrays with electrical scanning characteristics. Other topics discussed are related to the general principles of antennas, the matching of the impedance of transmission lines, the elements of transmission lines, aperture-type antennas for microwaves, and the functional characteristics of antennas for ultrashort waves.

  2. The 24 GHz measurements of 2.2 lambda conical horn antennas illuminating a conducting sheet

    NASA Technical Reports Server (NTRS)

    Cross, A. E.; Marshall, R. E.; Hearn, C. P.; Neece, R. T.

    1993-01-01

    Monostatic reflection-coefficient magnitude, absolute value of Gamma, measurements occurring between a radiating horn and a metal reflecting plate are presented for a family of three 2.2 lambda diameter conical horn antennas. The three horns have different aperture phase deviations: 6 deg, 22.5 deg, and 125 deg. Measurements of the magnitude of absolute value of Gamma as a function of horn-plate separation (d) extend from an effective antenna aperture short (d = O) to beyond the far-field boundary (d = 2D(sup 2)/lambda, where D is the antenna diameter). Measurement data are presented with various physical environments for each of the horns. Measured scalar data are compared with theoretical data from two models, a numerical model for a circular waveguide aperture in a ground plane and a scalar diffraction theory model. This work was conducted in support of the development effort for a spaceborne multifrequency microwave reflectometer designed to accurately determine the distance from a space vehicle's surface to a reflecting plasma boundary. The metal reflecting plate was used to simulate the RF reflectivity of a critically dense plasma. The resulting configuration, a ground plane mounted aperture facing a reflecting plane in close proximity, produces a strong interaction between the ground plane and the reflecting plate, especially at integral half-wavelength separations. The transition coefficient is characterized by large amplitude variations.

  3. 2-SR-based electrically small antenna for RFID applications

    NASA Astrophysics Data System (ADS)

    Paredes, Ferran; Zuffanelli, Simone; Aguilà, Pau; Zamora, Gerard; Martin, Ferran; Bonache, Jordi

    2016-04-01

    In this work, the 2-turn spiral resonator (2-SR) is proposed as an electrically small antenna for passive radio frequency identification (RFID) tags at the European ultra-high frequency (UHF) band. The radiation properties are studied in order to explore the viability of the 2-SR applied to tag antenna design. Based on analytical calculations, the radiation pattern is found to provide a cancelation of the radiation nulls. This results in a mitigation of the blind spots in the read range, which are present in typical UHF-RFID tags as an undesired feature. As a proof of concept, a passive tag of size 35 mm × 40 mm (λ 0/10 × λ 0/9) based on the 2-SR antenna is designed and fabricated. Good radiation efficiency (75 %) and a quasi-isotropic radiation pattern are obtained. The experimental tag read range for different directions is in good agreement with the simulation results. The measured read range exhibits maximum and minimum values of 6.7 and 3.5 m, respectively.

  4. Transformation from a Single Antenna to a Series Array Using Push/Pull Origami

    PubMed Central

    Shah, Syed Imran Hussain

    2017-01-01

    We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed origami antenna can be transformed to a series antenna array by pulling the frame. In order to push the antenna array back to a single antenna, the frame for each antenna element size must be different. The frame and supporting dielectric materials are built using a three-dimensional (3D) printer. The conductive patterns are inkjet-printed on paper. Thus, the proposed origami antenna is built using hybrid printing technology. The 10-dB impedance bandwidth is 2.5–2.65 GHz and 2.48–2.62 GHz for the single-antenna and array mode, respectively, and the peak gains in the single-antenna and array mode are 5.8 dBi and 7.6 dBi, respectively. The proposed antenna can be used for wireless remote-sensing applications. PMID:28846603

  5. Transformation from a Single Antenna to a Series Array Using Push/Pull Origami.

    PubMed

    Shah, Syed Imran Hussain; Lim, Sungjoon

    2017-08-26

    We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed origami antenna can be transformed to a series antenna array by pulling the frame. In order to push the antenna array back to a single antenna, the frame for each antenna element size must be different. The frame and supporting dielectric materials are built using a three-dimensional (3D) printer. The conductive patterns are inkjet-printed on paper. Thus, the proposed origami antenna is built using hybrid printing technology. The 10-dB impedance bandwidth is 2.5-2.65 GHz and 2.48-2.62 GHz for the single-antenna and array mode, respectively, and the peak gains in the single-antenna and array mode are 5.8 dBi and 7.6 dBi, respectively. The proposed antenna can be used for wireless remote-sensing applications.

  6. 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.

  7. A Modal Approach to Compact MIMO Antenna Design

    NASA Astrophysics Data System (ADS)

    Yang, Binbin

    MIMO (Multiple-Input Multiple-Output) technology offers new possibilities for wireless communication through transmission over multiple spatial channels, and enables linear increases in spectral efficiency as the number of the transmitting and receiving antennas increases. However, the physical implementation of such systems in compact devices encounters many physical constraints mainly from the design of multi-antennas. First, an antenna's bandwidth decreases dramatically as its electrical size reduces, a fact known as antenna Q limit; secondly, multiple antennas closely spaced tend to couple with each other, undermining MIMO performance. Though different MIMO antenna designs have been proposed in the literature, there is still a lack of a systematic design methodology and knowledge of performance limits. In this dissertation, we employ characteristic mode theory (CMT) as a powerful tool for MIMO antenna analysis and design. CMT allows us to examine each physical mode of the antenna aperture, and to access its many physical parameters without even exciting the antenna. For the first time, we propose efficient circuit models for MIMO antennas of arbitrary geometry using this modal decomposition technique. Those circuit models demonstrate the powerful physical insight of CMT for MIMO antenna modeling, and simplify MIMO antenna design problem to just the design of specific antenna structural modes and a modal feed network, making possible the separate design of antenna aperture and feeds. We therefore develop a feed-independent shape synthesis technique for optimization of broadband multi-mode apertures. Combining the shape synthesis and circuit modeling techniques for MIMO antennas, we propose a shape-first feed-next design methodology for MIMO antennas, and designed and fabricated two planar MIMO antennas, each occupying an aperture much smaller than the regular size of lambda/2 x lambda/2. Facilitated by the newly developed source formulation for antenna stored

  8. Beam ion acceleration by ICRH in JET discharges

    NASA Astrophysics Data System (ADS)

    Budny, R. V.; Gorelenkova, M.; Bertelli, N.; JET Collaboration

    2015-11-01

    The ion Monte-Carlo orbit integrator NUBEAM, used in TRANSP has been enhanced to include an ``RF-kick'' operator to simulate the interaction of RF fields and fast ions. The RF quasi-linear operator (localized in space) uses a second R-Z orbit integrator. We apply this to analysis of recent JET discharges using ICRH with the ITER-like first wall. An example of results for a high performance Hybrid discharge for which standard TRANSP analysis simulated the DD neutron emission rate below measurements, re-analysis using the RF-kick operator results in increased beam parallel and perpendicular energy densities (~=40% and 15% respectively), and increased beam-thermal neutron emission (~= 35%), making the total rate closer to the measurement. Checks of the numerics, comparisons with measurements, and ITER implications will be presented. Supported in part by the US DoE contract DE-AC02-09CH11466 and by EUROfusion No 633053.

  9. VIEW OF HELIX HOUSE NO. 2 (S87), WITH ANTENNA TOWER ...

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

    VIEW OF HELIX HOUSE NO. 2 (S-87), WITH ANTENNA TOWER CABLE SUPPORT IN FOREGROUND, LOOKING SOUTHEAST. - Naval Computer & Telecommunications Area Master Station, Eastern Pacific, Radio Transmitter Facility Lualualei, Helix House No. 2, Base of Radio Antenna Structure No. 427, Makaha, Honolulu County, HI

  10. OVERVIEW OF HELIX HOUSE NO. 2 (S87), WITH ANTENNA TOWERS, ...

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

    OVERVIEW OF HELIX HOUSE NO. 2 (S-87), WITH ANTENNA TOWERS, HELIX HOUSE NO. 1 (S-3) AND TRANSMITTER BLDG. (S-2) AT REAR, LOOKING WEST SOUTHWEST. - Naval Computer & Telecommunications Area Master Station, Eastern Pacific, Radio Transmitter Facility Lualualei, Helix House No. 2, Base of Radio Antenna Structure No. 427, Makaha, Honolulu County, HI

  11. New coplanar waveguide feed network for 2 x 2 linearly tapered slot antenna subarray

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Perl, Thomas D.; Lee, Richard Q.

    1992-01-01

    A novel feed method is presently demonstrated for a 2 x 2 linearly tapered slot antenna (LTSA) on the basis of a coplanar-waveguide (CPW)-to-slotline transition and a coax-to-CPW in-phase, four-way power divider. The LTSA subarray exhibits excellent radiation patterns and return-loss characteristics at 18 GHz, and has symmetric beamwidth; its compactness renders it applicable as either a feed for a reflector antenna or as a building-block for large arrays.

  12. Antenna Allocation in MIMO Radar with Widely Separated Antennas for Multi-Target Detection

    PubMed Central

    Gao, Hao; Wang, Jian; Jiang, Chunxiao; Zhang, Xudong

    2014-01-01

    In this paper, we explore a new resource called multi-target diversity to optimize the performance of multiple input multiple output (MIMO) radar with widely separated antennas for detecting multiple targets. In particular, we allocate antennas of the MIMO radar to probe different targets simultaneously in a flexible manner based on the performance metric of relative entropy. Two antenna allocation schemes are proposed. In the first scheme, each antenna is allocated to illuminate a proper target over the entire illumination time, so that the detection performance of each target is guaranteed. The problem is formulated as a minimum makespan scheduling problem in the combinatorial optimization framework. Antenna allocation is implemented through a branch-and-bound algorithm and an enhanced factor 2 algorithm. In the second scheme, called antenna-time allocation, each antenna is allocated to illuminate different targets with different illumination time. Both antenna allocation and time allocation are optimized based on illumination probabilities. Over a large range of transmitted power, target fluctuations and target numbers, both of the proposed antenna allocation schemes outperform the scheme without antenna allocation. Moreover, the antenna-time allocation scheme achieves a more robust detection performance than branch-and-bound algorithm and the enhanced factor 2 algorithm when the target number changes. PMID:25350505

  13. Antenna allocation in MIMO radar with widely separated antennas for multi-target detection.

    PubMed

    Gao, Hao; Wang, Jian; Jiang, Chunxiao; Zhang, Xudong

    2014-10-27

    In this paper, we explore a new resource called multi-target diversity to optimize the performance of multiple input multiple output (MIMO) radar with widely separated antennas for detecting multiple targets. In particular, we allocate antennas of the MIMO radar to probe different targets simultaneously in a flexible manner based on the performance metric of relative entropy. Two antenna allocation schemes are proposed. In the first scheme, each antenna is allocated to illuminate a proper target over the entire illumination time, so that the detection performance of each target is guaranteed. The problem is formulated as a minimum makespan scheduling problem in the combinatorial optimization framework. Antenna allocation is implemented through a branch-and-bound algorithm and an enhanced factor 2 algorithm. In the second scheme, called antenna-time allocation, each antenna is allocated to illuminate different targets with different illumination time. Both antenna allocation and time allocation are optimized based on illumination probabilities. Over a large range of transmitted power, target fluctuations and target numbers, both of the proposed antenna allocation schemes outperform the scheme without antenna allocation. Moreover, the antenna-time allocation scheme achieves a more robust detection performance than branch-and-bound algorithm and the enhanced factor 2 algorithm when the target number changes.

  14. A Frequency Reconfigurable MIMO Antenna System for Cognitive Radio Applications

    NASA Astrophysics Data System (ADS)

    Raza, A.; Khan, Muhammad U.; Tahir, Farooq A.

    2017-10-01

    In this paper, a two element frequency reconfigurable multiple-input-multiple-output (MIMO) antenna system is presented. The proposed antenna consists of miniaturized patch antenna elements, loaded with varactor diodes to achieve frequency reconfigurability. The antenna has bandwidth of 30 MHz and provides a smooth frequency sweep from 2.12 GHz to 2.4 GHz by varying the reverse bias voltage of varactor diode. The antenna is designed on an FR4 substrate and occupies a space of 50×100 × 0.8 mm3. The antenna is analyzed for its far-field characteristics as well as for MIMO performance parameters. Designed antenna showed good performance and is suitable for cognitive radios (CR) applications.

  15. A New Metasurface Superstrate Structure for Antenna Performance Enhancement.

    PubMed

    Islam, Mohammad Tariqul; Ullah, Mohammad Habib; Singh, Mandeep Jit; Faruque, Mohammad Rashed Iqbal

    2013-07-31

    A new metasurface superstrate structure (MSS)-loaded dual band microstrip line-fed small patch antenna is presented in this paper. The proposed antenna was designed on a ceramic-filled bioplastic sandwich substrate with a high dielectric constant. The proposed 7 × 6 element, square-shaped, single-sided MSS significantly improved the bandwidth and gain of the proposed antenna. The proposed MSS incorporated a slotted patch antenna that effectively increased the measured operating bandwidth from 13.3% to 18.8% and from 14.8% to 23.2% in the lower and upper bands, respectively. Moreover, the average gain of the proposed MSS-based antenna was enhanced from 2.12 dBi to 3.02 dBi in the lower band and from 4.10 dBi to 5.28 dBi in the upper band compared to the patch antenna alone. In addition to the bandwidth and gain improvements, more directive radiation characteristics were also observed from the MSS antenna compared to the patch itself. The effects of the MSS elements and the ground plane length on the reflection coefficient of the antenna were analyzed and optimized. The overall performance makes the proposed antenna appropriate for RFID and WLAN applications.

  16. Highly Omnidirectional and Frequency Controllable Carbon/Polyaniline-based 2D and 3D Monopole Antenna

    NASA Astrophysics Data System (ADS)

    Shin, Keun-Young; Kim, Minkyu; Lee, James S.; Jang, Jyongsik

    2015-09-01

    Highly omnidirectional and frequency controllable carbon/polyaniline (C/PANI)-based, two- (2D) and three-dimensional (3D) monopole antennas were fabricated using screen-printing and a one-step, dimensionally confined hydrothermal strategy, respectively. Solvated C/PANI was synthesized by low-temperature interfacial polymerization, during which strong π-π interactions between graphene and the quinoid rings of PANI resulted in an expanded PANI conformation with enhanced crystallinity and improved mechanical and electrical properties. Compared to antennas composed of pristine carbon or PANI-based 2D monopole structures, 2D monopole antennas composed of this enhanced hybrid material were highly efficient and amenable to high-frequency, omnidirectional electromagnetic waves. The mean frequency of C/PANI fiber-based 3D monopole antennas could be controlled by simply cutting and stretching the antenna. These antennas attained high peak gain (3.60 dBi), high directivity (3.91 dBi) and radiation efficiency (92.12%) relative to 2D monopole antenna. These improvements were attributed the high packing density and aspect ratios of C/PANI fibers and the removal of the flexible substrate. This approach offers a valuable and promising tool for producing highly omnidirectional and frequency-controllable, carbon-based monopole antennas for use in wireless networking communications on industrial, scientific, and medical (ISM) bands.

  17. Highly Omnidirectional and Frequency Controllable Carbon/Polyaniline-based 2D and 3D Monopole Antenna

    PubMed Central

    Shin, Keun-Young; Kim, Minkyu; Lee, James S.; Jang, Jyongsik

    2015-01-01

    Highly omnidirectional and frequency controllable carbon/polyaniline (C/PANI)-based, two- (2D) and three-dimensional (3D) monopole antennas were fabricated using screen-printing and a one-step, dimensionally confined hydrothermal strategy, respectively. Solvated C/PANI was synthesized by low-temperature interfacial polymerization, during which strong π–π interactions between graphene and the quinoid rings of PANI resulted in an expanded PANI conformation with enhanced crystallinity and improved mechanical and electrical properties. Compared to antennas composed of pristine carbon or PANI-based 2D monopole structures, 2D monopole antennas composed of this enhanced hybrid material were highly efficient and amenable to high-frequency, omnidirectional electromagnetic waves. The mean frequency of C/PANI fiber-based 3D monopole antennas could be controlled by simply cutting and stretching the antenna. These antennas attained high peak gain (3.60 dBi), high directivity (3.91 dBi) and radiation efficiency (92.12%) relative to 2D monopole antenna. These improvements were attributed the high packing density and aspect ratios of C/PANI fibers and the removal of the flexible substrate. This approach offers a valuable and promising tool for producing highly omnidirectional and frequency-controllable, carbon-based monopole antennas for use in wireless networking communications on industrial, scientific, and medical (ISM) bands. PMID:26338090

  18. 2. View of southerly DR 1 antenna looking north 25 ...

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

    2. View of southerly DR 1 antenna looking north 25 degrees west and and showing radar scanner building no. 105 east face through antenna. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  19. 3. View of middle DR 2 antenna looking north 30 ...

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

    3. View of middle DR 2 antenna looking north 30 degrees west and showing radar scanner building no. 105 east face through antenna. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  20. Broadband standard dipole antenna for antenna calibration

    NASA Astrophysics Data System (ADS)

    Koike, Kunimasa; Sugiura, Akira; Morikawa, Takao

    1995-06-01

    Antenna calibration of EMI antennas is mostly performed by the standard antenna method at an open-field test site using a specially designed dipole antenna as a reference. In order to develop broadband standard antennas, the antenna factors of shortened dipples are theoretically investigated. First, the effects of the dipole length are analyzed using the induced emf method. Then, baluns and loads are examined to determine their influence on the antenna factors. It is found that transformer-type baluns are very effective for improving the height dependence of the antenna factors. Resistive loads are also useful for flattening the frequency dependence. Based on these studies, a specification is developed for a broadband standard antenna operating in the 30 to 150 MHz frequency range.

  1. A Wideband Circularly Polarized Pixelated Dielectric Resonator Antenna.

    PubMed

    Trinh-Van, Son; Yang, Youngoo; Lee, Kang-Yoon; Hwang, Keum Cheol

    2016-08-23

    The design of a wideband circularly polarized pixelated dielectric resonator antenna using a real-coded genetic algorithm (GA) is presented for far-field wireless power transfer applications. The antenna consists of a dielectric resonator (DR) which is discretized into 8 × 8 grid DR bars. The real-coded GA is utilized to estimate the optimal heights of the 64 DR bars to realize circular polarization. The proposed antenna is excited by a narrow rectangular slot etched on the ground plane. A prototype of the proposed antenna is fabricated and tested. The measured -10 dB reflection and 3 dB axial ratio bandwidths are 32.32% (2.62-3.63 GHz) and 14.63% (2.85-3.30 GHz), respectively. A measured peak gain of 6.13 dBic is achieved at 3.2 GHz.

  2. A New Metasurface Superstrate Structure for Antenna Performance Enhancement

    PubMed Central

    Islam, Mohammad Tariqul; Ullah, Mohammad Habib; Singh, Mandeep Jit; Faruque, Mohammad Rashed Iqbal

    2013-01-01

    A new metasurface superstrate structure (MSS)-loaded dual band microstrip line-fed small patch antenna is presented in this paper. The proposed antenna was designed on a ceramic-filled bioplastic sandwich substrate with a high dielectric constant. The proposed 7 × 6 element, square-shaped, single-sided MSS significantly improved the bandwidth and gain of the proposed antenna. The proposed MSS incorporated a slotted patch antenna that effectively increased the measured operating bandwidth from 13.3% to 18.8% and from 14.8% to 23.2% in the lower and upper bands, respectively. Moreover, the average gain of the proposed MSS-based antenna was enhanced from 2.12 dBi to 3.02 dBi in the lower band and from 4.10 dBi to 5.28 dBi in the upper band compared to the patch antenna alone. In addition to the bandwidth and gain improvements, more directive radiation characteristics were also observed from the MSS antenna compared to the patch itself. The effects of the MSS elements and the ground plane length on the reflection coefficient of the antenna were analyzed and optimized. The overall performance makes the proposed antenna appropriate for RFID and WLAN applications. PMID:28811432

  3. Analysis of SIR-A antenna tests

    NASA Technical Reports Server (NTRS)

    Carver, K. R.; Post, C. C.

    1979-01-01

    The purpose of this report is: (1) to provide an analysis of antenna test procedures used at JPL for measurement of the SIR-A antenna and (2) to point out that the measured E-plane patterns differ in some significant respects from the true pattern as experienced during the OFT-2 space deployment; this results principally from the finite range length associated with the JPL far-field range.

  4. Dual Mode Slotted Monopole Antenna

    DTIC Science & Technology

    2017-01-05

    of 15 DUAL MODE SLOTTED MONOPOLE ANTENNA STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and used by...to a dual mode antenna having one mode as a slotted cylinder antenna and another mode as a monopole antenna . (2) Description of the Prior Art...0004] Slotted cylinder antennas are popular antennas for use in line of sight communications systems, especially where the carrier frequency exceeds

  5. Fluorescence polarization measures energy funneling in single light-harvesting antennas--LH2 vs conjugated polymers.

    PubMed

    Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J; Sforazzini, Giuseppe; Anderson, Harry L; Pullerits, Tõnu; Scheblykin, Ivan G

    2015-10-19

    Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.

  6. Optical antenna gain. I - Transmitting antennas

    NASA Technical Reports Server (NTRS)

    Klein, B. J.; Degnan, J. J.

    1974-01-01

    The gain of centrally obscured optical transmitting antennas is analyzed in detail. The calculations, resulting in near- and far-field antenna gain patterns, assume a circular antenna illuminated by a laser operating in the TEM-00 mode. A simple polynomial equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn that display the losses in antenna gain due to pointing errors and the cone angle of the beam in the far field as a function of antenna aperture size and its central obscuration. The results are presented in a series of graphs that allow the rapid and accurate evaluation of the antenna gain which may then be substituted into the conventional range equation.

  7. Antenna testing for the Inmarsat 2 ground control system

    NASA Astrophysics Data System (ADS)

    Ashton, C.

    1992-02-01

    This article describes how the antennas of the Inmarsat 2 TT&C and IOT ground stations were tested and calibrated. It explains the main test methods used, giving the theory behind the tests and indicates some of the practical difficulties encountered during testing. Techniques described include the use of radio stars, boresight antennas and satellite verification testing using Intelsat and Inmarsat satellites. Parameters tested include gain, G/T (figure of merit), sidelobe patterns, cross polar discrimination and isolation.

  8. The fractionated dipole antenna: A new antenna for body imaging at 7 Tesla.

    PubMed

    Raaijmakers, Alexander J E; Italiaander, Michel; Voogt, Ingmar J; Luijten, Peter R; Hoogduin, Johannes M; Klomp, Dennis W J; van den Berg, Cornelis A T

    2016-03-01

    Dipole antennas in ultrahigh field MRI have demonstrated advantages over more conventional designs. In this study, the fractionated dipole antenna is presented: a dipole where the legs are split into segments that are interconnected by capacitors or inductors. A parameter study has been performed on dipole antenna length using numerical simulations. A subsequent simulation study investigates the optimal intersegment capacitor/inductor value. The resulting optimal design has been constructed and compared to a previous design, the single-side adapted dipole (SSAD) by simulations and measurements. An array of eight elements has been constructed for prostate imaging on four subjects (body mass index 20-27.5) using 8 × 2 kW amplifiers. For prostate imaging at 7T, lowest peak local specific-absorption rate (SAR) levels are achieved if the antenna is 30 cm or longer. A fractionated dipole antenna design with inductors between segments has been chosen to achieve even lower SAR levels and more homogeneous receive sensitivities. With the new design, good quality prostate images are acquired. SAR levels are reduced by 41% to 63% in comparison to the SSAD. Coupling levels are moderate (average nearest neighbor: -14.6 dB) for each subject and prostate B1+ levels range from 12 to 18 μT. © 2015 Wiley Periodicals, Inc.

  9. A 1 GHz Oscillator-Type Active Antenna

    NASA Technical Reports Server (NTRS)

    Jordan, Jennifer L.; Scardelletti, Maximilian; Ponchak, George E.

    2008-01-01

    Wireless sensors are desired for monitoring aircraft engines, automotive engines, industrial machinery, and many other applications. The most important requirement of sensors is that they do not interfere with the environment that they are monitoring. Therefore, wireless sensors must be small, which demands a high level of integration. Sensors that modulate an oscillator active antenna have advantages of small size, high level of integration, and lower packaging cost. Several types of oscillator active antennas have been reported. Ip et al. demonstrated a CPW line fed patch antenna with a feedback loop [1]. No degradation in performance was noticed without a ground plane. A GaAs FET was used in an amplifier/oscillator-based active antenna [2]. An oscillator based on a Cree SiC transistor was designed and characterized in [3]. This paper reports the integration of the SiC Clapp oscillator to a slotline loop antenna.

  10. Reconfigurable antenna options for 2.45/5 GHz wireless body area networks in healthcare applications.

    PubMed

    Abbas, Syed Muzahir; Ranga, Yogesh; Esselle, Karu P

    2015-01-01

    This paper presents electronically reconfigurable antenna options in healthcare applications. They are suitable for wireless body area network devices operating in the industrial, scientific, and medical (ISM) band at 2.45 GHz and IEEE 802.11 Wireless Local Area Network (WLAN) band at 5 GHz (5.15-5.35 GHz, 5.25-5.35 GHz). Two types of antennas are investigated: Antenna-I has a full ground plane and Antenna-II has a partial ground plane. The proposed antennas provide ISM operation in one mode while in another mode they support 5 GHz WLAN band. Their performance is assessed for body centric wireless communication using a simplified human body model. Antenna sensitivity to the gap between the antenna and the human body is investigated for both modes of each antenna. The proposed antennas exhibit a wide radiation pattern along the body surface to provide wide coverage and their small width (14 mm) makes them suitable for on-body communication in healthcare applications.

  11. Design of a C- Band Circular Polarization Microstrip Antenna

    NASA Astrophysics Data System (ADS)

    Yohandri; Jumiah, Yusna; Tetuko Sri Sumantyo, Josaphat

    2018-04-01

    The development of circularly polarized microstrip antenna is an interesting topic in current research, due to its superiority in various applications. In this work, the design of a circular polarization antenna that will be operated in the C-band range will be described. The developed antenna is intended to be used for Synthetic Aperture Radar (SAR) applications. Through this application, various targets or areas on the surface of the earth, such as buildings, soil and land can be observed. To get the ideal antenna characteristic, in this research the various parameters in antenna design will be simulated. A software CST Studio will be operated in this simulation. Based on the simulation results, the optimum parameters are obtained in term of reflection coefficient, VSWR, axial ratio, and gain. The reflection coefficient of the antenna (S11) is obtained at -19.75 dB and VSWR of 1.23. Meanwhile, the axial ratio and gain of the antenna were obtained at 2.66 dB and 2.1 dBi, respectively. Based on this simulated results, antenna design is potential to be developed and fabricated for SAR sensor applications.

  12. 5. View of middle DR 2 antenna with DR 1 ...

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

    5. View of middle DR 2 antenna with DR 1 antenna in background. Photograph shows on left side at bottom foundation berm and along right side bottom stanchion concrete foundations at bottom structural steel assembly. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  13. Bandwidth enhancement of a microstrip patch antenna for ultra-wideband applications

    NASA Astrophysics Data System (ADS)

    Anum, Khanda; Singh, Milind Saurabh; Mishra, Rajan; Tripathi, G. S.

    2018-04-01

    The microstrip antennas are used where size, weight, cost, and performance are constraints. Microstrip antennas (MSA) are being used in many government and commercial applications among which it is mostly used in wireless communication. The proposed antenna is designed for Ultra-wideband (UWB), it is designed on FR4 substrate material with ɛr = 4.3 and 0.0025 loss tangent. The shape and size of patch in microstrip patch antenna plays an important role in its performance. In the proposed antenna design the respective changes have been introduced which includes slotting the feedline,adding a curved slot in patch and change in patch shape itself to improve the bandwidth of the conventional antenna. The simulated results of proposed antenna shows impedance bandwidth (defined by 10 dB return loss) of 2-11.1GHz, VSWR<2 for entire bandwidth of antenna and peak gain is 5.2 dB. Thus the antenna covers the UWB range and it can also be used for bands such as 2.4/3.6/5 -GHz WLAN bands, 2.5/3.5/5.5GHz WiMAX bands and X band satellite communication at 7.25-8.395 GHz.

  14. Miniaturized printed K shaped monopole antenna with truncated ground plane for 2.4/5.2/5.5/5.8 wireless lan applications

    NASA Astrophysics Data System (ADS)

    Chandan, Bharti, Gagandeep; Srivastava, Toolika; Rai, B. S.

    2018-04-01

    A novel truncated ground plane monopole antenna is proposed for wide band wireless local area network (WLAN) applications. The antenna contains a rectangular patch with a rectangular ring, a circular slot and a truncated ground plane printed on opposite sides of a low cost substrate FR4. The operating frequency bands for the antenna are band1 (2.4-2.88 GHz) and band 2 (4.8-6.3 GHz) with ≤ - 10 dB return loss which covers 2.4/5.2/5.5/5.8 GHz WLAN bands. The antenna is compact with overall dimension 26×40×0.8 mmł and with the dimension of patch 16×16×0.8 mm3. The two bands of antenna is obtained by cutting a rectangular ring and a circular slot in the patch and return loss is improved by cutting two rectangular slot in the ground plane. Performance measures of the antenna are shown in terms of return loss, current distribution, radiation pattern and gain. To verify the simulated results, the antenna is also fabricated and tested. The simulated and fabricated results have been found in good agreement.

  15. Dual band monopole antenna for WLAN 2.4/5.2/5.8 with truncated ground

    NASA Astrophysics Data System (ADS)

    Chandan, Bharti, Gagandeep; Srivastava, Toolika; Rai, B. S.

    2018-04-01

    A dual-band mono-pole antenna is proposed for Wireless LAN applications. The WLAN band is obtained by cutting a rectangular ring and a circular slot in the radiating patch. The overall dimension of antenna is 17×16.5×0.8 mmł. The frequency bands obtained are 2.38-2.9 GHz and 4.7-6.1 GHz with ≤ - 10 dB return loss which covers WLAN 2.4/5.2/5.8 GHz bands. The behavior of the antenna is analyzed in terms of radiation pattern, peak realized gain, radiation efficiency and surface current density. It has dipole like radiation pattern with gain of 2.33 - 4.31 dBi for lower frequency band and 4.29 - 5.16 dBi for upper frequency band with radiation efficiency of 95-98% and 93-96% respectively. The parametric analysis is carried out to understand the consequence of the various shape parameters and to get an optimum design. The simulation and measurement gave the results having close agreement.

  16. Radio antennas

    NASA Astrophysics Data System (ADS)

    Gibson, S. W.

    This book is concerned with providing an explanation of the function of an antenna without delving too deeply into the mathematics or theory. The characteristics of an antenna are examined, taking into account aspects of antenna radiation, wave motion on the antenna, resistance in the antenna, impedance, the resonant antenna, the effect of the ground, polarization, radiation patterns, coupling effects between antenna elements, and receiving vs. transmitting. Aspects of propagation are considered along with the types of antennas, transmission lines, matching devices, questions of antenna design, antennas for the lower frequency bands, antennas for more than one band, limited space antennas, VHF antennas, and antennas for 20, 15, and 10 meters. Attention is given to devices for measuring antenna parameters, approaches for evaluating the antenna, questions of safety, and legal aspects.

  17. Antenna coupling--a novel mechanism of radiofrequency electrosurgery complication: practical implications.

    PubMed

    Robinson, Thomas N; Barnes, Kelli S; Govekar, Henry R; Stiegmann, Greg V; Dunn, Christina L; McGreevy, Francis T

    2012-08-01

    (1) To determine if antenna coupling occurs in common operating room scenarios. (2) To define modifiable clinical variables that reduce the magnitude of antenna coupling. Mechanisms of electrosurgical burns where monitoring devices contact the surgical patient are unclear. Antenna coupling occurs when the "bovie" active electrode (electrically active transmitting antenna) emits energy, which is captured by a nonelectrically active wire (electrically inactive receiving antenna) in close proximity without direct contact. Monopolar radiofrequency energy was delivered to a laparoscopic instrument (electrically active transmitting antenna), whereas other nonelectrically active wires (electrically inactive receiving antenna) including electrocardiogram (EKG) lead, nonactive "bovie" pencil, and nerve electrode monitor were placed in proximity. Temperature changes of tissue placed adjacent to the electrically inactive receiving antennae were measured. Nonelectrically active wires (receiving antenna) increase tissue temperature when lying parallel to the active electrode cord: EKG pad 2.4°C ± 1.2°C (P = 0.002), "bovie" pencil tip 90°C ± 9°C (P < 0.001), and nerve electrode monitor 106°C ± 12°C (P < 0.001). Factors that reduced the heat generated by antenna coupling included the following: increasing angulation between transmitting and receiving antennae (parallel = 90°C ± 9°C; 45° angle = 53°C ± 10°C; perpendicular = 35°C ± 11°C; P < .001), increasing separation distance between parallel transmitting and receiving antenna (<1 cm = 90°C ± 9°C; 15 cm = 44°C ± 18°C; 30 cm = 39°C ± 2°C; P < .001); and decreasing generator power setting (15 W = 59°C ± 11°C; 30 W = 90°C ± 9°C; 45 W = 98°C ± 8°C; P < .001). Antenna coupling occurs in common operating room scenarios. Simple, practical measures by the surgeon, such as orienting the receiving antenna at a greater angle and with greater separation to the active electrode cord, or lowering the

  18. A microfabricated low-profile wideband antenna array for terahertz communications.

    PubMed

    Luk, K M; Zhou, S F; Li, Y J; Wu, F; Ng, K B; Chan, C H; Pang, S W

    2017-04-28

    While terahertz communications are considered to be the future solutions for the increasing demands on bandwidth, terahertz equivalents of radio frequency front-end components have not been realized. It remains challenging to achieve wideband, low profile antenna arrays with highly directive beams of radiation. Here, based on the complementary antenna approach, a wideband 2 × 2 cavity-backed slot antenna array with a corrugated surface is proposed. The approach is based on a unidirectional antenna with a cardiac radiation pattern and stable frequency characteristics that is achieved by integrating a series-resonant electric dipole with a parallel-resonant magnetic dipole. In this design, the slots work as magnetic dipoles while the corrugated surface radiates as an array of electric dipoles. The proposed antenna is realized at 1 THz operating frequency by stacking multiple metallized layers using the microfabrication technology. S-parameter measurements of this terahertz low-profile metallic antenna array demonstrate high efficiency at terahertz frequencies. Fractional bandwidth and gain are measured to be 26% and 14 dBi which are consistent with the simulated results. The proposed antenna can be used as the building block for larger antenna arrays with more directive beams, paving the way to develop high gain low-profile antennas for future communication needs.

  19. A Compact, Broadband Antenna for Planetary Surface-to-Surface Wireless Communications

    NASA Technical Reports Server (NTRS)

    Barr, Philip; Zaman, Afroz; Miranda, Felix

    2006-01-01

    The Compact Microstrip Monopole Antenna (CMMA) is a novel antenna design that combines a microstrip patch antenna with a three-dimensional structure to attain a highly directive, broadband, compact antenna. A Tri-Lobed Patch (TLP) was designed to minimize the patch's area while reducing the antenna's operating frequency. A Grounding Wall (GW) connects the patch to the ground plane and a Vertical Enclosure Wall (VEW) extends up away from portions of the patch's perimeter. This VEW supplies the antenna with a higher directivity in the radial direction as well as reduces the operating frequency. The CMMA was designed to operate at 2.23 GHz, but experimental results have shown this antenna resonates at 2.05 GHz which is on the order of approximately Lambda(sub o)/11.6 with respect to the antenna's largest dimension, with a directivity and bandwidth of 6.0 dBi, and 130 MHz (6.3 percent), respectively. This miniature, radially emitting antenna makes the CMMA attractive for planetary-based surface-to-surface communications.

  20. A Mars Riometer: Antenna Considerations

    NASA Technical Reports Server (NTRS)

    Fry, Craig D.

    2001-01-01

    This is the final report on NASA Grant NAG5-9706. This project explored riometer (relative ionospheric opacity meter) antenna designs that would be practical for a Mars surface or balloon mission. The riometer is an important radio science instrument for terrestrial aeronomy investigations. The riometer measures absorption of cosmic radio waves by the overhead ionosphere. Studies have shown the instrument should work well on Mars, which has an appreciable daytime ionosphere. There has been concern that the required radio receiver antenna (with possibly a 10 meter scale size) would be too large or too difficult to deploy on Mars. This study addresses those concerns and presents several antenna designs and deployment options. It is found that a Mars balloon would provide an excellent platform for the riometer antenna. The antenna can be incorporated into the envelope design, allowing self-deployment of the antenna as the balloon inflates.

  1. Unfurlable satellite antennas - A review

    NASA Technical Reports Server (NTRS)

    Roederer, Antoine G.; Rahmat-Samii, Yahia

    1989-01-01

    A review of unfurlable satellite antennas is presented. Typical application requirements for future space missions are first outlined. Then, U.S. and European mesh and inflatable antenna concepts are described. Precision deployables using rigid panels or petals are not included in the survey. RF modeling and performance analysis of gored or faceted mesh reflector antennas are then reviewed. Finally, both on-ground and in-orbit RF test techniques for large unfurlable antennas are discussed.

  2. One- and two-dimensional antenna arrays for microwave wireless power transfer (MWPT) systems and dual-antenna transceivers

    NASA Astrophysics Data System (ADS)

    Lin, Yo-Sheng; Hu, Chun-Hao; Chang, Chi-Ho; Tsao, Ping-Chang

    2018-06-01

    In this work, we demonstrate novel one-dimensional (1D) and two-dimensional (2D) antenna arrays for both microwave wireless power transfer (MWPT) systems and dual-antenna transceivers. The antenna array can be used as the MWPT receiving antenna of an integrated MWPT and Bluetooth (BLE) communication module (MWPT-BLE module) for smart CNC (computer numerical control) spindle incorporated with the cloud computing system SkyMars. The 2D antenna array has n rows of 1 × m 1D array, and each array is composed of multiple (m) differential feeding antenna elements. Each differential feeding antenna element is a differential feeding structure with a microstrip antenna stripe. The stripe length is shorter than one wavelength to minimise the antenna area and to prevent being excited to a high-order mode. That is, the differential feeding antenna element can suppress the even mode. The mutual coupling between the antenna elements can be suppressed, and the isolation between the receiver and the transmitter can be enhanced. An inclination angle of the main beam aligns with the broadside, and the main beam is further concentrated and shrunk at the elevation direction. Moreover, if more differential feeding antenna elements are used, antenna gain and isolation can be further enhanced. The excellent performance of the proposed antenna arrays indicates that they are suitable for both MWPT systems and dual-antenna transceivers.

  3. 89. View of DR 2 antenna (structure no. 736) at ...

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

    89. View of DR 2 antenna (structure no. 736) at 65 percent completion showing erection process. Antenna system designed and factory construction by D.S. Kennedy & Company., Comasset, MA, 1958. Note scanner radar building in background. Official photograph BMEWS Project by unknown photographer, 11 July, 1960, Photographic Services, Riverton, NJ, BMEWS, clear as negative no. A-824. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  4. 3-D printed 2.4 GHz rectifying antenna for wireless power transfer applications

    NASA Astrophysics Data System (ADS)

    Skinner, Matthew

    In this work, a 3D printed rectifying antenna that operates at the 2.4GHz WiFi band was designed and manufactured. The printed material did not have the same properties of bulk material, so the printed materials needed to be characterized. The antenna and rectifying circuit was printed out of Acrylonitrile Butadiene Styrene (ABS) filament and a conductive silver paste, with electrical components integrated into the circuit. Before printing the full rectifying antenna, each component was printed and evaluated. The printed antenna operated at the desired frequency with a return loss of -16 dBm with a bandwidth of 70MHz. The radiation pattern was measured in an anechoic chamber with good matching to the model. The rectifying circuit was designed in Ansys Circuit Simulation using Schottky diodes to enable the circuit to operate at lower input power levels. Two rectifying circuits were manufactured, one by printing the conductive traces with silver ink, and one with traces made from copper. The printed silver ink is less conductive than the bulk copper and therefore the output voltage of the printed rectifier was lower than the copper circuit. The copper circuit had an efficiency of 60% at 0dBm and the printed silver circuit had an efficiency of 28.6% at 0dBm. The antenna and rectifying circuits were then connected to each other and the performance was compared to a fully printed integrated rectifying antenna. The rectifying antennas were placed in front of a horn antenna while changing the power levels at the antenna. The efficiency of the whole system was lower than the individual components but an efficiency of 11% at 10dBm was measured.

  5. High temperature antenna development for space shuttle, volume 2. [space environment simulation effects on antenna radiation patterns

    NASA Technical Reports Server (NTRS)

    Kuhlman, E. A.

    1974-01-01

    An S-band antenna system and a group of off-the-shelf aircraft antenna were exposed to temperatures simulating shuttle orbital cold soak and entry heating. Radiation pattern and impedance measurements before and after exposure to the thermal environments were used to evaluate the electrical performance. The results of the electrical and thermal testing are given. Test data showed minor changes in electrical performance and established the capability of these antenna to withstand both the low temperatures of space flight and the high temperatures of entry.

  6. Largely enhanced photocatalytic activity of Au/XS2/Au (X = Re, Mo) antenna-reactor hybrids: charge and energy transfer.

    PubMed

    Chen, Kai; Ding, Si-Jing; Luo, Zhi-Jun; Pan, Gui-Ming; Wang, Jia-Hong; Liu, Jia; Zhou, Li; Wang, Qu-Quan

    2018-02-22

    An antenna-reactor hybrid coupling plasmonic antenna with catalytic nanoparticles is a new strategy to optimize photocatalytic activity. Herein, we have rationally proposed a Au/XS 2 /Au (X = Re, Mo) antenna reactor, which has a large Au core as the antenna and small satellite Au nanoparticles as the reactor separated by an ultrathin two-dimensional transition-metal dichalcogenide XS 2 shell (∼2.6 nm). Due to efficient charge transfer across the XS 2 shell as well as energy transfer via coupling of the Au antenna and Au reactor, the photocatalytic activity has been largely enhanced: Au/ReS 2 /Au exhibits a 3.59-fold enhancement, whereas Au/MoS 2 /Au exhibits a 2.66-fold enhancement as compared to that of the sum of the three individual components. The different enhancement in the Au/ReS 2 /Au and Au/MoS 2 /Au antenna-reactor hybrid is related to the competition and cooperation of charge and energy transfer. These results indicate the great potential of the Au/XS 2 /Au antenna-reactor hybrid for the development of highly efficient plasmonic photocatalysts.

  7. Broadband Cylindrical Antenna and Method

    DTIC Science & Technology

    2016-07-27

    1 of 12 BROADBAND CYLINDRICAL ANTENNA AND METHOD STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...directed to a cylindrical antenna having a broader bandwidth and a method for making such an antenna . (2) Description of the Prior Art [0004...Slotted cylinder antennas have been proposed in submarine applications before. For example, in U.S. Patent No. 6,127,983, Rivera and Josypenko disclose

  8. Phased Array GNSS Antenna for the FORMOSAT-7/COSMIC-2 Radio Occultation Mission

    NASA Technical Reports Server (NTRS)

    Turbiner, Dmitry; Young, Larry E.; Meehan, Tom K.

    2012-01-01

    Future GNSS remote sensing instruments such as the TriG receiver require more capable antennas than those flown on missions such as COSMIC. To maximize the number of ionospheric and atmospheric profiles, the TriG receiver will be capable of tracking legacy and new GPS signals such as L5, L2C and L1C; GLONASS CDMA and Galileo E1 and E5a. There has been an in-house effort at JPL to develop a set of antennas that would provide excellent Radio Occultations performance as well as navigation and ionospheric profiling. This effort is on-going but near completion for the manufacture and delivery of a set of flight antennas for the FORMOSAT-7/COSMIC-2 mission.

  9. 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.

  10. Improved Gain Microstrip Patch Antenna

    DTIC Science & Technology

    2015-08-06

    08-2015 Publication Improved Gain Microstrip Patch Antenna David A. Tonn Naval Under Warfare Center Division, Newport 1176 Howell St., Code 00L...GAIN MICROSTRIP PATCH ANTENNA STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and used by or for the...patch antenna having increased gain, and an apparatus for increasing the gain and bandwidth of an existing microstrip patch antenna . (2) Description

  11. A broadband double-slot waveguide antenna

    NASA Astrophysics Data System (ADS)

    Kisliuk, M.; Axelrod, A.

    1987-09-01

    A double transverse slot broadband antenna based on the H-guide transverse-slot radiator design of Kisliuk and Axelrod (1985) is described. The double transverse slot antenna may be used in microwave and mm-wave applications (as a phased array element), in imaging systems, or as a stand-alone linearly polarized antenna. The equations for calculating the radiation efficiency and the input impedance and the experimental and theoretical curves for radiation efficiency of the double-slot antenna are presented along with diagrams of the antenna and the equivalent circuit of an individual slot in a slot array.

  12. Assessment of a field-aligned ICRF antenna

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wukitch, S. J.; Brunner, D.; Ennever, P.

    Impurity contamination and localized heat loads associated with ion cyclotron range of frequency (ICRF) antenna operation are among the most challenging issues for ICRF utilization.. Another challenge is maintaining maximum coupled power through plasma variations including edge localized modes (ELMs) and confinement transitions. Here, we report on an experimental assessment of a field aligned (FA) antenna with respect to impurity contamination, impurity sources, RF enhanced heat flux and load tolerance. In addition, we compare the modification of the scrape of layer (SOL) plasma potential of the FA antenna to a conventional, toroidally aligned (TA) antenna, in order to explore themore » underlying physics governing impurity contamination linked to ICRF heating. The FA antenna is a 4-strap ICRF antenna where the current straps and antenna enclosure sides are perpendicular to and the Faraday screen rods are parallel to the total magnetic field. In principle, alignment with respect to the total magnetic field minimizes integrated E∥ (electric field along a magnetic field line) via symmetry. Consistent with expectations, we observed that the impurity contamination and impurity source at the FA antenna are reduced compared to the TA antenna. In both L and H-mode discharges, the radiated power is 20–30% lower for a FA-antenna heated discharge than a discharge heated with the TA-antennas. Further we observe that the fraction of RF energy deposited upon the antenna is less than 0.4 % of the total injected RF energy in dipole phasing. The total deposited energy increases significantly when the FA antenna is operated in monopole phasing. The FA antenna also exhibits an unexpected load tolerance for ELMs and confinement transitions compared to the TA antennas. However, inconsistent with expectations, we observe RF induced plasma potentials to be nearly identical for FA and TA antennas when operated in dipole phasing. In monopole phasing, the FA antenna has the highest

  13. Wide sector coverage antennas

    NASA Astrophysics Data System (ADS)

    Yaw, D. F.

    1984-09-01

    The general design and performance characteristics of transmit and receive antennas that are currently used in electronic warfare systems are reviewed. Among transmit antennas, three-to-one bandwidth, asymmetric-beam, and circularly polarized horns are discussed, as are extremely broadband monopoles and spiral antennas. In a discussion of receive antennas, attention is given to flat and conical spirals, including cavity-backed flat spirals operating over the 2.5-18 GHz range; log periodic dipoles; and biconical horns. Finally, the design configurations and performance of interferometer direction-finding systems are briefly discussed.

  14. Structural Test and Analysis of a Hybrid Inflatable Antenna

    NASA Technical Reports Server (NTRS)

    Gaspar, James L.; Mann, Troy; Sreekantamurthy, Tham; Behun, Vaughn

    2007-01-01

    NASA is developing ultra-lightweight structures technology for communication antennas for space missions. One of the research goals is to evaluate the structural characteristics of inflatable and rigidizable antennas through test and analysis. Being able to test and analyze the structural characteristics of a full scale antenna is important to enable the simulation of various mission scenarios to determine system performance in space. Recent work completed to evaluate a Hybrid Inflatable Antenna concept will be discussed. Tests were completed on a 2-m prototype to optimize its static shape and identify its modal dynamics that are important for analytical model validation. These test results were used to evaluate a preliminary finite element model of the antenna, and this model development and correlation activity is also described in the paper.

  15. Multilayer Patch Antenna Surrounded by a Metallic Wall

    NASA Technical Reports Server (NTRS)

    Zawadzki, Mark; Huang, John

    2003-01-01

    A multilayer patch antenna, similar to a Yagi antenna, surrounded by a metallic wall has been devised to satisfy requirements to fit within a specified size and shape and to generate a beam with a half-power angular width of <=40 deg. This antenna provides a gain of about 14 dB; in contrast, the gain of a typical single-patch antenna lies between 5 and 6 dB. This antenna can be considered an alternative to a two-dimensional array of patch antenna elements, or to a horn or helical antenna. Unlike a two-dimensional array of patches, this antenna can function without need for a power-division network (unless circular polarization is needed). The profile of this antenna is lower than that of a horn or a helical antenna designed for the same frequency. The primary disadvantage of this antenna, relative to a horn or a helical antenna, is that its footprint is slightly larger.

  16. Optical antenna enhanced spontaneous emission

    PubMed Central

    Eggleston, Michael S.; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C.

    2015-01-01

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼200 THz optical frequency show a spontaneous emission intensity enhancement of 35× corresponding to a spontaneous emission rate speedup ∼115×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼2,500× spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d2. Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, Io = qω|xo|/d, feeding the antenna-enhanced spontaneous emission, where q|xo| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency. PMID:25624503

  17. Optical antenna enhanced spontaneous emission

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eggleston, Michael S.; Messer, Kevin; Zhang, Liming

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ~200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ~115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ~2,500 × spontaneous emission speedup at d ~10 nm, proportional to 1/d 2. Unfortunately, at dmore » < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Additionally, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.« less

  18. Optical antenna enhanced spontaneous emission.

    PubMed

    Eggleston, Michael S; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C

    2015-02-10

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼ 200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ∼ 115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼ 2,500 × spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d(2). Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.

  19. Optical antenna enhanced spontaneous emission

    DOE PAGES

    Eggleston, Michael S.; Messer, Kevin; Zhang, Liming; ...

    2015-01-26

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ~200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ~115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ~2,500 × spontaneous emission speedup at d ~10 nm, proportional to 1/d 2. Unfortunately, at dmore » < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Additionally, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.« less

  20. A L-Band Superstrate Lens Enhanced Antenna and Array for Tactical Operations

    DTIC Science & Technology

    2013-07-01

    unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The design of a 1.2 GHz microstrip antenna utilizing a superstrate layer for gain enhancement is...CA, 92152-5001 sam.chieh@navy.mil Abstract—The design of a 1.2 GHz microstrip antenna utilizing a superstrate layer for gain enhancement is...realized. The microstrip patch antenna is a widely used antenna in this regime as it is light weight and is easily scalable for increased gains. It has

  1. Apparatus and Method for Improving the Gain and Bandwidth of a Microstrip Patch Antenna

    DTIC Science & Technology

    2013-09-30

    improving both the gain and the bandwidth of a microstrip patch antenna . (2) Description of the Prior Art [0004] A patch antenna , also referred to as a...rectangular microstrip antenna , is a type of radio antenna with a low profile that can be mounted on a flat surface. The patch antenna includes a...patch antenna form a Attorney Docket No. 101925 2 of 11 resonant piece of microstrip transmission line. The patch is designed to have a length of

  2. Experimental Study of RF Sheaths due to Shear Alfvén Waves in the LAPD

    NASA Astrophysics Data System (ADS)

    Martin, Michael; Gekelman, Walter; van Compernolle, Bart; Pribyl, Patrick; Carter, Troy

    2014-10-01

    Ion cyclotron resonance heating (ICRH) is an important tool in current fusion heating experiments and will be an essential part of heating power in ITER. Radio frequency (RF) sheaths in the near-field (at the antenna) and in the far-field (e.g. the divertor region) form during ICRH and may cause deleterious effects, such as destruction of wall materials and plasma impurity generation. In this study a shear Alfvén wave is launched from an antenna in the LAPD bulk plasma (ne ~ 1012 cm-3, Te ~ 5 eV, B0 = 1.8 kG, diameter = 60 cm, length = 18 m) and forms an RF sheath on a limiter plate. Plasma potential rectification is observed with an emissive probe in the bulk plasma only on field lines connected to the limiter. The largest enhancement occurs inside the current channel of the Alfvén wave. Plasma potential measurements at various axial distances from the limiter show the rectification decreases with distance. 2-D maps of plasma potential as well as E = - ∇Φ will be presented. The scaling of sheath potential with wave power and plasma parameters will also be shown.

  3. Determination of antenna factors using a three-antenna method at open-field test site

    NASA Astrophysics Data System (ADS)

    Masuzawa, Hiroshi; Tejima, Teruo; Harima, Katsushige; Morikawa, Takao

    1992-09-01

    Recently NIST has used the three-antenna method for calibration of the antenna factor of an antenna used for EMI measurements. This method does not require the specially designed standard antennas which are necessary in the standard field method or the standard antenna method, and can be used at an open-field test site. This paper theoretically and experimentally examines the measurement errors of this method and evaluates the precision of the antenna-factor calibration. It is found that the main source of the error is the non-ideal propagation characteristics of the test site, which should therefore be measured before the calibration. The precision of the antenna-factor calibration at the test site used in these experiments, is estimated to be 0.5 dB.

  4. SATCOM antenna siting study on P-3C aircraft, volume 2

    NASA Technical Reports Server (NTRS)

    Bensman, D. A.; Marhefka, R. J.

    1991-01-01

    This volume contains an antenna location study for the P-3C aircraft. From this location study, a determination can be made of the complete antenna system required to achieve the desired pattern and polarization coverage. The antenna used is the same Batwing airborne UHF satellite communications antenna use in volume 1. The aircraft model used in the majority of the locations studied is the simple cylindrical aircraft model defined in volume 1.

  5. 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

  6. Implantable ferrite antenna for biomedical applications

    NASA Astrophysics Data System (ADS)

    Fazeli, Maxwell L.

    We have developed an implantable microstrip patch antenna with dimensions of 10x10x1.28 mm, operating around the Industrial, Scientific and Medical (ISM) band (2.4-2.5 GHz). The antenna is characterized in skin-mimicking gels and compared with simulation results. The experimental measurements are in good agreement with simulations, having a -16 dB reflection coefficient and -18 dBi realized gain at resonance, with a 185 MHz -10 dB bandwidth. The simulated effects of ferrite film loading on antenna performance are investigated, with comparisons made for 5 and 10 microm thick films, as well as for 10 microm thick films with varying magnetic loss (tan delta micro = 0.05, 0.1 and 0.3). Our simulations reveal that the addition of 10 microm thick magnetic layers has effectively lowered the resonant frequency by 70 MHz, while improving return loss and -10 dB bandwidth by 3 dB and 40 MHz, respectively, over the uncoated antenna. Ferrite film coating also improved realized gain within the ISM band, with largest gain increases at resonance found for films having lower magnetic loss. Additionally, the gain (G) variance at ISM band limits, Delta Gf(2.5GHz)-f (2.4GHz), decreased from 1.97 to 0.44 dBi for the antenna with 10 microm films over the non-ferrite antenna. The measured dip-coated NiCo ferrite films effectively reduces the antenna resonance by 110 MHz, with a 4.2 dB reflection coefficient improvement as compared to an antenna without ferrite. The measured ferrite antenna also reveals a 6 dBi and 35 MHz improvement in realized gain and -10 dB bandwidth, respectively, at resonance. Additionally, the ferrite-coated antenna shows improved directivity, with wave propagation attenuated at the direction facing the body internal. These results indicate that implantable antenna miniaturization and reliable wireless communication in the operating frequency band can be realized with ferrite loading.

  7. Cassegrain antenna with a semitransparent secondary mirror.

    PubMed

    Caiyang, Weinan; Yang, Huajun; Jiang, Ping; He, Wensen; Tian, Yu; Chen, Xue

    2017-06-10

    With the help of the vector theory of reflection and refraction, a novel emitting Cassegrain antenna with a semitransparent secondary mirror has been proposed and analyzed for a distant point source. Based on the absorptivity valued at 3.00% and the reflectivity valued at 0.10%, this new emitting antenna can increase the transmission efficiency from 63.65% to 93.85%. In addition, an off-axis parabolic receiving antenna corresponding to the emitting antenna is designed and the 3D ray-trace simulation result is given. According to the simulation result, this receiving antenna can nicely converge the rays from the emitting antenna.

  8. Performance of a four-element Ka-band high-temperature superconducting microstrip antenna

    NASA Technical Reports Server (NTRS)

    Richard, M. A.; Bhasin, K. B.; Gilbert, C.; Metzler, S.; Koepf, G.; Claspy, P. C.

    1992-01-01

    Superconducting four-element microstrip array antennas operating at 30 GHz have been designed and fabricated on a lanthanum aluminate (LaAlO3) substrates. The experimental performance of these thin film Y-Ba-Cu-O superconducting antennas is compared with that of identical antenna patterned with evaporated gold. Efficiency measurements of these antennas show an improvement of 2 dB at 70 K and as much as 3.5 dB at 40 K in the superconducting antenna over the gold antenna.

  9. A Meta-Surface Antenna Array Decoupling (MAAD) Method for Mutual Coupling Reduction in a MIMO Antenna System.

    PubMed

    Wang, Ziyang; Zhao, Luyu; Cai, Yuanming; Zheng, Shufeng; Yin, Yingzeng

    2018-02-16

    In this paper, a method to reduce the inevitable mutual coupling between antennas in an extremely closely spaced two-element MIMO antenna array is proposed. A suspended meta-surface composed periodic square split ring resonators (SRRs) is placed above the antenna array for decoupling. The meta-surface is equivalent to a negative permeability medium, along which wave propagation is rejected. By properly designing the rejection frequency band of the SRR unit, the mutual coupling between the antenna elements in the MIMO antenna system can be significantly reduced. Two prototypes of microstrip antenna arrays at 5.8 GHz band with and without the metasurface have been fabricated and measured. The matching bandwidths of antennas with reflection coefficient smaller than -15 dB for the arrays without and with the metasurface are 360 MHz and 900 MHz respectively. Using the meta-surface, the isolation between elements is increased from around 8 dB to more than 27 dB within the band of interest. Meanwhile, the total efficiency and peak gain of each element, the envelope correlation coefficient (ECC) between the two elements are also improved by considerable amounts. All the results demonstrate that the proposed method is very efficient for enhancing the performance of MIMO antenna arrays.

  10. Slotted Antenna with Anisotropic Magnetic Loading

    DTIC Science & Technology

    2016-07-26

    10 SLOTTED ANTENNA WITH ANISOTROPIC MAGNETIC LOADING STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured...is directed to a slotted antenna having enhanced broadband characteristics. (2) Description of the Prior Art [0004] Slotted cylinder antennas are...popular antennas for use in line of sight communications systems, especially where the carrier frequency exceeds 300 MHz. FIG. 1 provides a diagram

  11. Design, simulation and analysis a microstrip antenna using PU-EFB substrate

    NASA Astrophysics Data System (ADS)

    Mahmud, S. N. S.; Jusoh, M. A.; Jasim, S. E.; Zamani, A. H.; Abdullah, M. H.

    2018-04-01

    A low cost, light weight and easy to fabricate are the most important factor for future antennas. Microstrip patch antennas offer these advantages and suitable for communication and sensor application. This paper presents a design of simple microstrip patch antenna working on operating frequency of 2.4 GHz. The designed process has been carried out using MATLAB and HFSS software by entering 2.3 for the dielectric constant of PU-EFB. The results showed that high return loss, low bandwidth and good antenna radiation efficiency of which are -21.98 dB, 0.28 dB and 97.33%, respectively.

  12. Antenna for passive RFID tags

    NASA Astrophysics Data System (ADS)

    Schiopu, Paul; Manea, Adrian; Cristea, Ionica; Grosu, Neculai; Vladescu, Marian; Craciun, Anca-Ileana; Craciun, Alexandru

    2015-02-01

    Minuscule devices, called RFID tags are attached to objects and persons and emit information which positioned readers may capture wirelessly. Many methods of identification have been used, but that of most common is to use a unique serial number for identification of person or object. RFID tags can be characterized as either active or passive [1,2]. Traditional passive tags are typically in "sleep" state until awakened by the reader's emitted field. In passive tags, the reader's field acts to charge the capacitor that powers the badge and this can be a combination of antenna and barcodes obtained with SAW( Surface Acoustic Wave) devices [1,2,3] . The antenna in an RFID tag is a conductive element that permits the tag to exchange data with the reader. The paper contribution are targeted to antenna for passive RFID tags. The electromagnetic field generated by the reader is somehow oriented by the reader antenna and power is induced in the tag only if the orientation of the tag antenna is appropriate. A tag placed orthogonal to the reader yield field will not be read. This is the reason that guided manufacturers to build circular polarized antenna capable of propagating a field that is alternatively polarized on all planes passing on the diffusion axis. Passive RFID tags are operated at the UHF frequencies of 868MHz (Europe) and 915MHz (USA) and at the microwave frequencies of 2,45 GHz and 5,8 GHz . Because the tags are small dimensions, in paper, we present the possibility to use circular polarization microstrip antenna with fractal edge [2].

  13. One antenna, two antennae, big antennae, small: total antennae length, not bilateral symmetry, predicts odor-tracking performance in the American cockroach Periplaneta americana.

    PubMed

    Lockey, Jacob K; Willis, Mark A

    2015-07-01

    Determining the location of a particular stimulus is often crucial to an animal's survival. One way to determine the local distribution of an odor is to make simultaneous comparisons across multiple sensors. If the sensors detect differences in the distribution of an odor in space, the animal can then steer toward the source. American cockroaches, Periplaneta americana, have 4 cm long antennae and are thought to track odor plumes using a spatial sampling strategy, comparing the amount of odor detected between these bilateral sensors. However, it is not uncommon for cockroaches to lose parts of their antennae and still track a wind-borne odor to its source. We examined whether bilateral odor input is necessary to locate an odor source in a wind-driven environment and how the loss of increasing lengths of the antennae affects odor tracking. The tracking performances of individuals with two bilaterally symmetrical antennae of decreasing length were compared with antennal length-matched individuals with one antenna. Cockroaches with one antenna were generally able to track an odor plume to its source. In fact, the performances of unilaterally antennectomized individuals were statistically identical to those of their bilaterally symmetrical counterparts when the combined length of both antennae equaled the length of the single antenna of the antennectomized individuals. This suggests that the total length of available antennae influences odor tracking performance more than any specific piece of antenna, and that they may be doing something more complex than a simple bilateral comparison between their antennae. The possibility of an antenna-topic map is discussed. © 2015. Published by The Company of Biologists Ltd.

  14. A survey of various enhancement techniques for square rings antennas

    NASA Astrophysics Data System (ADS)

    Mumin, Abdul Rashid O.; Alias, Rozlan; Abdullah, Jiwa; Abdulhasan, Raed Abdulkareem; Ali, Jawad; Dahlan, Samsul Haimi; Awaleh, Abdisamad A.

    2017-09-01

    The square ring shape becomes a famous reconfiguration on antenna design. The researchers have been developed the square ring by different configurations. It has high efficiency and simple calculation method. The performance enhancement for an antenna is the main reason to use this setting. Furthermore, the multi-objectives for the antenna also are considered. In this paper, different studies of square ring shape are discussed. This shape is developed in five different techniques, which are the gain enhancement, dual band antenna, reconfigurable antenna, CSRR, and circularly polarization. Moreover, the validation between these configurations also demonstrates for square ring shapes. In particular, the square ring slot improved the gain by 4.3 dB, provide dual band resonance at 1.4 and 2.6 GHz while circular polarization at 1.54 GHz, and multi-mode antenna. However, square ring strip achieved an excellent band rejection on UWB antenna at 5.5 GHz. The square ring slot length is the most influential factor on the antenna performance, which refers to the free space wavelength. Finally, comparisons between these techniques are presented.

  15. Slotted Antenna with Uniaxial Dielectric Covering

    DTIC Science & Technology

    2016-07-08

    1 of 12 SLOTTED ANTENNA WITH UNIAXIAL DIELECTRIC COVERING STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be...invention is directed to a slotted antenna having enhanced broadband characteristics. (2) Description of the Prior Art [0004] Slotted cylinder antennas ...slotted cylinder antenna for use in a towed buoy. Though somewhat broadband in performance, it is not suitable for vertical mounting over a

  16. Non-Uniform Bias Enhancement of a Varactor-Tuned FSS used with a Low Profile 2.4 GHz Dipole Antenna

    NASA Technical Reports Server (NTRS)

    Cure, David; Weller, Thomas M.; Miranda, Felix A.

    2012-01-01

    In this paper a low profile antenna using a nonuniformly biased varactor-tuned frequency selective surface (FSS) is presented. The tunable FSS avoids the use of vias and has a simplified DC bias network. The voltages to the DC bias ports can be varied independently allowing adjustment in the frequency response and enhanced radiation properties. The measured data demonstrate tunability from 2.15 GHz to 2.63 GHz with peak efficiencies that range from 50% to 90% and instantaneous bandwidths of 50 MHz to 280 MHz within the tuning range. The total antenna thickness is approximately lambda/45.

  17. Reconfigurable antenna pattern verification

    NASA Technical Reports Server (NTRS)

    Drexler, Jerome P. (Inventor); Becker, Robert C. (Inventor); Meyers, David W. (Inventor); Muldoon, Kelly P. (Inventor)

    2013-01-01

    A method of verifying programmable antenna configurations is disclosed. The method comprises selecting a desired antenna configuration from a plurality of antenna configuration patterns, with the selected antenna configuration forming at least one reconfigurable antenna from reconfigurable antenna array elements. The method validates the formation of the selected antenna configuration to determine antenna performance of the at least one reconfigurable antenna.

  18. Progress in integrated-circuit horn antennas for receiver applications. Part 2: A 90 GHz quasi-integrated horn antenna receiver

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    A receiver belonging to the family of integrated planar receivers has been developed at 90 GHz. It consists of a planar Schottky-diode placed at the feed of a dipole-probe suspended inside an integrated horn antenna. The measured planar mixer single-sideband conversion loss at 91.2 GHz (LO) with a 200 MHz IF frequency is 8.3dB plus or minus 0.3dB. The low cost of fabrication and simplicity of this design makes it ideal for millimeter and submillimeter-wave receivers.

  19. Broadband Pillbox Antennas.

    DTIC Science & Technology

    1984-09-21

    Identify by block number) - FIELD GROUP SUB-GROUP Double layer pillbox antennas Triple layer pillbox antenna The possibility of designing very broadband... Design .................... 1 Broadband Feed De gn ........................................... 2 Ex mental Simulation of Double Layer Pillbox...5 REFERENCES ................................................... 6 APPENDIX - COAXIAL TO WAVEGUIDE JUNCTION DESIGN

  20. A High Power Helicon Antenna Design for DIII-D

    DOE PAGES

    Nagy, A.; deGrassie, J.; Moeller, C.; ...

    2017-08-02

    A new antenna design for driving current in high beta tokamaks using electromagnetic waves, called Helicons, will be experimentally tested for the first time at power approaching 1 megawatt (MW) in the DIII-D Tokamak. This method is expected to be more efficient than current drive using electron cyclotron waves or neutral beam injection, and may be well suited to reactor-like configurations. A low power (100 watt (W)) 476 megahertz (MHz) “comb-line” antenna, consisting of 12 inductively coupled electrostatically shielded, modular resonators, was tested in DIII-D and showed strong coupling to the plasma without disturbing its characteristics or introducing metal impurities.more » The high power antenna consists of 30 modules affixed to back-plates and mounted on the outer wall of the vacuum vessel above the mid-plane. The antenna design follows a similar low power antenna design modified to minimize RF loss. Heat removal is provided by water cooling and a novel heat conducting path using pyrolytic graphite sheet. The CuCrZr antenna modules are designed to handle high eddy current forces. The modules use molybdenum Faraday shields that have the plasma side coated with boron carbide to enhance thermal resistance and minimize high Z impurities. A RF strip-line feed routes the RF power from coaxial vacuum feed-throughs to the antenna. Multipactor analysis of the antenna, strip line, and feedthrough will be performed. A 1.2 MW, 476 MHz klystron system, provided by the Stanford Linear Accelerator (SLAC) will provide RF power to the new antenna. Lastly, a description of the design of the high power antenna, the RF strip-line feeds, and the vessel installation will be presented.« less

  1. A High Power Helicon Antenna Design for DIII-D

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nagy, A.; deGrassie, J.; Moeller, C.

    A new antenna design for driving current in high beta tokamaks using electromagnetic waves, called Helicons, will be experimentally tested for the first time at power approaching 1 megawatt (MW) in the DIII-D Tokamak. This method is expected to be more efficient than current drive using electron cyclotron waves or neutral beam injection, and may be well suited to reactor-like configurations. A low power (100 watt (W)) 476 megahertz (MHz) “comb-line” antenna, consisting of 12 inductively coupled electrostatically shielded, modular resonators, was tested in DIII-D and showed strong coupling to the plasma without disturbing its characteristics or introducing metal impurities.more » The high power antenna consists of 30 modules affixed to back-plates and mounted on the outer wall of the vacuum vessel above the mid-plane. The antenna design follows a similar low power antenna design modified to minimize RF loss. Heat removal is provided by water cooling and a novel heat conducting path using pyrolytic graphite sheet. The CuCrZr antenna modules are designed to handle high eddy current forces. The modules use molybdenum Faraday shields that have the plasma side coated with boron carbide to enhance thermal resistance and minimize high Z impurities. A RF strip-line feed routes the RF power from coaxial vacuum feed-throughs to the antenna. Multipactor analysis of the antenna, strip line, and feedthrough will be performed. A 1.2 MW, 476 MHz klystron system, provided by the Stanford Linear Accelerator (SLAC) will provide RF power to the new antenna. Lastly, a description of the design of the high power antenna, the RF strip-line feeds, and the vessel installation will be presented.« less

  2. A 2×1 Coplanar Monopole Antenna Structure for Wireless RF Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Mathur, Monika; Agarwal, Ankit; Singh, Ghanshyam; Bhatnagar, S. K.

    2018-03-01

    The objective of this paper is to design an efcient wireless energy harvesting (WEH) system to eliminate the problem to continuous charging of a battery operated electronics devices. Most of the devices are battery operated so charging of a battery time to time is serious issue. This WEH system receives the Radio Frequency (RF) and Microwave frequency signals present in the atmosphere and converting it into DC signal so that it can stores in Capacitor or charges a battery for utilize the power. For this RF energy harvesting purposes 21 antenna array structure of the coplanar monopole antenna is presented. This structure shows the gain of 10.2 dBi and 83% efciency. This structure is designed for resonating on multiple bands (Radio, GSM, ISM, and UWB). It is useful for this application because it covers almost all useful bands in the maximum capturing area. The antenna can be connected directly to an RF-DC converter module and it uses about 60% of the total PCB area. And RF to DC convertor circuit can be implemented in that remaining 40% area on the same substrate so it eliminates the need of port connectors and impedance matching circuit between them. This design is worked in receiving mode only when used for energy harvesting purposes. This may be useful for the biomedical and satellite applications.

  3. Broadband Circularly Polarized Patch Antenna and Method

    DTIC Science & Technology

    2016-09-16

    300152 1 of 14 BROADBAND CIRCULARLY POLARIZED PATCH ANTENNA AND METHOD STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may...present invention provides a method and apparatus for a broadband circularly polarized patch antenna . (2) Description of the Prior Art [0004] A...patch antenna , also referred to as a microstrip antenna , is a type of radio antenna with a low profile that can be mounted on a flat surface. The

  4. Shear sensing based on a microstrip patch antenna

    NASA Astrophysics Data System (ADS)

    Mohammad, I.; Huang, H.

    2012-10-01

    A microstrip patch antenna sensor was studied for shear sensing with a targeted application of measuring plantar shear distribution on a diabetic foot. The antenna shear sensor consists of three components, namely an antenna patch, a soft foam substrate and a slotted ground plane. The resonant frequency of the antenna sensor is sensitive to the overlapping length between the slot in the ground plane and the antenna patch. A shear force applied along the direction of the slot deforms the foam substrate and causes a change in the overlapping length, which can be detected from the antenna frequency shift. The antenna shear sensor was designed based on simulated antenna frequency response and validated by experiments. Experimental results indicated that the antenna sensor exhibits high sensitivity to shear deformation and responds to the applied shear loads with excellent linearity and repeatability.

  5. Ultrawideband combined antenna with improved matching

    NASA Astrophysics Data System (ADS)

    Balzovsky, E. V.; Buyanov, Yu I.; Koshelev, V. I.; Nekrasov, E. S.

    2018-05-01

    To study the immunity of electronic equipment to ultrawideband irradiation, a combined antenna with improved matching has been created. In contrast to the previously presented, a novel antenna has a modified input node with a flat part instead of a cylindrical one. As a result of optimizing the geometry of the antenna electrodes, a matching band with the feeder of 0.38-2.4 GHz was achieved by the VSWR = 2. The results of the investigations of antenna characteristics in the frequency domain, as well as the waveforms of the radiated short ultrawideband pulses are presented.

  6. Plasma current ramp-up by lower hybrid wave using innovative antennas on TST-2

    NASA Astrophysics Data System (ADS)

    Takase, Yuichi; Ejiri, Akira; Moeller, Charles; Roidl, Benedikt; Shinya, Takahiro; Tsujii, Naoto; Yajima, Satoru; Yamazaki, Hibiki; Kitayama, Akichika; Matsumoto, Naoki; Sato, Akito; Sonehara, Masateru; Takahashi, Wataru; Tajiri, Yoshiyuki; Takei, Yuki; Togashi, Hiro; Toida, Kazuya; Yoshida, Yusuke

    2016-10-01

    Non-inductive plasma current (Ip) ramp-up by RF power in the lower hybrid frequency range is being studied on the TST-2 spherical tokamak (R = 0.36 m, a = 0.23 m, Bt = 0.3 T, Ip = 0.1 MA). Up to 400 kW of RF power is available at a frequency of 200 MHz. An innovative antenna called the capacitively-coupled combline (CCC) antenna was developed to excite a sharp, highly directional traveling wave with the electric field polarized in the toroidal direction. It is an array of resonant circuit elements made of capacitance and inductance, coupled to neighboring elements by mutual capacitance. Two CCC antennas are installed in TST-2, a 13-element outboard-launch antenna and a 6-element top-launch antenna. The latter was installed in March 2016 to improve accessibility to the core and to achieve single-pass damping. The suspected wave power loss in the scrape-off layer plasma should also be avoided. Ip ramp-up to 25 kA has been achieved so far. An upgrade of the Bt power supply is planned to take advantage of the observed improvement of Ip ramp-up with Bt. Higher Bt for longer pulses should improve the Ip ramp-up efficiency by improving wave accessibility and by reducing prompt orbit losses of energetic electrons.

  7. Enhanced coherent terahertz beam with a photoconductive antenna containing a chaotic shape electrodes

    NASA Astrophysics Data System (ADS)

    Wu, Dong Ho; Kim, Christopher; Graber, Benjamin

    2014-03-01

    Photoconductive antenna is one of the most popular methods to produce a broadband terahertz beam. Our recent experiments indicate that a photoconductive antenna containing a pair of parallel micro-strip-line electrodes produces both incoherent and coherent terahertz beam. When we drive the antenna with a low bias voltage and a weak femto-second laser power, it produces mostly coherent terahertz beam. However, as the bias voltage and/or the femto-second laser power increase, the incoherent terahertz beam strength increases exponentially with the bias voltage.[1] When the bias voltage and/or the femto-second laser power exceeds critical values, heat associated with the incoherent beam eventually leads to a catastrophic antenna failure, resulting in a permanent damage on the antenna.[2] In order to improve our photoconductive antenna we have implemented a chaotic geometry in the photoconductive antenna's electrodes. Our experimental results show that the new antenna produces substantially more coherent terahertz beam and much less incoherent terahertz beam. We will present the details of our experimental results and discuss the merits of new antenna design. We will also examine some theory to understand our experimental results. Supported by DTRA.

  8. Analysis of a microstrip reflectarray antenna for microspacecraft applications

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1995-01-01

    A microstrip reflectarray is a flat reflector antenna that can be mounted conformally onto a spacecraft's outside structure without consuming a significant amount of spacecraft volume and mass. For large apertures (2 m or larger), the antenna's reflecting surface, being flat, can be more easily and reliably deployed than a curved parabolic reflector. This article presents the study results on a microstrip reflect-array with circular polarization. Its efficiency and bandwidth characteristics are analyzed. Numerous advantages of this antenna system are discussed. Three new concepts using this microstrip reflectarray are also proposed.

  9. From antenna to antenna: lateral shift of olfactory memory recall by honeybees.

    PubMed

    Rogers, Lesley J; Vallortigara, Giorgio

    2008-06-04

    Honeybees, Apis mellifera, readily learn to associate odours with sugar rewards and we show here that recall of the olfactory memory, as demonstrated by the bee extending its proboscis when presented with the trained odour, involves first the right and then the left antenna. At 1-2 hour after training using both antennae, recall is possible mainly when the bee uses its right antenna but by 6 hours after training a lateral shift has occurred and the memory can now be recalled mainly when the left antenna is in use. Long-term memory one day after training is also accessed mainly via the left antenna. This time-dependent shift from right to left antenna is also seen as side biases in responding to odour presented to the bee's left or right side. Hence, not only are the cellular events of memory formation similar in bees and vertebrate species but also the lateralized networks involved may be similar. These findings therefore seem to call for remarkable parallel evolution and suggest that the proper functioning of memory formation in a bilateral animal, either vertebrate or invertebrate, requires lateralization of processing.

  10. Rigorous analysis of thick microstrip antennas and wire antennas embedded in a substrate

    NASA Astrophysics Data System (ADS)

    Smolders, A. B.

    1992-07-01

    An efficient and rigorous method for the analysis of electrically thick rectangular microstrip antennas and wire antennas with a dielectric cover is presented. The method of moments is used in combination with the exact spectral domain Green's function in order to find the unknown currents on the antenna. The microstrip antenna is fed by a coaxial cable. A proper model of the feeding coaxial structure is used. In addition, a special attachment mode was applied to ensure continuity of current at the patch-coax transition. The efficiency of the method of moments is improved by using the so called source term extraction technique, where a great part of the infinite integrals involved with the method of moment formulation is calculated analytically. Computation time can be saved by selecting a set of basis functions that describes the current distribution on the patch and probe in an accurate way using only a few terms of this set. Thick microstrip antennas have broadband characteristics. However, a proper match to 50 Ohms is often difficult. This matching problem can be avoided by using a slightly different excitation structure. The patch is now electromagnetically coupled to the feeding probe. A bandwidth of more than 40 can easily be obtained for this type of microstrip antenna. The price to be paid is a degradation of the radiation characteristics.

  11. High-resolution T2-weighted cervical cancer imaging: a feasibility study on ultra-high-field 7.0-T MRI with an endorectal monopole antenna.

    PubMed

    Hoogendam, Jacob P; Kalleveen, Irene M L; de Castro, Catalina S Arteaga; Raaijmakers, Alexander J E; Verheijen, René H M; van den Bosch, Maurice A A J; Klomp, Dennis W J; Zweemer, Ronald P; Veldhuis, Wouter B

    2017-03-01

    We studied the feasibility of high-resolution T 2 -weighted cervical cancer imaging on an ultra-high-field 7.0-T magnetic resonance imaging (MRI) system using an endorectal antenna of 4.7-mm thickness. A feasibility study on 20 stage IB1-IIB cervical cancer patients was conducted. All underwent pre-treatment 1.5-T MRI. At 7.0-T MRI, an external transmit/receive array with seven dipole antennae and a single endorectal monopole receive antenna were used. Discomfort levels were assessed. Following individualised phase-based B 1 + shimming, T 2 -weighted turbo spin echo sequences were completed. Patients had stage IB1 (n = 9), IB2 (n = 4), IIA1 (n = 1) or IIB (n = 6) cervical cancer. Discomfort (ten-point scale) was minimal at placement and removal of the endorectal antenna with a median score of 1 (range, 0-5) and 0 (range, 0-2) respectively. Its use did not result in adverse events or pre-term session discontinuation. To demonstrate feasibility, T 2 -weighted acquisitions from 7.0-T MRI are presented in comparison to 1.5-T MRI. Artefacts on 7.0-T MRI were due to motion, locally destructive B 1 interference, excessive B 1 under the external antennae and SENSE reconstruction. High-resolution T 2 -weighted 7.0-T MRI of stage IB1-IIB cervical cancer is feasible. The addition of an endorectal antenna is well tolerated by patients. • High resolution T 2 -weighted 7.0-T MRI of the inner female pelvis is challenging • We demonstrate a feasible approach for T 2 -weighted 7.0-T MRI of cervical cancer • An endorectal monopole receive antenna is well tolerated by participants • The endorectal antenna did not lead to adverse events or session discontinuation.

  12. Study of array plasma antenna parameters

    NASA Astrophysics Data System (ADS)

    Kumar, Rajneesh; Kumar, Prince

    2018-04-01

    This paper is aimed to investigate the array plasma antenna parameters to help the optimization of an array plasma antenna. Single plasma antenna is transformed into array plasma antenna by changing the operating parameters. The re-configurability arises in the form of striations, due to transverse bifurcation of plasma column by changing the operating parameters. Each striation can be treated as an antenna element and system performs like an array plasma antenna. In order to achieve the goal of this paper, three different configurations of array plasma antenna (namely Array 1, Array 2 and Array 3) are simulated. The observations are made on variation in antenna parameters like resonance frequency, radiation pattern, directivity and gain with variation in length and number of antenna elements for each array plasma antenna. Moreover experiments are also performed and results are compared with simulation. Further array plasma antenna parameters are also compared with monopole plasma antenna parameters. The study of present paper invoke the array plasma antenna can be applied for steering and controlling the strength of Wi-Fi signals as per requirement.

  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. A dual-band near-field focused reflectarray antenna for RFID applications at 0.9 and 2.4 GHz

    NASA Astrophysics Data System (ADS)

    Chou, Hsi-Tseng; Hsueh, Pai-Han; Hung, Tso-Ming; Kuo, Li-Ruei; Chou, Hsi-Hsir

    2011-12-01

    This paper presents a dual-band reflectarray antenna which operates at 0.915 and 2.4 GHz to radiate electromagnetic fields focused in the near-zone of array aperture. The design uses two stacked feed antennas operated at 0.915 and 2.4 GHz, respectively, so that the currently available RFID systems in the market can be simultaneously used in an independent fashion. Numerical investigations on the radiation characteristics of this reflectarray, as well as an experimental validation, are presented to demonstrate its feasibility.

  15. 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.

  16. A Wideband Circularly Polarized Antenna with a Multiple-Circular-Sector Dielectric Resonator.

    PubMed

    Trinh-Van, Son; Yang, Youngoo; Lee, Kang-Yoon; Hwang, Keum Cheol

    2016-11-03

    This paper presents the design of a wideband circularly polarized antenna using a multiple-circular-sector dielectric resonator (DR). The DR is composed of twelve circular-sector DRs with identical central angles of 30 ∘ but with different radii. A genetic algorithm is utilized to optimize the radii of the twelve circular-sector DRs to realize wideband circular polarization. The proposed antenna is excited using an aperture-coupled feeding technique through a narrow rectangular slot etched onto the ground plane. An antenna prototype is experimentally verified. The measured -10 dB reflection and 3 dB axial ratio (AR) bandwidths are 31.39% (1.88-2.58 GHz) and 19.30% (2.06-2.50 GHz), respectively, covering the operating bands of the following systems: UMTS-2100 (2.145 GHz), WiMAX (2.3 GHz), and Wi-Fi (2.445 GHz). A measured peak gain of 7.65 dBic at 2.225 GHz and gain variation of less than 2.70 dBic within the measured 3 dB AR bandwidth are achieved. In addition, the radiation patterns of the proposed antenna are presented and discussed.

  17. A Wideband Circularly Polarized Antenna with a Multiple-Circular-Sector Dielectric Resonator

    PubMed Central

    Trinh-Van, Son; Yang, Youngoo; Lee, Kang-Yoon; Hwang, Keum Cheol

    2016-01-01

    This paper presents the design of a wideband circularly polarized antenna using a multiple-circular-sector dielectric resonator (DR). The DR is composed of twelve circular-sector DRs with identical central angles of 30∘ but with different radii. A genetic algorithm is utilized to optimize the radii of the twelve circular-sector DRs to realize wideband circular polarization. The proposed antenna is excited using an aperture-coupled feeding technique through a narrow rectangular slot etched onto the ground plane. An antenna prototype is experimentally verified. The measured −10 dB reflection and 3 dB axial ratio (AR) bandwidths are 31.39% (1.88–2.58 GHz) and 19.30% (2.06–2.50 GHz), respectively, covering the operating bands of the following systems: UMTS-2100 (2.145 GHz), WiMAX (2.3 GHz), and Wi-Fi (2.445 GHz). A measured peak gain of 7.65 dBic at 2.225 GHz and gain variation of less than 2.70 dBic within the measured 3 dB AR bandwidth are achieved. In addition, the radiation patterns of the proposed antenna are presented and discussed. PMID:27827881

  18. Miniaturization of Microwave Ablation Antennas

    NASA Astrophysics Data System (ADS)

    Luyen, Hung

    Microwave ablation (MWA) is a promising minimally invasive technique for the treatment of various types of cancers as well as non-oncological diseases. In MWA, an interstitial antenna is typically used to deliver microwave energy to the diseased tissue and heat it up to lethal temperature levels that induce cell death. The desired characteristics of the interstitial antenna include a narrow diameter to minimize invasiveness of the treatment, a low input reflection coefficient at the operating frequency, and a localized heating zone. Most interstitial MWA antennas are fed by coaxial cables and designed for operation at either 915 MHz or 2.45 GHz. Coax-fed MWA antennas are commonly equipped with coaxial baluns to achieve localized heating. However, the conventional implementation of coaxial baluns increases the overall diameters of the antennas and therefore make them more invasive. It is highly desirable to develop less invasive antennas with shorter active lengths and smaller diameters for MWA applications. In this work, we demonstrate the feasibility of using higher frequency microwaves for tissue ablation and present several techniques for decreasing diameters of MWA antennas. First, we investigated MWA at higher frequencies by conducting numerical and experimental studies to compare ablation performance at 10 GHz and 1.9 GHz. Simulation and ex vivo ablation experiment results demonstrate comparable ablation zone dimensions achieved at these two frequencies. Operating at higher frequencies enables interstitial antennas with shorter active lengths. This can be combined with smaller-diameter antenna designs to create less invasive applicators or allow integration of multiple radiating elements on a single applicator to have better control and customization of the heating patterns. Additionally, we present three different coax-fed antenna designs and a non-coaxial-based balanced antenna that have smaller-diameter configurations than conventional coax-fed balun

  19. 47 CFR 74.641 - Antenna systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... elevation planes. (2) New periscope antenna systems will be authorized upon a certification that the... receiving antennas is left to the discretion of the licensee. However, licensees will not be protected from... congestion and must employ a Category A antenna when: (1) A showing by an applicant of a new TV auxiliary...

  20. Microrectenna: A Terahertz Antenna and Rectifier on a Chip

    NASA Technical Reports Server (NTRS)

    Siegel, Peter

    2007-01-01

    A microrectenna that would operate at a frequency of 2.5 THz has been designed and partially fabricated. The circuit is intended to be a prototype of an extremely compact device that could be used to convert radio-beamed power to DC to drive microdevices (see Figure 1). The microrectenna (see Figure 2) circuit consists of an antenna, a diode rectifier and a DC output port. The antenna consists of a twin slot array in a conducting ground plane (denoted the antenna ground plane) over an enclosed quarter-wavelength-thick resonant cavity (denoted the reflecting ground plane). The circuit also contains a planar high-frequency low-parasitic Schottky-barrier diode, a low-impedance microstrip transmission line, capacitors, and contact beam leads. The entire 3-D circuit is fabricated monolithically from a single GaAs wafer. The resonant cavity renders the slot radiation pattern unidirectional with a half-power beam width of about 65. A unique metal mesh on the rear of the wafer forms the backplate for the cavity but allows the GaAs to be wet etched from the rear surface of the twin slot antennas and ground plane. The beam leads protrude past the edge of the chip and are used both to mount the microrectenna and to make the DC electrical connection with external circuitry. The antenna ground plane and the components on top of it are formed on a 2- m thick GaAs membrane that is grown in the initial wafer MBE (molecular beam epitaxy) process. The side walls of the antenna cavity are not metal coated and, hence, would cause some loss of power; however, the relatively high permittivity (epsilon=13) of the GaAs keeps the cavity modes well confined, without the usual surface-wave losses associated with thick dielectric substrates. The Schottky-barrier diode has the usual submicron dimensions associated with THz operation and is formed in a mesa process above the antenna ground plane. The diode is connected at the midpoint of a microstrip transmission line, which is formed on 1- m

  1. Evaluation of detectable angle of mid-infrared slot antennas

    NASA Astrophysics Data System (ADS)

    Obara, R.; Horikawa, J.; Shimakage, H.; Kawakami, A.

    2017-07-01

    For evaluations of a mid-infrared (MIR) detectors with antenna, we constructed an angular dependence measurement system of the antenna properties. The fabricated MIR detector consisted of twin slot antennas and a bolometer. The area of the slot antennas was designed to be 2.6 × 0.2 μm2 as to resonate at 61 THz, and they were located parallel and separated 1.6 μm each other. The bolometer was fabricated using by a 7.0-nm thick NbN thin film, and located at the center of the twin antennas. We measured polarization angle dependence and directivity, and showed that the MIR antennas have polarization dependence and directivity like radiofrequency antennas.

  2. Thin-Wire Modeling Techniques Applied to Antenna Analysis.

    DTIC Science & Technology

    1974-10-11

    Ol- MULT11 CRN LOOP ANTENNA ... 30 2.4.1 Balanced vs unbalanced operation ... 3 1 2.4.2 Horizontal vs vertical configuration ... 33 3.0...of the Ml A-l Mimloop ... 28 Hl; multiturn loop antenna of Ohio State University ...31 Configurations ot balanced and unbalanced MTLs ... 32...4. Evaluation of Multiturn Loop Antenna In each example the specific project is outlined and the antenna analysis problems of particular interest

  3. Design And Simulation Of Microstrip Antenna Of 2.4 GHz Using CST

    NASA Astrophysics Data System (ADS)

    Thakur, O. P.; Kushwaha, Alok K.

    2011-12-01

    This article describes the design, fabrication and testing of micro strip patch antennas operating at 2.4 GHz. Consideration is given on practical design technique, including substrate selection and antenna measurements. It is emphasised to the radiation properties of the antennas—the radiation pattern and polarization purity. A micro strip patch antenna consists of a very thin metallic patch placed a small fraction of a wavelength above a conducting ground-plane. The patch and ground-plane are separated by a dielectric. The patch conductor is normally copper and can assume any shape, but simple geometries generally are used, and this simplifies the analysis and performance prediction. The patches are usually photo etched on the dielectric substrate. The substrate is usually non-magnetic. The relative permittivity of the substrate is normally in the region between 1 and 4, which enhances the fringing fields that account for radiation, but higher values may be used in special circumstances. Due to its simple geometry, the half wave rectangular patch is the most commonly used micro strip antenna. It is characterized by its length L, width w and thickness h. The simplest method of feeding the patch is by a coplanar micro strip line, also photo etched on the substrate. Coaxial feeds are also widely used.

  4. Recent advances in physics and technology of ion cyclotron resonance heating in view of future fusion reactors

    NASA Astrophysics Data System (ADS)

    Ongena, J.; Messiaen, A.; Kazakov, Ye O.; Koch, R.; Ragona, R.; Bobkov, V.; Crombé, K.; Durodié, F.; Goniche, M.; Krivska, A.; Lerche, E.; Louche, F.; Lyssoivan, A.; Vervier, M.; Van Eester, D.; Van Schoor, M.; Wauters, T.; Wright, J.; Wukitch, S.

    2017-05-01

    Ion temperatures of over 100 million degrees need to be reached in future fusion reactors for the deuterium-tritium fusion reaction to work. Ion cyclotron resonance heating (ICRH) is a method that has the capability to directly heat ions to such high temperatures, via a resonant interaction between the plasma ions and radiofrequency waves launched in the plasma. This paper gives an overview of recent developments in this field. In particular a novel and recently developed three-ion heating scenario will be highlighted. It is a flexible scheme with the potential to accelerate heavy ions to high energies in high density plasmas as expected for future fusion reactors. New antenna designs will be needed for next step large future devices like DEMO, to deliver steady-state high power levels, cope with fast variations in coupling due to fast changes in the edge density and to reduce the possibility for impurity production. Such a new design is the traveling wave antenna (TWA) consisting of an array of straps distributed around the circumference of the machine, which is intrinsically resilient to edge density variations and has an optimized power coupling to the plasma. The structure of the paper is as follows: to provide the general reader with a basis for a good understanding of the later sections, an overview is given of wave propagation, coupling and RF power absorption in the ion cyclotron range of frequencies, including a brief summary of the traditionally used heating scenarios. A special highlight is the newly developed three-ion scenario together with its promising applications. A next section discusses recent developments to study edge-wave interaction and reduce impurity influx from ICRH: the dedicated devices IShTAR and Aline, field aligned and three-strap antenna concepts. The principles behind and the use of ICRH as an important option for first wall conditioning in devices with a permanent magnetic field is discussed next. The final section presents ongoing

  5. Porous textile antenna designs for improved wearability

    NASA Astrophysics Data System (ADS)

    Shahariar, Hasan; Soewardiman, Henry; Muchler, Clifford A.; Adams, Jacob J.; Jur, Jesse S.

    2018-04-01

    Textile antennas are an integral part of the next generation personalized wearable electronics system. However, the durability of textile antennas are rarely discussed in the literature. Typical textile antennas are prone to damage during normal wearable user scenarios, washing, and heat cycling over time. Fabricating a durable, washable, flexible, and breathable (like textile materials) antenna is challenging due to the incompatibility of the mechanical properties of conductive materials and soft textile materials. This paper describes a scalable screen printing process on an engineered nonwoven substrate to fabricate microstrip patch antennas with enhanced durability. This work used an Evolon® nonwoven substrate with low surface roughness (˜Ra = 18 μm) and high surface area (˜2.05 mm2 mm-2 of fabric area) compared to traditional textile materials, which allows the ink to penetrate evenly in the fiber bulk with its strong capillary wicking force and enhances print resolution. The composite layer of ink and fiber is conductive and enables the antennas to maintain high mechanical flexibility without varying its RF (Radio Frequency) properties. Additionally, the antennas are packaged by laminating porous polyurethane web to make the device durable and washable. The fully packaged antennas maintain the structural flexibility and RF functionality after 15 cycles of washing and drying. To improve the air permeability and enhance flexibility the antenna is also modified by incorporating holes in the both patch and ground layer of the antenna. The antennas were analyzed before and after submerging in water to observe the effect of wetting and drying with respect to frequency response. The porous antenna with holes recovered 3x times faster than the one without holes (solid) from fully wet state (saturated with water) to the dry state, demonstrating its potential use as a moisture sensor system.

  6. Evolutionary Optimization of a Quadrifilar Helical Antenna

    NASA Technical Reports Server (NTRS)

    Lohn, Jason D.; Kraus, William F.; Linden, Derek S.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Automated antenna synthesis via evolutionary design has recently garnered much attention in the research literature. Evolutionary algorithms show promise because, among search algorithms, they are able to effectively search large, unknown design spaces. NASA's Mars Odyssey spacecraft is due to reach final Martian orbit insertion in January, 2002. Onboard the spacecraft is a quadrifilar helical antenna that provides telecommunications in the UHF band with landed assets, such as robotic rovers. Each helix is driven by the same signal which is phase-delayed in 90 deg increments. A small ground plane is provided at the base. It is designed to operate in the frequency band of 400-438 MHz. Based on encouraging previous results in automated antenna design using evolutionary search, we wanted to see whether such techniques could improve upon Mars Odyssey antenna design. Specifically, a co-evolutionary genetic algorithm is applied to optimize the gain and size of the quadrifilar helical antenna. The optimization was performed in-situ in the presence of a neighboring spacecraft structure. On the spacecraft, a large aluminum fuel tank is adjacent to the antenna. Since this fuel tank can dramatically affect the antenna's performance, we leave it to the evolutionary process to see if it can exploit the fuel tank's properties advantageously. Optimizing in the presence of surrounding structures would be quite difficult for human antenna designers, and thus the actual antenna was designed for free space (with a small ground plane). In fact, when flying on the spacecraft, surrounding structures that are moveable (e.g., solar panels) may be moved during the mission in order to improve the antenna's performance.

  7. Land vehicle antennas for satellite mobile communications

    NASA Technical Reports Server (NTRS)

    Haddad, H. A.; Paschen, D.; Pieper, B. V.

    1985-01-01

    Antenna designs applicable to future satellite mobile vehicle communications are examined. Microstrip disk, quadrifilar helix, cylindrical microstrip, and inverted V and U crossed-dipole low gain antennas (3-5 dBic) that provide omnidirectional coverage are described. Diagrams of medium gain antenna (9-12 dBic) concepts are presented; the antennas are classified into three types: (1) electronically steered with digital phase shifters; (2) electronically switched with switchable power divider/combiner; and (3) mechanically steered with motor. The operating characteristics of a conformal antenna with electronic beam steering and a nonconformal design with mechanical steering are evaluated with respect to isolation levels in a multiple satellite system. Vehicle antenna pointing systems and antenna system costs are investigated.

  8. 47 CFR 78.105 - Antenna systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Antenna systems. 78.105 Section 78.105... SERVICE Technical Regulations § 78.105 Antenna systems. (a) For fixed stations operating in the 12.7-13.2... directional antennas that meet the performance standards indicated in the following table. (i) Stations must...

  9. 47 CFR 78.105 - Antenna systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Antenna systems. 78.105 Section 78.105... SERVICE Technical Regulations § 78.105 Antenna systems. (a) For fixed stations operating in the 12.7-13.2... directional antennas that meet the performance standards indicated in the following table. (i) Stations must...

  10. 47 CFR 78.105 - Antenna systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 78.105 Section 78.105... SERVICE Technical Regulations § 78.105 Antenna systems. (a) For fixed stations operating in the 12.7-13.2... directional antennas that meet the performance standards indicated in the following table. (i) Stations must...

  11. 47 CFR 78.105 - Antenna systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Antenna systems. 78.105 Section 78.105... SERVICE Technical Regulations § 78.105 Antenna systems. (a) For fixed stations operating in the 12.7-13.2... directional antennas that meet the performance standards indicated in the following table. (i) Stations must...

  12. A Simple Ultra-Wideband Magneto-Electric Dipole Antenna With High Gain

    NASA Astrophysics Data System (ADS)

    Shuai, Chen-yang; Wang, Guang-ming

    2017-12-01

    A simple ultra-wideband magneto-electric dipole antenna utilizing a differential-fed structure is designed. The antenna mainly comprises three parts, including a novel circular horned reflector, two vertical semicircular shorted patches as a magnetic dipole, and a horizontal U-shaped semicircular electric dipole. A differential feeding structure working as a perfect balun excites the designed antenna. The results of simulation have a good match with the ones of measurement. Results indicate that the designed antenna achieves a wide frequency bandwidth of 107 % which is 3.19 10.61 GHz, when VSWR is below 2. Via introducing the circular horned reflector, the designed antenna attains a steady and high gain of 12±1.5dBi. Moreover, settled broadside direction main beam, high front-to-back ratio, low cross polarization, and the symmetrical and relatively stable radiation patterns in the E-and H-plane are gotten in the impedance bandwidth range. In the practical applications, the proposed antenna that is dc grounded and has a simple structure satisfies the requirement of many outdoor antennas.

  13. Magnetic antenna excitation of whistler modes. IV. Receiving antennas and reciprocity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stenzel, R. L., E-mail: stenzel@physics.ucla.edu; Urrutia, J. M.

    Antenna radiation patterns are an important property of antennas. Reciprocity holds in free space and the radiation patterns for exciting and receiving antennas are the same. In anisotropic plasmas, radiation patterns are complicated by the fact that group and phase velocities differ and certain wave properties like helicity depend on the direction of wave propagation with respect to the background magnetic field B{sub 0}. Interference and wave focusing effects are different than in free space. Reciprocity does not necessarily hold in a magnetized plasma. The present work considers the properties of various magnetic antennas used for receiving whistler modes. Itmore » is based on experimental data from exciting low frequency whistler modes in a large uniform laboratory plasma. By superposition of linear waves from different antennas, the radiation patterns of antenna arrays are derived. Plane waves are generated and used to determine receiving radiation patterns of different receiving antennas. Antenna arrays have radiation patterns with narrow lobes, whose angular position can be varied by physical rotation or electronic phase shifting. Reciprocity applies to broadside antenna arrays but not to end fire arrays which can have asymmetric lobes with respect to B{sub 0}. The effect of a relative motion between an antenna and the plasma has been modeled by the propagation of a short wave packet moving along a linear antenna array. An antenna moving across B{sub 0} has a radiation pattern characterized by an oscillatory “whistler wing.” A receiving antenna in motion can detect any plane wave within the group velocity resonance cone. The radiation pattern also depends on loop size relative to the wavelength. Motional effects prevent reciprocity. The concept of the radiation pattern loses its significance for wave packets since the received signal does not only depend on the antenna but also on the properties of the wave packet. The present results are of

  14. Compact Directional Microwave Antenna for Localized Heating

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W.; Lin, Gregory Y.; Chu, Andrew W.; Dobbins, Justin A.; Arndt, G. Dickey; Ngo, Phong

    2008-01-01

    A directional, catheter-sized cylindrical antenna has been developed for localized delivery of microwave radiation for heating (and thus killing) diseased tissue without excessively heating nearby healthy tissue. By "localized" is meant that the antenna radiates much more in a selected azimuthal direction than in the opposite radial direction, so that it heats tissue much more on one side than it does on the opposite side. This antenna can be inserted using either a catheter or a syringe. A 2.4-mm prototype was tested, although smaller antennas are possible. Prior compact, cylindrical antennas designed for therapeutic localized hyperthermia do not exhibit such directionality; that is, they radiate in approximately axisymmetric patterns. Prior directional antennas designed for the same purpose have been, variously, (1) too large to fit within catheters or (2) too large, after deployment from catheters, to fit within the confines of most human organs. In contrast, the present antenna offers a high degree of directionality and is compact enough to be useable as a catheter in some applications.

  15. SPS antenna pointing control

    NASA Technical Reports Server (NTRS)

    Hung, J. C.

    1980-01-01

    The pointing control of a microwave antenna of the Satellite Power System was investigated emphasizing: (1) the SPS antenna pointing error sensing method; (2) a rigid body pointing control design; and (3) approaches for modeling the flexible body characteristics of the solar collector. Accuracy requirements for the antenna pointing control consist of a mechanical pointing control accuracy of three arc-minutes and an electronic phased array pointing accuracy of three arc-seconds. Results based on the factors considered in current analysis, show that the three arc-minute overall pointing control accuracy can be achieved in practice.

  16. 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.

  17. New Techniques For The Improvement Of The ICRH System ELM Tolerance On JET

    NASA Astrophysics Data System (ADS)

    Monakhov, I.; Blackman, T.; Walden, A.; Nightingale, M.; Whitehurst, A.; Durodie, F.; Jet Efda Contributors

    2003-12-01

    Two complementary improvements to the ELM tolerance of the existing A2 antennas on JET are being assessed. The use of external conjugate-T matching of straps of adjacent antenna arrays could reduce the VSWR levels at RF amplifier output during fast load perturbations. The scheme under consideration uses coaxial line-stretchers (trombones) for tuning the conjugate-T to low resistive impedance (3-6 Ohm) with subsequent stub/trombone circuit impedance transformation to 30 Ohms. Another technique is to modify the RF plant protection system logic to reduce the high VSWR trip duration to an absolute minimum corresponding to a typical ELM response (˜1-2ms) without compromising the plant safety. Both projects are presently being tested and could increase the average power delivered by RF plant into ELMy plasmas at JET.

  18. Investigation of a nanostrip patch antenna in optical frequencies

    NASA Astrophysics Data System (ADS)

    Kashyap, Nitesh; Wani, Zamir Ahmad; Jain, Rishi; Khusboo; Dinesh Kumar, V.

    2014-08-01

    This is the first report and investigation of a patch antenna in optical frequency range. Variety of plasmonic nanoantenna reported so far is good at enhancing the local field intensity of light by orders of magnitude. However, their far-field radiation efficiency is very poor. The proposed patch antenna emits a directional beam with high efficacy in addition to enhancing the intensity of near field. The nano-patch antenna (NPA) consists of a square patch of gold film of dimension 480 nm2, placed on a substrate of dielectric constant \\varepsilon_{{r}} = 3.9 and thickness 150 nm with a ground plane of gold film of dimension 1,080 nm2. The NPA resonates at 210 THz and has gain nearly 2 dB and radiation efficiency 45.18 %. The NPA might be useful in variety of applications such as optical communication, nano-photonics, biosensing, and spectroscopy.

  19. Four-Element Composite Triangular Dielectric Resonator Antenna Using Li2O-1.94MgO-0.02Al2O3-P2O5 Ceramic for Wideband Applications

    NASA Astrophysics Data System (ADS)

    Kumari, Preeti; Tripathi, Pankaj; Sahu, B.; Singh, S. P.; Kumar, Devendra

    2018-05-01

    A simulation and fabrication study of a coaxial probe-fed four-element composite triangular dielectric resonator antenna (TDRA) using low loss Li2O-1.94MgO-0.02Al2O3-P2O5 (LMAP) ceramic and Teflon. LMAP ceramic was carried out and the ceramic was synthesized using a solid-state sintering route. The phase, microstructure and microwave dielectric properties of LMAP were investigated using x-ray diffraction pattern, scanning electron microscopy and a network analyzer. A coaxial probe-fed four-element composite TDRA was designed and fabricated using LMAP as one section of each composite element of the proposed antenna. Each triangular element of the proposed dielectric resonator antenna (DRA) consists of two sections of different dielectric constant materials. The inner triangular section touching the coaxial probe at one of its corners is made of the LMAP ceramic (ɛ r = 6.2) while othe uter section is made of Teflon (ɛ r = 2.1). Four triangular DRA elements are excited bya centrally located 50-Ω coaxial probe. The parametric study of the proposed antenna was performed through simulation using Ansys High Frequency Structure Simulator software by varying the dimensions and dielectric constants of both sections of each triangular element of the TDRA to optimize the results for obtaining a wideband antenna. The simulated resonant frequency of 9.30 GHz with a percentage bandwidth of 61.65% for the proposed antenna is obtained within its operating frequency range of 7.82-14.8 GHz. Monopole-like radiation patterns with low cross-polarization levels and a peak gain of 5.63 dB are obtained for the proposed antenna through simulation. The antenna prototype having optimized dimensions has also been fabricated. The experimental resonant frequency of 9.10 GHz with a percentage bandwidth of 66.09% is obtained within its operating frequency range of 7.70-15.30 GHz. It is found that the simulation results for the proposed antenna are in close agreement with the measured data. The

  20. A dual frequency microstrip antenna for Ka band

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.; Baddour, M. F.

    1985-01-01

    For fixed satellite communication systems at Ka band with downlink at 17.7 to 20.2 GHz and uplink at 27.5 to 30.0 GHz, the focused optics and the unfocused optics configurations with monolithic phased array feeds have often been used to provide multiple fixed and multiple scanning spot beam coverages. It appears that a dual frequency microstrip antenna capable of transmitting and receiving simultaneously is highly desirable as an array feed element. This paper describes some early efforts on the development and experimental testing of a dual frequency annular microstrip antenna. The antenna has potential application for use in conjunction with a monolithic microwave integrated circuit device as an active radiating element in a phased array of phased array feeds. The antenna is designed to resonate at TM sub 12 and TM sub 13 modes and tuned with a circumferential microstrip ring to vary the frequency ratio. Radiation characteristics at both the high and low frequencies are examined. Experimental results including radiating patterns and swept frequency measurements are presented.

  1. International Conference on Antennas and Propagation (ICAP 89), 6th, University of Warwick, Coventry, England, Apr. 4-7, 1989, Proceedings. Part 1 - Antennas. Part 2 - Propagation

    NASA Astrophysics Data System (ADS)

    Various papers on antennas and propagation are presented. The general topics addressed include: phased arrays; reflector antennas; slant path propagation; propagation data for HF radio systems performance; satellite and earth station antennas; radio propagation in the troposphere; propagation data for HF radio systems performance; microstrip antennas; rain radio meteorology; conformal antennas; horns and feed antennas; low elevation slant path propagation; radio millimeter wave propagation; array antennas; propagation effects on satellite mobile, satellite broadcast, and aeronautical systems; ionospheric irregularities and motions; adaptive antennas; transient response; measurement techniques; clear air radio meteorology; ionospheric and propagation modeling; millimeter wave and lens antennas; electromagnetic theory and numerical techniques; VHF propagation modeling, system planning methods; radio propagation theoretical techniques; scattering and diffraction; transhorizon rain scatter effects; ELF-VHF and broadcast antennas; clear air millimeter propagation; scattering and frequency-selective surfaces; antenna technology; clear air transhorizon propagation.

  2. 47 CFR 22.365 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Antenna structures; air navigation safety. 22... Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a hazard to air navigation. In general, antenna structure owners are...

  3. 47 CFR 22.365 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Antenna structures; air navigation safety. 22... Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a hazard to air navigation. In general, antenna structure owners are...

  4. 47 CFR 22.365 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Antenna structures; air navigation safety. 22... Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a hazard to air navigation. In general, antenna structure owners are...

  5. 47 CFR 22.365 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Antenna structures; air navigation safety. 22... Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a hazard to air navigation. In general, antenna structure owners are...

  6. 47 CFR 22.365 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Antenna structures; air navigation safety. 22... Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a hazard to air navigation. In general, antenna structure owners are...

  7. Spiral Antenna-Coupled Microbridge Structures for THz Application.

    PubMed

    Gou, Jun; Zhang, Tian; Wang, Jun; Jiang, Yadong

    2017-12-01

    Bolometer sensor is a good candidate for THz imaging due to its compact system, low cost, and wideband operation. Based on infrared microbolometer structures, two kinds of antenna-coupled microbridge structures are proposed with different spiral antennas: spiral antenna on support layer and spiral antenna with extended legs. Aiming at applications in detection and imaging, simulations are carried out mainly for optimized absorption at 2.52 THz, which is the radiation frequency of far-infrared CO 2 lasers. The effects of rotation angle, line width, and spacing of the spiral antenna on THz wave absorption of microbridge structures are discussed. Spiral antenna, with extended legs, is a good solution for high absorption rate at low absorption frequency and can be used as electrode lead simultaneously for simplified manufacturing process. A spiral antenna-coupled microbridge structure with an absorption rate of more than 75% at 2.52 THz is achieved by optimizing the structure parameters. This research demonstrates the use of different spiral antennas for enhanced and tunable THz absorption of microbridge structures and provides an effective way to fabricate THz microbolometer detectors with great potential in the application of real-time THz imaging.

  8. L-Band Orthogonal-Mode Crossed-Slot Antenna and VHF Crossed-Loop Antenna

    DOT National Transportation Integrated Search

    1972-01-01

    A low-gain, circularly polarized, L-ban antenna; a low-gain, lineraly polarized, L-band antenna; and a low-gain, lineraly polarized, L-ban antenna; and a low-gain, circularly polarized, upper hemisphere, VHF satellite communications antenna intended ...

  9. Equipment: Antenna systems

    NASA Astrophysics Data System (ADS)

    Petrie, L. E.

    1983-05-01

    Some antenna fundamentals as well as definitions of the principal terms used in antenna engineering are described. Methods are presented for determining the desired antenna radiation patterns for an HF communication circuit or service area. Sources for obtaining or computing radiation pattern information are outlined. Comparisons are presented between the measured and computed radiation patterns. The effect of the properties of the ground on the antenna gain and pattern are illustrated for several types of antennas. Numerous examples are given of the radiation patterns for typical antennas used on short, intermediate and long distance circuits or both mobile and fixed service operations. The application of adaptive antenna arrays and active antennas in modern HF communication systems are briefly reviewed.

  10. Equipment: Antenna systems

    NASA Astrophysics Data System (ADS)

    Petrie, L. E.

    1986-03-01

    Some antenna fundamentals as well as definitions of the principal terms used in antenna engineering are described. Methods are presented for determining the desired antenna radiation patterns for HF communication circuit or service area. Sources for obtaining or computing radiation pattern information are outlined. Comparisons are presented between the measured and computed radiation patterns. The effect of the properties of the ground on the antenna gain and the pattern are illustrated for several types of antennas. Numerous examples are given of the radiation patterns for typical antennas used on short, intermediate and long distance circuits for both mobile and fixed service operations. The application of adaptive antenna arrays and active antennas in modern HF communication systems are briefly reviewed.

  11. 47 CFR 22.1011 - Antenna height limitations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Antenna height limitations. 22.1011 Section 22... MOBILE SERVICES Offshore Radiotelephone Service § 22.1011 Antenna height limitations. The antenna height of offshore stations must not exceed 61 meters (200 feet) above mean sea level. The antenna height of...

  12. 47 CFR 22.1011 - Antenna height limitations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Antenna height limitations. 22.1011 Section 22... MOBILE SERVICES Offshore Radiotelephone Service § 22.1011 Antenna height limitations. The antenna height of offshore stations must not exceed 61 meters (200 feet) above mean sea level. The antenna height of...

  13. 47 CFR 22.1011 - Antenna height limitations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Antenna height limitations. 22.1011 Section 22... MOBILE SERVICES Offshore Radiotelephone Service § 22.1011 Antenna height limitations. The antenna height of offshore stations must not exceed 61 meters (200 feet) above mean sea level. The antenna height of...

  14. 47 CFR 22.1011 - Antenna height limitations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Antenna height limitations. 22.1011 Section 22... MOBILE SERVICES Offshore Radiotelephone Service § 22.1011 Antenna height limitations. The antenna height of offshore stations must not exceed 61 meters (200 feet) above mean sea level. The antenna height of...

  15. 47 CFR 22.1011 - Antenna height limitations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Antenna height limitations. 22.1011 Section 22... MOBILE SERVICES Offshore Radiotelephone Service § 22.1011 Antenna height limitations. The antenna height of offshore stations must not exceed 61 meters (200 feet) above mean sea level. The antenna height of...

  16. 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

  17. Three-dimensional effects for radio frequency antenna modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    1994-10-15

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

  18. Three-dimensional effects for radio frequency antenna modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    1993-12-31

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

  19. A novel antenna for ultra-wide-band applications

    NASA Technical Reports Server (NTRS)

    Lai, Albert K. Y.; Sinopoli, Albert L.; Burnside, Walter D.

    1992-01-01

    An ultrawideband antenna based on a slotline feed structure, a bowtie horn, and a rolled edge termination was developed, analyzed, and measured. Empirical data showed that its beamwidths and bandwidth are dependent on its physical dimensions which are easily controllable by an antenna designer. Measured patterns of models with various radiation properties are shown to substantiate these design rules. A flat plateau-like main beam, low voltage standing-wave ratio (VSWR), the ability to produce both wide (60 deg) and narrow (30 deg) half-power beamwidths, low sidelobes and backlobe (40-50 dB down), low cross-polarized levels (20-25 dB down), and independent control of E- and H-plane beamwidths over an ultrawide bandwidth, say 2-18 GHz, are some of the strong points of this antenna type.

  20. SAR reduction using a single SRR superstrate for a dual-band antenna.

    PubMed

    Rosaline, Imaculate; Singaravelu, Raghavan

    2017-01-01

    A dual-band microstrip antenna operating at GSM 900 and GSM 1800 MHz is designed initially. Then a single split ring resonator (SRR) structure is used as a superstrate for this dual-band antenna. A circular current is induced in the SRR due to the perpendicular plane wave excitation, which in turn leads to an electric excitation coupled to the magnetic resonance. It also exhibits higher order excitations at 0.9 and 1.8 GHz which ultimately resulted in specific absorption rate (SAR) reduction of human head at both the designed frequencies of the antenna. The antenna and the SRR superstrate are printed on a 1.6 mm thick FR-4 substrate of dimension 59.6 × 49.6 mm 2 . Analysis of the SRR using the classic waveguide theory approach is discussed. Radiation pattern of the antenna in the presence of SRR superstrate and human head is also discussed. Prototype of the antenna along with the SRR superstrate is fabricated and measured for return loss and radiation pattern. Measurement results fairly agree with the simulated results. A human head phantom is utilized in the calculation of SAR.

  1. A compact planar multi-broad band monopole antenna for mobile devices

    NASA Astrophysics Data System (ADS)

    Zhong, Xiaoqing; Yao, Bin; Zheng, Qinhong; Yang, Jikong; Cao, Xiangqi

    2015-10-01

    A Multiple-frequency broadband planar monopole antenna is proposed in this Paper. The antenna is stimulated and numerically optimized by HFSS13.0 (High Frequency Structure Simulator). The size of it is 39mm×22mm×1.7mm. The antenna resonates at many frequencies. The parameter S11<=-6dB means the proposed antenna matches well with its feed-line and covers many useful operation frequency bands, including 2G(DCS1800 and PCS1900), 3G(UMTS), 4G(LTE2300 and LTE2500), ISM, WLAN. It is quiet appropriate for the present ultra-thin smart phones

  2. Radiation pattern of a borehole radar antenna

    USGS Publications Warehouse

    Ellefsen, K.J.; Wright, D.L.

    2005-01-01

    The finite-difference time-domain method was used to simulate radar waves that were generated by a transmitting antenna inside a borehole. The simulations were of four different models that included features such as a water-filled borehole and an antenna with resistive loading. For each model, radiation patterns for the far-field region were calculated. The radiation patterns show that the amplitude of the radar wave was strongly affected by its frequency, the water-filled borehole, the resistive loading of the antenna, and the external metal parts of the antenna (e.g., the cable head and the battery pack). For the models with a water-filled borehole, their normalized radiation patterns were practically identical to the normalized radiation pattern of a finite-length electric dipole when the wavelength in the formation was significantly greater than the total length of the radiating elements of the model antenna. The minimum wavelength at which this criterion was satisfied depended upon the features of the antenna, especially its external metal parts. ?? 2005 Society of Exploration Geophysicists. All rights reserved.

  3. Fundamental Fractal Antenna Design Process

    NASA Astrophysics Data System (ADS)

    Zhu, L. P.; Kim, T. C.; Kakas, G. D.

    2017-12-01

    Antenna designers are always looking to come up with new ideas to push the envelope for new antennas, using a smaller volume while striving for higher bandwidth, wider bandwidth, and antenna gain. One proposed method of increasing bandwidth or shrinking antenna size is via the use of fractal geometry, which gives rise to fractal antennas. Fractals are those fun shapes that if one zooms in or zoom out, the structure is always the same. Design a new type of antenna based on fractal antenna design by utilize the Design of Experiment (DOE) will be shown in fractal antenna design process. Investigate conformal fractal antenna design for patterns, dimensions, and size, of the antenna but maintaining or improving the antenna performance. Research shows an antenna designer how to create basic requirements of the fractal antenna through a step by step process, and provides how to optimize the antenna design with the model prediction, lab measurement, and actual results from the compact range measurement on the antenna patterns.

  4. 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.

  5. Proceedings of the Antenna Applications Symposium Held in Hanscom AFB, Massachusetts on 23-25 September 1987. Volume 2

    DTIC Science & Technology

    1988-07-01

    iv BROADBAND ANTENNAS Contents 21. "Performance Characteristics of Notch Array Elements Over a 6/1 263 Frequoncy Band," C. J. Monser * 22. " Broadband ...synthesized RF signal is taken from the output port of the Hewlett-Packard 8408B Microvae Network Alnalyzer to a 20-watt TWT anplifier, and then to...j kr -Sinn H 0 = -jk 47rjk ° a 2 H r4 0 r 406 4. Helix antenna The cur-ent distribution of a helix antenna as shown in Fig. 2.11 of [33 may be

  6. Radiation pattern of a borehole radar antenna

    USGS Publications Warehouse

    Ellefsen, K.J.; Wright, D.L.

    2002-01-01

    To understand better how a borehole antenna radiates radar waves into a formation, this phenomenon is simulated numerically using the finite-difference, time-domain method. The simulations are of two different antenna models that include features like a driving point fed by a coaxial cable, resistive loading of the antenna, and a water-filled borehole. For each model, traces are calculated in the far-field region, and then, from these traces, radiation patterns are calculated. The radiation patterns show that the amplitude of the radar wave is strongly affected by its frequency, its propagation direction, and the resistive loading of the antenna.

  7. Analysis of a Waveguide-Fed Metasurface Antenna

    NASA Astrophysics Data System (ADS)

    Smith, David R.; Yurduseven, Okan; Mancera, Laura Pulido; Bowen, Patrick; Kundtz, Nathan B.

    2017-11-01

    The metasurface concept has emerged as an advantageous reconfigurable antenna architecture for beam forming and wave-front shaping, with applications that include satellite and terrestrial communications, radar, imaging, and wireless power transfer. The metasurface antenna consists of an array of metamaterial elements distributed over an electrically large structure, each subwavelength in dimension and with subwavelength separation between elements. In the antenna configuration we consider, the metasurface is excited by the fields from an attached waveguide. Each metamaterial element can be modeled as a polarizable dipole that couples the waveguide mode to radiation modes. Distinct from the phased array and electronically-scanned-antenna architectures, a dynamic metasurface antenna does not require active phase shifters and amplifiers but rather achieves reconfigurability by shifting the resonance frequency of each individual metamaterial element. We derive the basic properties of a one-dimensional waveguide-fed metasurface antenna in the approximation in which the metamaterial elements do not perturb the waveguide mode and are noninteracting. We derive analytical approximations for the array factors of the one-dimensional antenna, including the effective polarizabilities needed for amplitude-only, phase-only, and binary constraints. Using full-wave numerical simulations, we confirm the analysis, modeling waveguides with slots or complementary metamaterial elements patterned into one of the surfaces.

  8. Antenna theory: Analysis and design

    NASA Astrophysics Data System (ADS)

    Balanis, C. A.

    The book's main objective is to introduce the fundamental principles of antenna theory and to apply them to the analysis, design, and measurements of antennas. In a description of antennas, the radiation mechanism is discussed along with the current distribution on a thin wire. Fundamental parameters of antennas are examined, taking into account the radiation pattern, radiation power density, radiation intensity, directivity, numerical techniques, gain, antenna efficiency, half-power beamwidth, beam efficiency, bandwidth, polarization, input impedance, and antenna temperature. Attention is given to radiation integrals and auxiliary potential functions, linear wire antennas, loop antennas, linear and circular arrays, self- and mutual impedances of linear elements and arrays, broadband dipoles and matching techniques, traveling wave and broadband antennas, frequency independent antennas and antenna miniaturization, the geometrical theory of diffraction, horns, reflectors and lens antennas, antenna synthesis and continuous sources, and antenna measurements.

  9. Aligning a Receiving Antenna Array to Reduce Interference

    NASA Technical Reports Server (NTRS)

    Jongeling, Andre P.; Rogstad, David H.

    2009-01-01

    A digital signal-processing algorithm has been devised as a means of aligning (as defined below) the outputs of multiple receiving radio antennas in a large array for the purpose of receiving a desired weak signal transmitted by a single distant source in the presence of an interfering signal that (1) originates at another source lying within the antenna beam and (2) occupies a frequency band significantly wider than that of the desired signal. In the original intended application of the algorithm, the desired weak signal is a spacecraft telemetry signal, the antennas are spacecraft-tracking antennas in NASA s Deep Space Network, and the source of the wide-band interfering signal is typically a radio galaxy or a planet that lies along or near the line of sight to the spacecraft. The algorithm could also afford the ability to discriminate between desired narrow-band and nearby undesired wide-band sources in related applications that include satellite and terrestrial radio communications and radio astronomy. The development of the present algorithm involved modification of a prior algorithm called SUMPLE and a predecessor called SIMPLE. SUMPLE was described in Algorithm for Aligning an Array of Receiving Radio Antennas (NPO-40574), NASA Tech Briefs Vol. 30, No. 4 (April 2006), page 54. To recapitulate: As used here, aligning signifies adjusting the delays and phases of the outputs from the various antennas so that their relatively weak replicas of the desired signal can be added coherently to increase the signal-to-noise ratio (SNR) for improved reception, as though one had a single larger antenna. Prior to the development of SUMPLE, it was common practice to effect alignment by means of a process that involves correlation of signals in pairs. SIMPLE is an example of an algorithm that effects such a process. SUMPLE also involves correlations, but the correlations are not performed in pairs. Instead, in a partly iterative process, each signal is appropriately weighted

  10. DSN 70-meter antenna X-band gain, phase, and pointing performance, with particular application for Voyager 2 Neptune encounter

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    The gain, phase, and pointing performance of the Deep Space Network (DSN) 70 m antennas are investigated using theoretical antenna analysis computer programs that consider the gravity induced deformation of the antenna surface and quadripod structure. The microwave effects are calculated for normal subreflector focusing motion and for special fixed-subreflector conditions that may be used during the Voyager 2 Neptune encounter. The frequency stability effects of stepwise lateral and axial subreflector motions are also described. Comparisons with recently measured antenna efficiency and subreflector motion tests are presented. A modification to the existing 70 m antenna pointing squint correction constant is proposed.

  11. 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.

  12. Two antenna, two pass interferometric synthetic aperture radar

    DOEpatents

    Martinez, Ana; Doerry, Armin W.; Bickel, Douglas L.

    2005-06-28

    A multi-antenna, multi-pass IFSAR mode utilizing data driven alignment of multiple independent passes can combine the scaling accuracy of a two-antenna, one-pass IFSAR mode with the height-noise performance of a one-antenna, two-pass IFSAR mode. A two-antenna, two-pass IFSAR mode can accurately estimate the larger antenna baseline from the data itself and reduce height-noise, allowing for more accurate information about target ground position locations and heights. The two-antenna, two-pass IFSAR mode can use coarser IFSAR data to estimate the larger antenna baseline. Multi-pass IFSAR can be extended to more than two (2) passes, thereby allowing true three-dimensional radar imaging from stand-off aircraft and satellite platforms.

  13. Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Nagayama, Y.; Ito, N.; Kuwahara, D.; Tsuchiya, H.; Yamaguchi, S.

    2017-04-01

    The two-dimensional (2-D) Horn-antenna Millimeter-wave Imaging Device (HMID) has been developed for the O-mode Microwave Imaging Reflectometry (O-MIR) in the Large Helical Device (LHD). The detectable frequency range of the HMID is 23-33 GHz, which corresponds to the cutoff electron density of 0.8-1.5 × 1019 m-3 in the O-MIR. The HMID is a 2-D imaging device that improves on the horn-antenna mixer array, which had been developed for the X-mode MIR in the LHD. In the HMID, the signal (RF) wave from the horn antenna is transmitted to the microstrip line by the finline transmitter, and this is mixed by the double-balanced-mixer with the local oscillation wave that is fed by a coaxial cable. By using the HMID, the MIR optical system can be significantly simplified.

  14. Proceedings of the 2007 Antenna Applications Symposium. Volume 2

    DTIC Science & Technology

    2007-12-20

    field strength at 1 km [1]. It is based on an ideal short monopole, with 1 kW available power and no earth losses. Losses from the ideal monopole are...antenna operates over UHF and L Bands, providing ground- based transmit/receive capability for next generation radios. Filters are integrated into...enclosed in a housing which also serves as the base of the antenna (see Figure 6). The filters achieve approximately 40 dB (UHF low-pass) and 50 dB

  15. A Dielectric Rod Antenna for Picosecond Pulse Stimulation of Neurological Tissue

    PubMed Central

    Petrella, Ross A.; Schoenbach, Karl H.; Xiao, Shu

    2016-01-01

    A dielectrically loaded wideband rod antenna has been studied as a pulse delivery system to subcutaneous tissues. Simulation results applying 100 ps electrical pulse show that it allows us to generate critical electric field for biological effects, such as brain stimulation, in the range of several centimeters. In order to reach the critical electric field for biological effects, which is approximately 20 kV/cm, at a depth of 2 cm, the input voltage needs to be 175 kV. The electric field spot size in the brain at this position is approximately 1 cm2. Experimental studies in free space with a conical antenna (part of the antenna system) with aluminum nitride as the dielectric have confirmed the accuracy of the simulation. These results set the foundation for high voltage in situ experiments on the complete antenna system and the delivery of pulses to biological tissue. PMID:27563160

  16. Three-dimensional effects for radio frequency antenna modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    1993-09-01

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

  17. Meandered-line antenna with integrated high-impedance surface.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Forman, Michael A.

    2010-09-01

    A reduced-volume antenna composed of a meandered-line dipole antenna over a finite-width, high-impedance surface is presented. The structure is novel in that the high-impedance surface is implemented with four Sievenpiper via-mushroom unit cells, whose area is optimized to match the meandered-line dipole antenna. The result is an antenna similar in performance to patch antenna but one fourth the area that can be deployed directly on the surface of a conductor. Simulations demonstrate a 3.5 cm ({lambda}/4) square antenna with a bandwidth of 4% and a gain of 4.8 dBi at 2.5 GHz.

  18. Reconfigurable antenna using plasma reflector

    NASA Astrophysics Data System (ADS)

    Jusoh, Mohd Taufik; Ahmad, Khairol Amali; Din, Muhammad Faiz Md; Hashim, Fakroul Ridzuan

    2018-02-01

    This paper presents the feasibility study and design of plasma implementation in industrial, scientific and medical (ISM) communication band. A reflector antenna with rounded shaped is proposed to collimate beam in particular direction radiated by a quarter wave antenna operating at 2.4GHz. The simulations result has shown that by using plasma as the reflector elements, the gain, directivity and radiation patterns are identical with metal elements with only small different in the broadside direction. The versatility of the antenna is achievable by introducing electrical reconfigurable option to change the beam pattern.

  19. Antenna and Electronics Cost Tradeoffs For Large Arrays

    NASA Technical Reports Server (NTRS)

    D'Addario, Larry R.

    2007-01-01

    This viewgraph presentation describes the cost tradeoffs for large antenna arrays. The contents include: 1) Cost modeling for large arrays; 2) Antenna mechanical cost over a wide range of sizes; and 3) Cost of per-antenna electronics.

  20. Frequency Reconfigurable Quasi-Yagi Antenna with a Novel Balun Loading Four PIN Diodes

    NASA Astrophysics Data System (ADS)

    Xie, Peng; Wang, Guang-Ming; Li, Hai-Peng; Wen, Tong; Kong, Xiangxin

    2018-04-01

    A novel frequency reconfigurable Quasi-Yagi antenna is proposed. The antenna has two dipoles on different layers of the substrate and they are fed by two coplanar striplines. Four PIN diodes, loading inside the coplanar striplines, are used as the switches. By switching the states of the four diodes, the antenna can work in three modes with different working bands around 3.5 GHz (cover the band of WiMAX), 5.2 GHz (cover the band of WLAN) and 7 GHz respectively. In addition, the working bands can be independently tuned by adjusting several parameters of the antenna. A prototype antenna was fabricated and tested. Good agreement between the simulation and the measurement is achieved. The results prove that the antenna can realize frequency reconfiguration effectively while maintaining the pattern characteristic of Yagi antenna at all frequency.

  1. Modified Minkowski Fractal Antenna for Wireless Applications

    NASA Astrophysics Data System (ADS)

    Brar, Amandeep Singh; Sivia, Jagtar Singh

    2018-06-01

    A multiband Modified Minkowski Fractal Antenna which can operate at UHF, L, S, C and X band of IEEE standard is presented in this paper. The proposed antenna is simple and low cost. It can work on many bands starting from few hundred megahertz (500 MHz) frequency up to gigahertz (7.1 GHz) frequency. Structure of antenna has been designed by combining Minkowski curve with its inverted Minkowski curve. A maximum gain up to 20 dB, VSWR, radiation pattern and twenty resonant frequencies has been achieved using proposed antenna structure. Simulated results executed in HFSS software. Proposed antenna works on resonant frequencies of 496 MHz to 1.06 GHz (wide band), 1.45, 2.09, 2.38, 3.23, 3.79, 4.06, 4.35, 4.65, 4.82, 5.24, 5.62, 6.12 GHz etc.

  2. 47 CFR 24.55 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Antenna structures; air navigation safety. 24... SERVICES PERSONAL COMMUNICATIONS SERVICES Technical Standards § 24.55 Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a...

  3. 47 CFR 24.55 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Antenna structures; air navigation safety. 24... SERVICES PERSONAL COMMUNICATIONS SERVICES Technical Standards § 24.55 Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a...

  4. 47 CFR 24.55 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Antenna structures; air navigation safety. 24... SERVICES PERSONAL COMMUNICATIONS SERVICES Technical Standards § 24.55 Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a...

  5. 47 CFR 24.55 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Antenna structures; air navigation safety. 24... SERVICES PERSONAL COMMUNICATIONS SERVICES Technical Standards § 24.55 Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a...

  6. 47 CFR 24.55 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Antenna structures; air navigation safety. 24... SERVICES PERSONAL COMMUNICATIONS SERVICES Technical Standards § 24.55 Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a...

  7. Spacecraft Antennas

    NASA Technical Reports Server (NTRS)

    Jamnejad, Vahraz; Manshadi, Farzin; Rahmat-Samii, Yahya; Cramer, Paul

    1990-01-01

    Some of the various categories of issues that must be considered in the selection and design of spacecraft antennas for a Personal Access Satellite System (PASS) are addressed, and parametric studies for some of the antenna concepts to help the system designer in making the most appropriate antenna choice with regards to weight, size, and complexity, etc. are provided. The question of appropriate polarization for the spacecraft as well as for the User Terminal Antenna required particular attention and was studied in some depth. Circular polarization seems to be the favored outcome of this study. Another problem that has generally been a complicating factor in designing the multiple beam reflector antennas, is the type of feeds (single vs. multiple element and overlapping vs. non-overlapping clusters) needed for generating the beams. This choice is dependent on certain system design factors, such as the required frequency reuse, acceptable interbeam isolation, antenna efficiency, number of beams scanned, and beam-forming network (BFN) complexity. This issue is partially addressed, but is not completely resolved. Indications are that it may be possible to use relatively simple non-overlapping clusters of only a few elements, unless a large frequency reuse and very stringent isolation levels are required.

  8. Taiwanese antennas for the Sub-Millimeter Array: a progress report

    NASA Astrophysics Data System (ADS)

    Raffin, Phillippe A.; Liu, Ching-Tang; Cervera, Mathieu; Chang, Chi-Ling; Chen, Ming-Tang; Lee, Cheng-Ching; Lee, Typhoon; Lo, Kwok-Yung; Ma, Rwei-Ping; Martin, Robert N.; Martin-Cocher, Pierre; Ong, Ching-Long; Park, Yong-Sun; Tsai, Rong-Den; Wu, Enboa; Yang, Shun-Cheng; Yang, Tien-Szu

    2000-07-01

    The Academia Sinica, Institute for Astronomy and Astrophysics (ASIAA) is building two antennas to be added to the six antennas of the Sub-Millimeter Array (SMA) of the Smithsonian Astrophysical Observatory (SAO). The antennas have been designed at SAO and are currently under construction at Mauna Kea. ASIAA's two antennas are made in Taiwan from parts manufactured locally and imported from Europe and from the USA. This report will focus on the manufacturing and testing of 2 major components: the alidade and the reflector. We will emphasize the work done on the composite parts used in the 6- meter reflectors, namely the carbon fiber tubes for the backup structure, the carbon fiber legs of the quadrupod and the composite central hub. We will discuss the modal testing and pointing tests of the antennas. Finally this report will show how the Taiwanese industry was able to respond to the high manufacturing standards required to build sub-millimeter antennas. The design and manufacturing capabilities of the Aeronautical Research Laboratories and China Shipbuilding Corporation have made possible the construction of the telescopes in Taiwan.

  9. Antenna Controller Replacement Software

    NASA Technical Reports Server (NTRS)

    Chao, Roger Y.; Morgan, Scott C.; Strain, Martha M.; Rockwell, Stephen T.; Shimizu, Kenneth J.; Tehrani, Barzia J.; Kwok, Jaclyn H.; Tuazon-Wong, Michelle; Valtier, Henry; Nalbandi, Reza; hide

    2010-01-01

    The Antenna Controller Replacement (ACR) software accurately points and monitors the Deep Space Network (DSN) 70-m and 34-m high-efficiency (HEF) ground-based antennas that are used to track primarily spacecraft and, periodically, celestial targets. To track a spacecraft, or other targets, the antenna must be accurately pointed at the spacecraft, which can be very far away with very weak signals. ACR s conical scanning capability collects the signal in a circular pattern around the target, calculates the location of the strongest signal, and adjusts the antenna pointing to point directly at the spacecraft. A real-time, closed-loop servo control algorithm performed every 0.02 second allows accurate positioning of the antenna in order to track these distant spacecraft. Additionally, this advanced servo control algorithm provides better antenna pointing performance in windy conditions. The ACR software provides high-level commands that provide a very easy user interface for the DSN operator. The operator only needs to enter two commands to start the antenna and subreflector, and Master Equatorial tracking. The most accurate antenna pointing is accomplished by aligning the antenna to the Master Equatorial, which because of its small size and sheltered location, has the most stable pointing. The antenna has hundreds of digital and analog monitor points. The ACR software provides compact displays to summarize the status of the antenna, subreflector, and the Master Equatorial. The ACR software has two major functions. First, it performs all of the steps required to accurately point the antenna (and subreflector and Master Equatorial) at the spacecraft (or celestial target). This involves controlling the antenna/ subreflector/Master-Equatorial hardware, initiating and monitoring the correct sequence of operations, calculating the position of the spacecraft relative to the antenna, executing the real-time servo control algorithm to maintain the correct position, and

  10. Thermal Analysis of Antenna Structures. Part 2: Panel Temperature Distribution

    NASA Technical Reports Server (NTRS)

    Schonfeld, D.; Lansing, F. L.

    1983-01-01

    This article is the second in a series that analyzes the temperature distribution in microwave antennas. An analytical solution in a series form is obtained for the temperature distribution in a flat plate analogous to an antenna surface panel under arbitrary temperature and boundary conditions. The solution includes the effects of radiation and air convection from the plate. Good agreement is obtained between the numerical and analytical solutions.

  11. A Double-Negative Metamaterial-Inspired Mobile Wireless Antenna for Electromagnetic Absorption Reduction

    PubMed Central

    Alam, Touhidul; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

    2015-01-01

    A double-negative metamaterial-inspired antenna is presented for mobile wireless applications. The antenna consists of a semi-circular radiating patch and a 3 × 4 hexagonal shaped metamaterial unit cell array in the ground plane. The antenna is fed with a 50 Ω microstrip feed line. The electric dimensions of the proposed antenna are 0.20λ × 0.26λ × 0.004λ, at the low-end frequency. The proposed antenna achieves a −10 dB impedance with a bandwidth of 2.29 GHz at the lower band and 1.28 GHz at the upper band and can operate for most of the mobile applications such as upper GSM bands, WiMAX, Bluetooth, and wireless local area network (WLAN) frequency bands. The focused novelties of the proposed antenna are its small size, multi-standard operating bands, and electromagnetic absorption reduction at all the operating frequencies using the double-negative metamaterial ground plane. PMID:28793474

  12. A Double-Negative Metamaterial-Inspired Mobile Wireless Antenna for Electromagnetic Absorption Reduction.

    PubMed

    Alam, Touhidul; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

    2015-07-29

    A double-negative metamaterial-inspired antenna is presented for mobile wireless applications. The antenna consists of a semi-circular radiating patch and a 3 × 4 hexagonal shaped metamaterial unit cell array in the ground plane. The antenna is fed with a 50 Ω microstrip feed line. The electric dimensions of the proposed antenna are 0.20λ × 0.26λ × 0.004λ, at the low-end frequency. The proposed antenna achieves a -10 dB impedance with a bandwidth of 2.29 GHz at the lower band and 1.28 GHz at the upper band and can operate for most of the mobile applications such as upper GSM bands, WiMAX, Bluetooth, and wireless local area network (WLAN) frequency bands. The focused novelties of the proposed antenna are its small size, multi-standard operating bands, and electromagnetic absorption reduction at all the operating frequencies using the double-negative metamaterial ground plane.

  13. 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.

  14. Deployable antenna

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W. (Inventor); Dobbins, Justin A. (Inventor); Lin, Greg Y. (Inventor); Chu, Andrew W. (Inventor); Scully, Robert C. (Inventor)

    2006-01-01

    A deployable antenna and method for using wherein the deployable antenna comprises a collapsible membrane having at least one radiating element for transmitting electromagnetic waves, receiving electromagnetic waves, or both.

  15. RF Sheath-Enhanced Plasma Surface Interaction Studies using Beryllium Optical Emission Spectroscopy in JET ITER-Like Wall

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Agarici, G.; Klepper, C Christopher; Colas, L.

    A dedicated study on JET-ILW, deploying two types of ICRH antennas and spectroscopic observation spots at two outboard, beryllium limiters, has provided insight on long-range (up to 6m) RFenhanced plasma-surface interactions (RF-PSI) due to near-antenna electric fields. To aid in the interpretation of optical emission measurements of these effects, the antenna near-fields are computed using the TOPICA code, specifically run for the ITER-like antenna (ILA); similar modelling already existed for the standard JET antennas (A2). In the experiment, both antennas were operated in current drive mode, as RF-PSI tends to be higher in this phasing and at similar power (∼0.5more » MW). When sweeping the edge magnetic field pitch angle, peaked RF-PSI effects, in the form of 2-4 fold increase in the local Be source,are consistently measured with the observation spots magnetically connect to regions of TOPICAL-calculated high near-fields, particularly at the near-antenna limiters. It is also found that similar RF-PSI effects are produced by the two types of antenna on similarly distant limiters. Although this mapping of calculated near-fields to enhanced RF-PSI gives only qualitative interpretion of the data, the present dataset is expected to provide a sound experimental basis for emerging RF sheath simulation model validation.« less

  16. The 60 GHz antenna system analyses for intersatellite links, phase A

    NASA Technical Reports Server (NTRS)

    1984-01-01

    A tradeoff study for 60 GHz antenna systems applicable to an advanced Tracking and Data Acquisition System is also discussed. A conceptual design of a preferred antenna system is also discussed. The tradeoff results for four types of antenna systems are presented: (1) Reflector/fixed feed, (2) Mechanical scan, (3) Electronic scan; and (4) Hybrid mechanical/electronic scan. The 12 candidate antennas were assessed on the basis of a preliminary design and a performance analysis then were scored against 15 weighted parameters. This process resulted in the ranking of the 12 candidates for the two applications, namely, for the geostationary TDAS only with a narrow field of view and for low orbit user satellites with a wide field of view.

  17. 47 CFR 27.56 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Antenna structures; air navigation safety. 27... SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.56 Antenna structures; air navigation safety. A licensee that owns its antenna structure(s) must not allow such antenna structure(s) to...

  18. 47 CFR 27.56 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Antenna structures; air navigation safety. 27... SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.56 Antenna structures; air navigation safety. A licensee that owns its antenna structure(s) must not allow such antenna structure(s) to...

  19. 47 CFR 27.56 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Antenna structures; air navigation safety. 27... SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.56 Antenna structures; air navigation safety. A licensee that owns its antenna structure(s) must not allow such antenna structure(s) to...

  20. 47 CFR 27.56 - Antenna structures; air navigation safety.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Antenna structures; air navigation safety. 27... SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.56 Antenna structures; air navigation safety. A licensee that owns its antenna structure(s) must not allow such antenna structure(s) to...

  1. Antenna pattern measurements to characterize the out-of-band behavior of reflector antennas

    NASA Astrophysics Data System (ADS)

    Cown, B. J.; Weaver, E. E.; Ryan, C. E., Jr.

    1983-12-01

    Research was conducted to collect and describe out-of-band antenna pattern data. The research efforts were devoted: (1) to deriving valid measured data for a reflector antenna for out-of-band frequencies spanning intervals around the second and third harmonics of the in-band design frequency, and (2) to statistically characterize the measured data. The second harmonic data were collected for both polarization senses for the out-of-band frequencies of 5.5 GHz to 7.5 GHz in steps of 0.1 GHz. The third harmonic data were collected for both polarization senses for the out-of-band frequencies of 8.0 GHz to 10.0 GHz in steps of 0.1 GHz. Additionally, in-band data were collected at 2.9, 3.0, and 3.1 GHz for both polarization senses. The measured data were collected on the Georgia Tech compact antenna range test facility with the aid of an automated data logger system designed expressly for efficient collection of broadband antenna data. The pattern data, recorded directly on magnetic disks, were analyzed: (1) to compute average gain and standard deviation over selected angular sectors, (2) to construct cumulative probability curves, and (3) to specify the peak gain and the angular coordinates of the peak at each frequency.

  2. MSU Antenna Pattern Data

    NASA Technical Reports Server (NTRS)

    Mo, Tsan; Kleespies, Thomas J.; Green, J. Philip

    2000-01-01

    The Microwave Sounding Unit (MSU) antenna pattern data for nine MSU Flight Models (FMs) have been successfully rescued from 22-year old 7-track and 9-track magnetic tapes and cartridges. These antenna pattern data were unpacked into user-friendly ASCII format, and are potentially useful for making antenna pattern corrections to MSU antenna temperatures in retrieving the true brightness temperatures. We also properly interpreted the contents of the data and show how to convert the measured antenna signal amplitude in volts into relative antenna power in dB with proper normalization. It is found that the data are of high quality with a 60-dB drop in the co-polarized antenna patterns from the central peak value to its side-lobe regions at scan angles beyond 30 deg. The unpacked antenna pattern data produced in this study provide a useful database for data users to correct the antenna side-lobe contribution to MSU measurements. All of the data are available to the scientific community on a single CD-ROM.

  3. Low-SAR metamaterial-inspired printed monopole antenna

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    In this paper, a low-SAR metamaterial-embedded planar monopole antenna is introduced for a wireless communication system. A printed monopole antenna is designed for modern mobile, which operates in GSM, UMTS, LTE, WLAN, and Bluetooth frequency bands. A metamaterial structure is designed to use in the mobile handset with a multi-band printed monopole antenna. The finite integration technique of the CST microwave studio is used in this study. The measurement of antenna performances is taken in an anechoic chamber, and the SAR values are measured using COMOSAR system. The results indicate that metamaterial structure leads to reduce SAR without affecting antenna performance significantly. According to the measured results, the metamaterial attachment leads to reduce 87.7% peak SAR, 68.2% 1-g SAR, and 46.78% 10-g SAR compared to antenna without metamaterial.

  4. Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics.

    PubMed

    Nagayama, Y; Ito, N; Kuwahara, D; Tsuchiya, H; Yamaguchi, S

    2017-04-01

    The two-dimensional (2-D) Horn-antenna Millimeter-wave Imaging Device (HMID) has been developed for the O-mode Microwave Imaging Reflectometry (O-MIR) in the Large Helical Device (LHD). The detectable frequency range of the HMID is 23-33 GHz, which corresponds to the cutoff electron density of 0.8-1.5 × 10 19 m -3 in the O-MIR. The HMID is a 2-D imaging device that improves on the horn-antenna mixer array, which had been developed for the X-mode MIR in the LHD. In the HMID, the signal (RF) wave from the horn antenna is transmitted to the microstrip line by the finline transmitter, and this is mixed by the double-balanced-mixer with the local oscillation wave that is fed by a coaxial cable. By using the HMID, the MIR optical system can be significantly simplified.

  5. A new fabrication method for precision antenna reflectors for space flight and ground test

    NASA Technical Reports Server (NTRS)

    Sharp, G. Richard; Wanhainen, Joyce S.; Ketelsen, Dean A.

    1991-01-01

    Communications satellites are using increasingly higher frequencies that require increasingly precise antenna reflectors for use in space. Traditional industry fabrication methods for space antenna reflectors employ successive modeling techniques using high- and low-temperature molds for reflector face sheets and then a final fit-up of the completed honeycomb sandwich panel antenna reflector to a master pattern. However, as new missions are planned at much higher frequencies, greater accuracies will be necessary than are achievable using these present methods. A new approach for the fabrication of ground-test solid-surface antenna reflectors is to build a rigid support structure with an easy-to-machine surface. This surface is subsequently machined to the desired reflector contour and coated with a radio-frequency-reflective surface. This method was used to fabricate a 2.7-m-diameter ground-test antenna reflector to an accuracy of better than 0.013 mm (0.0005 in.) rms. A similar reflector for use on spacecraft would be constructed in a similar manner but with space-qualified materials. The design, analysis, and fabrication of the 2.7-m-diameter precision antenna reflector for antenna ground tests and the extension of this technology to precision, space-based antenna reflectors are described.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Roy, Sayan

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

  8. Aperture excited dielectric antennas

    NASA Technical Reports Server (NTRS)

    Crosswell, W. F.; Chatterjee, J. S.; Mason, V. B.; Tai, C. T.

    1974-01-01

    The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading.

  9. Modern Antenna Design Using Computers and Measurement: Application to Antenna Problems of Military Interest

    DTIC Science & Technology

    1989-01-01

    admittance of a dipole antenna co’puted Fig. 2. Input admittance of a A/2 dipole antenna corn - by NEC-3S, NEC-3D and NEC3VLF. The dipole was puted by...The upper half space is air, the corn - results are incorrect as a result of using the reflection plex relative permittivity of the medium surrounding...UNCLASSIFIED UNLIMITED (U) ANAFTIM AIUI 87-03964 UNCLASSIFIED UNLIMITED STC Defence Systems, Paigonton (England) (U) AIRIAFT IJ= ANITEIAS AGAR -LS-151

  10. Large-Aperture Membrane Active Phased-Array Antennas

    NASA Technical Reports Server (NTRS)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  11. A Very Compact and Low Profile UWB Planar Antenna with WLAN Band Rejection.

    PubMed

    Syed, Avez; Aldhaheri, Rabah W

    2016-01-01

    A low-cost coplanar waveguide fed compact ultrawideband (UWB) antenna with band rejection characteristics for wireless local area network (WLAN) is proposed. The notch band characteristic is achieved by etching half wavelength C-shaped annular ring slot in the radiating patch. By properly choosing the radius and position of the slot, the notch band can be adjusted and controlled. With an overall size of 18.7 mm × 17.6 mm, the antenna turns out to be one of the smallest UWB antennas with band-notched characteristics. It has a wide fractional bandwidth of 130% (2.9-13.7 GHz) with VSWR < 2 and rejecting IEEE 802.11a and HIPERLAN/2 frequency band of 5.1-5.9 GHz. Stable omnidirectional radiation patterns in the H plane with an average gain of 4.4 dBi are obtained. The band-notch mechanism of the proposed antenna is examined by HFSS simulator. A good agreement is found between measured and simulated results indicating that the proposed antenna is well suited for integration into portable devices for UWB applications.

  12. Optimal Design of a Planar Textile Antenna for Industrial Scientific Medical (ISM) 2.4 GHz Wireless Body Area Networks (WBAN) with the CRO-SL Algorithm.

    PubMed

    Sánchez-Montero, Rocío; Camacho-Gómez, Carlos; López-Espí, Pablo-Luís; Salcedo-Sanz, Sancho

    2018-06-21

    This paper proposes a low-profile textile-modified meander line Inverted-F Antenna (IFA) with variable width and spacing meanders, for Industrial Scientific Medical (ISM) 2.4-GHz Wireless Body Area Networks (WBAN), optimized with a novel metaheuristic algorithm. Specifically, a metaheuristic known as Coral Reefs Optimization with Substrate Layer (CRO-SL) is used to obtain an optimal antenna for sensor systems, which allows covering properly and resiliently the 2.4⁻2.45-GHz industrial scientific medical bandwidth. Flexible pad foam has been used to make the designed prototype with a 1.1-mm thickness. We have used a version of the algorithm that is able to combine different searching operators within a single population of solutions. This approach is ideal to deal with hard optimization problems, such as the design of the proposed meander line IFA. During the optimization phase with the CRO-SL, the proposed antenna has been simulated using CST Microwave Studio software, linked to the CRO-SL by means of MATLAB implementation and Visual Basic Applications (VBA) code. We fully describe the antenna design process, the adaptation of the CRO-SL approach to this problem and several practical aspects of the optimization and details on the algorithm’s performance. To validate the simulation results, we have constructed and measured two prototypes of the antenna, designed with the proposed algorithm. Several practical aspects such as sensitivity during the antenna manufacturing or the agreement between the simulated and constructed antenna are also detailed in the paper.

  13. PATL: A RFID Tag Localization based on Phased Array Antenna.

    PubMed

    Qiu, Lanxin; Liang, Xiaoxuan; Huang, Zhangqin

    2017-03-15

    In RFID systems, how to detect the position precisely is an important and challenging research topic. In this paper, we propose a range-free 2D tag localization method based on phased array antenna, called PATL. This method takes advantage of the adjustable radiation angle of the phased array antenna to scan the surveillance region in turns. By using the statistics of the tags' number in different antenna beam directions, a weighting algorithm is used to calculate the position of the tag. This method can be applied to real-time location of multiple targets without usage of any reference tags or additional readers. Additionally, we present an optimized weighting method based on RSSI to increase the locating accuracy. We use a Commercial Off-the-Shelf (COTS) UHF RFID reader which is integrated with a phased array antenna to evaluate our method. The experiment results from an indoor office environment demonstrate the average distance error of PATL is about 21 cm and the optimized approach achieves an accuracy of 13 cm. This novel 2D localization scheme is a simple, yet promising, solution that is especially applicable to the smart shelf visualized management in storage or retail area.

  14. A multifunctional solar panel antenna for cube satellites

    NASA Astrophysics Data System (ADS)

    Fawole, Olutosin C.

    The basic cube satellite (CubeSat) is a modern small satellite that has a standard size of about one liter (the 1U CubeSat). Three 1U CubeSats could be stacked to form a 3U CubeSat. Their low-cost, short development time, and ease of deployment make CubeSats popular for space research, geographical information gathering, and communication applications. An antenna is a key part of the CubeSat communication subsystem. Traditionally, antennas used on CubeSats are wrapped-up wire dipole antennas, which are deployed after satellite launch. Another antenna type used on CubeSats is the patch antenna. In addition to their low gain and efficiency, deployable dipole antennas may also fail to deploy on satellite launch. On the other hand, a solid patch antenna will compete for space with solar cells when placed on a CubeSat face, interfering with satellite power generation. Slot antennas are promising alternatives to dipole and patch antennas on CubeSats. When excited, a thin slot aperture etched on a conductive sheet (ground plane) is an efficient bidirectional radiator. This open slot antenna can be backed by a reflector or cavity for unidirectional radiation, and solar cells can be placed in spaces on the ground plane not occupied by the slot. The large surface areas of 3U CubeSats can be exploited for a multifunctional antenna by integrating multiple thin slot radiators, which are backed by a thin cavity on the CubeSat surfaces. Solar cells can then be integrated on the antenna surface. Polarization diversity and frequency diversity improve the overall performance of a communication system. Having a single radiating structure that could provide these diversities is desired. It has been demonstrated that when a probe excites a square cavity with two unequal length crossed-slots, the differential radiation from the two slots combines in the far-field to yield circular polarization. In addition, it has been shown that two equal-length proximal slots, when both fed with a

  15. 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.

  16. Cup Cylindrical Waveguide Antenna

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.; Darby, William G.; Kory, Carol L.; Lambert, Kevin M.; Breen, Daniel P.

    2008-01-01

    The cup cylindrical waveguide antenna (CCWA) is a short backfire microwave antenna capable of simultaneously supporting the transmission or reception of two distinct signals having opposite circular polarizations. Short backfire antennas are widely used in mobile/satellite communications, tracking, telemetry, and wireless local area networks because of their compactness and excellent radiation characteristics. A typical prior short backfire antenna contains a half-wavelength dipole excitation element for linear polarization or crossed half-wavelength dipole elements for circular polarization. In order to achieve simultaneous dual circular polarization, it would be necessary to integrate, into the antenna feed structure, a network of hybrid components, which would introduce significant losses. The CCWA embodies an alternate approach that entails relatively low losses and affords the additional advantage of compactness. The CCWA includes a circular cylindrical cup, a circular disk subreflector, and a circular waveguide that serves as the excitation element. The components that make it possible to obtain simultaneous dual circular polarization are integrated into the circular waveguide. These components are a sixpost polarizer and an orthomode transducer (OMT) with two orthogonal coaxial ports. The overall length of the OMT and polarizer (for the nominal middle design frequency of 2.25 GHz) is about 11 in. (approximately equal to 28 cm), whereas the length of a commercially available OMT and polarizer for the same frequency is about 32 in. (approximately equal to 81 cm).

  17. Bandwidth enhancement of a dual band planar monopole antenna using meandered microstrip feeding.

    PubMed

    Ahsan, M R; Islam, M T; Habib Ullah, M; Misran, N

    2014-01-01

    A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (ε r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the -10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz-1 GHz) and at upper band is 28% (2.25 GHz-2.95 GHz). The measured maximum gains of -1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications.

  18. Terahertz emission from the intrinsic Josephson junctions of high-symmetry thermally-managed Bi2Sr2CaCu2O8+δ microstrip antennas

    NASA Astrophysics Data System (ADS)

    Klemm, Richard A.; Davis, Andrew E.; Wang, Qing X.; Yamamoto, Takashi; Cerkoney, Daniel P.; Reid, Candy; Koopman, Maximiliaan L.; Minami, Hidetoshi; Kashiwagi, Takanari; Rain, Joseph R.; Doty, Constance M.; Sedlack, Michael A.; Morales, Manuel A.; Watanabe, Chiharu; Tsujimoto, Manabu; Delfanazari, Kaveh; Kadowaki, Kazuo

    2017-12-01

    We show for high-symmetry disk, square, or equilateral triangular thin microstrip antennas of any composition respectively obeying C ∞v , C 4v , and C 3v point group symmetries, that the transverse magnetic electromagnetic cavity mode wave functions are restricted in form to those that are one-dimensional representations of those point groups. Plots of the common nodal points of the ten lowest-energy non-radiating two-dimensional representations of each of these three symmetries are presented. For comparison with symmetry-broken disk intrinsic Josephson junction microstrip antennas constructed from the highly anisotropic layered superconductor Bi2Sr2CaCu2O8+δ (BSCCO), we present plots of the ten lowest frequency orthonormal wave functions and of their emission power angular distributions. These results are compared with previous results for square and equilateral triangular thin microstrip antennas.

  19. View north of the antenna array, note the communications antenna ...

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

    View north of the antenna array, note the communications antenna in the middleground - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  20. Cellular Reflectarray Antenna

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2010-01-01

    The cellular reflectarray antenna is intended to replace conventional parabolic reflectors that must be physically aligned with a particular satellite in geostationary orbit. These arrays are designed for specified geographical locations, defined by latitude and longitude, each called a "cell." A particular cell occupies nominally 1,500 square miles (3,885 sq. km), but this varies according to latitude and longitude. The cellular reflectarray antenna designed for a particular cell is simply positioned to align with magnetic North, and the antenna surface is level (parallel to the ground). A given cellular reflectarray antenna will not operate in any other cell.

  1. A Spatial-frequency Method for Analyzing Antenna-to-Probe Interactions in Near-field Antenna Measurements.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brock, Billy C.

    The measurement of the radiation characteristics of an antenna on a near-field range requires that the antenna under test be located very close to the near-field probe. Although the direct coupling is utilized for characterizing the near field, this close proximity also presents the opportunity for significant undesired interactions (for example, reflections) to occur between the antenna and the near-field probe. When uncompensated, these additional interactions will introduce error into the measurement, increasing the uncertainty in the final gain pattern obtained through the near-field-to-far-field transformation. Quantifying this gain-uncertainty contribution requires quantifying the various additional interactions. A method incorporating spatial-frequency analysismore » is described which allows the dominant interaction contributions to be easily identified and quantified. In addition to identifying the additional antenna-to-probe interactions, the method also allows identification and quantification of interactions with other nearby objects within the measurement room. Because the method is a spatial-frequency method, wide-bandwidth data is not required, and it can be applied even when data is available at only a single temporal frequency. This feature ensures that the method can be applied to narrow-band antennas, where a similar time-domain analysis would not be possible. - 3 - - 4 -« less

  2. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Performance Verification Report: METSAT AMSU-A2 Antenna Drive Subsystem, P/N 1331200-2, S/N 106

    NASA Technical Reports Server (NTRS)

    Higgins, T.

    1998-01-01

    An antenna drive subsystem test was performed on the METSAT AMSU-A2 S/N 106 instrument. The objective of the test was to demonstrate compliance with applicable paragraphs of AMSU-A specifications S480-80. Tests were conducted at both the subassembly and instrument level.

  3. Design of Dual Band Microstrip Patch Antenna using Metamaterial

    NASA Astrophysics Data System (ADS)

    Rafiqul Islam, Md; Alsaleh Adel, A. A.; Mimi, Aminah W. N.; Yasmin, M. Sarah; Norun, Farihah A. M.

    2017-11-01

    Metamaterial has received great attention due to their novel electromagnetic properties. It consists of artificial metallic structures with negative permittivity (ɛ) and permeability (µ). The average cell size of metamaterial must be less than a quarter of wavelength, hence, size reduction for the metamaterial antenna is possible. In addition, metamaterial can be used to enhance the low gain and efficiency in conventional patch antenna, which is important in wireless communication. In this paper, dual band microstrip patch antenna design using metamaterial for mobile GSM and WiMax application is introduced. The antenna structure consists of microstrip feed line connected to a rectangular patch. An array of five split ring resonators (SRRs) unit cells is inserted under the patch. The presented antenna resonates at 1.8 GHz for mobile GSM and 2.4 GHz for WIMAX applications. The return loss in the FR4 antenna at 1.8 GHz is -22.5 dB. Using metamaterial the return loss has improved to -25 dB at 2.4 GHz and -23.5 dB at 1.8 GHz. A conventional microstrip patch antenna using pair of slots is also designed which resonates at 1.8 GHz and 2.4 GHz. The return loss at 1.8 GHz and 2.4 GHz were -12.1 dB and -21.8 dB respectively. The metamaterial antenna achieved results with major size reduction of 45%, better bandwidth and better returns loss if it is compared to the pair of slots antenna. The software used to design, simulate and optimize is CST microwave studio.

  4. L-band mobile terminal antennas for helicopters

    NASA Technical Reports Server (NTRS)

    Wu, T. K.; Farazian, K.; Golshan, N.; Divsalar, D.; Hinedi, S.

    1993-01-01

    The feasibility of using a low gain antenna (LGA) as a mobile terminal antenna for a helicopter is described in this paper. The objectives are to select the lowest cost antenna system which can be easily mounted on a helicopter and capable of communicating with a satellite, and to determine the best antenna position on the helicopter to mitigate the signal blockage due to rotor blades and the multipath effect from the helicopter's body. The omnidirectional LGA is selected because it is simple, reliable, and low cost. The helix antenna is selected among the many LGA's because it is the most economical one and has the widest elevation beamwidth. Both 2-arm and 4-arm helices are studied experimentally to determine the antenna's performance and the scattering effects from the helicopter's body. It is found that the LGA should be located near the tail section and at least eight inches above the helicopter.

  5. 47 CFR 90.1321 - Power and antenna limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Power and antenna limits. 90.1321 Section 90... and antenna limits. (a) Base and fixed stations are limited to 25 watts/25 MHz equivalent... receiver. (2) If the transmitter employs an antenna system that emits multiple directional beams but does...

  6. 47 CFR 90.1321 - Power and antenna limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Power and antenna limits. 90.1321 Section 90... and antenna limits. (a) Base and fixed stations are limited to 25 watts/25 MHz equivalent... receiver. (2) If the transmitter employs an antenna system that emits multiple directional beams but does...

  7. 47 CFR 90.1321 - Power and antenna limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Power and antenna limits. 90.1321 Section 90... and antenna limits. (a) Base and fixed stations are limited to 25 watts/25 MHz equivalent... receiver. (2) If the transmitter employs an antenna system that emits multiple directional beams but does...

  8. 47 CFR 90.1321 - Power and antenna limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Power and antenna limits. 90.1321 Section 90... and antenna limits. (a) Base and fixed stations are limited to 25 watts/25 MHz equivalent... receiver. (2) If the transmitter employs an antenna system that emits multiple directional beams but does...

  9. 47 CFR 90.1321 - Power and antenna limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Power and antenna limits. 90.1321 Section 90... and antenna limits. (a) Base and fixed stations are limited to 25 watts/25 MHz equivalent... receiver. (2) If the transmitter employs an antenna system that emits multiple directional beams but does...

  10. 18. View from DR 2 antenna looking south 45 degrees ...

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

    18. View from DR 2 antenna looking south 45 degrees west to backside transmitter building 101 and in left foreground showing site well system building. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  11. Mode Matching for Optical Antennas

    NASA Astrophysics Data System (ADS)

    Feichtner, Thorsten; Christiansen, Silke; Hecht, Bert

    2017-11-01

    The emission rate of a point dipole can be strongly increased in the presence of a well-designed optical antenna. Yet, optical antenna design is largely based on radio-frequency rules, ignoring, e.g., Ohmic losses and non-negligible field penetration in metals at optical frequencies. Here, we combine reciprocity and Poynting's theorem to derive a set of optical-frequency antenna design rules for benchmarking and optimizing the performance of optical antennas driven by single quantum emitters. Based on these findings a novel plasmonic cavity antenna design is presented exhibiting a considerably improved performance compared to a reference two-wire antenna. Our work will be useful for the design of high-performance optical antennas and nanoresonators for diverse applications ranging from quantum optics to antenna-enhanced single-emitter spectroscopy and sensing.

  12. Mode Theory of Multi-Armed Spiral Antennas and Its Application to Electronic Warfare Antennas

    NASA Astrophysics Data System (ADS)

    Radway, Matthew J.

    Since their invention about 55 years ago, spiral antennas have earned a reputation for providing stable impedance and far-field patterns over multi-decade frequency ranges. For the first few decades these antennas were researched for electronic warfare receiving applications, primarily in the 2-18 GHz range. This research was often done under conditions of secrecy, and often by private contractors who did not readily share their research, and now have been defunct for decades. Even so, the body of literature on the two-armed variant of these antennas is rich, often leading non-specialists to the misconception that these antennas are completely understood. Furthermore, early work was highly experimental in nature, and was conducted before modern data collection and postprocessing capabilities were widespread, which limited the range of the studies. Recent research efforts have focused on extending the application of spirals into new areas, as well as applying exotic materials to `improve' their performance and reduce their size. While interesting results have been obtained, in most instances these were incomplete, often compromising the frequency independent nature of these antennas. This thesis expands the role of the multi-armed spiral outside of its traditional niche of receive-only monopulse direction finding. As a first step, careful study of the spiral-antenna mode theory is undertaken with particular attention paid to the concepts of mode filtering and modal decomposition. A technique for reducing the modal impedance of high arm-count spirals is introduced. The insights gained through this theoretical study are first used to improve the far-field performance of the coiled-arm spiral antenna. Specifically, expanding the number of arms on a coiled arm spiral from two to four while providing proper excitation enables dramatically improved broadside axial ratio and azimuthal pattern uniformity. The multiarming technique is then applied to the design of an antenna

  13. Rectangular Microstrip Antenna with Slot Embedded Geometry

    NASA Astrophysics Data System (ADS)

    Ambresh, P. A.; Hadalgi, P. M.; Hunagund, P. V.; Sujata, A. A.

    2014-09-01

    In this paper, a novel design that improves the performance of conventional rectangular microstrip antenna is discussed. Design adopts basic techniques such as probe feeding technique with rectangular inverted patch structure as superstrate, air filled dielectric medium as substrate and slot embedded patch. Prototype of the proposed antenna has been fabricated and various antenna performance parameters such as impedance bandwidth, return loss, radiation pattern and antenna gain are considered for Electromagnetic-study. The antennas are designed for the wireless application operating in the frequency range of 3.3 GHz to 3.6 GHz, and UK based fixed satellite service application (3 GHz to 4 GHz), and are named as single inverted patch conventional rectangular microstrip antenna (SIP-CRMSA) and slots embedded inverted patch rectangular microstrip antenna (SEIP-RMSA), respectively. Measurement outcomes for SEIP-RMSA1 and SEIP-RMSA2 showed the satisfactory performance with an achievable impedance bandwidth of 260 MHz (7 %) and 250 MHz (6.72 %), with return loss (RL) of -11.06 dB and -17.98 dB, achieved gain of 8.17 dB and 5.17 dB with 10% and 8% size reduction in comparison with the conventional patch antenna.

  14. Antenna pattern study, task 2

    NASA Technical Reports Server (NTRS)

    Harper, Warren

    1989-01-01

    Two electromagnetic scattering codes, NEC-BSC and ESP3, were delivered and installed on a NASA VAX computer for use by Marshall Space Flight Center antenna design personnel. The existing codes and certain supplementary software were updated, the codes installed on a computer that will be delivered to the customer, to provide capability for graphic display of the data to be computed by the use of the codes and to assist the customer in the solution of specific problems that demonstrate the use of the codes. With the exception of one code revision, all of these tasks were performed.

  15. The fate of the Antennae galaxies

    NASA Astrophysics Data System (ADS)

    Lahén, Natalia; Johansson, Peter H.; Rantala, Antti; Naab, Thorsten; Frigo, Matteo

    2018-04-01

    We present a high-resolution smoothed particle hydrodynamic simulation of the Antennae galaxies (NGC 4038/4039) and follow the evolution 3 Gyr beyond the final coalescence. The simulation includes metallicity-dependent cooling, star formation, and both stellar feedback and chemical enrichment. The simulated best-match Antennae reproduce well both the observed morphology and the off-nuclear starburst. We also produce for the first time a simulated two-dimensional (2D) metallicity map of the Antennae and find good agreement with the observed metallicity of off-nuclear stellar clusters; however, the nuclear metallicities are overproduced by ˜0.5 dex. Using the radiative transfer code SKIRT, we produce multiwavelength observations of both the Antennae and the merger remnant. The 1-Gyr-old remnant is well fitted with a Sérsic profile of n = 7.07, and with an r-band effective radius of re = 1.6 kpc and velocity dispersion of σe = 180 km s-1 the remnant is located on the Fundamental Plane of early-type galaxies (ETGs). The initially blue Antennae remnant evolves on to the red sequence after ˜2.5 Gyr of secular evolution. The remnant would be classified as a fast rotator, as the specific angular momentum evolves from λRe ≈ 0.11 to 0.14 during its evolution. The remnant shows ordered rotation and a double peaked maximum in the mean 2D line-of-sight velocity. These kinematical features are relatively common amongst local ETGs and we specifically identify three local ETGs (NGC 3226, NGC 3379, and NGC 4494) in the atlas3D sample, whose photometric and kinematic properties most resemble the Antennae remnant.

  16. A Very Compact and Low Profile UWB Planar Antenna with WLAN Band Rejection

    PubMed Central

    Syed, Avez; Aldhaheri, Rabah W.

    2016-01-01

    A low-cost coplanar waveguide fed compact ultrawideband (UWB) antenna with band rejection characteristics for wireless local area network (WLAN) is proposed. The notch band characteristic is achieved by etching half wavelength C-shaped annular ring slot in the radiating patch. By properly choosing the radius and position of the slot, the notch band can be adjusted and controlled. With an overall size of 18.7 mm × 17.6 mm, the antenna turns out to be one of the smallest UWB antennas with band-notched characteristics. It has a wide fractional bandwidth of 130% (2.9–13.7 GHz) with VSWR < 2 and rejecting IEEE 802.11a and HIPERLAN/2 frequency band of 5.1–5.9 GHz. Stable omnidirectional radiation patterns in the H plane with an average gain of 4.4 dBi are obtained. The band-notch mechanism of the proposed antenna is examined by HFSS simulator. A good agreement is found between measured and simulated results indicating that the proposed antenna is well suited for integration into portable devices for UWB applications. PMID:27088125

  17. Experimental Measurements of the Dynamic Electric Field Topology Associated with Magnetized RF Sheaths

    NASA Astrophysics Data System (ADS)

    Martin, E. H.; Caughman, J. B. O.; Shannon, S. C.; Klepper, C. C.; Isler, R. C.

    2013-10-01

    A major challenge facing magnetic fusion devices and the success of ITER is the design and implementation of reliable ICRH systems. The primary issue facing ICRH is the parasitic near-field which leads to an increased heat flux, sputtering, and arcing of the antenna/faraday screen. In order to aid the theoretical development of near-field physics and thus propel the design process experimental measurements are highly desired. In this work we have developed a diagnostic based on passive emission spectroscopy capable of measuring time periodic electric fields utilizing a generalized dynamic Stark effect model and a novel spectral line profile fitting package. The diagnostic was implemented on a small scale laboratory experiment designed to simulate the edge environment associated with ICRF antenna/faraday screen. The spatially and temporally resolved electric field associated with magnetized RF sheaths will be presented for two field configurations: magnetic field parallel to electric field and magnetic field perpendicular to electric field, both hydrogen and helium discharges where investigated. ORNL is managed by UT-Battelle, LCC, for the US DOE under Contract No. DE-AC05-00OR22725.

  18. Antenna Impedance Measures in a Magnetized Plasma. Part 1. Spherical Antenna

    DTIC Science & Technology

    2006-10-16

    3436 (1964) [2] Crawford FW, J. Appl. Phys 36 (10) 3142, (1965) [3] Dote T , Ichimiya T , Journal of Applied Physics 36 (6): 1866 (1965) [4] Oya H...Obayashi T , Report of Ionosphere and Space Research in Japan 20 (2): 199 (1966) [5] Balmain, K. IEEE Transactions on Antennas and Propagation vol.AP-14...no.3 : 402 (1966) [6] Uramoto J Physics Of Fluids 13 (3): 657 (1970) 5 [7] T . H. Y. Yeung and J. Sayers, Proc. Phys. Soc. London, Sect. B 70, 663

  19. A broadband and low cross polarization antenna with a balun of microstrip line coupling to slot line

    PubMed Central

    Sun, Kai; Liu, Sihao; Yang, Tianming

    2018-01-01

    In this paper, a wide-band low cross polarization antenna with a structure of microstrip line coupling to slot line as the balun is proposed. The radiation part of the antenna is fed by two pairs of parallel transmission line via a transition from a slot line which is coupled by a microstrip line. Because it is fed by parallel transmission lines, which is balanced-fed structure, the antenna can achieve an improved low cross-polarization performance. The height of the antenna is 0.146λ0 (λ0 is the wavelength of lowest frequency). The prototype antenna demonstrates a measured impedance bandwidth of 93.5% (2.7–7.44 GHz), a 3-dB-gain bandwidth of 77% (2.7–6.1 GHz), and a maximum gain of 10.5 dBi at 4.5 GHz. PMID:29543902

  20. A broadband and low cross polarization antenna with a balun of microstrip line coupling to slot line.

    PubMed

    Sun, Kai; Yang, Deqiang; Liu, Sihao; Yang, Tianming

    2018-01-01

    In this paper, a wide-band low cross polarization antenna with a structure of microstrip line coupling to slot line as the balun is proposed. The radiation part of the antenna is fed by two pairs of parallel transmission line via a transition from a slot line which is coupled by a microstrip line. Because it is fed by parallel transmission lines, which is balanced-fed structure, the antenna can achieve an improved low cross-polarization performance. The height of the antenna is 0.146λ0 (λ0 is the wavelength of lowest frequency). The prototype antenna demonstrates a measured impedance bandwidth of 93.5% (2.7-7.44 GHz), a 3-dB-gain bandwidth of 77% (2.7-6.1 GHz), and a maximum gain of 10.5 dBi at 4.5 GHz.

  1. A Polarization Reconfigurable Slot Antenna with a Novel Switchable Feeding Network

    NASA Astrophysics Data System (ADS)

    Xie, Peng; Wang, Guang Ming

    2017-12-01

    A polarization reconfigurable slot antenna is proposed in this paper. The antenna consists of a microstrip line-to-slotline transition structure, two radiation slots and a switchable feeding network. The feeding network is a gradually changed ring slot with six switching diodes on it. By controlling the diodes states, the antenna can generate y-direction polarization, z-direction polarization, left-hand circular polarization and right-hand circular polarization. Detailed design considerations of the proposed antenna, simulated and measured results are presented and discussed. Measured results agree well with simulated. The results proved that the antenna can realize polarization reconfiguration effectively at 5 GHz.

  2. Multibeam antenna study, phase 1

    NASA Technical Reports Server (NTRS)

    Bellamy, J. L.

    1972-01-01

    A multibeam antenna concept was developed for providing spot beam coverage of the contiguous 48 states. The selection of a suitable antenna concept for the multibeam application and an experimental evaluation of the antenna concept selected are described. The final analysis indicates that the preferred concept is a dual-antenna, circular artificial dielectric lens. A description of the analytical methods is provided, as well as a discussion of the absolute requirements placed on the antenna concepts. Finally, a comparative analysis of reflector antenna off-axis beam performance is presented.

  3. Multi-Polarization Reconfigurable Antenna for Wireless Biomedical System.

    PubMed

    Wong, Hang; Lin, Wei; Huitema, Laure; Arnaud, Eric

    2017-06-01

    This paper presents a multi-polarization reconfigurable antenna with four dipole radiators for biomedical applications in body-centric wireless communication system (BWCS). The proposed multi-dipole antenna with switchable 0°, +45°, 90° and -45° linear polarizations is able to overcome the polarization mismatching and multi-path distortion in complex wireless channels as in BWCS. To realize this reconfigurable feature for the first time among all the reported antenna designs, we assembled four dipoles together with 45° rotated sequential arrangements. These dipoles are excited by the same feeding source provided by a ground tapered Balun. A metallic reflector is placed below the dipoles to generate a broadside radiation. By introducing eight PIN diodes as RF switches between the excitation source and the four dipoles, we can control a specific dipole to operate. As the results, 0°, +45°, 90° and -45° linear polarizations can be switched correspondingly to different operating dipoles. Experimental results agree with the simulation and show that the proposed antenna well works in all polarization modes with desirable electrical characteristics. The antenna has a wide impedance bandwidth of 34% from 2.2 to 3.1 GHz (for the reflection coefficient ≤ -10 dB) and exhibits a stable cardioid-shaped radiation pattern across the operating bandwidth with a peak gain of 5.2 dBi. To validate the effectiveness of the multi-dipole antenna for biomedical applications, we also designed a meandered PIFA as the implantable antenna. Finally, the communication link measurement shows that our proposed antenna is able to minimize the polarization mismatching and maintains the optimal communication link thanks to its polarization reconfigurability.

  4. Study of a Flexible Low Profile Tunable Dipole Antenna Using Barium Strontium Titanate Varactors

    NASA Technical Reports Server (NTRS)

    Cure, David; Weller, Thomas; Miranda, Felix A.

    2014-01-01

    In this paper a flexible low profile dipole antenna using a frequency selective surface (FSS) with interdigital barium strontium titanate (BST) varactor-tuned unit cells is presented. The varactor chips were placed only along one dimension of the FSS to avoid the use of vias and simplify the DC bias network. The antenna uses overlapping metallic plates that resemble fish scales as a ground plane to improve the flexibility of the multi-material stack structure. The measured data of the antenna demonstrate tunability from 2.42 GHz to 2.66 GHz and 1.3 dB gain drop when using overlapping metallic plates instead of continuous ground plane. The total antenna thickness is approximately lambda/24.

  5. Comsat Antenna

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The antenna shown is the new, multiple-beam, Unattended Earth Terminal, located at COMSAT Laboratories in Clarksburg, Maryland. Seemingly simple, it is actually a complex structure capable of maintaining contact with several satellites simultaneously (conventional Earth station antennas communicate with only one satellite at a time). In developing the antenna, COMSAT Laboratories used NASTRAN, NASA's structural analysis computer program, together with BANDIT, a companion program. The computer programs were used to model several structural configurations and determine the most suitable, The speed and accuracy of the computerized design analysis afforded appreciable savings in time and money.

  6. 47 CFR 78.105 - Antenna systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... planes. (2) New periscope antenna systems will be authorized upon a certification that the radiation, in... antennas is left to the discretion of the licensee. However, licensees will not be protected from... provisions of this paragraph are effective for all new applications accepted for filing after October 1, 1981...

  7. PATL: A RFID Tag Localization based on Phased Array Antenna

    PubMed Central

    Qiu, Lanxin; Liang, Xiaoxuan; Huang, Zhangqin

    2017-01-01

    In RFID systems, how to detect the position precisely is an important and challenging research topic. In this paper, we propose a range-free 2D tag localization method based on phased array antenna, called PATL. This method takes advantage of the adjustable radiation angle of the phased array antenna to scan the surveillance region in turns. By using the statistics of the tags’ number in different antenna beam directions, a weighting algorithm is used to calculate the position of the tag. This method can be applied to real-time location of multiple targets without usage of any reference tags or additional readers. Additionally, we present an optimized weighting method based on RSSI to increase the locating accuracy. We use a Commercial Off-the-Shelf (COTS) UHF RFID reader which is integrated with a phased array antenna to evaluate our method. The experiment results from an indoor office environment demonstrate the average distance error of PATL is about 21 cm and the optimized approach achieves an accuracy of 13 cm. This novel 2D localization scheme is a simple, yet promising, solution that is especially applicable to the smart shelf visualized management in storage or retail area. PMID:28295014

  8. Bandwidth Enhancement of a Dual Band Planar Monopole Antenna Using Meandered Microstrip Feeding

    PubMed Central

    Ahsan, M. R.; Islam, M. T.; Habib Ullah, M.; Misran, N.

    2014-01-01

    A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (ε r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the −10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz–1 GHz) and at upper band is 28% (2.25 GHz–2.95 GHz). The measured maximum gains of −1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications. PMID:24723832

  9. Miniaturized and reconfigurable notch antenna based on a BST ferroelectric thin film

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nguyen, Hung Viet; CEA-LETI, Minatec, 17 avenue des Martyrs, 38054 Grenoble Cedex 9; Benzerga, Ratiba, E-mail: ratiba.benzerga@univ-rennes1.fr

    Highlights: • A miniature and agile antenna based on a BST MIM capacitor is simulated and made. • Mn{sup 2+} doped BST thin films are synthesized by chemical deposition and spin coating. • Permittivity and losses of the BST thin film are respectively 225 and 0.02 at 1 GHz. • A miniaturization rate of 70% is obtained with a MIM capacitance of 3.7 pF. • A frequency tunability of 14.5% and a tunability performance of 0.04 are measured. - Abstract: This work deals with the design, realization and characterization of a miniature and frequency agile antenna based on a ferroelectricmore » Ba{sub 0,80}Sr{sub 0,20}TiO{sub 3} thin film. The notch antenna is loaded with a variable metal/insulator/metal (MIM) capacitor and is achieved by a monolithic method. The MIM capacitance is 3.7 pF, which results in a resonant frequency of 670 MHz compared to 2.25 GHz for the unloaded simulated antenna; the resulting miniaturization rate is 70%. The characterization of the antenna prototype shows a frequency tunable rate of 14.5% under an electric field of 375 kV/cm, with a tunability performance η = 0.04.« less

  10. Multi-band Monopole Antennas Loaded with Metamaterial TL

    NASA Astrophysics Data System (ADS)

    Song, Zhi-jie; Liang, Jian-gang

    2015-05-01

    A novel metamaterial transmission line (TL) by loading complementary single Archimedean spiral resonator pair (CSASRP) is investigated and used to design a set of multi-frequency monopole antennas. The particularity is that the CSASRP which features dual-shunt branches in the equivalent circuit model is directly etched in the signal strip. By smartly controlling the element parameters, three antennas are designed and one of them covering UMTS and Bluetooth bands is fabricated and measured. The antenna exhibits impedance matching better than -10 dB and normal monopolar radiation patterns at working bands of 1.9-2.22 and 2.38-2.5 GHz. Moreover, the loaded element also contributes to the radiation, which is the major advantage of this prescription over previous lumped-element loadings. The proposed antenna is also more compact over previous designs.

  11. Low Profile Tunable Dipole Antennas Using BST Varactors for Biomedical Applications

    NASA Technical Reports Server (NTRS)

    Cure, David; Weller, Thomas; Price, Tony; Miranda, Felix A.

    2013-01-01

    In this presentation a 2.4 GHz low profile (lambda45) tunable dipole antenna is evaluated in the presence of a human core model (HCM) body phantom. The antenna uses a frequency selective surface (FSS) with interdigital barium strontium titanate (BST) varactor-tuned unit cells and its performance is compared to a similar low profile antenna that uses an FSS with semiconductor varactor diodes. The measured data of the antenna demonstrate tunability from 2.2 GHz to 2.55 GHz in free space and impedance match improvement in the presence of a HCM at different distances. This antenna has smaller size, lower cost and less weight compared to the semiconductor varactor diode counterpart.

  12. Low Profile Tunable Dipole Antenna Using BST Varactors for Biomedical Applications

    NASA Technical Reports Server (NTRS)

    Cure, David; Weller, Thomas M.; Miranda, Felix A.; Price, Tony

    2013-01-01

    In this paper a 2.4 GHz low profile (lambda/47) tunable dipole antenna is evaluated in the presence of a human core model (HCM) body phantom. The antenna uses a frequency selective surface (FSS) with interdigital barium strontium titanate (BST) varactor-tuned unit cells and its performance is compared to a similar low profile antenna that uses an FSS with semiconductor varactor diodes. The measured data of the antenna demonstrate tunability from 2.2 GHz to 2.55 GHz in free space and impedance match improvement in the presence of a HCM at different distances. This antenna has smaller size, lower cost and less weight compared to the semiconductor varactor diode counterpart.

  13. Compact filtering monopole patch antenna with dual-band rejection.

    PubMed

    Kim, Sun-Woong; Choi, Dong-You

    2016-01-01

    In this paper, a compact ultra-wideband patch antenna with dual-band rejection is proposed. The proposed antenna filters 3.3-3.8 GHz WiMAX and 5.15-5.85 GHz WLAN by respectively rejecting these bands through a C-shaped slit and a λg/4 resonator. The λg/4 resonator is positioned as a pair, centered around the microstrip line, and a C-type slit is inserted into an elliptical patch. The impedance bandwidth of the proposed antenna is 2.9-9.3 GHz, which satisfies the bandwidth for ultra-wideband communication systems. Further, the proposed antenna provides dual-band rejection at two bands: 3.2-3.85 and 4.7-6.03 GHz. The radiation pattern of the antenna is omnidirectional, and antenna gain is maintained constantly while showing -8.4 and -1.5 dBi at the two rejected bands, respectively.

  14. High-temperature superconductor antenna investigations

    NASA Technical Reports Server (NTRS)

    Karasack, Vincent G.

    1990-01-01

    The use of superconductors to increase antenna radiation efficiency and gain is examined. Although the gain of all normal-metal antennas can be increased through the use of superconductors, some structures have greater potential for practical improvement than others. Some structures suffer a great degradation in bandwidth when replaced with superconductors, while for others the improvement in efficiency is trivial due to the minimal contribution of the conductor loss mechanism to the total losses, or the already high efficiency of the structure. The following antennas and related structures are discussed: electrically small antennas, impedance matching of antennas, microstrip antennas, microwave and millimeter-wave antenna arrays, and superdirective arrays. The greatest potential practical improvements occur for large microwave and millimeter-wave arrays and the impedance matching of antennas.

  15. Fractal Based Triple Band High Gain Monopole Antenna

    NASA Astrophysics Data System (ADS)

    Pandey, Shashi Kant; Pandey, Ganga Prasad; Sarun, P. M.

    2017-10-01

    A novel triple-band microstrip fed planar monopole antenna is proposed and investigated. A fractal antenna is created by iterating a narrow pulse (NP) generator model at upper side of modified ground plane, which has a rhombic patch, for enhancing the bandwidth and gain. Three iterations are carried out to study the effects of fractal geometry on the antenna performance. The proposed antenna can operate over three frequency ranges viz, 3.34-4.8 GHz, 5.5-10.6 GHz and 13-14.96 GHz suitable for WLAN 5.2/5.8 GHz, WiMAX 3.5/5.5 GHz and X band applications respectively. Simulated and measured results are in good agreements with each others. Results show that antenna provides wide/ultra wide bandwidths, monopole like radiation patterns and very high antenna gains over the operating frequency bands.

  16. Phased-array-fed antenna configuration study, volume 2

    NASA Technical Reports Server (NTRS)

    Sorbello, R. M.; Zaghloul, A. I.; Lee, B. S.; Siddiqi, S.; Geller, B. D.

    1983-01-01

    Increased capacity in future satellite systems can be achieved through antenna systems which provide multiplicity of frequency reuses at K sub a band. A number of antenna configurations which can provide multiple fixed spot beams and multiple independent spot scanning beams at 20 GHz are addressed. Each design incorporates a phased array with distributed MMIC amplifiers and phasesifters feeding a two reflector optical system. The tradeoffs required for the design of these systems and the corresponding performances are presented. Five final designs are studied. In so doing, a type of MMIC/waveguide transition is described, and measured results of the breadboard model are presented. Other hardware components developed are described. This includes a square orthomode transducer, a subarray fed with a beamforming network to measure scanning performance, and another subarray used to study mutual coupling considerations. Discussions of the advantages and disadvantages of the final design are included.

  17. Improved Object Detection Using a Robotic Sensing Antenna with Vibration Damping Control

    PubMed Central

    Feliu-Batlle, Vicente; Feliu-Talegon, Daniel; Castillo-Berrio, Claudia Fernanda

    2017-01-01

    Some insects or mammals use antennae or whiskers to detect by the sense of touch obstacles or recognize objects in environments in which other senses like vision cannot work. Artificial flexible antennae can be used in robotics to mimic this sense of touch in these recognition tasks. We have designed and built a two-degree of freedom (2DOF) flexible antenna sensor device to perform robot navigation tasks. This device is composed of a flexible beam, two servomotors that drive the beam and a load cell sensor that detects the contact of the beam with an object. It is found that the efficiency of such a device strongly depends on the speed and accuracy achieved by the antenna positioning system. These issues are severely impaired by the vibrations that appear in the antenna during its movement. However, these antennae are usually moved without taking care of these undesired vibrations. This article proposes a new closed-loop control schema that cancels vibrations and improves the free movements of the antenna. Moreover, algorithms to estimate the 3D beam position and the instant and point of contact with an object are proposed. Experiments are reported that illustrate the efficiency of these proposed algorithms and the improvements achieved in object detection tasks using a control system that cancels beam vibrations. PMID:28406449

  18. Improved Object Detection Using a Robotic Sensing Antenna with Vibration Damping Control.

    PubMed

    Feliu-Batlle, Vicente; Feliu-Talegon, Daniel; Castillo-Berrio, Claudia Fernanda

    2017-04-13

    Some insects or mammals use antennae or whiskers to detect by the sense of touch obstacles or recognize objects in environments in which other senses like vision cannot work. Artificial flexible antennae can be used in robotics to mimic this sense of touch in these recognition tasks. We have designed and built a two-degree of freedom (2DOF) flexible antenna sensor device to perform robot navigation tasks. This device is composed of a flexible beam, two servomotors that drive the beam and a load cell sensor that detects the contact of the beam with an object. It is found that the efficiency of such a device strongly depends on the speed and accuracy achieved by the antenna positioning system. These issues are severely impaired by the vibrations that appear in the antenna during its movement. However, these antennae are usually moved without taking care of these undesired vibrations. This article proposes a new closed-loop control schema that cancels vibrations and improves the free movements of the antenna. Moreover, algorithms to estimate the 3D beam position and the instant and point of contact with an object are proposed. Experiments are reported that illustrate the efficiency of these proposed algorithms and the improvements achieved in object detection tasks using a control system that cancels beam vibrations.

  19. A dual-slot microwave antenna for more spherical ablation zones: ex vivo and in vivo validation.

    PubMed

    Chiang, Jason; Hynes, Kieran A; Bedoya, Mariajose; Brace, Christopher L

    2013-08-01

    To compare the performance of a microwave antenna design with two annular slots to that of a monopole antenna design in creating a more spherical ablation zone. Animal care and use committee approval was obtained before in vivo experiments were performed. Microwave ablation zones were created by using dual-slot and monopole control antennas for 2, 5, and 10 minutes at 50 and 100 W in ex vivo bovine livers. Dual-slot and monopole antennas were then used to create ablation zones at 100 W for 5 minutes in in vivo porcine livers, which also underwent intraprocedural imaging. Ablation diameter, length, and aspect ratio (diameter ÷ length) were measured at gross pathologic examination and compared at each combination of power and time by using the paired Student t test. A P value less than .05 was considered to indicate a significant difference. Aspect ratios closer to 1 reflected a more spherical ablation zone. The dual-slot antenna created ablation zones with a higher aspect ratio at 50 W for 2 minutes (0.75 vs 0.53, P = .003) and 5 minutes (0.82 vs 0.63, P = .053) than did the monopole antenna in ex vivo liver tissue, although the difference was only significant at 2 minutes. At 100 W, the dual-slot antenna had a significantly higher aspect ratio at 2 minutes (0.52 vs 0.42, P = .002). In vivo studies showed significantly higher aspect ratios at 100 W for 5 minutes (0.63 vs 0.53, respectively, P = .029). Intraprocedural imaging confirmed this characterization, showing higher rates of ablation zone growth and heating primarily at the early stages of the ablation procedure when the dual-slot antenna was used. The dual-slot microwave antenna created a more spherical ablation zone than did the monopole antenna both in vivo and ex vivo liver tissue. Greater control over power delivery can potentially extend the advantages of the dual-slot antenna design to higher power and longer treatment times.

  20. Design and development of conformal antenna composite structure

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

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

  1. 'Invisible' antenna takes up less space

    NASA Astrophysics Data System (ADS)

    Shelley, M.; Bond, K.

    1986-06-01

    A compensated microstrip patch design is described that also uses grounded coplanar waveguide to permit a second, independent antenna to be mounted on any type of existing primary radar antenna aboard an aircraft without affecting its radiation. Successful integration of the IFF (identification friend or foe) antenna, which works at D-band, and the primary radar antenna is possible because of the diversity in frequency between the two antennas. Construction of a microstrip radiating element, electromagnetically invisible to the primary antenna, requires orthogonal grating elements and use of the primary antenna as the ground plane. Coplanar mounting of a stripline array with the primary antenna reduces the manufacturing costs and increases the functional performance of the IFF antenna.

  2. A highly directive graphene antenna embedded inside a Fabry-Perot cavity in terahertz regime

    NASA Astrophysics Data System (ADS)

    Roshanaei, Majid; Karami, Hamidreza; Dehkhoda, Parisa; Esfahani, Hamid; Dabir, Fatemeh

    2018-05-01

    In this paper, a highly directive nano-thickness graphene-based antenna is introduced in the terahertz frequency band. The antenna is a graphene patch dipole which is placed between two Bragg mirrors called Fabry-Perot cavity. Tunability of the graphene's conductivity makes it possible to excite the desired resonances of the cavity. Here, first, a single resonant antenna is introduced at 5 THz with an enhanced gain from 2.11 dBi to 12.8 dBi with a beamwidth of 22.7°. Then, a triple resonant antenna at 4.7, 5 and 5.3 THz is presented with respective gains of 7.97, 11.9 and 8.52 dBi. Finally, the effect of dimensions and number of the dielectric layers of the cavity are studied in order to further increase in directivity.

  3. Wearable slot antenna at 2.45 GHz for off-body radiation: Analysis of efficiency, frequency shift, and body absorption.

    PubMed

    Fernandez, Marta; Espinosa, Hugo G; Thiel, David V; Arrinda, Amaia

    2018-01-01

    The interaction of body-worn antennas with the human body causes a significant decrease in antenna efficiency and a shift in resonant frequency. A resonant slot in a small conductive box placed on the body has been shown to reduce these effects. The specific absorption rate is less than international health standards for most wearable antennas due to small transmitter power. This paper reports the linear relationship between power absorbed by biological tissues at different locations on the body and radiation efficiency based on numerical modeling (r = 0.99). While the -10 dB bandwidth of the antenna remained constant and equal to 12.5%, the maximum frequency shift occurred when the antenna was close to the elbow (6.61%) and on the thigh (5.86%). The smallest change was found on the torso (4.21%). Participants with body-mass index (BMI) between 17 and 29 kg/m 2 took part in experimental measurements, where the maximum frequency shift was 2.51%. Measurements showed better agreement with simulations on the upper arm. These experimental results demonstrate that the BMI for each individual had little effect on the performance of the antenna. Bioelectromagnetics. 39:25-34, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  4. High efficiency carbon nanotube thread antennas

    NASA Astrophysics Data System (ADS)

    Amram Bengio, E.; Senic, Damir; Taylor, Lauren W.; Tsentalovich, Dmitri E.; Chen, Peiyu; Holloway, Christopher L.; Babakhani, Aydin; Long, Christian J.; Novotny, David R.; Booth, James C.; Orloff, Nathan D.; Pasquali, Matteo

    2017-10-01

    Although previous research has explored the underlying theory of high-frequency behavior of carbon nanotubes (CNTs) and CNT bundles for antennas, there is a gap in the literature for direct experimental measurements of radiation efficiency. These measurements are crucial for any practical application of CNT materials in wireless communication. In this letter, we report a measurement technique to accurately characterize the radiation efficiency of λ/4 monopole antennas made from the CNT thread. We measure the highest absolute values of radiation efficiency for CNT antennas of any type, matching that of copper wire. To capture the weight savings, we propose a specific radiation efficiency metric and show that these CNT antennas exceed copper's performance by over an order of magnitude at 1 GHz and 2.4 GHz. We also report direct experimental observation that, contrary to metals, the radiation efficiency of the CNT thread improves significantly at higher frequencies. These results pave the way for practical applications of CNT thread antennas, particularly in the aerospace and wearable electronics industries where weight saving is a priority.

  5. A Novel Approach for a Low-Cost Deployable Antenna

    NASA Technical Reports Server (NTRS)

    Amend, Chris; Nurnberger, Michael; Oppenheimer, Paul; Koss, Steve; Purdy, Bill

    2010-01-01

    The Naval Research Laboratory (NRL) has designed, built, and fully qualified a low cost, low Passive Intermodulation (PIM) 12-foot (3.66-m) diameter deployable ultra high frequency (UHF) antenna for the Tacsat-4 program. The design utilized novel approaches in reflector material and capacitive coupling techniques. This paper discusses major design trades, unique design characteristics, and lessons learned from the development of the Tacsat 4 deployable antenna. This antenna development was sponsored by the Office of Naval Research.

  6. A Huygens Surface Approach to Antenna Implementation in Near-Field Radar Imaging System Simulations

    DTIC Science & Technology

    2015-08-01

    environment. The model consists of an ultra - wideband , forward-looking radar imaging system, equipped with a multi-static antenna array and mounted on a...of the receiving antenna. 2.2 Huygens Surface Implementation Details The NAFDTD code implements the excitation waveform as a short, ultra - wideband ...

  7. Astigmatism in reflector antennas.

    NASA Technical Reports Server (NTRS)

    Cogdell, J. R.; Davis, J. H.

    1973-01-01

    Astigmatic phase error in large parabolic reflector antennas is discussed. A procedure for focusing an antenna and diagnosing the presence and degree of astigmatism is described. Theoretical analysis is conducted to determine the nature of this error in such antennas.

  8. Radiation characteristics of input power from surface wave sustained plasma antenna

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Naito, T., E-mail: Naito.Teruki@bc.MitsubishiElectric.co.jp; Yamaura, S.; Fukuma, Y.

    This paper reports radiation characteristics of input power from a surface wave sustained plasma antenna investigated theoretically and experimentally, especially focusing on the power consumption balance between the plasma generation and the radiation. The plasma antenna is a dielectric tube filled with argon and small amount of mercury, and the structure is a basic quarter wavelength monopole antenna at 2.45 GHz. Microwave power at 2.45 GHz is supplied to the plasma antenna. The input power is partially consumed to sustain the plasma, and the remaining part is radiated as a signal. The relationship between the antenna gain and the input powermore » is obtained by an analytical derivation and numerical simulations. As a result, the antenna gain is kept at low values, and most of the input power is consumed to increase the plasma volume until the tube is filled with the plasma whose electron density is higher than the critical electron density required for sustaining the surface wave. On the other hand, the input power is consumed to increase the electron density after the tube is fully filled with the plasma, and the antenna gain increases with increasing the electron density. The dependence of the antenna gain on the electron density is the same as that of a plasma antenna sustained by a DC glow discharge. These results are confirmed by experimental results of the antenna gain and radiation patterns. The antenna gain of the plasma is a few dB smaller than that of the identical metal antenna. The antenna gain of the plasma antenna is sufficient for the wireless communication, although it is difficult to substitute the plasma antenna for metal antennas completely. The plasma antenna is suitable for applications having high affinity with the plasma characteristics such as low interference and dynamic controllability.« less

  9. ATCRBS Antenna Modification Kit

    DOT National Transportation Integrated Search

    1976-06-01

    The report describes the design, fabrication and test results of an improved ATCRBS (Air Traffic Control Radar Beacon System) array antenna for mounting on the reflector of an ASR radar antenna. The antenna consists of a 4-foot high by 26-foot wide a...

  10. RF Antenna Design for a Helicon Plasma Source

    NASA Astrophysics Data System (ADS)

    Godden, Katarina; Stassel, Brendan; Warta, Daniel; Yep, Isaac; Hicks, Nathaniel; Munk, Jens

    2017-10-01

    A helicon plasma source is under development for the new Plasma Science and Engineering Laboratory at the University of Alaska Anchorage. The helicon source is of a type comprising Pyrex and stainless steel cylindrical sections, joined to an ultrahigh vacuum chamber. A radio frequency (RF) helical antenna surrounds the Pyrex chamber, as well as DC solenoidal magnetic field coils. This presentation focuses on the design of the RF helical antenna and RF matching network, such that helicon wave power is coupled to argon plasma with minimal reflected power to the RF amplifier. The amplifier output is selectable between 2-30 MHz, with forward c.w. power up to 1.5 kW. Details and computer simulation of the antenna geometry, materials, and power matching will be presented, as well as the matching network of RF transmission line, tuning capacitors, and cooling system. An initial computational study of power coupling to the plasma will also be described. Supported by U.S. NSF/DOE Partnership in Basic Plasma Science and Engineering Grant PHY-1619615, by the Alaska Space Grant Program, and by UAA Innovate 2017.

  11. Antenna Efficiency and the Genius of the IEEE Standard for Antenna Terms [Education Column

    NASA Astrophysics Data System (ADS)

    Warnick, Karl F.

    2012-08-01

    At a 2007 Square Kilometre Array Design Studies (SKADS) workshop in Dwingeloo, Wim van Cappellen of the Nether lands Institute for Radio Astronomy (ASTRON) gave a presentation on figures of merit, in which he memorably compared antenna terms to apples. What seems like a simple, homogeneous fruit comes in all colors and varieties. Similarly, a survey of antenna literature and textbooks shows that authors use a wide variety of antenna figures of merit, often not in compliance with the relevant IEEE Standard Definitions of Terms for Antennas [1]. Since this standard is now in the process of revision by the Antennas and Propagation Society Antenna Standards Committee, it seems worth while to consider the standard, and clarify some common misunderstandings and inconsistent usages.

  12. Ion source with external RF antenna

    DOEpatents

    Leung, Ka-Ngo; Ji, Qing; Wilde, Stephen

    2005-12-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source.

  13. Far field focusing for a microwave patch antenna with composite substrate

    NASA Astrophysics Data System (ADS)

    Wan, Jian; Rybin, Oleg; Shulga, Sergey

    2018-03-01

    Modeling for a compact microwave antenna structure on base of a miniaturized rectangular patch antenna with composite substrate and magnetic superstrates is made in this study by using FDTD simulations. The resonant frequency of the antenna structure is supposed to be 15 GHz. The design of the antenna with composite substrate and without superstrate is made up by using the microwave miniaturization concept for rectangular patch antennas created by first author of this study. The optimal distance between the superstrate and antenna surface is found by using Fabry-Perot cavity theory as maximum values of power directivity and efficiency of the antenna is achieved. The comparative analysis with regard to some far and near field parameters of the above antenna structures and the antenna with dielectric substrate having same value of the relative permittivity is performed.

  14. 47 CFR 25.286 - Antenna painting and lighting.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Antenna painting and lighting. 25.286 Section... SATELLITE COMMUNICATIONS Technical Operations § 25.286 Antenna painting and lighting. The owner of an earth station antenna structure must comply with all applicable painting, marking, and/or lighting requirements...

  15. A Novel L-Probe Proximity Fed Patch Antenna With Parasitic Patch and Its Utilization in Antenna Arrays

    NASA Astrophysics Data System (ADS)

    Sláma, Libor; Dobeš, Josef; Boštík, Tomáš; Vejražka, František

    2018-03-01

    An analysis of the L-probe fed patch antenna with an extraordinary parasitic patch is described. The element of the antenna is fed by the L-probe partially implemented in PCB. An excellent impedance matching is obtained (< ‑26 dB in the design frequency band 4.4–5 GHz). The radiation characteristics are also very good (gain > 10 dBi). For the numerical analyses, the Full Wave—CST Microwave Studio software was used in both frequency and time domains, and a very good agreement between the Time Domain Solver (TDS) and Frequency Domain Solver (FDS) was obtained. Real antenna samples have been created and measured as well as eight-element antenna arrays designed by the Dolph-Chebyshev method.

  16. Spatial and temporal temperature distribution optimization for a geostationary antenna

    NASA Technical Reports Server (NTRS)

    Tsuyuki, G.; Miyake, R.

    1992-01-01

    The Geostationary Microwave Precipitation Radiometer antenna is considered and a thermal design analysis is performed to determine a design that would minimize on-orbit antenna temporal and spatial temperature gradients. The final design is based on an optically opaque radome which covered the antenna. The average orbital antenna temperature is found to be 9 C with maximum temporal and spatial variations of 34 C and 1 C, respectively. An independent thermal distortion analysis showed that this temporal variation would give an antenna figure error of 14 microns.

  17. Implantable multilayer microstrip antenna for retinal prosthesis: antenna testing.

    PubMed

    Permana, Hans; Fang, Qiang; Rowe, Wayne S T

    2012-01-01

    Retinal prosthesis has come to a more mature stage and become a very strategic answer to Retinitis Pigmentosa (RP) and Age-related Macular Degeneration (AMD) diseases. In a retinal prosthesis system, wireless link holds a great importance for the continuity of the system. In this paper, an implantable multilayer microstrip antenna was proposed for the retinal prosthesis system. Simulations were performed in High Frequency Structure Simulator (HFSS) with the surrounding material of air and Vitreous Humor fluid. The fabricated antenna was measured for characteristic validation in free space. The results showed that the real antenna possessed similar return loss and radiation pattern, while there was discrepancy with the gain values.

  18. Carbon Nanotube Thin-Film Antennas.

    PubMed

    Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

    2016-08-17

    Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of <10 ohm/sq is needed to achieve a 10 dB return loss in the unbalanced antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed.

  19. High Efficiency Carbon Nanotube Thread Antennas

    NASA Astrophysics Data System (ADS)

    Bengio, Elie; Senic, Damir; Taylor, Lauren; Tsentalovich, Dmitri; Chen, Peiyu; Holloway, Christopher; Novotny, David; Babakhani, Aydin; Long, Christopher; Booth, James; Orloff, Nathan; Pasquali, Matteo

    Although previous research has explored the underlying theory of high-frequency behavior of carbon nanotubes (CNTs) and CNT bundles for antennas, there is a gap in the literature for direct experimental measurements of radiation efficiency. Here we report a novel measurement technique to accurately characterize the radiation efficiency of quarter-wavelength monopole antennas made from CNT thread. At medical device (1 GHz) and Wi-Fi (2.4 GHz) frequencies, we measured the highest absolute values of radiation efficiency in the literature for CNT antennas, matching that of copper wire. We also report the first direct experimental observation that, contrary to metals, the radiation efficiency of the CNT thread improves significantly at higher frequencies. These results pave the way for practical applications of CNT thread antennas, particularly in the aerospace and wearable electronics industries where weight saving is a priority.

  20. Recent activities in printed Antennas at LeRC

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Simons, Rainee N.

    1993-01-01

    This paper will report two recent R&D efforts in printed antennas at NASA Lewis Research Center. These efforts are: (1) to enhance the current antenna performance in gain, bandwidth and pattern characteristics, and (2) to develop coplanar waveguide/aperture coupled feeding technique for dual excitation of a patch antenna. Research in area (1) has led to the development of a nonplanar linearly tapered slot antenna (LTSA) which has exhibited over 10 dB gain with broad bandwidth and excellent radiation patterns. This endfire antenna element is most suitable for use in MMIC arrays of 'brick' construction. A space power amplifier composed of active LTSA has been demonstrated and shown to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit (MMIC) three-stage power amplifier is integrated with two LTSA's. A single active LTSA has also been demonstrated and exhibited a power gain of 6.7 dB with the MMIC amplifier turned on. The aperture coupled feeding technique with coplanar waveguide feeds has demonstrated high coupling efficiency on both LTSA and patch antennas. Recent efforts have been focused on applying this technique for dual excitation (dual frequency and/or dual polarization) of a patch antenna. Preliminary results confirm the feasibility of this approach. Further development is required to improve the coupling efficiency and antenna radiation characteristics.

  1. 47 CFR 25.205 - Minimum angle of antenna elevation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Minimum angle of antenna elevation. 25.205... SATELLITE COMMUNICATIONS Technical Standards § 25.205 Minimum angle of antenna elevation. (a) Earth station antennas shall not normally be authorized for transmission at angles less than 5° measured from the...

  2. 47 CFR 25.205 - Minimum angle of antenna elevation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Minimum angle of antenna elevation. 25.205... SATELLITE COMMUNICATIONS Technical Standards § 25.205 Minimum angle of antenna elevation. (a) Earth station antennas shall not normally be authorized for transmission at angles less than 5° measured from the...

  3. 47 CFR 25.205 - Minimum angle of antenna elevation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Minimum angle of antenna elevation. 25.205... SATELLITE COMMUNICATIONS Technical Standards § 25.205 Minimum angle of antenna elevation. (a) Earth station antennas shall not normally be authorized for transmission at angles less than 5° measured from the...

  4. 47 CFR 25.205 - Minimum angle of antenna elevation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Minimum angle of antenna elevation. 25.205... SATELLITE COMMUNICATIONS Technical Standards § 25.205 Minimum angle of antenna elevation. (a) Earth station antennas shall not normally be authorized for transmission at angles less than 5° measured from the...

  5. Electrically Small Folded Slot Antenna Utilizing Capacitive Loaded Slot Lines

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Ponchak, George E.; Merritt, Shane; Minor, John S.; Zorman, Christian A.

    2007-01-01

    This paper presents an electrically small, coplanar waveguide fed, folded slot antenna that uses capacitive loading. Several antennas are fabricated with and without capacitive loading to demonstrate the ability of this design approach to reduce the resonant frequency of the antenna, which is analogous to reducing the antenna size. The antennas are fabricated on Cu-clad Rogers Duriod(TM) 6006 with multilayer chip capacitors to load the antennas. Simulated and measured results show close agreement, thus, validating the approach. The electrically small antennas have a measured return loss greater than 15 dB and a gain of 5.4, 5.6, and 2.7 dBi at 4.3, 3.95, and 3.65 GHz, respectively.

  6. A Minimized MIMO-UWB Antenna with High Isolation and Triple Band-Notched Functions

    NASA Astrophysics Data System (ADS)

    Kong, Yuanyuan; Li, Yingsong; Yu, Kai

    2016-11-01

    A compact high isolation MIMO-UWB antenna with triple frequency rejection bands is proposed for UWB communication applications. The proposed MIMO-UWB antenna consists of two identical UWB antennas and each antenna element has a semicircle ring shaped radiation patch fed by a bend microstrip feeding line for covering the UWB band, which operates from 2.85 GHz to 11.79 GHz with an impedance bandwidth of 122.1 %. By etching a L-shaped slot on the ground plane, and embedding an "anchor" shaped stub into the patch and integrating an open ring under the semicircle shaped radiation patch, three notch bands are realized to suppress WiMAX (3.3-3.6 GHz), WLAN(5.725-5.825 GHz) and uplink of X-band satellite (7.9-8.4 GHz) signals. The high isolation with S21<-20 dB in most UWB band is obtained by adding a protruded decoupling structure. The design procedure of the MIMO-UWB antenna is given in detail. The proposed MIMO-UWB antenna is simulated, fabricated and measured. Experimental results demonstrate that the proposed MIMO-UWB antenna has a stable gain, good impedance match, high isolation, low envelope correlation coefficient and good radiation pattern at the UWB operating band and it can provide three designated notch bands.

  7. Small Patch Antennas for UWB Wireless Body Area Network

    NASA Astrophysics Data System (ADS)

    Klemm, M.; Tröster, G.

    This paper presents the transient characteristics of an aperture-stacked patch antenna (ASPA) and its miniaturized version. These antennas were designed for ultra-wideband (UWB) body area network (BAN) applications, to operate within the 3 to 6 GHz frequency band. The APSA with large ground plane size has a planar dimensions 70 × 70 mm2, the smaller version has dimensions 32 × 26 mm2. The latest yields 85% reduction of the antenna surface. Time- and frequency-domain characteristics of these antennas were calculated in a transmission mode (Tx) and also in a complete, two-antenna (Tx-Rx) system. We have used 3 different waveforms to drive the antenna: gaussian pulse (duration-250 ps), monocycle pulse (duration-300 ps) and defined wavelet (duration-650 ps). The received pulses have very similar shapes (fidelity >90%), but they differ in the voltage amplitudes. Results show that the highest received voltage (best transmission efficiency) is achieved for the pulse with the closest spectrum to the antenna's transfer function characteristic. In order to disclose the effects of the human body proximity, two body models were built and full-wave FDTD method was employed to carry out the simulations. Significant changes of the UWB antenna performance when close to the body were identified. The most important effects are the seriously decreased radiation efficiency (16 to 34%) and different (from that in a free space) shape of the antenna transfer function. The first one can have the impact on low power implementations of UWB wearable radios; the second one discloses possible influence on the UWB systems design (especially for template receivers). The impact of the human body on antenna characteristics was identified to be a key factor in UWB body-worn antenna design.

  8. DIRECTIONAL ANTENNA

    DOEpatents

    Bittner, B.J.

    1958-05-20

    A high-frequency directional antenna of the 360 d scaring type is described. The antenna has for its desirable features the reduction in both size and complexity of the mechanism for rotating the antenna through its scanning movement. These advantages result from the rotation of only the driven element, the reflector remaining stationary. The particular antenna structure comprises a refiector formed by a plurality of metallic slats arranged in the configuration of an annular cage having the shape of a zone of revolution. The slats are parallel to each other and are disposed at an angle of 45 d to the axis of the cage. A directional radiator is disposed inside the cage at an angle of 45 d to the axis of the cage in the same direction as the reflecting slats which it faces. As the radiator is rotated, the electromagnetic wave is reflected from the slats facing the radiator and thereafter passes through the cage on the opposite side, since these slats are not parallel with the E vector of the wave.

  9. Characteristics of the wire biconical antenna used for EMC measurements

    NASA Astrophysics Data System (ADS)

    Austin, Brian A.; Fourie, Andre P. C.

    1991-08-01

    The characteristics of a wire biconical antenna that determine its antenna factor were computed by using the method of moments code NEC-2. A fairly extensive validation exercise was conducted from which a suitable computer model was derived. The input impedance, gain, and radiation patterns of the antenna were computed for special cases where the biconical antenna is used above a conducting ground plane for open-field EMC (electromagnetic compatibility) testing. The effects of height above the ground plane and polarization of the antenna on these parameters were found and the antenna factor was corrected for them. The current distribution along the antenna elements was also examined, and it was found that significant pattern distortion can occur at some frequencies when a horizontal wire biconical antenna is used close to the ground. These results will allow this broadband antenna to be used with confidence in applications where previously only resonant dipoles were specified.

  10. A wideband spiral antenna for ingestible capsule endoscope systems: experimental results in a human phantom and a pig.

    PubMed

    Lee, Sang Heun; Lee, Jaebok; Yoon, Young Joong; Park, Sangbok; Cheon, Changyul; Kim, Kihyun; Nam, Sangwook

    2011-06-01

    This paper presents the design of a wideband spiral antenna for ingestible capsule endoscope systems and a comparison between the experimental results in a human phantom and a pig under general anesthesia. As wireless capsule endoscope systems transmit real-time internal biological image data at a high resolution to external receivers and because they operate in the human body, a small wideband antenna is required. To incorporate these properties, a thick-arm spiral structure is applied to the designed antenna. To make practical and efficient use of antennas inside the human body, which is composed of a high dielectric and lossy material, the resonance characteristics and radiation patterns were evaluated through a measurement setup using a liquid human phantom. The total height of the designed antenna is 5 mm and the diameter is 10 mm. The fractional bandwidth of the fabricated antenna is about 21% with a voltage standing-wave ratio of less than 2, and it has an isotropic radiation pattern. These characteristics are suitable for wideband capsule endoscope systems. Moreover, the received power level was measured using the proposed antenna, a circular polarized receiver antenna, and a pig under general anesthesia. Finally, endoscopic capsule images in the stomach and large intestine were captured using an on-off keying transceiver system.

  11. 47 CFR 80.866 - Spare antenna.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Spare antenna. 80.866 Section 80.866... Spare antenna. A spare transmitting antenna completely assembled for immediate erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be a...

  12. 47 CFR 80.866 - Spare antenna.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Spare antenna. 80.866 Section 80.866... Spare antenna. A spare transmitting antenna completely assembled for immediate erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be a...

  13. 47 CFR 80.866 - Spare antenna.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Spare antenna. 80.866 Section 80.866... Spare antenna. A spare transmitting antenna completely assembled for immediate erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be a...

  14. 47 CFR 80.866 - Spare antenna.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Spare antenna. 80.866 Section 80.866... Spare antenna. A spare transmitting antenna completely assembled for immediate erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be a...

  15. 47 CFR 80.866 - Spare antenna.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Spare antenna. 80.866 Section 80.866... Spare antenna. A spare transmitting antenna completely assembled for immediate erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be a...

  16. 47 CFR 24.132 - Power and antenna height limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Power and antenna height limits. 24.132 Section... PERSONAL COMMUNICATIONS SERVICES Narrowband PCS § 24.132 Power and antenna height limits. (a) Stations... unlimited in antenna height except as provided in paragraph (d) of this section. (d)(1) MTA and regional...

  17. 47 CFR 24.132 - Power and antenna height limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Power and antenna height limits. 24.132 Section... PERSONAL COMMUNICATIONS SERVICES Narrowband PCS § 24.132 Power and antenna height limits. (a) Stations... unlimited in antenna height except as provided in paragraph (d) of this section. (d)(1) MTA and regional...

  18. 47 CFR 24.132 - Power and antenna height limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Power and antenna height limits. 24.132 Section... PERSONAL COMMUNICATIONS SERVICES Narrowband PCS § 24.132 Power and antenna height limits. (a) Stations... unlimited in antenna height except as provided in paragraph (d) of this section. (d)(1) MTA and regional...

  19. 47 CFR 24.132 - Power and antenna height limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Power and antenna height limits. 24.132 Section... PERSONAL COMMUNICATIONS SERVICES Narrowband PCS § 24.132 Power and antenna height limits. (a) Stations... unlimited in antenna height except as provided in paragraph (d) of this section. (d)(1) MTA and regional...

  20. 47 CFR 24.132 - Power and antenna height limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Power and antenna height limits. 24.132 Section... PERSONAL COMMUNICATIONS SERVICES Narrowband PCS § 24.132 Power and antenna height limits. (a) Stations... unlimited in antenna height except as provided in paragraph (d) of this section. (d)(1) MTA and regional...

  1. 47 CFR 95.1013 - Antennas.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Antennas. 95.1013 Section 95.1013... SERVICES Low Power Radio Service (LPRS) General Provisions § 95.1013 Antennas. (a) The maximum allowable... this chapter, at the band edges. (b) AMTS stations must employ directional antennas. (c) Antennas used...

  2. 47 CFR 95.1213 - Antennas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Antennas. 95.1213 Section 95.1213... SERVICES Medical Device Radiocommunication Service (MedRadio) § 95.1213 Antennas. No antenna for a MedRadio transmitter shall be configured for permanent outdoor use. In addition, any MedRadio antenna used outdoors...

  3. 47 CFR 95.1013 - Antennas.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Antennas. 95.1013 Section 95.1013... SERVICES Low Power Radio Service (LPRS) General Provisions § 95.1013 Antennas. (a) The maximum allowable... this chapter, at the band edges. (b) AMTS stations must employ directional antennas. (c) Antennas used...

  4. 47 CFR 95.1213 - Antennas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antennas. 95.1213 Section 95.1213... SERVICES Medical Device Radiocommunication Service (MedRadio) § 95.1213 Antennas. No antenna for a MedRadio transmitter shall be configured for permanent outdoor use. In addition, any MedRadio antenna used outdoors...

  5. 47 CFR 95.1013 - Antennas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Antennas. 95.1013 Section 95.1013... SERVICES Low Power Radio Service (LPRS) General Provisions § 95.1013 Antennas. (a) The maximum allowable... this chapter, at the band edges. (b) AMTS stations must employ directional antennas. (c) Antennas used...

  6. 47 CFR 95.1013 - Antennas.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Antennas. 95.1013 Section 95.1013... SERVICES Low Power Radio Service (LPRS) General Provisions § 95.1013 Antennas. (a) The maximum allowable... this chapter, at the band edges. (b) AMTS stations must employ directional antennas. (c) Antennas used...

  7. 47 CFR 95.1013 - Antennas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antennas. 95.1013 Section 95.1013... SERVICES Low Power Radio Service (LPRS) General Provisions § 95.1013 Antennas. (a) The maximum allowable... this chapter, at the band edges. (b) AMTS stations must employ directional antennas. (c) Antennas used...

  8. E-Textile Antennas for Space Environments

    NASA Technical Reports Server (NTRS)

    Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.

    2007-01-01

    The ability to integrate antennas and other radio frequency (RF) devices into wearable systems is increasingly important as wireless voice, video, and data sources become ubiquitous. Consumer applications including mobile computing, communications, and entertainment, as well as military and space applications for integration of biotelemetry, detailed tracking information and status of handheld tools, devices and on-body inventories are driving forces for research into wearable antennas and other e-textile devices. Operational conditions for military and space applications of wireless systems are often such that antennas are a limiting factor in wireless performance. The changing antenna platform, i.e. the dynamic wearer, can detune and alter the radiation characteristics of e-textile antennas, making antenna element selection and design challenging. Antenna designs and systems that offer moderate bandwidth, perform well with flexure, and are electronically reconfigurable are ideally suited to wearable applications. Several antennas, shown in Figure 1, have been created using a NASA-developed process for e-textiles that show promise in being integrated into a robust wireless system for space-based applications. Preliminary characterization of the antennas with flexure indicates that antenna performance can be maintained, and that a combination of antenna design and placement are useful in creating robust designs. Additionally, through utilization of modern smart antenna techniques, even greater flexibility can be achieved since antenna performance can be adjusted in real-time to compensate for the antenna s changing environment.

  9. A Dual Band Frequency Reconfigurable Origami Magic Cube Antenna for Wireless Sensor Network Applications

    PubMed Central

    Shah, Syed Imran Hussain

    2017-01-01

    In this paper, a novel dual band frequency reconfigurable antenna using an origami magic cube is proposed for wireless sensor network (WSN) applications. The proposed origami antenna consists of a meandered monopole folded onto three sides of the magic cube. A microstrip open-ended stub is loaded on the meandered monopole. The proposed origami magic cube can be mechanically folded and unfolded. The proposed antenna operates at 1.57 GHZ and 2.4 GHz in the folded state. In the unfolded state, the proposed antenna operates at 900 MHz and 2.3 GHz. The resonant frequency of the second band can be tunable by varying the length and position of the open stub. The origami magic cube is built on paper. Its performance is numerically and experimentally demonstrated from S-parameters and radiation patterns. The measured 10 dB impedance bandwidth of the proposed origami antenna is 18% (900–1120 MHz) and 15% (2.1–2.45 GHz) for the unfolded state and 20% (1.3–1.6 GHz) and 14% (2.3–2.5 GHz) for the folded state. The measured peak gain at 900 MHz and 2.3 GHz are 1.1 dBi and 2.32 dBi, respectively, in the unfolded state. The measured peak gain at 1.5 GHz and 2.4 GHz are 3.28 dBi and 1.98 dBi, respectively, in the folded state. PMID:29156654

  10. A Dual Band Frequency Reconfigurable Origami Magic Cube Antenna for Wireless Sensor Network Applications.

    PubMed

    Shah, Syed Imran Hussain; Lim, Sungjoon

    2017-11-20

    In this paper, a novel dual band frequency reconfigurable antenna using an origami magic cube is proposed for wireless sensor network (WSN) applications. The proposed origami antenna consists of a meandered monopole folded onto three sides of the magic cube. A microstrip open-ended stub is loaded on the meandered monopole. The proposed origami magic cube can be mechanically folded and unfolded. The proposed antenna operates at 1.57 GHZ and 2.4 GHz in the folded state. In the unfolded state, the proposed antenna operates at 900 MHz and 2.3 GHz. The resonant frequency of the second band can be tunable by varying the length and position of the open stub. The origami magic cube is built on paper. Its performance is numerically and experimentally demonstrated from S-parameters and radiation patterns. The measured 10 dB impedance bandwidth of the proposed origami antenna is 18% (900-1120 MHz) and 15% (2.1-2.45 GHz) for the unfolded state and 20% (1.3-1.6 GHz) and 14% (2.3-2.5 GHz) for the folded state. The measured peak gain at 900 MHz and 2.3 GHz are 1.1 dBi and 2.32 dBi, respectively, in the unfolded state. The measured peak gain at 1.5 GHz and 2.4 GHz are 3.28 dBi and 1.98 dBi, respectively, in the folded state.

  11. Broadband Ground Penetrating Radar with conformal antennas for subsurface imaging from a rover

    NASA Astrophysics Data System (ADS)

    Stillman, D. E.; Oden, C. P.; Grimm, R. E.; Ragusa, M.

    2015-12-01

    Ground-Penetrating Radar (GPR) allows subsurface imaging to provide geologic context and will be flown on the next two martian rovers (WISDOM on ExoMars and RIMFAX on Mars 2020). The motivation of our research is to minimize the engineering challenges of mounting a GPR antenna to a spacecraft, while maximizing the scientific capabilities of the GPR. The scientific capabilities increase with the bandwidth as it controls the resolution. Furthermore, ultra-wide bandwidth surveys allow certain mineralogies and rock units to be discriminated based on their frequency-dependent EM or scattering properties. We have designed and field-tested a prototype GPR that utilizes bi-static circularly polarized spiral antennas. Each antenna has a physical size of 61 x 61 x 4 cm, therefore two antennas could be mounted to the underbelly of a MSL-class rover. Spiral antennas were chosen because they have an inherent broadband response and provide a better low frequency response compared with similarly sized linearly polarized antennas. A horizontal spiral radiator emits energy both upward and downward directions. After the radiator is mounted to a metal surface (i.e. the underside of a rover), a cavity is formed that causes the upward traveling energy to reverberate and cause unwanted interference. This interference is minimized by 1) using a high metallization ratio on the spiral to reduce cavity emissions, and 2) placing absorbing material inside the cavity. The resulting antennas provide high gain (0 to 8 dBi) from 200 to 1000 MHz. The low frequency response can be improved by increasing the antenna thickness (i.e., cavity depth). In an initial field test, the antennas were combined with impulse GPR electronics that had ~140 dB of dynamic range (not including antennas) and a sand/clay interface 7 feet deep was detected. To utilize the full bandwidth the antennas, a gated Frequency Modulated Continuous Waveform system will be developed - similar to RIMFAX. The goal is to reach a

  12. Design and fabrication of a microstrip patch antenna with a low radar cross section in the X-band

    NASA Astrophysics Data System (ADS)

    Jang, Hong-Kyu; Lee, Won-Jun; Kim, Chun-Gon

    2011-01-01

    In this study, the authors developed a radar absorbing method to reduce the antenna radar cross section (RCS) without any loss of antenna performance. The new method was based upon an electromagnetic bandgap (EBG) absorber using conducting polymer (CP). First, a microstrip patch antenna was made by using a copper film and glass/epoxy composite materials, which are typically used for load-bearing structures, such as aircraft and other vehicles. Then, CP EBG patterns were also designed that had a 90% electromagnetic (EM) wave absorbing performance within the X-band (8.2-12.4 GHz). Finally, the CP EBG patterns were printed on the top surface of the microstrip patch antenna. The measured radar absorbing performance of the fabricated patch antenna showed that the frontal RCS of the antenna declined by nearly 95% at 10 GHz frequency while the CP EBG patterns had almost no effect on the antenna's performance.

  13. Probe-fed semi circular microstrip antenna vis-à-vis circular microstrip antenna: a necessary revisit

    NASA Astrophysics Data System (ADS)

    Ghosh, S. K.; Varshney, S. K.; Chakraborty, S.; Singh, L. L. K.; Chattopadhyay, S.

    2018-03-01

    Microstrip patch antenna of semicircular geometry has been investigated in view of miniaturization of conventional circular geometry. The precise operating frequency of the semicircular microstrip patch antenna is the most significant parameter to be determined in order to design such antenna system to achieve the optimum performance. In the present investigation an improved formulation is presented for accurate determination of the resonant frequency of semicircular patch. Also, the radiation property of such patch is thoroughly investigated. Through comparisons are documented amongst the circular and semicircular patches. It is revealed that, the semicircular patch offers more better radiation performance compared to circular.

  14. 47 CFR 24.232 - Power and antenna height limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Power and antenna height limits. 24.232 Section... PERSONAL COMMUNICATIONS SERVICES Broadband PCS § 24.232 Power and antenna height limits. (a)(1) Base... radiated power (EIRP) with an antenna height up to 300 meters HAAT, except as described in paragraph (b...

  15. 47 CFR 24.232 - Power and antenna height limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Power and antenna height limits. 24.232 Section... PERSONAL COMMUNICATIONS SERVICES Broadband PCS § 24.232 Power and antenna height limits. (a)(1) Base... radiated power (EIRP) with an antenna height up to 300 meters HAAT, except as described in paragraph (b...

  16. 47 CFR 24.232 - Power and antenna height limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Power and antenna height limits. 24.232 Section... PERSONAL COMMUNICATIONS SERVICES Broadband PCS § 24.232 Power and antenna height limits. (a)(1) Base... radiated power (EIRP) with an antenna height up to 300 meters HAAT, except as described in paragraph (b...

  17. 47 CFR 24.232 - Power and antenna height limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Power and antenna height limits. 24.232 Section... PERSONAL COMMUNICATIONS SERVICES Broadband PCS § 24.232 Power and antenna height limits. (a)(1) Base... radiated power (EIRP) with an antenna height up to 300 meters HAAT, except as described in paragraph (b...

  18. 47 CFR 24.232 - Power and antenna height limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Power and antenna height limits. 24.232 Section... PERSONAL COMMUNICATIONS SERVICES Broadband PCS § 24.232 Power and antenna height limits. (a)(1) Base... radiated power (EIRP) with an antenna height up to 300 meters HAAT, except as described in paragraph (b...

  19. 47 CFR 73.69 - Antenna monitors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Antenna monitors. 73.69 Section 73.69... Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the transmitter site an FCC authorized antenna monitor. (b) In the event that the antenna...

  20. 47 CFR 73.69 - Antenna monitors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Antenna monitors. 73.69 Section 73.69... Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the transmitter site an FCC authorized antenna monitor. (b) In the event that the antenna...

  1. 47 CFR 73.69 - Antenna monitors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Antenna monitors. 73.69 Section 73.69... Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the transmitter site an FCC authorized antenna monitor. (b) In the event that the antenna...

  2. 47 CFR 73.69 - Antenna monitors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna monitors. 73.69 Section 73.69... Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the transmitter site an FCC authorized antenna monitor. (b) In the event that the antenna...

  3. 47 CFR 73.69 - Antenna monitors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Antenna monitors. 73.69 Section 73.69... Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the transmitter site an FCC authorized antenna monitor. (b) In the event that the antenna...

  4. Spacecraft Doppler tracking with a VLBI antenna

    NASA Technical Reports Server (NTRS)

    Comoretto, G.; Iess, L.; Bertotti, B.; Brenkle, J. P.; Horton, T.

    1990-01-01

    Preliminary results are reported from Doppler-shift measurements to the Voyager-2 spacecraft at a distance of 26 AU, obtained using the 32-m VLBI antenna at Medicina (Italy) during July and August 1988. The apparatus comprises the el-az antenna, an S-X-band receiver, a hydrogen maser to generate the reference signal, a Mark III VLBI terminal, and a digital tone extractor capable of isolating a tone of known frequency from a noisy signal and giving its phase and amplitude. A signal transmitted in S-band from the NASA Deep Space Network (DSN) station in Australia and retransmitted coherently in X-band by Voyager, was received 7 h 6 min later at Medicina and at the DSN station in Madrid. Sample data are presented graphically and shown to be of generally high quality; further in-depth analysis is under way.

  5. Dual Band Metamaterial Antenna For LTE/Bluetooth/WiMAX System.

    PubMed

    Hasan, Md Mehedi; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

    2018-01-19

    A compact metamaterial inspired antenna operate at LTE, Bluetooth and WiMAX frequency band is introduced in this paper. For the lower band, the design utilizes an outer square metallic strip forcing the patch to radiate as an equivalent magnetic-current loop. For the upper band, another magnetic current loop is created by adding metamaterial structure near the feed line on the patch. The metamaterial inspired antenna dimension of 42 × 32 mm 2 compatible to wireless devices. Finite integration technique based CST Microwave Studio simulator has been used to design and numerical investigation as well as lumped circuit model of the metamaterial antenna is explained with proper mathematical derivation. The achieved measured dual band operation of the conventional antenna are sequentially, 0.561~0.578 GHz, 2.346~2.906 GHz, and 2.91~3.49 GHz, whereas the metamaterial inspired antenna shows dual-band operation from 0.60~0.64 GHz, 2.67~3.40 GHz and 3.61~3.67 GHz, respectively. Therefore, the metamaterial antenna is applicable for LTE and WiMAX applications. Besides, the measured metamaterial antenna gains of 0.15~3.81 dBi and 3.47~3.75 dBi, respectively for the frequency band of 2.67~3.40 GHz and 3.61~3.67 GHz.

  6. A UHF RFID system with on-chip-antenna tag for short range communication

    NASA Astrophysics Data System (ADS)

    Qi, Peng; Chun, Zhang; Xijin, Zhao; Zhihua, Wang

    2015-05-01

    A UHF RF identification system based on the 0.18 μm CMOS process has been developed for short range and harsh size requirement applications, which is composed of a fully integrated tag and a special reader. The whole tag chip with the antenna takes up an area of 0.36 mm2, which is smaller than other reported tags with an on-chip antenna (OCA) using the standard CMOS process. A self-defined protocol is proposed to reduce the power consumption, and minimize the size of the tag. The specialized SOC reader system consists of the RF transceiver, digital baseband, MCU and host interface. Its power consumption is about 500 mW. Measurement results show that the system's reading range is 2 mm with 20 dBm reader output power. With an inductive antenna printed on a paper substrate around the OCA tag, the reading range can be extended from several centimeters to meters, depending on the shape and size of the inductive antenna.

  7. Geodetic antenna calibration test in the Antarctic environment

    USGS Publications Warehouse

    Grejner-Brzezinska, A.; Vazquez, E.; Hothem, L.

    2006-01-01

    TransAntarctic Mountain DEFormation (TAMDEF) Monitoring Network is the NSF-sponsored OSU and USGS project, aimed at measuring crustal motion in the Transantarctic Mountains of Victoria Land using GPS carrier phase measurements. Station monumentation, antenna mounts, antenna types, and data processing strategies were optimized to achieve mm-level estimates for the rates of motion. These data contributes also to regional Antarctic frame definition. Significant amount of data collected over several years allow the investigation of unique aspects of GPS geodesy in Antarctica, to determine how the error spectrum compares to the mid-latitude regions, and to identify the optimum measurement and data processing schemes for Antarctic conditions, in order to test the predicted rates of motion (mm-level w.r.t. time). The data collection for the TAMDEF project was initiated in 1996. The primary antenna used has been the Ashtech L1/L2 Dorne Margolin (D/M) choke ring. A few occupations involved the use of a Trimble D/M choke ring. The data were processed using the antenna calibration data available from the National Geodetic Survey (NGS). The recent developments in new antenna designs that are lighter in weight and lower in cost are being considered as a possible alternative to the bulkier and more expensive D/M choke ring design. In November 2003, in situ testing of three alternative models of L1/L2 antennas was conducted at a site located in the vicinity of McMurdo Station, Antarctica (S77.87, E166.56). The antenna models used in this test were: Ashtech D/M choke ring, Trimble D/M choke ring, Trimble Zephyr, and the NovAtel GPS-702. Two stations, spaced within 30 meters, were used in the test. Both had the characteristics similar to the stations of the TAMDEF network, i.e., the UNAVCO fixed-height, force-centered level mounts with a constant antenna offset were used, ensuring extreme stability of the antenna/ mount/pin set up. During each of the four 3-day test data collection

  8. Multifrequency synthetic aperture radar antenna comparison study. [for remote sensing

    NASA Technical Reports Server (NTRS)

    Blevins, B. A.

    1983-01-01

    Three multifrequency, dual polarization SAR antenna designs are reviewed. The SAR antenna design specifications were for a "straw man' SAR which would approximate the requirements for projected shuttle-based SAR's. Therefore, the physical dimensions were constrained to be compatible with the space shuttle. The electrical specifications were similar to those of SIR-A and SIR-B with the addition of dual polarization and the addition of C and X band operation. Early in the antenna design considerations, three candidate technologies emerged as having promise. They were: (1) microstrip patch planar array antennas, (2) slotted waveguide planar array antennas, and (3) open-ended waveguide planar array antennas.

  9. Microwave ablation of ex vivo bovine tissues using a dual slot antenna with a floating metallic sleeve.

    PubMed

    Ibitoye, Ayo Zaccheaus; Nwoye, Ephraim Okeke; Aweda, Adebayo Moses; Oremosu, Ademola A; Anunobi, Chidozie Charles; Akanmu, Nurudeen Olanrewaju

    2016-12-01

    To study the efficiency of a dual slot antenna with a floating metallic sleeve on the ablation of different ex vivo bovine tissues. COMSOL Multiphysics® version 4.4 (Stockholm, Sweden), which is based on finite element methods (FEM), was used to design and simulate monopole and dual slot with sleeve antennas. Power, specific absorption rate (SAR), temperature and necrosis distributions in the selected tissues were determined using these antennas. Monopole and dual slot with sleeve antennas were designed, simulated, constructed and applied in this study based on a semi-rigid coaxial cable. Ex vivo experiments were performed on liver, lung, muscle and heart of bovine obtained from a public animal slaughter house. The microwave energy was delivered using a 2.45 GHz solid-state microwave generator at 40 W for 3, 5 and 10 min. Aspect ratio, ablation length and ablation diameter were also determined on ablated tissues and compared with simulated results. Student's t-test was used to compare the statistically significant difference between the performance of the two antennas. The dual slot antenna with sleeve produces localised microwave energy better than the monopole antenna in all ablated tissues using simulation and experimental validation methods. There were significant differences in ablation diameter and aspect ratio between the sleeve antenna and monopole antenna. Additionally, there were no significant differences between the simulation and experimental results. This study demonstrated that the dual slot antenna with sleeve produced larger ablation zones and higher sphericity index in ex vivo bovine tissues with minimal backward heating when compared with the monopole antenna.

  10. 47 CFR 25.132 - Verification of earth station antenna performance standards.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Verification of earth station antenna... Verification of earth station antenna performance standards. (a)(1) All applications for transmitting earth... pursuant to § 2.902 of this chapter from the manufacturer of each antenna that the results of a series of...

  11. 47 CFR 25.132 - Verification of earth station antenna performance standards.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Verification of earth station antenna... Verification of earth station antenna performance standards. (a)(1) All applications for transmitting earth... pursuant to § 2.902 of this chapter from the manufacturer of each antenna that the results of a series of...

  12. 47 CFR 25.132 - Verification of earth station antenna performance standards.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Verification of earth station antenna... Verification of earth station antenna performance standards. (a)(1) All applications for transmitting earth... pursuant to § 2.902 of this chapter from the manufacturer of each antenna that the results of a series of...

  13. Design of a novel high efficiency antenna for helicon plasma sources

    NASA Astrophysics Data System (ADS)

    Fazelpour, S.; Chakhmachi, A.; Iraji, D.

    2018-06-01

    A new configuration for an antenna, which increases the absorption power and plasma density, is proposed for helicon plasma sources. The influence of the electromagnetic wave pattern symmetry on the plasma density and absorption power in a helicon plasma source with a common antenna (Nagoya) is analysed by using the standard COMSOL Multiphysics 5.3 software. In contrast to the theoretical model prediction, the electromagnetic wave does not represent a symmetric pattern for the common Nagoya antenna. In this work, a new configuration for an antenna is proposed which refines the asymmetries of the wave pattern in helicon plasma sources. The plasma parameters such as plasma density and absorption rate for a common Nagoya antenna and our proposed antenna under the same conditions are studied using simulations. In addition, the plasma density of seven operational helicon plasma source devices, having a common Nagoya antenna, is compared with the simulation results of our proposed antenna and the common Nagoya antenna. The simulation results show that the density of the plasma, which is produced by using our proposed antenna, is approximately twice in comparison to the plasma density produced by using the common Nagoya antenna. In fact, the simulation results indicate that the electric and magnetic fields symmetry of the helicon wave plays a vital role in increasing wave-particle coupling. As a result, wave-particle energy exchange and the plasma density of helicon plasma sources will be increased.

  14. The 64 meter antenna operation at K sub A band

    NASA Technical Reports Server (NTRS)

    Potter, P. D.

    1980-01-01

    The future potential of the 32 GHz K sub A band frequency region to planetary exploration, and the expected performance of the 64 m antenna network at 32 GHz is addressed. A modest level of noninterference upgrade work is assumed to achieve reasonable antenna aperture efficiency and alleviate antenna pointing difficulties. Electronic compensation of antenna aperture phasing errors is briefly considered as an alternative to the physical upgrade.

  15. A survey of ATL-compatible radiometer antennas

    NASA Technical Reports Server (NTRS)

    Love, A. W.

    1975-01-01

    A survey was made of antennas suitable for remote sensing of the earth's surface, in particular the world ocean, by means of microwave radiometers operating in the 1 to 26 GHz frequency region and carried on board the shuttle-launched advanced technology laboratory. Array antennas are found to be unattractive and unsuited to the task. Reflectors, including Cassegrain and offset types, as well as horn-reflectors are possible candidates but all have shortcomings which impair the accuracy of measurement. Horns of the corrugated type have excellent electrical characteristics. Although they are physically very large and will require development of suitable deployment mechanisms, they appear to be valid candidates for the task. The evolution of the periscope antenna is outlined, and it is shown to possess nearly ideal electrical characteristics for the intended application. Its only shortcoming is that the feed horn creates aperture blocking; there is no blocking due to struts or any other source. The periscope antenna is recommended for ATL radiometry.

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

    PubMed

    Curto, Sergio; Prakash, Punit

    2015-01-01

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

  17. 47 CFR 73.211 - Power and antenna height requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Power and antenna height requirements. 73.211... RADIO BROADCAST SERVICES FM Broadcast Stations § 73.211 Power and antenna height requirements. (a... Class C and C0 stations is 100 kW. (2) Class C0 stations must have an antenna height above average...

  18. 47 CFR 73.211 - Power and antenna height requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Power and antenna height requirements. 73.211... RADIO BROADCAST SERVICES FM Broadcast Stations § 73.211 Power and antenna height requirements. (a... Class C and C0 stations is 100 kW. (2) Class C0 stations must have an antenna height above average...

  19. 47 CFR 73.211 - Power and antenna height requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Power and antenna height requirements. 73.211... RADIO BROADCAST SERVICES FM Broadcast Stations § 73.211 Power and antenna height requirements. (a... Class C and C0 stations is 100 kW. (2) Class C0 stations must have an antenna height above average...

  20. 47 CFR 73.211 - Power and antenna height requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Power and antenna height requirements. 73.211... RADIO BROADCAST SERVICES FM Broadcast Stations § 73.211 Power and antenna height requirements. (a... Class C and C0 stations is 100 kW. (2) Class C0 stations must have an antenna height above average...

  1. 47 CFR 73.211 - Power and antenna height requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Power and antenna height requirements. 73.211... RADIO BROADCAST SERVICES FM Broadcast Stations § 73.211 Power and antenna height requirements. (a... Class C and C0 stations is 100 kW. (2) Class C0 stations must have an antenna height above average...

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

    DTIC Science & Technology

    1992-12-01

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

  3. Autonomous omnidirectional spacecraft antenna system

    NASA Technical Reports Server (NTRS)

    Taylor, T. H.

    1983-01-01

    The development of a low gain Electronically Switchable Spherical Array Antenna is discussed. This antenna provides roughly 7 dBic gain for receive/transmit operation between user satellites and the Tracking and Data Relay Satellite System. When used as a pair, the antenna provides spherical coverage. The antenna was tested in its primary operating modes: directed beam, retrodirective, and Omnidirectional.

  4. Spiral microstrip antenna with resistance

    NASA Technical Reports Server (NTRS)

    Shively, David G. (Inventor)

    1994-01-01

    The present invention relates to microstrip antennas, and more particularly to wide bandwidth spiral antennas with resistive loading. A spiral microstrip antenna having resistor element embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter of an inch. A square spiral, having either two or four arms, is attached to the dielectric slab. Each arm of the spiral has resistor elements thereby dissipating an excess energy not already emitted through radiation. The entire configuration provides a thin, flat, high gain, wide bandwidth antenna which requires no underlying cavity. The configuration allows the antenna to be mounted conformably on an aircraft surface.

  5. Multi-mode horn antenna simulation

    NASA Technical Reports Server (NTRS)

    Dod, L. R.; Wolf, J. D.

    1980-01-01

    Radiation patterns were computed for a circular multimode horn antenna using waveguide electric field radiation expressions. The circular multimode horn was considered as a possible reflector feed antenna for the Large Antenna Multifrequency Microwave Radiometer (LAMMR). This horn antenna uses a summation of the TE sub 11 deg and TM sub 11 deg modes to generate far field primary radiation patterns with equal E and H plane beamwidths and low sidelobes. A computer program for the radiation field expressions using the summation of waveguide radiation modes is described. The sensitivity of the multimode horn antenna radiation patterns to phase variations between the two modes is given. Sample radiation pattern calculations for a reflector feed horn for LAMMR are shown. The multimode horn antenna provides a low noise feed suitable for radiometric applications.

  6. Unidirectional Magneto-Electric Dipole Antenna for Base Station: A Review

    NASA Astrophysics Data System (ADS)

    Idayachandran, Govindanarayanan; Nakkeeran, Rangaswamy

    2018-04-01

    Unidirectional base station antenna design using Magneto-Electric Dipole (MED) has created enormous interest among the researchers due to its excellent radiation characteristics like low back radiation, symmetrical radiation at E-plane and H-plane compared to conventional patch antenna. Generally, dual polarized antennas are used to increase channel capacity and reliability of the communication systems. In order to serve the evolving mobile communication standards like long term evolution LTE and beyond, unidirectional dual polarized MED antenna are required to have broad impedance bandwidth, broad half power beamwidth, high port isolation, low cross polarization level, high front to back ratio and high gain. In this paper, the critical electrical requirements of the base station antenna and frequently used frequency bands for modern mobile communication have been presented. It is followed by brief review on broadband patch antenna and discussion on complementary antenna concepts. Finally, the performance of linearly polarized and dual polarized magneto-electric dipole antennas along with their feeding techniques are discussed and summarized. Also, design and modeling of developed MED antenna is presented.

  7. Layout and cabling considerations for a large communications antenna array

    NASA Technical Reports Server (NTRS)

    Logan, R. T., Jr.

    1993-01-01

    Layout considerations for a large deep space communications antenna array are discussed. A fractal geometry for the antenna layout is described that provides optimal packing of antenna elements, efficient cable routing, and logical division of the array into identical sub-arrays.

  8. Dual-band microstrip patch antenna based on metamaterial refractive surface

    NASA Astrophysics Data System (ADS)

    Salhi, Ridha; Labidi, Mondher; Boujemaa, Mohamed Ali; Choubani, Fethi

    2017-06-01

    In this paper, we present a new design of microstrip patch antenna based on metamaterial refractive surface (MRS). By optimizing the air gap between the MRS layer and the patch antenna to be 7 mm, the band width and the gain of the proposed antenna are significantly enhanced. The proposed prototype presents a dual band antenna. The center frequency for the first band is 2.44 GHz and the generated bandwidth is 25 MHz. The second band has a center frequency of 2.8 GHz and with a bandwidth of 50 MHz. The simulation results are analyzed and discussed in terms of return loss, gain and radiation pattern using electromagnetic simulator software. Finally, the designed dual band antenna is fabricated and different measurement results are performed and compared with simulation results in order to validate its performances. The proposed antenna supports WiBro (wireless broadband), ISM, WiFi, Bluetooth, WiMAX and radars services.

  9. Reconfigurable Yagi-Uda antenna based on a silicon reflector with a solid-state plasma.

    PubMed

    Kim, Da-Jin; Park, Jang-Soon; Kim, Cheol Ho; Hur, Jae; Kim, Choong-Ki; Cho, Young-Kyun; Ko, Jun-Bong; Park, Bonghyuk; Kim, Dongho; Choi, Yang-Kyu

    2017-12-08

    This paper describes the fabrication and characterization of a reconfigurable Yagi-Uda antenna based on a silicon reflector with a solid-state plasma. The silicon reflector, composed of serially connected p-i-n diodes, forms a highly dense solid-state plasma by injecting electrons and holes into the intrinsic region. When this plasma silicon reflector is turned on, the front-realized gain of the antenna increases by more than 2 dBi beyond 5.3 GHz. To achieve the large gain increment, the structure of the antenna is carefully designed with the aid of semiconductor device simulation and antenna simulation. By using an aluminum nitride (AlN) substrate with high thermal conductivity, self-heating effects from the high forward current in the p-i-n diode are efficiently suppressed. By comparing the antenna simulation data and the measurement data, we estimated the conductivity of the plasma silicon reflector in the on-state to be between 10 4 and 10 5  S/m. With these figures, silicon material with its technology is an attractive tunable material for a reconfigurable antenna, which has attracted substantial interest from many areas, such as internet of things (IoT) applications, wireless network security, cognitive radio, and mobile and satellite communications as well as from multiple-input-multiple-output (MIMO) systems.

  10. Synthesis of a large communications aperture using small antennas

    NASA Technical Reports Server (NTRS)

    Resch, George M.; Cwik, T. W.; Jamnejad, V.; Logan, R. T.; Miller, R. B.; Rogstad, Dave H.

    1994-01-01

    In this report we compare the cost of an array of small antennas to that of a single large antenna assuming both the array and single large antenna have equal performance and availability. The single large antenna is taken to be one of the 70-m antennas of the Deep Space Network. The cost of the array is estimated as a function of the array element diameter for three different values of system noise temperature corresponding to three different packaging schemes for the first amplifier. Array elements are taken to be fully steerable paraboloids and their cost estimates were obtained from commercial vendors. Array loss mechanisms and calibration problems are discussed. For array elements in the range 3 - 35 m there is no minimum in the cost versus diameter curve for the three system temperatures that were studied.

  11. Qualification of UHF Antenna for Extreme Martian Thermal Environments

    NASA Technical Reports Server (NTRS)

    Ramesham, Rajeshuni; Amaro, Luis R.; Brown, Paula R.; Usiskin, Robert

    2013-01-01

    The purpose of this development was to validate the use of the external Rover Ultra High Frequency (RUHF) antenna for space under extreme thermal environments to be encountered during the surface operations of the Mars Science Laboratory (MSL) mission. The antenna must survive all ground operations plus the nominal 670 Martian sol mission that includes summer and winter seasons of the Mars thermal environment.The qualification effort was to verify that the RUHF antenna design and its bonding and packaging processes are adequate to survive the harsh environmental conditions. The RUHF is a quadrifilar helix antenna mounted on the MSL Curiosity rover deck. The main components of the RUHF antenna are the helix structure, feed cables, and hybrid coupler, and the high-power termination load. In the case of MSL rover externally mounted hardware, not only are the expected thermal cycle depths severe, but there are temperature offsets between the Mars summer and winter seasons. The total number of temperature cycles needed to be split into two regimes of summer cycles and winter cycles. The qualification test was designed to demonstrate a survival life of three times more than all expected ground testing, plus a nominal 670 Martian sol missions. Baseline RF tests and a visual inspection were performed prior to the start of the qualification test. Functional RF tests were performed intermittently during chamber breaks over the course of the qualification test. For the RF return loss measurements, the antenna was tested in a controlled environment outside the thermal chamber with a vector network analyzer that was calibrated over the antenna s operational frequency range. A total of 2,010 thermal cycles were performed. Visual inspection showed a dulling of the solder material. This change will not affect the performance of the antenna. No other changes were observed. RF tests were performed on the RUHF helix antenna, hybrid, and load after the 2,010 qualification cycles test

  12. 47 CFR 80.863 - Antenna system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Antenna system. 80.863 Section 80.863... Antenna system. (a) An antenna system must be installed which is as nondirectional and as efficient as is... construction of the required antenna must insure operation in time of emergency. (b) If the required antenna is...

  13. 47 CFR 80.863 - Antenna system.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Antenna system. 80.863 Section 80.863... Antenna system. (a) An antenna system must be installed which is as nondirectional and as efficient as is... construction of the required antenna must insure operation in time of emergency. (b) If the required antenna is...

  14. 47 CFR 80.863 - Antenna system.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Antenna system. 80.863 Section 80.863... Antenna system. (a) An antenna system must be installed which is as nondirectional and as efficient as is... construction of the required antenna must insure operation in time of emergency. (b) If the required antenna is...

  15. 47 CFR 80.863 - Antenna system.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Antenna system. 80.863 Section 80.863... Antenna system. (a) An antenna system must be installed which is as nondirectional and as efficient as is... construction of the required antenna must insure operation in time of emergency. (b) If the required antenna is...

  16. Proceedings of the 2010 Antenna Applications Symposium Held in Monticello, Illinois on 21-23 September 2010. Volume 2

    DTIC Science & Technology

    2010-12-01

    papers relating to antenna arrays and elements, millimeter wave antennas, simulation and measurement of antennas, integrated antennas, and antenna...Hansen 282 v Artificial Impedance Surface Antenna Design and Simulation D.J. Gregoire and J.S. Colburn 288 uCAST - A New Generation UTD...radiating mode to be self-resonant in the electrically small region. 260 hs (cm) Predicted L0 (nH) Simulated L0 (nH) R1 (Ω) Q1 -- -- -- 7.5

  17. Antenna cab interior showing equipment rack and fiberglass antenna panels, ...

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

    Antenna cab interior showing equipment rack and fiberglass antenna panels, looking west. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

  18. Antenna cab interior showing equipment rack and fiberglass antenna panels, ...

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

    Antenna cab interior showing equipment rack and fiberglass antenna panels, looking southeast. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

  19. A new planar broadband antenna based on meandered line loops for portable wireless communication devices

    NASA Astrophysics Data System (ADS)

    Alibakhshi-Kenari, Mohammad; Naser-Moghadasi, Mohammad; Sadeghzadeh, R. A.; Virdee, Bal S.; Limiti, Ernesto

    2016-07-01

    This article presents the design of a novel planar antenna structure comprising two pairs of interconnected meandered line loops that are grounded to a truncated T-shaped ground plane through two via holes. The T-shaped ground plane is used as a reflector to enhance the performance of the antenna. The resulting antenna is compact occupying an area of 38.5 × 36.6 mm2 (0.070λo × 0.067λo), where free-space wavelength is 550 MHz. The antenna radiates omnidirectionally in the E plane across its operational bandwidth (550 MHz to 3.85 GHz) with peak gain and efficiency of 5.5 dBi and 90.1%, respectively, at 2.35 GHz and reflection coefficient better than -10 dB. These characteristics make the antenna suitable for numerous applications, in particular, JCDMA, UHF RFID, GSM 900, GPS, KPCS, DCS, IMT-2000, WiMAX, WiFi, and Bluetooth.

  20. Design and characterisation of a phased antenna array for intact breast hyperthermia.

    PubMed

    Curto, Sergio; Garcia-Miquel, Aleix; Suh, Minyoung; Vidal, Neus; Lopez-Villegas, Jose M; Prakash, Punit

    2018-05-01

    Currently available hyperthermia technology is not well suited to treating cancer malignancies in the intact breast. This study investigates a microwave applicator incorporating multiple patch antennas, with the goal of facilitating controllable power deposition profiles for treating lesions at diverse locations within the intact breast. A 3D-computational model was implemented to assess power deposition profiles with 915 MHz applicators incorporating a hemispheric groundplane and configurations of 2, 4, 8, 12, 16 and 20 antennas. Hemispheric breast models of 90 mm and 150 mm diameter were considered, where cuboid target volumes of 10 mm edge length (1 cm 3 ) and 30 mm edge length (27 cm 3 ) were positioned at the centre of the breast, and also located 15 mm from the chest wall. The average power absorption (αPA) ratio expressed as the ratio of the PA in the target volume and in the full breast was evaluated. A 4-antenna proof-of-concept array was fabricated and experimentally evaluated. Computational models identified an optimal inter-antenna spacing of 22.5° along the applicator circumference. Applicators with 8 and 12 antennas excited with constant phase presented the highest αPA at centrally located and deep-seated targets, respectively. Experimental measurements with a 4-antenna proof-of-concept array illustrated the potential for electrically steering power deposition profiles by adjusting the relative phase of the signal at antenna inputs. Computational models and experimental results suggest that the proposed applicator may have potential for delivering conformal thermal therapy in the intact breast.

  1. Antenna cab interior showing waveguide from external parabolic antenna (later ...

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

    Antenna cab interior showing waveguide from external parabolic antenna (later addition), looking north. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

  2. Antenna Calibration and Measurement Equipment

    NASA Technical Reports Server (NTRS)

    Rochblatt, David J.; Cortes, Manuel Vazquez

    2012-01-01

    A document describes the Antenna Calibration & Measurement Equipment (ACME) system that will provide the Deep Space Network (DSN) with instrumentation enabling a trained RF engineer at each complex to perform antenna calibration measurements and to generate antenna calibration data. This data includes continuous-scan auto-bore-based data acquisition with all-sky data gathering in support of 4th order pointing model generation requirements. Other data includes antenna subreflector focus, system noise temperature and tipping curves, antenna efficiency, reports system linearity, and instrument calibration. The ACME system design is based on the on-the-fly (OTF) mapping technique and architecture. ACME has contributed to the improved RF performance of the DSN by approximately a factor of two. It improved the pointing performances of the DSN antennas and productivity of its personnel and calibration engineers.

  3. Measurements of AAFE RADSCAT antenna characteristics

    NASA Technical Reports Server (NTRS)

    Cross, A. E.; Jones, W. L., Jr.; Jones, A. L.

    1977-01-01

    Antenna characteristics (active and passive) for a modified AAFE-RADSCAT parabolic dish antenna are documented for a variety of antenna configurations. The modified antenna was a replacement for the original unit which was damaged in January 1975. Pattern measurements made at Langley Research Center and Johnson Space Center are presented, with an analysis of the results. Antenna loss measurements are also presented and summarized.

  4. A generalized method for determining radiation patterns of aperture antennas and its application to reflector antennas. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Paknys, J. R.

    1982-01-01

    The reflector antenna may be thought of as an aperture antenna. The classical solution for the radiation pattern of such an antenna is found by the aperture integration (AI) method. Success with this method depends on how accurately the aperture currents are known beforehand. In the past, geometrical optics (GO) has been employed to find the aperture currents. This approximation is suitable for calculating the main beam and possibly the first few sidelobes. A better approximation is to use aperture currents calculated from the geometrical theory of diffraction (GTD). Integration of the GTD currents over and extended aperture yields more accurate results for the radiation pattern. This approach is useful when conventional AI and GTD solutions have no common region of validity. This problem arises in reflector antennas. Two dimensional models of parabolic reflectors are studied; however, the techniques discussed can be applied to any aperture antenna.

  5. Development and coupling analysis of active skin antenna

    NASA Astrophysics Data System (ADS)

    Zhou, Jinzhu; Huang, Jin; He, Qingqang; Tang, Baofu; Song, Liwei

    2017-02-01

    An active skin antenna is a multifunctional composite structure that can provide load-bearing structure and steerable beam pointing functions, and is usually installed in the structural surface of aircraft, warships, and armored vehicles. This paper presents an innovative design of the active skin antenna, which consists of a package layer, control and signal processing layer, and RF (radio frequency) layer. The RF layer is fabricated by low temperature co-fired ceramics, with 64 microstrip antenna elements, tile transmitting and receiving modules, microchannel heat sinks, and feeding networks integrated into a functional block 2.8 mm thick. In this paper, a full-sized prototype of an active skin antenna was designed, fabricated, and tested. Moreover, a coupling analysis method was presented to evaluate the mechanical and electromagnetic performance of the active skin antenna subjected to aerodynamic loads. A deformed experimental system was built to validate the effectiveness of the coupling analysis method, which was also implemented to evaluate the performance of the active skin antenna when subjected to aerodynamic pressure. The fabricated specimen demonstrated structural configuration feasibility, and superior environmental load resistance.

  6. Continuous zoom antenna for mobile visible light communication.

    PubMed

    Zhang, Xuebin; Tang, Yi; Cui, Lu; Bai, Tingzhu

    2015-11-10

    In this paper, we design a continuous zoom antenna for mobile visible light communication (VLC). In the design, a right-angle reflecting prism was adopted to fold the space optical path, thus decreasing the antenna thickness. The surface of each lens in the antenna is spherical, and the system cost is relatively low. Simulation results indicated that the designed system achieved the following performance: zoom ratio of 2.44, field of view (FOV) range of 18°-48°, system gain of 16.8, and system size of 18 mm×6  mm. Finally, we established an indoor VLC system model in a room the size of 5  m ×5  m ×3  m and compared the detection results of the zoom antenna and fixed-focus antenna obtained in a multisource communication environment, a mobile VLC environment, and a multiple-input multiple-output communication environment. The simulation results indicated that the continuous zoom antenna could realize large FOV and high gain. Moreover, the system showed improved stability, mobility, and environmental applicability.

  7. The conical conformal MEMS quasi-end-fire array antenna

    NASA Astrophysics Data System (ADS)

    Cong, Lin; Xu, Lixin; Li, Jianhua; Wang, Ting; Han, Qi

    2017-03-01

    The microelectromechanical system (MEMS) quasi-end-fire array antenna based on a liquid crystal polymer (LCP) substrate is designed and fabricated in this paper. The maximum radiation direction of the antenna tends to the cone axis forming an angle less than 90∘, which satisfies the proximity detection system applied at the forward target detection. Furthermore, the proposed antenna is fed at the ended side in order to save internal space. Moreover, the proposed antenna takes small covering area of the proximity detection system. The proposed antenna is fabricated by using the flexible MEMS process, and the measurement results agree well with the simulation results. This is the first time that a conical conformal array antenna is fabricated by the flexible MEMS process to realize the quasi-end-fire radiation. A pair of conformal MEMS array antennas resonates at 14.2 GHz with its mainlobes tending to the cone axis forming a 30∘ angle and a 31∘ angle separately, and the gains achieved are 1.82 dB in two directions, respectively. The proposed antenna meets the performance requirements for the proximity detection system which has vast application prospects.

  8. Dependence of Helicon Antenna Loading on the Antenna/Plasma Gap and n|| in DIII-D Experiments

    NASA Astrophysics Data System (ADS)

    Pinsker, R. I.; Moeller, C. P.

    2017-10-01

    A comprehensive set of measurements of the plasma loading of a 12-element antenna array, designed to launch helicon waves (i.e., very-high-harmonic fast waves), were performed on DIII-D in 2016. The antenna, operated in the 466 - 486 MHz band, is prototypical of a wider array for a 1-MW-level experiment planned for 2018-9. The dependence of the antenna loading on antenna/plasma gap is of great practical significance, as the gap must be kept greater than a minimum distance to suppress deleterious plasma-material interactions, while the loading must be high enough to retain good efficiency of power transfer to the plasma. While the loading in all examined plasma regimes, including both limited and diverted L-mode discharges and H-mode discharges, decayed exponentially with increasing gap in agreement with simple theory, the characteristic decay length was in all cases larger than expected, motivating the development of a more realistic model. Furthermore, the characteristic decay length did not depend on the launched n||, though the absolute level of loading at a given gap increased as |n||| was decreased from 4 to 2. After the antenna was removed from DIII-D, measurements of the loading produced by a 100 Ω/sq resistive film were carried out on the bench. Both the antenna/film gap and n|| were scanned varied and the results compared with calculations done with the QuickWave FDTD electromagnetics solver. Very good agreement was found in this case. Work supported by the US DOE under DE-FC02-04ER54698.

  9. Quartz antenna with hollow conductor

    DOEpatents

    Leung, Ka-Ngo; Benabou, Elie

    2002-01-01

    A radio frequency (RF) antenna for plasma ion sources is formed of a hollow metal conductor tube disposed within a glass tube. The hollow metal tubular conductor has an internal flow channel so that there will be no coolant leakage if the outer glass tube of the antenna breaks. A portion of the RF antenna is formed into a coil; the antenna is used for inductively coupling RF power to a plasma in an ion source chamber. The antenna is made by first inserting the metal tube inside the glass tube, and then forming the glass/metal composite tube into the desired coil shape.

  10. Integrated, Dual Orthogonal Antennas for Polarimetric Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Pauli, Mario; Wiesbeck, Werner

    2015-04-01

    Ground penetrating radar systems are mostly equipped with single polarized antennas, for example with single linear polarization or with circular polarization. The radiated waves are partly reflected at the ground surface and very often the penetrating waves are distorted in their polarization. The distortion depends on the ground homogeneity and the orientation of the antennas relative to the ground structure. The received signals from the reflecting objects may most times only be classified according to their coverage and intensity. This makes the recognition of the objects difficult or impossible. In airborne and spaceborne Remote Sensing the systems are meanwhile mostly equipped with front ends with dual orthogonal polarized antennas for a full polarimetric operation. The received signals, registered in 2x2 scattering matrices according to co- and cross polarization, are processed for the evaluation of all features of the targets. Ground penetrating radars could also profit from the scientific results of Remote Sensing. The classification of detected objects for their structure and orientation requires more information in the reflected signal than can be measured with a single polarization [1, 2]. In this paper dual linear, orthogonal polarized antennas with a common single, frequency independent phase center, are presented [3]. The relative bandwidth of these antennas can be 1:3, up to 1:4. The antenna is designed to work in the frequency range between 3 GHz and 11 GHz, but can be easily adapted to the GPR frequency range by scaling. The size of the antenna scaled for operation in typical GPR frequencies would approximately be 20 by 20 cm2. By the implementation in a dielectric carrier it could be reduced in size if required. The major problem for ultra wide band, dual polarized antennas is the frequency independent feed network, realizing the required phase shifts. For these antennas a network, which is frequency independent over a wide range, has been

  11. Avoiding Obstructions in Aiming a High-Gain Antenna

    NASA Technical Reports Server (NTRS)

    Edmonds, Karina

    2006-01-01

    The High Gain Antenna Pointing and Obstruction Avoidance software performs computations for pointing a Mars Rover high-gain antenna for communication with Earth while (1) avoiding line-of-sight obstructions (the Martian terrain and other parts of the Rover) that would block communication and (2) taking account of limits in ranges of motion of antenna gimbals and of kinematic singularities in gimbal mechanisms. The software uses simplified geometric models of obstructions and of the trajectory of the Earth in the Martian sky(see figure). It treats all obstructions according to a generalized approach, computing and continually updating the time remaining before interception of each obstruction. In cases in which the gimbal-mechanism design allows two aiming solutions, the algorithm chooses the solution that provides the longest obstruction-free Earth-tracking time. If the communication session continues until an obstruction is encountered in the current pointing solution and the other solution is now unobstructed, then the algorithm automatically switches to the other position. This software also notifies communication- managing software to cease transmission during the switch to the unobstructed position, resuming it when the switch is complete.

  12. Broad band antennas and feed methods

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Benzel, David M.; Twogood, Richard E.

    Two or more Vivaldi antennas, consisting of two plates each, each with the antenna's natural impedance of approximately 100 ohms, are placed in parallel to achieve a 50 ohm impedance in the case of two antennas or other impedances (100/n ohms) for more than two antennas. A single Vivaldi antenna plate (half Vivaldi antenna) over a ground plane can also be used to achieve a 50 ohm impedance, or two or more single plates over a ground plane to achieve other impedances. Unbalanced 50 ohm transmission lines, e.g. coaxial cables, can be used to directly feed, the dual Vivaldi (fourmore » plate) antenna in a center fed angled center departure, or more desirably, a center fed offset departure configuration.« less

  13. Front-Side Microstrip Line Feeding a Raised Antenna Patch

    NASA Technical Reports Server (NTRS)

    Hodges, Richard; Hoppe, Daniel

    2005-01-01

    An improved design concept for a printed-circuit patch antenna and the transmission line that feeds the patch calls for (1) a microstrip transmission line on the front (radiative) side of a printed-circuit board based on a thin, high-permittivity dielectric substrate; (2) using the conductor covering the back side of the circuit board as a common ground plane for both the microstrip line and the antenna patch; (3) supporting the antenna patch in front of the circuit board on a much thicker, lower-permittivity dielectric spacer layer; and (4) connecting the microstrip transmission line to the patch by use of a thin wire or narrow ribbon that extends through the thickness of the spacer and is oriented perpendicularly to the circuit-board plane. The thickness of the substrate is typically chosen so that a microstrip transmission line of practical width has an impedance between 50 and 100 ohms. The advantages of this design concept are best understood in the context of the disadvantages of prior design concepts, as explained

  14. Beam-Steerable Flat-Panel Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Lee, Choon Sae; Lee, Chanam; Miranda, Felix A.

    2005-01-01

    Many space applications require a high-gain antenna that can be easily deployable in space. Currently, the most common high-gain antenna for space-born applications is an umbrella-type reflector antenna that can be folded while being lifted to the Earth orbit. There have been a number of issues to be resolved for this type of antenna. The reflecting surface of a fine wire mesh has to be light in weight and flexible while opening up once in orbit. Also the mesh must be a good conductor at the operating frequency. In this paper, we propose a different type of high-gain antenna for easy space deployment. The proposed antenna is similar to reflector antennas except the curved main reflector is replaced by a flat reconfigurable surface for easy packing and deployment in space. Moreover it is possible to steer the beam without moving the entire antenna system.

  15. S-band antenna phased array communications system

    NASA Technical Reports Server (NTRS)

    Delzer, D. R.; Chapman, J. E.; Griffin, R. A.

    1975-01-01

    The development of an S-band antenna phased array for spacecraft to spacecraft communication is discussed. The system requirements, antenna array subsystem design, and hardware implementation are examined. It is stated that the phased array approach offers the greatest simplicity and lowest cost. The objectives of the development contract are defined as: (1) design of a medium gain active phased array S-band communications antenna, (2) development and test of a model of a seven element planar array of radiating elements mounted in the appropriate cavity matrix, and (3) development and test of a breadboard transmit/receive microelectronics module.

  16. The development of inflatable array antennas

    NASA Technical Reports Server (NTRS)

    Huang, J.

    2001-01-01

    Inflatable array antennas are being developed to significantly reduce the mass, the launch vehicle's stowage volume, and the cost of future spacecraft systems. Three inflatable array antennas, recently developed for spacecraft applications, are a 3.3 m x 1.0 m L-band synthetic-aperture radar (SAR) array, a 1.0 m-diameter X-band telecom reflectarray, and a 3 m-diameter Ka-band telecom reflectarray. All three antennas are similar in construction, and each consists of an inflatable tubular frame that supports and tensions a multi-layer thin-membrane RF radiating surface with printed microstrip patches. The L-band SAR array achieved a bandwidth of 80 MHz, an aperture efficiency of 74%, and a total mass of 15 kg. The X-band reflectarray achieved an aperture efficiency of 37%, good radiation patterns, and a total mass of 1.2 kg (excluding the inflation system). The 3 m Ka-band reflectarray achieved a surface flatness of 0.1 mm RMS, good radiation patterns, and a total mass of 12.8 kg (excluding the inflation system). These antennas demonstrated that inflatable arrays are feasible across the microwave and millimeter-wave spectrums. Further developments of these antennas are deemed necessary, in particular, in the area of qualifying the inflatable structures for space-environment usage.

  17. Helicon antenna radiation patterns in a high-density hydrogen linear plasma device

    NASA Astrophysics Data System (ADS)

    Caneses, J. F.; Blackwell, B. D.; Piotrowicz, P.

    2017-11-01

    Antenna radiation patterns in the vicinity of a helicon antenna are investigated in hydrogen plasmas produced in the MAGPIE linear plasma device. Using a uniform cold-plasma full-wave code, we model the wave physics in MAGPIE and find good agreement with experimental wave measurements. We show for the first time which antenna elements in a helicon device couple most strongly to the plasma and discuss the physical mechanism that determines this effect. Helicon wavefields in the near field of the antenna are best described in terms of the group velocity and ray direction, while far from the antenna, helicon wavefields behave like plane waves and are best described in terms of eigen-modes. In addition, we present recent 2D axis-symmetric full-wave simulations of the 120 kW helicon source in ProtoMPEX [Rapp et al., IEEE Trans. Plasma Sci. 44(12), 3456-3464 (2016); Caughman et al., J. Vac. Sci. Technol. Vac. Surf. Films 35, 03E114 (2017); and Goulding et al., Fusion Sci. Technol. 72(4), 588-594 (2017)] ( n e ˜ 5 × 1019 m-3, B 0 ˜ 70 mT, and f = 13.56 MHz) where the antenna radiation patterns are evident, and we provide an interpretation of the numerical results using the ideas developed in this paper.

  18. Response functions of free mass gravitational wave antennas

    NASA Technical Reports Server (NTRS)

    Estabrook, F. B.

    1985-01-01

    The work of Gursel, Linsay, Spero, Saulson, Whitcomb and Weiss (1984) on the response of a free-mass interferometric antenna is extended. Starting from first principles, the earlier work derived the response of a 2-arm gravitational wave antenna to plane polarized gravitational waves. Equivalent formulas (generalized slightly to allow for arbitrary elliptical polarization) are obtained by a simple differencing of the '3-pulse' Doppler response functions of two 1-arm antennas. A '4-pulse' response function is found, with quite complicated angular dependences for arbitrary incident polarization. The differencing method can as readily be used to write exact response functions ('3n+1 pulse') for antennas having multiple passes or more arms.

  19. Metamaterial-based "sabre" antenna

    NASA Astrophysics Data System (ADS)

    Hafdallah Ouslimani, Habiba; Yuan, Tangjie; Kanane, Houcine; Priou, Alain; Collignon, Gérard; Lacotte, Guillaume

    2014-05-01

    The "sabre" antenna is an array of two monopole elements, vertically polarized with omnidirectional radiation patterns, and placed on either side of a composite material on the tail of an airplane. As an in-phase reflector plane, the antenna uses a compact dual-layer high-impedance surface (DL-HIS) with offset mushroom-like Sivenpiper square shape unit cells. This topology allows one to control both operational frequency and bandgap width, while reducing the total height of the antenna to under λ0/36. The designed antenna structure has a wide bandwidth higher than 24% around 1.4 GHz. The measurements and numerical simulations agree very well.

  20. Antenna analysis using properties of metamaterials

    NASA Astrophysics Data System (ADS)

    Mitra, Atindra K.; Hu, Colin; Maxwell, Kasandra

    2010-04-01

    As part of the Student Internship Programs at Wright-Patterson Air Force Base, including the AFRL Wright Scholar Program for High School Students and the AFRL STEP Program, sample results from preliminary investigation and analysis of integrated antenna structures are reported. Investigation of these novel integrated antenna geometries can be interpreted as a continuation of systems analysis under the general topic area of potential integrated apertures for future software radar/radio solutions [1] [2]. Specifically, the categories of novel integrated aperture geometries investigated in this paper include slotted-fractal structures on microstrip rectangular patch antenna models in tandem with the analysis of exotic substrate materials comprised of a type of synthesized electromagnetic structure known as metamaterials [8] - [10].

  1. Multi-functional Chassis-based Antennas Using Characteristic Mode Theory

    NASA Astrophysics Data System (ADS)

    Kishor, Krishna Kumar

    Designing antennas for handheld devices is quite challenging primarily due to the limited real-estate available, and the fact that internal antennas occupy a large volume. With the need to support a variety of radio systems such as GSM, LTE and WiFi that operate in a wide range of frequency bands, multi-band, wideband and frequency reconfigurable antenna designs have been explored in the literature. Moreover, to support higher data rates, the Long Term Evolution Advanced (LTE-A) standard has been introduced, which requires supporting multiple input multiple output (MIMO) antenna technology and carrier aggregation (CA) on a handheld device. Both of these benefit from the use of multiple antennas or multi-port antennas, but with the limited space available, adding more internal antennas may not be easily possible. Additionally, to realize the benefits of these technologies the multiple antenna ports have to be well isolated from each other. This thesis explores the utilization of the ground plane (or chassis) of a handheld device as an antenna to meet some of these challenges. To achieve this, the theory of characteristic modes (TCM) for conducting bodies is relied upon, to determine the eigen-currents supported on the chassis. The orthogonality properties of these eigencurrents, and their corresponding far-field eigenfields (electric and magnetic) makes TCM a good tool to design multiple antennas with high isolation. This is demonstrated in this thesis via the design of four chassis-based antennas that have different functionalities. The first design is a two port MIMO antenna utilizing a combination of eigenmodes to achieve port isolation. The second design is a pattern reconfigurable MIMO antenna that can operate in two states at 2.28 GHz. The third design is a four port antenna that operates in three frequency bands, with two bands below 1 GHz for CA and the remaining two ports for MIMO communication. The final design is a five port antenna that supports MIMO

  2. Surface wave and linear operating mode of a plasma antenna

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bogachev, N. N., E-mail: bgniknik@yandex.ru; Bogdankevich, I. L.; Gusein-zade, N. G.

    The relation between the propagation conditions of a surface electromagnetic wave along a finiteradius plasma cylinder and the linear operating mode of a plasma antenna is investigated. The solution to the dispersion relation for a surface wave propagating along a finite-radius plasma cylinder is analyzed for weakly and strongly collisional plasmas. Computer simulations of an asymmetrical plasma dipole antenna are performed using the KARAT code, wherein the dielectric properties of plasma are described in terms of the Drude model. The plasma parameters corresponding to the linear operating mode of a plasma antenna are determined. It is demonstrated that the characteristicsmore » of the plasma antenna in this mode are close to those of an analogous metal antenna.« less

  3. An antenna pointing mechanism for large reflector antennas

    NASA Technical Reports Server (NTRS)

    Heimerdinger, H.

    1981-01-01

    An antenna pointing mechanism for large reflector antennas on direct broadcasting communication satellites was built and tested. After listing the requirements and constraints for this equipment the model is described, and performance figures are given. Futhermore, results of the qualification level tests, including functional, vibrational, thermovacuum, and accelerated life tests are reported. These tests were completed successfully.

  4. Antenna structure with distributed strip

    DOEpatents

    Rodenbeck, Christopher T.

    2008-10-21

    An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

  5. Antenna structure with distributed strip

    DOEpatents

    Rodenbeck, Christopher T [Albuquerque, NM

    2008-03-18

    An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

  6. Evaluation of a quarterwave stub antenna for TIROS satellite application

    NASA Astrophysics Data System (ADS)

    Stogner, L. B.

    1980-06-01

    The TIROS-N quarterwave stub antenna communicated accurate position locations during low power level operations based on data processed by the Local User's Terminal (LUT) and Service ARGOS. This style of antenna is the marine mammal transmitter package. The antenna gain and radiation pattern and vertical polarization enhance the applicability. However, for marine mammal transmitter applications, a spring at the base of the antenna is required to provide flexibility and protection to the animal and the antenna must serve as a seawater sensor requiring it to be insulated from the seawater environment except at the sensory location. These problems appear solved for the NIMBUS system, and the TIROS system will be designed accordingly.

  7. Advanced Antenna Measurement Processing

    DTIC Science & Technology

    2014-06-18

    reflector antenna where the reflector functions as a passive scatterer. Here we proposed to demonstrate this separation scheme using experimentally derived...orders in the multiple reflections between these antennas . The nature of these composite patterns is not known a priori so one cannot know the accuracy...SECURITY CLASSIFICATION OF: This research project is focused on the advancement of methods of post measurement processing of antenna pattern

  8. A Passive Temperature-Sensing Antenna Based on a Bimetal Strip Coil.

    PubMed

    Shi, Xianwei; Yang, Fan; Xu, Shenheng; Li, Maokun

    2017-03-23

    A passive temperature-sensing antenna is presented in this paper, which consists of a meandering dipole, a bimetal strip and a back cavity. The meandering dipole is divided into two parts: the lower feeding part and the upper radiating part, which maintain electric contact during operation. As a sensing component, a bimetal strip coil offers a twisting force to rotate the lower feeding part of the antenna when the temperature varies. As a result, the effective length of the dipole antenna changes, leading to a shift of the resonant frequency. Furthermore, a metal back cavity is added to increase the antenna's quality factor Q, which results in a high-sensitivity design. An antenna prototype is designed, fabricated, and measured, which achieves a sensitivity larger than 4.00 MHz/°C in a temperature range from 30 °C to 50 °C and a read range longer than 4 m. Good agreement between the simulation and measurement results is obtained.

  9. Satellite Antenna Systems

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Through the Technology Affiliates Program at the Jet Propulsion Laboratory, the ACTS antenna system was transferred from experimental testing status to commercial development with KVH Industries, Inc. The ACTS design enables mobile satellite antennas to remain pointed at the satellite, regardless of the motion or vibration on which it is mounted. KVH's first product based on the ACTS design is a land-mobile satellite antenna system that will enable direct broadcast satellite television aboard moving trucks, recreational vehicles, trains, and buses. Future products could include use in broadcasting, emergency medical and military vehicles.

  10. Volumetric pattern analysis of fuselage-mounted airborne antennas. Ph.D. Thesis; [prediction analysis techniques for antenna radiation patterns of microwave antennas on commercial aircraft

    NASA Technical Reports Server (NTRS)

    Yu, C. L.

    1976-01-01

    A volumetric pattern analysis of fuselage-mounted airborne antennas at high frequencies was investigated. The primary goal of the investigation was to develop a numerical solution for predicting radiation patterns of airborne antennas in an accurate and efficient manner. An analytical study of airborne antenna pattern problems is presented in which the antenna is mounted on the fuselage near the top or bottom. Since this is a study of general-type commercial aircraft, the aircraft was modeled in its most basic form. The fuselage was assumed to be an infinitely long perfectly conducting elliptic cylinder in its cross-section and a composite elliptic cylinder in its elevation profile. The wing, cockpit, stabilizers (horizontal and vertical) and landing gear are modeled by "N" sided bent or flat plates which can be arbitrarily attached to the fuselage. The volumetric solution developed utilizes two elliptic cylinders, namely, the roll plane and elevation plane models to approximate the principal surface profile (longitudinal and transverse) at the antenna location. With the belt concept and the aid of appropriate coordinate system transformations the solution can be used to predict the volumetric patterns of airborne antennas in an accurate and efficient manner. Applications of this solution to various airborne antenna problems show good agreement with scale model measurements. Extensive data are presented for a microwave landing antenna system.

  11. Tunable Reduced Size Planar Folded Slot Antenna Utilizing Varactor Diodes

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Ponchak, George E.; Jordan, Jennifer L.; Jastram, Nathan; Mahaffey, Joshua V.

    2010-01-01

    A tunable folded slot antenna that utilizes varactor diodes is presented. The antenna is fabricated on Rogers 6006 Duriod with a dielectric constant and thickness of 6.15 and 635 m, respectively. A copper cladding layer of 17 m defines the antenna on the top side (no ground on backside). The antenna is fed with a CPW 50 (Omega) feed line, has a center frequency of 3 GHz, and incorporates Micrometrics microwave hyper-abrupt 500MHV varactors to tune the resonant frequency. The varactors have a capacitance range of 2.52 pF at 0 V to 0.4 pF at 20 V; they are placed across the radiating slot of the antenna. The tunable 10 dB bandwidth of the 3 GHz antenna is 150 MHz. The varactors also reduce the size of the antenna by 30% by capacitively loading the resonating slot line. At the center frequency, 3 GHz, the antenna has a measured return loss of 44 dB and a gain of 1.6 dBi. Full-wave electromagnetic simulations using HFSS are presented that validate the measured data. Index Terms capacitive loading, Duriod, folded slot antenna, varactor.

  12. Compact Planar Ultrawideband Antennas with 3.5/5.2/5.8 GHz Triple Band-Notched Characteristics for Internet of Things Applications.

    PubMed

    Dong, Jian; Li, Qianqian; Deng, Lianwen

    2017-02-10

    Ultrawideband (UWB) antennas, as core devices in high-speed wireless communication, are widely applied to mobile handsets, wireless sensor networks, and Internet of Things (IoT). A compact printed monopole antenna for UWB applications with triple band-notched characteristics is proposed in this paper. The antenna has a very compact size of 10 x 16 mm2 and is composed of a square slotted radiation patch and a narrow rectangular ground plane on the back of the substrate. First, by etching a pair of inverted T-shaped slots at the bottom of the radiation patch, one notched band at 5-6 GHz for rejecting the Wireless Local Area Network (WLAN) is generated. Then, by cutting a comb-shaped slot on the top of the radiation patch, a second notched band for rejecting 3.5 GHz Worldwide Interoperability for Microwave Access (WiMAX) is obtained. Further, by cutting a pair of rectangular slots and a C-shaped slot as well as adding a pair of small square parasitic patches at the center of the radiating patch, two separate notched bands for rejecting 5.2 GHz lower WLAN and 5.8 GHz upper WLAN are realized, respectively. Additionally, by integrating the slotted radiation patch with the narrow rectangular ground plane, an enhanced impedance bandwidth can be achieved, especially at the higher band. The antenna consists of linear symmetrical sections only and is easy for fabrication and fine-tuning. The measured results show that the designed antenna provides a wide impedance bandwidth of 150% from 2.12 to 14.80 GHz for VSWR < 2, except for three notched bands of 3.36-4.16, 4.92-5.36, and 5.68-6.0 GHz. Additionally, the antenna exhibits nearly omnidirectional radiation characteristics, low gain at the stopbands, and flat group delay over the whole UWB except at the stopbands. Simulated and experimental results show that the proposed antenna can provide good frequency-domain and time-domain performances at desired UWB frequencies and be an attractive candidate for portable Io

  13. Ionospheric effects to antenna impedance

    NASA Technical Reports Server (NTRS)

    Bethke, K. H.

    1986-01-01

    The reciprocity between high power satellite antennas and the surrounding plasma are examined. The relevant plasma states for antenna impedance calculations are presented and plasma models, and hydrodynamic and kinetic theory, are discussed. A theory from which a variation in antenna impedance with regard to the radiated power can be calculated for a frequency range well above the plasma resonance frequency is give. The theory can include photo and secondary emission effects in antenna impedance calculations.

  14. Smart Antenna UKM Testbed for Digital Beamforming System

    NASA Astrophysics Data System (ADS)

    Islam, Mohammad Tariqul; Misran, Norbahiah; Yatim, Baharudin

    2009-12-01

    A new design of smart antenna testbed developed at UKM for digital beamforming purpose is proposed. The smart antenna UKM testbed developed based on modular design employing two novel designs of L-probe fed inverted hybrid E-H (LIEH) array antenna and software reconfigurable digital beamforming system (DBS). The antenna is developed based on using the novel LIEH microstrip patch element design arranged into [InlineEquation not available: see fulltext.] uniform linear array antenna. An interface board is designed to interface to the ADC board with the RF front-end receiver. The modular concept of the system provides the capability to test the antenna hardware, beamforming unit, and beamforming algorithm in an independent manner, thus allowing the smart antenna system to be developed and tested in parallel, hence reduces the design time. The DBS was developed using a high-performance [InlineEquation not available: see fulltext.] floating-point DSP board and a 4-channel RF front-end receiver developed in-house. An interface board is designed to interface to the ADC board with the RF front-end receiver. A four-element receiving array testbed at 1.88-2.22 GHz frequency is constructed, and digital beamforming on this testbed is successfully demonstrated.

  15. Control System and Tests for the 13.2-m RAEGE Antenna at Yebes

    NASA Astrophysics Data System (ADS)

    de Vicente, P.; Bolaño, R.; Barbas, L.

    2014-12-01

    The RAEGE network is being deployed. The antenna at the Yebes Observatory is the first one in the network, and its construction finished in October 2013. During the construction phase, the remote control system for the antenna and the receivers was developed, and during the commisioning time the software was tested by MT-Mechatronics. As a result, both the control system from MT-Mechatronics and the remote control system by the IGN-CDT were debugged. We have tested the basic functionality of the antenna operated as a single dish telescope. First light at S, X, and Ka band was achieved on February 10^{th}. Afterwards a pointing model for the whole sky was determined, together with an optimum focus position as a function of elevation. Commisioning is not finished yet, and the antenna will be totally delivered to the IGN-CDT in the next weeks. VLBI equipment will be installed within three months, and VLBI observations are foreseen by the end of 2014. In this paper, we provide an overview of the control system and of the main results achieved.

  16. A new approach for shaping of dual-reflector antennas

    NASA Technical Reports Server (NTRS)

    Lee, Teh-Hong; Burnside, W. D.; Rudduck, Roger C.

    1987-01-01

    The shaping of 2-D dual-reflector antenna systems to generate a prescribed distribution with uniform phase at the aperture of the second reflector is examined. This method is based on the geometrical nature of Cassegrain and Gregorian dual-reflector antennas. The method of syntheses satisfies the principles of geometrical optics which are the foundations of dual-reflector designs. Instead of setting up differential equations or heuristically designing the subreflector, a set of algebraic equations is formulated and solved numerically to obtain the desired surfaces. The caustics of the reflected rays from the subreflector can be obtained and examined. Several examples of 2-D dual-reflector shaping are shown to validate the study. Geometrical optics and physical optics are used to calculate the scattered fields from the reflectors.

  17. Microwave Imaging Sensor Using Compact Metamaterial UWB Antenna with a High Correlation Factor.

    PubMed

    Islam, Md Moinul; Islam, Mohammad Tariqul; Faruque, Mohammad Rashed Iqbal; Samsuzzaman, Md; Misran, Norbahiah; Arshad, Haslina

    2015-07-23

    The design of a compact metamaterial ultra-wideband (UWB) antenna with a goal towards application in microwave imaging systems for detecting unwanted cells in human tissue, such as in cases of breast cancer, heart failure and brain stroke detection is proposed. This proposed UWB antenna is made of four metamaterial unit cells, where each cell is an integration of a modified split ring resonator (SRR), capacitive loaded strip (CLS) and wire, to attain a design layout that simultaneously exhibits both a negative magnetic permeability and a negative electrical permittivity. This design results in an astonishing negative refractive index that enables amplification of the radiated power of this reported antenna, and therefore, high antenna performance. A low-cost FR4 substrate material is used to design and print this reported antenna, and has the following characteristics: thickness of 1.6 mm, relative permeability of one, relative permittivity of 4.60 and loss tangent of 0.02. The overall antenna size is 19.36 mm × 27.72 mm × 1.6 mm where the electrical dimension is 0.20 λ × 0.28 λ × 0.016 λ at the 3.05 GHz lower frequency band. Voltage Standing Wave Ratio (VSWR) measurements have illustrated that this antenna exhibits an impedance bandwidth from 3.05 GHz to more than 15 GHz for VSWR < 2 with an average gain of 4.38 dBi throughout the operating frequency band. The simulations (both HFSS and computer simulation technology (CST)) and the measurements are in high agreement. A high correlation factor and the capability of detecting tumour simulants confirm that this reported UWB antenna can be used as an imaging sensor.

  18. Microwave Imaging Sensor Using Compact Metamaterial UWB Antenna with a High Correlation Factor

    PubMed Central

    Islam, Md. Moinul; Islam, Mohammad Tariqul; Faruque, Mohammad Rashed Iqbal; Samsuzzaman, Md.; Misran, Norbahiah; Arshad, Haslina

    2015-01-01

    The design of a compact metamaterial ultra-wideband (UWB) antenna with a goal towards application in microwave imaging systems for detecting unwanted cells in human tissue, such as in cases of breast cancer, heart failure and brain stroke detection is proposed. This proposed UWB antenna is made of four metamaterial unit cells, where each cell is an integration of a modified split ring resonator (SRR), capacitive loaded strip (CLS) and wire, to attain a design layout that simultaneously exhibits both a negative magnetic permeability and a negative electrical permittivity. This design results in an astonishing negative refractive index that enables amplification of the radiated power of this reported antenna, and therefore, high antenna performance. A low-cost FR4 substrate material is used to design and print this reported antenna, and has the following characteristics: thickness of 1.6 mm, relative permeability of one, relative permittivity of 4.60 and loss tangent of 0.02. The overall antenna size is 19.36 mm × 27.72 mm × 1.6 mm where the electrical dimension is 0.20 λ × 0.28 λ × 0.016 λ at the 3.05 GHz lower frequency band. Voltage Standing Wave Ratio (VSWR) measurements have illustrated that this antenna exhibits an impedance bandwidth from 3.05 GHz to more than 15 GHz for VSWR < 2 with an average gain of 4.38 dBi throughout the operating frequency band. The simulations (both HFSS and computer simulation technology (CST)) and the measurements are in high agreement. A high correlation factor and the capability of detecting tumour simulants confirm that this reported UWB antenna can be used as an imaging sensor. PMID:28793461

  19. Notch Antennas

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.

    2004-01-01

    Notch antennas, also known as the tapered slot antenna (TSA), have been the topics of research for decades. TSA has demonstrated multi-octave bandwidth, moderate gain (7 to 10 dB), and symmetric E- and H- plane beam patterns and can be used for many different applications. This chapter summarizes the research activities on notch antennas over the past decade with emphasis on their most recent advances and applications. This chapter begins with some discussions on the designs of single TSA; then follows with detailed discussions of issues associated with TSA designs and performance characteristics. To conclude the chapter, some recent developments in TSA arrays and their applications are highlighted.

  20. A comparative study of radiofrequency antennas for Helicon plasma sources

    NASA Astrophysics Data System (ADS)

    Melazzi, D.; Lancellotti, V.

    2015-04-01

    Since Helicon plasma sources can efficiently couple power and generate high-density plasma, they have received interest also as spacecraft propulsive devices, among other applications. In order to maximize the power deposited into the plasma, it is necessary to assess the performance of the radiofrequency (RF) antenna that drives the discharge, as typical plasma parameters (e.g. the density) are varied. For this reason, we have conducted a comparative analysis of three Helicon sources which feature different RF antennas, namely, the single-loop, the Nagoya type-III and the fractional helix. These antennas are compared in terms of input impedance and induced current density; in particular, the real part of the impedance constitutes a measure of the antenna ability to couple power into the plasma. The results presented in this work have been obtained through a full-wave approach which (being hinged on the numerical solution of a system of integral equations) allows computing the antenna current and impedance self-consistently. Our findings indicate that certain combinations of plasma parameters can indeed maximize the real part of the input impedance and, thus, the deposited power, and that one of the three antennas analyzed performs best for a given plasma. Furthermore, unlike other strategies which rely on approximate antenna models, our approach enables us to reveal that the antenna current density is not spatially uniform, and that a correlation exists between the plasma parameters and the spatial distribution of the current density.

  1. Microsecond switchable thermal antenna

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ben-Abdallah, Philippe, E-mail: pba@institutoptique.fr; Benisty, Henri; Besbes, Mondher

    2014-07-21

    We propose a thermal antenna that can be actively switched on and off at the microsecond scale by means of a phase transition of a metal-insulator material, the vanadium dioxide (VO{sub 2}). This thermal source is made of a periodically patterned tunable VO{sub 2} nanolayer, which support a surface phonon-polariton in the infrared range in their crystalline phase. Using electrodes properly registered with respect to the pattern, the VO{sub 2} phase transition can be locally triggered by ohmic heating so that the surface phonon-polariton can be diffracted by the induced grating, producing a highly directional thermal emission. Conversely, when heatingmore » less, the VO{sub 2} layers cool down below the transition temperature, the surface phonon-polariton cannot be diffracted anymore so that thermal emission is inhibited. This switchable antenna could find broad applications in the domain of active thermal coatings or in those of infrared spectroscopy and sensing.« less

  2. Technique for Radiometer and Antenna Array Calibration with Two Antenna Noise Diodes

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2011-01-01

    This paper presents a new technique to calibrate a microwave radiometer and phased array antenna system. This calibration technique uses a radiated noise source in addition to an injected noise sources for calibration. The plane of reference for this calibration technique is the face of the antenna and therefore can effectively calibration the gain fluctuations in the active phased array antennas. This paper gives the mathematical formulation for the technique and discusses the improvements brought by the method over the existing calibration techniques.

  3. JPL Large Advanced Antenna Station Array Study

    NASA Technical Reports Server (NTRS)

    1978-01-01

    In accordance with study requirements, two antennas are described: a 30 meter standard antenna and a 34 meter modified antenna, along with a candidate array configuration for each. Modified antenna trade analyses are summarized, risks analyzed, costs presented, and a final antenna array configuration recommendation made.

  4. Far-Field RF Sheaths due to Shear Alfvén Waves in the LAPD

    NASA Astrophysics Data System (ADS)

    Martin, Michael; van Compernolle, Bart; Gekelman, Walter; Pribyl, Pat; Carter, Troy; D'Ippolito, Daniel A.; Myra, James R.

    2013-10-01

    Ion cyclotron resonance heating (ICRH) is an important tool in current fusion experiments and will be an essential heating component in ITER. ICRH could be limited by deleterious effects due to the formation of radio frequency (RF) sheaths in the near-field (at the antenna) and in the far-field (e.g. in the divertor region). Far-field sheaths are thought to be caused by the direct launch of or mode conversion to a shear Alfvén wave with an electric field component parallel to the background magnetic field at the wall. In this experiment a limiter plate was inserted into a cylindrical plasma in the LAPD (ne ~ 1010-11 cm-3, Te ~ 5 eV, B0 = 1.2 kG) and RF sheaths were created by directly launching the shear Alfven wave. Plasma potential measurements were made with an emissive probe. DC plasma potential rectification was observed along field lines connected to the plate, serving as an indirect measure of RF sheath formation. 2-D maps of plasma properties and rectified plasma potential will be presented. This research is part of an ongoing campaign to study the formation and structure of RF sheaths.

  5. Negative ion source with external RF antenna

    DOEpatents

    Leung, Ka-Ngo; Hahto, Sami K.; Hahto, Sari T.

    2007-02-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source. A converter can be included in the ion source to produce negative ions.

  6. Qualification of a High Accuracy Dual-Axis Antenna Deployment and Trimming Mechanism

    NASA Technical Reports Server (NTRS)

    Gossant, Alain; Morichon, Francois

    2010-01-01

    The Antenna Deployment and Trimming Mechanism Mark 2 (ADTM Mk2) has been developed to answer today's need for a generic antenna deployment and high accuracy pointing mechanism, allowing RF sensing applications and easier dual deployments configurations. This paper presents the design and evolution from its predecessor, the experience of the design team from kick off to qualification and batch manufacture, as well as some lessons learned from ramping up "mass-production" capabilities while implementing customer driven changes. Astrium has manufactured and flown ADTM units for the past 20 years, from an initial deployment-only mechanism developed for the Orion program to today's Eurostar E3000 ADTM family. The Antenna ADTM Mk2 is an evolution of the original ADTM Mk1. Although it uses Mk1 building blocks to minimize risks associated with the development of a new product, it incorporates major evolutions and is the new baseline for Astrium latest generation of Eurostar E3000 telecom satellites.

  7. High-gain Antenna & Terrain

    NASA Image and Video Library

    1997-07-06

    Areas of rocky Martian terrain are seen in this image, taken by the Imager for Mars Pathfinder (IMP) on Sol 2. Portions of a lander petal and deflated airbag are at lower left. The dark disk at center is the high-gain antenna, and the silver cylindrical objects at upper right are part of the antenna's mechanism. An area of relatively smooth terrain is seen at upper right, which may offer clues to how this area was formed, and may be a future target for Sojourner's studies. The black area at lower right and small strip at top center is missing data. http://photojournal.jpl.nasa.gov/catalog/PIA00625

  8. Study of the characteristics of reconfigurable plasma antenna array

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alias, Nur Salihah; Dagang, Ahmad Nazri; Ali, Mohd Tarmizi

    This paper presents a design and simulation of a reconfigurable array of plasma antenna. The plasma column is used as radiating elements instead of metal to create an antenna. The advantages of the plasma antenna over the conventional antenna are its possible to change the operating parameters, such as the working pressure, input power, radius of the discharge tube, resonant frequency, and length of the plasma column. In addition, plasma antenna can be reconfigurable with respect to shape, frequency and radiation parameters in a very short time. The plasma discharge tube was designed with a length of 200 mm, the radiusmore » of the plasma column was 2.5 mm and the coupling sleeve was connected to the SMA as the ground. This simulation was performed by using the simulation software Computer Simulation Technology (CST). The frequency is set in the range of 1 GHz to 10 GHz. The performance of the designed antenna was analyzed in term of return loss, gain and radiation pattern. For reconfigurable plasma antenna array, it shows that the gain is increase when the number of antenna element is increase. The combination of the discharge tube and metal rod as an antenna array has been done, and the result shows that an array with the plasma element can achieve higher gain.« less

  9. 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

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

    PubMed

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

    2012-11-15

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

  11. Optimization of a Circularly Polarized Patch Antenna for Two Frequency Bands

    DTIC Science & Technology

    2015-09-01

    the various techniques that can be used to improve the performance of a circularly polarized microstrip patch antenna . These adjustments include... microstrip antenna . 15. SUBJECT TERMS Patch Antenna , Circular Polarization 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT...Frequency Structural Simulator (HFSS) has allowed engineers to create scalable multiband microstrip antennas . Several factors were taken into

  12. Microelectromechanical Systems Actuator Based Reconfigurable Printed Antenna

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N. (Inventor)

    2005-01-01

    A polarization reconfigurable patch antenna is disclosed. The antenna includes a feed element, a patch antenna element electrically connected to the feed element, and at least one microelectromechanical systems (MEMS) actuator, with a partial connection to the patch antenna element along an edge of the patch antenna element. The polarization of the antenna can be switched between circular polarization and linear polarization through action of the at least one MEMS actuator.

  13. 14 CFR 77.75 - Establishment of antenna farm areas.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Establishment of antenna farm areas. 77.75... (CONTINUED) AIRSPACE OBJECTS AFFECTING NAVIGABLE AIRSPACE Establishment of Antenna Farm Areas § 77.75 Establishment of antenna farm areas. The airspace areas described in the following sections of this subpart are...

  14. 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

  15. A comparison of reflector antenna designs for wide-angle scanning

    NASA Technical Reports Server (NTRS)

    Zimmerman, M.; Lee, S. W.; Houshmand, B.; Rahmatsamii, Y.; Acosta, R. J.

    1989-01-01

    Conventional reflector antennas are typically designed for up to + or - 20 beamwidths scan. An attempt was made to stretch this scan range to some + or - 300 beamwidths. Six single and dual reflector antennas were compared. It is found that a symmetrical parabolic reflector with f/D = 2 and a single circular waveguide feed has the minimum scan loss (only 0.6 dB at Theta sub 0 = 8 deg, or a 114 beamwidths scan). The scan is achieved by tilting the parabolic reflector by an angle equal to the half-scan angle. The f/D may be shortened if a cluster 7 to 19 elements instead of one element is used for the feed. The cluster excitation is adjusted for each new beam scan direction to compensate for the imperfect field distribution over the reflector aperture. The antenna can be folded into a Cassegrain configuration except that, due to spillover and blockage considerations, the amount of folding achievable is small.

  16. To increase controllability of a large flexible antenna by modal optimization

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Wang, Pengpeng; Jiang, Wenjian

    2017-12-01

    Large deployable antennas are widely used in aerospace engineering to meet the envelop limit of rocket fairing. The high flexibility and low damping of antenna has proposed critical requirement not only for stability control of the antenna itself, but also for attitude control of the satellite. This paper aims to increase controllability of a large flexible antenna by modal optimization. Firstly, Sensitivity analysis of antenna modal frequencies to stiffness of support structure and stiffness of scanning mechanism are conducted respectively. Secondly, Modal simulation results of antenna frequencies are given, influences of scanning angles on moment of inertia and modal frequencies are evaluated, and modal test is carried out to validate the simulation results. All the simulation and test results show that, after modal optimization the modal characteristic of the large deployable antenna meets the controllability requirement well.

  17. Boosting the SNR by adding a receive-only endorectal monopole to an external antenna array for high-resolution, T2 -weighted imaging of early-stage cervical cancer with 7-T MRI.

    PubMed

    van Kalleveen, I M L; Hoogendam, J P; Raaijmakers, A J E; Visser, F; Arteaga de Castro, C S; Verheijen, R H M; Luijten, P R; Zweemer, R P; Veldhuis, W B; Klomp, D W J

    2017-09-01

    The aim of this study was to investigate the signal-to-noise ratio (SNR) gain in early-stage cervical cancer at ultrahigh-field MRI (e.g. 7 T) using a combination of multiple external antennas and a single endorectal antenna. In particular, we used an endorectal monopole antenna to increase the SNR in cervical magnetic resonance imaging (MRI). This should allow high-resolution, T 2 -weighted imaging and magnetic resonance spectroscopy (MRS) for metabolic staging, which could facilitate the local tumor status assessment. In a prospective feasibility study, five healthy female volunteers and six patients with histologically proven stage IB1-IIB cervical cancer were scanned at 7 T. We used seven external fractionated dipole antennas for transmit-receive (transceive) and an endorectally placed monopole antenna for reception only. A region of interest, containing both normal cervix and tumor tissue, was selected for the SNR measurement. Separated signal and noise measurements were obtained in the region of the cervix for each element and in the near field of the monopole antenna (radius < 30 mm) to calculate the SNR gain of the endorectal antenna in each patient. We obtained high-resolution, T 2 -weighted images with a voxel size of 0.7 × 0.8 × 3.0 mm 3 . In four cases with optimal placement of the endorectal antenna (verified on the T 2 -weighted images), a mean gain of 2.2 in SNR was obtained at the overall cervix and tumor tissue area. Within a radius of 30 mm from the monopole antenna, a mean SNR gain of 3.7 was achieved in the four optimal cases. Overlap between the two different regions of the SNR calculations was around 24%. We have demonstrated that the use of an endorectal monopole antenna substantially increases the SNR of 7-T MRI at the cervical anatomy. Combined with the intrinsically high SNR of ultrahigh-field MRI, this gain may be employed to obtain metabolic information using MRS and to enhance spatial resolutions to assess tumor invasion

  18. A compact 5.5 GHz band-rejected UWB antenna using complementary split ring resonators.

    PubMed

    Islam, M M; Faruque, M R I; Islam, M T

    2014-01-01

    A band-removal property employing microwave frequencies using complementary split ring resonators (CSRRs) is applied to design a compact UWB antenna wishing for the rejection of some frequency band, which is meanwhile exercised by the existing wireless applications. The reported antenna comprises optimization of a circular radiating patch, in which slotted complementary SRRs are implanted. It is printed on low dielectric FR4 substrate material fed by a partial ground plane and a microstrip line. Validated results exhibit that the reported antenna shows a wide bandwidth covering from 3.45 to more than 12 GHz, with a compact dimension of 22 × 26 mm(2), and VSWR < 2, observing band elimination of 5.5 GHz WLAN band.

  19. Design considerations for the beamwaveguide retrofit of a ground antenna station

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    A primary requirement of the NASA Deep Space Network (DSN) is to provide for optimal reception of very low signal levels. This requirement necessitates optimizing the antenna gain to the total system operating noise level quotient. Low overall system noise levels of 16 to 20 K are achieved by using cryogenically cooled preamplifiers closely coupled with an appropriately balanced antenna gain/spillover design. Additionally, high-power transmitters (up to 400 kW CW) are required for spacecraft emergency command and planetary radar experiments. The frequency bands allocated for deep space telemetry are narrow bands near 2.1 and 2.3 GHz (Ka-band), 7.1 and 8.4 GHz (X-band), and 32 and 34.5 GHz (Ka-band). In addition, planned operations for the Search for Extraterrestrial Intelligence (SETI) program require continuous low-noise receive coverage over the 1 to 10 GHz band. To summarize, DSN antennas must operate efficiently with low receive noise and high-power uplink over the 1 to 35 GHz band.

  20. Dielectric Covered Planar Antennas

    NASA Technical Reports Server (NTRS)

    Llombart Juan, Nuria (Inventor); Lee, Choonsup (Inventor); Chattopadhyay, Goutam (Inventor); Gill, John J. (Inventor); Skalare, Anders J. (Inventor); Siegel, Peter H. (Inventor)

    2014-01-01

    An antenna element suitable for integrated arrays at terahertz frequencies is disclosed. The antenna element comprises an extended spherical (e.g. hemispherical) semiconductor lens, e.g. silicon, antenna fed by a leaky wave waveguide feed. The extended spherical lens comprises a substantially spherical lens adjacent a substantially planar lens extension. A couple of TE/TM leaky wave modes are excited in a resonant cavity formed between a ground plane and the substantially planar lens extension by a waveguide block coupled to the ground plane. Due to these modes, the primary feed radiates inside the lens with a directive pattern that illuminates a small sector of the lens. The antenna structure is compatible with known semiconductor fabrication technology and enables production of large format imaging arrays.

  1. Hybrid Deployable Foam Antennas and Reflectors

    NASA Technical Reports Server (NTRS)

    Rivellini, Tommaso; Willis, Paul; Hodges, Richard; Spitz, Suzanne

    2006-01-01

    Hybrid deployable radio antennas and reflectors of a proposed type would feature rigid narrower apertures plus wider adjoining apertures comprising reflective surfaces supported by open-cell polymeric foam structures (see figure). The open-cell foam structure of such an antenna would be compressed for compact stowage during transport. To initiate deployment of the antenna, the foam structure would simply be released from its stowage mechanical restraint. The elasticity of the foam would drive the expansion of the foam structure to its full size and shape. There are several alternatives for fabricating a reflective surface supported by a polymeric foam structure. One approach would be to coat the foam with a metal. Another approach would be to attach a metal film or a metal-coated polymeric membrane to the foam. Yet another approach would be to attach a metal mesh to the foam. The hybrid antenna design and deployment concept as proposed offers significant advantages over other concepts for deployable antennas: 1) In the unlikely event of failure to deploy, the rigid narrow portion of the antenna would still function, providing a minimum level of assured performance. In contrast, most other concepts for deploying a large antenna from compact stowage are of an "all or nothing" nature: the antenna is not useful at all until and unless it is fully deployed. 2) Stowage and deployment would not depend on complex mechanisms or actuators, nor would it involve the use of inflatable structures. Therefore, relative to antennas deployed by use of mechanisms, actuators, or inflation systems, this antenna could be lighter, cheaper, amenable to stowage in a smaller volume, and more reliable. An open-cell polymeric (e.g., polyurethane) foam offers several advantages for use as a compressible/expandable structural material to support a large antenna or reflector aperture. A few of these advantages are the following: 3) The open cellular structure is amenable to compression to a very

  2. UHF coplanar-slot antenna for aircraft-to-satellite data communications

    NASA Technical Reports Server (NTRS)

    Myhre, R. W.

    1979-01-01

    A lightweight low drag coplanar slot antenna was developed for use on commercial jet aircraft that will provide upper hemisphere coverage in the UHF band at frequencies of 402 and 468 MHz is described. The antenna is designed to transmit meteorological data from wide body jet aircraft to ground users via synchronous meteorological data relay satellites. The low profile antenna (23.5 cm wide by 38.1 cm long slot by 1.9 cm high) is a conformal antenna utilizing the coplanar approach with the advantages of broad frequency bandwidth and improved electrical integrity over wide range of temperature. The antenna is circular polarized, has anon axis gain of near +2.5 dB, and a HPBW greater than 90 deg. Areas discussed include antenna design, radiation characteristics, flight testing, and system performance.

  3. Automated Antenna Design with Evolutionary Algorithms

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  4. Low dielectric polyimide aerogels as substrates for lightweight patch antennas.

    PubMed

    Meador, Mary Ann B; Wright, Sarah; Sandberg, Anna; Nguyen, Baochau N; Van Keuls, Frederick W; Mueller, Carl H; Rodríguez-Solís, Rafael; Miranda, Félix A

    2012-11-01

    The dielectric properties and loss tangents of low-density polyimide aerogels have been characterized at various frequencies. Relative dielectric constants as low as 1.16 were measured for polyimide aerogels made from 2,2'-dimethylbenzidine (DMBZ) and biphenyl 3,3',4,4'-tetracarbozylic dianhydride (BPDA) cross-linked with 1,3,5-triaminophenoxybenzene (TAB). This formulation was used as the substrate to fabricate and test prototype microstrip patch antennas and benchmark against state of practice commercial antenna substrates. The polyimide aerogel antennas exhibited broader bandwidth, higher gain, and lower mass than the antennas made using commercial substrates. These are very encouraging results, which support the potential advantages of the polyimide aerogel-based antennas for aerospace applications.

  5. Stretchable and reversibly deformable radio frequency antennas based on silver nanowires.

    PubMed

    Song, Lingnan; Myers, Amanda C; Adams, Jacob J; Zhu, Yong

    2014-03-26

    We demonstrate a class of microstrip patch antennas that are stretchable, mechanically tunable, and reversibly deformable. The radiating element of the antenna consists of highly conductive and stretchable material with screen-printed silver nanowires embedded in the surface layer of an elastomeric substrate. A 3-GHz microstrip patch antenna and a 6-GHz 2-element patch array are fabricated. Radiating properties of the antennas are characterized under tensile strain and agree well with the simulation results. The antenna is reconfigurable because the resonant frequency is a function of the applied tensile strain. The antenna is thus well suited for applications like wireless strain sensing. The material and fabrication technique reported here could be extended to achieve other types of stretchable antennas with more complex patterns and multilayer structures.

  6. Improving the detectability and imaging capability of ground penetrating radar using novel antenna concepts

    NASA Astrophysics Data System (ADS)

    Koyadan Koroth, Ajith; Bhattacharya, Amitabha

    2017-04-01

    Antennas are key components of Ground Penetrating Radar (GPR) instrumentation. A carefully designed antenna can improve the detectability and imaging capability of a GPR to a great extent without changing the other instrumentations. In this work, we propose four different types of antennas for GPR. They are modifications of a conventional bowtie antenna with great improvement in performance parameters. The designed antennas has also been tested in a stepped frequency type GPR and two dimensional scan images of various targets are presented. Bowtie antennas have been traditionally employed in GPR for its wide impedance bandwidth and radiation properties. The researchers proposed resistive loading to improve the bandwidth of the bowtie antenna and for low ringing pulse radiation. But this method was detrimental for antenna gain and efficiency. Bowtie antennas have a very wide impedance bandwidth. But the useful bandwidth of the antenna has been limited by the radiation pattern bandwidth. The boresight gain of bowtie antennas are found to be unstable beyond a 4:1 bandwidth. In this work, these problems have been addressed and maximum usable bandwidth for the bowtie antennas has been achieved. In this work, four antennas have been designed: namely, 1.) RC loaded bowtie antennas, 2.) RC loaded bowtie with metamaterial lens, 3.) Loop loaded bowtie, 4.) Loop loaded bowtie with directors. The designed antennas were characterized for different parameters like impedance bandwidth, radiation pattern and, gain. In antenna 1, a combined resistive-capacitive loading has been applied by periodic slot cut on the arms of the bowtie and pasting a planar graphite sheet over it. Graphite having a less conductance compared to copper acts as resistive loading. This would minimize the losses compared to lumped resistive loading. The antenna had a 10:1 impedance bandwidth and, a 5:1 pattern bandwidth. In antenna 2, a metamaterial lens has been designed to augment the antenna 1, to improve

  7. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be more...

  8. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be more...

  9. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be more...

  10. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be more...

  11. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be more...

  12. 47 CFR 73.510 - Antenna systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Antenna systems. 73.510 Section 73.510... Noncommercial Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial educational... § 73.316 concerning antenna systems contained in subpart B of this part. (b) Directional antenna. No...

  13. 47 CFR 73.510 - Antenna systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 73.510 Section 73.510... Noncommercial Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial educational... § 73.316 concerning antenna systems contained in subpart B of this part. (b) Directional antenna. No...

  14. 47 CFR 73.510 - Antenna systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Antenna systems. 73.510 Section 73.510... Noncommercial Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial educational... § 73.316 concerning antenna systems contained in subpart B of this part. (b) Directional antenna. No...

  15. 47 CFR 73.510 - Antenna systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Antenna systems. 73.510 Section 73.510... Noncommercial Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial educational... § 73.316 concerning antenna systems contained in subpart B of this part. (b) Directional antenna. No...

  16. 47 CFR 73.510 - Antenna systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Antenna systems. 73.510 Section 73.510... Noncommercial Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial educational... § 73.316 concerning antenna systems contained in subpart B of this part. (b) Directional antenna. No...

  17. Mechanism for Deploying a Long, Thin-Film Antenna from a Rover

    NASA Technical Reports Server (NTRS)

    Lazio, Joseph; Matthews, B.; Nesnas, Issa A.; Zarzhitsky, Dimitri

    2013-01-01

    Observations with radio telescopes address key problems in cosmology, astrobiology, heliophysics, and planetary science including the first light in the Universe (Cosmic Dawn), magnetic fields of extrasolar planets, particle acceleration mechanisms, and the lunar ionosphere. The Moon is a unique science platform because it allows access to radio frequencies that do not penetrate the Earth's ionosphere and because its far side is shielded from intense terrestrial emissions. A radio antenna can be realized by using polyimide film as a substrate, with a conducting substance deposited on it. Such an antenna can be rolled into a small volume for transport, then deployed by unrolling, and a robotic rover offers a natural means of unrolling a polyimide film-based antenna. An antenna deployment mechanism was developed that allows a thin film to be deposited onto a ground surface, in a controlled manner, using a minimally actuated rover. The deployment mechanism consists of two rollers, one driven and one passive. The antenna film is wrapped around the driven roller. The passive roller is mounted on linear bearings that allow it to move radially with respect to the driven roller. Springs preload the passive roller against the driven roller, and prevent the tightly wrapped film from unspooling or "bird's nesting" on the driven spool. The antenna deployment mechanism is integrated on the minimally-actuated Axel rover. Axel is a two-wheeled rover platform with a trailing boom that is capable of traversing undulated terrain and overcoming obstacles of a wheel radius in height. It is operated by four motors: one that drives each wheel; a third that controls the rotation of the boom, which orients the body mounted sensors; and a fourth that controls the rover's spool to drive the antenna roller. This low-mass axle-like rover houses its control and communication avionics inside its cylindrical body. The Axel rover teleoperation software has an auto-spooling mode that allows a user

  18. 47 CFR 101.517 - Antennas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antennas. 101.517 Section 101.517... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional, consistent with coverage and interference requirements. (b...

  19. 47 CFR 101.517 - Antennas.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Antennas. 101.517 Section 101.517... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional, consistent with coverage and interference requirements. (b...

  20. 47 CFR 73.816 - Antennas.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Antennas. 73.816 Section 73.816... Low Power FM Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only polarization, vertical only polarization, circular polarization or...

  1. 47 CFR 73.816 - Antennas.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Antennas. 73.816 Section 73.816... Low Power FM Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only polarization, vertical only polarization, circular polarization or...

  2. 47 CFR 73.816 - Antennas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antennas. 73.816 Section 73.816... Low Power FM Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only polarization, vertical only polarization, circular polarization or...

  3. 47 CFR 101.517 - Antennas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Antennas. 101.517 Section 101.517... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional, consistent with coverage and interference requirements. (b...

  4. 47 CFR 101.517 - Antennas.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Antennas. 101.517 Section 101.517... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional, consistent with coverage and interference requirements. (b...

  5. 47 CFR 73.816 - Antennas.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Antennas. 73.816 Section 73.816... Low Power FM Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only polarization, vertical only polarization, circular polarization or...

  6. 47 CFR 73.816 - Antennas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Antennas. 73.816 Section 73.816... Low Power FM Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only polarization, vertical only polarization, circular polarization or...

  7. 47 CFR 101.517 - Antennas.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Antennas. 101.517 Section 101.517... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional, consistent with coverage and interference requirements. (b...

  8. 2D radially compensating excitation pulse in combination with an internal transceiver antenna for 3D MRI of the rectum at 7 T.

    PubMed

    van Kalleveen, I M L; Kroeze, H; Sbrizzi, A; Boer, V O; Reerink, O; Philippens, M E P; van de Berg, C A T; Luijten, P R; Klomp, D W J

    2016-07-01

    The high precession frequency in ultrahigh field MRI coincides with reduced RF penetration, increased RF power deposition and consequently can lead to reduced scan efficiency. However, the shorter wavelength enables the use of efficient antennas rather than loop coils. In fact, ultrathin monopole antennas have been demonstrated at 7 T, which fit in natural cavities like the rectum in the human body. As the RF field generated by the antenna provides an extremely nonuniform B1 field, the use of conventional RF pulses will lead to severe image distortions and highly nonuniform contrast. However, using the two predominant dimensions (orthogonal to the antenna), 2D RF pulses can be designed that counteract the nonuniform B1 into uniform flip angles. In this study the authors investigate the use of an ultrathin antenna not only for reception, but also for transmission in 7 T MRI of the rectum. The 2D radially compensating excitation (2D RACE) pulse was designed in matlab. SAR calculations between the 2D RACE pulse and an adiabatic RF pulse (BIR-4) have been obtained, to visualize the gain in decreasing the SAR when using the 2D RACE pulse instead of an adiabatic RF pulse. The authors used the 7 T whole body MR system in combination with an internally placed monopole antenna used for transceiving and obtained 3D gradient echo images with a conventional sinc pulse and with the 2D RACE pulse. For extra clarity, they also reconstructed an image where the receive field of the antenna was removed. Comparing the results of the SAR simulations of the 2D RACE pulse with a BIR-4 pulse shows that for low flip angles (θ < 41°) the SAR can be decreased with a factor of 4.8 or even more, when using the 2D RACE pulse. Relative to a conventional sinc excitation, the 2D RACE pulse achieves more uniform flip angle distributions than a BIR-4 pulse with a smaller SAR increase (16 × versus 64 ×). The authors have shown that the 2D RACE pulse provides more homogeneous flip angles for

  9. An Accurate Method for Measuring Airplane-Borne Conformal Antenna's Radar Cross Section

    NASA Astrophysics Data System (ADS)

    Guo, Shuxia; Zhang, Lei; Wang, Yafeng; Hu, Chufeng

    2016-09-01

    The airplane-borne conformal antenna attaches itself tightly with the airplane skin, so the conventional measurement method cannot determine the contribution of the airplane-borne conformal antenna to its radar cross section (RCS). This paper uses the 2D microwave imaging to isolate and extract the distribution of the reflectivity of the airplane-borne conformal antenna. It obtains the 2D spatial spectra of the conformal antenna through the wave spectral transform between the 2D spatial image and the 2D spatial spectrum. After the interpolation from the rectangular coordinate domain to the polar coordinate domain, the spectral domain data for the variation of the scatter of the conformal antenna with frequency and angle is obtained. The experimental results show that the measurement method proposed in this paper greatly enhances the airplane-borne conformal antenna's RCS measurement accuracy, essentially eliminates the influences caused by the airplane skin and more accurately reveals the airplane-borne conformal antenna's RCS scatter properties.

  10. GPS Antenna Data Needed : GPS Adjacent Band Compatibility Workshop Volpe Center, Cambridge MA

    DOT National Transportation Integrated Search

    2014-09-18

    Topics. 1. Technical Objective: Receiver Antenna Mask and Electronics Data. 2. Definition of Receiver Antenna Mask. 3. Use of Receiver Antenna Mask. 4. Approaches to Generate the Antenna Mask. 5. Request for Receiver Antenna Data. 6. Next Steps.

  11. Analysis of a generalized dual reflector antenna system using physical optics

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.; Lagin, Alan R.

    1992-01-01

    Reflector antennas are widely used in communication satellite systems because they provide high gain at low cost. Offset-fed single paraboloids and dual reflector offset Cassegrain and Gregorian antennas with multiple focal region feeds provide a simple, blockage-free means of forming multiple, shaped, and isolated beams with low sidelobes. Such antennas are applicable to communications satellite frequency reuse systems and earth stations requiring access to several satellites. While the single offset paraboloid has been the most extensively used configuration for the satellite multiple-beam antenna, the trend toward large apertures requiring minimum scanned beam degradation over the field of view 18 degrees for full earth coverage from geostationary orbit may lead to impractically long focal length and large feed arrays. Dual reflector antennas offer packaging advantages and more degrees of design freedom to improve beam scanning and cross-polarization properties. The Cassegrain and Gregorian antennas are the most commonly used dual reflector antennas. A computer program for calculating the secondary pattern and directivity of a generalized dual reflector antenna system was developed and implemented at LeRC. The theoretical foundation for this program is based on the use of physical optics methodology for describing the induced currents on the sub-reflector and main reflector. The resulting induced currents on the main reflector are integrated to obtain the antenna far-zone electric fields. The computer program is verified with other physical optics programs and with measured antenna patterns. The comparison shows good agreement in far-field sidelobe reproduction and directivity.

  12. A Review of Antenna Technologies for Future NASA Exploration Missions

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Nessel, James A.; Romanofsky, Robert R.; Acostia, Roberto J.

    2006-01-01

    NASA s plans for the manned exploration of the Moon and Mars will rely heavily on the development of a reliable communications infrastructure from planetary surface-to-surface, surface-to-orbit and back to Earth. Future missions will thus focus not only on gathering scientific data, but also on the formation of the communications network. In either case, unique requirements become imposed on the antenna technologies necessary to accomplish these tasks. For example, proximity (i.e., short distance) surface activity applications such as robotic rovers, human extravehicular activities (EVA), and probes will require small size, lightweight, low power, multi-functionality, and robustness for the antenna elements being considered. In contrast, trunk-line communications to a centralized habitat on the surface and back to Earth (e.g., relays, satellites, and landers) will necessitate high gain, low mass antennas such as novel inflatable/deployable antennas. Likewise, the plethora of low to high data rate services desired to guarantee the safety and quality of mission data for robotic and human exploration will place additional demands on the technology. Over the last few years, NASA Glenn Research Center has been heavily involved in the development and evaluation of candidate antenna technologies with the potential for meeting the aforementioned requirements. These technologies range from electrically small antennas to phased arrays and large inflatable antenna structures. A summary of these efforts will be discussed in this paper. NASA planned activities under the Exploration Vision as they pertain to the communications architecture for the Lunar and Martian scenarios will be discussed, with emphasis on the desirable qualities of potential antenna element designs for envisioned communications assets. Identified frequency allocations for the Lunar and Martian surfaces, as well as asset-specific data services will be described to develop a foundation for viable antenna

  13. A Review of Antenna Technologies for Future NASA Exploration Missions

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Nessel, James A.; Romanofsky, Robert R.; Acosta, J.

    2007-01-01

    NASA's plans for the manned exploration of the Moon and Mars will rely heavily on the development of a reliable communications infrastructure from planetary surface-to-surface, surface-to-orbit and back to Earth. Future missions will thus focus not only on gathering scientific data, but also on the formation of the communications network. In either case, unique requirements become imposed on the antenna technologies necessary to accomplish these tasks. For example, proximity (i.e., short distance) surface activity applications such as robotic rovers, human extravehicular activities (EVA), and probes will require small size, lightweight, low power, multi-functionality, and robustness for the antenna elements being considered. In contrast, trunk-line communications to a centralized habitat on the surface and back to Earth (e.g., relays, satellites, and landers) will necessitate high gain, low mass antennas such as novel inflatable/deployable antennas. Likewise, the plethora of low to high data rate services desired to guarantee the safety and quality of mission data for robotic and human exploration will place additional demands on the technology. Over the last few years, NASA Glenn Research Center has been heavily involved in the development and evaluation of candidate antenna technologies with the potential for meeting the aforementioned requirements. These technologies range from electrically small antennas to phased arrays and large inflatable antenna structures. A summary of these efforts will be discussed in this paper. NASA planned activities under the Exploration Vision as they pertain to the communications architecture for the Lunar and Martian scenarios will be discussed, with emphasis on the desirable qualities of potential antenna element designs for envisioned communications assets. Identified frequency allocations for the Lunar and Martian surfaces, as well as asset-specific data services will be described to develop a foundation for viable antenna

  14. Proceedings of the Antenna Applications Symposium (1993). Volume 1

    DTIC Science & Technology

    1994-02-01

    Technology - Past and Future," by J. K. Schindler 2. * " Integrated Circuit Active Phased Array Antennas for Millimeter Wave Communications Applications...High Gain Antenna System has become the market leader in commercial aircraft installations. Two side-mounted phased arrays are employed on a single...production cost to be competitive in commercial markets . Antenna pattern and system performance are presented in this paper. 23 1.0 INTRODUCTION As

  15. Analysis of Microstrip Line Fed Patch Antenna for Wireless Communications

    NASA Astrophysics Data System (ADS)

    Singh, Ashish; Aneesh, Mohammad; Kamakshi; Ansari, J. A.

    2017-11-01

    In this paper, theoretical analysis of microstrip line fed rectangular patch antenna loaded with parasitic element and split-ring resonator is presented. The proposed antenna shows that the dualband operation depends on gap between parasitic element, split-ring resonator, length and width of microstrip line. It is found that antenna resonates at two distinct resonating modes i.e., 0.9 GHz and 1.8 GHz for lower and upper resonance frequencies respectively. The antenna shows dual frequency nature with frequency ratio 2.0. The characteristics of microstrip line fed rectangular patch antenna loaded with parasitic element and split-ring resonator antenna is compared with other prototype microstrip line fed antennas. Further, the theoretical results are compared with simulated and reported experimental results, they are in close agreement.

  16. An Antenna with Good Electrical Properties and Artistic Shape for Lampshade

    NASA Astrophysics Data System (ADS)

    Zhou, Chang; Yu, Yang; Ji, Chen

    2018-06-01

    An improved transparent antenna based on transparent ceramic MgAl2O4 with artistic shape which can be used as lampshade is presented in this paper. A great peak gain and good pattern can be achieved by choosing the property shape and optimizing location of the feed of the antenna. Simulation results indicate that this antenna can achieve return loss >-15dB, peak gain >8 dBi at 2 GHz and 40% relative impedance bandwidth. Both the electrical properties and artistic shape of the antenna are realized and the lampshade which made by MgAl2O4 meets the requirement for communication, decoration and high light transmission.

  17. Optimization of wearable microwave antenna with simplified electromagnetic model of the human body

    NASA Astrophysics Data System (ADS)

    Januszkiewicz, Łukasz; Barba, Paolo Di; Hausman, Sławomir

    2017-12-01

    In this paper the problem of optimization design of a microwave wearable antenna is investigated. Reference is made to a specific antenna design that is a wideband Vee antenna the geometry of which is characterized by 6 parameters. These parameters were automatically adjusted with an evolution strategy based algorithm EStra to obtain the impedance matching of the antenna located in the proximity of the human body. The antenna was designed to operate in the ISM (industrial, scientific, medical) band which covers the frequency range of 2.4 GHz up to 2.5 GHz. The optimization procedure used the finite-difference time-domain method based full-wave simulator with a simplified human body model. In the optimization procedure small movements of antenna towards or away of the human body that are likely to happen during real use were considered. The stability of the antenna parameters irrespective of the movements of the user's body is an important factor in wearable antenna design. The optimization procedure allowed obtaining good impedance matching for a given range of antenna distances with respect to the human body.

  18. 47 CFR 25.132 - Verification of earth station antenna performance standards.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Verification of earth station antenna... Verification of earth station antenna performance standards. (a)(1) Except for applications for 20/30 GHz earth... the antenna manufacturer on representative equipment in representative configurations, and the test...

  19. 47 CFR 15.203 - Antenna requirement.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Antenna requirement. 15.203 Section 15.203... Antenna requirement. An intentional radiator shall be designed to ensure that no antenna other than that furnished by the responsible party shall be used with the device. The use of a permanently attached antenna...

  20. 47 CFR 15.203 - Antenna requirement.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Antenna requirement. 15.203 Section 15.203... Antenna requirement. An intentional radiator shall be designed to ensure that no antenna other than that furnished by the responsible party shall be used with the device. The use of a permanently attached antenna...