Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems.

PubMed

Okabe, Kenji; Jeewan, Horagodage Prabhath; Yamagiwa, Shota; Kawano, Takeshi; Ishida, Makoto; Akita, Ippei

2015-12-16

In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 μm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction.

Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems

PubMed Central

Okabe, Kenji; Jeewan, Horagodage Prabhath; Yamagiwa, Shota; Kawano, Takeshi; Ishida, Makoto; Akita, Ippei

2015-01-01

In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 μm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction. PMID:26694407

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.

Review of Large Spacecraft Deployable Membrane Antenna Structures

NASA Astrophysics Data System (ADS)

Liu, Zhi-Quan; Qiu, Hui; Li, Xiao; Yang, Shu-Li

2017-11-01

The demand for large antennas in future space missions has increasingly stimulated the development of deployable membrane antenna structures owing to their light weight and small stowage volume. However, there is little literature providing a comprehensive review and comparison of different membrane antenna structures. Space-borne membrane antenna structures are mainly classified as either parabolic or planar membrane antenna structures. For parabolic membrane antenna structures, there are five deploying and forming methods, including inflation, inflation-rigidization, elastic ribs driven, Shape Memory Polymer (SMP)-inflation, and electrostatic forming. The development and detailed comparison of these five methods are presented. Then, properties of membrane materials (including polyester film and polyimide film) for parabolic membrane antennas are compared. Additionally, for planar membrane antenna structures, frame shapes have changed from circular to rectangular, and different tensioning systems have emerged successively, including single Miura-Natori, double, and multi-layer tensioning systems. Recent advances in structural configurations, tensioning system design, and dynamic analysis for planar membrane antenna structures are investigated. Finally, future trends for large space membrane antenna structures are pointed out and technical problems are proposed, including design and analysis of membrane structures, materials and processes, membrane packing, surface accuracy stability, and test and verification technology. Through a review of large deployable membrane antenna structures, guidance for space membrane-antenna research and applications is provided.

A finite element-boundary integral method for cavities in a circular cylinder

NASA Technical Reports Server (NTRS)

Kempel, Leo C.; Volakis, John L.

1992-01-01

Conformal antenna arrays offer many cost and weight advantages over conventional antenna systems. However, due to a lack of rigorous mathematical models for conformal antenna arrays, antenna designers resort to measurement and planar antenna concepts for designing non-planar conformal antennas. Recently, we have found the finite element-boundary integral method to be very successful in modeling large planar arrays of arbitrary composition in a metallic plane. We extend this formulation to conformal arrays on large metallic cylinders. In this report, we develop the mathematical formulation. In particular, we discuss the shape functions, the resulting finite elements and the boundary integral equations, and the solution of the conformal finite element-boundary integral system. Some validation results are presented and we further show how this formulation can be applied with minimal computational and memory resources.

Analysis of the stress-deformed condition of the disassembly parabolic antenna

NASA Astrophysics Data System (ADS)

Odinets, M. N.; Kaygorodtseva, N. V.; Krysova, I. V.

2018-01-01

Active development of satellite communications and computer-aided design systems raises the problem of designing parabolic antennas on a new round of development. The aim of the work was to investigate the influence of the design of the mirror of a parabolic antenna on its endurance under wind load. The research task was an automated analysis of the stress-deformed condition of various designs of computer models of a paraboloid mirror (segmented or holistic) at modeling the exploitation conditions. The peculiarity of the research was that the assembly model of the antenna’s mirror was subjected to rigid connections on the contacting surfaces of the segments and only then the finite element grid was generated. The analysis showed the advantage of the design of the demountable antenna, which consists of cyclic segments, in front of the construction of the holistic antenna. Calculation of the stress-deformed condition of the antennas allows us to conclude that dividing the design of the antenna’s mirror on parabolic and cyclic segments increases it strength and rigidity. In the future, this can be used to minimize the mass of antenna and the dimensions of the disassembled antenna. The presented way of modeling a mirror of a parabolic antenna using to the method of the finite-element analysis can be used in the production of antennas.

Aerogel-Based Antennas for Aerospace and Terrestrial Applications

NASA Technical Reports Server (NTRS)

Meador, Mary Ann (Inventor); Miranda, Felix (Inventor); Van Keuls, Frederick (Inventor)

2016-01-01

Systems and methods for lightweight, customizable antenna with improved performance and mechanical properties are disclosed. In some aspects, aerogels can be used, for example, as a substrate for antenna fabrication. The reduced weight and expense, as well as the increased ability to adapt antenna designs, permits a systems to mitigate a variety of burdens associated with antennas while providing added benefits.

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.

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

Phased Antenna Array for Global Navigation Satellite System Signals

NASA Technical Reports Server (NTRS)

Turbiner, Dmitry (Inventor)

2015-01-01

Systems and methods for phased array antennas are described. Supports for phased array antennas can be constructed by 3D printing. The array elements and combiner network can be constructed by conducting wire. Different parameters of the antenna, like the gain and directivity, can be controlled by selection of the appropriate design, and by electrical steering. Phased array antennas may be used for radio occultation measurements.

Demonstration of a directional sonic prism in two dimensions using an air-acoustic leaky wave antenna

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

Naify, Christina J., E-mail: christina.naify@nrl.navy.mil; Rohde, Charles A.; Calvo, David C.

Analysis and experimental demonstration of a two-dimensional acoustic leaky wave antenna is presented for use in air. The antenna is comprised of a two-dimensional waveguide patterned with radiating acoustic shunts. When excited using a single acoustic source within the waveguide, the antenna acts as a sonic prism that exhibits frequency steering. This design allows for control of acoustic steering angle using only a single source transducer and a patterned aperture. Aperture design was determined using transmission line analysis and finite element methods. The designed antenna was fabricated and the steering angle measured. The performance of the measured aperture was withinmore » 9% of predicted angle magnitudes over all examined frequencies.« less

Performance analysis and comparison of ITO- and FTO-based optically transparent terahertz U-shaped patch antennas

NASA Astrophysics Data System (ADS)

Thampy, Anand Sreekantan; Dhamodharan, Sriram Kumar

2015-02-01

An indium-doped tin oxide (ITO) and a fluorine-doped tin oxide (FTO)-based optically transparent U-shaped patch antennas are designed to resonate at 750 GHz and their performances are analyzed. Impedance bandwidth, radiation efficiency, directivity and gain of the proposed antennas are investigated. The proposed transparent antenna's characteristics are compared with the copper-based non-transparent U-shaped patch antenna, which is also designed to resonate at 750 GHz. Terahertz antennas are essential for inter-satellite communications systems to enable the adequate spatial resolution, broad bandwidth, higher data rates and highly directional beam with secured data transfer. The proposed ITO- and FTO-based transparent antennas have yielded impedance bandwidth of 9.54% and 11.49%, respectively, in the band 719-791 GHz and 714-801 GHz, respectively. The peak gain for ITO and FTO based transparent antennas is 3.35 dB and 2.26 dB at 732 GHz and 801 GHz, respectively. The proposed antennas are designed and simulated by using a finite element method based electromagnetic solver, Ansys - HFSS.

Design of microstrip patch antennas using knowledge insertion through retraining

NASA Astrophysics Data System (ADS)

Divakar, T. V. S.; Sudhakar, A.

2018-04-01

The traditional way of analyzing/designing neural network is to collect experimental data and train neural network. Then, the trained neural network acts as global approximate function. The network is then used to calculate parameters for unknown configurations. The main drawback of this method is one does not have enough experimental data, cost of prototypes being a major factor [1-4]. Therefore, in this method the author collected training data from available approximate formulas with in full design range and trained the network with it. After successful training, the network is retrained with available measured results. This simple way inserts experimental knowledge into the network [5]. This method is tested for rectangular microstrip antenna and circular microstrip antenna.

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 constrain the evolutionary design to a monopole wire antenna. The results of the runs produced requirements-compliant antennas that were subsequently fabricated and tested. The evolved antenna has a number of advantages with regard to power consumption, fabrication time and complexity, and performance. Lower power requirements result from achieving high gain across a wider range of elevation angles, thus allowing a broader range of angles over which maximum data throughput can be achieved. Since the evolved antenna does not require a phasing circuit, less design and fabrication work is required. In terms of overall work, the evolved antenna required approximately three person-months to design and fabricate whereas the conventional antenna required about five. Furthermore, when the mission was modified and new orbital parameters selected, a redesign of the antenna to new requirements was required. The evolutionary system was rapidly modified and a new antenna evolved in a few weeks. The evolved antenna was shown to be compliant to the ST5 mission requirements. It has an unusual organic looking structure, one that expert antenna designers would not likely produce. This antenna has been tested, baselined and is scheduled to fly this year. In addition to the ST5 antenna, our laboratory has evolved an S-band phased array antenna element design that meets the requirements for NASA's TDRS-C communications satellite scheduled for launch early next decade. A combination of fairly broad bandwidth, high efficiency and circular polarization at high gain made for another challenging design problem. We chose to constrain the evolutionary design to a crossed-element Yagi antenna. The 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 getic algorithm and stochastic hill-climbing has been fabricated and tested. Laboratory results correspond well with simulation. Aerospace component design is an expensive and important step in space development. Evolutionary design can make a significant contribution wherever sufficiently fast, accurate and capable software simulators are available. We have demonstrated successful real-world design in the spacecraft antenna domain; and there is good reason to believe that these results could be replicated in other design spaces.

Simulation Analysis of a Strip Dipole Excited Electromagnetic Band-Gap (EBG) Structure

DTIC Science & Technology

2015-07-01

unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The design of an Electromagnetic Band-Gap (EBG) for a particular antenna application is...summarized. Discussion is provided on interpretation of the EBG reflection coefficient phase for antenna applications and on the range of the EBG bandwidth...It is determined for antenna applications that the reflection phase and current design methods may be misleading. Instead, it is opinioned and shown

Condition monitoring of Electric Components

NASA Astrophysics Data System (ADS)

Zaman, Ishtiaque

A universal non-intrusive model of a flexible antenna array is presented in this paper to monitor and identify the failures in electric machines. This adjustable antenna is designed to serve the purpose of condition monitoring of a vast range of electrical components including Induction Motor (IM), Printed Circuit Board (PCB), Synchronous Reluctance Motor (SRM), Permanent Magnet Synchronous Machine (PMSM) etc. by capturing the low frequency magnetic field radiated around these machines. The basic design and specification of the proposed antenna array for low frequency components is portrayed first. The design of the antenna is adjustable to fit for an extensive variety of segments. Subsequent to distinguishing the design and specifications of the antenna, the ideal area of the most delicate stray field has been identified for healthy current streaming around the machineries. Following this, short circuit representing faulty situation has been introduced and compared with the healthy cases. Precision has been found recognizing the faults using this one generic model of Antenna and the results are presented for three different machines i.e. IM, SRM and PMSM. Finite element method has been used to design the antenna and detect the optimum location and faults in the machines. Finally, a 3D Printer is proposed to be employed to build the antenna as per the details tended to in this paper contingent upon the power segments.

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.

Analysis and synthesis of (SAR) waveguide phased array antennas

NASA Astrophysics Data System (ADS)

Visser, H. J.

1994-02-01

This report describes work performed due to ESA contract No. 101 34/93/NL/PB. Started is with a literature study on dual polarized waveguide radiators, resulting in the choice for the open ended square waveguide. After a thorough description of the mode matching infinite waveguide array analysis method - including finiteness effects - that forms the basis for all further described analysis and synthesis methods, the accuracy of the analysis software is validated by comparison with measurements on two realized antennas. These antennas have centered irises in the waveguide apertures and a dielectric wide angle impedance matching sheet in front of the antenna. A synthesis method, using simulated annealing and downhill simplex, is described next and different antenna designs, based on the analysis of a single element in an infinite array environment, are presented. Next, designs of subarrays are presented. Shown is the paramount importance of including the array environment in the design of a subarray. A microstrip patch waveguide exciter and subarray feeding network are discussed and the depth of the waveguide radiator is estimated. Chosen is a rectangular grid array with waveguides of 2.5 cm depth without irises and without dielectric sheet, grouped in linear 8 elements subarrays.

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

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

Scalability of surrogate-assisted multi-objective optimization of antenna structures exploiting variable-fidelity electromagnetic simulation models

NASA Astrophysics Data System (ADS)

Koziel, Slawomir; Bekasiewicz, Adrian

2016-10-01

Multi-objective optimization of antenna structures is a challenging task owing to the high computational cost of evaluating the design objectives as well as the large number of adjustable parameters. Design speed-up can be achieved by means of surrogate-based optimization techniques. In particular, a combination of variable-fidelity electromagnetic (EM) simulations, design space reduction techniques, response surface approximation models and design refinement methods permits identification of the Pareto-optimal set of designs within a reasonable timeframe. Here, a study concerning the scalability of surrogate-assisted multi-objective antenna design is carried out based on a set of benchmark problems, with the dimensionality of the design space ranging from six to 24 and a CPU cost of the EM antenna model from 10 to 20 min per simulation. Numerical results indicate that the computational overhead of the design process increases more or less quadratically with the number of adjustable geometric parameters of the antenna structure at hand, which is a promising result from the point of view of handling even more complex problems.

(DCT) A Reconfigurable RF Photonics Unit Cell For Integrated Circuits

DTIC Science & Technology

2012-08-10

Public Release In this work, the integration of a Quantum Dot Mode Locked Laser , that acts as a microwave and millimeter wave source, with a wideband...antenna is presented. Two aspects of research are discussed. The first aspect deals with a Mode Locked Laser (MLL) based on quantum dot (QD...designed antennas were integrated with laser chips using the lithographic method. The challenges of designing this wideband antenna that can operate

Design optimization of dual-axis driving mechanism for satellite antenna with two planar revolute clearance joints

NASA Astrophysics Data System (ADS)

Bai, Zheng Feng; Zhao, Ji Jun; Chen, Jun; Zhao, Yang

2018-03-01

In the dynamic analysis of satellite antenna dual-axis driving mechanism, it is usually assumed that the joints are ideal or perfect without clearances. However, in reality, clearances in joints are unavoidable due to assemblage, manufacturing errors and wear. When clearance is introduced to the mechanism, it will lead to poor dynamic performances and undesirable vibrations due to impact forces in clearance joint. In this paper, a design optimization method is presented to reduce the undesirable vibrations of satellite antenna considering clearance joints in dual-axis driving mechanism. The contact force model in clearance joint is established using a nonlinear spring-damper model and the friction effect is considered using a modified Coulomb friction model. Firstly, the effects of clearances on dynamic responses of satellite antenna are investigated. Then the optimization method for dynamic design of the dual-axis driving mechanism with clearance is presented. The objective of the optimization is to minimize the maximum absolute vibration peak of antenna acceleration by reducing the impact forces in clearance joint. The main consideration here is to optimize the contact parameters of the joint elements. The contact stiffness coefficient, damping coefficient and the dynamic friction coefficient for clearance joint elements are taken as the optimization variables. A Generalized Reduced Gradient (GRG) algorithm is used to solve this highly nonlinear optimization problem for dual-axis driving mechanism with clearance joints. The results show that the acceleration peaks of satellite antenna and contact forces in clearance joints are reduced obviously after design optimization, which contributes to a better performance of the satellite antenna. Also, the application and limitation of the proposed optimization method are discussed.

Novel method to control antenna currents based on theory of characteristic modes

NASA Astrophysics Data System (ADS)

Elghannai, Ezdeen Ahmed

Characteristic Mode Theory is one of the very few numerical methods that provide a great deal of physical insight because it allows us to determine the natural modes of the radiating structure. The key feature of these modes is that the total induced antenna current, input impedance/admittance and radiation pattern can be expressed as a linear weighted combination of individual modes. Using this decomposition method, it is possible to study the behavior of the individual modes, understand them and therefore control the antennas behavior; in other words, control the currents induced on the antenna structure. This dissertation advances the topic of antenna design by carefully controlling the antenna currents over the desired frequency band to achieve the desired performance specifications for a set of constraints. Here, a systematic method based on the Theory of Characteristic Modes (CM) and lumped reactive loading to achieve the goal of current control is developed. The lumped reactive loads are determined based on the desired behavior of the antenna currents. This technique can also be used to impedance match the antenna to the source/generator connected to it. The technique is much more general than the traditional impedance matching. Generally, the reactive loads that properly control the currents exhibit a combination of Foster and non-Foster behavior. The former can be implemented with lumped passive reactive components, while the latter can be implemented with lumped non-Foster circuits (NFC). The concept of current control is applied to design antennas with a wide band (impedance/pattern) behavior using reactive loads. We successfully applied this novel technique to design multi band and wide band antennas for wireless applications. The technique was developed to match the antenna to resistive and/or complex source impedance and control the radiation pattern at these frequency bands, considering size and volume constraints. A wide band patch antenna was achieved using the developed technique. In addition, the technique was applied to multi band wire less Universal Serial Bus (USB) dongle antenna that serves for WLAN IEEE 802.11 a/b/g/n band applications and Radio Frequency Identification (RFID) tag antenna for 915MHz band applications with superior performance compared to previous published results. This dissertation also discusses the total Q of an antenna from the CM standpoint. A new expression as well as additional physical information about each mode's individual contribution to the total antenna Q are provided. Finally, the theory is used to an analyze the antenna in both radiation and/or scattering modes. In the antenna scattering mode, the field scattered by an antenna contains a component that is the short circuit scattered field, and a second component that is proportional to the radiation field. In this dissertation, an analytical study of this phenomena from the CM standpoint is performed aiming to shed some light on antenna scattering phenomenon where additional physical insight is obtained and thus used to reach desire results.

W-Band On-Wafer Measurement of Uniplanar Slot-Type Antennas

NASA Technical Reports Server (NTRS)

Raman, Sanjay; Gauthier, Gildas P.; Rebeiz, Gabriel M.

1997-01-01

Uniplanar slot-type antennas such as coplanar waveguide fed single- and dual-polarized slot-ring antennas and double folded-slot antennas are characterized using a millimeter-wave network analyzer and on-wafer measurement techniques. The antennas are designed to be mounted on a dielectric lens to minimize power loss into substrate modes and realize high-gain antenna patterns. On-wafer measurements are performed by placing the antenna wafer on a thick dielectric spacer of similar e(sub t) and eliminating the reflection from the probe station chuck with time-domain gating. The measured results agree well with method-of-moments simulations.

Planar Dipole Input Resistance vs. Trace Thickness for Different Materials

DTIC Science & Technology

2014-09-01

adequate manufacturing methods such as inkjet printing.2 As such, good antenna construction requires careful consideration of design constraints, as well...antenna to be constructed from different materials and through different manufacturing methods, preferably inkjet printing. This report validates the...antenna for RFID applications. IEEE Xplore Digital Library (2014): n. pag. Web. 31 July 2014. 2. Rida A, Yang L, Vyas R, Tentzeris MM. Conductive inkjet

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.

Analysis of airborne antenna systems using geometrical theory of diffraction and moment method computer codes

NASA Technical Reports Server (NTRS)

Hartenstein, Richard G., Jr.

1985-01-01

Computer codes have been developed to analyze antennas on aircraft and in the presence of scatterers. The purpose of this study is to use these codes to develop accurate computer models of various aircraft and antenna systems. The antenna systems analyzed are a P-3B L-Band antenna, an A-7E UHF relay pod antenna, and traffic advisory antenna system installed on a Bell Long Ranger helicopter. Computer results are compared to measured ones with good agreement. These codes can be used in the design stage of an antenna system to determine the optimum antenna location and save valuable time and costly flight hours.

Antenna array geometry optimization for a passive coherent localisation system

NASA Astrophysics Data System (ADS)

Knott, Peter; Kuschel, Heiner; O'Hagan, Daniel

2012-11-01

Passive Coherent Localisation (PCL), also known as Passive Radar, making use of RF sources of opportunity such as Radio or TV Broadcasting Stations, Cellular Phone Network Base Stations, etc. is an advancing technology for covert operation because no active radar transmitter is required. It is also an attractive addition to existing active radar stations because it has the potential to discover low-flying and low-observable targets. The CORA (Covert Radar) experimental passive radar system currently developed at Fraunhofer-FHR features a multi-channel digital radar receiver and a circular antenna array with separate elements for the VHF- and the UHF-range and is used to exploit alternatively Digital Audio (DAB) or Video Broadcasting (DVB-T) signals. For an extension of the system, a wideband antenna array is being designed for which a new discone antenna element has been developed covering the full DVB-T frequency range. The present paper describes the outline of the system and the numerical modelling and optimisation methods applied to solve the complex task of antenna array design: Electromagnetic full wave analysis is required for the parametric design of the antenna elements while combinatorial optimization methods are applied to find the best array positions and excitation coefficients for a regular omni-directional antenna performance. The different steps are combined in an iterative loop until the optimum array layout is found. Simulation and experimental results for the current system will be shown.

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.

Novel Microstrip Patch Antennas with Frequency Agility, Polarization Reconfigurability, Dual Null Steering Capability and Phased Array Antenna with Beam Steering Performance

NASA Astrophysics Data System (ADS)

Babakhani, Behrouz

Nowadays the wireless communication technology is playing an important role in our daily life. People use wireless devices not only as a conventional communication device but also as tracking and navigation tool, web browsing tool, data storage and transfer tool and so for many other reasons. Based on the user demand, wireless communication engineers try to accommodate as many as possible wireless systems and applications in a single device and therefore, creates a multifunctional device. Antenna, as an integral part of any wireless communication systems, should also be evolved and adjusted with development of wireless transceiver systems. Therefore multifunctional antennas have been introduced to support and enhance the functionality on modern wireless systems. The main focus and contribution of this thesis is design of novel multifunctional microstrip antennas with frequency agility, polarization reconfigurablity, dual null steering capability and phased array antenna with beam steering performance. In this thesis, first, a wide bandwidth(1.10 GHz to 1.60 GHz) right-handed circularly polarized (RHCP) directional antenna for global positioning system (GPS) satellite receive application has been introduced which covers all the GPS bands starting from L1 to L5. This design consists of two crossed bow-tie dipole antennas fed with sequentially phase rotated feed network backed with an artificial high impedance surface (HIS) structure to generate high gain directional radiation patterns. This design shows good CP gain and axial ratio (AR) and wide beamwidth performance. Although this design has good radiation quality, the size and the weight can be reduced as future study. In the second design, a frequency agile antenna was developed which also covers the L-band (L1 to L5) satellite communication frequencies. This frequency agile antenna was designed and realized by new implementation of varactor diodes in the geometry of a circular patch antenna. Beside wide frequency agility (1.17 GHz to 1.58 GHz), full polarization reconfiguration was added to the design by controlling ports excitation of circular patch using RF switches (vertical linear, horizontal linear, right-handed circular polarization (RHCP) and left-handed circular polarization (LHCP)). This deign maintains good gain and radiation efficiency over the tunable range as well as acceptable co-polarization and cross-polarization separation for different polarizations. Since many communications applications require beam steering ability, in our third design, we designed and developed a linear phased array antenna using a modified version of our frequency agile polarization reconfigurable antenna for beam steering applications. This design offers wide frequency agility (1.50 GHz to 2.40 GHz), full polarization reconfiguration (vertical linear, horizontal linear, LHCP and RHCP) as well as beam steering of +/-52° and +/-28° at 1.5 GHz and 2.4 GHz, respectively. In this 1x4 array, the excitation magnitude and phase of each element was controlled by an analog beamforming feed network (BFN) for beam steering purposes. The required excitation for each element to steer the beam toward a desired location was calculated using projection matrix method (PMM) which uses measured active element pattern (AEP) as its input. This array antenna performance for frequency agility, radiation quality for each polarization and beam steering capability was obtained in the acceptable range. In the last design, the full spherical dual null steering capability of a triple mode circular microstrip patch antenna was investigated. By combining the radiation patterns of three individual modes of microstrip circular patch antenna, two nulls have been generated. These nulls can be repositioned in the upper hemisphere by controlling excitation ratio of each mode. The modes excitation ratio to steer the nulls toward the desired positions was calculated using a derivative free hybrid optimization method. This optimization method uses particle swarm optimization (PSO) combined with pattern search (PS) to find the optimum modes excitation ratio which minimizes the received power at the null positions. The calculated coefficients were applied to the multimode antenna using an analog BFN. This design shows an independent dual null steering with null depth of around 20 dB. Discussion about the proposed antennas included detailed theoretical analysis, numerical simulation and optimizations, beam forming and null steering algorithms, fabrication of the antennas and its control/beamforming feed networks along with the associated bias networks, microcontroller units, and finally its characterization (impedance matching, gain and 2D and 3D radiation patterns). The research work was performed at the Antenna and Microwave Lab (AML) which has the required resources including full wave analysis tools, PCB milling machine, surface mount component soldering station, vector network analyzers, and far-field/spherical near-field radiation pattern measurement system.

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.

Robust Hybrid Finite Element Methods for Antennas and Microwave Circuits

NASA Technical Reports Server (NTRS)

Gong, J.; Volakis, John L.

1996-01-01

One of the primary goals in this dissertation is concerned with the development of robust hybrid finite element-boundary integral (FE-BI) techniques for modeling and design of conformal antennas of arbitrary shape. Both the finite element and integral equation methods will be first overviewed in this chapter with an emphasis on recently developed hybrid FE-BI methodologies for antennas, microwave and millimeter wave applications. The structure of the dissertation is then outlined. We conclude the chapter with discussions of certain fundamental concepts and methods in electromagnetics, which are important to this study.

A technology development program for large space antennas

NASA Technical Reports Server (NTRS)

Russell, R. A.; Campbell, T. G.; Freeland, R. E.

1980-01-01

The design and application of the offset wrap rib and the maypole (hoop/column) antenna configurations are described. The NASA mission model that generically categorizes the classes of user requirements, as well as the methods used to determine critical technologies and requirements are discussed. Performance estimates for the mesh deployable antenna selected for development are presented.

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 the forward gain. This antenna had the same impedance bandwidth of 10:1 while pattern bandwidth has been raised to 7:1. In antenna 3, a loop loaded bowtie antenna has been designed. This antenna do not employ any kind of resistive loading, yet achieves an impedance bandwidth of 11:1 and also a usable bandwidth of 11:1. The antenna 4 employs concentric offset loops which acts as directors to improve the directivity. This antenna achieved an impedance bandwidth and a pattern bandwidth of 13:1. All the antennas have a maximum size of about 0.3λ at lowest operating frequency. An experimental stepped frequency type GPR has been constructed to study the suitability of the fabricated antennas in detecting buried targets. Four experiments have been conducted viz. 1.) To detect a metallic pipe of 1in diameter, 2.) To detect a metallic pipe of 2in diameter 3.) To detect dry bamboo, 3.) To detect rebar in concrete. The detectability and imaging capability of GPR has been found to be improving from antenna 1 to 4.

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.

On the design and optimisation of new fractal antenna using PSO

NASA Astrophysics Data System (ADS)

Rani, Shweta; Singh, A. P.

2013-10-01

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

Synthetic aperture radar range - Azimuth ambiguity design and constraints

NASA Technical Reports Server (NTRS)

Mehlis, J. G.

1980-01-01

Problems concerning the design of a system for mapping a planetary surface with a synthetic aperture radar (SAR) are considered. Given an ambiguity level, resolution, and swath width, the problems are related to the determination of optimum antenna apertures and the most suitable pulse repetition frequency (PRF). From the set of normalized azimuth ambiguity ratio curves, the designer can arrive at the azimuth antenna length, and from the sets of normalized range ambiguity ratio curves, he can arrive at the range aperture length or pulse repetition frequency. A procedure based on this design method is shown in an example. The normalized curves provide results for a SAR using a uniformly or cosine weighted rectangular antenna aperture.

Direction Finding Using an Antenna with Direction Dependent Impulse Response

NASA Technical Reports Server (NTRS)

Foltz, Heinrich; Kegege, Obadiah

2016-01-01

Wideband antennas may be designed to have an impulse response that is direction dependent, not only in amplitude but also in waveform shape. This property can be used to perform direction finding using a single fixed antenna, without the need for an array or antenna rotation. In this paper direction finding is demonstrated using a simple candelabra-shaped monopole operating in the 1-3 GHz range. The method requires a known transmitted pulse shape and high signal-to-noise ratio, and is not as accurate or robust as conventional methods. However, it can add direction finding capability to a wideband communication system without the addition of any hardware.

Analysis of heating, ventilation, and air conditioning ducts as a radio frequency communication channel

NASA Astrophysics Data System (ADS)

Nikitin, Pavel Viktorovich

2002-01-01

A typical HVAC duct system is a network of interconnected hollow metal pipes which can serve as waveguides and carry electromagnetic waves. This work presents an analysis of this system as a radio frequency communication channel. Two main parts of the analysis include channel modelling and antenna design. The propagation modelling approach used here is based on the waveguide mode theory and employs the transfer matrix method to describe propagation through various cascaded HVAC elements. This allows one to model the channel response in the frequency domain. Impulse response characteristics of the ducts are also analyzed in this work. The approximate transfer matrices of cylindrical straight sections, bends, and tapers are derived analytically. The transforming properties of cylindrical T-junctions are analyzed experimentally. Antenna designs in waveguides and free-space are different. In waveguides, mode excitation characteristics are important as well as the impedance match. The criteria for antenna design in waveguides are presented here. Antennas analyzed in this work are monopole antennas, dipole antennas, and antenna arrays. The developed model can predict both channel response and antenna characteristics for a given geometry and dimensions of the duct system and the antennas. The model is computationally efficient and can potentially be applied to duct systems of multiple story buildings. The accuracy of the model has been validated with extensive experimental measurements on real HVAC ducts.

Control of small phased-array antennas

NASA Technical Reports Server (NTRS)

Doland, G. D.

1978-01-01

Series of reports, patent descriptions, calculator programs, and other literature describes antenna control and steering apparatus for seven-element phased array. Though series contains information specific to particular system, it illustrates methods that can be applied to antennas with greater or fewer numbers of elements. Included are programs for calculating beam parameters and design functions and information to interfacing digital controller to beam-steering apparatus.

The design and simulation of UHF RFID microstrip antenna

NASA Astrophysics Data System (ADS)

Chen, Xiangqun; Huang, Rui; Shen, Liman; Liu, Liping; Xiong, Dezhi; Xiao, Xiangqi; Liu, Mouhai; Renheng, Xu

2018-02-01

At present, China has delineated UHF RFID communicating frequency range which is 840 ∼ 845 MHz and 920 ∼ 925 MHz, but most UHF microstrip antenna don’t carry out this standard, that leads to radio frequency pollution. In order to solve the problems above, a method combining theory and simulation is adopted. Combining with a new ceramic material, a 925.5 MHz RFID microstrip antenna is designed, which is optimized and simulated by HFSS software. The results show that the VSWR of this RFID microstrip antenna is relatively small in the vicinity of 922.5 MHz, the gain is 2.1 dBi, which can be widely used in China’s UHF RFID communicating equipments.

Transmitter and receiver antenna gain analysis for laser radar and communication systems

NASA Technical Reports Server (NTRS)

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

1973-01-01

A comprehensive and fairly self-contained study of centrally obscured optical transmitting and receiving antennas is presented and is intended for use by the laser radar and communication systems designer. The material is presented in a format which allows the rapid and accurate evaluation of antenna gain. The Fresnel approximation to scalar wave theory is reviewed and the antenna analysis proceeds in terms of the power gain. Conventional range equations may then be used to calculate the power budget. The transmitter calculations, resulting in near and far field antenna gain patterns, assumes the antenna is illuminated by a laser operating in the fundamental cavity mode. A simple 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 which display the losses in antenna gain due to pointing errors and the cone angle of the outgoing beam as a function of antenna size and central obscuration. The use of telescope defocusing as an approach to spreading the beam for target acquisition is compared to some alternate methods.

Design of a dual linear polarization antenna using split ring resonators at X-band

NASA Astrophysics Data System (ADS)

Ahmed, Sadiq; Chandra, Madhukar

2017-11-01

Dual linear polarization microstrip antenna configurations are very suitable for high-performance satellites, wireless communication and radar applications. This paper presents a new method to improve the co-cross polarization discrimination (XPD) for dual linear polarized microstrip antennas at 10 GHz. For this, three various configurations of a dual linear polarization antenna utilizing metamaterial unit cells are shown. In the first layout, the microstrip patch antenna is loaded with two pairs of spiral ring resonators, in the second model, a split ring resonator is placed between two microstrip feed lines, and in the third design, a complementary split ring resonators are etched in the ground plane. This work has two primary goals: the first is related to the addition of metamaterial unit cells to the antenna structure which permits compensation for an asymmetric current distribution flow on the microstrip antenna and thus yields a symmetrical current distribution on it. This compensation leads to an important enhancement in the XPD in comparison to a conventional dual linear polarized microstrip patch antenna. The simulation reveals an improvement of 7.9, 8.8, and 4 dB in the E and H planes for the three designs, respectively, in the XPD as compared to the conventional dual linear polarized patch antenna. The second objective of this paper is to present the characteristics and performances of the designs of the spiral ring resonator (S-RR), split ring resonator (SRR), and complementary split ring resonator (CSRR) metamaterial unit cells. The simulations are evaluated using the commercial full-wave simulator, Ansoft High-Frequency Structure Simulator (HFSS).

Antenna pattern interpolation by generalized Whittaker reconstruction

NASA Astrophysics Data System (ADS)

Tjonneland, K.; Lindley, A.; Balling, P.

Whittaker reconstruction is an effective tool for interpolation of band limited data. Whittaker originally introduced the interpolation formula termed the cardinal function as the function that represents a set of equispaced samples but has no periodic components of period less than twice the sample spacing. It appears that its use for reflector antennas was pioneered in France. The method is now a useful tool in the analysis and design of multiple beam reflector antenna systems. A good description of the method has been given by Bucci et al. This paper discusses some problems encountered with the method and their solution.

Analysis of resonance response performance of C-band antenna using parasitic element.

PubMed

Zaman, M R; Islam, M T; Misran, N; Mandeep, J S

2014-01-01

Analysis of the resonance response improvement of a planar C-band (4-8 GHz) antenna is proposed using parasitic element method. This parasitic element based method is validated for change in the active and parasitic antenna elements. A novel dual-band antenna for C-band application covering 5.7 GHz and 7.6 GHz is designed and fabricated. The antenna is composed of circular parasitic element with unequal microstrip lines at both sides and a rectangular partial ground plane. A fractional bandwidth of 13.5% has been achieved from 5.5 GHz to 6.3 GHz (WLAN band) for the lower band. The upper band covers from 7.1 GHz to 8 GHz with a fractional bandwidth of 12%. A gain of 6.4 dBi is achieved at the lower frequency and 4 dBi is achieved at the upper frequency. The VSWR of the antenna is less than 2 at the resonance frequency.

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.

Using EIGER for Antenna Design and Analysis

NASA Technical Reports Server (NTRS)

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

2007-01-01

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

Model of the Radio Frequency (RF) Excitation Response from Monopole and Dipole Antennas in a Large Scale Tank

NASA Technical Reports Server (NTRS)

Wilson, Jeffrey D.; Zimmerli, Gregory A.

2012-01-01

Good antenna-mode coupling is needed for determining the amount of propellant in a tank through the method of radio frequency mass gauging (RFMG). The antenna configuration and position in a tank are important factors in coupling the antenna to the natural electromagnetic modes. In this study, different monopole and dipole antenna mounting configurations and positions were modeled and responses simulated in a full-scale tank model with the transient solver of CST Microwave Studio (CST Computer Simulation Technology of America, Inc.). The study was undertaken to qualitatively understand the effect of antenna design and placement within a tank on the resulting radio frequency (RF) tank spectrum.

Raft and floating radio frequency identification (RFID) antenna systems for detecting and estimating abundance of PIT-tagged fish in rivers

USGS Publications Warehouse

Fetherman, Eric R.; Avila, Brian W.; Winkelman, Dana L.

2016-01-01

Portable radio frequency identification (RFID) PIT tag antenna systems are increasingly being used in studies examining aquatic animal movement, survival, and habitat use, and their design flexibility permits application in a wide variety of settings. We describe the construction, use, and performance of two portable floating RFID PIT tag antenna systems designed to detect fish that were unavailable for recapture using stationary antennas or electrofishing. A raft antenna system was designed to detect and locate PIT-tagged fish in relatively long (i.e., ≥10 km) river reaches, and consisted of two antennas: (1) a horizontal antenna (4 × 1.2 m) installed on the bottom of the raft and used to detect fish in shallower river reaches (<1 m), and (2) a vertical antenna (2.7 × 1.2 m) for detecting fish in deeper pools (≥1 m). Detection distances of the horizontal antenna were between 0.7 and 1.0 m, and detection probability was 0.32 ± 0.02 (mean ± SE) in a field test using rocks marked with 32-mm PIT tags. Detection probability of PIT-tagged fish in the Cache la Poudre River, Colorado, using the raft antenna system, which covered 21% of the wetted area, was 0.14 ± 0.14. A shore-deployed floating antenna (14.6 × 0.6 m), which covered 100% of the wetted area, was designed for use by two operators for detecting and locating PIT-tagged fish in shorter (i.e., <2 km) river reaches. Detection distances of the shore-deployed floating antenna were between 0.7 and 0.8 m, and detection probabilities during field deployment in the St. Vrain River exceeded 0.52. The shore-deployed floating antenna was also used to estimate abundance of PIT-tagged fish. Results suggest that the shore-deployed floating antenna could be used as an alternative to estimating abundance using traditional sampling methods such as electrofishing.

Temperature field simulation and phantom validation of a Two-armed Spiral Antenna for microwave thermotherapy.

PubMed

Du, Yongxing; Zhang, Lingze; Sang, Lulu; Wu, Daocheng

2016-04-29

In this paper, an Archimedean planar spiral antenna for the application of thermotherapy was designed. This type of antenna was chosen for its compact structure, flexible application and wide heating area. The temperature field generated by the use of this Two-armed Spiral Antenna in a muscle-equivalent phantom was simulated and subsequently validated by experimentation. First, the specific absorption rate (SAR) of the field was calculated using the Finite Element Method (FEM) by Ansoft's High Frequency Structure Simulation (HFSS). Then, the temperature elevation in the phantom was simulated by an explicit finite difference approximation of the bioheat equation (BHE). The temperature distribution was then validated by a phantom heating experiment. The results showed that this antenna had a good heating ability and a wide heating area. A comparison between the calculation and the measurement showed a fair agreement in the temperature elevation. The validated model could be applied for the analysis of electromagnetic-temperature distribution in phantoms during the process of antenna design or thermotherapy experimentation.

An XML-based method for astronomy software designing

NASA Astrophysics Data System (ADS)

Liao, Mingxue; Aili, Yusupu; Zhang, Jin

XML-based method for standardization of software designing is introduced and analyzed and successfully applied to renovating the hardware and software of the digital clock at Urumqi Astronomical Station. Basic strategy for eliciting time information from the new digital clock of FT206 in the antenna control program is introduced. By FT206, the need to compute how many centuries passed since a certain day with sophisticated formulas is eliminated and it is no longer necessary to set right UT time for the computer holding control over antenna because the information about year, month, day are all deduced from Julian day dwelling in FT206, rather than from computer time. With XML-based method and standard for software designing, various existing designing methods are unified, communications and collaborations between developers are facilitated, and thus Internet-based mode of developing software becomes possible. The trend of development of XML-based designing method is predicted.

Radiation and scattering from cylindrically conformal printed antennas. Ph.D. Thesis Final Report

NASA Technical Reports Server (NTRS)

Kempel, Leo C.; Volakis, John L.

1994-01-01

Microstrip patch antennas offer considerable advantages in terms of weight, aerodynamic drag, cost, flexibility, and observables over more conventional protruding antennas. These flat patch antennas were first proposed over thirty years ago by Deschamps in the United States and Gutton and Baisinot in France. Such antennas have been analyzed and developed for planar as well as curved platforms. However, the methods used in these designs employ gross approximations, suffer from extreme computational burden, or require expensive physical experiments. The goal of this thesis is to develop accurate and efficient numerical modeling techniques which represent actual antenna structures mounted on curved surfaces with a high degree of fidelity. In this thesis, the finite element method is extended to cavity-backed conformal antenna arrays embedded in a circular, metallic, infinite cylinder. Both the boundary integral and absorbing boundary mesh closure conditions will be used for terminating the mesh. These two approaches will be contrasted and used to study the scattering and radiation behavior of several useful antenna configurations. An important feature of this study will be to examine the effect of curvature and cavity size on the scattering and radiation properties of wraparound conformal antenna arrays.

Broadband metamaterial lens antennas with special properties by controlling both refractive-index distribution and feed directivity

NASA Astrophysics Data System (ADS)

Ma, Qian; Shi, Chuan Bo; Chen, Tian Yi; Qing Qi, Mei; Li, Yun Bo; Cui, Tie Jun

2018-04-01

A new method is proposed to design gradient refractive-index metamaterial lens antennas by optimizing both the refractive-index distribution of the lens and the feed directivity. Comparing to the conventional design methods, source optimization provides a new degree of freedom to control aperture fields effectively. To demonstrate this method, two lenses with special properties based on this method are designed, to emit high-efficiency plane waves and fan-shaped beams, respectively. Both lenses have good performance and wide frequency band from 12 to 18 GHz, verifying the validity of the proposed method. The plane-wave emitting lens realized a high aperture efficiency of 75%, and the fan-beam lens achieved a high gain of 15 dB over board bandwidth. The experimental results have good agreement with the design targets and full-wave simulations.

Measurement of LHCD antenna position in Aditya tokamak

NASA Astrophysics Data System (ADS)

Ambulkar, K. K.; Sharma, P. K.; Virani, C. G.; Parmar, P. R.; Thakur, A. L.; Kulkarni, S. V.

2010-02-01

To drive plasma current non-inductively in ADITYA tokamak, 120 kW pulsed Lower Hybrid Current Drive (LHCD) system at 3.7 GHz has been designed, fabricated and installed on ADITYA tokamak. In this system, the antenna consists of a grill structure, having two rows, each row comprising of four sub-waveguides. The coupling of LHCD power to the plasma strongly depends on the plasma density near the mouth of grill antenna. Thus the grill antenna has to be precisely positioned for efficient coupling. The movement of mechanical bellow, which contracts or expands up to 50mm, governs the movement of antenna. In order to monitor the position of the antenna precisely, the reference position of the antenna with respect to the machine/plasma position has to be accurately determined. Further a mechanical system or an electronic system to measure the relative movement of the antenna with respect to the reference position is also desired. Also due to poor accessibility inside the ADITYA machine, it is impossible to measure physically the reference position of the grill antenna with respect to machine wall, taken as reference position and hence an alternative method has to be adopted to establish these measurements reliably. In this paper we report the design and development of a mechanism, using which the antenna position measurements are made. It also describes a unique method employing which the measurements of the reference position of the antenna with respect to the inner edge of the tokamak wall is carried out, which otherwise was impossible due to poor accessibility and physical constraints. The position of the antenna is monitored using an electronic scale, which is developed and installed on the bellow. Once the reference position is derived, the linear potentiometer, attached to the bellow, measures the linear distance using position transmitter. The accuracy of measurement obtained in our setup is within +/- 0.5 % and the linearity, along with repeatability is excellent.

Investigation of high temperature antennas for space shuttle

NASA Technical Reports Server (NTRS)

Kuhlman, E. A.

1973-01-01

The design and development of high temperature antennas for the space shuttle orbiter are discussed. The antenna designs were based on three antenna types, an annular slot (L-Band), a linear slot (C-Band), and a horn (C-Band). The design approach was based on combining an RF window, which provides thermal protection, with an off-the-shelf antenna. Available antenna window materials were reviewed and compared, and the materials most compatible with the design requirements were selected. Two antenna window design approaches were considered: one employed a high temperature dielectric material and a low density insulation material, and the other an insulation material usable for the orbiter thermal protection system. Preliminary designs were formulated and integrated into the orbiter structure. Simple electrical models, with a series of window configurations, were constructed and tested. The results of tests and analyses for the final antenna system designs are given and show that high temperature antenna systems consisting of off-the-shelf antennas thermally protected by RF windows can be designed for the Space Shuttle Orbiter.

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.

Structural dynamics analysis

NASA Technical Reports Server (NTRS)

Housner, J. M.; Anderson, M.; Belvin, W.; Horner, G.

1985-01-01

Dynamic analysis of large space antenna systems must treat the deployment as well as vibration and control of the deployed antenna. Candidate computer programs for deployment dynamics, and issues and needs for future program developments are reviewed. Some results for mast and hoop deployment are also presented. Modeling of complex antenna geometry with conventional finite element methods and with repetitive exact elements is considered. Analytical comparisons with experimental results for a 15 meter hoop/column antenna revealed the importance of accurate structural properties including nonlinear joints. Slackening of cables in this antenna is also a consideration. The technology of designing actively damped structures through analytical optimization is discussed and results are presented.

Computer-Automated Evolution of Spacecraft X-Band Antennas

NASA Technical Reports Server (NTRS)

Lohn, Jason D.; Homby, Gregory S.; Linden, Derek S.

2010-01-01

A document discusses the use of computer- aided evolution in arriving at a design for X-band communication antennas for NASA s three Space Technology 5 (ST5) satellites, which were launched on March 22, 2006. Two evolutionary algorithms, incorporating different representations of the antenna design and different fitness functions, were used to automatically design and optimize an X-band antenna design. A set of antenna designs satisfying initial ST5 mission requirements was evolved by use these algorithms. The two best antennas - one from each evolutionary algorithm - were built. During flight-qualification testing of these antennas, the mission requirements were changed. After minimal changes in the evolutionary algorithms - mostly in the fitness functions - new antenna designs satisfying the changed mission requirements were evolved and within one month of this change, two new antennas were designed and prototypes of the antennas were built and tested. One of these newly evolved antennas was approved for deployment on the ST5 mission, and flight-qualified versions of this design were built and installed on the spacecraft. At the time of writing the document, these antennas were the first computer-evolved hardware in outer space.

Analysis of a log periodic nano-antenna for multi-resonant broadband field enhancement and the Purcell factor

NASA Astrophysics Data System (ADS)

Yang, Jie; Kong, Fanmin; Li, Kang; Sheng, Shiwei

2015-05-01

Broadband nano-antennas play a central role in many areas of science and technology. However, a more intuitive understanding for rational design of nano-antennas with broadband response is desirable. A log periodic nano-antenna was studied in the paper. The finite-difference time-domain method was used to explore the spectral characteristics of the log periodic nano-antenna by the excitation mode of reception and emission. The effects of geometry on field enhancement and the Purcell factor were systematically described and investigated. The field enhancement of the nano-antenna can be tuned by geometric parameters such as the outer radius, the tooth angle, and the ratio of the radial sizes of successive teeth, which provide control over both the spectral resonance position and the field enhancement peak amplitude. The Purcell factor mainly depends on the outer radius, the tooth angle, and the bow angle. In addition, multi-resonant field enhancement was analyzed in detail by conformal transformation. Furthermore, a careful comparison of the characteristics of a bowtie nano-antenna demonstrated that the log periodic nano-antenna has considerable potential for multi-resonant field enhancement and improvement of the Purcell factor. The results provide a promising prospect for designing and optimizing the log periodic nano-antenna in a broad range of wavelengths.

Hybrid antenna arrays with non-uniform Electromagnetic Band Gap lattices for wireless communication networks

NASA Astrophysics Data System (ADS)

Mourtzios, Ch.; Siakavara, K.

2015-08-01

A method to design hybrid antenna configurations with very low profile, suitable for smart and Multiple Input-Multiple Output antenna systems is proposed. The antennas are incorporated with novel Electromagnetic Band Gap (EBG) surfaces with non-similar cells. These non-uniform EBG surfaces have been properly designed to cause focusing, of the incident waves, thus enhancing the characteristics of operation of antenna elements positioned in close proximity to the surface and also to increase the isolation between them. Theoretical analysis of the reflection mechanism of this type of lattices as well as the prediction of the resulting performance of the antenna is presented. All these considerations are validated with implementation and simulation of the hybrid structures inside the Universal Mobile Telecommunications System frequency band. The results show that increment of the gain and isolation between the antenna elements can be obtained. Moreover, results for the correlation coefficient between the elements, for Gaussian distribution of the incoming waves have been received and the tolerance of the antennas to the variation of the polarization characteristics of the incoming waves has been investigated. A Genetic Algorithm has been constructed and applied to find the proper geometry of the hybrid antennas in order the correlation coefficient to be minimized and get almost independent from the polarization of incident waves.

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 energy and recently reported work on antenna Q factor minimization, we extend the minimum Q limit to antennas of arbitrary geometry, and show that given an antenna aperture, any antenna design based on its substructure will result into minimum Q factors larger than or equal to that of the complete structure. This limit is much tighter than Chu's limit based on spherical modes, and applies to antennas of arbitrary geometry. Finally, considering the almost inevitable presence of mutual coupling effects within compact multiport antennas, we develop new decoupling networks (DN) and decoupling network synthesis techniques. An information-theoretic metric, information mismatch loss (Gammainfo), is defined for DN characterization. Based on this metric, the optimization of decoupling networks for broadband system performance is conducted, which demonstrates the limitation of the single-frequency decoupling techniques and room for improvement.

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.

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

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

Wideband monolithically integrated front-end subsystems and components

NASA Astrophysics Data System (ADS)

Mruk, Joseph Rene

This thesis presents the analysis, design, and measurements of passive, monolithically integrated, wideband recta-coax and printed circuit board front-end components. Monolithic fabrication of antennas, impedance transformers, filters, and transitions lowers manufacturing costs by reducing assembly time and enhances performance by removing connectors and cabling between the devices. Computational design, fabrication, and measurements are used to demonstrate the capabilities of these front-end assemblies. Two-arm wideband planar log-periodic antennas fed using a horizontal feed that allows for filters and impedance transformers to be readily fabricated within the radiating region of the antenna are demonstrated. At microwave frequencies, low-cost printed circuit board processes are typically used to produce planar devices. A 1.8 to 11 GHz two-arm planar log-periodic antenna is designed with a monolithically integrated impedance transformer. Band rejection methods based on modifying the antenna aperture, use of an integrated filter, and the application of both methods are investigated with realized gain suppressions of over 25 dB achieved. The ability of standard circuit board technology to fabricate millimeter-wave devices up to 110 GHz is severely limited. Thin dielectrics are required to prevent the excitation of higher order modes in the microstrip substrate. Fabricating the thin line widths required for the antenna aperture also becomes prohibitively challenging. Surface micro-machining typically used in the fabrication of MEMS devices is capable of producing the extremely small features that can be used to fabricate antennas extending through W-band. A directly RF fed 18 to 110 GHz planar log-periodic antenna is developed. The antenna is fabricated with an integrated impedance transformer and additional transitions for measurement characterization. Singly terminated low-loss wideband millimeter-wave filters operating over V- and W- band are developed. High quality performance of an 18 to 100 GHz front-end is realized by dividing the single instantaneous antenna into two apertures operating from 18 to 50 and 50 to 100 GHz. Each channel features an impedance transformer, low-pass (low-frequency) or band-pass (high-frequency) filter, and grounded CPW launch. This dual-aperture front-end demonstrates that micromachining technology is now capable of fabricating broadband millimeter-wave components with a high degree of integration.

Analysis of Resonance Response Performance of C-Band Antenna Using Parasitic Element

PubMed Central

Islam, M. T.; Misran, N.; Mandeep, J. S.

2014-01-01

Analysis of the resonance response improvement of a planar C-band (4–8 GHz) antenna is proposed using parasitic element method. This parasitic element based method is validated for change in the active and parasitic antenna elements. A novel dual-band antenna for C-band application covering 5.7 GHz and 7.6 GHz is designed and fabricated. The antenna is composed of circular parasitic element with unequal microstrip lines at both sides and a rectangular partial ground plane. A fractional bandwidth of 13.5% has been achieved from 5.5 GHz to 6.3 GHz (WLAN band) for the lower band. The upper band covers from 7.1 GHz to 8 GHz with a fractional bandwidth of 12%. A gain of 6.4 dBi is achieved at the lower frequency and 4 dBi is achieved at the upper frequency. The VSWR of the antenna is less than 2 at the resonance frequency. PMID:24895643

Analysis of Transient Electromagnetic Scattering from Three Dimensional Cavities

DTIC Science & Technology

2014-01-01

New York, 2002. [24] J. Jin and J. L. Volakis, A hybrid finite element method for scattering and radiation by micro strip patch antennas and arrays...applications such as the design of cavity-backed conformal antennas and the deliberate control in the form of enhancement or reduction of radar cross...electromagnetic scattering analysis, IEEE Trans. Antennas Propagat., 50 (2002), pp. 1192–1202. [22] J. Jin, Electromagnetic scattering from large, deep, and

Circuit Methods for VLF Antenna Couplers. [for use in Loran or Omega receiver systems

NASA Technical Reports Server (NTRS)

Burhans, R. W.

1977-01-01

The limitations of different E-field antenna coupler or preamplifier circuits are presented. All circuits were evaluated using actual Loran or Omega signals. Electric field whip or wire antennas are the simplest types which can be used for reception of VLF signals in the 10 to 100 kHz range. JFET or MOSFET transistors provide impedance transformation and some voltage gain in simple circuits where the power for operating the preamplifier uses the same coaxial cable that feeds the signal back to the receiver. The circuit techniques provide useful alternative methods for Loran-Omega receiver system designers.

A Method for Producing a Shaped Contour Radiation Pattern Using a Single Shaped Reflector and a Single Feed

NASA Technical Reports Server (NTRS)

Cherrette, A. R.; Lee, S. W.; Acosta, R. J.

1988-01-01

Eliminating the corporate feed network in shaped contour beam antennas will reduce the expense, weight, and RF loss of the antenna system. One way of producing a shaped contour beam without using a feed network is to use a single shaped reflector with a single feed element. For a prescribed contour beam and feed, an optimization method for designing the reflector shape is given. As a design example, a shaped reflector is designed to produce a continental U.S. coverage (CONUS) beam. The RF performance of the shaped reflector is then verified by physical optics.

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.

Study on Miniaturized UHF Antennas for Partial Discharge Detection in High-Voltage Electrical Equipment.

PubMed

Liu, Jingcun; Zhang, Guogang; Dong, Jinlong; Wang, Jianhua

2015-11-20

Detecting partial discharge (PD) is an effective way to evaluate the condition of high-voltage electrical equipment insulation. The UHF detection method has attracted attention due to its high sensitivity, strong interference resistance, and ability to locate PDs. In this paper, a miniaturized equiangular spiral antenna (ESA) for UHF detection that uses a printed circuit board is proposed. I-shaped, L-shaped, and C-shaped microstrip baluns were designed to match the impedance between the ESA and coaxial cable and were verified by a vector network analyzer. For comparison, three other types of UHF antenna were also designed: A microstrip patch antenna, a microstrip slot antenna, and a printed dipole antenna. Their antenna factors were calibrated in a uniform electric field of different frequencies modulated in a gigahertz transverse electromagnetic cell. We performed comparison experiments on PD signal detection using an artificial defect model based on the international IEC 60270 standard. We also conducted time-delay test experiments on the ESA sensor to locate a PD source. It was found that the proposed ESA sensor meets PD signal detection requirements. The sensor's compact size makes it suitable for internal installation in high-voltage electrical equipment.

Study on Miniaturized UHF Antennas for Partial Discharge Detection in High-Voltage Electrical Equipment

PubMed Central

Liu, Jingcun; Zhang, Guogang; Dong, Jinlong; Wang, Jianhua

2015-01-01

Detecting partial discharge (PD) is an effective way to evaluate the condition of high-voltage electrical equipment insulation. The UHF detection method has attracted attention due to its high sensitivity, strong interference resistance, and ability to locate PDs. In this paper, a miniaturized equiangular spiral antenna (ESA) for UHF detection that uses a printed circuit board is proposed. I-shaped, L-shaped, and C-shaped microstrip baluns were designed to match the impedance between the ESA and coaxial cable and were verified by a vector network analyzer. For comparison, three other types of UHF antenna were also designed: A microstrip patch antenna, a microstrip slot antenna, and a printed dipole antenna. Their antenna factors were calibrated in a uniform electric field of different frequencies modulated in a gigahertz transverse electromagnetic cell. We performed comparison experiments on PD signal detection using an artificial defect model based on the international IEC 60270 standard. We also conducted time-delay test experiments on the ESA sensor to locate a PD source. It was found that the proposed ESA sensor meets PD signal detection requirements. The sensor’s compact size makes it suitable for internal installation in high-voltage electrical equipment. PMID:26610506

EM Modeling of Far-Field Radiation Patterns for Antennas on the GMA-TT UAV

NASA Technical Reports Server (NTRS)

Mackenzie, Anne I.

2015-01-01

To optimize communication with the Generic Modular Aircraft T-Tail (GMA-TT) unmanned aerial vehicle (UAV), electromagnetic (EM) simulations have been performed to predict the performance of two antenna types on the aircraft. Simulated far-field radiation patterns tell the amount of power radiated by the antennas and the aircraft together, taking into account blockage by the aircraft as well as radiation by conducting and dielectric portions of the aircraft. With a knowledge of the polarization and distance of the two communicating antennas, e.g. one on the UAV and one on the ground, and the transmitted signal strength, a calculation may be performed to find the strength of the signal travelling from one antenna to the other and to check that the transmitted signal meets the receiver system requirements for the designated range. In order to do this, the antenna frequency and polarization must be known for each antenna, in addition to its design and location. The permittivity, permeability, and geometry of the UAV components must also be known. The full-wave method of moments solution produces the appropriate dBi radiation pattern in which the received signal strength is calculated relative to that of an isotropic radiator.

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.

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.

47 CFR 17.9 - Designated antenna farm areas.

Code of Federal Regulations, 2011 CFR

2011-10-01

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

47 CFR 17.9 - Designated antenna farm areas.

Code of Federal Regulations, 2010 CFR

2010-10-01

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

47 CFR 17.9 - Designated antenna farm areas.

Code of Federal Regulations, 2013 CFR

2013-10-01

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

47 CFR 17.9 - Designated antenna farm areas.

Code of Federal Regulations, 2012 CFR

2012-10-01

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

47 CFR 17.9 - Designated antenna farm areas.

Code of Federal Regulations, 2014 CFR

2014-10-01

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

Microstrip Yagi array for MSAT vehicle antenna application

NASA Technical Reports Server (NTRS)

Huang, John; Densmore, Arthur; Pozar, David

1990-01-01

A microstrip Yagi array was developed for the MSAT system as a low-cost mechanically steered medium-gain vehicle antenna. Because its parasitic reflector and director patches are not connected to any of the RF power distributing circuit, while still contributing to achieve the MSAT required directional beam, the antenna becomes a very efficient radiating system. With the complete monopulse beamforming circuit etched on a thin stripline board, the planar microstrip Yagi array is capable of achieving a very low profile. A theoretical model using the Method of Moments was developed to facilitate the ease of design and understanding of this antenna.

Computer-automated evolution of an X-band antenna for NASA's Space Technology 5 mission.

PubMed

Hornby, Gregory S; Lohn, Jason D; Linden, Derek S

2011-01-01

Whereas the current practice of designing antennas by hand is severely limited because it is both time and labor intensive and requires a significant amount of domain knowledge, evolutionary algorithms can be used to search the design space and automatically find novel antenna designs that are more effective than would otherwise be developed. Here we present our work in using evolutionary algorithms to automatically design an X-band antenna for NASA's Space Technology 5 (ST5) spacecraft. Two evolutionary algorithms were used: the first uses a vector of real-valued parameters and the second uses a tree-structured generative representation for constructing the antenna. The highest-performance antennas from both algorithms were fabricated and tested and both outperformed a hand-designed antenna produced by the antenna contractor for the mission. Subsequent changes to the spacecraft orbit resulted in a change in requirements for the spacecraft antenna. By adjusting our fitness function we were able to rapidly evolve a new set of antennas for this mission in less than a month. One of these new antenna designs was built, tested, and approved for deployment on the three ST5 spacecraft, which were successfully launched into space on March 22, 2006. This evolved antenna design is the first computer-evolved antenna to be deployed for any application and is the first computer-evolved hardware in space.

Application of the LQG/LTR technique to robust controller synthesis for a large flexible space antenna

NASA Technical Reports Server (NTRS)

Joshi, S. M.; Armstrong, E. S.; Sundararajan, N.

1986-01-01

The problem of synthesizing a robust controller is considered for a large, flexible space-based antenna by using the linear-quadratic-Gaussian (LQG)/loop transfer recovery (LTR) method. The study is based on a finite-element model of the 122-m hoop/column antenna, which consists of three rigid-body rotational modes and the first 10 elastic modes. A robust compensator design for achieving the required performance bandwidth in the presence of modeling uncertainties is obtained using the LQG/LTR method for loop-shaping in the frequency domain. Different sensor actuator locations are analyzed in terms of the pole/zero locations of the multivariable systems and possible best locations are indicated. The computations are performed by using the LQG design package ORACLS augmented with frequency domain singular value analysis software.

Convergence of the Quasi-static Antenna Design Algorithm

DTIC Science & Technology

2013-04-01

was the first antenna design with quasi-static methods. In electrostatics, a perfect conductor is the same as an equipotential surface . A line of...which can cause the equipotential surface to terminate on the disk or feed wire. This requires an additional step in the solution process; the... equipotential surface is sampled to verify that the charge is enclosed by the equipotential surface . The final solution must be verified with a detailed

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 operation in two frequency bands along with an additional port for CA in the third band. The four designs have been experimentally verified, validating the use of TCM as a versatile tool to design multi-functional chassis-based antennas.

Minimizing yagi-uda radiosonde receiver antenna size using minkowski curve fractal model

NASA Astrophysics Data System (ADS)

Sani, Arman; Suherman

2018-03-01

This paper discusses Yagi-Uda antenna design for radiosonde earth station receiver. The design was performed by using Minkowski curve fractal model to reduce physical dimension. The antenna design should fulfil the following requirements: work on frequency of 433MHz, match to the 50 Ohm of radiosonde characteristic impedance, the expected gain is higher than 10 dBi, VSWR is smaller than 2 and the expected bandwidth is higher than 10 MHz. Antenna design and evaluation were conducted by using MMANA-GAL simulator. The evaluation of the designed antenna shows that the Yagi-Uda antenna designed by using Minkowski curve model successfully reduces antenna size up to 9.41% and reduces number of elements about 33%.

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

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

Design of UWB Monopole Antenna with Dual Notched Bands Using One Modified Electromagnetic-Bandgap Structure

PubMed Central

Xu, Ziqiang

2013-01-01

A modified electromagnetic-bandgap (M-EBG) structure and its application to planar monopole ultra-wideband (UWB) antenna are presented. The proposed M-EBG which comprises two strip patch and an edge-located via can perform dual notched bands. By properly designing and placing strip patch near the feedline, the proposed M-EBG not only possesses a simple structure and compact size but also exhibits good band rejection. Moreover, it is easy to tune the dual notched bands by altering the dimensions of the M-EBG. A demonstration antenna with dual band-notched characteristics is designed and fabricated to validate the proposed method. The results show that the proposed antenna can satisfy the requirements of VSWR < 2 over UWB 3.1–10.6 GHz, except for the rejected bands of the world interoperability for microwave access (WiMAX) and the wireless local area network (WLAN) at 3.5 GHz and 5.5 GHz, respectively. PMID:24170984

UHF Antenna Design for AFIT Random Noise Radar

DTIC Science & Technology

2012-03-01

relatives of monopole , dipole, and slot antennas. One particularly interesting style amongst these is the Vivaldi antenna. There are two primary... monopole versions using Earth’s surface as a ground plane [26]. Antenna design and construction caught up with these early innovations over the next...Frequency independent antennas  Electric antennas (e.g. dipoles and monopoles )  Magnetic antennas (e.g. loops)  Electrically small antennas

Design of 5.8 GHz Integrated Antenna on 180nm Complementary Metal Oxide Semiconductor (CMOS) Technology

NASA Astrophysics Data System (ADS)

Razak, A. H. A.; Shamsuddin, M. I. A.; Idros, M. F. M.; Halim, A. K.; Ahmad, A.; Junid, S. A. M. Al

2018-03-01

This project discusses the design and simulation performances of integrated loop antenna. Antenna is one of the main parts in any wireless radio frequency integrated circuit (RFIC). Naturally, antenna is the bulk in any RFIC design. Thus, this project aims to implement an integrated antenna on a single chip making the end product more compact. This project targets 5.8 GHz as the operating frequency of the integrated antenna for a transceiver module based on Silterra CMOS 180nm technology. The simulation of the antenna was done by using High Frequency Structure Simulator (HFSS). This software is industrial standard software that been used to simulate all electromagnetic effect including antenna simulation. This software has ability to simulate frequency at range of 100 MHz to 4 THz. The simulation set up in 3 dimension structure with driven terminal. The designed antenna has 1400um of diameter and placed on top metal layer. Loop configuration of the antenna has been chosen as the antenna design. From the configuration, it is able to make the chip more compact. The simulation shows that the antenna has single frequency band at center frequency 5.8 GHz with -48.93dB. The antenna radiation patterns shows, the antenna radiate at omnidirectional. From the simulation result, it could be concluded that the antenna have a good radiation pattern and propagation for wireless communication.

Seventy-meter antenna performance predictions: GTD analysis compared with traditional ray-tracing methods

NASA Technical Reports Server (NTRS)

Schredder, J. M.

1988-01-01

A comparative analysis was performed, using both the Geometrical Theory of Diffraction (GTD) and traditional pathlength error analysis techniques, for predicting RF antenna gain performance and pointing corrections. The NASA/JPL 70 meter antenna with its shaped surface was analyzed for gravity loading over the range of elevation angles. Also analyzed were the effects of lateral and axial displacements of the subreflector. Significant differences were noted between the predictions of the two methods, in the effect of subreflector displacements, and in the optimal subreflector positions to focus a gravity-deformed main reflector. The results are of relevance to future design procedure.

Analysis and characterization of structurally embedded vascular antennas using liquid metals

NASA Astrophysics Data System (ADS)

Hartl, Darren J.; Huff, Gregory H.; Pan, Hong; Smith, Lisa; Bradford, Robyn L.; Frank, Geoffrey J.; Baur, Jeffrey W.

2016-04-01

Over the past decade, a large body of research associated with the addition of microvascular networks to structural composites has been generated. The engineering goal is most often the extension of structural utility to include extended functionalities such as self-healing or improved thermal management and resilience. More recently, efforts to design reconfigurable embedded electronics via the incorporation of non-toxic liquid metals have been initiated. A wide range of planar antenna configurations are possible, and the trade-offs between structural effects, other system costs, and increased flexibility in transmitting and receiving frequencies are being explored via the structurally embedded vascular antenna (SEVA) concept. This work describes for the first time the design of a bowtie-like tunable liquid metal-based antenna for integration into a structural composite for electromagnetic use. The design of both the solid/fluid feed structure and fluid transmission lines are described and analysis results regarding the RF performance of the antenna are provided. Fabrication methods for the SEVA are explained in detail and as-fabricated components are described. Challenges associated with both fabrication and system implementation and testing are elucidated. Results from preliminary RF testing indicate that in situ response tuning is feasible in these novel multifunctional composites.

Dual-slot antennas for microwave tissue heating: Parametric design analysis and experimental validation

PubMed Central

Brace, Christopher L.

2011-01-01

Purpose: Design and validate an efficient dual-slot coaxial microwave ablation antenna that produces an approximately spherical heating pattern to match the shape of most abdominal and pulmonary tumor targets.Methods: A dual-slot antenna geometry was utilized for this study. Permutations of the antenna geometry using proximal and distal slot widths from 1 to 10 mm separated by 1–20 mm were analyzed using finite-element electromagnetic simulations. From this series, the most optimal antenna geometry was selected using a two-term sigmoidal objective function to minimize antenna reflection coefficient and maximize the diameter-to-length aspect ratio of heat generation. Sensitivities to variations in tissue properties and insertion depth were also evaluated in numerical models. The most optimal dual-slot geometry of the parametric analysis was then fabricated from semirigid coaxial cable. Antenna reflection coefficients at various insertion depths were recorded in ex vivo bovine livers and compared to numerical results. Ablation zones were then created by applying 50 W for 2–10 min in simulations and ex vivo livers. Mean zone diameter, length, aspect ratio, and reflection coefficients before and after heating were then compared to a conventional monopole antenna using ANOVA with post-hoc t-tests. Statistical significance was indicated for P < 0.05.Results: Antenna performance was highly sensitive to dual-slot geometry. The best-performing designs utilized a proximal slot width of 1 mm, distal slot width of 4 mm ± 1 mm and separation of 8 mm ± 1 mm. These designs were characterized by an active choking mechanism that focused heating to the distal tip of the antenna. A dual-band resonance was observed in the most optimal design, with a minimum reflection coefficient of −20.9 dB at 2.45 and 1.25 GHz. Total operating bandwidth was greater than 1 GHz, but the desired heating pattern was achieved only near 2.45 GHz. As a result, antenna performance was robust to changes in insertion depth and variations in relative permittivity of the surrounding tissue medium. In both simulations and ex vivo liver, the dual-slot antenna created ablations greater in diameter than a coaxial monopole (35 mm ± 2 mm versus 31 mm ± 2 mm; P < 0.05), while also shorter in length (49 mm ± 2 mm versus 60 mm ± 6 mm; P < 0.001) after 10 min. Similar results were obtained after 2 and 5 min as well.Conclusions: Dual-slot antennas can produce more spherical ablation zones while retaining low reflection coefficients. These benefits are obtained without adding to the antenna diameter. Further evaluation for clinical microwave ablation appears warranted. PMID:21859025

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.

Antenna coupled photonic wire lasers

DOE PAGES

Kao, Tsung-Kao; Cai, Xiaowei; Lee, Alan W. M.; ...

2015-06-22

Slope efficiency (SE) is an important performance metric for lasers. In conventional semiconductor lasers, SE can be optimized by careful designs of the facet (or the modulation for DFB lasers) dimension and surface. However, photonic wire lasers intrinsically suffer low SE due to their deep sub-wavelength emitting facets. Inspired by microwave engineering techniques, we show a novel method to extract power from wire lasers using monolithically integrated antennas. These integrated antennas significantly increase the effective radiation area, and consequently enhance the power extraction efficiency. When applied to wire lasers at THz frequency, we achieved the highest single-side slope efficiency (~450more » mW/A) in pulsed mode for DFB lasers at 4 THz and a ~4x increase in output power at 3 THz compared with a similar structure without antennas. This work demonstrates the versatility of incorporating microwave engineering techniques into laser designs, enabling significant performance enhancements.« less

Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

NASA Technical Reports Server (NTRS)

Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

2003-01-01

Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

Dual band new bisected-Π CRLH metamaterial cell loaded dipole antennas

NASA Astrophysics Data System (ADS)

Abdalla, M. A.; Ghouz, M. H.; Abo El-Dahab, M.

2018-06-01

In this paper, two different designs for new metamaterial loaded dipole antenna are presented. The designs are based on loading printed dipole antennas with modified versions of composite right left handed cells. Different objectives are intended for these new designs; which are achieving compact size, dual band functionalities and good gain of the loaded dipole antenna. The designed antennas can serve different wireless services for GPS (1.227 GHz and 1.57 GHz), Universal Telecommunications System (UMTS 1.9 GHz), and WiFi (2.4 GHz). The two presented antennas have gain whose values are better than 1.9 dB up to 3.5 dB at all operating frequencies. The designed loading has reduced the physical / electrical length of conventional dipole antenna by 25%. The theoretical analysis, circuit model, full wave simulations and experimental measurements of the reported antennas are introduced.

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.

Compact Miniaturized Antenna for 210 MHz RFID

NASA Technical Reports Server (NTRS)

Lee, Richard Q.; Chun, Kue

2008-01-01

This paper describes the design and simulation of a miniaturized square-ring antenna. The miniaturized antenna, with overall dimensions of approximately one tenth of a wavelength (0.1 ), was designed to operate at around 210 MHz, and was intended for radio-frequency identification (RFID) application. One unique feature of the design is the use of a parasitic element to improve the performance and impedance matching of the antenna. The use of parasitic elements to enhance the gain and bandwidth of patch antennas has been demonstrated and reported in the literature, but such use has never been applied to miniaturized antennas. In this work, we will present simulation results and discuss design parameters and their impact on the antenna performance.

Efficient RF energy harvesting by using a fractal structured rectenna system

NASA Astrophysics Data System (ADS)

Oh, Sechang; Ramasamy, Mouli; Varadan, Vijay K.

2014-04-01

A rectenna system delivers, collects, and converts RF energy into direct current to power the electronic devices or recharge batteries. It consists of an antenna for receiving RF power, an input filter for processing energy and impedance matching, a rectifier, an output filter, and a load resistor. However, the conventional rectenna systems have drawback in terms of power generation, as the single resonant frequency of an antenna can generate only low power compared to multiple resonant frequencies. A multi band rectenna system is an optimal solution to generate more power. This paper proposes the design of a novel rectenna system, which involves developing a multi band rectenna with a fractal structured antenna to facilitate an increase in energy harvesting from various sources like Wi-Fi, TV signals, mobile networks and other ambient sources, eliminating the limitation of a single band technique. The usage of fractal antennas effects certain prominent advantages in terms of size and multiple resonances. Even though, a fractal antenna incorporates multiple resonances, controlling the resonant frequencies is an important aspect to generate power from the various desired RF sources. Hence, this paper also describes the design parameters of the fractal antenna and the methods to control the multi band frequency.

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

PubMed

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

2014-01-01

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

Design and Fabrication of High Gain Multi-element Multi-segment Quarter-sector Cylindrical Dielectric Resonator Antenna

NASA Astrophysics Data System (ADS)

Ranjan, Pinku; Gangwar, Ravi Kumar

2017-12-01

A novel design and analysis of quarter cylindrical dielectric resonator antenna (q-CDRA) with multi-element and multi-segment (MEMS) approach has been presented. The MEMS q-CDRA has been designed by splitting four identical quarters from a solid cylinder and then multi-segmentation approach has been utilized to design q-CDRA. The proposed antenna has been designed for enhancement in bandwidth as well as for high gain. For bandwidth enhancement, multi-segmentation method has been explained for the selection of dielectric constant of materials. The performance of the proposed MEMS q-CDRA has been demonstrated with design guideline of MEMS approach. To validate the antenna performance, three segments q-CDRA has been fabricated and analyzed practically. The simulated results have been in good agreement with measured one. The MEMS q-CDRA has wide impedance bandwidth (|S11|≤-10 dB) of 133.8 % with monopole-like radiation pattern. The proposed MEMS q-CDRA has been operating at TM01δ mode with the measured gain of 6.65 dBi and minimum gain of 4.5 dBi in entire operating frequency band (5.1-13.7 GHz). The proposed MEMS q-CDRA may find appropriate applications in WiMAX and WLAN band.

High temperature antenna development for space shuttle, volume 1

NASA Technical Reports Server (NTRS)

Kuhlman, E. A.

1973-01-01

Design concepts for high temperature flush mounted Space Shuttle Orbiter antenna systems are discussed. The design concepts include antenna systems for VHF, L-band, S-band, C-band and Ku-band frequencies. The S-band antenna system design was completed and test hardware fabricated. It was then subjected to electrical and thermal testing to establish design requirements and determine reuse capabilities. The thermal tests consisted of applying ten high temperature cycles simulating the Orbiter entry heating environment in an arc tunnel plasma facility and observing the temperature distributions. Radiation pattern and impedance measurements before and after high temperature exposure were used to evaluated the antenna systems performance. Alternate window design concepts are considered. Layout drawings, supported by thermal and strength analyses, are given for each of the antenna system designs. The results of the electrical and thermal testing of the S-band antenna system are given.

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.

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

NASA Technical Reports Server (NTRS)

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

2007-01-01

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

Project Cyclops: a Design Study of a System for Detecting Extraterrestrial Intelligent Life

NASA Technical Reports Server (NTRS)

1972-01-01

The requirements in hardware, manpower, time and funding to conduct a realistic effort aimed at detecting the existence of extraterrestrial intelligent life are examined. The methods used are limited to present or near term future state-of-the-art techniques. Subjects discussed include: (1) possible methods of contact, (2) communication by electromagnetic waves, (3) antenna array and system facilities, (4) antenna elements, (5) signal processing, (6) search strategy, and (7) radio and radar astronomy.

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.

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.

A 915-MHz antenna for microwave thermal ablation treatment: physical design, computer modeling and experimental measurement.

PubMed

Pisa, S; Cavagnaro, M; Bernardi, P; Lin, J C

2001-05-01

A 915-MHz antenna design that produces specific absorption rate distributions with preferential power deposition in tissues surrounding and including the distal end of the catheter antenna is described. The design features minimal reflected microwave current from the antenna flowing up the transmission line. This cap-choke antenna consists of an annular cap and a coaxial choke which matches the antenna to the coaxial transmission line. The design minimizes heating of the coaxial cable and its performance is not affected by the depth of insertion of the antenna into tissue. The paper provides a comparison of results obtained from computer modeling and experimental measurements made in tissue equivalent phantom materials. There is excellent agreement between numerical modeling and experimental measurement. The cap-choke, matched-dipole type antenna is suitable for intracavitary microwave thermal ablation therapy.

Modern Design of Resonant Edge-Slot Array Antennas

NASA Technical Reports Server (NTRS)

Gosselin, R. B.

2006-01-01

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

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.

Rover Low Gain Antenna Qualification for Deep Space Thermal Environments

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni; Amaro, Luis R.; Brown, Paula R.; Usiskin, Robert; Prater, Jack L.

2013-01-01

A method to qualify the Rover Low Gain Antenna (RLGA) for use during the Mars Science Laboratory (MSL) mission has been devised. The RLGA antenna must survive all ground operations, plus the nominal 670 Martian sol mission that includes the summer and winter seasons of the Mars thermal environment. This qualification effort was performed to verify that the RLGA design, its bonding, and packaging processes are adequate. 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 on the RLGA hardware before the start of the qualification test. Functional intermittent RF tests were performed during thermal chamber breaks over the course of the complete qualification test. For the return loss measurements, the RLGA antenna was moved to a test area. A vector network analyzer was calibrated over the operational frequency range of the antenna. For the RLGA, a simple return loss measurement was performed. A total of 2,010 (3 670 or 3 times mission thermal cycles) thermal cycles was performed. Visual inspection of the RLGA hardware did not show any anomalies due to the thermal cycling. The return loss measurement results of the RLGA antenna after the PQV (Package Qualification and Verification) test did not show any anomalies. The antenna pattern data taken before and after the PQV test at the uplink and downlink frequencies were unchanged. Therefore, the developed design of RLGA is qualified for a long-duration MSL mission.

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.

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.

A novel neural network for the synthesis of antennas and microwave devices.

PubMed

Delgado, Heriberto Jose; Thursby, Michael H; Ham, Fredric M

2005-11-01

A novel artificial neural network (SYNTHESIS-ANN) is presented, which has been designed for computationally intensive problems and applied to the optimization of antennas and microwave devices. The antenna example presented is optimized with respect to voltage standing-wave ratio, bandwidth, and frequency of operation. A simple microstrip transmission line problem is used to further describe the ANN effectiveness, in which microstrip line width is optimized with respect to line impedance. The ANNs exploit a unique number representation of input and output data in conjunction with a more standard neural network architecture. An ANN consisting of a heteroassociative memory provided a very efficient method of computing necessary geometrical values for the antenna when used in conjunction with a new randomization process. The number representation used provides significant insight into this new method of fault-tolerant computing. Further work is needed to evaluate the potential of this new paradigm.

Far-Field to Near-Field Coupling for Enhancing Light-Matter Interaction

NASA Astrophysics Data System (ADS)

Bonakdar, Alireza

This thesis reports on theoretical, modeling, and experimental research within the framework of a key scientific question, which is enhancing the coupling between diffraction-limited far-field and sub-wavelength quantum emitter/absorber. A typical optoelectronic device delivers an optical process such as light detection (e.g. photodetector) or light intensity modulation (e.g. electro-absorptive modulator). In conventional devices, optical process is in the form of far-field or guided wave modes. The main aim of this thesis is to show that converting these modes into near-field domain can enhance the performance of the optoelectronic device. Light in the form of far-field can be converted into near-field domain by the optical antenna. Among different optoelectronic devices, this thesis focuses mainly on integrating the optical antenna with infrared photodetectors. The available semiconductors have weak infrared absorption that reduces light detection efficiency. Integration of the optical antenna with infrared absorber (such as quantum wells in quantum well infrared photodetector (QWIP)) increases the infrared absorption. Particularly this integration is favorable as the optical antenna has low metallic loss in infrared region. The author of this thesis believes that optical antenna has unique properties in confining light on the scale of deep sub-wavelength, enhancing electric field intensity and delivering optical energy to semiconductor absorbers. These properties are reaching into practical applications only if overall optical performance is low loss, parameter free (independent of optical parameters such a polarization and angle of incident) and broadband. In this thesis, the integration of optical antenna with infrared photodetectors and thermophotovoltaic are researched and developed which satisfy the aforementioned criteria. In addition, several different optical antennas have been designed, fabricated and characterized in order to analyze and demonstrate the improvement of infrared absorption. In terms of design, novel optical antennas were simulated and proposed for a variety of infrared photodetectors such as a quantum well infrared photodetector, metal-insulator-metal detector, Schottky infrared photodetector, and two-photon absorption infrared detector. Antenna analyzes are not limited to light detection as a chapter of this thesis devoted on design and develop of a low power and ultrafast all-optical/optomechanical switchable antenna. The rest of the manuscript contains the novel lithography method in order to fabricate optical antennas with low cost and in cm-scale area. The method is based on the microsphere photolithography that expose photoresist underneath each microsphere with a focused intensive light -so called photonic nanojet. The developed lithography method takes advantage of microscopic range of optical path (micro-optics) in microsphere lenses that allows to push the exposure wavelength beyond deep UV region, where the refractive optics becomes impractical due to severe material absorption. The author believes that micro-optics lithography is an excellent candidate for large area and high throughput fabrication of sub-100-nm feature sizes in periodic array. In particular, this method facilitates the feasibility of metasurfaces and metamaterials, optical coating with efficient photon extraction/trapping, and highly sensitive bio-sensors in near IR and visible ranges of spectrum.

Microstrip patch antenna for simultaneous strain and temperature sensing

NASA Astrophysics Data System (ADS)

Mbanya Tchafa, F.; Huang, H.

2018-06-01

A patch antenna, consisting of a radiation patch, a dielectric substrate, and a ground plane, resonates at distinct fundamental frequencies that depend on the substrate dielectric constant and the dimensions of the radiation patch. Since these parameters change with the applied strain and temperature, this study investigates simultaneous strain and temperature sensing using a single antenna that has two fundamental resonant frequencies. The theoretical relationship between the antenna resonant frequency shifts, the temperature, and the applied strain was first established to guide the selection of the dielectric substrate, based on which an antenna sensor with a rectangular radiation patch was designed and fabricated. A tensile test specimen instrumented with the antenna sensor was subjected to thermo-mechanical tests. Experiment results validated the theoretical predictions that the normalized antenna resonant frequency shifts are linearly proportional to the applied strain and temperature changes. An inverse method was developed to determine the strain and temperature changes from the normalized antenna resonant frequency shifts, yielding measurement uncertainty of 0.4 °C and 17.22 μ \\varepsilon for temperature and strain measurement, respectively.

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.

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.

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.

Large space antenna communications systems: Integrated Langley Research Center/Jet Propulsion Laboratory technology development activities. 1: Introduction

NASA Technical Reports Server (NTRS)

Campbell, T. G.

1983-01-01

The Jet Propulsion Laboratory and the Langley Research Center have been developing technology related to large space antennas (LSA) during the past several years. The need for a communication system research program became apparent during the recent studies for the Land Mobile Satellite System. This study indicated the need for additional research in (1) electromagnetic analysis methods, (2) design and development of multiple beam feed systems, and (3) the measurement methods for LSA reflectors.

[Activities of the Department of Electrical Engineering, Howard University

NASA Technical Reports Server (NTRS)

Yalamanchili, Raj C.

1997-01-01

Theoretical derivations, computer analysis and test data are provided to demonstrate that the cavity model is a feasible one to analyze thin-substrate, rectangular-patch microstrip antennas. Seven separate antennas were tested. Most of the antennas were designed to resonate at L-band frequencies (1-2 GHz). One antenna was designed to resonate at an S-band (2-4 GHz) frequency of 2.025 GHz. All dielectric substrates were made of Duroid, and were of varying thicknesses and relative dielectric constant values. Theoretical derivations to calculate radiated free space electromagnetic fields and antenna input impedance were performed. MATHEMATICA 2.2 software was used to generate Smith Chart input impedance plots, normalized relative power radiation plots and to perform other numerical manipulations. Network Analyzer tests were used to verify the data from the computer programming (such as input impedance and VSWR). Finally, tests were performed in an anechoic chamber to measure receive-mode polar power patterns in the E and H planes. Agreement between computer analysis and test data is presented. The antenna with the thickest substrate (e(sub r) = 2.33,62 mils thick) showed the worst match to theoretical impedance data. This is anticipated due to the fact that the cavity model generally loses accuracy when the dielectric substrate thickness exceeds 5% of the antenna's free space wavelength. A method of reducing computer execution time for impedance calculations is also presented.

Advanced Antenna Design for NASA's EcoSAR Instrument

NASA Technical Reports Server (NTRS)

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

2016-01-01

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

The Use of Conductive Ink in Antenna Education and Design

ERIC Educational Resources Information Center

Addison, David W.

2017-01-01

Conductive ink from a printer allows for the fabrication of conductive material with tight tolerances without the cost and time of chemical etching. This paper explores the use of AGIC printable conductive ink on a paper substrate as design tool for antennas as well as classroom use in antenna education. The antenna designs satisfy the…

Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio-Inspired Optimization Techniques

DTIC Science & Technology

2017-11-01

ARL-TR-8225 ● NOV 2017 US Army Research Laboratory Methodology for Designing and Developing a New Ultra-Wideband Antenna Based...Research Laboratory Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio-Inspired Optimization Techniques by...SUBTITLE Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio-Inspired Optimization Techniques 5a. CONTRACT NUMBER

Quasi-static Design of Electrically Small Ultra-Wideband Antennas

DTIC Science & Technology

2017-02-01

this design reduces the width of the antenna, which implies that the bulb shape can be non -spherical at high frequencies. The stored energy in an...conclusion. The Quasi-static Antenna Design Algorithm generates three UWB non -spherical bulb shapes. The non -spherical bulb shape performs as well...TECHNICAL REPORT 3056 February 2017 Quasi-static Design of Electrically Small Ultra-Wideband Antennas Thomas O. Jones III Approved for public

The Use of Conductive Ink in Antenna Education and Design

NASA Astrophysics Data System (ADS)

Addison, David W.

Conductive ink from a printer allows for the fabrication of conductive material with tight tolerances without the cost and time of chemical etching. This paper explores the use of AGIC printable conductive ink on a paper substrate as design tool for antennas as well as classroom use in antenna education. The antenna designs satisfy the requirements of a compact Global Navigation Satellite System (GNSS) antenna while showing a competitive performance within the current market. One best design is shown along with three other structures. These antennas consist of a bowtie cross-dipole over a reflective disc with conductive-ink grounded structures. In addition to the GNSS antennas, a linear elliptical dipole over a reflective disc with conductive grounded structures is presented. This elliptical antenna design attempts to find the maximum impedance bandwidth beyond the GNSS band. The inexpensive nature of conductive ink allows for its use in a classroom to demonstrate antenna behavior as part of antenna education. An inexpensive approach to the patch antenna using conductive ink is described and paired with a system made of off-the-shelf parts. The system is capable of measuring the power of the received signal. The received signal measurement is not as accurate as using a anechoic chamber but pattern details are visible. This is used to demonstrate aspects of the Friis transmission equation such as distance, polarization, radiation pattern shape, and loss.

Hybrid method to predict the resonant frequencies and to characterise dual band proximity coupled microstrip antennas

NASA Astrophysics Data System (ADS)

Varma, Ruchi; Ghosh, Jayanta

2018-06-01

A new hybrid technique, which is a combination of neural network (NN) and support vector machine, is proposed for designing of different slotted dual band proximity coupled microstrip antennas. Slots on the patch are employed to produce the second resonance along with size reduction. The proposed hybrid model provides flexibility to design the dual band antennas in the frequency range from 1 to 6 GHz. This includes DCS (1.71-1.88 GHz), PCS (1.88-1.99 GHz), UMTS (1.92-2.17 GHz), LTE2300 (2.3-2.4 GHz), Bluetooth (2.4-2.485 GHz), WiMAX (3.3-3.7 GHz), and WLAN (5.15-5.35 GHz, 5.725-5.825 GHz) bands applications. Also, the comparative study of this proposed technique is done with the existing methods like knowledge based NN and support vector machine. The proposed method is found to be more accurate in terms of % error and root mean square % error and the results are in good accord with the measured values.

Design and analysis microstrip dipole using fractal Koch for 433 MHz applications

NASA Astrophysics Data System (ADS)

Zulfin, M.; Rambe, A. H.; Budi, B.

2018-02-01

This paper discussed the dipole microstrip antenna design using fractal Koch for working on frequency of 433 MHz. The fractal Koch was used to reduce the size of the microstrip antenna. The smaller the antenna size, the lighter the equipment. AWR simulator was employed to evaluate antenna parameters such as return loss, gain and radiation pattern. The antenna was designed on a FR4 substrate with relative permittivity of 4.4 and thickness 1.6 mm. The result shows that the fractal Koch reduce antenna size about 41.2% and decrease return loss about 30%.

A miniaturized micro strip antenna based on sinusoidal patch geometry for implantable biomedical applications

NASA Astrophysics Data System (ADS)

Ibrahim, Omar A.; Elwi, Taha A.; Islam, Naz E.

2012-11-01

A miniaturized microstrip antenna is analyzed for implantable biomedical applications. The antenna is designed using two different commercial software packages, CST Microwave Studio and HFSS, to validate the results. The proposed design operates in the WMTS frequency band. The antenna performance is tested inside the human body, Hugo model. The antenna design is readjusted to get the desired resonant frequency. The resonant frequency, bandwidth, gain, and radiation pattern of the proposed antenna are provided in this paper. Furthermore, the effect of losses inside human body due to the fat layer is recognized.

Conformal Lightweight Antenna Structures for Aeronautical Communication Technologies

NASA Technical Reports Server (NTRS)

Meador, Mary Ann

2017-01-01

This project is to develop antennas which enable beyond line of sight (BLOS) command and control for UAVs. We will take advantage of newly assigned provisional Ku-band spectrum for UAVs and use unique antenna designs to avoid interference with ground systems. This will involve designing antennas with high isotropic effective radiated power (EIRP) and ultra-low sidelobes. The antennas will be made with polymer aerogel as a substrate to both reduce weight and improve performance, as demonstrated in an Aero Seedling. In addition, designing the antennas to be conformal to the aircraft fuselage will reduce drag.

Design and Fabrication of Graphene Reinforced Polymer Conductive Patch-Based Inset Fed Microstrip Antenna

NASA Astrophysics Data System (ADS)

Deepak, A.; Kannan, P. Muthu; Shankar, P.

This work explores the design and fabrication of graphene reinforced polyvinylidene fluoride (PVDF) patch-based microstrip antenna. Primarily, antenna was designed at 6GHz frequency and simulation results were obtained using Ansoft HFSS tool. Later fabrication of antenna was carried out with graphene-PVDF films as conducting patch deposited on bakelite substrate and copper as ground plane. Graphene-PVDF films were prepared using solvent casting process. The radiation efficiency of fabricated microstrip patch antenna was 48% entailing it to be adapted as a practically functional antenna. Both simulated and the practical results were compared and analyzed.

Phase-tuning Metasurface for Circularly Polarized Broadside Radiation in Broadband.

PubMed

Zhang, Youfei; Wang, Haogang; Liao, Dashuang; Fu, Weijie

2018-02-14

Metasurface antennas (MAs) have been proposed as innovative alternatives to conventional bulky configurations for satellite applications because of their low profile, low cost, and high gain. The general method of surface impedance modulation for designing MAs is complicated, and achieving broad operation bandwidth remains a challenge because of its high dispersion response. We propose a novel and easy technique to control cylindrical surface waves radiated by a phase-tuning metasurface. Simultaneously, this technique exhibits a considerably wide working bandwidth. A detailed analysis of the radiation mechanism is discussed. A left-hand circularly polarized (LHCP) antenna and a right-hand circularly polarized (RHCP) antenna that are based on the phase-tuning metasurface are simulated and measured. The measured fractional 3-dB gain bandwidth and gain are higher than 17% and 15.57 dBi, respectively, which are consistent with the simulated results. Moreover, 30% 3-dB axial ratio is achieved for the LHCP and RHCP antennas. To the best knowledge of the authors, it is for the first time to realize a circularly polarized broadband MA by using the phase-tuning mechanism. The approach can be regarded as a new starting point for antenna design, thereby paving the way for the development of broadband and low-profile antennas for future satellite communication.

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

PubMed Central

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

2014-01-01

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

A Low Loss Microstrip Antenna for Radiometric Applications

NASA Technical Reports Server (NTRS)

Wahid, Parveen

2000-01-01

The design and analysis of a series-fed, low-loss, inverted microstrip array antenna, operating at 1.413 GHz is presented. The antenna is composed of two subarrays. Each subarray consists of an equal number of microstrip patches all connected together with microstrip lines. In the first design microstrip array for linear polarization is presented which incorporated a series feeding technique. The next design, which is capable of dual linear polarization (V-polarization and H-polarization), utilizes a corporate feed network for the V-pol and series feed arrangement for the H-pol. The first element of each subarray for H-pol is coaxially fed with a 180 deg phase difference. This approach ensures a symmetric radiation pattern on broadside in H-pol. For the V-pol two feeds are in the same phase on the two subarrays ensuring a broadside beam in V-pol. The designs presented here are simulated using the IE3D code that utilizes the method of moments. Measured results are compared with simulated results and show good agreement.

Conformal array design on arbitrary polygon surface with transformation optics

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

Deng, Li, E-mail: dengl@bupt.edu.cn; Hong, Weijun, E-mail: hongwj@bupt.edu.cn; Zhu, Jianfeng

2016-06-15

A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.

Diagnostic techniques for measurement of aerodynamic noise in free field and reverberant environment of wind tunnels

NASA Technical Reports Server (NTRS)

El-Sum, H. M. A.; Mawardi, O. K.

1973-01-01

Techniques for studying aerodynamic noise generating mechanisms without disturbing the flow in a free field, and in the reverberation environment of the ARC wind tunnel were investigated along with the design and testing of an acoustic antenna with an electronic steering control. The acoustic characteristics of turbojet as a noise source, detection of direct sound from a source in a reverberant background, optical diagnostic methods, and the design characteristics of a high directivity acoustic antenna. Recommendations for further studies are included.

Integrated Solar-Panel Antenna Array for CubeSats

NASA Technical Reports Server (NTRS)

Baktur, Reyhan

2016-01-01

The goal of the Integrated Solar-Panel Antenna Array for CubeSats (ISAAC) project is to design and demonstrate an effective and efficien toptically transparent, high-gain, lightweight, conformal X-band antenna array that is integrated with the solar panels of a CubeSat. The targeted demonstration is for a Near Earth Network (NEN)radio at X-band, but the design can be easilyscaled to other network radios for higher frequencies. ISAAC is a less expensive and more flexible design for communication systemscompared to a deployed dish antenna or the existing integrated solar panel antenna design.

Design of Balanced Mixers for ALMA Band-10

NASA Astrophysics Data System (ADS)

Shitov, Sergey V.; Koryukin, Oleg V.; Uzawa, Yoshinori; Noguchi, Takashi; Uvarov, Andrey V.; Bukovski, Maksim A.; Cohn, Ilya A.

2007-06-01

Two variants of balanced mixer employing twin-SIS structure are under development for 787-950 GHz frequency range. Easy-to-use Geometry Transformation method for modeling of superconducting microstrips is developed, compared to referenced methods and used for design of the mixers. Lens-antenna mixer is based on cross-slot antenna; it does not need any intervening optics between its lens and sub-reflector of ALMA telescope; simple yet efficient composition of lens-antenna cartridge is suggested. Compact single-chamber balanced waveguide mixer employs two SIS chips and capacitive probe for LO injection; coupling above -3 dB and signal loss below -20 dB are expected. Need in shifting of resonance frequency of twin-SIS mixer towards top of the frequency band is predicted using Tucker's theory in large-signal approximation. TRX considerably below 200 K (DSB) is simulated using high-quality hybrid SIS junction for NbTiN/Nb - AlOx - Nb/Al for Jc = 12 kA/cm2.

Highly Directive Reflect Array Antenna Design for Wireless Power Transfer

DTIC Science & Technology

2017-04-14

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

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

Kung, C C; Brunkhorst, C; Greenough, N

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

Mutual Elements and Substrate Effect Analysis on Patch Antenna Arrays

NASA Astrophysics Data System (ADS)

Wallace, Matthew J.

There have been many different technology advancements with the invention of solid state electronics, leading to the digital era which has changed the way users employ electronic circuits. Antennas are no different; however, they are still analog devices. With the advancements in technology, antennas are being fabricated on much higher frequencies and with greater bandwidths, all while trying to keep size and weight to a minimum. Centimeter and millimeter wave technologies have evolved for many different radio frequency (RF) applications. Microstrip patch antennas have been developed, as wire and tubular antenna elements are difficult to fabricate with the tolerances required at micro-wavelengths. Microstrip patch antennas are continuously being improved. These types of antennas are great for embedded or conformal applications where size and weight are of the essence and the ease of manufacturing elements to tight tolerances is important. One of the greatest benefits of patch antennas is the ease in creating an array. Many simulation programs have been created to assist in the design of patch antennas and arrays. However, there are still discrepancies between simulated results and actual measurements. This research will focus on these differences. It begins with a literature research of patch antenna design, followed by an assessment of simulation programs used for patch antenna design. The resulting antenna design was realized by the fabrication of an antenna from the Genesys software. Laboratory measurements of the real-world antenna are then compared to the theoretical antenna characteristics. This process is used to illustrate deficiencies in the software models and likely improvements that need to be made.

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.

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.

Microwave Treatment for Cardiac Arrhythmias

NASA Technical Reports Server (NTRS)

Hernandez-Moya, Sonia

2009-01-01

NASA seeks to transfer the NASA developed microwave ablation technology, designed for the treatment of ventricular tachycardia (irregular heart beat), to industry. After a heart attack, many cells surrounding the resulting scar continue to live but are abnormal electrically; they may conduct impulses unusually slowly or fire when they would typically be silent. These diseased areas might disturb smooth signaling by forming a reentrant circuit in the muscle. The objective of microwave ablation is to heat and kill these diseased cells to restore appropriate electrical activity in the heart. This technology is a method and apparatus that provides for propagating microwave energy into heart tissues to produce a desired temperature profile therein at tissue depths sufficient for thermally ablating arrhythmogenic cardiac tissue while preventing excessive heating of surrounding tissues, organs, and blood. A wide bandwidth double-disk antenna is effective for this purpose over a bandwidth of about six gigahertz. A computer simulation provides initial screening capabilities for an antenna such as antenna, frequency, power level, and power application duration. The simulation also allows optimization of techniques for specific patients or conditions. In comparison with other methods that involve direct-current pulses or radio frequencies below 1 GHz, this method may prove more effective in treating ventricular tachycardia. This is because the present method provides for greater control of the location, cross-sectional area, and depth of a lesion via selection of the location and design of the antenna and the choice of microwave power and frequency.

Design and development of a unit element microstrip antenna for aircraft collision avoidance system

NASA Astrophysics Data System (ADS)

De, Debajit; Sahu, Prasanna Kumar

2017-10-01

Aircraft/traffic alert and collision avoidance system (ACAS/TCAS) is an airborne system which is designed to provide the service as a last defense equipment for avoiding mid-air collisions between the aircraft. In the existing system, four monopole stub-elements are used as ACAS directional antenna and one blade type element is used as ACAS omnidirectional antenna. The existing ACAS antenna has some drawbacks such as low gain, large beamwidth, frequency and beam tuning/scanning issues etc. Antenna issues like unwanted signals reception may create difficulties to identify the possible threats. In this paper, the focus is on the design and development of a unit element microstrip antenna which can be used for ACAS application and to overcome the possible limitations associated with the existing techniques. Two proposed antenna models are presented here, which are single feed and dual feed microstrip dual patch slotted antenna. These are designed and simulated in CST Microwave Studio tool. The performance and other antenna characteristics have been explored from the simulation results followed by the antenna fabrication and measurement. A good reflection coefficient, Voltage Standing Wave Ratio (VSWR), narrow beamwidth, perfect directional radiation pattern, high gain and directivity make this proposed antenna a good candidate for this application.

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

PubMed

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

2008-12-01

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

Vehicle antenna development for mobile satellite applications

NASA Technical Reports Server (NTRS)

Woo, K.

1988-01-01

The paper summarizes results of a vehicle antenna program at JPL in support of a developing U.S. mobile satellite services (MSS) designed to provide telephone and data services for the continental United States. Two classes of circularly polarized vehicle antennas have been considered for the MSS: medium-gain, satellite-tracking antennas with 10-12-dBic gain; and low-gain, azimuthally omnidirectional antennas with 3-5-dBic gain. The design and performance of these antennas are described, and the two antennas are shown to have peculiar advantages and disadvantages.

Design and analysis of coplanar waveguide triple-band antenna based on defected ground structure

NASA Astrophysics Data System (ADS)

Lv, Hong; Chen, Wanli; Xia, Xinsheng; Qi, Peng; Sun, Quanling

2017-11-01

A kind of coplanar waveguide triple-band antenna based on defected ground structure is proposed, which has novel structure. Three batches with different frequency band are constructed by utilizing line combination, overlapping, and symmetry method. Stop band signals among three frequency bands are effectively suppressed by slots with different structures. More satisfactory impedance matching is realized by means of changing slot structure and improving return-loss. The presented antenna can operates simultaneously in various systems such as 3G / 4G wireless communication, Bluetooth, Worldwide Interoperability for Microwave Access, Wireless LAN. Test results show that the antenna has good radiation and gain in its working frequency band, and that it has great application potentials.

Some problems of the design of highly directional spacecraft antennas

NASA Technical Reports Server (NTRS)

Prigoda, B. A.

1974-01-01

Problems of optimization and selection of the most expedient forms of design of directional antenna systems encountered in spacecraft design are discussed. Selection of a given type of antenna depends on its characteristic size, weight, and potential.

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

NASA Technical Reports Server (NTRS)

Imbriale, William A.

2005-01-01

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

GPR application of the conical spiral antenna probe

NASA Astrophysics Data System (ADS)

Raemer, Harold R.; Rappaport, Carey M.

2001-10-01

The project motivating this paper is the deployment of a frequency independent antenna on the transceiver of a monostatic ground-penetrating radar used to detect mines. The design goal is that the radiation pattern and input impedance to nearly uniform over a band from 1 GHz to 5GHz if the antenna is partially immersed in a typical soil medium. The contemplated method of deployment is to have the antenna straddle the air-soil interface i.e. partly in free space and partly underground, radiating into the ground. The particular subclass of frequency-independent antenna under investigation for this application is the conical equiangular-spiral antenna, in which thin wires are wound around a conical frame and the radiation is from the apex and reaches its peak in the axial direction. The conical structure, about 50cm long and with a maximum diameter of 12cm, is thrust into the ground apex-first at an angle of about 70 degrees to the vertical.

Antenna-load interactions at optical frequencies: impedance matching to quantum systems.

PubMed

Olmon, R L; Raschke, M B

2012-11-09

The goal of antenna design at optical frequencies is to deliver optical electromagnetic energy to loads in the form of, e.g., atoms, molecules or nanostructures, or to enhance the radiative emission from such structures, or both. A true optical antenna would, on a qualitatively new level, control the light-matter interaction on the nanoscale for controlled optical signal transduction, radiative decay engineering, quantum coherent control, and super-resolution microscopy, and provide unprecedented sensitivity in spectroscopy. Resonant metallic structures have successfully been designed to approach these goals. They are called optical antennas in analogy to radiofrequency (RF) antennas due to their capability to collect and control electromagnetic fields at optical frequencies. However, in contrast to the RF, where exact design rules for antennas, waveguides, and antenna-load matching in terms of their impedances are well established, substantial physical differences limit the simple extension of the RF concepts into the optical regime. Key distinctions include, for one, intrinsic material resonances including quantum state excitations (metals, metal oxides, semiconductor homo- and heterostructures) and extrinsic resonances (surface plasmon/phonon polaritons) at optical frequencies. Second, in the absence of discrete inductors, capacitors, and resistors, new design strategies must be developed to impedance match the antenna to the load, ultimately in the form of a vibrational, electronic, or spin excitation on the quantum level. Third, there is as yet a lack of standard performance metrics for characterizing, comparing and quantifying optical antenna performance. Therefore, optical antenna development is currently challenged at all the levels of design, fabrication, and characterization. Here we generalize the ideal antenna-load interaction at optical frequencies, characterized by three main steps: (i) far-field reception of a propagating mode exciting an antenna resonance, (ii) subsequent transformation of that mode into a nanoscale spatial localization, and (iii) near-field coupling via an enhanced local density of states to a quantum load. These three steps define the goal of efficient transformation of incident radiation into a quantum excitation in an impedance-matched fashion. We review the physical basis of the light-matter interaction at the transition from the RF to optical regime, discuss the extension of antenna theory as needed for the design of impedance-matched optical antenna-load coupled systems, and provide several examples of the state of the art in design strategies and suggest future extensions. We furthermore suggest new performance metrics based on the combination of electric vector field, field enhancement and capture cross section measurement to aid in comparison between different antenna designs and optimization of optical antenna performance within the physical parameter space.

A Near-Zero Refractive Index Meta-Surface Structure for Antenna Performance Improvement.

PubMed

Ullah, Mohammad Habib; Islam, Mohammad Tariqul; Faruque, Mohammad Rashed Iqbal

2013-11-06

A new meta-surface structure (MSS) with a near-zero refractive index (NZRI) is proposed to enhance the performance of a square loop antenna array. The main challenge to improve the antenna performance is increment of the overall antenna volume that is mitigated by assimilating the planar NZRI MSS at the back of the antenna structure. The proposed NZRI MSS-loaded CPW-fed (Co-Planar Waveguide) four-element array antenna is designed on ceramic-bioplastic-ceramic sandwich substrate using high-frequency structure simulator (HFSS), a finite-element-method-based simulation tool. The gain and directivity of the antenna are significantly enhanced by incorporating the NZRI MSS with a 7 × 6 set of elements at the back of the antenna structure. Measurement results show that the maximum gains of the antenna increased from 6.21 dBi to 8.25 dBi, from 6.52 dBi to 9.05 dBi and from 10.54 dBi to 12.15 dBi in the first, second and third bands, respectively. The effect of the slot configuration in the ground plane on the reflection coefficient of the antenna was analyzed and optimized. The overall performance makes the proposed antenna appropriate for UHFFM (Ultra High Frequency Frequency Modulation) telemetry-based space applications as well as mobile satellite, microwave radiometry and radio astronomy applications.

A Near-Zero Refractive Index Meta-Surface Structure for Antenna Performance Improvement

PubMed Central

Ullah, Mohammad Habib; Islam, Mohammad Tariqul; Faruque, Mohammad Rashed Iqbal

2013-01-01

A new meta-surface structure (MSS) with a near-zero refractive index (NZRI) is proposed to enhance the performance of a square loop antenna array. The main challenge to improve the antenna performance is increment of the overall antenna volume that is mitigated by assimilating the planar NZRI MSS at the back of the antenna structure. The proposed NZRI MSS-loaded CPW-fed (Co-Planar Waveguide) four-element array antenna is designed on ceramic-bioplastic-ceramic sandwich substrate using high-frequency structure simulator (HFSS), a finite-element-method-based simulation tool. The gain and directivity of the antenna are significantly enhanced by incorporating the NZRI MSS with a 7 × 6 set of elements at the back of the antenna structure. Measurement results show that the maximum gains of the antenna increased from 6.21 dBi to 8.25 dBi, from 6.52 dBi to 9.05 dBi and from 10.54 dBi to 12.15 dBi in the first, second and third bands, respectively. The effect of the slot configuration in the ground plane on the reflection coefficient of the antenna was analyzed and optimized. The overall performance makes the proposed antenna appropriate for UHFFM (Ultra High Frequency Frequency Modulation) telemetry-based space applications as well as mobile satellite, microwave radiometry and radio astronomy applications. PMID:28788376

Microwave Tissue Soldering for Immediate Wound Closure

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey; Ngo, Phong H.; Phan, Chau T.; Byerly, Diane; Dusl, John; Sognier, Marguerite A.; Carl, James

2011-01-01

A novel approach for the immediate sealing of traumatic wounds is under development. A portable microwave generator and handheld antenna are used to seal wounds, binding the edges of the wound together using a biodegradable protein sealant or solder. This method could be used for repairing wounds in emergency settings by restoring the wound surface to its original strength within minutes. This technique could also be utilized for surgical purposes involving solid visceral organs (i.e., liver, spleen, and kidney) that currently do not respond well to ordinary surgical procedures. A miniaturized microwave generator and a handheld antenna are used to deliver microwave energy to the protein solder, which is applied to the wound. The antenna can be of several alternative designs optimized for placement either in contact with or in proximity to the protein solder covering the wound. In either case, optimization of the design includes the matching of impedances to maximize the energy delivered to the protein solder and wound at a chosen frequency. For certain applications, an antenna could be designed that would emit power only when it is in direct contact with the wound. The optimum frequency or frequencies for a specific application would depend on the required depth of penetration of the microwave energy. In fact, a computational simulation for each specific application could be performed, which would then match the characteristics of the antenna with the protein solder and tissue to best effect wound closure. An additional area of interest with potential benefit that remains to be validated is whether microwave energy can effectively kill bacteria in and around the wound. Thus, this may be an efficient method for simultaneously sterilizing and closing wounds.

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

Analysis of Satellite Communications Antenna Patterns

NASA Technical Reports Server (NTRS)

Rahmat-Samii, Y.

1985-01-01

Computer program accurately and efficiently predicts far-field patterns of offset, or symmetric, parabolic reflector antennas. Antenna designer uses program to study effects of varying geometrical and electrical (RF) parameters of parabolic reflector and its feed system. Accurate predictions of far-field patterns help designer predict overall performance of antenna. These reflectors used extensively in modern communications satellites and in multiple-beam and low side-lobe antenna systems.

Multiple Antenna Implementation System (MAntIS)

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

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

1993-01-01

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

Analysis of single band and dual band graphene based patch antenna for terahertz region

NASA Astrophysics Data System (ADS)

George, Jemima Nissiyah; Madhan, M. Ganesh

2017-10-01

A microstrip patch antenna is designed using a very thin layer of graphene as the radiating patch, which is fed by a microstrip transmission line. The graphene based patch is designed on a silicon substrate having a dielectric constant of 11.9, to radiate at a single frequency of 2.6 THz. Further, this antenna is made to resonate at dual frequencies of 2.48 THz and 3.35 THz, by changing the substrate height, which is reported for the first time. Various antenna parameters such as return loss, VSWR, gain, efficiency and bandwidth are also determined for the single and dual band operation. For the single band operation, a bandwidth of 145.4 GHz and an efficiency of 92% was achieved. For dual band operation, a maximum bandwidth of 140.5 GHz was obtained at 3.35 THz and an efficiency of 87.3% was obtained at the first resonant frequency of 2.48 THz. The absorption cross section of the antenna is also analysed for various substrate heights and has maximum peaks at the corresponding resonating frequencies. The simulation has been carried out by using a full wave electromagnetic simulator based on FDTD method.

Performance assessment of the antenna setup for the ITER plasma position reflectometry in-vessel systems.

PubMed

Varela, P; Belo, J H; Quental, P B

2016-11-01

The design of the in-vessel antennas for the ITER plasma position reflectometry diagnostic is very challenging due to the need to cope both with the space restrictions inside the vacuum vessel and with the high mechanical and thermal loads during ITER operation. Here, we present the work carried out to assess and optimise the design of the antenna. We show that the blanket modules surrounding the antenna strongly modify its characteristics and need to be considered from the early phases of the design. We also show that it is possible to optimise the antenna performance, within the design restrictions.

Design of inside cut von koch fractal UWB MIMO antenna

NASA Astrophysics Data System (ADS)

Tharani, V.; Shanmuga Priya, N.; Rajesh, A.

2017-11-01

An Inside Cut Hexagonal Von Koch fractal MIMO antenna is designed for UWB applications and its characteristics behaviour are studied. Self-comparative and space filling properties of Koch fractal structure are utilized in the antenna design which leads to the desired miniaturization and wideband characteristics. The hexagonal shaped Von Koch Fractal antenna with Defected Ground Structure (DGS) is designed on FR4 substrate with a compact size of 30mm x 20mm x 1.6mm. The antenna achieves a maximum of -44dB and -51dB at 7.1GHz for 1-element and 2-element case respectively.

Telecommunications Antennas for the Juno Mission to Jupiter

NASA Technical Reports Server (NTRS)

Vacchione, Joseph D.; Kruid, Ronald C.; Prata, Aluizio, Jr.; Amaro, Luis R.; Mittskus, Anthony P.

2012-01-01

The Juno Mission to Jupiter requires a full sphere of coverage throughout its cruise to and mission at Jupiter. This coverage is accommodated through the use of five (5) antennas; forward facing low gain, medium gain, and high gain antennas, and an aft facing low gain antenna along with an aft mounted low gain antenna with a torus shaped antenna pattern. Three of the antennas (the forward low and medium gain antennas) are classical designs that have been employed on several prior NASA missions. Two of the antennas employ new technology developed to meet the Juno mission requirements. The new technology developed for the low gain with torus shaped radiation pattern represents a significant evolution of the bicone antenna. The high gain antenna employs a specialized surface shaping designed to broaden the antenna's main beam at Ka-band to ease the requirements on the spacecraft's attitude control system.

Technology needs of advanced Earth observation spacecraft

NASA Technical Reports Server (NTRS)

Herbert, J. J.; Postuchow, J. R.; Schartel, W. A.

1984-01-01

Remote sensing missions were synthesized which could contribute significantly to the understanding of global environmental parameters. Instruments capable of sensing important land and sea parameters are combined with a large antenna designed to passively quantify surface emitted radiation at several wavelengths. A conceptual design for this large deployable antenna was developed. All subsystems required to make the antenna an autonomous spacecraft were conceptually designed. The entire package, including necessary orbit transfer propulsion, is folded to package within the Space Transportation System (STS) cargo bay. After separation, the antenna, its integral feed mast, radiometer receivers, power system, and other instruments are automatically deployed and transferred to the operational orbit. The design resulted in an antenna with a major antenna dimension of 120 meters, weighing 7650 kilograms, and operating at an altitude of 700 kilometers.

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.

The development of the miniaturized waveform receiver with the function measuring Antenna Impedance in space plasmas

NASA Astrophysics Data System (ADS)

Ishii, H.; Kojima, H.; Fukuhara, H.; Okada, S.; Yamakawa, H.

2012-04-01

Plasma wave is one of the most essential physical quantities in the solar terrestrial physics. The role of plasma wave receiver onboard satellites is to detect plasma waves in space with a good signal to noise ratio. There are two types of plasma wave receivers, the sweep frequency analyzer and the waveform capture. While the sweep frequency analyzer provides plasma wave spectra, the waveform capture obtains waveforms with phase information that is significant in studying nonlinear phenomena. Antenna sensors to observe electric fields of the plasma waves show different features in plasmas from in vacuum. The antenna impedances have specific characteristics in the frequency domain because of the dispersion of plasmas. These antenna impedances are expressed with complex number. We need to know not only the antenna impedances but also the transfer functions of plasma wave receiver's circuits in order to calibrate observed waveforms precisely. The impedances of the electric field antennas are affected by a state of surrounding plasmas. Since satellites run through various regions with different plasma parameters, we precisely should measure the antenna impedances onboard spacecraft. On the contrary, we can obtain the plasma density and by measuring the antenna impedances. Several formulas of the antenna impedance measurement system were proposed. A synchronous detection method is used on the BepiColombo Mercury Magnetospheric Orbiter (MMO), which will be launched in 2014. The digital data are stored in the onboard memory. They are read out and converted to the analog waveforms by D/A converter. They are fed into the input of the preamplifiers of antenna sensors through a resistor. We can calculate a transfer function of the circuit by applying the synchronous detection method to the output waveform from waveform receivers and digital data as a signal source. The size of this system is same as an A5 board. In recent years, Application Specific Integrated Circuit (ASIC) is in attention which is a technique to integrate large scale and complicated circuits. Lots of ASICs have been applied to high energy astrophysics. In this paper, we show our attempt to miniaturize the antennas impedances measurement system and Waveform Capture using the analogue ASIC. We design 8bits segment D/A converter that is implemented inside the waveform receiver ASIC chip. We improve input logic of the D/A converter to generate very weak signals accurately. The designed chip realizes the measurement of the antenna impedance as well as the waveform observation in the board size of business cards.

Adaptive antenna arrays for satellite communications: Design and testing

NASA Technical Reports Server (NTRS)

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

1985-01-01

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

Design and construction of prototype radio antenna for shortest radio wavelengths

NASA Technical Reports Server (NTRS)

Leighton, R. B.

1975-01-01

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

Directional microwave applicator and methods

NASA Technical Reports Server (NTRS)

Fink, Patrick W. (Inventor); Lin, Greg Y. (Inventor); Chu, Andrew W. (Inventor); Dobbins, Justin A. (Inventor); Arndt, G. Dickey (Inventor); Ngo, Phong H. (Inventor)

2008-01-01

A miniature microwave antenna is disclosed which may be utilized for biomedical applications such as, for example, radiation induced hyperthermia through catheter systems. One feature of the antenna is that it possesses azimuthal directionality despite its small size. This directionality permits targeting of certain tissues while limiting thermal exposure of adjacent tissue. One embodiment has an outer diameter of about 0.095'' (2.4 mm) but the design permits for smaller diameters.

Beyond dipolar regime in high-order plasmon mode bowtie antennas

NASA Astrophysics Data System (ADS)

Cuche, Aurélien; Viarbitskaya, Sviatlana; Kumar, Upkar; Sharma, Jadab; Arbouet, Arnaud; Girard, Christian; Dujardin, Erik

2017-03-01

Optical nanoantennas have shown their great potential for far-field to near-field coupling and for light confinement in subwavelength volumes. Here, we report on a multimodal configuration for bright and polarization-dependent bowtie antenna based on large and highly crystalline gold prisms. Each individual prism constituting an antenna arm sustains high order plasmon modes in the visible and near infrared range that allow for high field confinement and two-dimensional optical information propagation. We demonstrate by scanning two-photon luminescence (TPL) microscopy and numerical simulations based on the Green dyadic method that these bowtie antennas result in intense hot spots in different antenna locations as a function of the incident polarization. Finally, we quantify the local field enhancement above the antennas by computing the normalized total decay rate of a molecular system placed in the near field of the antenna gap as a function of the dipole orientation. We demonstrate the existence of a subtle relation between antenna geometry, polarization dependence and field enhancement. These new multimodal optical antennas are excellent far field to near field converter and they open the door for new strategies in the design of coplanar optical components for a wide range of applications including sensing, energy conversion or integrated information processing.

Design of a Class of Antennas Utilizing MEMS, EBG and Septum Polarizers including Near-field Coupling Analysis

NASA Astrophysics Data System (ADS)

Kim, Ilkyu

Recent developments in mobile communications have led to an increased appearance of short-range communications and high data-rate signal transmission. New technologies provides the need for an accurate near-field coupling analysis and novel antenna designs. An ability to effectively estimate the coupling within the near-field region is required to realize short-range communications. Currently, two common techniques that are applicable to the near-field coupling problem are 1) integral form of coupling formula and 2) generalized Friis formula. These formulas are investigated with an emphasis on straightforward calculation and accuracy for various distances between the two antennas. The coupling formulas are computed for a variety of antennas, and several antenna configurations are evaluated through full-wave simulation and indoor measurement in order to validate these techniques. In addition, this research aims to design multi-functional and high performance antennas based on MEMS (Microelectromechanical Systems) switches, EBG (Electromagnetic Bandgap) structures, and septum polarizers. A MEMS switch is incorporated into a slot loaded patch antenna to attain frequency reconfigurability. The resonant frequency of the patch antenna can be shifted using the MEM switch, which is actuated by the integrated bias networks. Furthermore, a high gain base-station antenna utilizing beam-tilting is designed to maximize gain for tilted beam applications. To realize this base-station antenna, an array of four dipole-EBG elements is constructed to implement a fixed down-tilt main beam with application in base station arrays. An improvement of the operating range with the EBG-dipole array is evaluated using a simple linkbudget analysis. The septum polarizer has been widely used in circularly polarized antenna systems due to its simple and compact design and high quality of circularity. In this research, the sigmoid function is used to smoothen the edge in the septum design, which makes it suitable for HPM systems. The PSO (Particle Swarm Optimization) technique is applied to the septum design to achieve a high performance antenna design. The electric field intensity above the septum is evaluated through the simulation and its properties are compared to simple half-plane scattering phenomena.

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.

The ITER ICRF Antenna Design with TOPICA

NASA Astrophysics Data System (ADS)

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

2007-11-01

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

Radiation and scattering from printed antennas on cylindrically conformal platforms

NASA Technical Reports Server (NTRS)

Kempel, Leo C.; Volakis, John L.; Bindiganavale, Sunil

1994-01-01

The goal was to develop suitable methods and software for the analysis of antennas on cylindrical coated and uncoated platforms. Specifically, the finite element boundary integral and finite element ABC methods were employed successfully and associated software were developed for the analysis and design of wraparound and discrete cavity-backed arrays situated on cylindrical platforms. This work led to the successful implementation of analysis software for such antennas. Developments which played a role in this respect are the efficient implementation of the 3D Green's function for a metallic cylinder, the incorporation of the fast Fourier transform in computing the matrix-vector products executed in the solver of the finite element-boundary integral system, and the development of a new absorbing boundary condition for terminating the finite element mesh on cylindrical surfaces.

Autonomous antenna tracking system for mobile symphonie ground stations

NASA Technical Reports Server (NTRS)

Ernsberger, K.; Lorch, G.; Waffenschmidt, E.

1982-01-01

The implementation of a satellite tracking and antenna control system is described. Due to the loss of inclination control for the symphonie satellites, it became necessary to equip the parabolic antennas of the mobile Symphonie ground station with tracking facilities. For the relatively low required tracking accuracy of 0.5 dB, a low cost, step track system was selected. The step track system developed for this purpose and tested over a long period of time in 7 ground stations is based on a search step method with subsequent parabola interpolation. As compared with the real search step method, the system has the advantage of a higher pointing angle resolution, and thus a higher tracking accuracy. When the pilot signal has been switched off for a long period of time, as for instance after the eclipse, the antenna is repointed towards the satellite by an automatically initiated spiral search scan. The function and design of the tracking system are detailed, while easy handling and tracking results.

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.

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.

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.

Analysis of Alternative Ring Resonator Designs

DTIC Science & Technology

2014-08-01

the ring strip of the antenna as in the case of the original design. Both the alternative dielectric laminate and the increased thickness laminate...adjustments to the geometry parameters. 2. Ring Resonator Antenna Design The ring resonator is a two port antenna consisting of a ring strip and two...for various soil sample depths indicates that most of the measureable response is from within 2 mm of the resonator antenna strip surface. For the

Ultra-Small Dualband Dualmode Microstrip Antenna Based on Novel Hybrid Resonator

NASA Astrophysics Data System (ADS)

Zhu, Ji-Xu; Bai, Peng; Zheng, Hao-Zhong

2016-11-01

A novel hybrid resonator consists of right handed patch+composite right and left handed transmission line (RH+CRLH) is proposed for the first time aiming at both compactness and frequency manipulation. A demonstration with theoretical dispersion relations and EM simulation is provided for the correctness and efficiency. According to the new method, an ultra-small and dualband antenna operating around 2.4 GHz (n=0, Bluetooth band) and 3.5 GHz (n=+1, Wimax band) is designed, fabricated and measured, whose occupied area is only of 0.158 λ_0. Numerical and experimental results indicate that the antenna exhibits a good impendence match, low cross-polarization and comparable radiation gains in both bands. Excellent performances of the antennas based on hybrid resonators predict promising applications in multifunction wireless communication systems.

Design of one-kilometer-long antenna sticks and support structure for a geosynchronous satellite

NASA Astrophysics Data System (ADS)

Freeman, Janet Elizabeth

This study develops a preliminary structural design for three one-kilometer-long antenna sticks and an antenna support structure for a geosynchronous earth-imaging satellite. On each of the antenna sticks is mounted a linear array of over 16,000 antenna elements. The antenna sticks are parallel to each other, and are spaced 1 km apart so that they form the corners of an imaginary triangular tube. This tube is spinning about its long axis. Antenna performance requires that the position of each antenna element be known to an accuracy of 0.5 cm, and that the spacecraft's spin axis be parallel to the earth's spin axis within one degree. Assuming that the position of each joint on each antenna stick is known, the antenna sticks are designed as beams under a uniformly distributed acceleration (due to spacecraft spin) to meet the displacement accuracy requirements for the antenna elements. Both a thin-walled round tube and a three-longeron double-laced truss are considered for the antenna stick structure. A spacecraft spinrate is chosen by considering the effects of environmental torques on the precession of a simplified spacecraft. A preliminary truss-like support structure configuration is chosen, and analyzed in quasi-static equilibrium with control thrusters firing to estimate the axial loads in the structural members. The compressive loads found by this analysis are used to design the support structure members to be buckling-critical three-longeron double-laced truss columns. Some tension-only members consisting of Kevlar cord are included in the design to eliminate the need for bulkier members. The lateral vibration modes of the individual structural members are found by conventional analysis -- the fundamental frequencies are as low as 0.0066 Hz. Finite element dynamic analyses of the structure in free vibration confirm that simplified models of the structure and members can be used to determine the structural modes and natural frequencies for design purposes.

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.

Machine-Learning Approach for Design of Nanomagnetic-Based Antennas

NASA Astrophysics Data System (ADS)

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

2017-08-01

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

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

NASA Technical Reports Server (NTRS)

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

2015-01-01

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

Design of a Forward Looking Synthetic Aperture Radar for an Autonomous Cryobot for Subsurface Exploration of Europa and Enceladus

NASA Astrophysics Data System (ADS)

Pradhan, O.; Gasiewski, A. J.; Stone, W.

2017-12-01

We present the design, analyses and field testing of a forward-looking endfire synthetic aperture radar (SAR) for the `Very deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice explorer' (VALKYRIE) ice-penetrating cryobot. This design demonstrates critical technologies that will support an eventual landing and ice penetrating mission to Jupiter's icy moon, Europa. The project consists of (1) design of an array of four conformal cavity-backed log-periodic folded slot dipole array (LPFSA) antennas that form the radiating elements, (2) design of a radar system that includes RF signal generation, 4x4 transmit-receive antenna switching and isolation and digital SAR data processing and (3) field testing of the SAR system. The antennas were designed, fabricated, and lab tested at the Center for Environmental Technology (CET) at CU-Boulder. The radar analog and digital system were also designed and integrated at CET utilizing rugged RF components and FPGA based digital waveform generation. Field testing was performed in conjunction with VALKYRIE tests by Stone Aerospace in June, 2015 on Matanuska Glacier, Alaska. In this presentation we will describe in detail the following aspects pertaining to the design, analysis and testing of the endfire SAR system; (1) Waveform generation capability of the radar as well as transmit and receive channel calibration (2) Theoretical analysis of the radial resolution improvement made possible by using the radar in an endfire SAR mode along with the free space radar tests performed to validate the proposed endfire SAR system (3) A method for azimuth ambiguity resolution by operating the endfire SAR in a bistatic mode (4) Modal analysis of the layered cylindrical LPFSA antenna structure and a forward model of the wave propagation path through planar layered ice medium and (5) Analysis and interpretation of the in-situ measurements of the antennas and endfire SAR operation on the Matanuska glacier.

A switchable magnetic low-index metamaterial for use in a dynamically reconfigurable beam-scanning lens antenna with a single feed

NASA Astrophysics Data System (ADS)

Turpin, Jeremiah Paul

Metamaterials and Transformation Optics (TO) have been used to design and implement many novel electromagnetic devices that can achieve effects not possible using conventional materials. Compact high-gain antennas are one of the more popular and successful emerging applications for the new TO and metamaterial design approaches. This dissertation details an extension of uniaxial near-zero-index metamaterial lenses through the incorporation of a tunable or reconfigurable metamaterial as a replacement for the static metamaterial of the original antenna. A design is presented for a beam-scanning TO lens that allows an arbitrary number of beams at controlled magnitudes to be dynamically synthesized from a single omnidirectional source, unlike the equivalent antenna constructed using an array. A cylindrical slab of zero-index magnetic metamaterial controls the radiation pattern by altering the effective shape of the lens through switching of selected regions 'off' to emulate free-space conditions. A design for a switchable metamaterial is presented that allows for digital control over its bulk properties, from near-zero-index to near-free-space at the targeted operational frequency. Extensive modeling and simulations were performed for the design of the lens and metamaterial and during the analysis of measurement results. Initial prototypes of the tunable metamaterial were fabricated and characterized to confirm the original measurements, and the design updated to incorporate the measured data. These measurements were performed using custom test fixtures manufactured specifically for this project. Finally, a simplified prototype lens was manufactured and characterized in an anechoic as a proof-of-concept for the design. This dissertation presents the lens and metamaterial specifications, as well as the design process and considerations that were determined for practical tunable and reconfigurable metamaterials. Although the focus is on the particular example of the beam-scanning reconfigurable antenna, the analysis and modeling methods presented here are applicable to any reconfigurable metamaterial application.

Application of Metamaterials to RF Energy Harvesting and Infrared Photodetection

NASA Astrophysics Data System (ADS)

Fowler, Clayton M.

Techniques for adapting metamaterials for the improvement of RF energy harvesting and infrared photodetection are demonstrated using experimental and computer simulation methods. Two methods for RF energy harvesting are experimentally demonstrated and supported by computer simulation. In the first method, a metamaterial perfect absorber (MPA) is made into a rectenna capable of harvesting RF energy and delivering power to a load by soldering Schottky diodes onto connected split ring resonator (SRR) structures composing the planar metasurface of the perfect absorber. The metamaterial rectenna is accompanied by a ground plane placed parallel to it, which forms a Fabry-Perot cavity between the metasurface and the ground plane. The Fabry-Perot cavity stores energy in the form of standing waves which is transferred to the SRR structures of the metasurface as AC currents that are rectified by the diodes to create DC power. This type of design enables highly efficient energy harvesting for low input power, creates a large antenna capture area, and uses elements with small electrical size, such that 100 uW of power (enough to operate simple devices) can be captured at ambient intensities 1 - 2 uW/cm2. Two designs using this method are presented, one that operates for linear polarizations at 0.9 GHz and a smaller polarization-independent design that operates around 1.5 GHz. In the second method, the energy stored in the standing waves of an MPA Fabry-Perot cavity is instead harvested by placing a separate energy harvesting antenna within the cavity. The cavity shapes and enhances the incident electric field, and then the separate energy harvesting antenna is designed to be inserted into the cavity so that its shape and/or radiation pattern matches the electric field lines within the cavity and maximally extracts the stored energy. This method allows for great customization of antenna design parameters, such as operating frequency, polarization dependence, and directionality, by swapping out different metasurface and antenna designs. Using this method, the amount of power harvested by a simple dipole rectenna placed within a cavity is improved by a factor of 18 as compared to what it would harvest by itself at an ambient intensity of 35 nW/cm2. Lastly, the addition of plasmonic structures to DWELL (quantum dot-in-a-well) infrared photodetectors is investigated by computer simulation. DWELL photodetectors have the potential to one day replace standard mercury cadmium telluride detectors by being cheaper alternatives with a higher operating temperature. The inclusion of gold plasmonic structure arrays into DWELL detectors enables excitation of surface plasmon polariton modes that increase the responsivity of the detector to incident infrared radiation. The peak responsivity of a DWELL detector is demonstrated to improve by a factor of 8 for a 1 mum thick layer of plasmonic structures and by a factor of 15 for a 2 mum thick layer. These works are steps forward in making RF energy harvesting practically useful and for improving infrared photodetector performance.

Waveform Optimization for Target Estimation by Cognitive Radar with Multiple Antennas.

PubMed

Yao, Yu; Zhao, Junhui; Wu, Lenan

2018-05-29

A new scheme based on Kalman filtering to optimize the waveforms of an adaptive multi-antenna radar system for target impulse response (TIR) estimation is presented. This work aims to improve the performance of TIR estimation by making use of the temporal correlation between successive received signals, and minimize the mean square error (MSE) of TIR estimation. The waveform design approach is based upon constant learning from the target feature at the receiver. Under the multiple antennas scenario, a dynamic feedback loop control system is established to real-time monitor the change in the target features extracted form received signals. The transmitter adapts its transmitted waveform to suit the time-invariant environment. Finally, the simulation results show that, as compared with the waveform design method based on the MAP criterion, the proposed waveform design algorithm is able to improve the performance of TIR estimation for extended targets with multiple iterations, and has a relatively lower level of complexity.

Antennas for Terahertz Applications: Focal Plane Arrays and On-chip Non-contact Measurement Probes

NASA Astrophysics Data System (ADS)

Trichopoulos, Georgios C.

The terahertz (THz) band provides unique sensing opportunities that enable several important applications such as biomedical imaging, remote non-destructive inspection of packaged goods, and security screening. THz waves can penetrate most materials and can provide unique spectral information in the 0.1--10 THz band with high resolution. In contrast, other imaging modalities, like infrared (IR), suffer from low penetration depths and are thus not attractive for non-destructive evaluation. However, state-of-the-art THz imaging systems typically employ mechanical raster scans using a single detector to acquire two-dimensional images. Such devices tend to be bulky and complicated due to the mechanical parts, and are thus rather expensive to develop and operate. Thus, large-format (e.g. 100x100 pixels) and all-electronics based THz imaging systems are badly needed to alleviate the space, weight and power (SWAP) factors and enable cost effective utilization of THz waves for sensing and high-data-rate communications. In contrast, photonic sensors are very compact because light can couple directly to the photodiode without residing to radiation coupling topologies. However, in the THz band, due to the longer wavelengths and much lower photon energies, highly efficient antennas with optimized input impedance have to be integrated with THz sensors. Here, we implement novel antenna engineering techniques that are optimized to take advantage of recent technological advances in solid-state THz sensing devices. For example, large-format focal plane arrays (FPAs) have been the Achilles' heel of THz imaging systems. Typically, optical components (lenses, mirrors) are employed in order to improve the optical performance of FPAs, however, antenna sensors suffer from degraded performance when they are far from the optical axis, thus minimizing the number of useful FPA elements. By modifying the radiation pattern of FPA antennas we manage to alleviate the off-axis aberration. Additionally, a butterfly-shaped antenna layout is introduced that enables broadband imaging. The alternative design presented here, allows for video-rate imaging in the 0.6--1.2 THz band and maintains a small antenna footprint, resulting in densely packed FPAs. In both antenna designs, we optimize the impedance matching between the antennas and the integrated electronic devices, thus achieving optimum responsivity levels for high sensitivity and low noise performance. Subsequently, we present the design details of the first THz camera and the first THz camera images captured. With the realized THz camera, imaging of concealed objects is achieved with <1mm diffraction limited spatial resolution. Moreover, motivated by the THz camera's real-time image acquisition, we developed the first camera-based THz computer tomography system that allows rapid cross-sectional imaging (˜2 min). For the design and analysis of the THz camera performance, we developed an in-house hybrid electromagnetic model, combining full-wave and high-frequency computational methods. The antenna radiation and impedance computation is first carried out using full-wave modeling of the FPA. Subsequently, we employ scalar diffraction theory to compute the field distribution at any point in space. Thus, the hybrid electromagnetic model allows fast and accurate design of THz antennas and modeling of the complete THz imaging system. Finally, motivated by the novel THz antenna layouts and the quasioptical techniques, we developed a novel non-contact probe measurement method for on-chip device characterization. In the THz regime, traditional contact probes are too small and fragile, thus inhibiting accurate and reliable circuit measurements. By integrating the device under test (DUT) with THz antennas that act as the measurement probes, we may couple the incident and reflected signal from and to the network analyzer without residing to any physical connection.

Performance of a family of omni and steered antennas for mobile satellite applications

NASA Technical Reports Server (NTRS)

Woo, K.; Huang, J.; Jamnejad, V.; Bell, D.; Berner, J.; Estabrook, P.; Densmore, A.

1990-01-01

The design and performance of a family of vehicle antennas developed at JPL in support of an emerging US Mobile Satellite Service (MSS) system are described. Test results of the antennas are presented. Trends for future development are addressed. Recommendations on design approaches for vehicle antennas of the first generation MSS are discussed.

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

Tunable, Electrically Small, Inductively Coupled Antenna for Transportable Ionospheric Heating

NASA Astrophysics Data System (ADS)

Esser, Benedikt; Mauch, Daniel; Dickens, James; Mankowski, John; Neuber, Andreas

2018-04-01

An electrically small antenna is evaluated for use as the principle radiating element in a mobile ionospheric heating array. Consisting of a small loop antenna inductively coupled to a capacitively loaded loop, the electrically small antenna provides high efficiency with the capability of being tuned within the range of ionospheric heating. At a factor 60 smaller in area than a High-Frequency Active Auroral Research Program element, this antenna provides a compact, efficient radiating element for mobile ionospheric heating. A prototype antenna at 10 MHz was built to study large-scale feasibility and possible use with photoconductive semiconductor switch-based drivers. Based on the experimental study, the design has been extrapolated to a small 6 × 4 array of antennas. At a total power input of 16.1 MW this array is predicted to provide 3.6-GW effective radiated power typically required for ionospheric heating. Array cross talk is addressed, including effects upon individual antenna port parameters. Tuning within the range of ionospheric heating, 3-10 MHz, is made possible without the use of lossy dielectrics through a large capacitive area suited to tune the antenna. Considerations for high power operation across the band are provided including a method of driving the antenna with a simple switcher requiring no radio frequency cabling. Source matching may be improved via adjustment of the coupling between small loop antenna and capacitively loaded loop improving |S11| from -1 to -21 dB at 3 MHz.

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

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

PubMed Central

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

2014-01-01

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

Design of Vivaldi Microstrip Antenna for Ultra-Wideband Radar Applications

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

Design of Ultra-Wideband Tapered Slot Antenna by Using Binomial Transformer with Corrugation

NASA Astrophysics Data System (ADS)

Chareonsiri, Yosita; Thaiwirot, Wanwisa; Akkaraekthalin, Prayoot

2017-05-01

In this paper, the tapered slot antenna (TSA) with corrugation is proposed for UWB applications. The multi-section binomial transformer is used to design taper profile of the proposed TSA that does not involve using time consuming optimization. A step-by-step procedure for synthesis of the step impedance values related with step slot widths of taper profile is presented. The smooth taper can be achieved by fitting the smoothing curve to the entire step slot. The design of TSA based on this method yields results with a quite flat gain and wide impedance bandwidth covering UWB spectrum from 3.1 GHz to 10.6 GHz. To further improve the radiation characteristics, the corrugation is added on the both edges of the proposed TSA. The effects of different corrugation shapes on the improvement of antenna gain and front-to-back ratio (F-to-B ratio) are investigated. To demonstrate the validity of the design, the prototypes of TSA without and with corrugation are fabricated and measured. The results show good agreement between simulation and measurement.

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

NASA Technical Reports Server (NTRS)

Milne, R.

1995-01-01

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

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Topology Design for Directional Range Extension Networks with Antenna Blockage

DTIC Science & Technology

2017-03-19

introduced by pod-based antenna blockages. Using certain modeling approximations, the paper presents a quantitative analysis showing design trade-offs...parameters. Sec- tion IV develops quantitative relationships among key design elements and performance metrics. Section V considers some implications of the...Topology Design for Directional Range Extension Networks with Antenna Blockage Thomas Shake MIT Lincoln Laboratory shake@ll.mit.edu Abstract

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.

Front-end antenna system design for the ITER low-field-side reflectometer system using GENRAY ray tracing.

PubMed

Wang, G; Doyle, E J; Peebles, W A

2016-11-01

A monostatic antenna array arrangement has been designed for the microwave front-end of the ITER low-field-side reflectometer (LFSR) system. This paper presents details of the antenna coupling coefficient analyses performed using GENRAY, a 3-D ray tracing code, to evaluate the plasma height accommodation capability of such an antenna array design. Utilizing modeled data for the plasma equilibrium and profiles for the ITER baseline and half-field scenarios, a design study was performed for measurement locations varying from the plasma edge to inside the top of the pedestal. A front-end antenna configuration is recommended for the ITER LFSR system based on the results of this coupling analysis.

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.

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

NASA Technical Reports Server (NTRS)

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

1976-01-01

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

47 CFR 73.316 - FM antenna systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 4 2012-10-01 2012-10-01 false FM antenna systems. 73.316 Section 73.316... Broadcast Stations § 73.316 FM antenna systems. (a) It shall be standard to employ horizontal polarization...) Directional antennas. A directional antenna is an antenna that is designed or altered for the purpose of...

47 CFR 73.316 - FM antenna systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 4 2014-10-01 2014-10-01 false FM antenna systems. 73.316 Section 73.316... Broadcast Stations § 73.316 FM antenna systems. (a) It shall be standard to employ horizontal polarization...) Directional antennas. A directional antenna is an antenna that is designed or altered for the purpose of...

47 CFR 73.316 - FM antenna systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false FM antenna systems. 73.316 Section 73.316... Broadcast Stations § 73.316 FM antenna systems. (a) It shall be standard to employ horizontal polarization...) Directional antennas. A directional antenna is an antenna that is designed or altered for the purpose of...

47 CFR 73.316 - FM antenna systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 4 2011-10-01 2011-10-01 false FM antenna systems. 73.316 Section 73.316... Broadcast Stations § 73.316 FM antenna systems. (a) It shall be standard to employ horizontal polarization...) Directional antennas. A directional antenna is an antenna that is designed or altered for the purpose of...

47 CFR 73.316 - FM antenna systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 4 2013-10-01 2013-10-01 false FM antenna systems. 73.316 Section 73.316... Broadcast Stations § 73.316 FM antenna systems. (a) It shall be standard to employ horizontal polarization...) Directional antennas. A directional antenna is an antenna that is designed or altered for the purpose of...

Design and verification of mechanisms for a large foldable antenna

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

Antenna system for MSAT mission

NASA Technical Reports Server (NTRS)

Karlsson, Ingmar; Patenaude, Yves; Stipelman, Leora

1988-01-01

Spar has evaluated and compared several antenna concepts for the North American Mobile Satellite. The paper describes some of the requirements and design considerations for the antennas and demonstrates the performance of antenna concepts that can meet them. Multiple beam reflector antennas are found to give best performance and much of the design effort has gone into the design of the primary feed radiators and beam forming networks to achieve efficient beams with good overlap and flexibility. Helices and cup dipole radiators have been breadboarded as feed element candidates and meausured results are presented. The studies and breadboard activities have made it possible to proceed with a flight program.

Antenna design for propagating spin wave spectroscopy in ferromagnetic thin films

NASA Astrophysics Data System (ADS)

Zhang, Yan; Yu, Ting; Chen, Ji-lei; Zhang, You-guang; Feng, Jian; Tu, Sa; Yu, Haiming

2018-03-01

In this paper, we investigate the characteristics of antenna for propagating-spin-wave-spectroscopy (PSWS) experiment in ferromagnetic thin films. Firstly, we simulate the amplitude and phase distribution of the high-frequency magnetic field around antenna by high frequency structure simulator (HFSS). And then k distribution of the antenna is obtained by fast Fourier transformation (FFT). Furthermore, three kinds of antenna designs, i.e. micro-strip line, coplanar waveguide (CPW), loop, are studied and compared. How the dimension parameter of antenna influence the corresponding high-frequency magnetic field amplitude and k distribution are investigated in details.

Inflatable antenna for earth observing systems

NASA Astrophysics Data System (ADS)

Wang, Hong-Jian; Guan, Fu-ling; Xu, Yan; Yi, Min

2010-09-01

This paper describe mechanical design, dynamic analysis, and deployment demonstration of the antenna , and the photogrammetry detecting RMS of inflatable antenna surface, the possible errors results form the measurement are also analysed. Ticra's Grasp software are used to predict the inflatable antenna pattern based on the coordinates of the 460 points on the parabolic surface, the final results verified the whole design process.

Smart skin spiral antenna with chiral absorber

NASA Astrophysics Data System (ADS)

Varadan, Vijay K.; Varadan, Vasundara V.

1995-05-01

Recently there has been considerable interest toward designing 'smart skins' for aircraft. The smart skin is a composite layer which may contain conformal radars, conformal microstrip antennas or spiral antennas for electromagnetic applications. These embedded antennas will give rise to very low radar cross section (RCS) or can be completely 'hidden' to tracking radar. In addition, they can be used to detect, monitor or even jam other unwanted electromagnetic field signatures. This paper is designed to address some technical advances made to reduce the size of spiral antennas using tunable dielectric materials and chiral absorbers. The purpose is to design, develop and fabricate a thin, wideband, conformal spiral antenna architecture that is structurally integrable and which uses advanced Penn State dielectric and absorber materials to achieve wideband ground planes, and together with low RCS. Traditional practice has been to design radome and antenna as separate entities and then resolve any interface problems during an integration phase. A structurally integrable conformal antenna, however, demands that the functional components be highly integrated both conceptually and in practice. Our concept is to use the lower skin of the radome as a substrate on which the radiator can be made using standard photolithography, thick film or LTCC techniques.

An adaptive array antenna for mobile satellite communications

NASA Technical Reports Server (NTRS)

Milne, Robert

1990-01-01

The design of an adaptive array antenna for land vehicle operation and its performance in an operational satellite system is described. Linear and circularly polarized antenna designs are presented. The acquisition and tracking operation of a satellite is described and the effect on the communications signal is discussed. A number of system requirements are examined that have a major impact on the antenna design. The results of environmental, power handling, and RFI testing are presented and potential problems are identified.

S/Ka Dichroic Plate with Rounded Corners for NASA's 34-m Beam-Waveguide Antenna

NASA Astrophysics Data System (ADS)

Veruttipong, W.; Khayatian, B.; Imbriale, W.

2016-02-01

An S-/Ka-band frequency selective surface (FSS) or a dichroic plate is designed, manufactured, and tested for use in NASA's Deep Space Network (DSN) 34-m beam-waveguide (BWG) antennas. Due to its large size, the proposed dichroic incorporates a new design feature: waveguides with rounded corners to cut cost and allow ease of manufacturing the plate. The dichroic is designed using an analysis that combines the finite-element method (FEM) for arbitrarily shaped guides with the method of moments and Floquet mode theory for periodic structures. The software was verified by comparison with previously measured and computed dichroic plates. The large plate was manufactured with end-mill machining. The RF performance was measured and is in excellent agreement with the analytical results. The dichroic has been successfully installed and is operational at DSS-24, DSS-34, and DSS-54.

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.

Toward imaging the body at 10.5 tesla.

PubMed

Ertürk, M Arcan; Wu, Xiaoping; Eryaman, Yiğitcan; Van de Moortele, Pierre-François; Auerbach, Edward J; Lagore, Russell L; DelaBarre, Lance; Vaughan, J Thomas; Uğurbil, Kâmil; Adriany, Gregor; Metzger, Gregory J

2017-01-01

To explore the potential of performing body imaging at 10.5 Tesla (T) compared with 7.0T through evaluating the transmit/receive performance of similarly configured dipole antenna arrays. Fractionated dipole antenna elements for 10.5T body imaging were designed and evaluated using numerical simulations. Transmit performance of antenna arrays inside the prostate, kidneys and heart were investigated and compared with those at 7.0T using both phase-only radiofrequency (RF) shimming and multi-spoke pulses. Signal-to-noise ratio (SNR) comparisons were also performed. A 10-channel antenna array was constructed to image the abdomen of a swine at 10.5T. Numerical methods were validated with phantom studies at both field strengths. Similar power efficiencies were observed inside target organs with phase-only shimming, but RF nonuniformity was significantly higher at 10.5T. Spokes RF pulses allowed similar transmit performance with accompanying local specific absorption rate increases of 25-90% compared with 7.0T. Relative SNR gains inside the target anatomies were calculated to be >two-fold higher at 10.5T, and 2.2-fold SNR gain was measured in a phantom. Gradient echo and fast spin echo imaging demonstrated the feasibility of body imaging at 10.5T with the designed array. While comparable power efficiencies can be achieved using dipole antenna arrays with static shimming at 10.5T; increasing RF nonuniformities underscore the need for efficient, robust, and safe parallel transmission methods. Magn Reson Med 77:434-443, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Phased array feed design technology for Large Aperture Microwave Radiometer (LAMR) Earth observations

NASA Technical Reports Server (NTRS)

Schuman, H. K.

1992-01-01

An assessment of the potential and limitations of phased array antennas in space-based geophysical precision radiometry is described. Mathematical models exhibiting the dependence of system and scene temperatures and system sensitivity on phased array antenna parameters and components such as phase shifters and low noise amplifiers (LNA) are developed. Emphasis is given to minimum noise temperature designs wherein the LNA's are located at the array level, one per element or subarray. Two types of combiners are considered: array lenses (space feeds) and corporate networks. The result of a survey of suitable components and devices is described. The data obtained from that survey are used in conjunction with the mathematical models to yield an assessment of effective array antenna noise temperature for representative geostationary and low Earth orbit systems. Practical methods of calibrating a space-based, phased array radiometer are briefly addressed as well.

Communication architecture for large geostationary platforms

NASA Technical Reports Server (NTRS)

Bond, F. E.

1979-01-01

Large platforms have been proposed for supporting multipurpose communication payloads to exploit economy of scale, reduce congestion in the geostationary orbit, provide interconnectivity between diverse earth stations, and obtain significant frequency reuse with large multibeam antennas. This paper addresses a specific system design, starting with traffic projections in the next two decades and discussing tradeoffs and design approaches for major components including: antennas, transponders, and switches. Other issues explored are selection of frequency bands, modulation, multiple access, switching methods, and techniques for servicing areas with nonuniform traffic demands. Three-major services are considered: a high-volume trunking system, a direct-to-user system, and a broadcast system for video distribution and similar functions. Estimates of payload weight and d.c. power requirements are presented. Other subjects treated are: considerations of equipment layout for servicing by an orbit transfer vehicle, mechanical stability requirements for the large antennas, and reliability aspects of the large number of transponders employed.

Opto-mechanical design and gravity-deformation analysis on optical telescope in laser communication system

NASA Astrophysics Data System (ADS)

Fu, Sen; Du, Jindan; Song, Yiwei; Gao, Tianyu; Zhang, Daqing; Wang, Yongzhi

2017-11-01

In space laser communication, optical antennas are one of the main components and the precision of optical antennas is very high. In this paper, it is based on the R-C telescope and it is carried out that the design and simulation of optical lens and supporting truss, according to the parameters of the systems. And a finite element method (FEM) was used to analyze the deformation of the optical lens. Finally, the Zernike polynomial was introduced to fit the primary mirror with a diameter of 250mm. The objective of this study is to determine whether the wave-front aberration of the primary mirror can meet the imaging quality. The results show that the deterioration of the imaging quality caused by the gravity deformation of primary and secondary mirrors. At the same time, the optical deviation of optical antenna increase with the diameter of the pupil.

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.

Baseline antenna design for space exploration initiative

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

Simulation of Conformal Spiral Slot Antennas on Composite Platforms

NASA Technical Reports Server (NTRS)

Volakis, J. L.; Nurnberger, M. W.; Ozdemir,T.

1998-01-01

During the course of the grant, we wrote and distributed about 12 reports and an equal number of journal papers supported fully or in part by this grant. The list of reports (title & abstract) and papers are given in Appendices A and B. This grant has indeed been instrumental in developing a robust hybrid finite element method for the analysis of complex broadband antennas on doubly curved platforms. Previous to the grant, our capability was limited to simple printed patch antennas on mostly planar platforms. More specifically: (1) mixed element formulations were developed and new edge-based prisms were introduced; (2) these elements were important in permitting flexibility in geometry gridding for most antennas of interest; (3) new perfectly matched absorbers were introduced for mesh truncations associated with highly curved surfaces; (4) fast integral algorithms were introduced for boundary integral truncations reducing CPU time from O(N-2) down to O(N-1.5) or less; (5) frequency extrapolation schemes were developed for efficient broadband performance evaluations. This activity has been successfully continued by NASA researchers; (6) computer codes were developed and extensively tested for several broadband configurations. These include FEMA-CYL, FEMA-PRISM and FEMA-TETRA written by L. Kempel, T. Ozdemir and J. Gong, respectively; (7) a new infinite balun feed was designed nearly constant impedance over the 800-3000 MHz operational band; (8) a complete slot spiral antenna was developed, fabricated and tested at NASA Langley. This new design is a culmination of the projects goals and integrates the computational and experimental efforts. this antenna design resulted in a U.S. patent and was revised three times to achieve the desired bandwidth and gain requirements from 800-3000 MHz.

Testing of the BipiColombo Antenna Pointing Mechanism

NASA Astrophysics Data System (ADS)

Campo, Pablo; Barrio, Aingeru; Martin, Fernando

2015-09-01

BepiColombo is an ESA mission to Mercury, its planetary orbiter (MPO) has two antenna pointing mechanism, High gain antenna (HGA) pointing mechanism steers and points a large reflector which is integrated at system level by TAS-I Rome. Medium gain antenna (MGA) APM points a 1.5 m boom with a horn antenna. Both radiating elements are exposed to sun fluxes as high as 10 solar constants without protections.A previous paper [1] described the design and development process to solve the challenges of performing in harsh environment.. Current paper is focused on the testing process of the qualification units. Testing performance of antenna pointing mechanism in its specific environmental conditions has required special set-up and techniques. The process has provided valuable feedback on the design and the testing methods which have been included in the PFM design and tests.Some of the technologies and components were developed on dedicated items priort to EQM, but once integrated, test behaviour had relevant differences.Some of the major concerns for the APM testing are:- Create during the thermal vacuum testing the qualification temperature map with gradients along the APM. From of 200oC to 70oC.- Test in that conditions the radio frequency and pointing performances adding also high RF power to check the power handling and self-heating of the rotary joint.- Test in life up to 12000 equivalent APM revolutions, that is 14.3 million motor revolutions in different thermal conditions.- Measure low thermal distortion of the mechanical chain, being at the same time insulated from external environment and interfaces (55 arcsec pointing error)- Perform deployment of large items guaranteeing during the process low humidity, below 5% to protect dry lubrication- Verify stability with representative inertia of large boom or reflector 20 Kgm2.

MSAT-X phased array antenna adaptions to airborne applications

NASA Technical Reports Server (NTRS)

Sparks, C.; Chung, H. H.; Peng, S. Y.

1988-01-01

The Mobile Satellite Experiment (MSAT-X) phased array antenna is being modified to meet future requirements. The proposed system consists of two high gain antennas mounted on each side of a fuselage, and a low gain antenna mounted on top of the fuselage. Each antenna is an electronically steered phased array based on the design of the MSAT-X antenna. A beamforming network is connected to the array elements via coaxial cables. It is essential that the proposed antenna system be able to provide an adequate communication link over the required space coverage, which is 360 degrees in azimuth and from 20 degrees below the horizon to the zenith in elevation. Alternative design concepts are suggested. Both open loop and closed loop backup capabilities are discussed. Typical antenna performance data are also included.

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

SKALA, a log-periodic array antenna for the SKA-low instrument: design, simulations, tests and system considerations

NASA Astrophysics Data System (ADS)

de Lera Acedo, E.; Razavi-Ghods, N.; Troop, N.; Drought, N.; Faulkner, A. J.

2015-10-01

The very demanding requirements of the SKA-low instrument call for a challenging antenna design capable of delivering excellent performance in radiation patterns, impedance matching, polarization purity, cost, longevity, etc. This paper is devoted to the development (design and test of the first prototypes) of an active ultra-wideband antenna element for the low-frequency instrument of the SKA radio telescope. The antenna element and differential low noise amplifier described here were originally designed to cover the former SKA-low band (70-450 MHz) but it is now aimed to cover the re-defined SKA-low band (50-350 MHz) and furthermore the antenna is capable of performing up to 650 MHz with the current design. The design is focused on maximum sensitivity in a wide field of view (+/- 45° from zenith) and low cross-polarization ratios. Furthermore, the size and cost of the element has to be kept to a minimum as millions of these antennas will need to be deployed for the full SKA in very compact configurations. The primary focus of this paper is therefore to discuss various design implications for the SKA-low telescope.

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

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

Meena, M. L., E-mail: madan.meena.ece@gamil.com; Parmar, Girish, E-mail: girish-parmar2002@yahoo.com; Kumar, Mithilesh, E-mail: mith-kr@yahoo.com

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

An Estimation for Availability of Battery less LF Band RFID Tag to Identify Patients in Operation Room from Viewpoint of Engineering

NASA Astrophysics Data System (ADS)

Hosaka, Ryosuke

Nowadays, medical accidents increase in Japanese patient environment. Especially, misidentification of the patients occurred in operation room of higher level hospitals. It is considered that the great deals of accidents are due to mistakes by nurse. However, the accidents are prevented by management of patients. If a suitable patient identification system is developed, the accidents are prevented. In this study, new patient identification system using battery less LF band RFID(Radio Frequency Identification) is proposed. In the method, battery less RFID tag is attached to patient. In operation room, patient is identified before operation using the proposed system. However, identification distance of RFID is small. It is important that extension of the distance. In this study, antennas of RFID tag and sensor are designed. Two types of tag are proposed. One of them is set on wristband. An antenna for the tag is designed as a circular shape with 30mm in diameter. The other one is shaped like a necklace. The antenna is also designed 220mm, 240mm and 260mm in diameter. Using necklace type new antenna, sufficient identification distance for detection of the tag in the operation room is realized. The patient identification is realized using the proposed system

Throughput Measurement of a Dual-Band MIMO Rectangular Dielectric Resonator Antenna for LTE Applications

PubMed Central

Nasir, Jamal; Jamaluddin, Mohd. Haizal; Ahmad Khan, Aftab; Kamarudin, Muhammad Ramlee; Leow, Chee Yen; Owais, Owais

2017-01-01

An L-shaped dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for long term evolution (LTE) applications is proposed. The presented antenna can transmit and receive information independently using fundamental TE111 and higher order TE121 modes of the DRA. TE111 degenerate mode covers LTE band 2 (1.85–1.99 GHz), 3 (1.71–1.88 GHz), and 9 (1.7499–1.7849 GHz) at fr = 1.8 GHz whereas TE121 covers LTE band 7 (2.5–2.69 GHz) at fr = 2.6 GHz, respectively. An efficient design method has been used to reduce mutual coupling between ports by changing the effective permittivity values of DRA by introducing a cylindrical air-gap at an optimal position in the dielectric resonator. This air-gap along with matching strips at the corners of the dielectric resonator keeps the isolation at a value more than 17 dB at both the bands. The diversity performance has also been evaluated by calculating the envelope correlation coefficient, diversity gain, and mean effective gain of the proposed design. MIMO performance has been evaluated by measuring the throughput of the proposed MIMO antenna. Experimental results successfully validate the presented design methodology in this work. PMID:28098807

Throughput Measurement of a Dual-Band MIMO Rectangular Dielectric Resonator Antenna for LTE Applications.

PubMed

Nasir, Jamal; Jamaluddin, Mohd Haizal; Ahmad Khan, Aftab; Kamarudin, Muhammad Ramlee; Yen, Bruce Leow Chee; Owais, Owais

2017-01-13

An L-shaped dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for long term evolution (LTE) applications is proposed. The presented antenna can transmit and receive information independently using fundamental TE 111 and higher order TE 121 modes of the DRA. TE 111 degenerate mode covers LTE band 2 (1.85-1.99 GHz), 3 (1.71-1.88 GHz), and 9 (1.7499-1.7849 GHz) at f r = 1.8 GHz whereas TE 121 covers LTE band 7 (2.5-2.69 GHz) at f r = 2.6 GHz, respectively. An efficient design method has been used to reduce mutual coupling between ports by changing the effective permittivity values of DRA by introducing a cylindrical air-gap at an optimal position in the dielectric resonator. This air-gap along with matching strips at the corners of the dielectric resonator keeps the isolation at a value more than 17 dB at both the bands. The diversity performance has also been evaluated by calculating the envelope correlation coefficient, diversity gain, and mean effective gain of the proposed design. MIMO performance has been evaluated by measuring the throughput of the proposed MIMO antenna. Experimental results successfully validate the presented design methodology in this work.

A new radio propagation model at 2.4 GHz for wireless medical body sensors in outdoor environment.

PubMed

Yang, Daniel S

2013-01-01

This study investigates the effect of antenna height, receive antenna placement on human body, and distance between transmitter and receiver on the loss of wireless signal power in order to develop a wireless propagation model for wireless body sensors. Although many studies looked at the effect of distance, few studies were found that investigated methodically the effect of antenna height and antenna placement on the human body. Transmit antenna heights of 1, 2, and 3 meters, receive antenna heights of 1 and 1.65 meters, "on-body" and "off-body" placements of receive antenna, and a total of 11 distances ranging from 1 to 45 meters are tested in relation to received power in dBm. Multiple regression is used to analyze the data. Significance of a variable is tested by comparing its p-value with alpha, and model fit is assessed using adjusted R(2) and s of residuals. It is found that an increase in antenna height would increase power--but only for transmit antenna. The receive antenna height has a surprising, opposite effect in the on-body case and an insignificant effect in the off-body case. To formalize the propagation model, coefficient values from multiple regression are incorporated in an extension of the log-distance model to produce a new empirical model for on-body and off-body cases, and the new empirical model could conceivably be utilized to design more reliable wireless links for medical body sensors.

Procedures for the use of aircraft in wildlife biotelemetry studies

USGS Publications Warehouse

Gilmer, David S.; Cowardin, Lewis M.; Duval, Renee L.; Mechlin, Larry M.; Shaiffer, Charles W.; Kuechle, V.B.

1981-01-01

This is a report on the state of the art methodology and on questions that arise while one is preparing to use aircraft in a biotelemetry study. In general the first step in preparing to mount an antenna on an aircraft is to consult with a certified aircraft mechanic. Aircraft certification is discussed to provide background information concerning the role of the Federal Aviation Administration (FAA) in regulating the use of biotelemetry antennas on aircraft. However, approval of any specific design of antenna mount rests with local FAA authority. Airplane and helicopter antenna attachments are described. Performance of the receiving antenna system is discussed with emphasis on how variables as aircraft type and antenna configuration may influence reception. The side-looking vs. front-looking antenna configuration and the VHF vs. HF frequency band are generally recommended for most aerial tracking studies. Characteristics of receivers, transmitters, and antennas that might influence tracking are discussed. Specific topics such as calibration of receivers and transmitter quality control are considered. Suggestions in preparing for and conducting tracking flights that will improve overall efficiency and safety are presented. Search techniques, including procedures for conducting large and specific area surveys as well as methods to improve and evaluate search efficiency, are discussed. A concluding section considers special topics such as low-level operations and the use of helicopters. Diagrams of antenna mounts, equipment check-off lists, and antenna test procedures are included as appendices.

Evaluation of Bluetooth communications for the deployment of assisted living technologies in home environments.

PubMed

McGrath, Michael J; Burns, Adrian; Dishongh, Terry

2007-01-01

Using five different commercially available class one and class two Bluetooth dongles a total of seven homes which represented a cross section of typical Irish homes were surveyed to determine the effect of construction methods, house size, sensor placement, host placement, antenna design and RF interference had on the link quality of Bluetooth enabled sensors. The results obtained indicates there is high variability in the link quality which is determined by the quality of the BT radio, placement of the antenna on both the master and slave, the number of walls which must be penetrated and the construction materials used in the wall. The placement of the sensor was the single biggest factor in determining the link quality. The type of construction used in the interior walls has significant influence also. The final factor of significant influence was the type of antenna used on the Bluetooth dongle. The use of an external antenna gave significantly better range performance than an internal antenna.

Coplanar UHF RFID tag antenna with U-shaped inductively coupled feed for metallic applications.

PubMed

Salman, Karrar Naji; Ismail, Alyani; Raja Abdullah, Raja Syamsul Azmir; Saeedi, Tale

2017-01-01

In this paper, we present a novel compact, coplanar, tag antenna design for metallic objects. Electrically small antenna has designed for a UHF RFID (860-960 MHz) based on a proximity-coupled feed through. Furthermore, two symmetrical Via-loaded coplanar grounds fed by a U-shaped inductively coupled feed through an embedded transmission line. This configuration results in an antenna with dimensions of 31 × 19.5 × 3.065 mm3 at 915 MHz, and the total gain for the antenna is 0.12 dBi. The Via-loaded coplanar and U-shaped inductively coupled feeds allow the antenna to provide flexible tuning in terms of antenna impedance. In addition, a figure of merit is applied for the proposed tag antenna, and the results are presented. The read range is measured to be 4.2 m, which is very close to simulated values. This antenna measurement shows very good agreement with simulations.

A printed Yagi-Uda antenna for application in magnetic resonance thermometry guided microwave hyperthermia applicators

NASA Astrophysics Data System (ADS)

Paulides, M. M.; Mestrom, R. M. C.; Salim, G.; Adela, B. B.; Numan, W. C. M.; Drizdal, T.; Yeo, D. T. B.; Smolders, A. B.

2017-03-01

Biological studies and clinical trials show that addition of hyperthermia stimulates conventional cancer treatment modalities and significantly improves treatment outcome. This supra-additive stimulation can be optimized by adaptive hyperthermia to counteract strong and dynamic thermoregulation. The only clinically proven method for the 3D non-invasive temperature monitoring required is by magnetic resonance (MR) temperature imaging, but the currently available set of MR compatible hyperthermia applicators lack the degree of heat control required. In this work, we present the design and validation of a high-frequency (433 MHz ISM band) printed circuit board antenna with a very low MR-footprint. This design is ideally suited for use in a range of hyperthermia applicator configurations. Experiments emulating the clinical situation show excellent matching properties of the antenna over a 7.2% bandwidth (S 11  <  -15 dB). Its strongly directional radiation properties minimize inter-element coupling for typical array configurations (S 21  <  -23 dB). MR imaging distortion by the antenna was found negligible and MR temperature imaging in a homogeneous muscle phantom was highly correlated with gold-standard probe measurements (root mean square error: RMSE  =  0.51 °C and R 2  =  0.99). This work paves the way for tailored MR imaging guided hyperthermia devices ranging from single antenna or incoherent antenna-arrays, to real-time adaptive hyperthermia with phased-arrays.

47 CFR 74.735 - Power limitations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... designed antennas with no model number, or in the case of a composite antenna composed of two or more... full description of the design of the antenna should also be submitted. (2) Relative field horizontal...

47 CFR 74.735 - Power limitations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... designed antennas with no model number, or in the case of a composite antenna composed of two or more... full description of the design of the antenna should also be submitted. (2) Relative field horizontal...

47 CFR 74.735 - Power limitations.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... designed antennas with no model number, or in the case of a composite antenna composed of two or more... full description of the design of the antenna should also be submitted. (2) Relative field horizontal...

47 CFR 74.735 - Power limitations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... designed antennas with no model number, or in the case of a composite antenna composed of two or more... full description of the design of the antenna should also be submitted. (2) Relative field horizontal...

47 CFR 74.735 - Power limitations.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... designed antennas with no model number, or in the case of a composite antenna composed of two or more... full description of the design of the antenna should also be submitted. (2) Relative field horizontal...

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.

Design principles for wave plate metasurfaces using plasmonic L-shaped nanoantennas

NASA Astrophysics Data System (ADS)

Tahir, Asad A.; Schulz, Sebastian A.; De Leon, Israel; Boyd, Robert W.

2017-03-01

Plasmonic L-shaped antennas are an important building block of metasurfaces and have been used to fabricate ultra-thin wave plates. In this work we present principles that can be used to design wave plates at a wavelength of choice and for diverse application requirements using arrays of L-shaped plasmonic antennas. We derive these design principles by studying the behavior of the vast parameter space of these antenna arrays. We show that there are two distinct regimes: a weak inter-particle coupling and a strong inter-particle coupling regime. We describe the behavior of the antenna array in each regime with regards to wave plate functionality, without resorting to approximate theoretical models. Our work is the first to explain these design principles and serves as a guide for designing wave plates for specific application requirements using plasmonic L-shaped antenna arrays.

Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears.

PubMed

Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

2016-07-26

In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor.

Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears

PubMed Central

Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

2016-01-01

In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor. PMID:27472331

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.

Investigation of fluorine-doped tin oxide based optically transparent E-shaped patch antenna for terahertz communications

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

Anand, S., E-mail: anand.s.krishna@gmail.com, E-mail: darak.mayur@gmail.com, E-mail: srk@nitt.edu; Darak, Mayur Sudesh, E-mail: anand.s.krishna@gmail.com, E-mail: darak.mayur@gmail.com, E-mail: srk@nitt.edu; Kumar, D. Sriram, E-mail: anand.s.krishna@gmail.com, E-mail: darak.mayur@gmail.com, E-mail: srk@nitt.edu

2014-10-15

In this paper, a fluorine-doped tin oxide based optically transparent E-shaped patch antenna is designed and its radiation performance is analyzed in the 705 – 804 GHz band. As optically transparent antennas can be mounted on optical display, they facilitate the reduction of overall system size. The proposed antenna design is simulated using electromagnetic solver - Ansys HFSS and its characteristics such as impedance bandwidth, directivity, radiation efficiency and gain are observed. Results show that the fluorine-doped tin oxide based optically transparent patch antenna overcomes the conventional patch antenna limitations and thus the same can be used for solar cellmore » antenna used in satellite systems.« less

47 CFR 73.753 - Antenna systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 4 2014-10-01 2014-10-01 false Antenna systems. 73.753 Section 73.753... International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be designed and operated so that the radiated power in...

47 CFR 73.753 - Antenna systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 4 2013-10-01 2013-10-01 false Antenna systems. 73.753 Section 73.753... International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be designed and operated so that the radiated power in...

47 CFR 73.753 - Antenna systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 4 2012-10-01 2012-10-01 false Antenna systems. 73.753 Section 73.753... International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be designed and operated so that the radiated power in...

47 CFR 73.753 - Antenna systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 4 2011-10-01 2011-10-01 false Antenna systems. 73.753 Section 73.753... International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be designed and operated so that the radiated power in...

47 CFR 73.753 - Antenna systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 73.753 Section 73.753... International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be designed and operated so that the radiated power in...

Modeling and Control of the Redundant Parallel Adjustment Mechanism on a Deployable Antenna Panel

PubMed Central

Tian, Lili; Bao, Hong; Wang, Meng; Duan, Xuechao

2016-01-01

With the aim of developing multiple input and multiple output (MIMO) coupling systems with a redundant parallel adjustment mechanism on the deployable antenna panel, a structural control integrated design methodology is proposed in this paper. Firstly, the modal information from the finite element model of the structure of the antenna panel is extracted, and then the mathematical model is established with the Hamilton principle; Secondly, the discrete Linear Quadratic Regulator (LQR) controller is added to the model in order to control the actuators and adjust the shape of the panel. Finally, the engineering practicality of the modeling and control method based on finite element analysis simulation is verified. PMID:27706076

Compact self-grounded Bow-Tie antenna design for an UWB phased-array hyperthermia applicator.

PubMed

Takook, Pegah; Persson, Mikael; Gellermann, Johanna; Trefná, Hana Dobšíček

2017-01-08

Using UWB hyperthermia systems has the potential to improve the heat delivery to deep seated tumours. In this paper, we present a novel self-grounded Bow-Tie antenna design which is to serve as the basis element in a phased-array applicator. The UWB operation in the frequency range of 0.43-1 GHz is achieved by immersing the antenna in a water bolus. The radiation characteristics are improved by appropriate shaping the water bolus and by inclusion of dielectric layers on the top of the radiating arms of the antenna. In order to find the most appropriate design, we use a combination of performance indicators representing the most important attributes of the antenna. These are the UWB impedance matching, the transmission capability and the effective field size. The antenna was constructed and experimentally validated on muscle-like phantom. The measured reflection and transmission coefficients as well as radiation characteristics are in excellent agreement with the simulated results. MR image acquisitions with antenna located inside MR bore indicate a negligible distortion of the images by the antenna itself, which indicates MR compatibility.

The Application of the FDTD Method to Millimeter-Wave Filter Circuits Including the Design and Analysis of a Compact Coplanar

NASA Technical Reports Server (NTRS)

Oswald, J. E.; Siegel, P. H.

1994-01-01

The finite difference time domain (FDTD) method is applied to the analysis of microwave, millimeter-wave and submillimeter-wave filter circuits. In each case, the validity of this method is confirmed by comparison with measured data. In addition, the FDTD calculations are used to design a new ultra-thin coplanar-strip filter for feeding a THz planar-antenna mixer.

Reconfigurable Antennas for High Data Rate Multi-beam Communication Systems

NASA Technical Reports Server (NTRS)

Bernhard, Jennifer T.; Michielssen, Eric

2005-01-01

High-speed (2-100 Mb/sec) wireless data communication - whether land- or satellite-based - faces a major challenge: high error rates caused by interference and unpredictable environments. A planar antenna system that can be reconfigured to respond to changing conditions has the potential to dramatically improve data throughput and system reliability. Moreover, new planar antenna designs that reduce array size, weight, and cost can have a significant impact on terrestrial and satellite communication system performance. This research developed new individually-reconfigurable planar antenna array elements that can be adjusted to provide multiple beams while providing increased scan angles and higher aperture efficiency than traditional diffraction-limited arrays. These new elements are microstrip spiral antennas with specialized tuning mechanisms that provide adjustable radiation patterns. We anticipate that these new elements can be used in both large and small arrays for inter-satellite communication as well as tracking of multiple mobile surface-based units. Our work has developed both theoretical descriptions as well as experimental prototypes of the antennas in both single element and array embodiments. The technical summary of the results of this work is divided into six sections: A. Cavity model for analysis and design of pattern reconfigurable antennas; B. Performance of antenna in array configurations for broadside and endfire operation; C. Performance of antenna in array configurations for beam scanning operation; D. Simulation of antennas in infinite phased arrays; E. Demonstration of antenna with commercially-available RF MEMS switches; F. Design of antenna MEMS switch combinations for direct simultaneous fabrication.

Cable-catenary large antenna concept

NASA Technical Reports Server (NTRS)

Akle, W.

1985-01-01

Deployable to very large diameters (over 1000 ft), while still remaining compatible with a complete satellite system launch by STS, the cable-catenary antenna comprises: 8 radial deployable boom masts; a deployable hub and feed support center mast; balanced front and back, radial and circumferential catenary cabling for highly accurate (mm) surface control; no interfering cabling in the antenna field; and an RF reflecting mesh supported on the front catenaries. Illustrations show the antenna-satellite system deployed and stowed configurations; the antenna deployment sequence; the design analysis logic; the sizing analysis output, and typical parametric design data.

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.

An improved broadband E patch microstrip antenna for wireless communications

NASA Astrophysics Data System (ADS)

Bzeih, Amer; Chahine, Soubhi Abou; Kabalan, Karim Y.; El-Hajj, Ali; Chehab, Ali

2007-12-01

A broadband probe-fed microstrip antenna with E-shaped patch on a single-layer air substrate is investigated. Bandwidth enhancement of the antenna is achieved by inserting two parallel slots into its radiating patch. The effects of the antenna parameters are analyzed, and their optimal values for broadband operation are obtained. The design parameters are formulated as a function of the center frequency, and the empirical equations are validated by simulation. A 51.5% enhanced E patch antenna for modern wireless communications (Personal Communications Service, Digital Cellular System, Universal Mobile Telecommunications System, Wireless Local Area Network 802.11 b/g, and Bluetooth) is designed, simulated, fabricated, and measured. A comparison between simulated and measured results is presented, and it showed satisfactory agreement. Moreover, the effect of incorporating more parallel slots into the radiating patch is investigated. The antenna is designed and simulated for different scenarios (four slots, six slots, and eight slots), where a bandwidth of 57% is achieved in the eight-slot design.

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.

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.

47 CFR 73.53 - Requirements for authorization of antenna monitors.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 4 2014-10-01 2014-10-01 false Requirements for authorization of antenna... antenna monitors. (a) Antenna monitors shall be verified for compliance with the technical requirements in...) An antenna monitor shall meet the following specifications: (1) The monitor shall be designed to...

47 CFR 73.53 - Requirements for authorization of antenna monitors.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 4 2011-10-01 2011-10-01 false Requirements for authorization of antenna... antenna monitors. (a) Antenna monitors shall be verified for compliance with the technical requirements in...) An antenna monitor shall meet the following specifications: (1) The monitor shall be designed to...

47 CFR 73.53 - Requirements for authorization of antenna monitors.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 4 2012-10-01 2012-10-01 false Requirements for authorization of antenna... antenna monitors. (a) Antenna monitors shall be verified for compliance with the technical requirements in...) An antenna monitor shall meet the following specifications: (1) The monitor shall be designed to...

47 CFR 73.53 - Requirements for authorization of antenna monitors.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false Requirements for authorization of antenna... antenna monitors. (a) Antenna monitors shall be verified for compliance with the technical requirements in...) An antenna monitor shall meet the following specifications: (1) The monitor shall be designed to...

47 CFR 73.53 - Requirements for authorization of antenna monitors.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 4 2013-10-01 2013-10-01 false Requirements for authorization of antenna... antenna monitors. (a) Antenna monitors shall be verified for compliance with the technical requirements in...) An antenna monitor shall meet the following specifications: (1) The monitor shall be designed to...

The Parametric Study and Fine-Tuning of Bow-Tie Slot Antenna with Loaded Stub

PubMed Central

2017-01-01

A printed Bow-Tie slot antenna with loaded stub is proposed and the effects of changing the dimensions of the slot area, the stub and load sizes are considered in this paper. These parameters have a considerable effect on the antenna characteristics as well as its performance. An in-depth parametric study of these dimensions is presented. This paper proposes the necessary conditions for initial approximation of dimensions needed to design this antenna. In order to achieve the desired performance of the antenna fine tuning of all sizes of these parameters is required. The parametric studies used in this paper provide proper trends for initiation and tuning the design. A prototype of the antenna for 1.7GHz to 2.6GHz band is fabricated. Measurements conducted verify that the designed antenna has wideband characteristics with 50% bandwidth around the center frequency of 2.1GHz. Conducted measurements for reflection coefficient (S11) and radiation pattern also validate our simulation results. PMID:28114354

The Parametric Study and Fine-Tuning of Bow-Tie Slot Antenna with Loaded Stub.

PubMed

Shafiei, M M; Moghavvemi, Mahmoud; Wan Mahadi, Wan Nor Liza

2017-01-01

A printed Bow-Tie slot antenna with loaded stub is proposed and the effects of changing the dimensions of the slot area, the stub and load sizes are considered in this paper. These parameters have a considerable effect on the antenna characteristics as well as its performance. An in-depth parametric study of these dimensions is presented. This paper proposes the necessary conditions for initial approximation of dimensions needed to design this antenna. In order to achieve the desired performance of the antenna fine tuning of all sizes of these parameters is required. The parametric studies used in this paper provide proper trends for initiation and tuning the design. A prototype of the antenna for 1.7GHz to 2.6GHz band is fabricated. Measurements conducted verify that the designed antenna has wideband characteristics with 50% bandwidth around the center frequency of 2.1GHz. Conducted measurements for reflection coefficient (S11) and radiation pattern also validate our simulation results.

Microstrip antenna study for Pioneer Saturn/Uranus atmosphere entry probe

NASA Technical Reports Server (NTRS)

Kuhlman, E. A.

1974-01-01

The design parameters of a microstrip antenna were studied to determine its performance characteristics as affected by an atmospheric entry probe environment. The technical literature was reviewed to identify the known design and performance characteristics. These data were used to evaluate the expected effects of mission environments on the microstrip antenna design proposed for the Saturn/Uranus Atmospheric Entry Probe (SAEP). Radiation patterns and VSWR measurements were made to evaluate the performance in the SAEP thermal environment. Results of the literature search and pattern tests confirm that the microstrip antenna is a good choice as a transmitting antenna on the SAEP. The microstrip antenna is efficient, compact, and well suited to a space environment. The pattern can be controlled with a minimum beamwidth of 60 degrees (air substrate; e.g., honeycomb structure) and a maximum on the order of 100 degrees with higher dielectric constant substrates. The power handling capacity is good and can be improved by covering the antenna with a dielectric cover.

Analysis and Design of a Long Range PTFE Substrate UHF RFID Tag for Cargo Container Identification

NASA Astrophysics Data System (ADS)

Petrariu, Adrian-Ioan; Popa, Valentin

2016-01-01

In this paper, a high-performances microstrip antenna for UHF (ultra high frequency) RFID (radio frequency identification) tag is designed, prototyped and tested. The antenna consists of two main components: a 1.52 mm RT/duroid 5880 laminate substrate on which the antenna is designed and a 10 mm polytetrafluoroethylene (PTFE) dielectric material placed as a separator between the antenna and the reference ground plane for the microstrip antenna. With this structure, the RFID tag can reach a maximum reading distance of 19 m, although the antenna has a compact size of 80 mm × 50 mm. The long reading distance is obtained by attaching to the antenna an RFID chip that can provide a reading sensitivity of -20.5 dBm. The high bandwidth from 677 MHz to 947 MHz measured at -10 dB, makes the tag being usable worldwide especially for cargo container identification, the main purpose of this research.

Graphene-based Yagi-Uda antenna with reconfigurable radiation patterns

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

Wu, Yongle, E-mail: wuyongle138@gmail.com; Qu, Meijun; Jiao, Lingxiao

This paper presents a radiation pattern reconfigurable Yagi-Uda antenna based on graphene operating at terahertz frequencies. The antenna can be reconfigured to change the main beam pattern into two or four different radiation directions. The proposed antenna consists of a driven dipole radiation conductor, parasitic strips and embedded graphene. The hybrid graphene-metal implementation enables the antenna to have dynamic surface conductivity, which can be tuned by changing the chemical potentials. Therefore, the main beam direction, the resonance frequency, and the front-to-back ratio of the proposed antenna can be controlled by tuning the chemical potentials of the graphene embedded in differentmore » positions. The proposed two-beam reconfigurable Yagi-Uda antenna can achieve excellent unidirectional symmetrical radiation pattern with the front-to-back ratio of 11.9 dB and the10-dB impedance bandwidth of 15%. The different radiation directivity of the two-beam reconfigurable antenna can be achieved by controlling the chemical potentials of the graphene embedded in the parasitic stubs. The achievable peak gain of the proposed two-beam reconfigurable antenna is about 7.8 dB. Furthermore, we propose a four-beam reconfigurable Yagi-Uda antenna, which has stable reflection-coefficient performance although four main beams in reconfigurable cases point to four totally different directions. The corresponding peak gain, front-to-back ratio, and 10-dB impedance bandwidth of the four-beam reconfigurable antenna are about 6.4 dB, 12 dB, and 10%, respectively. Therefore, this novel design method of reconfigurable antennas is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems.« less

Wearable Inset-Fed FR4 Microstrip Patch Antenna Design

NASA Astrophysics Data System (ADS)

Zaini, S. R. Mohd; Rani, K. N. Abdul

2018-03-01

This project proposes the design of a wireless body area network (WBAN) microstrip patch antenna covered by the jeans fabric as the outer layer operating at the center frequency, fc of 2.40 GHz. Precisely, the microstrip patch antenna with the inset-fed edge technique is designed and simulated systematically by using the Keysight Advanced Design System (ADS) software where the FR4 board with the dielectric constant, ɛr of 4.70, dissipation factor or loss tangent, tan δ of 0.02 and height, h of 1.60 mm is the chosen dielectric substrate. The wearable microstrip patch antenna design is then fabricated using the FR4 printed circuit board (PCB) material, hidden inside the jeans fabric, and attached to clothing, such as a jacket accordingly. Simulation and fabrication measurement results show that the designed microstrip patch antenna characteristics can be applied significantly within the industrial, scientific, and medical (ISM) radio band, which is at fc = 2.40 GHz.

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.

Frequency Modulation and Absorption Improvement of THz Micro-bolometer with Micro-bridge Structure by Spiral-Type Antennas

NASA Astrophysics Data System (ADS)

Gou, Jun; Niu, Qingchen; Liang, Kai; Wang, Jun; Jiang, Yadong

2018-03-01

Antenna-coupled micro-bridge structure is proven to be a good solution to extend infrared micro-bolometer technology for THz application. Spiral-type antennas are proposed in 25 μm × 25 μm micro-bridge structure with a single separate linear antenna, two separate linear antennas, or two connected linear antennas on the bridge legs, in addition to traditional spiral-type antenna on the support layer. The effects of structural parameters of each antenna on THz absorption of micro-bridge structure are discussed for optimized absorption of 2.52 THz wave radiated by far infrared CO2 lasers. The design of spiral-type antenna with two separate linear antennas for wide absorption peak and spiral-type antenna with two connected linear antennas for relatively stable absorption are good candidates for high absorption at low absorption frequency with a rotation angle of 360* n ( n = 1.6). Spiral-type antenna with extended legs also provides a highly integrated micro-bridge structure with fast response and a highly compatible, process-simplified way to realize the structure. This research demonstrates the design of several spiral-type antenna-coupled micro-bridge structures and provides preferred schemes for potential device applications in room temperature sensing and real-time imaging.

Frequency Modulation and Absorption Improvement of THz Micro-bolometer with Micro-bridge Structure by Spiral-Type Antennas.

PubMed

Gou, Jun; Niu, Qingchen; Liang, Kai; Wang, Jun; Jiang, Yadong

2018-03-05

Antenna-coupled micro-bridge structure is proven to be a good solution to extend infrared micro-bolometer technology for THz application. Spiral-type antennas are proposed in 25 μm × 25 μm micro-bridge structure with a single separate linear antenna, two separate linear antennas, or two connected linear antennas on the bridge legs, in addition to traditional spiral-type antenna on the support layer. The effects of structural parameters of each antenna on THz absorption of micro-bridge structure are discussed for optimized absorption of 2.52 THz wave radiated by far infrared CO 2 lasers. The design of spiral-type antenna with two separate linear antennas for wide absorption peak and spiral-type antenna with two connected linear antennas for relatively stable absorption are good candidates for high absorption at low absorption frequency with a rotation angle of 360*n (n = 1.6). Spiral-type antenna with extended legs also provides a highly integrated micro-bridge structure with fast response and a highly compatible, process-simplified way to realize the structure. This research demonstrates the design of several spiral-type antenna-coupled micro-bridge structures and provides preferred schemes for potential device applications in room temperature sensing and real-time imaging.

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...

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...

47 CFR 15.203 - Antenna requirement.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 1 2011-10-01 2011-10-01 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...

47 CFR 15.203 - Antenna requirement.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 1 2013-10-01 2013-10-01 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...

47 CFR 15.203 - Antenna requirement.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 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...

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

PubMed Central

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

2017-01-01

It is well known that multipath effect remains a dominant error source that affects the positioning accuracy of Global Navigation Satellite System (GNSS) receivers. Significant efforts have been made by researchers and receiver manufacturers to mitigate multipath error in the past decades. Recently, a multipath mitigation technique using dual-polarization antennas has become a research hotspot for it provides another degree of freedom to distinguish the line-of-sight (LOS) signal from the LOS and multipath composite signal without extensively increasing the complexity of the receiver. Numbers of multipath mitigation techniques using dual-polarization antennas have been proposed and all of them report performance improvement over the single-polarization methods. However, due to the unpredictability of multipath, multipath mitigation techniques based on dual-polarization are not always effective while few studies discuss the condition under which the multipath mitigation using a dual-polarization antenna can outperform that using a single-polarization antenna, which is a fundamental question for dual-polarization multipath mitigation (DPMM) and the design of multipath mitigation algorithms. In this paper we analyze the characteristics of the signal received by a dual-polarization antenna and use the maximum likelihood estimation (MLE) to assess the theoretical performance of DPMM in different received signal cases. Based on the assessment we answer this fundamental question and find the dual-polarization antenna’s capability in mitigating short delay multipath—the most challenging one among all types of multipath for the majority of the multipath mitigation techniques. Considering these effective conditions, we propose a dual-polarization sequential iterative maximum likelihood estimation (DP-SIMLE) algorithm for DPMM. The simulation results verify our theory and show superior performance of the proposed DP-SIMLE algorithm over the traditional one using only an RHCP antenna. PMID:28208832

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.

A new state space model for the NASA/JPL 70-meter antenna servo controls

NASA Technical Reports Server (NTRS)

Hill, R. E.

1987-01-01

A control axis referenced model of the NASA/JPL 70-m antenna structure is combined with the dynamic equations of servo components to produce a comprehansive state variable (matrix) model of the coupled system. An interactive Fortran program for generating the linear system model and computing its salient parameters is described. Results are produced in a state variable, block diagram, and in factored transfer function forms to facilitate design and analysis by classical as well as modern control methods.

Mechanically Reconfigurable Single-Arm Spiral Antenna Array for Generation of Broadband Circularly Polarized Orbital Angular Momentum Vortex Waves.

PubMed

Li, Long; Zhou, Xiaoxiao

2018-03-23

In this paper, a mechanically reconfigurable circular array with single-arm spiral antennas (SASAs) is designed, fabricated, and experimentally demonstrated to generate broadband circularly polarized orbital angular momentum (OAM) vortex waves in radio frequency domain. With the symmetrical and broadband properties of single-arm spiral antennas, the vortex waves with different OAM modes can be mechanically reconfigurable generated in a wide band from 3.4 GHz to 4.7 GHz. The prototype of the circular array is proposed, conducted, and fabricated to validate the theoretical analysis. The simulated and experimental results verify that different OAM modes can be effectively generated by rotating the spiral arms of single-arm spiral antennas with corresponding degrees, which greatly simplify the feeding network. The proposed method paves a reconfigurable way to generate multiple OAM vortex waves with spin angular momentum (SAM) in radio and microwave satellite communication applications.

Feasibility study for future implantable neural-silicon interface devices.

PubMed

Al-Armaghany, Allann; Yu, Bo; Mak, Terrence; Tong, Kin-Fai; Sun, Yihe

2011-01-01

The emerging neural-silicon interface devices bridge nerve systems with artificial systems and play a key role in neuro-prostheses and neuro-rehabilitation applications. Integrating neural signal collection, processing and transmission on a single device will make clinical applications more practical and feasible. This paper focuses on the wireless antenna part and real-time neural signal analysis part of implantable brain-machine interface (BMI) devices. We propose to use millimeter-wave for wireless connections between different areas of a brain. Various antenna, including microstrip patch, monopole antenna and substrate integrated waveguide antenna are considered for the intra-cortical proximity communication. A Hebbian eigenfilter based method is proposed for multi-channel neuronal spike sorting. Folding and parallel design techniques are employed to explore various structures and make a trade-off between area and power consumption. Field programmable logic arrays (FPGAs) are used to evaluate various structures.

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

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.

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.

Ultra-high-frequency microwave response from flexible transparent Au electromagnetic metamaterial nanopatterned antenna.

PubMed

Liu, Dingxin; Niu, Jiebin; Zhu, Haolin; Zhang, Jianyong

2018-02-09

Flexible transparent materials are a hot spot in current research but also a key technical difficulty in industry. They are playing an increasingly important role in flexible transparent display applications such as organic light-emitting diodes, transparent electrodes, and so on. On the other hand, the present research on nanopatterned antennas is mainly concentrated on the optical frequency but rarely on the microwave (such as 3G, 4G, and 5G) and terahertz frequency band communications, where nanopatterned antennas can have many novel applications. To the authors' knowledge, this is the first paper that presents a method for preparing a flexible transparent Au electromagnetic metamaterial nanopatterned antenna. We study its free-space performance at ultra-high frequency and its application in electronic products such as smartphones, tablets, personal computers, and wearable devices (such as smart watches) which have the function of mobile communication. The experimental results showed that the transparency of the antenna designed and fabricated in this work can be as high as 94%, and its efficiency can reach 74.5%-91.9% of antennas commonly seen at present in academia and industry. By adjusting the capacitive and inductive reactance of the nanopatterned antenna's matching circuit, combined with its measured efficiency and 3D electromagnetic simulation results, we speculate on the mechanism of the Au electromagnetic metamaterial nanopatterned antenna with good performance.

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.

Comparative analysis of on-orbit dynamic performance of several large antenna concepts

NASA Technical Reports Server (NTRS)

Andersen, G. C.; Garrett, L. B.; Calleson, R. E.

1985-01-01

A comparative analysis of the on-orbit dynamic performance of four large anetanna concepts is presented. Among the antenna concepts evaluated are: the box truss; tetrahedral truss; warp-radial rib; and the hoop and column antenna designs. The characteristics and magnitudes of the antennas' dynamic response were evaluated in terms of structural displacements and member loads incurred during various slew-rate maneuvers. The results of the dynamic response analysis are compared to the design requirements of the Land Mobile Satellite System (LMSS) with respect to surface accuracy, decenter, defocus, and angular rocking. Comments are made on the effectiveness of structural damping and the application of active controls for vibrational response reduction. Schematic illustrations of the antenna design concepts are provided.

Four-to-one power combiner for 20 GHz phased array antenna using RADC MMIC phase shifters

NASA Technical Reports Server (NTRS)

1991-01-01

The design and microwave simulation of two-to-one microstrip power combiners is described. The power combiners were designed for use in a four element phase array receive antenna subarray at 20 GHz. Four test circuits are described which were designed to enable testing of the power combiner and the four element phased array antenna. Test Circuit 1 enables measurement of the two-to-one power combiner. Test Circuit 2 enables measurement of the four-to-one power combiner. Test Circuit 3 enables measurement of a four element antenna array without phase shifting MMIC's in order to characterize the power combiner with the antenna patch-to-microstrip coaxial feedthroughs. Test circuit 4 is the four element phased array antenna including the RADC MMIC phase shifters and appropriate interconnects to provide bias voltages and control phase bits.

Concepts and cost trade-offs for land vehicle antennas in satellite mobile communications

NASA Technical Reports Server (NTRS)

Haddad, H. A.

1948-01-01

Several antenna design concepts, operating at UHF (821 to 825 MHz transmit and 866 to 870 MHz receive bands), with gain ranging between 6 and 12 dBic, that are suitable for land mobile vehicles are presented. The antennas may be used within CONUS and ALASKA to communicate to and from a geosynchronous satellite. Depending on the type of steering mechanism, the antennas are broken down into three categories; (1) electronically scanned arrays with phase shifters, (2) electronically switched arrays with switchable power dividers/combiners, and (3) mechanically steered arrays. The operating characteristics of two of these design concepts, one a conformal antenna with electronic beam steering and the other a nonconformal design with mechanical steering, were evaluated with regard to two and three satellite system. Cost estimates of various antenna concepts were made and plotted against their overall gain performance.

S-band omnidirectional antenna for the SERT-C satellite

NASA Technical Reports Server (NTRS)

Bassett, H. L.; Cofer, J. W., Jr.; Sheppard, R. R.; Sinclair, M. J.

1975-01-01

The program to design an S-band omnidirectional antenna system for the SERT-C spacecraft is discussed. The program involved the tasks of antenna analyses by computer techniques, scale model radiation pattern measurements of a number of antenna systems, full-scale RF measurements, and the recommended design, including detailed drawings. A number of antenna elements were considered: the cavity-backed spiral, quadrifilar helix, and crossed-dipoles were chosen for in-depth studies. The final design consisted of a two-element array of cavity-backed spirals mounted on opposite sides of spacecraft and fed in-phase through a hybrid junction. This antenna system meets the coverage requirement of having a gain of at least minus 10 dBi over 50 percent of a 4 pi steradian sphere with the solar panels in operation. This coverage level is increased if the ground station has the capability to change polarization.

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

NASA Astrophysics Data System (ADS)

Valjibhai, Gohil Jayesh; Bhatia, Deepak

2013-01-01

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

Printed wide-slot antenna design with bandwidth and gain enhancement on low-cost substrate.

PubMed

Samsuzzaman, M; Islam, M T; Mandeep, J S; Misran, N

2014-01-01

This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS.

Printed Wide-Slot Antenna Design with Bandwidth and Gain Enhancement on Low-Cost Substrate

PubMed Central

Samsuzzaman, M.; Islam, M. T.; Mandeep, J. S.; Misran, N.

2014-01-01

This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS. PMID:24696661

Three Dimensional (3 D) Printed Sierpinski Patch Antenna

DTIC Science & Technology

2017-10-25

of an equilateral triangle that is divided into smaller equilateral triangles. When this design is used in antenna theory, the antenna is compared to...REPORT ARE NOT TO BE CONSTRUED AS AN OFFICIAL DEPARTMENT OF THE ARMY POSITION UNLESS SO DESIGNATED BY OTHER AUTHORIZED DOCUMENTS. TRADE...distribution is unlimited. 12b. DISTRIBUTION CODE A 13. ABSTRACT (Maximum 200 Words) This report details the design , simulation, print, and

A module concept for a cable-mesh deployable antenna

NASA Technical Reports Server (NTRS)

Meguro, Akira

1993-01-01

This paper describes the design, manufacture, and deployment tests of a modular mesh deployable antenna. Reaction forces and moments created by a mesh and cable network are estimated using CASA. Deployment analysis is carried out using DADS. Three types of deployable antenna modules are developed and fabricated. Their design approach and deployment characteristics are also presented. Ground deployment tests are performed to verify design criteria.

The hydrogen epoch of reionization array dish III: measuring chromaticity of prototype element with reflectometry

NASA Astrophysics Data System (ADS)

Patra, Nipanjana; Parsons, Aaron R.; DeBoer, David R.; Thyagarajan, Nithyanandan; Ewall-Wice, Aaron; Hsyu, Gilbert; Leung, Tsz Kuk; Day, Cherie K.; de Lera Acedo, Eloy; Aguirre, James E.; Alexander, Paul; Ali, Zaki S.; Beardsley, Adam P.; Bowman, Judd D.; Bradley, Richard F.; Carilli, Chris L.; Cheng, Carina; Dillon, Joshua S.; Fadana, Gcobisa; Fagnoni, Nicolas; Fritz, Randall; Furlanetto, Steve R.; Glendenning, Brian; Greig, Bradley; Grobbelaar, Jasper; Hazelton, Bryna J.; Jacobs, Daniel C.; Julius, Austin; Kariseb, MacCalvin; Kohn, Saul A.; Lebedeva, Anna; Lekalake, Telalo; Liu, Adrian; Loots, Anita; MacMahon, David; Malan, Lourence; Malgas, Cresshim; Maree, Matthys; Martinot, Zachary; Mathison, Nathan; Matsetela, Eunice; Mesinger, Andrei; Morales, Miguel F.; Neben, Abraham R.; Pieterse, Samantha; Pober, Jonathan C.; Razavi-Ghods, Nima; Ringuette, Jon; Robnett, James; Rosie, Kathryn; Sell, Raddwine; Smith, Craig; Syce, Angelo; Tegmark, Max; Williams, Peter K. G.; Zheng, Haoxuan

2018-04-01

Spectral structures due to the instrument response is the current limiting factor for the experiments attempting to detect the redshifted 21 cm signal from the Epoch of Reionization (EoR). Recent advances in the delay spectrum methodology for measuring the redshifted 21 cm EoR power spectrum brought new attention to the impact of an antenna's frequency response on the viability of making this challenging measurement. The delay spectrum methodology provides a somewhat straightforward relationship between the time-domain response of an instrument that can be directly measured and the power spectrum modes accessible to a 21 cm EoR experiment. In this paper, we derive the explicit relationship between antenna reflection coefficient ( S 11) measurements made by a Vector Network Analyzer (VNA) and the extent of additional foreground contaminations in delay space. In the light of this mathematical framework, we examine the chromaticity of a prototype antenna element that will constitute the Hydrogen Epoch of Reionization Array (HERA) between 100 and 200 MHz. These reflectometry measurements exhibit additional structures relative to electromagnetic simulations, but we find that even without any further design improvement, such an antenna element will support measuring spatial k modes with line-of-sight components of k ∥ > 0.2 h Mpc- 1. We also find that when combined with the powerful inverse covariance weighting method used in optimal quadratic estimation of redshifted 21 cm power spectra the HERA prototype elements can successfully measure the power spectrum at spatial modes as low as k ∥ > 0.1 h Mpc- 1. This work represents a major step toward understanding the HERA antenna element and highlights a straightforward method for characterizing instrument response for future experiments designed to detect the 21 cm EoR power spectrum.

Coplanar UHF RFID tag antenna with U-shaped inductively coupled feed for metallic applications

PubMed Central

Ismail, Alyani; Raja Abdullah, Raja Syamsul Azmir; Saeedi, Tale

2017-01-01

In this paper, we present a novel compact, coplanar, tag antenna design for metallic objects. Electrically small antenna has designed for a UHF RFID (860–960 MHz) based on a proximity-coupled feed through. Furthermore, two symmetrical Via-loaded coplanar grounds fed by a U-shaped inductively coupled feed through an embedded transmission line. This configuration results in an antenna with dimensions of 31 × 19.5 × 3.065 mm3 at 915 MHz, and the total gain for the antenna is 0.12 dBi. The Via-loaded coplanar and U-shaped inductively coupled feeds allow the antenna to provide flexible tuning in terms of antenna impedance. In addition, a figure of merit is applied for the proposed tag antenna, and the results are presented. The read range is measured to be 4.2 m, which is very close to simulated values. This antenna measurement shows very good agreement with simulations. PMID:28570706

Design of Miniaturized Dual-Band Microstrip Antenna for WLAN Application

PubMed Central

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

2016-01-01

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

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

PubMed

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

2016-06-27

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

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

Effects of atmospheric turbulence on microwave and millimeter wave satellite communications systems. [attenuation statistics and antenna design

NASA Technical Reports Server (NTRS)

Devasirvatham, D. M. J.; Hodge, D. B.

1981-01-01

A model of the microwave and millimeter wave link in the presence of atmospheric turbulence is presented with emphasis on satellite communications systems. The analysis is based on standard methods of statistical theory. The results are directly usable by the design engineer.

Refractive and relativistic effects on ITER low field side reflectometer design.

PubMed

Wang, G; Rhodes, T L; Peebles, W A; Harvey, R W; Budny, R V

2010-10-01

The ITER low field side reflectometer faces some unique design challenges, among which are included the effect of relativistic electron temperatures and refraction of probing waves. This paper utilizes GENRAY, a 3D ray tracing code, to investigate these effects. Using a simulated ITER operating scenario, characteristics of the reflected millimeter waves after return to the launch plane are quantified as a function of a range of design parameters, including antenna height, antenna diameter, and antenna radial position. Results for edge/SOL measurement with both O- and X-mode polarizations using proposed antennas are reported.

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.

Dual S and Ku-band tracking feed for a TDRS reflector antenna

NASA Technical Reports Server (NTRS)

Pullara, J. C.; Bales, C. W.; Kefalas, G. P.; Uyehara, M.

1974-01-01

The results are presented of a trade study designed to identify a synchronous satellite antenna system suitable for receiving and transmitting data from lower orbiting satellites at both S- and K sub u-bands simultaneously as part of the Tracking and Data Relay Satellite System. All related problems associated with maintaining a data link between two satellites with a K sub u-band half-power beamwidth of 0.4 db are considered including data link maintenance techniques, beam pointing accuracies, gimbal and servo errors, solar heating, angle tracking schemes, acquisition problems and aids, tracking accuracies versus SNR, antenna feed designs, equipment designs, weight and power budgets, and detailed candidate antenna system designs.

An antenna-pointing mechanism for the ETS-6 K-band Single Access (KSA) antenna

NASA Technical Reports Server (NTRS)

Takada, Noboru; Amano, Takahiro; Ohhashi, Toshiro; Wachi, Shigeo

1991-01-01

Both the design philosophy for the Antenna Pointing Mechanism (APM) to be used for the K-band Single Access (KSA) antenna system and experimental results of the APM Engineering Model (EM) tests are described. The KSA antenna system will be flown on the Engineering Test Satellite 6 (ETS-6).

Comparative Study of Antenna Elements for TDRSS Enhanced Multiple Access System

NASA Technical Reports Server (NTRS)

Kory, Carol L.; Lambert, Kevin; Acosta, Roberto; Nessel, James

2006-01-01

We compare three antennas, which are candidates for the TDRSS-Continuation enhanced MA array antenna elements. Measured and simulated data show very good agreement for all antenna elements. All of the antennas meet the specifications with the exception of the SBA isolation. However, improvements can likely be made with further design efforts.

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.

Design, Fabrication and Testing of Two Dimensional Radio-Frequency Metamaterials

DTIC Science & Technology

2014-03-03

metasurfaces . These antennas are either MTM based or utilize MTMs to increase performance. The benefits of these antennas are: reduced size, lower...reduced size and increased quality factor. Finally, the antennas loaded with metasurfaces are similar to the MTM loading; in the fact that the... metasurface enhances the antenna performance instead of performing the antenna function. This type of antenna has shown increased directionality and

Design of compact electromagnetic impulse radiating antenna for melanoma treatment.

PubMed

Arockiasamy, Petrishia; Mohan, Sasikala

2016-01-01

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

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

NASA Technical Reports Server (NTRS)

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

2014-01-01

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

Embedded Meta-Material Antennas

DTIC Science & Technology

2009-01-31

influence of the overall capacitance . Based on the tunable SRRs, we designed a tunable loop antenna with SRRs and HPTs as tuning elements. In this case, we...are those of the authors) and should not be construed as an official Department of the Army position, policy or decision, unless so designated by...single aperture, which can provide significant miniaturization and flexibility to the entire system. To design such miniaturized antennas, new materials

Optimal sensor placement for deployable antenna module health monitoring in SSPS using genetic algorithm

NASA Astrophysics Data System (ADS)

Yang, Chen; Zhang, Xuepan; Huang, Xiaoqi; Cheng, ZhengAi; Zhang, Xinghua; Hou, Xinbin

2017-11-01

The concept of space solar power satellite (SSPS) is an advanced system for collecting solar energy in space and transmitting it wirelessly to earth. However, due to the long service life, in-orbit damage may occur in the structural system of SSPS. Therefore, sensor placement layouts for structural health monitoring should be firstly considered in this concept. In this paper, based on genetic algorithm, an optimal sensor placement method for deployable antenna module health monitoring in SSPS is proposed. According to the characteristics of the deployable antenna module, the designs of sensor placement are listed. Furthermore, based on effective independence method and effective interval index, a combined fitness function is defined to maximize linear independence in targeted modes while simultaneously avoiding redundant information at nearby positions. In addition, by considering the reliability of sensors located at deployable mechanisms, another fitness function is constituted. Moreover, the solution process of optimal sensor placement by using genetic algorithm is clearly demonstrated. At last, a numerical example about the sensor placement layout in a deployable antenna module of SSPS is presented, which by synthetically considering all the above mentioned performances. All results can illustrate the effectiveness and feasibility of the proposed sensor placement method in SSPS.

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...

Reduced-size spiral antenna design using dielectric overlay loading for use in ground penetrating radar and design of alternative antennas using Vivaldi radiators

NASA Astrophysics Data System (ADS)

Paolino, Donald D.; Neel, Michael M.; Franck, Charmaine C.

2002-08-01

Spiral antennas are one of the common radiators used in ground penetrating radar (GPR). Mine detection is generally performed in a frequency band of interest between 500 MHz to 4 GHz. This paper discusses technical recommendations and R&D performed by Naval Air Warfare Center (NAWC), China Lake, CA , resulting in our best effort spiral design emphasizing highest low band gain while maintaining overall axial ratio purity. This design consisted of a spiral printed on a high dielectric substrate that allowed the antenna to be used at lower frequencies then conventional plastic substrate based two arm spirals of the same diameter. A graded dielectric overlay scheme was employed to facilitate matching to free space on one side, and absorber lined cavity on the other. Test data is given in terms of match and free space patterns using spin linear sources to obtain antenna axial ratios. The low-end gain was improved from -17 dBi to -5 dBi. Two Vivaldi slot antennas (star junction fed and an antipodal construction) are discussed as alternative antennas offering broadband high gain and economical construction. Both designs produced good patterns with a +5 dBi average gain over the band. Patterns for the log spiral and Archimedean spiral, together with recommendations for future improvements are provided.

Simulation-based analysis of performance parameters of microstrip antennas with criss-cross metamaterial-based artificial substrate

NASA Astrophysics Data System (ADS)

Inamdar, Kirti; Kosta, Y. P.; Patnaik, S.

2014-10-01

In this paper, we present the design of a metamaterial-based microstrip patch antenna, optimized for bandwidth and multiple frequency operations. A criss-cross structure has been proposed, this shape has been inspired from the famous Jerusalem cross. The theory and design formulas to calculate various parameters of the proposed antenna have been presented. Design starts with the analysis of the proposed unit cell structure, and validating the response using software- HFSS Version 13, to obtain negative response of ε and μ- metamaterial. Following this, a metamaterial-based-microstrip-patch-antenna is designed. A detailed comparative study is conducted exploring the response of the designed patch made of metamaterial and that of the conventional patch. Finally, antenna parameters such as gain, bandwidth, radiation pattern, and multiple frequency responses are investigated and optimised for the same and present in table and response graphs. It is also observed that the physical dimension of the metamaterial-based patch antenna is smaller compared to its conventional counterpart operating at the same fundamental frequency. The challenging part was to develop metamaterial based on some signature structures and techniques that would offer advantage in terms of BW and multiple frequency operation, which is demonstrated in this paper. The unique shape proposed in this paper gives improvement in bandwidth without reducing the gain of the antenna.

Design and Test of Magnetic Wall Decoupling for Dipole Transmit/Receive Array for MR Imaging at the Ultrahigh Field of 7T.

PubMed

Yan, Xinqiang; Zhang, Xiaoliang; Wei, Long; Xue, Rong

2015-01-01

Radio-frequency coil arrays using dipole antenna technique have been recently applied for ultrahigh field magnetic resonance (MR) imaging to obtain the better signal-noise-ratio (SNR) gain at the deep area of human tissues. However, the unique structure of dipole antennas makes it challenging to achieve sufficient electromagnetic decoupling among the dipole antenna elements. Currently, there is no decoupling methods proposed for dipole antenna arrays in MR imaging. The recently developed magnetic wall (MW) or induced current elimination decoupling technique has demonstrated its feasibility and robustness in designing microstrip transmission line arrays, L/C loop arrays and monopole arrays. In this study, we aim to investigate the possibility and performance of MW decoupling technique in dipole arrays for MR imaging at the ultrahigh field of 7T. To achieve this goal, a two-channel MW decoupled dipole array was designed, constructed and analyzed experimentally through bench test and MR imaging. Electromagnetic isolation between the two dipole elements was improved from about -3.6 dB (without any decoupling treatments) to -16.5 dB by using the MW decoupling method. MR images acquired from a water phantom using the MW decoupled dipole array and the geometry factor maps were measured, calculated and compared with those acquired using the dipole array without decoupling treatments. The MW decoupled dipole array demonstrated well-defined image profiles from each element and had better geometry factor over the array without decoupling treatments. The experimental results indicate that the MW decoupling technique might be a promising solution to reducing the electromagnetic coupling of dipole arrays in ultrahigh field MRI, consequently improving their performance in SNR and parallel imaging.

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.

Frequency-reconfigurable water antenna of circular polarization

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

Zou, Meng; Pan, Jin; Shen, Zhongxiang, E-mail: ezxshen@ntu.edu.sg

A circularly polarized frequency-reconfigurable water antenna with high radiation efficiency is proposed based on the design concept of combining a frequency-reconfigurable radiating structure with a frequency-independent feeding structure. In this letter, a resonator made of distilled water and an Archimedean spiral slot are employed as the radiating and feeding structures, respectively. The operating frequency of the antenna can be continuously tuned over a very wide range while maintaining good impendence matching and circular polarization by changing the dimensions of the water resonator. A prototype antenna is designed, fabricated, and measured. Simulated and measured results demonstrate that the designed antenna exhibitsmore » a wide tuning frequency range from 155 MHz to 400 MHz with an average radiation efficiency of about 90% and good circular polarization.« less

A Wire Antenna Designed for Space Wave Radiation Over the Earth Using a Genetic Algorithm

DTIC Science & Technology

1997-12-01

are extended beyond that of connecting the wires in series. 1.6 Assumptions 1.6.1 Smooth Earth. It was not prudent for the research to account for an...and circuit grounds are connected in some manner. 1.7 Scope The research proposes a system antenna design, taking into account the link budget. The...1.10 Goals The purpose of the research is to conduct a thorough design approach taking into account all aspects of antenna design, to include the

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.

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.

Study of Dual Band Wearable Antennas Using Commonly Worn Fabric Materials

NASA Astrophysics Data System (ADS)

Das, Dipen Kumar

In recent years, body-centric communication has become one of the most attractive fields of study. The versatile applications of body-centric communication not only being used for health monitoring, but also for real-time communication purposes in special occupations. They are important for supporting a population with increasing life expectancy and increase the probability of survival for the people suffering from chronic illness. For both wearable and implantable form of body-centric communication, characterizing the system electromagnetically is very important. Given the constraints in power, size, weight and conformity, one of the most challenging parts become the designing antenna for such communication systems. Wearable antennas are the most popular option regarding these issues. Wearable antennas are easier and simpler to mount on clothing when they are made of textile materials. In the process of designing a textile antenna, the availability of the fabrics is pivotal to mount on regularly worn clothes. In this report, several designs of a co-planar waveguide microstrip patch antenna are presented. Instead of felt fabric, the antenna was modified using 100% polyester and cotton fabric for the substrate material. A parasitic patch slot was created on the co-planar ground plane to achieve the dual band resonance frequencies at 2.4 GHz and 5.15 GHz. The geometrical modifications of the antennas were described and their performances were analyzed. The antenna achieved resonating frequency with a thinner substrate as the dielectric constant went higher for the fabrics. The design with different fabric materials was first simulated in CST Microwave Studio, then fabricated and measured in a regular environment. They were also mounted on a 3-D printed human body model to analyze the bending effect. The design of the antennas shows satisfactory performance with a good -10dB bandwidth for both the lower and higher desired resonating frequency band.

A Computer-Aided Approach for Designing Edge-Slot Waveguide Arrays

NASA Technical Reports Server (NTRS)

Gosselin, Renee Brian

2003-01-01

Traditional techniques for designing resonant edge-slot waveguide arrays have required an iterative trial-and-error process of measuring slot data from several prototypes. Since very little meaningful data has been published, this technology remains relatively immature and prohibitive for many smaller programs that could benefit from some advantages this antenna has to offer. A new Computer-Aided Design technique for designing resonant edge-slot waveguide arrays was used to successfuliy design such an X-band radiometer antenna for the NASA Light Rainfall Radiometer (LRR) instrument. Having the ability to rapidly create such an extremely accurate and efficient antenna design without the need to manufacture prototypes has also enabled inexpensive research that promises to improve the system-level performance of microwave radiometers for upcoming space-flight missions. This paper will present details of the LRR antenna design and describe some other current edge-slot array accomplishments at Goddard Space Flight Center.

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-equipped antennas. The antennas were evaluated and optimized in electromagnetic and thermal simulations. Then prototypes of these antennas were fabricated and experimentally characterized in ex vivo ablation experiments. Simulation and experimental results are in good agreement and demonstrate that the proposed antennas provide good impedance matching and localized heating patterns at their operating frequencies while having about 30% smaller diameters compared to conventional coax-fed balun-equipped MWA antennas.

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.

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.

ATCRBS Antenna Modification Kit - Phase I

DOT National Transportation Integrated Search

1973-06-01

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...

Development of a Gimballed, dual frequency, space-based, microwave antenna for volume production

NASA Technical Reports Server (NTRS)

Leckie, Martin; Laidig, Dave

1996-01-01

A dual-frequency, two-axis Gimballed, Microwave Antenna (GMA) has been developed by COM DEV and Motorola for commercial satellites. The need for volume production of over three hundred antennas at a rate of four per week, a compressed development schedule, and the commercial nature of the effort necessitated a paradigm shift to an 'overall' cost-driven design approach. The translation of these demands into antenna requirements, a description of the resulting GMA design, and examples of development issues are detailed herein.

Electronically steerable millimeter wave antenna techniques for space shuttle applications

NASA Technical Reports Server (NTRS)

Kummer, W. H.

1975-01-01

A large multi-function antenna aperture and related components are described which will perform electronic steering of one or more beams for two of the three applications envisioned: (1) communications, (2) radar, and (3) radiometry. The array consists of a 6-meter folded antenna that fits into two pallets. The communications frequencies are 20 and 30 GHz, while the radar is to operate at 13.9 GHz. Weight, prime power, and volumes are given parametrically; antenna designs, electronics configurations, and mechanical design were studied.

A Practical Guide to the Design and Construction of a Single Wire Beverage Antenna.

DTIC Science & Technology

1980-09-01

THEORETICAL PATTERNS 5 5 DESIGN PARAMETERS 7 6 ANTENNA CONSTRUCTION 8 7 ASSESSMENT OF PERFORMANCE 9 8 CONCLUSIONS 9 Tables 1-4 11 References 14...on the main RAE 1906S computer. > The results show the effect at two frequencies of varying the main parameters of antenna height, antenna length...programmes are stored on the main RAE 1906S computer and can be edited prior to running to take into account desired changes in parameters , principally

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

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

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

NASA Astrophysics Data System (ADS)

Shao, Shuai

There is great desire to employ passive UHF RFID tags for inventory tracking and sensing in a diversity of applications and environments. Owing to its battery-free operation, non-line-of sight detection, low cost, long read range and small form factor, each year billions of RFID tags are being deployed in retail, logistics, manufacturing, biomedical inventories, among many other applications. However, the performance of these RFID systems has not met expectations. This is because a tag's performance deteriorates significantly when mounted on or inside arbitrary materials. The tag antenna is optimized only for a given type of material at a certain location of placement, and detuning takes place when attached to or embedded in materials with dielectric properties outside the design range. Thereby, different customized tags may be needed for identifying objects even within the same class of products. This increases the overall cost of the system. Furthermore, conventional copper foil-based RFID tag antennas are prone to metal fatigue and wear, and cannot survive hostile environments where antennas could be deformed by external forces and failures occur. Therefore, it is essential to understand the interaction between the antenna and the material in the vicinity of the tag, and design general purpose RFID tag antennas possessing excellent electrical performance as well as robust mechanical structure. A particularly challenging application addressed here is designing passive RFID tag antennas for automotive tires. Tires are composed of multiple layers of rubber with different dielectric properties and thicknesses. Furthermore, metallic plies are embedded in the sidewalls and steel belts lie beneath the tread to enforce mechanical integrity. To complicate matters even more, a typical tire experiences a 10% stretching during the construction process. This dissertation focuses on intuitively understanding the interaction between the antenna and the material in the proximity and designing broad band and mechanically robust RFID tag antennas for elastic materials. As a first step, the effects of dielectric materials on an antenna's impedance match and radiation pattern are investigated. The detuning effect is quantified based on the theoretical frequency scaling and effective permittivity of a dielectric material of finite thickness. Using simple formulas, the operational range of a tag can be predicted without intensive full-wave simulations of different materials. Next, a spectral domain Green's function is applied to compute the antenna pattern when the tag is mounted on or inside a layered medium. The optimal placement of the tag is found based on the focusing effect that the material has on the gain pattern of the antenna. For tires, the steel ply in the sidewall of a tire looks like a periodic wire grating. The performance of an antenna placed close to a wire grating is predicted using Floquet theory. The results indicate that steel plies embedded in the tire can be utilized as a reflector to further focus the gain pattern and increase the read range of a tag. Using these design tools and theoretical analysis, several broadband RFID tag antennas are designed for multi-layered materials. A novel stretchable conductive textile (E-fiber) based tag antenna is also developed for placement in elastic materials. Prototype antennas are fabricated and embedded in a tire during the tire manufacturing process. Experimental results indicate that tags with the new antennas achieve significant improvement compared with commercially available tags.

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

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.

Co-simulation of a complete rectenna with a circular slot loop antenna in CPW technology

NASA Astrophysics Data System (ADS)

Rivière, Jérôme; Douyère, Alexandre; Cazour, Jonathan; Alicalapa, Frédéric; Luk, Jean-Daniel Lan Sun

2017-05-01

This study starts with the design of a planar and compact CPW antenna fabricated on Arlon AD1000 substrate, ɛr=10.35. The antenna is a coplanar waveguide (CPW) fed circular slot loop antenna matched to the standard impedance 50 Ω by two stubs. The goal is to implement this antenna with a CPW RF/DC rectifier to build an optimized low power level rectenna. The rectenna design is restricted to allow easy and fast fabrication of an array with a high reproducibility. The full rectenna is simulated and achieves 10% effciency at -20 dBm.

Electronic switching spherical array antenna

NASA Technical Reports Server (NTRS)

Stockton, R.

1978-01-01

This work was conducted to demonstrate the performance levels attainable with an ESSA (Electronic Switching Spherical Array) antenna by designing and testing an engineering model. The antenna was designed to satisfy general spacecraft environmental requirements and built to provide electronically commandable beam pointing capability throughout a hemisphere. Constant gain and beam shape throughout large volumetric coverage regions are the principle characteristics. The model is intended to be a prototype of a standard communications and data handling antenna for user scientific spacecraft with the Tracking and Data Relay Satellite System (TDRSS). Some additional testing was conducted to determine the feasibility of an integrated TDRSS and GPS (Global Positioning System) antenna system.

Anti-Jam GPS Antennas for Wearable Dismounted Soldier Navigation Systems

DTIC Science & Technology

2016-06-01

in this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. Citation...Approaches for the design and fabrication of a wearable anti-jam global positioning system (GPS) antenna are explored to support accurate and uninterrupted...including GPS antenna element and array designs , and algorithms for jammer mitigation, and the candidate technologies best fit for wearable anti-jam GPS

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

PubMed

Brace, Christopher L

2011-07-01

Design and validate an efficient dual-slot coaxial microwave ablation antenna that produces an approximately spherical heating pattern to match the shape of most abdominal and pulmonary tumor targets. A dual-slot antenna geometry was utilized for this study. Permutations of the antenna geometry using proximal and distal slot widths from 1 to 10 mm separated by 1-20 mm were analyzed using finite-element electromagnetic simulations. From this series, the most optimal antenna geometry was selected using a two-term sigmoidal objective function to minimize antenna reflection coefficient and maximize the diameter-to-length aspect ratio of heat generation. Sensitivities to variations in tissue properties and insertion depth were also evaluated in numerical models. The most optimal dual-slot geometry of the parametric analysis was then fabricated from semirigid coaxial cable. Antenna reflection coefficients at various insertion depths were recorded in ex vivo bovine livers and compared to numerical results. Ablation zones were then created by applying 50 W for 2-10 min in simulations and ex vivo livers. Mean zone diameter, length, aspect ratio, and reflection coefficients before and after heating were then compared to a conventional monopole antenna using ANOVA with post-hoc t-tests. Statistical significance was indicated for P <0.05. Antenna performance was highly sensitive to dual-slot geometry. The best-performing designs utilized a proximal slot width of 1 mm, distal slot width of 4 mm +/- 1 mm and separation of 8 mm +/- 1 mm. These designs were characterized by an active choking mechanism that focused heating to the distal tip of the antenna. A dual-band resonance was observed in the most optimal design, with a minimum reflection coefficient of -20.9 dB at 2.45 and 1.25 GHz. Total operating bandwidth was greater than 1 GHz, but the desired heating pattern was achieved only near 2.45 GHz. As a result, antenna performance was robust to changes in insertion depth and variations in relative permittivity of the surrounding tissue medium. In both simulations and ex vivo liver, the dual-slot antenna created ablations greater in diameter than a coaxial monopole (35 mm +/- 2 mm versus 31 mm +/- 2 mm; P<0.05), while also shorter in length (49 mm +/- 2 mm versus 60 mm +/- 6 mm; P < 0.001) after 10 min. Similar results were obtained after 2 and 5 min as well. Dual-slot antennas can produce more spherical ablation zones while retaining low reflection coefficients. These benefits are obtained without adding to the antenna diameter. Further evaluation for clinical microwave ablation appears warranted.

Advanced Microstrip Antenna Developments : Volume II. Microstrip GPS Antennas for General Aviation Aircraft

DOT National Transportation Integrated Search

1982-03-01

This report describes the application of microstrip antenna technology to the design of general aviation (G/A) aircraft antennas for use with the Global Positioning System (GPS). For most G/A aircraft, only single frequency operation will be required...

Space station high gain antenna concept definition and technology development

NASA Technical Reports Server (NTRS)

Wade, W. D.

1972-01-01

The layout of a technology base is reported from which a mechanically gimballed, directional antenna can be developed to support a manned space station proposed for the late 1970's. The effort includes the concept definition for the antenna assembly, an evaluation of available technology, the design of critical subassemblies and the design of critical subassembly tests.

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.

Millimeter wave micro-CPW integrated antenna

NASA Astrophysics Data System (ADS)

Tzuang, Ching-Kuang C.; Lin, Ching-Chyuan

1996-12-01

This paper presents the latest result of applying the microstrip's leaky mode for a millimeter-wave active integrated antenna design. In contrast to the use of the first higher-order leaky mode, the second higher-order leaky mode, the second higher-order leaky mode of even symmetry is employed in the new approach, which allows larger dimension for leaky-wave antenna design and thereby reduces its performance sensitivity to the photolithographic tolerance. The new active integrated antenna operating at frequency about 34 GHz comprises of a microstrip and a coplanar waveguide stacked on top of each other, named as the millimeter wave micro-CPW integrated antenna. The feed is through the CPW that would be connected to the active uniplanar millimeter-wave (M)MIC's. Our experimental and theoretical investigations on the new integrated antenna show good input matching characteristics for such a highly directed leaky-wave antenna with the first-pass success.

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.

Advanced microwave radiometer antenna system study

NASA Technical Reports Server (NTRS)

Kummer, W. H.; Villeneuve, A. T.; Seaton, A. F.

1976-01-01

The practicability of a multi-frequency antenna for spaceborne microwave radiometers was considered in detail. The program consisted of a comparative study of various antenna systems, both mechanically and electronically scanned, in relation to specified design goals and desired system performance. The study involved several distinct tasks: definition of candidate antennas that are lightweight and that, at the specified frequencies of 5, 10, 18, 22, and 36 GHz, can provide conical scanning, dual linear polarization, and simultaneous multiple frequency operation; examination of various feed systems and phase-shifting techniques; detailed analysis of several key performance parameters such as beam efficiency, sidelobe level, and antenna beam footprint size; and conception of an antenna/feed system that could meet the design goals. Candidate antennas examined include phased arrays, lenses, and optical reflector systems. Mechanical, electrical, and performance characteristics of the various systems were tabulated for ease of comparison.

Distributed control of large space antennas

NASA Technical Reports Server (NTRS)

Cameron, J. M.; Hamidi, M.; Lin, Y. H.; Wang, S. J.

1983-01-01

A systematic way to choose control design parameters and to evaluate performance for large space antennas is presented. The structural dynamics and control properties for a Hoop and Column Antenna and a Wrap-Rib Antenna are characterized. Some results of the effects of model parameter uncertainties to the stability, surface accuracy, and pointing errors are presented. Critical dynamics and control problems for these antenna configurations are identified and potential solutions are discussed. It was concluded that structural uncertainties and model error can cause serious performance deterioration and can even destabilize the controllers. For the hoop and column antenna, large hoop and long meat and the lack of stiffness between the two substructures result in low structural frequencies. Performance can be improved if this design can be strengthened. The two-site control system is more robust than either single-site control systems for the hoop and column antenna.

Broadbanding of circularly polarized patch antenna by waveguided magneto-dielectric metamaterial

NASA Astrophysics Data System (ADS)

Yang, Xin Mi; Wen, Juan; Liu, Chang Rong; Liu, Xue Guan; Cui, Tie Jun

2015-12-01

Design of bandwidth-enhanced circularly polarized (CP) patch antenna using artificial magneto-dielectric substrate was investigated. The artificial magneto-dielectric material adopted here takes the form of waveguided metamaterial (WG-MTM). In particular, the embedded meander line (EML) structure was employed as the building element of the WG-MTM. As verified by the retrieved effective medium parameters, the EML-based waveguided magneto-dielectric metamaterial (WG-MDM) exhibits two-dimensionally isotropic magneto-dielectric property with respect to TEM wave excitations applied in two orthogonal directions. A CP patch antenna loaded with the EML-based WG-MDM (WG-MDM antenna) has been proposed and its design procedure is described in detail. Simulation results show that the impedance and axial ratio bandwidths of the WG-MDM antenna have increased by 125% and 133%, respectively, compared with those obtained with pure dielectric substrate offering the same patch size. The design of the novel WG-MDM antenna was also validated by measurement results, which show good agreement with their simulated counterparts.

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

PubMed

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

2013-01-01

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

Analysis of dual-frequency MEMS antenna using H-MRTD method

NASA Astrophysics Data System (ADS)

Yu, Wenge; Zhong, Xianxin; Chen, Yu; Wu, Zhengzhong

2004-10-01

For applying micro/nano technologies and Micro-Electro-Mechanical System (MEMS) technologies in the Radio Frequency (RF) field to manufacture miniature microstrip antennas. A novel MEMS dual-band patch antenna designed using slot-loaded and short-circuited size-reduction techniques is presented in this paper. By controlling the short-plane width, the two resonant frequencies, f10 and f30, can be significantly reduced and the frequency ratio (f30/f10) is tunable in the range 1.7~2.3. The Haar-Wavelet-Based multiresolution time domain (H-MRTD) with compactly supported scaling function for a full three-dimensional (3-D) wave to Yee's staggered cell is used for modeling and analyzing the antenna for the first time. Associated with practical model, an uniaxial perfectly matched layer (UPML) absorbing boundary conditions was developed, In addition , extending the mathematical formulae to an inhomogenous media. Numerical simulation results are compared with those using the conventional 3-D finite-difference time-domain (FDTD) method and measured. It has been demonstrated that, with this technique, space discretization with only a few cells per wavelength gives accurate results, leading to a reduction of both memory requirement and computation time.

Space Qualification Testing of a Shape Memory Alloy Deployable CubeSat Antenna

DTIC Science & Technology

2016-09-15

the SMA deployment in the space environment. The HCT QHA successfully passed all required NASA General Environmental Verification Standards space... NASA /JPL parabolic deployable antenna design [28] .................. 19 Figure 11. SERC and NASA /JPL parabolic antenna prototype [28...19 Figure 12. SERC and NASA /JPL parabolic antenna stowed configuration [28] ............. 20 Figure 13. JPL KaPDA antenna [29

Antenna Design Considerations for the Advanced Extravehicular Mobility Unit

NASA Technical Reports Server (NTRS)

Bakula, Casey J.; Theofylaktos, Onoufrios

2015-01-01

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

'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.

Passive coherent location direct signal suppression using hardware mixing techniques

NASA Astrophysics Data System (ADS)

Kaiser, Sean A.; Christianson, Andrew J.; Narayanan, Ram M.

2017-05-01

Passive coherent location (PCL) is a radar technique, in which the system uses reflections from opportunistic illumination sources in the environment for detection and tracking. Typically, PCL uses civilian communication transmitters not ideally suited for radar. The physical geometry of PCL is developed on the basis of bistatic radar without control of the transmitter antenna or waveform design. This poses the problem that often the receiver is designed with two antennas and channels, one for reference and one for surveillance. The surveillance channel is also contaminated with the direct signal and thus direct signal suppression (DSS) techniques must be used. This paper proposes an analytical solution based around hardware for DSS which is compared to other methods available in the literature. The methods are tested in varying bistatic geometries and with varying target radar cross section (RCS) and signal-to-noise ratio (SNR).

Radiation characteristics and polarisation of undulated microstrip line antennas

NASA Astrophysics Data System (ADS)

Shafai, L.; Sebak, A. A.

1985-12-01

A numerical method is used to investigate the radiation from undulated microstrip line antennas. The undulated line is assumed to be suspended over a ground plane and its current distribution is determined using a moment method type solution. This current distribution is then used to compute the co-polar and cross-polar radiation fields. It is found that the current distribution has an oscillating behavior along the line, with a frequency which is twice the number of undulations. The cross-polarization is found to be high and relatively independent of the undulating shape. Its relative level, however, is reduced for large arrays, due to the array factor affecting the co-polar field. A procedure for the reduction or elimination of the cross-polarization is then proposed, which is based on utilizing two undulated lines with mutually inverted undulations. A design method for achieving low sidelobe levels is also proposed and a design example with sidelobes around the -40 dB range is presented.

Ultra-high-frequency microwave response from flexible transparent Au electromagnetic metamaterial nanopatterned antenna

NASA Astrophysics Data System (ADS)

Liu, Dingxin; Niu, Jiebin; Zhu, Haolin; Zhang, Jianyong

2018-02-01

Flexible transparent materials are a hot spot in current research but also a key technical difficulty in industry. They are playing an increasingly important role in flexible transparent display applications such as organic light-emitting diodes, transparent electrodes, and so on. On the other hand, the present research on nanopatterned antennas is mainly concentrated on the optical frequency but rarely on the microwave (such as 3G, 4G, and 5G) and terahertz frequency band communications, where nanopatterned antennas can have many novel applications. To the authors’ knowledge, this is the first paper that presents a method for preparing a flexible transparent Au electromagnetic metamaterial nanopatterned antenna. We study its free-space performance at ultra-high frequency and its application in electronic products such as smartphones, tablets, personal computers, and wearable devices (such as smart watches) which have the function of mobile communication. The experimental results showed that the transparency of the antenna designed and fabricated in this work can be as high as 94%, and its efficiency can reach 74.5%-91.9% of antennas commonly seen at present in academia and industry. By adjusting the capacitive and inductive reactance of the nanopatterned antenna’s matching circuit, combined with its measured efficiency and 3D electromagnetic simulation results, we speculate on the mechanism of the Au electromagnetic metamaterial nanopatterned antenna with good performance.

Development of a high power Helicon system for DIII-D

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

Tooker, Joseph F.; Nagy, Alexander; deGrassie, John

A mechanism for driving current off-axis in high beta tokamaks using fast electromagnetic waves, called Helicons, will be experimentally tested in the DIII-D tokamak. This method is calculated to be more efficient than current drive using electron cyclotron waves or neutral beam injection, and it may be well suited to reactor-like configurations. A low power (100 W) 476 MHz “combline” antenna, consisting of 12 inductively coupled, electrostatically shielded, modular resonators, was recently installed in DIII-D. Initial operation showed that the plasma operating conditions were achieved under which helicon waves can be launched. Plasma operations also showed that the location ofmore » the antenna has not reduced the performance of, or introduced excessive impurities into, the discharges produced in DIII-D. The development of a high power (1 MW) Helicon system is underway. This antenna consists of 30 modules mounted on the inside of the outer wall of the vacuum vessel slightly above the midplane. Carbon tiles around the antenna protect the antenna from thermal plasma streaming along field lines. A 1.2 MW, 476 MHz klystron system will be transferred from the Stanford Linear Accelerator to DIII-D to provide the RF input power to the antenna. Lastly, a description of the design and fabrication of high power antenna and the RF feeds, the klystron and RF distribution systems, and their installation will be presented.« less

Development of a high power Helicon system for DIII-D

DOE PAGES

Tooker, Joseph F.; Nagy, Alexander; deGrassie, John; ...

2017-03-29

A mechanism for driving current off-axis in high beta tokamaks using fast electromagnetic waves, called Helicons, will be experimentally tested in the DIII-D tokamak. This method is calculated to be more efficient than current drive using electron cyclotron waves or neutral beam injection, and it may be well suited to reactor-like configurations. A low power (100 W) 476 MHz “combline” antenna, consisting of 12 inductively coupled, electrostatically shielded, modular resonators, was recently installed in DIII-D. Initial operation showed that the plasma operating conditions were achieved under which helicon waves can be launched. Plasma operations also showed that the location ofmore » the antenna has not reduced the performance of, or introduced excessive impurities into, the discharges produced in DIII-D. The development of a high power (1 MW) Helicon system is underway. This antenna consists of 30 modules mounted on the inside of the outer wall of the vacuum vessel slightly above the midplane. Carbon tiles around the antenna protect the antenna from thermal plasma streaming along field lines. A 1.2 MW, 476 MHz klystron system will be transferred from the Stanford Linear Accelerator to DIII-D to provide the RF input power to the antenna. Lastly, a description of the design and fabrication of high power antenna and the RF feeds, the klystron and RF distribution systems, and their installation will be presented.« less

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

NASA Astrophysics Data System (ADS)

Wainwright, Gregory D.

This dissertations focuses on the development of a novel Ultra-Wideband (UWB) circularly polarized dielectric rod antenna (CPDRA) which yields a constant gain, pattern, and phase center. These properties are important in many applications. Within radar systems a constant phase center is desirable to avoid errors within downrange and crossrange measurements. In a reflector antenna the illumination, spillover, and phase efficiencies will remain the same over an ultra-wideband. Lastly, near field probes require smooth amplitude and phase patterns over frequency to avoid errors during the calibration process of the antenna under test. In this dissertation a novel CP feeding network has been developed for an ultra-wideband dielectric rod antenna. Circularly-polarized antennas have a major advantage over its linearly-polarized counterpart in that the polarization mismatch loss caused by misalignment between the polarizations of the incident fields and antenna can be avoided. This is important in satellite communications and broadcasts where signal propagation through the ionosphere can experience Faraday Rotation. A circularly polarized antenna is also helpful in mobile radar and communication systems where the receiving antennas orientation is not fixed. Previous research on UWB dielectric rod antenna designs has focused on Dual linear feeds. Each polarization within the dual linear feed is excited by a pair of linear launcher arms fed with a 0°-180° hybrid balun. The proposed CPDRA design does not require the 0°-180° hybrid baluns or 0°-90° hybrid for achieving CP operation. These hybrids will increase the antennas size, weight, cost, and reduce operational bandwidth. A design technique has been developed for an UWB multilayer dielectric waveguide used in a CPDRA antenna. This design technique uses near-field Electric field data from inside the waveguide, in conjunction with a genetic algorithm optimization to yield a wideband waveguide with a near field amplitude distribution that scales with frequency. A multilayered dielectric waveguide presents many fabrication challenges. The thermal expansion rates, moisture absorption rates, and vibration properties differ within the various dielectric materials used. Therefore, the development of a wideband waveguide using one material with a low dielectric constant would be advantages since 3-D printing technology can be utilized. In this dissertation novel TE01 and TM01 mode suppressors have been developed using only a single dielectric material.

Feasibility and systems definition study for Microwave Multi-Application Payload (MMAP)

NASA Technical Reports Server (NTRS)

Horton, J. B.; Allen, C. C.; Massaro, M. J.; Zemany, J. L.; Murrell, J. W.; Stanhouse, R. W.; Condon, G. P.; Stone, R. F.; Swana, J.; Afifi, M.

1977-01-01

Work completed on three Shuttle/Spacelab experiments is examined: the Adaptive Multibeam Phased Array Antenna (AMPA) Experiment, Electromagnetic Environment Experiment (EEE) and Millimeter Wave Communications Experiment (MWCE). Results included the definition of operating modes, sequence of operation, radii of operation about several ground stations, signal format, foot prints of typical orbits and preliminary definition of ground and user terminals. Conceptual hardware designs, Spacelab interfaces, data handling methods, experiment testing and verification studies were included. The MWCE-MOD I was defined conceptually for a steerable high gain antenna.

Optical Vector Near-Field Imaging for the Design of Impedance Matched Optical Antennas and Devices

NASA Astrophysics Data System (ADS)

Olmon, Robert L.

Antennas control and confine electromagnetic energy, transforming free-space propagating modes to localized regions. This is not only true for the traditional classical radio antenna, but also for structures that interact resonantly at frequencies throughout the visible regime, that are on the micro- and nanometer size scales. The investigation of these optical antennas has increased dramatically in recent years. They promise to bring the transformative capabilities of radio antennas to the nanoscale in fields such as plasmonics, photonics, spectroscopy, and microscopy. However, designing optical antennas with desired properties is not straightforward due to different material properties and geometric considerations in the optical regime compared to the RF. New antenna characterization tools and techniques must be developed for the optical frequency range. Here, the optical analogue of the vector network analyzer, based on a scattering-type scanning near-field optical microscope, is described and demonstrated for the investigation of the electric and magnetic properties of optical antennas through their electromagnetic vector near-field. Specifically, bringing this microwave frequency tool to the optical regime enables the study of antenna resonant length scaling, optical frequency electromagnetic parameters including current density and impedance, optical antenna coupling to waveguides and nanoloads, local electric field enhancement, and electromagnetic duality of complementary optical antenna geometries.

Inflatable Antenna Microwave Radiometer for Soil Moisture Measurement

NASA Technical Reports Server (NTRS)

Bailey, M. C.; Kendall, Bruce M.; Schroeder, Lyle C.; Harrington, Richard F.

1993-01-01

Microwave measurements of soil moisture are not being obtained at the required spatial Earth resolution with current technology. Recently, new novel designs for lightweight reflector systems have been developed using deployable inflatable antenna structures which could enable lightweight real-aperture radiometers. In consideration of this, a study was conducted at the NASA Langley Research Center (LaRC) to determine the feasibility of developing a microwave radiometer system using inflatable reflector antenna technology to obtain high spatial resolution radiometric measurements of soil moisture from low Earth orbit and which could be used with a small and cost effective launch vehicle. The required high resolution with reasonable swath width coupled with the L-band measurement frequency for soil moisture dictated the use of a large (30 meter class) real aperture antenna in conjunction with a pushbroom antenna beam configuration and noise-injection type radiometer designs at 1.4 and 4.3 GHz to produce a 370 kilometer cross-track swath with a 10 kilometer resolution that could be packaged for launch with a Titan 2 class vehicle. This study includes design of the inflatable structure, control analysis, structural and thermal analysis, antenna and feed design, radiometer design, payload packaging, orbital analysis, and electromagnetic losses in the thin membrane inflatable materials.

Foundations of Broadband Multifunctional Metamaterials Inspired by the Analogy of Formation

DTIC Science & Technology

2013-01-30

25] S. Lim and M.F. Iskander, “ Design of a Dual-Band, Compact Yagi Antenna Over an EBG Ground Plane,’’ IEEE Antennas Wireless Propagat. Lett., vol. 8...For VHF and UHF frequency bands total EBG plus antenna thickness could be prohibitively large. This report presents a unique concept to design and...official Department of the Army position, policy or decision, unless so designated by other documentation. 12. DISTRIBUTION AVAILIBILITY STATEMENT

Calibration of gravitational radiation antenna by dynamic Newton field

NASA Astrophysics Data System (ADS)

Suzuki, T.; Tsubono, K.; Kuroda, K.; Hirakawa, H.

1981-07-01

A method is presented of calibrating antennas for gravitational radiation. The method, which used the dynamic Newton field of a rotating body, is suitable in experiments for frequencies up to several hundred hertz. What is more, the method requires no hardware inside the vacuum chamber of the antenna and is particularly convenient for calibration of low-temperature antenna systems.

Design of band-notched antenna with DG-CEBG

NASA Astrophysics Data System (ADS)

Jaglan, Naveen; Kanaujia, Binod Kumar; Gupta, Samir Dev; Srivastava, Shweta

2018-01-01

Ultra-wideband (UWB) disc monopole antenna with crescent shaped slot for double band-notched features is presented. Planned antenna discards worldwide interoperability for microwave access (WiMAX) band (3.3-3.6 GHz) and wireless local area network (WLAN) band (5-6 GHz). Defected ground compact electromagnetic band gap (DG-CEBG) designs are used to accomplish band notches in WiMAX and WLAN bands. Defected ground planes are utilised to achieve compactness in electromagnetic band gap (EBG) structures. The proposed WiMAX and WLAN DG-CEBG designs show a compactness of around 46% and 50%, respectively, over mushroom EBG structures. Parametric analyses of DG-CEBG design factors are carried out to control the notched frequencies. Stepwise notch transition from upper to lower frequencies is presented with incremental inductance augmentation. The proposed antenna is made-up on low-cost FR-4 substrate of complete extents as (42 × 50 × 1.6) mm3.Fabricated sample antenna shows excellent consistency in simulated and measured outcomes.

A novel approach for the fine tuning of resonance frequency of patch antenna

NASA Astrophysics Data System (ADS)

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

2013-01-01

When a patch antenna is fabricated, dimensions of the patch may be slightly different from the designed values due to tolerances in the fabrication process. This alters the resonance frequency of the antenna. To overcome this problem this paper presents a new design approach for fine tuning the resonance frequency by dielectric constant engineering. This approach is especially suited to low temperature co-fired ceramic (LTCC) and similar processes where the antenna dielectric is composed of several layers. Composite dielectric constant of this multilayer structure is altered in such a way that the resonant frequency is set back to the designed value. It has been verified that for proposed micro strip antenna (MSA) design, the frequency-area curve follows a quadratic relation with a variable R (Ratio of cavity area to the patch area). This mathematical model is true up to R 1.27. After this saturation effects set in and the curve follows a straight line behavior.≡

An optimal structure for a 34-meter millimeter-wave center-fed BWG antenna: The Cross-Box concept

NASA Technical Reports Server (NTRS)

Chuang, K. L.

1988-01-01

An approach to the design of the planned NASA/JPL 34 m elevation-over-azimuth (Az-El) antenna structure at the Venus site (DSS-13) is presented. The antenna structural configuration accommodates a large (2.44 m) beam waveguide (BWG) tube centrally routed through the reflector-alidade structure, an elevation wheel design, and an optimal structural geometry. The design encompasses a cross-box elevation wheel-reflector base substructure that preserves homology while satisfying many constraints, such as structure weight, surface tolerance, stresses, natural frequency, and various functional constraints. The functional requirements are set to ensure that microwave performance at millimeter wavelengths is adequate. The cross-box configuration was modeled, optimized, and found to satisfy all DSN HEF baseline antenna specifications. In addition, the structure design was conceptualized and analyzed with an emphasis on preserving the structure envelope and keeping modifications relative to the HEF antennas to a minimum, thus enabling the transferability of the BWG technology for future retrofitting. Good performance results were obtained.

Deployable Fresnel Rings

NASA Technical Reports Server (NTRS)

Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.; Lin, Gregory Y.

2014-01-01

Deployable Fresnel rings (DFRs) significantly enhance the realizable gain of an antenna. This innovation is intended to be used in combination with another antenna element, as the DFR itself acts as a focusing or microwave lens element for a primary antenna. This method is completely passive, and is also completely wireless in that it requires neither a cable, nor a connector from the antenna port of the primary antenna to the DFR. The technology improves upon the previous NASA technology called a Tri-Sector Deployable Array Antenna in at least three critical aspects. In contrast to the previous technology, this innovation requires no connector, cable, or other physical interface to the primary communication radio or sensor device. The achievable improvement in terms of antenna gain is significantly higher than has been achieved with the previous technology. Also, where previous embodiments of the Tri-Sector antenna have been constructed with combinations of conventional (e.g., printed circuit board) and conductive fabric materials, this innovation is realized using only conductive and non-conductive fabric (i.e., "e-textile") materials, with the possible exception of a spring-like deployment ring. Conceptually, a DFR operates by canceling the out-of-phase radiation at a plane by insertion of a conducting ring or rings of a specific size and distance from the source antenna, defined by Fresnel zones. Design of DFRs follow similar procedures to those outlined for conventional Fresnel zone rings. Gain enhancement using a single ring is verified experimentally and through computational simulation. The experimental test setup involves a microstrip patch antenna that is directly behind a single-ring DFR and is radiating towards a second microstrip patch antenna. The first patch antenna and DFR are shown. At 2.42 GHz, the DFR improves the transmit antenna gain by 8.6 dB, as shown in Figure 2, relative to the wireless link without the DFR. A figure illustrates the relative strength of power coupling between the first and second microstrip antennas with and without the DFR. Typically, a DFR is designed for use at a particular frequency; however, testing of a DFR indicated a relatively wide operational bandwidth of approximately 8.2%. Wider bandwidth operation and multi-band operation are anticipated by extending the known art of conventional Fresnel rings to the DFRs. Increasing the number of rings used to construct a DFR antenna increases the gain, with the upper bound limited often by the largest practical dimensions that can be tolerated for a given application. The maximum theoretical improvement in gain for a single ring is 9.5 dB. Experimental results are within 0.9 dB of this theoretical value. Adding rings increases gain, and theoretically, improvements of 10 to 13 dB above that of the primary antenna gain can be achieved with two- and three-ring versions.

Hybrid RF / Optical Communication Terminal with Spherical Primary Optics for Optical Reception

NASA Technical Reports Server (NTRS)

Charles, Jeffrey R.; Hoppe, Daniel H.; Sehic, Asim

2011-01-01

Future deep space communications are likely to employ not only the existing RF uplink and downlink, but also a high capacity optical downlink. The Jet Propulsion Laboratory (JPL) is currently investigating the benefits of a ground based hybrid RF and deep space optical terminal based on limited modification of existing 34 meter antenna designs. The ideal design would include as large an optical aperture as technically practical and cost effective, cause minimal impact to RF performance, and remain cost effective even when compared to a separate optical terminal of comparable size. Numerous trades and architectures have been considered, including shared RF and optical apertures having aspheric optics and means to separate RF and optical signals, plus, partitioned apertures in which various zones of the primary are dedicated to optical reception. A design based on the latter is emphasized in this paper, employing spherical primary optics and a new version of a "clamshell" corrector that is optimized to fit within the limited space between the antenna sub-reflector and the existing apex structure that supports the subreflector. The mechanical design of the hybrid accommodates multiple spherical primary mirror panels in the central 11 meters of the antenna, and integrates the clamshell corrector and optical receiver modules with antenna hardware using existing attach points to the maximum extent practical. When an optical collection area is implemented on a new antenna, it is possible to design the antenna structure to accommodate the additional weight of optical mirrors providing an equivalent aperture of several meters diameter. The focus of our near term effort is to use optics with the 34 meter DSS-13 antenna at Goldstone to demonstrate spatial optical acquisition and tracking capability using an optical system that is temporarily integrated into the antenna.

Gaussian-Beam/Physical-Optics Design Of Beam Waveguide

NASA Technical Reports Server (NTRS)

Veruttipong, Watt; Chen, Jacqueline C.; Bathker, Dan A.

1993-01-01

In iterative method of designing wideband beam-waveguide feed for paraboloidal-reflector antenna, Gaussian-beam approximation alternated with more nearly exact physical-optics analysis of diffraction. Includes curved and straight reflectors guiding radiation from feed horn to subreflector. For iterative design calculations, curved mirrors mathematically modeled as thin lenses. Each distance Li is combined length of two straight-line segments intersecting at one of flat mirrors. Method useful for designing beam-waveguide reflectors or mirrors required to have diameters approximately less than 30 wavelengths at one or more intended operating frequencies.

Best of Breed

NASA Technical Reports Server (NTRS)

Lohn, Jason

2004-01-01

No team of engineers, no matter how much time they took or how many bottles of cabernet they consumed, would dream up an antenna that looked like a deer antler on steroids. Yet that's what a group at NASA Ames Research Center came up with-thanks to a little help from Darwin. NASA's Space Technology 5 nanosatellites, which are scheduled to start measuring Earth's magnetosphere in late 2004, requires an antenna that can receive a wide range of frequencies regardless of the spacecraft's orientation. Rather than leave such exacting requirements in the hands of a human, the engineers decided to breed a design using genetic algorithms and 32 Linux PCs. The computers generated small antenna-constructing programs (the genotypes) and executed them to produce designs (the phenotypes). Then the designs were evaluated using an antenna simulator. The team settled on the form pictured here. You won't find this kind of antenna in any textbook, design guide, or research paper. But its innovative structure meets a challenging set of specifications. If successfully deployed, it will be the first evolved antenna to make it out of the lab and the first piece of evolved hardware ever to fly in space.

Antenna Construction and Propagation of Radio Waves.

ERIC Educational Resources Information Center

Marine Corps Inst., Washington, DC.

Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on antenna construction and propagation of radio waves is designed to provide communicators with instructions in the selection and/or construction of the proper antenna(s) for use with current field radio equipment. Introductory materials include…

Gravitation research

NASA Technical Reports Server (NTRS)

Weiss, R.; Muehlner, D. J.; Benford, R. L.; Owens, D. K.; Pierre, N. A.; Rosenbluh, M.

1972-01-01

Balloon measurements were made of the far infrared background radiation. The radiometer used and its calibration are discussed. An electromagnetically coupled broadband gravitational antenna is also considered. The proposed antenna design and noise sources in the antenna are reviewed. A comparison is made between interferometric broadband and resonant bar antennas for the detection of gravitational wave pulses.

Studies of RF sheaths and diagnostics on IShTAR

NASA Astrophysics Data System (ADS)

Crombé, K.; Devaux, S.; D'Inca, R.; Faudot, E.; Faugel, H.; Fünfgelder, H.; Heuraux, S.; Jacquot, J.; Louche, F.; Moritz, J.; Ochoukov, R.; Tripsky, M.; Van Eester, D.; Wauters, T.; Noterdaeme, J.-M.

2015-12-01

IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetised plasma test facility for RF sheaths studies at the Max-Planck-Institut für Plasmaphysik in Garching. In contrast to a tokamak, a test stand provides more liberty to impose the parameters and gives better access for the instrumentation and antennas. The project will support the development of diagnostic methods for characterising RF sheaths and validate and improve theoretical predictions. The cylindrical vacuum vessel has a diameter of 1 m and is 1.1 m long. The plasma is created by an external cylindrical plasma source equipped with a helical antenna that has been designed to excite the m=1 helicon mode. In inductive mode, plasma densities and electron temperatures have been characterised with a planar Langmuir probe as a function of gas pressure and input RF power. A 2D array of RF compensated Langmuir probes and a spectrometer are planned. A single strap RF antenna has been designed; the plasma-facing surface is aligned to the cylindrical plasma to ease the modelling. The probes will allow direct measurements of plasma density profiles in front of the RF antenna, and thus a detailed study of the density modifications induced by RF sheaths, which influences the coupling. The RF antenna frequency has been chosen to study different plasma wave interactions: the accessible plasma density range includes an evanescent and propagative behaviour of slow or fast waves, and allows the study of the effect of the lower hybrid resonance layer.

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.

Design and optimization of an ultra wideband and compact microwave antenna for radiometric monitoring of brain temperature.

PubMed

Rodrigues, Dario B; Maccarini, Paolo F; Salahi, Sara; Oliveira, Tiago R; Pereira, Pedro J S; Limao-Vieira, Paulo; Snow, Brent W; Reudink, Doug; Stauffer, Paul R

2014-07-01

We present the modeling efforts on antenna design and frequency selection to monitor brain temperature during prolonged surgery using noninvasive microwave radiometry. A tapered log-spiral antenna design is chosen for its wideband characteristics that allow higher power collection from deep brain. Parametric analysis with the software HFSS is used to optimize antenna performance for deep brain temperature sensing. Radiometric antenna efficiency (η) is evaluated in terms of the ratio of power collected from brain to total power received by the antenna. Anatomical information extracted from several adult computed tomography scans is used to establish design parameters for constructing an accurate layered 3-D tissue phantom. This head phantom includes separate brain and scalp regions, with tissue equivalent liquids circulating at independent temperatures on either side of an intact skull. The optimized frequency band is 1.1-1.6 GHz producing an average antenna efficiency of 50.3% from a two turn log-spiral antenna. The entire sensor package is contained in a lightweight and low-profile 2.8 cm diameter by 1.5 cm high assembly that can be held in place over the skin with an electromagnetic interference shielding adhesive patch. The calculated radiometric equivalent brain temperature tracks within 0.4 °C of the measured brain phantom temperature when the brain phantom is lowered 10 °C and then returned to the original temperature (37 °C) over a 4.6-h experiment. The numerical and experimental results demonstrate that the optimized 2.5-cm log-spiral antenna is well suited for the noninvasive radiometric sensing of deep brain temperature.

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

A validation study of the simulation software gprMax by varying antenna stand-off height

NASA Astrophysics Data System (ADS)

Wilkinson, Josh; Davidson, Nigel

2018-04-01

The design and subsequent testing of suitable antennas and of complete ground-penetrating radar (GPR) systems can be both time consuming and expensive, with the need to understand the performance of a system in realistic environments of great importance to the end user. Through the use of suitably validated simulations, these costs could be significantly reduced, allowing an economical capability to be built which can accurately predict the performance of novel GPR antennas and existing commercial-off-the-shelf (COTS) systems in a user defined environment. This paper focuses on a preliminary validation of the open source software gprMax1 which features the ability to custom define antennas, targets, clutter objects and realistic heterogeneous soils. As an initial step in the assessment of the software, a comparison of the modelled response of targets buried in sand to experimental data has been undertaken, with the variation in response with antenna stand-off height investigated. This was conducted for both a simple bespoke bow-tie antenna design as well as for a Geophysical Survey Systems, Inc. (GSSI) commercial system,2 building upon previous work3 which explored the fidelity of gprMax in reproducing the S11 of simple antenna designs.

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.

Design of WLAN microstrip antenna for 5.17 - 5.835 GHz

NASA Astrophysics Data System (ADS)

Bugaj, Jarosław; Bugaj, Marek; Wnuk, Marian

2017-04-01

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

Breakthroughs in Low-Profile Leaky-Wave HPM Antennas

DTIC Science & Technology

2015-03-18

presentation of our work at the 17th annual DEPS conference. 15. SUBJECT TERMS Leaky-wave Antennas. High Power Microwaves (HPM) Antennas. Low-profile...the performance, behavior, and design of innovative High Power Microwave (HPM, GW-class) antennas of the forward-traveling, fast-wave, leaky-wave...Conformal Antennas. 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON (Monitor

Compact, Lightweight Dual-Frequency Microstrip Antenna Feed for Future Soil Moisture and Sea Surface Salinity Missions

NASA Technical Reports Server (NTRS)

Yueh, Simon; Wilson, William J.; Njoku, Eni; Dinardo, Steve; Hunter, Don; Rahmat-Samii, Yahya; Kona, Keerti S.; Manteghi, Majid

2006-01-01

The development of a compact, lightweight, dual-frequency antenna feed for future soil moisture and sea surface salinity (SSS) missions is described. The design is based on the microstrip stacked-patch array (MSPA) to be used to feed a large lightweight deployable rotating mesh antenna for spaceborne L-band (approx.1 GHz) passive and active sensing systems. The design features will also enable applications to airborne soil moisture and salinity remote sensing sensors operating on small aircrafts. This paper describes the design of stacked patch elements and 16-element array configuration. The results from the return loss, antenna pattern measurements and sky tests are also described.

Manufacture of a conformal multilayer rf antenna substrate using excimer mask imaging technology and a 6-axis robot

NASA Astrophysics Data System (ADS)

Charrier, Michel; Everett, Daniel; Fieret, Jim; Karrer, Tobias; Rau, Sven; Valard, Jean-Luc

2001-06-01

A novel method is presented to produce a high precision pattern of copper tracks on both sides of a 4-layer conformal radar antenna made of PEI polymer and shaped as a truncated pseudo-parabolic cylinder. The antenna is an active emitter-receiver so that an accuracy of a fraction of the wavelength of the microwave radiation is required. After 2D layer design in Allegro, the resulting Gerber file-format circuits are wrapped around the antenna shape, resulting in a cutter-path file which provides the input for a postprocessor that outputs G-code for robot- and laser control. A rules file contains embedded information such as laser parameters and mask aperture related to the Allegro symbols. The robot consists of 6 axes that manipulate the antenna, and 2 axes for the mask plate. The antenna can be manipulated to an accuracy of +/- 20 micrometers over its full dimensions of 200x300x50 mm. The four layers are constructed by successive copper coating, resist coating, laser ablation, copper etching, resist removal, insulation polyimide film lamination and laser dielectric drilling for microvia holes and through-holes drilling. Applications are in space and aeronautical communication and radar detection systems, with possible extensions to automotive and mobile hand-sets, and land stations.

Interventional MRI: tapering improves the distal sensitivity of the loopless antenna.

PubMed

Qian, Di; El-Sharkawy, AbdEl-Monem M; Atalar, Ergin; Bottomley, Paul A

2010-03-01

The "loopless antenna" is an interventional MRI detector consisting of a tuned coaxial cable and an extended inner conductor or "whip". A limitation is the poor sensitivity afforded at, and immediately proximal to, its distal end, which is exacerbated by the extended whip length when the whip is uniformly insulated. It is shown here that tapered insulation dramatically improves the distal sensitivity of the loopless antenna by pushing the current sensitivity toward the tip. The absolute signal-to-noise ratio is numerically computed by the electromagnetic method-of-moments for three resonant 3-T antennae with no insulation, uniform insulation, and with linearly tapered insulation. The analysis shows that tapered insulation provides an approximately 400% increase in signal-to-noise ratio in trans-axial planes 1 cm from the tip and a 16-fold increase in the sensitive area as compared to an equivalent, uniformly insulated antenna. These findings are directly confirmed by phantom experiments and by MRI of an aorta specimen. The results demonstrate that numerical electromagnetic signal-to-noise ratio analysis can accurately predict the loopless detector's signal-to-noise ratio and play a central role in optimizing its design. The manifold improvement in distal signal-to-noise ratio afforded by redistributing the insulation should improve the loopless antenna's utility for interventional MRI. (c) 2010 Wiley-Liss, Inc.

A Phase Correction Technique Based on Spatial Movements of Antennas in Real-Time (S.M.A.R.T.) for Designing Self-Adapting Conformal Array Antennas

NASA Astrophysics Data System (ADS)

Roy, Sayan

This research presents a real-time adaptive phase correction technique for flexible phased array antennas on conformal surfaces of variable shapes. Previously reported pattern correctional methods for flexible phased array antennas require prior knowledge on the possible non-planar shapes in which the array may adapt for conformal applications. For the first time, this initial requirement of shape curvature knowledge is no longer needed and the instantaneous information on the relative location of array elements is used here for developing a geometrical model based on a set of Bezier curves. Specifically, by using an array of inclinometer sensors and an adaptive phase-correctional algorithm, it has been shown that the proposed geometrical model can successfully predict different conformal orientations of a 1-by-4 antenna array in real-time without the requirement of knowing the shape-changing characteristics of the surface the array is attached upon. Moreover, the phase correction technique is validated by determining the field patterns and broadside gain of the 1-by-4 antenna array on four different conformal surfaces with multiple points of curvatures. Throughout this work, measurements are shown to agree with the analytical solutions and full-wave simulations.

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

A Review of Passive RFID Tag Antenna-Based Sensors and Systems for Structural Health Monitoring Applications.

PubMed

Zhang, Jun; Tian, Gui Yun; Marindra, Adi M J; Sunny, Ali Imam; Zhao, Ao Bo

2017-01-29

In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well.

An extraordinary transmission analogue for enhancing microwave antenna performance

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

Pushpakaran, Sarin V., E-mail: sarincrema@gmail.com; Purushothaman, Jayakrishnan M.; Chandroth, Aanandan

2015-10-15

The theory of diffraction limit proposed by H.A Bethe limits the total power transfer through a subwavelength hole. Researchers all over the world have gone through different techniques for boosting the transmission through subwavelength holes resulting in the Extraordinary Transmission (EOT) behavior. We examine computationally and experimentally the concept of EOT nature in the microwave range for enhancing radiation performance of a stacked dipole antenna working in the S band. It is shown that the front to back ratio of the antenna is considerably enhanced without affecting the impedance matching performance of the design. The computational analysis based on Finitemore » Difference Time Domain (FDTD) method reveals that the excitation of Fabry-Perot resonant modes on the slots is responsible for performance enhancement.« less

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.

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

An experimental investigation of high temperature superconducting microstrip antennas at K- and Ka-band frequencies. Ph.D. Thesis Final Report

NASA Technical Reports Server (NTRS)

Richard, Mark A.

1993-01-01

The recent discovery of high temperature superconductors (HTS) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS results in narrow bandwidths and high patch edge impedances of such antennas. To investigate the performance of superconducting microstrip antennas, three antenna architectures at K and Ka-band frequencies are examined. Superconducting microstrip antennas that are directly coupled, gap coupled, and electromagnetically coupled to a microstrip transmission line were designed and fabricated on lanthanum aluminate substrates using YBa2Cu3O7 superconducting thin films. For each architecture, a single patch antenna and a four element array were fabricated. Measurements from these antennas, including input impedance, bandwidth, patterns, efficiency, and gain are presented. The measured results show usable antennas can be constructed using any of the architectures. All architectures show excellent gain characteristics, with less than 2 dB of total loss in the four element arrays. Although the direct and gap coupled antennas are the simplest antennas to design and fabricate, they suffer from narrow bandwidths. The electromagnetically coupled antenna, on the other hand, allows the flexibility of using a low permittivity substrate for the patch radiator, while using HTS for the feed network, thus increasing the bandwidth while effectively utilizing the low loss properties of HTS. Each antenna investigated in this research is the first of its kind reported.

A liquid metal-based structurally embedded vascular antenna: I. Concept and multiphysical modeling

NASA Astrophysics Data System (ADS)

Hartl, D. J.; Frank, G. J.; Huff, G. H.; Baur, J. W.

2017-02-01

This work proposes a new concept for a reconfigurable structurally embedded vascular antenna (SEVA). The work builds on ongoing research of structurally embedded microvascular systems in laminated structures for thermal transport and self-healing and on studies of non-toxic liquid metals for reconfigurable electronics. In the example design, liquid metal-filled channels in a laminated composite act as radiating elements for a high-power planar zig-zag wire log periodic dipole antenna. Flow of liquid metal through the channels is used to limit the temperature of the composite in which the antenna is embedded. A multiphysics engineering model of the transmitting antenna is formulated that couples the electromagnetic, fluid, thermal, and mechanical responses. In part 1 of this two-part work, it is shown that the liquid metal antenna is highly reconfigurable in terms of its electromagnetic response and that dissipated thermal energy generated during high power operation can be offset by the action of circulating or cyclically replacing the liquid metal such that heat is continuously removed from the system. In fact, the SEVA can potentially outperform traditional copper-based antennas in high-power operational configurations. The coupled engineering model is implemented in an automated framework and a design of experiment study is performed to quantify first-order design trade-offs in this multifunctional structure. More rigorous design optimization is addressed in part 2.

Radio-Frequency and Wideband Modulation Arraying

NASA Technical Reports Server (NTRS)

Brockman, M. H.

1984-01-01

Summing network receives coherent signals from all receivers in array. Method sums narrow-band radio-frequency (RF) carrier powers and wide-band spectrum powers of array of separate antenna/receiver systems designed for phase-locked-loop or suppressed-carrier operation.

Methods and apparatus for vertical coupling from dielectric waveguides

DOEpatents

Yaacobi, Ami; Cordova, Brad Gilbert

2014-06-17

A frequency-chirped nano-antenna provides efficient sub-wavelength vertical emission from a dielectric waveguide. In one example, this nano-antenna includes a set of plasmonic dipoles on the opposite side of a SiYV.sub.4 waveguide from a ground plane. The resulting structure, which is less than half a wavelength long, emits a broadband beam (e.g., >300 nm) that can be coupled into an optical fiber. In some embodiments, a diffractive optical element with unevenly shaped regions of high- and low-index dielectric material collimates the broadband beam for higher coupling efficiency. In some cases, a negative lens element between the nano-antenna and the diffractive optical element accelerates the emitted beam's divergence (and improves coupling efficiency), allowing for more compact packaging. Like the diffractive optical element, the negative lens element includes unevenly shaped regions of high- and low-index dielectric material that can be designed to compensate for aberrations in the beam emitted by the nano-antenna.

A common-aperture X- and S-band four-function feedcone. [hornfeed design for antennas of Deep Space Network

NASA Technical Reports Server (NTRS)

Withington, J. R.; Williams, W. F.

1982-01-01

Williams and Withington (1979) have considered a prototype X-S-band feedhorn which enabled simultaneous X- and S-band reception from a Cassegrain antenna. This feedhorn has quite successfully demonstrated an alternate method to the standard Deep Space Network (DSN) system of multiple subreflectors and dichroic plate for dual-band reception. In connection with a Network Consolidation Program, involving centralized control of existing antennas and construction of new reflector antennas, a second-generation feedhorn/combiner was conceived to show that this common-aperture feedhorn system was capable of performing all necessary functions the DSN would be called upon to perform with existing and future X-S-band spacecraft. Attention is given to the feedhorn concept, the combiner concept, the first and the second generation of the horn, Sand X-band tuning, and planned capabilities. The feedhorn greatly extends the state of the art in DSN performance and will enhance DSN capabilities in the future.

Structural optimization and recent large ground antenna installations

NASA Technical Reports Server (NTRS)

Levy, Roy

1989-01-01

Within the past several years, the Jet Propulsion Laboratory has designed and built major ground antenna structures in Spain, Australia, and California. One of the antennas at each location is a 70 meter-diameter structure that is a retrofit of the existing 64 meter antenna. The 64 meter existing antennas were first stripped back to a 34 meter interior and then completely new construction with deeper trusses was added to extend the interior to 70 meters. The 70 meter project included the rare opportunity to collect field data to compare with predictions of the finite-element analytical models. The new quadripod design was tested for its lower mode natural frequencies and the main reflector was measured by theodolite to determine deflections of subsets of the backup-structure deformations under load. The emphasis here is to examine measurement results and possibly provide some appreciation of the relationship of predictions made from the design model to actual measurements.

Closely Coupled Multi-Mode Radiators: A New Concept for Improving the Perfomance of Electrically Small Antennas

DTIC Science & Technology

2015-11-23

realized gain values of−5.0 dBiC and 3.1 dBiC, respectively. Details of the design, optimization, simulation, and the measured results of the fabricated...prototype of this Fig. 4. The measured input VSWR of the antenna prototype shown in Fig. 3. 7    antenna were published in IEEE Transactions on...suppressed. Other prototypes of these types of MEFSSs were also designed and fabricated and characterized. Details of the design and measurement

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.

Thermal effects of optical antenna under the irradiation of laser

NASA Astrophysics Data System (ADS)

Sun, Yi; Li, Fu; Yang, Wenqiang; Yang, Jianfeng

2017-10-01

The laser communication terminal is a precision optical, mechanical, electrical integration device which operations extremely high accuracy. It is hard to improve the space environment adaptability in the hash vibration, thermal cycling, high vacuum and radiation conditions space environment. Accordingly, the optical antenna will be influenced by space thermal environment. Laser energy will be absorbed when optical antenna under the irradiation of laser. It can contribute to thermal distortion and make the beam quality degradation which affects the performance of laser communications links. This influence will aggravate when the laser power rising.Wavefront aberration is the distance between the ideal reference sphere and the actual distorted wavefront. The smaller the wavefront aberration, the better the optical performance of the optical antenna. On the contrary, the greater the wavefront aberration, the worse the performance of the optical antenna or even affect the normal operation of the optical antenna. The performance index of the optical antenna generally requires the wavefront aberration to be better than λ/20. Due to the different thermal and thermal expansion coefficients of the material, the effect of thermal deformation on the optical antenna can be reduced by matching the appropriate material. While the appropriate support structure and proper heat dissipation design can also reduce the impact. In this paper, the wavefront aberration of the optical antenna is better than λ/50 by the material matching and the appropriate support structure and the secondary design of the diameter of 5mm hole thermal design.

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.

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.

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

NASA Astrophysics Data System (ADS)

Reynolds, Nathan D.

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

Two-Stage Design Method for Enhanced Inductive Energy Transmission with Q-Constrained Planar Square Loops.

PubMed

Eteng, Akaa Agbaeze; Abdul Rahim, Sharul Kamal; Leow, Chee Yen; Chew, Beng Wah; Vandenbosch, Guy A E

2016-01-01

Q-factor constraints are usually imposed on conductor loops employed as proximity range High Frequency Radio Frequency Identification (HF-RFID) reader antennas to ensure adequate data bandwidth. However, pairing such low Q-factor loops in inductive energy transmission links restricts the link transmission performance. The contribution of this paper is to assess the improvement that is reached with a two-stage design method, concerning the transmission performance of a planar square loop relative to an initial design, without compromise to a Q-factor constraint. The first stage of the synthesis flow is analytical in approach, and determines the number and spacing of turns by which coupling between similar paired square loops can be enhanced with low deviation from the Q-factor limit presented by an initial design. The second stage applies full-wave electromagnetic simulations to determine more appropriate turn spacing and widths to match the Q-factor constraint, and achieve improved coupling relative to the initial design. Evaluating the design method in a test scenario yielded a more than 5% increase in link transmission efficiency, as well as an improvement in the link fractional bandwidth by more than 3%, without violating the loop Q-factor limit. These transmission performance enhancements are indicative of a potential for modifying proximity HF-RFID reader antennas for efficient inductive energy transfer and data telemetry links.

Time-Zone-Pattern Satellite Broadcasting Antenna

NASA Technical Reports Server (NTRS)

Galindo, Victor; Rahmat-Samii, Yahya; Imbriale, William A.; Cohen, Herb; Cagnon, Ronald R.

1988-01-01

Direct-broadcast satellite antenna designs provide contoured beams to match four time zones in 48 contiguous states and spot beams for Alaska, Hawaii, and Puerto Rico presented in 29-page report. Includes descriptions of procedures used to arrive at optimized designs. Arrangements, amplitudes, and phases of antenna feeds presented in tables. Gain contours shown graphically. Additional tables of performance data given for cities in service area of Eastern satellite.

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

NASA Technical Reports Server (NTRS)

Raines, J. K.

1975-01-01

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

Multiple-Feed Design For DSN/SETI Antenna

NASA Technical Reports Server (NTRS)

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

1988-01-01

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

Evolutionary Optimization of Quadrifilar Helical and Yagi-Uda Antennas

NASA Technical Reports Server (NTRS)

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

2002-01-01

We present optimization results obtained for two type of antennas using evolutionary algorithms. A quadrifilar helical UHF antenna is currently flying aboard NASA's Mars Odyssey spacecraft and is due to reach final Martian orbit insertion in January, 2002. Using this antenna as a benchmark, we ran experiments employing a coevolutionary genetic algorithm to evolve a quadrifilar helical design in-situ - i.e., in the presence of a surrounding structure. Results show a 93% improvement at 400 MHz and a 48% improvement at 438 MHz in the average gain. The evolved antenna is also one-fourth the size. Yagi-Uda antennas are known to be difficult to design and optimize due to their sensitivity at high gain and the inclusion of numerous parasitic elements. Our fitness calculation allows the implicit relationship between power gain and sidelobe/backlobe loss to emerge naturally, a technique that is less complex than previous approaches. Our results include Yagi-Uda antennas that have excellent bandwidth and gain properties with very good impedance characteristics. Results exceeded previous Yagi-Uda antennas produced via evolutionary algorithms by at least 7.8% in mainlobe gain.

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

PubMed Central

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

2014-01-01

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

Microcomputer design and analysis of the cable catenary large space antenna system

NASA Technical Reports Server (NTRS)

Akle, W.

1984-01-01

The use of microcomputers in the design of a cable catenary large space antenna system is discussed. The development of a system design capability, data base utilization, systems integration, program structure and logic, and integrated graphics output are discussed.

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

NASA Astrophysics Data System (ADS)

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

2009-04-01

A full polarimetric antenna system on board the ExoMars rover is part of the Experiment "Water Ice and Subsurface Deposit Observations on Mars" (WISDOM). The WISDOM-Experiment is a Ground Penetrating Radar (GPR) selected to be part of the Pasteur payload aboard the rover of the ExoMars mission. The Pasteur Panoramic Instruments (wide angle camera PANCAM, infrared spectrometer MIMA and WISDOM) will perform large-scale scientific investigations at the sites the Rover will visit. Among these instruments, WISDOM is the only one that can provide a view of the subsurface structure prior to drilling. WISDOM is the first space borne GPR aboard a rover and has been designed to characterize the shallow subsurface structure of Mars. WISDOM will give for the first time access to the geological structure, electromagnetic nature, and, possibly, of hydrological state of the shallow subsurface by retrieving the layering and properties of the buried reflectors. It will address some important related science questions regarding the planet present state and past evolution. The measured data will also be used to determine the most promising locations at which to obtain underground samples with the drilling system mounted on board the rover. The instrument objective for WISDOM is to get high-resolution measurements down to 2-meters depth in the Martian crust. The radar is a gated step frequency system covering the frequency range from 500 MHz to 3 GHz. The radar is fully polarimetric and makes use of four ultra wideband Vivaldi antennas. This poster describes the requirements, the design and the realization of the WISDOM antenna system accommodated on the ExoMars rover. Simulated antenna performance and measured antenna parameters as well as preliminary antenna test measurements performed in the lab and in permafrost regions on earth will be discussed in this poster presentation. The main design requirements of the WISDOM antenna system are driven one hand by the required science return of the Experiment and on the other hand by the specific GPR configuration and accommodation on the Mars Rover. The resolution of a few centimetres and a penetration depth of more than two meters results in a bandwidth of 2.5 GHz. To be able to study depolarization effects in the subsurface a fully polarimetric antenna system is required. To realize the best radar performance the antenna system is equipped with two perpendicular linear polarized transmitting antennas and two co- and cross-polar oriented antennas for reception. Usually GPR antennas are placed on ground or accommodated in a close-by ground configuration with respect to the wavelength. Considering the requirements for the design of the ExoMars rover the GPR antenna system has to have a ground clearance of about 30 cm, which is equal to 3 wavelengths for the highest operating frequency. Taking into account that the GPR antennas on the rover are not able to use the advantages of a close-by ground arrangement and that due to mass, volume and planetary protection requirements the application of absorbing material and reflectors are not appropriate, the antenna pattern of each single antenna element should be directed towards ground and should provide a large forward to backward ratio. The radiation pattern should be wide in rover path direction, so that a visibility of point reflectors for long distance is possible. The across path pattern should be narrow. These and other constraints like EMC requirements as well as pattern deformation due to radiation coupling effects with the rover structure led to an antenna design that is based on two perpendicular oriented Vivaldi structures for each antenna. The antennas will be covered by thin dielectric foil to protect the sensitive parts from Martian dust particles. The overall size of the dual polarized transmitting and receiving antenna is less than 20 cm x 20 cm x 20 cm. The total mass for a whole antenna unit is about 200 g. Taking into account all the requirements, a very powerful space qualified broad band antenna system is developed and successfully tested in different environments.

Measurement of Antenna Bore-Sight Gain

NASA Technical Reports Server (NTRS)

Fortinberry, Jarrod; Shumpert, Thomas

2016-01-01

The absolute or free-field gain of a simple antenna can be approximated using standard antenna theory formulae or for a more accurate prediction, numerical methods may be employed to solve for antenna parameters including gain. Both of these methods will result in relatively reasonable estimates but in practice antenna gain is usually verified and documented via measurements and calibration. In this paper, a relatively simple and low-cost, yet effective means of determining the bore-sight free-field gain of a VHF/UHF antenna is proposed by using the Brewster angle relationship.

Microstrip Antenna for Remote Sensing of Soil Moisture and Sea Surface Salinity

NASA Technical Reports Server (NTRS)

Ramhat-Samii, Yahya; Kona, Keerti; Manteghi, Majid; Dinardo, Steven; Hunter, Don; Njoku, Eni; Wilson, Wiliam; Yueh, Simon

2009-01-01

This compact, lightweight, dual-frequency antenna feed developed for future soil moisture and sea surface salinity (SSS) missions can benefit future soil and ocean studies by lowering mass, volume, and cost of the antenna system. It also allows for airborne soil moisture and salinity remote sensors operating on small aircraft. While microstrip antenna technology has been developed for radio communications, it has yet to be applied to combined radar and radiometer for Earth remote sensing. The antenna feed provides a key instrument element enabling high-resolution radiometric observations with large, deployable antennas. The design is based on the microstrip stacked-patch array (MSPA) used to feed a large, lightweight, deployable, rotating mesh antenna for spaceborne L-band (approximately equal to 1 GHz) passive and active sensing systems. The array consists of stacked patches to provide dual-frequency capability and suitable radiation patterns. The stacked-patch microstrip element was designed to cover the required L-band center frequencies at 1.26 GHz (lower patch) and 1.413 GHz (upper patch), with dual-linear polarization capabilities. The dimension of patches produces the required frequencies. To achieve excellent polarization isolation and control of antenna sidelobes for the MSPA, the orientation of each stacked-patch element within the array is optimized to reduce the cross-polarization. A specialized feed-distribution network was designed to achieve the required excitation amplitude and phase for each stacked-patch element.

Design and Realization of a Planar Ultrawideband Antenna with Notch Band at 3.5 GHz

PubMed Central

2014-01-01

A small antenna with single notch band at 3.5 GHz is designed for ultrawideband (UWB) communication applications. The fabricated antenna comprises a radiating monopole element and a perfectly conducting ground plane with a wide slot. To achieve a notch band at 3.5 GHz, a parasitic element has been inserted in the same plane of the substrate along with the radiating patch. Experimental results shows that, by properly adjusting the position of the parasitic element, the designed antenna can achieve an ultrawide operating band of 3.04 to 11 GHz with a notched band operating at 3.31–3.84 GHz. Moreover, the proposed antenna achieved a good gain except at the notched band and exhibits symmetric radiation patterns throughout the operating band. The prototype of the proposed antenna possesses a very compact size and uses simple structures to attain the stop band characteristic with an aim to lessen the interference between UWB and worldwide interoperability for microwave access (WiMAX) band. PMID:25133245

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.

Next Generation of Magneto-Dielectric Antennas and Optimum Flux Channels

NASA Astrophysics Data System (ADS)

Yousefi, Tara

There is an ever-growing need for broadband conformal antennas to not only reduce the number of antennas utilized to cover a broad range of frequencies (VHF-UHF) but also to reduce visual and RF signatures associated with communication systems. In many applications antennas needs to be very close to low-impedance mediums or embedded inside low-impedance mediums. However, for conventional metal and dielectric antennas to operate efficiently in such environments either a very narrow bandwidth must be tolerated, or enough loss added to expand the bandwidth, or they must be placed one quarter of a wavelength above the conducting surface. The latter is not always possible since in the HF through low UHF bands, critical to Military and Security functions, this quarter-wavelength requirement would result in impractically large antennas. Despite an error based on a false assumption in the 1950’s, which had severely underestimated the efficiency of magneto-dielectric antennas, recently demonstrated magnetic-antennas have been shown to exhibit extraordinary efficiency in conformal applications. Whereas conventional metal-and-dielectric antennas carrying radiating electric currents suffer a significant disadvantage when placed conformal to the conducting surface of a platform, because they induce opposing image currents in the surface, magnetic-antennas carrying magnetic radiating currents have no such limitation. Their magnetic currents produce co-linear image currents in electrically conducting surfaces. However, the permeable antennas built to date have not yet attained the wide bandwidth expected because the magnetic-flux-channels carrying the wave have not been designed to guide the wave near the speed of light at all frequencies. Instead, they tend to lose the wave by a leaky fast-wave mechanism at low frequencies or they over-bind a slow-wave at high frequencies. In this dissertation, we have studied magnetic antennas in detail and presented the design approach and apparatus required to implement a flux-channel carrying the magnetic current wave near the speed of light over a very broad frequency range which also makes the design of a frequency independent antenna (spiral) possible. We will learn how to construct extremely thin conformal antennas, frequency-independent permeable antennas, and even micron-sized antennas that can be embedded inside the brain without damaging the tissue.

Design and adaptation of a folded split ring resonator antenna for use in an animal-borne sensor

NASA Astrophysics Data System (ADS)

Dodson, S. C.; Wiid, P. G.; Niesler, T. R.

2018-03-01

We present the design, optimisation and practical evaluation of a folded split ring resonator (FSRR) antenna for the purpose of radio communication with an animal-borne sensor. We show that the measurements agree with the simulated results and that we are able to produce an electrically small antenna with low mismatch, high radiation efficiency and a quasi-isotropic radiation pattern. We then adapt the topology of the design from a circular to a rectangular shape, to completely fit inside the sensor enclosure. A quasi-isotropic pattern is maintained as well as low mismatch by appropriate tuning. There is a decrease in radiation efficiency which may be countered by a thinner substrate and retuning. We conclude that the adapted FSRR antenna is a suitable design for our application.

Feasibility of Bluetooth Data as a Surrogate Measure of Vehicle Operations

DOT National Transportation Integrated Search

2012-10-01

This research was designed as proof-of-concept study to investigate how Bluetooth data loggers can be used to collect vehicle : operational data over traditional vehicle counting methods. The reliability test included mapping areas for five antenna o...

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.

Compact, low profile antennas for MSAT and mini-M and Std-M land mobile satellite communications

NASA Technical Reports Server (NTRS)

Strickland, P. C.

1995-01-01

CAL Corporation has developed a new class of low profile radiating elements for use in planar phased array antennas. These new elements have been used in the design of a low cost, compact, low profile antenna unit for MSAT and INMARSAT Mini-M land mobile satellite communications. The antenna unit which measures roughly 32 cm in diameter by 5 cm deep incorporates a compact LNA and diplexer unit as well as a complete, low cost, beam steering system. CAL has also developed a low profile antenna unit for INMARSAT-M land mobile satellite communications. A number of these units, which utilize a microstrip patch array design, were put into service in 1994.

K-space polarimetry of bullseye plasmon antennas

PubMed Central

Osorio, Clara I.; Mohtashami, Abbas; Koenderink, A. Femius

2015-01-01

Surface plasmon resonators can drastically redistribute incident light over different output wave vectors and polarizations. This can lead for instance to sub-diffraction sized nanoapertures in metal films that beam and to nanoparticle antennas that enable efficient conversion of photons between spatial modes, or helicity channels. We present a polarimetric Fourier microscope as a new experimental tool to completely characterize the angle-dependent polarization-resolved scattering of single nanostructures. Polarimetry allows determining the full Stokes parameters from just six Fourier images. The degree of polarization and the polarization ellipse are measured for each scattering direction collected by a high NA objective. We showcase the method on plasmonic bullseye antennas in a metal film, which are known to beam light efficiently. We find rich results for the polarization state of the beamed light, including complete conversion of input polarization from linear to circular and from one helicity to another. In addition to uncovering new physics for plasmonic groove antennas, the described technique projects to have a large impact in nanophotonics, in particular towards the investigation of a broad range of phenomena ranging from photon spin Hall effects, polarization to orbital angular momentum transfer and design of plasmon antennas. PMID:25927570

K-space polarimetry of bullseye plasmon antennas.

PubMed

Osorio, Clara I; Mohtashami, Abbas; Koenderink, A Femius

2015-04-30

Surface plasmon resonators can drastically redistribute incident light over different output wave vectors and polarizations. This can lead for instance to sub-diffraction sized nanoapertures in metal films that beam and to nanoparticle antennas that enable efficient conversion of photons between spatial modes, or helicity channels. We present a polarimetric Fourier microscope as a new experimental tool to completely characterize the angle-dependent polarization-resolved scattering of single nanostructures. Polarimetry allows determining the full Stokes parameters from just six Fourier images. The degree of polarization and the polarization ellipse are measured for each scattering direction collected by a high NA objective. We showcase the method on plasmonic bullseye antennas in a metal film, which are known to beam light efficiently. We find rich results for the polarization state of the beamed light, including complete conversion of input polarization from linear to circular and from one helicity to another. In addition to uncovering new physics for plasmonic groove antennas, the described technique projects to have a large impact in nanophotonics, in particular towards the investigation of a broad range of phenomena ranging from photon spin Hall effects, polarization to orbital angular momentum transfer and design of plasmon antennas.

Frequency Domain Beamforming for a Deep Space Network Downlink Array

NASA Technical Reports Server (NTRS)

Navarro, Robert

2012-01-01

This paper describes a frequency domain beamformer to array up to 8 antennas of NASA's Deep Space Network currently in development. The objective of this array is to replace and enhance the capability of the DSN 70m antennas with multiple 34m antennas for telemetry, navigation and radio science use. The array will coherently combine the entire 500 MHz of usable bandwidth available to DSN receivers. A frequency domain beamforming architecture was chosen over a time domain based architecture to handle the large signal bandwidth and efficiently perform delay and phase calibration. The antennas of the DSN are spaced far enough apart that random atmospheric and phase variations between antennas need to be calibrated out on an ongoing basis in real-time. The calibration is done using measurements obtained from a correlator. This DSN Downlink Array expands upon a proof of concept breadboard array built previously to develop the technology and will become an operational asset of the Deep Space Network. Design parameters for frequency channelization, array calibration and delay corrections will be presented as well a method to efficiently calibrate the array for both wide and narrow bandwidth telemetry.

Performance of a Wideband Cadmium Ferrite Microstrip Patch Antenna in the X-Band Region

NASA Astrophysics Data System (ADS)

Bhongale, S. R.; Ingavale, H. R.; Shinde, T. J.; Vasambekar, P. N.

2018-01-01

Magnesium-substituted cadmium ferrites with the chemical composition Mg x Cd1- x Fe2O4 ( x = 0, 0.4 and 0.8) were prepared by an oxalate co-precipitation method under microwave sintering technique. The structural properties of ferrites were studied by x-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscope techniques. The scattering parameters such as reflection coefficient ( S 11) and transmission coefficient ( S 21) at microwave frequencies of palletized ferrites were measured by using a vector network analyzer. The software module 85071E followed by scattering parameters was used to determine the electromagnetic properties of the ferrites. The values determined for electromagnetic parameters such as the real part of permittivity ( ɛ'), permeability ( μ'), dielectric loss tangent (tan δ e) and magnetic loss tangent (tan δ m) of synthesized ferrites were used to design rectangular microstrip patch antennas. The performance of magnesium-substituted Cd ferrites as substrate for microstrip patch antennas was investigated. The antenna parameters such as return loss, bandwidth, voltage standing wave ratio, Smith chart and radiation pattern were studied. It is found that the Cd ferrite has applicability as a substrate for wideband antennas in the X-band region.

Modeling startup and shutdown transient of the microlinear piezo drive via ANSYS

NASA Astrophysics Data System (ADS)

Azin, A. V.; Bogdanov, E. P.; Rikkonen, S. V.; Ponomarev, S. V.; Khramtsov, A. M.

2017-02-01

The article describes the construction-design of the micro linear piezo drive intended for a peripheral cord tensioner in the reflecting surface shape regulator system for large-sized transformable spacecraft antenna reflectors. The research target -the development method of modeling startup and shutdown transient of the micro linear piezo drive. This method is based on application software package ANSYS. The method embraces a detailed description of the calculation stages to determine the operating characteristics of the designed piezo drive. Based on the numerical solutions, the time characteristics of the designed piezo drive are determined.

Integrated Lens Antennas for Multi-Pixel Receivers

NASA Technical Reports Server (NTRS)

Lee, Choonsup; Chattopadhyay, Goutam

2011-01-01

Future astrophysics and planetary experiments are expected to require large focal plane arrays with thousands of detectors. Feedhorns have excellent performance, but their mass, size, fabrication challenges, and expense become prohibitive for very large focal plane arrays. Most planar antenna designs produce broad beam patterns, and therefore require additional elements for efficient coupling to the telescope optics, such as substrate lenses or micromachined horns. An antenna array with integrated silicon microlenses that can be fabricated photolithographically effectively addresses these issues. This approach eliminates manual assembly of arrays of lenses and reduces assembly errors and tolerances. Moreover, an antenna array without metallic horns will reduce mass of any planetary instrument significantly. The design has a monolithic array of lens-coupled, leaky-wave antennas operating in the millimeter- and submillimeter-wave frequencies. Electromagnetic simulations show that the electromagnetic fields in such lens-coupled antennas are mostly confined in approximately 12 15 . This means that one needs to design a small-angle sector lens that is much easier to fabricate using standard lithographic techniques, instead of a full hyper-hemispherical lens. Moreover, this small-angle sector lens can be easily integrated with the antennas in an array for multi-pixel imager and receiver implementation. The leaky antenna is designed using double-slot irises and fed with TE10 waveguide mode. The lens implementation starts with a silicon substrate. Photoresist with appropriate thickness (optimized for the lens size) is spun on the substrate and then reflowed to get the desired lens structure. An antenna array integrated with individual lenses for higher directivity and excellent beam profile will go a long way in realizing multi-pixel arrays and imagers. This technology will enable a new generation of compact, low-mass, and highly efficient antenna arrays for use in multi-pixel receivers and imagers for future planetary and astronomical instruments. These antenna arrays can also be used in radars and imagers for contraband detection at stand-off distances. This will be enabling technology for future balloon-borne, smaller explorer class mission (SMEX), and other missions, and for a wide range of proposed planetary sounders and radars for planetary bodies.

Solar Power Satellite (SPS) solid-state antenna power combiner

NASA Technical Reports Server (NTRS)

1980-01-01

A low loss power-combining microstrip antenna suitable for solid state solar power satellite (SPS) application was developed. A unique approach for performing both the combining and radiating function in a single cavity-type circuit was verified, representing substantial refinements over previous demonstration models in terms of detailed geometry to obtain good matching and adequate bandwidth at the design frequency. The combiner circuit was designed, built, and tested and the overall results support the view that the solid state power-combining antenna approach is a viable candidate for a solid state SPS antenna building block.

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.

A corner-reflector mixer mount for far infrared wavelengths.

PubMed

Zmuidzinas, J; Betz, A L; Boreiko, R T

1989-01-01

A new type of corner-reflector mixer mount, which has the advantages of ease of fabrication and assembly as well as frequency versatility, has been designed and constructed. The mixer works with arbitrary antenna lengths > or = 4 lambda with the reflector to antenna spacing adjusted to give a strong and symmetric central lobe. The predicted response patterns have been experimentally verified for various antenna lengths and operating frequencies between 800 and 2000 GHz. An important design feature is the incorporation of a microstrip matching network which eliminates IF impedance mismatch and provides mechanical isolation of the whisker antenna.

Dielectric resonator antenna for coupling to NV centers in diamond

NASA Astrophysics Data System (ADS)

Kapitanova, Polina; Soshenko, Vladimir; Vorobyov, Vadim; Dobrykh, Dmitry; Bolshedvorskiih, Stepan; Sorokin, Vadim; Akimov, Alexey

2017-09-01

Here we present the design of a dielectric resonator antenna for spin manipulation of large volume ensemble of nitrogen-vacancy centers in a bulk diamond. The proposed antenna design is based on a high permittivity hollow dielectric resonator excited by a symmetric microstrip loop. We present the result of numerical simulation of the magnetic field excited at the TE01δ mode of the dielectric resonator. We analyze the uniformity of the magnetic field in volume and discuss the possibility to use the antenna for efficient excitation of nitrogen-vacancy centers in whole commercially available sample.

High Gain Antenna Gimbal for the 2003-2004 Mars Exploration Rover Program

NASA Technical Reports Server (NTRS)

Sokol, Jeff; Krishnan, Satish; Ayari, Laoucet

2004-01-01

The High Gain Antenna Assemblies built for the 2003-2004 Mars Exploration Rover (MER) missions provide the primary communication link for the Rovers once they arrive on Mars. The High Gain Antenna Gimbal (HGAG) portion of the assembly is a two-axis gimbal that provides the structural support, pointing, and tracking for the High Gain Antenna (HGA). The MER mission requirements provided some unique design challenges for the HGAG. This paper describes all the major subsystems of the HGAG that were developed to meet these challenges, and the requirements that drove their design.

Polarizability tensor retrieval for magnetic and plasmonic antenna design

NASA Astrophysics Data System (ADS)

Bernal Arango, Felipe; Femius Koenderink, A.

2013-07-01

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

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

Microstrip patch antenna receiving array operating in the Ku band

NASA Technical Reports Server (NTRS)

Walcher, Douglas A.

1996-01-01

Microstrip patch antennas were first investigated from the idea that it would be highly advantageous to fabricate radiating elements (antennas) on the same dielectric substrate as RF circuitry and transmission lines. Other advantages were soon discovered to be its lightweight, low profile, conformability to shaped surfaces, and low manufacturing costs. Unfortunately, these same patches continually exhibit narrow bandwidths, wide beamwidths, and low antenna gain. This thesis will present the design and experimental results of a microstrip patch antenna receiving array operating in the Ku band. An antenna array will be designed in an attempt to improve its performance over a single patch. Most Ku band information signals are either wide band television images or narrow band data and voice channels. An attempt to improve the gain of the array by introducing parasitic patches on top of the array will also be presented in this thesis.

Robustness of plasmon phased array nanoantennas to disorder

PubMed Central

Arango, Felipe Bernal; Thijssen, Rutger; Brenny, Benjamin; Coenen, Toon; Koenderink, A. Femius

2015-01-01

We present cathodoluminescence experiments that quantify the response of plasmonic Yagi-Uda antennas fabricated on one-dimensional silicon nitride waveguides as function of electron beam excitation position and emission wavelength. At the near-infrared antenna design wavelength cathodoluminescence signal robustly is strongest when exciting the antenna at the reflector element. Yet at just slightly shorter wavelengths the signal is highly variable from antenna to antenna and wavelength to wavelength. Hypothesizing that fabrication randomness is at play, we analyze the resilience of plasmon Yagi-Uda antennas to varations in element size of just 5 nm. While in our calculations the appearance of directivity is robust, both the obtained highest directivity and the wavelength at which it occurs vary markedly between realizations. The calculated local density of states is invariably high at the reflector for the design wavelength, but varies dramatically in spatial distribution for shorter wavelengths, consistent with the cathodoluminescence experiments. PMID:26038871

Dual-polarized feed antenna apparatus and method of use

NASA Technical Reports Server (NTRS)

Sarehraz, Mohammed (Inventor); Buckle, Kenneth A. (Inventor); Stefanakos, Elias (Inventor); Weller, Thomas (Inventor); Goswami, D. Yogi (Inventor)

2009-01-01

An antenna apparatus and method for the interception of randomly polarized electromagnetic waves utilizing a dual polarized antenna which is excited through a cross-slot aperture using two well-isolated orthogonal feeds.

Dual-polarized feed antenna apparatus and method of use

NASA Technical Reports Server (NTRS)

Sarehraz, Mohammad (Inventor); Buckle, Kenneth A. (Inventor); Stefanakos, Elias (Inventor); Weller, Thomas (Inventor); Goswami, D. Yogi (Inventor)

2008-01-01

An antenna apparatus and method for the interception of randomly polarized electromagnetic waves utilizing a dual polarized antenna which is excited through a cross-slot aperture using two well-isolated orthogonal feeds.

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

NASA Astrophysics Data System (ADS)

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

2006-07-01

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

Scheduling and Topology Design in Networks with Directional Antennas

DTIC Science & Technology

2017-05-19

emergency response networks was recently studied in [14] and [15]. This work examines the topology control problem in group - based wireless networks that...Broadcast Fig. 7: Max-min throughput ⇢ versus number of nodes for non -uniform edge capacities [14] T. Suzuki, et al. “Directional Antenna Control based...Scheduling and Topology Design in Networks with Directional Antennas Thomas Stahlbuhk, Nathaniel M. Jones, Brooke Shrader Lincoln Laboratory

Electromagnetic Modeling, Optimization and Uncertainty Quantification for Antenna and Radar Systems Surfaces Scattering and Energy Absorption

DTIC Science & Technology

2017-03-06

design of antenna and radar systems, energy absorption and scattering by rough-surfaces. This work has lead to significant new methodologies , including...problems in the field of electromagnetic propagation and scattering, with applicability to design of antenna and radar systems, energy absorption...and scattering by rough-surfaces. This work has lead to significant new methodologies , including introduction of a certain Windowed Green Function

On the cross-polarization characteristics of crooked wire antennas designed by genetic-algorithms

NASA Technical Reports Server (NTRS)

Rengarajan, S. R.; Rahmat-Samii, Y.

2002-01-01

In many modern communication applications there is a need for simple circularly polarized antennas for hemispherical coverage with good axial ratio or low value of cross polarization. We revisited the crooked wire antenna because of its simplicity. This paper presents results of our investigation on the crooked wire antennas and other elements.

Method of steering the gain of a multiple antenna global positioning system receiver

NASA Astrophysics Data System (ADS)

Evans, Alan G.; Hermann, Bruce R.

1992-06-01

A method for steering the gain of a multiple antenna Global Positioning System (GPS) receiver toward a plurality of a GPS satellites simultaneously is provided. The GPS signals of a known wavelength are processed digitally for a particular instant in time. A range difference or propagation delay between each antenna for GPS signals received from each satellite is first resolved. The range difference consists of a fractional wavelength difference and an integer wavelength difference. The fractional wavelength difference is determined by each antenna's tracking loop. The integer wavelength difference is based upon the known wavelength and separation between each antenna with respect to each satellite position. The range difference is then used to digitally delay the GPS signals at each antenna with respect to a reference antenna. The signal at the reference antenna is then summed with the digitally delayed signals to generate a composite antenna gain. The method searches for the correct number of integer wavelengths to maximize the composite gain. The range differences are also used to determine the attitude of the array.

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.

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.

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.

Short Wave Direction Finders

DTIC Science & Technology

1960-05-23

or designing direction finders. In CIApter 1, written by candidate of technical sciences, lec- turer O.V.Belavin, are considered direction finding...direction finding methods. In the design of radio direction finders with long base, qustioons arise of the advantageous choice of an antenna system, of the...dieeoticfindors, and reoommadat4ons on the design of radio direetion finders from the point of view of reduting the asaratu errors. og-’eae re~.o dkitctlon

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.

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

Multi-Step Ka/Ka Dichroic Plate with Rounded Corners for NASA's 34m Beam Waveguide Antenna

NASA Technical Reports Server (NTRS)

Veruttipong, Watt; Khayatian, Behrouz; Hoppe, Daniel; Long, Ezra

2013-01-01

A multi-step Ka/Ka dichroic plate Frequency Selective Surface (FSS structure) is designed, manufactured and tested for use in NASA's Deep Space Network (DSN) 34m Beam Waveguide (BWG) antennas. The proposed design allows ease of manufacturing and ability to handle the increased transmit power (reflected off the FSS) of the DSN BWG antennas from 20kW to 100 kW. The dichroic is designed using HFSS and results agree well with measured data considering the manufacturing tolerances that could be achieved on the dichroic.

New 2D diffraction model and its applications to terahertz parallel-plate waveguide power splitters

PubMed Central

Zhang, Fan; Song, Kaijun; Fan, Yong

2017-01-01

A two-dimensional (2D) diffraction model for the calculation of the diffraction field in 2D space and its applications to terahertz parallel-plate waveguide power splitters are proposed in this paper. Compared with the Huygens-Fresnel principle in three-dimensional (3D) space, the proposed model provides an approximate analytical expression to calculate the diffraction field in 2D space. The diffraction filed is regarded as the superposition integral in 2D space. The calculated results obtained from the proposed diffraction model agree well with the ones by software HFSS based on the element method (FEM). Based on the proposed 2D diffraction model, two parallel-plate waveguide power splitters are presented. The splitters consist of a transmitting horn antenna, reflectors, and a receiving antenna array. The reflector is cylindrical parabolic with superimposed surface relief to efficiently couple the transmitted wave into the receiving antenna array. The reflector is applied as computer-generated holograms to match the transformed field to the receiving antenna aperture field. The power splitters were optimized by a modified real-coded genetic algorithm. The computed results of the splitters agreed well with the ones obtained by software HFSS verify the novel design method for power splitter, which shows good applied prospects of the proposed 2D diffraction model. PMID:28181514

Arm Locking for the Laser Interferometer Space Antenna

NASA Technical Reports Server (NTRS)

Maghami, P. G.; Thorpe, J. I.; Livas, J.

2009-01-01

The Laser Interferometer Space Antenna (LISA) mission is a planned gravitational wave detector consisting of three spacecraft in heliocentric orbit. Laser interferometry is used to measure distance fluctuations between test masses aboard each spacecraft to the picometer level over a 5 million kilometer separation. Laser frequency fluctuations must be suppressed in order to meet the measurement requirements. Arm-locking, a technique that uses the constellation of spacecraft as a frequency reference, is a proposed method for stabilizing the laser frequency. We consider the problem of arm-locking using classical optimal control theory and find that our designs satisfy the LISA requirements.

Feasibility and systems definition study for microwave multi-application payload (MMAP)

NASA Technical Reports Server (NTRS)

Horton, J. B.; Allen, C. C.; Massaro, M. J.; Zemany, J. L.; Murrell, J. W.; Stanhouse, R. W.; Condon, G. P.; Stone, R. F.

1977-01-01

There were three Shuttle/Spacelab experiments: adaptive multibeam phased array antenna (AMPA) experiment, electromagnetic environment experiment (EEE), and millimeter wave communications experiment (MWCE). Work on the AMPA experiment was completed. Results included are definition of operating modes, sequence of operation, radii of operation about several ground stations, signal format, foot prints of typical orbits and preliminary definition of ground and user terminals. Definition of the MOD I EEE included conceptual hardware designs, spacelab interfaces, preliminary data handling methods, experiment tests and verification, and EMC studies. The MWCE was defined conceptually for a steerable high gain antenna.

Illusion optics: Optically transforming the nature and the location of electromagnetic emissions

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

Yi, Jianjia; Tichit, Paul-Henri; Burokur, Shah Nawaz, E-mail: shah-nawaz.burokur@u-psud.fr

Complex electromagnetic structures can be designed by using the powerful concept of transformation electromagnetics. In this study, we define a spatial coordinate transformation that shows the possibility of designing a device capable of producing an illusion on an antenna radiation pattern. Indeed, by compressing the space containing a radiating element, we show that it is able to change the radiation pattern and to make the radiation location appear outside the latter space. Both continuous and discretized models with calculated electromagnetic parameter values are presented. A reduction of the electromagnetic material parameters is also proposed for a possible physical fabrication ofmore » the device with achievable values of permittivity and permeability that can be obtained from existing well-known metamaterials. Following that, the design of the proposed antenna using a layered metamaterial is presented. Full wave numerical simulations using Finite Element Method are performed to demonstrate the performances of such a device.« less

Planar Submillimeter-Wave Mixer Technology with Integrated Antenna

NASA Technical Reports Server (NTRS)

Chattopadhyay, Gautam; Mehdi, Imran; Gill, John J.; Lee, Choonsup; lombart, Muria L.; Thomas, Betrand

2010-01-01

High-performance mixers at terahertz frequencies require good matching between the coupling circuits such as antennas and local oscillators and the diode embedding impedance. With the availability of amplifiers at submillimeter wavelengths and the need to have multi-pixel imagers and cameras, planar mixer architecture is required to have an integrated system. An integrated mixer with planar antenna provides a compact and optimized design at terahertz frequencies. Moreover, it leads to a planar architecture that enables efficient interconnect with submillimeter-wave amplifiers. In this architecture, a planar slot antenna is designed on a thin gallium arsenide (GaAs) membrane in such a way that the beam on either side of the membrane is symmetric and has good beam profile with high coupling efficiency. A coplanar waveguide (CPW) coupled Schottky diode mixer is designed and integrated with the antenna. In this architecture, the local oscillator (LO) is coupled through one side of the antenna and the RF from the other side, without requiring any beam sp litters or diplexers. The intermediate frequency (IF) comes out on a 50-ohm CPW line at the edge of the mixer chip, which can be wire-bonded to external circuits. This unique terahertz mixer has an integrated single planar antenna for coupling both the radio frequency (RF) input and LO injection without any diplexer or beamsplitters. The design utilizes novel planar slot antenna architecture on a 3- mthick GaAs membrane. This work is required to enable future multi-pixel terahertz receivers for astrophysics missions, and lightweight and compact receivers for planetary missions to the outer planets in our solar system. Also, this technology can be used in tera hertz radar imaging applications as well as for testing of quantum cascade lasers (QCLs).

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.

Deep Space Network Antenna Monitoring Using Adaptive Time Series Methods and Hidden Markov Models

NASA Technical Reports Server (NTRS)

Smyth, Padhraic; Mellstrom, Jeff

1993-01-01

The Deep Space Network (DSN)(designed and operated by the Jet Propulsion Laboratory for the National Aeronautics and Space Administration (NASA) provides end-to-end telecommunication capabilities between earth and various interplanetary spacecraft throughout the solar system.

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.

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.

Antennas for 20/30 GHz and beyond

NASA Technical Reports Server (NTRS)

Chen, C. Harry; Wong, William C.; Hamada, S. Jim

1989-01-01

Antennas of 20/30 GHz and higher frequency, due to the small wavelength, offer capabilities for many space applications. With the government-sponsored space programs (such as ACTS) in recent years, the industry has gone through the learning curve of designing and developing high-performance, multi-function antennas in this frequency range. Design and analysis tools (such as the computer modelling used in feedhorn design and reflector surface and thermal distortion analysis) are available. The components/devices (such as BFN's, weight modules, feedhorns and etc.) are space-qualified. The manufacturing procedures (such as reflector surface control) are refined to meet the stringent tolerance accompanying high frequencies. The integration and testing facilities (such as Near-Field range) also advance to facilitate precision assembling and performance verification. These capabilities, essential to the successful design and development of high-frequency spaceborne antennas, shall find more space applications (such as ESGP) than just communications.

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

NASA Astrophysics Data System (ADS)

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

2015-02-01

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

High Dielectric Low Loss Transparent Glass Material Based Dielectric Resonator Antenna with Wide Bandwidth Operation

NASA Astrophysics Data System (ADS)

Mehmood, Arshad; Zheng, Yuliang; Braun, Hubertus; Hovhannisyan, Martun; Letz, Martin; Jakoby, Rolf

2015-01-01

This paper presents the application of new high permittivity and low loss glass material for antennas. This glass material is transparent. A very simple rectangular dielectric resonator antenna is designed first with a simple microstrip feeding line. In order to widen the bandwidth, the feed of the design is modified by forming a T-shaped feeding. This new design enhanced the bandwidth range to cover the WLAN 5 GHz band completely. The dielectric resonator antenna cut into precise dimensions is placed on the modified microstrip feed line. The design is simple and easy to manufacture and also very compact in size of only 36 × 28 mm. A -10 dB impedance bandwidth of 18% has been achieved, which covers the frequency range from 5.15 GHz to 5.95 GHz. Simulations of the measured return loss and radiation patterns are presented and discussed.

Studies of RF sheaths and diagnostics on IShTAR

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

Crombé, K., E-mail: Kristel.Crombe@UGent.be; LPP-ERM/KMS, Royal Military Academy, Brussels; Devaux, S.

2015-12-10

IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetised plasma test facility for RF sheaths studies at the Max-Planck-Institut für Plasmaphysik in Garching. In contrast to a tokamak, a test stand provides more liberty to impose the parameters and gives better access for the instrumentation and antennas. The project will support the development of diagnostic methods for characterising RF sheaths and validate and improve theoretical predictions. The cylindrical vacuum vessel has a diameter of 1 m and is 1.1 m long. The plasma is created by an external cylindrical plasma source equipped with a helical antenna that has been designed tomore » excite the m=1 helicon mode. In inductive mode, plasma densities and electron temperatures have been characterised with a planar Langmuir probe as a function of gas pressure and input RF power. A 2D array of RF compensated Langmuir probes and a spectrometer are planned. A single strap RF antenna has been designed; the plasma-facing surface is aligned to the cylindrical plasma to ease the modelling. The probes will allow direct measurements of plasma density profiles in front of the RF antenna, and thus a detailed study of the density modifications induced by RF sheaths, which influences the coupling. The RF antenna frequency has been chosen to study different plasma wave interactions: the accessible plasma density range includes an evanescent and propagative behaviour of slow or fast waves, and allows the study of the effect of the lower hybrid resonance layer.« less

An ultra-wideband antenna for pulsed applications

NASA Technical Reports Server (NTRS)

Darden, William H.; Burnside, Walter D.; Gilreath, Melvin C.

1993-01-01

A wideband feed is proposed to support wideband radiation, and a design process is presented for a slotline bowtie hybrid (SBH) antenna based on specified pattern characteristics. Measured results are presented to demonstrate the pattern control of the antenna over its bandwidth. Impulse response plots are used to illustrate the pulse performance of this antenna type. For the antenna discussed here, the bandwidth was measured to be 6 to 1 and actually is expected to be larger.

Hyperbola-parabola primary mirror in Cassegrain optical antenna to improve transmission efficiency.

PubMed

Zhang, Li; Chen, Lu; Yang, HuaJun; Jiang, Ping; Mao, Shengqian; Caiyang, Weinan

2015-08-20

An optical model with a hyperbola-parabola primary mirror added in the Cassegrain optical antenna, which can effectively improve the transmission efficiency, is proposed in this paper. The optimum parameters of a hyperbola-parabola primary mirror and a secondary mirror for the optical antenna system have been designed and analyzed in detail. The parabola-hyperbola primary structure optical antenna is obtained to improve the transmission efficiency of 10.60% in theory, and the simulation efficiency changed 9.359%. For different deflection angles to the receiving antenna with the emit antenna, the coupling efficiency curve of the optical antenna has been obtained.

Task three: Report: STDN Antenna and preamplifier cost tradeoff study. [combinations of antennas and preamplifiers for several communication environments

NASA Technical Reports Server (NTRS)

1973-01-01

The general goal of this task, STDN Antenna and Preamplifier G/T Study, was to determine cost-effective combinations of antennas and preamplifiers for several sets of conditions for frequency, antenna elevation angle, and rain. The output of the study includes design curves and tables which indicate the best choice of antenna size and preamplifier type to provide a given G/T performance. The report indicates how to evaluate the cost effectiveness of proposed improvements to a given station. Certain parametric variations are presented to emphasize the improvement available by reducing RF losses and improving the antenna feed.

Electromagnetic Performances Analysis of an Ultra-wideband and Flexible Material Antenna in Microwave Breast Imaging: To Implement A Wearable Medical Bra.

PubMed

Rahman, Ashiqur; Islam, Mohammad Tariqul; Singh, Mandeep Jit; Kibria, Salehin; Akhtaruzzaman, Md

2016-12-23

In this paper, we report a compact and ultra-wide band antenna on a flexible substrate using the 5-(4-(perfluorohexyl)phenyl)thiophene-2-carbaldehyde compound for microwave imaging. In contrast to other microwave based imaging systems, such as an array of 16 antennas, we proposed a bi-static radar based imaging system consisting of two omnidirectional antennas, which reduces complexity and the overall dimension. The proposed compact antennas are 20 × 14 mm 2 and designed for operating at frequencies from 4 to 6 GHz. To allow for implantation into a bra, the electromagnetic performances of the antennas must be considered in bending conditions. In comparison with the recently reported flexible antennas, we demonstrated both electromagnetic performance and imaging reconstruction for bending conditions. For the proof of concept, the electromagnetic performances both at flat and bending conditions have been verified using a homogeneous multilayer model of the human breast phantom. Our results demonstrate that the antenna, even at bending conditions, exhibits an excellent omni-directional radiation pattern with an average efficiency above 70% and average gain above 1 dBi, within the operational frequency band. The comprehensive aim of the realized antenna is to design a biodegradable and wearable antenna-based bra for early breast cancer detection in the future.

Electromagnetic Performances Analysis of an Ultra-wideband and Flexible Material Antenna in Microwave Breast Imaging: To Implement A Wearable Medical Bra

NASA Astrophysics Data System (ADS)

Rahman, Ashiqur; Islam, Mohammad Tariqul; Singh, Mandeep Jit; Kibria, Salehin; Akhtaruzzaman, Md.

2016-12-01

In this paper, we report a compact and ultra-wide band antenna on a flexible substrate using the 5-(4-(perfluorohexyl)phenyl)thiophene-2-carbaldehyde compound for microwave imaging. In contrast to other microwave based imaging systems, such as an array of 16 antennas, we proposed a bi-static radar based imaging system consisting of two omnidirectional antennas, which reduces complexity and the overall dimension. The proposed compact antennas are 20 × 14 mm2 and designed for operating at frequencies from 4 to 6 GHz. To allow for implantation into a bra, the electromagnetic performances of the antennas must be considered in bending conditions. In comparison with the recently reported flexible antennas, we demonstrated both electromagnetic performance and imaging reconstruction for bending conditions. For the proof of concept, the electromagnetic performances both at flat and bending conditions have been verified using a homogeneous multilayer model of the human breast phantom. Our results demonstrate that the antenna, even at bending conditions, exhibits an excellent omni-directional radiation pattern with an average efficiency above 70% and average gain above 1 dBi, within the operational frequency band. The comprehensive aim of the realized antenna is to design a biodegradable and wearable antenna-based bra for early breast cancer detection in the future.

Design and Simulation of Horn Antenna Using CST Software for GPR System

NASA Astrophysics Data System (ADS)

Joret, Ariffuddin; Sulong, M. S.; Abdullah, M. F. L.; Madun, Aziman; Haimi Dahlan, Samsul

2018-04-01

Detection of underground object can be made using a GPR system. This system is classified as a non-destructive technique (NDT) where the ground areas need not to be excavated. The technique used by the GPR system is by measuring the reflection of electromagnetic wave signal produced and detected by antenna which is known as the transmitter and the receiver antenna. In this study, a GPR system was studied by means of simulation using a Horn antenna as a transceiver antenna. The electromagnetic wave signal in this simulation is produced by current signal of an antenna which having a shape of modulation of Gaussian pulse which is having spectrum from 8 GHz until 12 GHz. CST and MATLAB Software are used in this GPR system simulation. A model of a Horn antenna has been designed using the CST software before the GPR’s system simulation modeled by adding a model of background in front of the Horn antenna. The simulation results show that the output signal of the Horn antenna can be used in detecting embedded object which are made from material of wood and iron. In addition, the simulation result has successfully developed a 3D model image of the GPR system using output signal of the Horn antenna. The embedded iron object in the GPR system simulation can be seen clearly by using this 3D image.

Method and apparatus for reliable inter-antenna baseline determination

NASA Technical Reports Server (NTRS)

Wilson, John M. (Inventor)

2001-01-01

Disclosed is a method for inter-antenna baseline determination that uses an antenna configuration comprising a pair of relatively closely spaced antennas and other pairs of distant antennas. The closely spaced pair provides a short baseline having an integer ambiguity that may be searched exhaustively to identify the correct set of integers. This baseline is then used as a priori information to aid the determination of longer baselines that, once determined, may be used for accurate run time attitude determination.

Tissue Variability and Antennas for Power Transfer to Wireless Implantable Medical Devices.

PubMed

Bocan, Kara N; Mickle, Marlin H; Sejdic, Ervin

2017-01-01

The design of effective transcutaneous systems demands the consideration of inevitable variations in tissue characteristics, which vary across body areas, among individuals, and over time. The purpose of this paper was to design and evaluate several printed antenna topologies for ultrahigh frequency (UHF) transcutaneous power transfer to implantable medical devices, and to investigate the effects of variations in tissue properties on dipole and loop topologies. Here, we show that a loop antenna topology provides the greatest achievable gain with the smallest implanted antenna, while a dipole system provides higher impedance for conjugate matching and the ability to increase gain with a larger external antenna. In comparison to the dipole system, the loop system exhibits greater sensitivity to changes in tissue structure and properties in terms of power gain, but provides higher gain when the separation is on the order of the smaller antenna dimension. The dipole system was shown to provide higher gain than the loop system at greater implant depths for the same implanted antenna area, and was less sensitive to variations in tissue properties and structure in terms of power gain at all investigated implant depths. The results show the potential of easily-fabricated, low-cost printed antenna topologies for UHF transcutaneous power, and the importance of environmental considerations in choosing the antenna topology.

Tissue Variability and Antennas for Power Transfer to Wireless Implantable Medical Devices

PubMed Central

Bocan, Kara N.; Mickle, Marlin H.

2017-01-01

The design of effective transcutaneous systems demands the consideration of inevitable variations in tissue characteristics, which vary across body areas, among individuals, and over time. The purpose of this paper was to design and evaluate several printed antenna topologies for ultrahigh frequency (UHF) transcutaneous power transfer to implantable medical devices, and to investigate the effects of variations in tissue properties on dipole and loop topologies. Here, we show that a loop antenna topology provides the greatest achievable gain with the smallest implanted antenna, while a dipole system provides higher impedance for conjugate matching and the ability to increase gain with a larger external antenna. In comparison to the dipole system, the loop system exhibits greater sensitivity to changes in tissue structure and properties in terms of power gain, but provides higher gain when the separation is on the order of the smaller antenna dimension. The dipole system was shown to provide higher gain than the loop system at greater implant depths for the same implanted antenna area, and was less sensitive to variations in tissue properties and structure in terms of power gain at all investigated implant depths. The results show the potential of easily-fabricated, low-cost printed antenna topologies for UHF transcutaneous power, and the importance of environmental considerations in choosing the antenna topology. PMID:29018637

Design and characterisation of miniaturised cavity-backed patch antenna for microwave hyperthermia.

PubMed

Chakaravarthi, Geetha; Arunachalam, Kavitha

2015-01-01

The aim of this study was to describe the design and characterisation of a miniaturised 434 MHz patch antenna enclosed in a metal cavity for microwave hyperthermia treatment of cancer. Electromagnetic (EM) field distribution in the near field of a microstrip patch irradiating body tissue was studied using finite element method (FEM) simulations. Antenna miniaturisation was achieved through dielectric loading with very high permittivity, metal enclosure, patch folding and shorting post. Frequency dependent electrical properties of materials were incorporated wherever appropriate using dispersion model and measurements. Antenna return loss and specific absorption rate (SAR) at 434 MHz were measured on muscle phantoms for characterisation. The design was progressively optimised to yield a compact 434 MHz patch (22 mm × 8.8 mm × 10 mm) inside a metal cavity (40 mm × 12 mm) with integrated coupling water bolus (35 mm). The fabricated antenna with integrated water bolus was self resonant at 434 MHz without load, and has better than -10 dB return loss (S11) with 13-20 MHz bandwidth on two different phantoms. SAR at 434 MHz measured using an infrared (IR) thermal camera on split phantoms indicated penetration depth for -3 dB SAR as 8.25 mm compared to 8.87 mm for simulation. The simulated and measured SAR coverage along phantom depth was 3.09 cm(2) and 3.21 cm(2) respectively at -3 dB, and 6.42 cm(2) and 9.07 cm(2) respectively at -6 dB. SAR full width at half maximum (FWHM) at 5 mm and 20 mm depths were 54.68 mm and 51.18 mm respectively in simulation, and 49.47 mm and 43.75 mm respectively in experiments. Performance comparison of the cavity-backed patch indicates more than 89% co-polarisation and higher directivity which resulted in deeper penetration compared to the patch applicators of similar or larger size proposed for hyperthermia treatment of cancer. The fabricated cavity-backed applicator is self-resonant at 434 MHz with a negligible shift in resonance when coupled to different phantoms, Δf/f0 less than 1.16%. IR thermography-based SAR measurements indicated that the -3 dB SAR of the cavity-backed aperture antenna covered the radiating aperture surface at 5 mm and 20 mm depths. It can be concluded that the compact cavity-backed patch antenna has stable resonance, higher directivity and low cross polarisation, and is suitable for design of microwave hyperthermia array applicators with adjustable heating pattern for superficial and/or deep tissue heating.

Wideband QAMC reflector's antenna for low profile applications

NASA Astrophysics Data System (ADS)

Grelier, M.; Jousset, M.; Mallégol, S.; Lepage, A. C.; Begaud, X.; LeMener, J. M.

2011-06-01

A wideband reflector's antenna based on quasi-artificial magnetic conductor is proposed. To validate the design, an Archimedean spiral has been backed to this new reflector. In comparison to classical solution using absorbent material, the prototype presents a very low thickness of λ/15 at the lowest operating frequency and an improved gain over a 2.4:1 bandwidth. The whole methodology to design this reflector can be applied to other wideband antennas.

Design considerations for MST radar antennas

NASA Technical Reports Server (NTRS)

Bowhill, S. A.

1983-01-01

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

Information-Theoretic Limits on Broadband Multi-Antenna Systems in the Presence of Mutual Coupling

NASA Astrophysics Data System (ADS)

Taluja, Pawandeep Singh

2011-12-01

Multiple-input, multiple-output (MIMO) systems have received considerable attention over the last decade due to their ability to provide high throughputs and mitigate multipath fading effects. While most of these benefits are obtained for ideal arrays with large separation between the antennas, practical devices are often constrained in physical dimensions. With smaller inter-element spacings, signal correlation and mutual coupling between the antennas start to degrade the system performance, thereby limiting the deployment of a large number of antennas. Various studies have proposed transceiver designs based on optimal matching networks to compensate for this loss. However, such networks are considered impractical due to their multiport structure and sensitivity to the RF bandwidth of the system. In this dissertation, we investigate two aspects of compact transceiver design. First, we consider simpler architectures that exploit coupling between the antennas, and second, we establish information-theoretic limits of broadband communication systems with closely-spaced antennas. We begin with a receiver model of a diversity antenna selection system and propose novel strategies that make use of inactive elements by virtue of mutual coupling. We then examine the limits on the matching efficiency of a single antenna system using broadband matching theory. Next, we present an extension to this theory for coupled MIMO systems to elucidate the impact of coupling on the RF bandwidth of the system, and derive optimal transceiver designs. Lastly, we summarize the main findings of this dissertation and suggest open problems for future work.

Implementation of rectangular slit-inserted ultra-wideband tapered slot antenna.

PubMed

Kim, Sun-Woong; Choi, Dong-You

2016-01-01

In this paper, a tapered slot antenna capable of ultra-wideband communication was designed. In the proposed antenna, rectangular slits were inserted to enhance the bandwidth and reduce the area of the antenna. The rectangular slit-inserted tapered slot antenna operated at a bandwidth of 8.45 GHz, and the bandwidth improved upon the basic tapered slot antenna by 4.72 GHz. The radiation pattern of the antenna was suitable for location recognition in a certain direction owing to an appropriate 3 dB beam width. The antenna gain was analyzed within the proposed bandwidth, and the highest gain characteristic at 7.55 dBi was exhibited at a 5-GHz band. The simulation and measurement results of the proposed tapered slot antenna were similar.

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

DOE PAGES

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

2016-08-02

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

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

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

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

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

Dual-Vivaldi wideband nanoantenna with high radiation efficiency over the infrared frequency band.

PubMed

Iluz, Zeev; Boag, Amir

2011-08-01

A dual-Vivaldi nanoantenna is proposed to demonstrate the possibility of wideband operation at IR frequencies. The antenna geometry design is guided by the material properties of metals at IR frequencies. According to our numerical results, this nanoantenna has both high radiation efficiency and good impedance-matching properties over a wide frequency band (more than 122%) in the IR frequency band. The design is based on the well-known Vivaldi antenna placed on quartz substrate but operating as a pair instead of a single element. Such a pair of Vivaldi antennas oriented in opposite directions produces the main lobe in the broadside direction (normal to the axes of the antennas) rather than the usual peak gain along the axis (end fire) of a single Vivaldi antenna. The dual-Vivaldi nanoantenna is easy to fabricate in a conventional electron-beam lithography process, and it provides a large number of degrees of freedom, facilitating design for ultra-wideband operation. © 2011 Optical Society of America