Showing papers on "Conformal antenna published in 2013"

Reconfigurable Antennas

Abstract: Reconfigurable antennas change polarization, operating frequency, or far-field pattern in order to cope with changing system parameters. This paper reviews some of the past and current technology applicable to reconfigurable antennas, with several examples of implementations. Mechanically movable parts and arrays are discussed, as well as more-recent semiconductor-component and tunable-material technologies applicable to reconfigurable antennas.

Single-Layer Single-Patch Dual-Band and Triple-Band Patch Antennas

Abstract: Recently, it was shown that a dual- or triple-band patch antenna can be designed by cutting U-slots in the patch of a broadband antenna, and the method was applied to the L-probe fed patch, the M-probe fed patch, coax-fed stacked patches, and aperture coupled stacked patches. All these cases involve either a rather complicated feed, or more than one patch, or more than one layer. In this communication, this method is applied to a broadband U-slot patch antenna. When one additional U-slot patch is cut in the patch, a dual-band antenna results. When two additional U-slot patches are cut in the patch, a triple-band antenna results. The advantages of the resultant configurations are (1) the feed is simple and (2) the structures remain single-layer and single-patch. Both simulation and measurement results are presented to demonstrate the feasibility of this design.

Compact Circularly Polarized Antennas Combining Meta-Surfaces and Strong Space-Filling Meta-Resonators

Abstract: Reduced-size single-feed circularly-polarized (CP) patch antennas are proposed and investigated based on the strategy of combining meta-surfaces and meta-resonators owning strong space-filling capability. They all comprise a slot-loaded square patch printed over a well designed reactive impedance surface (artificial meta-surface with magnetic response at the resonant frequency) for improved antenna performances and size reduction. The complementary crossbar fractal tree (CCFT) slot and three-turn complementary spiral resonators (TCSRs) with asymmetric gap orientation are employed as meta-resonators to render the antennas to radiate CP waves in single-band or dual-band operation and to facilitate further miniaturization. Numerical and experimental results indicate that these antennas owning a maximum size of 0.262λ0 × 0.262λ0 around 3 GHz exhibit a comparable impedance and axial ratio (AR) bandwidth over 1.05% and high gain of more than 4.15 dBic, predicting promising applications in portable and handheld communication systems.

Antenna selection in measured massive MIMO channels using convex optimization

Abstract: Massive MIMO, also known as very-large MIMO or large-scale antenna systems, is a new technique that potentially can offer large network capacities in multi-user scenarios, where the base stations are equipped with a large number of antennas simultaneously serving multiple single-antenna users on the same frequency. However, the radio-frequency (RF) chains associated with the antennas increase the system complexity and hardware cost. Antenna selection is a signal processing technique that can help reduce the number of RF chains, while preserving the system performance at a certain required level. We study the transmit antenna selection in measured massive MIMO channels from several measurement campaigns in the 2.6 GHz frequency range. Convex optimization is used to select the antenna subset that maximizes the dirty-paper coding (DPC) capacity in the downlink. With a certain number of RF chains, we increase the number of base station antennas from the same as the RF chains to a large number, from which we perform the antenna selection. The investigation shows that with more available antennas than RF chains, the antenna selection can significantly improve the system performance, especially for a compact cylindrical array, which without this antenna selection shows lower performance than a physically large linear array with the same number of elements, in the studied scenarios.

Millimeter-Wave Shaped-Beam Substrate Integrated Conformal Array Antenna

Abstract: A millimeter-wave shaped-beam substrate integrated conformal array antenna is demonstrated in this paper After discussing the influence of conformal shape on the characteristics of a substrate integrated waveguide (SIW) and a radiating slot, an array mounted on a cylindrical surface with a radius of 20 mm, ie, 23 λ, is synthesized at the center frequency of 35 GHz All components, including a 1-to-8 divider, a phase compensated network and an 8 × 8 slot array are fabricated in a single dielectric substrate together In measurement, it has a - 274 dB sidelobe level (SLL) beam in H-plane and a flat-topped fan beam with -38° ~ 37° 3 dB beamwidth in E-plane at the center frequency of 35 GHz The cross polarization is lower than -417 dB at the beam direction Experimental results agree well with simulations, thus validating our design This SIW scheme is able to solve the difficulty of integration between conformal array elements and a feed network in millimeter-wave frequency band, while avoid radiation leakage and element-to-element parasitic cross-coupling from the feed network

A Self-Adapting Flexible (SELFLEX) Antenna Array for Changing Conformal Surface Applications

Abstract: A phased-array test platform for studying the self-adapting capabilities of conformal antennas is developed and presented. Specifically, a four-port 2.45-GHz receiver with voltage controlled phase shifters and attenuators is designed along with four individual printed microstrip patch antennas attached to a conformal surface. Each antenna is connected to the corresponding receiver port with a flexible SMA cable. It is shown that with appropriate phase compensation, the distorted radiation pattern of the array can be recovered as the surface of the conformal array changes shape. This pattern recovery information is then used to develop a new self-adapting flexible 1 t 4 microstrip antenna array with an embedded flexible sensor system. In particular, a flexible resistive sensor is used to measure the deformation of the substrate of a conformal antenna array, while a sensor circuit is used to measure the changing resistance. The circuit then uses this information to control the individual voltage of the phase shifters of each radiating element in the array. It is shown that with appropriate phase compensation, the radiation properties of the array can be autonomously recovered as the surface of the flexible array changes shape during normal operation. Throughout this work, measurements are shown to agree with analytical solutions and simulations.

Frequency Reconfigurable Microstrip Loop Antenna Covering LTE Bands With MIMO Implementation and Wideband Microstrip Slot Antenna all for Portable Wireless DTV Media Player

Abstract: A microstrip slot antenna covering Digital TV (DTV) and frequency reconfigurable microstrip printed loop antenna operating at LTE bands 3 (1.8 GHz) and 7 (2.6 GHz) with multiple-input-multiple-output (MIMO) implementation are designed which can find applications in portable wireless DTV media players. The DTV antenna is matched from 496-862 MHz and LTE bands 3 and 7 from 1710-1880 MHz and 2500-2700 MHz, respectively, all considering S11 = -6 dB matching criterion. Further, the LTE bands antennas are frequency reconfigurable antennas and its MIMO implementation shows an envelope correlation (EC) below 0.22 for both the LTE bands. Prototype antennas were fabricated and experimental verification was performed.

A Hybrid IWO/PSO Algorithm for Pattern Synthesis of Conformal Phased Arrays

Abstract: This communication introduces a hybrid invasive weed optimization and particle swarm optimization (IWO/PSO) algorithm dedicated to pattern synthesis of conformal arrays. A 3 $\, \times \,$ 9 cylindrical conformal microstrip array is studied to demonstrate the proposed algorithm. The active element pattern of each element in the conformal array is extracted and the phase and amplitude of each excited voltage are optimized to achieve the required goals using the hybrid IWO/PSO algorithm. The results indicate that, compared with standard IWO and PSO algorithms, the introduced hybrid algorithm maintains the respective advantages of the IWO and PSO algorithms while excluding their respective deficiencies. Moreover, the hybrid algorithm is very reliable in achieving global optimality.

Enhancing the Critical Current of a Superconducting Film in a Wide Range of Magnetic Fields with a Conformal Array of Nanoscale Holes.

Abstract: This is a copy of an article published in the Physical Review B © 2013 American Physical Society. DOI: 10.1103/PhysRevB.87.220501

New Wideband Printed Antennas for Medical Applications

Abstract: Biomedical industry is in continuous growth in the last few years. Low profile compact antennas are crucial in the development of wearable human biomedical systems. The polarization of the proposed antenna may be linear or dual polarized. Design considerations, computational results and measured results on the human body of several compact wideband microstrip antennas with high efficiency at 434 MHz ± 5% are presented in this paper. The compact dual polarized antenna dimensions are 5 × 5 × 0.05 cm. The antenna beam width is around 100°. The antennas gain is around 0 to 2 dBi. The proposed antenna may be used in Medicare RF systems. The antennas S11 results for different belt thickness, shirt thickness and air spacing between the antennas and human body are presented in this paper. If the air spacing between the new dual polarized antenna and the human body is increased from 0 mm to 5 mm the antenna resonant frequency is shifted by 5%.

Implantable antennas: The challenge of efficiency

Abstract: A discussion on the main challenges designing efficient antennas for bio-implantable communication devices is presented, along with some of the main issues encountered in their characterization. Such devices are used in conjunction with health monitoring or health care systems. Implantable antennas are, by nature, electrically small, and difficulties linked to electrically small antenna design apply. But implants are also located in a lossy host body, which induces a major change of paradigm with classic Electrically Small Antennas (ESA), as the main design challenge for implantable antennas will be to reach an acceptable efficiency, and not a broad enough bandwidth. In this paper, we present first the main challenges to be met in designing implantable antennas, followed by suggestions for an efficient design procedure. Finally, the specific difficulties in characterizing implantable antennas are emphasized.

3D beamforming designs for Single User MISO systems

Abstract: In this paper, we study a transmit beamforming technique for multiple input single output downlink single-user systems with three dimensional antennas where a transmit antenna gain is determined in three dimensional coordinates. In general, the transmit antenna gain is controlled by adjusting the boresight of antennas in directional antennas. To derive the optimal tilting angles for the directional antenna systems, we provide the probability density functions (PDF) of the three dimensional user distribution. Furthermore, based on the PDF, the analysis for the average rates of passive and active antenna systems is presented. Simulation results verify the accuracy of the performance analysis.

A Resonant Printed Monopole Antenna With an Embedded Non-Foster Matching Network

Abstract: Non-Foster reactive elements are embedded inside compact resonant antennas, rather than being employed in matching networks located at the antenna terminals. These embedded non-Foster elements interact with the inherent Foster reactances of the antenna, resulting in a broadband antenna with a high radiation resistance. The class of suitable antennas for this application is discussed, a design procedure is presented and a sensitivity and a stability analysis are performed. Finally, experimental results for a representative non-Foster antenna are presented and discussed.

Dual-Band Suspended-Plate Wearable Textile Antenna

Abstract: A novel, dual-band wearable textile antenna fabricated using conductive textiles for operation in both ISM and HiperLAN applications is presented. Its concept is based on the suspended-plate antenna. It features a 60 $\,\times\,$ 45 mm $^2$ rectangular radiating element suspended over a 80 $\,\times\,$ 60 mm $^{2}$ ground plane using a 5-mm foam substrate. The proposed rectangular radiator is modified using slots, slits, and shorting posts to enable dual-band resonance and broad bandwidths in both frequency bands: 277 MHz (2.22–2.48 GHz) in the ISM and 850 MHz (4.95–5.80 GHz) in the HiperLAN band. The antenna radiates unidirectionally, and the ground plane avoids coupling to the users' body. The SP-WTA shows a total efficiency between 67% and 89% and a peak gain of 8.33 dB.

Measurement-Based Analysis: The Effect of Complementary Antennas and Diversity on Vehicle-to-Vehicle Communication

Abstract: In vehicle-to-vehicle (V2V) communication systems, the antennas are prone to shadowing, and the antenna gain is dissimilar even for same antenna elements if mounted at different positions on the car. This letter investigates the impact of antenna placement based on channel measurements performed with four omnidirectional antennas mounted on the roof, bumper, windscreen, and left-side mirror of the transmitter and receiver cars. Results suggest to use antennas with complementary characteristics, e.g., antennas on each side, mounted on the roof and bumper, to exploit diversity and decrease the effect of shadowing.

Broadband Patch Antennas Fed by Novel Tuned Loop

Abstract: A novel tuned loop feed for patch antennas is described The arrangement provides a symmetrical excitation of the patch with a double tuned response with enhanced bandwidth The tuned loop together with the patch can be seen as a band pass filter comprising a series resonator and parallel resonator tuned to the same frequency The tuned loop can easily be implemented as a microstrip PCB A dual polarized patch antenna can be designed for diversity reception using this technique Measured results are given, showing that this feed is effective in broadening the bandwidth of patch antennas This configuration is a good candidate for radiating elements in cellular base station antennas

Optimization and fabrication by 3D printing of a volcano smoke antenna for UWB applications

Abstract: Ultra-Wideband (UWB) technology is a low power and high data rate technology for applications like radar imaging, sensor data collection, position localization and medical imaging. In UWB systems, antennas plays a critical role as they are required to be compact and wideband with minimal pulse distortion. This paper present a small three-dimensional volcano smoke antenna, designed and optimized in a FDTD full-wave simulator and then fabricated by 3D printing. The antenna has a simulated 10 dB impedance bandwidth from 3.2 GHz to 12.6 GHz, suitable for the UWB band. The measured return-loss for the 3D printed antenna shows a good agreement with the simulations. Hence, 3D printing can be used as an alternative method for fabricating complex shaped three-dimensional antennas.

Broadband UHF RFID Passive Tag Antenna for Near-Body Applications

Abstract: One challenge for UHF RFID passive tag design is to obtain a low-profile antenna that minimizes the influence of near-body or attached objects without sacrificing both read range and universal UHF RFID band interoperability. A new improved design of a RFID passive tag antenna is presented that performs well near problematic surfaces (human body, liquids, metals) across most of the universal UHF RFID (840-960 MHz) band. The antenna is based on a low-profile printed configuration with slots, and it is evaluated through extensive simulations and experimental tests.

Array Antenna Limitations

Abstract: This letter defines a physical-bound-based array figure of merit for both single and multiband array antennas. It provides a measure to compare their performance with respect to return loss, bandwidth(s), thickness of the array over the ground plane, and scan range. The result is based on a sum-rule result of Rozanov-type for linear polarization. For single-band antennas, it extends an existing limit for a given fixed scan-angle to include the whole scan range of the array, as well as the unit-cell structure in the bound. The letter ends with an investigation of the array figure of merit for some wideband and/or wide-scan antennas with linear polarization. We find arrays with a figure of merit >0.6 that empirically defines high-performance antennas with respect to this measure.

MIMO performance evaluation of automotive qualified LTE antennas

Abstract: Future vehicles are expected to integrate multiple radio access technologies in order to support more efficiently traffic and infotainment applications. The focus of this paper is the performance evaluation of 3GPP Long Term Evolution (LTE) for automotive applications. The results presented are based on field measurements, which were carried out on a test track in Munich, Germany. The focus is the spectrum in 800 MHz, which is more challenging for multiple-input multiple-output (MIMO) antenna designs due to the difficulties of antenna decoupling. For the investigation an automotive qualified LTE MIMO antenna system is used. The presented results demonstrate that a performance deterioration of the antenna system occurs in areas close to the base station. It is shown that the deterioration is caused by shadowing between the two printed circuit board antennas comprising the antenna system. Moreover, it is illustrated that the signal-to-noise-plus-interference ratio (SINR), as opposed to the received signal strength indicator (RSSI), is a better suited parameter to determine the performance of the LTE link.

Fast Co-Polar and Cross-Polar 3D Pattern Synthesis With Dynamic Range Ratio Reduction for Conformal Antenna Arrays

Abstract: This paper presents a fast method for conformal antenna arrays that enables the synthesis of 3D co-polar and cross-polar patterns, simultaneously reducing the dynamic range ratio (DRR) of the array excitations. The power synthesis problem is reduced to a field synthesis one by introducing two auxiliary phase patterns: one for the co-polar pattern and the other for the cross-polar pattern. The problem is then iteratively solved with respect to the two auxiliary phase patterns and to the array excitations. A modified version of the method is also proposed, for the particular case where the DRR reduction is not required, obtaining a further strong reduction of the computational time.

Microstrip antenna design using neural networks optimized by PSO

Abstract: Microstrip antennas became very attractive due to their features like small dimensions, simplicity, conformability and low cost of production. The production these antennas for wireless communication is focused to design efficient, wide band, antennas that easily can be incorporated into various systems. Design parameters of microstrip antenna need to be calculated in very high accuracy to ensure proper functioning. Design of the rectangular or circular microstrip patch antenna requires high accuracy of calculations, and it is not so easy task. The known models (transmission line model or cavity model) give less accurate results. Simulations based on full-wave analysis techniques, such as CST Studio SuiteTM, enable more accurate analysis of microstrip antenna characteristics, but they suffer from time consuming, intensive computations. Demand for fast and enough accurate computations can be satisfied using neural network models. This work studies microstrip patch antenna design using artificial neural network optimized by PSO (Particle Swarm Optimization) algorithm. According to neural network design results an antenna was made. The calculated and neural network results are compared with measured antenna values.

Design of a Rectangular Microstrip Patch Antenna Using Inset Feed Technique

Abstract: Today in the world of communication systems the most widely researched area is of wireless technology and a study of communication systems is incomplete without an understanding of the operation of the antennas. In the recent years of development in communication systems a need for the development of lightweight, compact and cost-effective antennas that are capable of maintaining high performance over a wide spectrum of frequencies. This technological trend has focused much effort into the design of a Micro strip patch antenna. In this work, the simulation tool of IE3D is used to study the performance and gain of the rectangular Microstrip patch antenna. The design and simulation of patch antennas is widely used in mobile cellular phones today, and our emphasis in this work is on optimization of a 2.4 GHz rectangular Microstrip patch antenna. The return loss and the various gain plots have been studied along with the radiation patterns.

High‐isolation 2.4/5.2/5.8 GHz WLAN MIMO antenna array for laptop computer application

Abstract: An isolation technique for two small-size triband wireless wide area network (WLAN) multiple-input multiple-output (MIMO) laptop computer antennas covering the 2.4/5.2/5.8 GHz bands is presented. The proposed WLAN MIMO antennas have measured isolation of better than −21 dB in the 2.4 GHz band and −32 dB in the 5.2/5.8 GHz bands in this study. In addition to enhanced isolation achieved, good antenna efficiencies of better than about 70 and 90%, respectively, in the 2.4 GHz and 5.2/5.8 GHz bands are obtained for the two antennas. The WLAN MIMO antenna array having a planar structure of size 9 × 55 mm2 is to be mounted at the top edge of the supporting metal plate of the laptop display. The two antennas can be fabricated at low cost on a thin FR4 substrate and are of a simple structure comprising a driven strip and a shorted strip, which provides two wide operating bands to cover the 2.4 and 5.2/5.8 GHz bands. Between the two antennas, there is an isolation element formed by a protruded ground plane and a spiral open slot embedded therein. The isolation element leads to enhanced isolation between the antennas in the 2.4/5.2/5.8 GHz WLAN bands and good antenna efficiencies for the antennas as well. Details of the isolation technique for the WLAN MIMO antennas are described, and the obtained results are presented and discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:382–387, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27279

Space Mapping Optimization of Handset Antennas Exploiting Thin-Wire Models

Abstract: A handset antenna modeling and design technique using space mapping (SM) is presented. Thin-wire models are exploited as coarse models in the SM algorithms, while the fine models are high-accuracy electromagnetic simulations. The thin-wire models capture the basic physics of handset antennas but are not as accurate as the fine model. On the other hand, they are computationally cheap when analyzed by the method of moments solvers. Detailed guidelines for building thin-wire models are provided. Two SM algorithms are employed: 1) implicit, input and output space mapping and 2) implicit and output space mapping. An internal dual-band patch antenna and an arm-folded planar inverted F antenna are designed through our approach. For comparison, direct optimizations have been performed in each example.

Demonstration of an Octave-Bandwidth Negligible-Loss Metamaterial Horn Antenna for Satellite Applications

Abstract: This paper reports on the detailed design and experimental demonstration of a metamaterial-enabled low-sidelobe horn antenna (metahorn) based on principles similar to those of earlier soft horn antennas. The target application is a linearly polarized feed horn in the super-extended C-band (3.4-6.725 GHz) for communication satellite reflector antennas. The paper describes the detailed design and manufacturing of the -plane metamaterial liner (metaliner) based on a freestanding wire grid without the need for a dielectric substrate material. The measured copolarized and cross-polarized antenna patterns from the feed horn demonstrate over an octave pattern bandwidth with negligible loss. The results show similar bandwidth with lower sidelobes and backlobes than those of the trifurcated horn that is currently used as the standard C-band feed for single linear polarization. This demonstration shows promise for lightweight metamaterial horns to replace heavy and expensive C-band corrugated horns.

Optimizing Power Transfer Efficiency and Bandwidth for Near Field Communication Systems

Abstract: Near-field communication (NFC) is a specification for short-range wireless links operating at 13.56 MHz in the high-frequency (HF) band. The achievable bandwidth, efficiency, and range of lightweight, size-constrained, low-power NFC systems are limited by fundamental theorems of small antenna theory. We develop a relationship between near field power transfer and radiation efficiency for dipole-type antennas, which is applicable to both communications and wireless power transfer applications, and present modeled and experimentally measured results for the bandwidth efficiency product of two ferrite loop antenna designs. The model is used to determine the optimal geometrical parameters that maximize this figure of merit for a given antenna size. Modeled and measured results show that ferrite loops can approach theoretical limits on performance for the bandwidth efficiency product of an antenna with a given size.

A review on wideband microstrip patch antenna design techniques

Abstract: This review article presents an overview of the design techniques for broadband microstrip patch antennas Basically, a microstrip patch antenna is composed of a trace of copper or any other metal of any geometry on one side of a standard printed circuit board (PCB) substrate with other side grounded This antenna can be fed using coaxial, stripline, aperture-coupling or proximity-coupling methods The idea of patch antenna slowly attracted the antenna community in 20 years after its birth in early 50's The patch antennas are very useful because of their; low weight, ability to conform to any geometrical shape, easy integration with HMICs and MMICs, and low cost fabrication Their major drawback is their narrow bandwidth which makes them unsuitable for modern-day wireless communication technologies Through extensive studies in the last few decades on antenna performance improvement, various techniques have been developed to enhance the bandwidth The current research focus is on the reconfigurable antennas These can provide wide bandwidth performance; multi-band functionality; the frequencies and bandwidths can be reconfigured as well The microstrip antennas are widely used in military, industrial and commercial sectors This article opens with short introduction of basic characteristics, feeding methods and analysis techniques of patch antenna After that review of bandwidth enhancement techniques, multi-band and wideband reconfigurable antenna designs are presented The article closes with conclusions and future perspective

Impedance Properties and Radiation Efficiency of Electrically Small Double and Triple Split-Ring Antennas for UHF RFID Applications

Abstract: This letter is targeted at investigation of electrically small planar antennas, formed by double and triple split rings that are intended to serve as tag antennas operated within the European UHF RFID band. An extensive systematic study of possible geometrical configurations demonstrates the range of their achievable input impedances (complex conjugate to typical UHF RFID integrated circuits) in the case that both structures electrically decrease below the limit for electrically small antennas, i.e., $ka . The advantage of the triple split-ring version over the standard double split-ring one consists in reduction in its electrical size and concurrent maintenance of the required range of input impedances and high radiation efficiency. Samples of both structures were manufactured and measured, and their electrical properties were critically compared.

Design of ultra wide-band low-band implant antennas for capsule endoscope application

Abstract: This paper investigated two kinds of design of implant antennas in ultra wide-band (UWB) low-band (34-48 GHz) for capsule endoscopes First, two kinds of hemispherical antennas, one has a helical structure and the other has a loop structure, were designed The hemispherical antennas match for the shape of capsule endoscopes The reflection coefficient S11 and the directivity of the hemispherical antennas in UWB low-band were investigated in detail Next, a simplified planar design of the hemispherical loop antenna was proposed for being easy to fabricate The characteristic of the planar loop antenna in UWB low-band was investigated by both numerical simulation and experiment In addition to the S11, the path loss of the fabricated planar loop antenna was also measured in a fluid phantom simulating a human body tissue, with a planar unbalance dipole antenna as the receiving antenna The measured path loss was compared with the simulated result, and good agreement was confirmed between them