Polarization-based optimal detection scheme for digital self-interference cancellation in full-duplex system

In order to detect and cancel the self-interference (SI) signal from desired binary phase-shift keying (BPSK) signal, the polarization-based optimal detection (POD) scheme for cancellation of digital SI in a full-duplex (FD) system is proposed. The POD scheme exploits the polarization domain to isolate the desired signal from the SI signal and then cancel the SI to obtain the interference-free desired signal at the receiver. In FD communication, after antenna and analog cancellation, the receiver still contains residual SI due to non-linearities of hardware imperfections. In POD scheme, a likelihood ratio expression is obtained, which isolates and detects SI bits from the desired bits. After isolation of these signal points, the POD scheme cancels the residual SI. As compared to the conventional schemes, the proposed POD scheme gives significantly low bit error rate (BER), a clear constellation diagram to obtain the boundary between desired and SI signal points, and increases the receiver's SI cancellation performance in low signal to interference ratio (SIR) environment.     

Design and Analysis of Polarization Diversity Antenna for Mobile Terminals

This letter presents an antenna design method for an orthogonally‐polarized dual antenna for use in mobile stations (MSs) and includes a verification method for improving the link‐level throughput performance of an MS that uses a proposed multiple‐input multiple‐output antenna. The link‐level throughput performance of an MS is strongly related to the correlation between antenna branches, which is determined by the cross polarization discrimination of the second branch antenna, both numerically and experimentally.     

On the electrically thick monopole: Part I--Theoretical solution

A new integral equation is formulated for the current distribution of an electrically thick, cylindrical antenna which is driven by a voltage across a finite gap on an infinitely large ground plane. Compared to the conventional integral equation of Hallen, this equation has an additional source term which can be expressed in terms of both the radius of the antenna and the width of the gap. A numerical solution of the integral equation has also been obtained by a so-called "approximate product-integration technique" and the results have been compared with the experimental data of a monopole antenna driven by a coaxial transmission line over an infinitely large ground plane. When the circumference of the antenna is comparable to a free-space wavelength, the experiment verifies that the theoretical model with finite gap excitation describes the experimental situation more properly than either the conventional model of a delta-function excitation on both outside and inside surfaces of the antenna, or the King-Wu model of a delta-fanction excitation only on the outside surface.     

Circularly polarised aperture antenna fed by CPW and built in MCM-Dtechnology

A new design for a circularly polarised aperture type antenna fed by a coplanar waveguide, is introduced. The antenna has been built in MCM-D technology which offers an easy way to reduce the leakage to the slotline mode of the CPW. The proposed antenna has been studied both theoretically and experimentally. The results show that the antenna has both a high impedance and high circular polarisation bandwidths. It is designed to operate around 25.5 GHz. Return loss, axial ratio, and radiation patterns are presented and briefly discussed     

Microwave delay characteristics of Cassegrainian antennas

An approach is presented in which the time an RF signal is delayed in propagating through a Cassegrainian antenna can be determined. The approach is based on the recognition that both the group delay (time) and the envelope delay (time) can be obtained from the antenna transfer function. Two antenna transfer functions are derived. The delay time under various antenna operating conditions is discussed.     

A High Gain and Broadband C-Band Aperture-Coupled Patch Antenna

A aperture-coupled patch antenna is designed with parasitic elements connecting to the rectangle ring on the bottom of antenna substrate through metal vias, which lead the current induced by patch radiator to the top surface of antenna substrate. Therefore, the effective radiation is enhanced and higher gain is achieved. The bandwidth is broadened simultaneously due to the structure of aperture-coupled patch antenna with parasitic elements. Compared to the conventional aperture-coupled patch antenna, the antenna gain increases averagely 2 dB due to the novel structure. Compared to patch antenna of electromagnetic band-gap, the dimensions of novel patch antenna greatly decreases, which can be used as element in the array antenna. Two kinds manufactured antenna are both measured in an anechoic chamber. The good agreements between numerical simulation and experimental prototype have been obtained.     

A Novel Compact Printed Antenna Used in TPMS or Other Complex and Variable Environments

A novel compact printed antenna used in tire pressure monitoring system (TPMS) is proposed and analyzed in this paper. The proposed antenna is printed on both sides of the dielectric substrate and the upper side consists of four parts: (1) the meandered radiating sections; (2) the additional strip line, which is used as a shorting connector and an additional radiating portion; (3) the feed microstrip line; and (4) the loading meandered sections, which are mainly used to improve the impedance bandwidth. The lower side consists of a meandered ground plane, which can also act as a balun choke and the extended parallel strap, which acts not only as a shorting connector but also as an impedance-tuning strap. A prototype of the proposed antenna with 0.17 lambda₀ in length, 0.017 lambda₀ in width and 0.0021 lambda₀ in height has been fabricated and tested. The relative impedance bandwidth of the proposed antenna reaches 22% (VSWR < 3.0) and 12% (VSWR < 2.0), and the antenna has an acceptable relative gain and its performance is relatively stable. Therefore, it also can be used in other complex and variable environments besides TPMS. When the length of the antenna is reduced to 0.098 lambda₀, the relative impedance bandwidth exceeds 28% (VSWR < 2.0). But the antenna's performance will become less stable, which may be the same as that of the conventional compact monopole antenna. Design details of the proposed antenna and the results of both simulations and experiments are presented and discussed.     

矩形腔十字裂缝天线

随着卫星移动通信技术的发展,一种能适合机载和地面移动载体卫星通信的天线越来越受到人们的青睐。该种天线应具有宽频带、圆极化和电扫描跟踪等特性,而矩形腔十字裂缝天线就是该种天线理想的辐射单元之一。基于矩量法分析,本文提出了计算矩形腔十字裂缝天线的数值方法,给出了天线单元的输入阻抗、增益和轴比等辐射特性的数值结果,进行了实验验证。验证表明,理论和实验结果有着很好的一致性。     

A 24-GHz Patch Array with a Power Amplifier/Low-Noise Amplifier MMIC

This paper presents an active patch array designed at 24 GHz. It can be used as a front-end component for a phased array. A series resonant array structure is chosen which is compact and easy excite. With 5 elements, the array proved a 12-dB antenna gain. A power amplifier and a low noise amplifier are designed on a single GaAs chip (PALNA). Bias switch is used in the PALNA, which greatly reduces the switch loss in a transceiver and increases the efficiency. 20-dB small signal gain is achieved in both power amplifier and low noise amplifier. The active patch array is built by the combination of the patch array and PALNA. The measured active gain of this antenna is 35-dB for the PA mode and 31-dB for the LNA mode. This active patch array can obtain an EIRP of 34 dBm with a total radiated power of 22dBm and a maximum PAE of 32%. To check the noise performance, we applied sources at both normal temperature and 77K (liquid nitrogen) and extracted the noise figure (3.5 dB) of the active antenna by the Y factor method. The results proved that the active antenna is working efficiently as both a transmitting and receiving antenna.     

Signal correlations and diversity gain of two-beam microcellantenna

The motivation of the present study is to investigate the possibility of using two independently directed antenna beams in a mobile base station to provide diversity gain and reduce fading problems in a microcellular environment. The signal correlation of the individual antenna beams is studied, and it is shown that correlation depends on beamwidth, separation angle of the antenna beams, and the location of the base-station antenna array. Signal correlations have been computed using narrow- and wide-beam antennas in two separate base-station antenna locations. Diversity gains of both antenna types have been optimized by selecting the beam orientations which minimize the signal correlation. The numerical simulations show that a considerable diversity gain can be obtained using this approach     

A wideband high gain dielectric resonator antenna for RF energy harvesting application

A novel high gain and broadband hybrid dielectric resonator antenna (DRA) is designed and experimentally validated. To obtain the wide impedance bandwidth, the proposed antenna geometry combines the dielectric resonator antenna and an underlying slot with a narrow rectangular notch, which effectively broadens the impedance bandwidth by merging the resonances of the slot and DRA. An inverted T-shaped feed line is used to excite both antennas, simultaneously. It supports amalgamation of different resonant modes of the both, DRA and slot antenna. The measured results show that the proposed antenna offers an impedance bandwidth of 120% from 1.67 to 6.7 GHz. The antenna gain is next enhanced by a reflector placed below the antenna at an optimum distance. On engineering the height and dimension of this reflector the antenna gain is improved from 2.2 dBi to 8.7 dBi at 1.7 GHz. Finally, antenna operation is attested experimentally with a rectifier circuit in the frequency range of 1.8–3.6 GHz, where various strong radio signals are freely available for RF energy harvesting. The measured maximum efficiency of the rectifier and rectenna circuit were found to be 74.4% and 61.4%, respectively.     

Theory of the terminated insulated antenna in a conducting medium

The general problem of the insulated antenna in an isotropic homogeneous medium of infinite extent is reviewed under the assumption that the medium is sufficiently conducting to permit the application of coaxial line theory. The currents and associated electromagnetic fields for the completely insulated antenna are obtained and the directional properties of the latter explained by comparison with a collinear array. An antenna in which only a central portion is insulated, while the ends are bare, is analyzed in terms of the theories of the insulated and bare antenna, both when the structure is driven by generators at the junctions of the bare and insulated sections and when it is driven by an internal coaxial feeder in the manner of a sleeve dipole. Finally, the center-driven insulated antenna with bare ends is investigated and its field is compared with that of the antenna driven at the junctions of the bare and insulated sections.     

矩形腔十字裂缝天线的研究

随着卫星移动通信技术的发展,一种能适合机载和地面移动载体卫星通信的天线越来越受到人们的青睐。该种天线要求具有宽频带、圆极化和电扫描跟踪等特性。矩形腔十字裂缝天线就是这种天线理想的辐射单元之一。基于矩量法的分析途径,本文提出了计算矩形腔十字裂缝天线的数值方法,给出天线单元的输入阻抗、增益和轴比等辐射特性的数值结果,并进行了实验实证。理论和实验结果有着很好的一致性。     

基于零折射超材料的双频高增益微带天线*

基于双面对称单环开口谐振器对结构奇异的电磁特性,设计了一种频率可控的各向异性零折射超材料。将这种零折射超材料应用于普通双频微带天线,制备了中心频率为5. 15GHz 和6. 8GHz 的零折射双频微带天线。仿真和测试结果显示,由于零折射超材料的引入,天线的侧向辐射减弱,方向性增强。在低频工作时,零折射微带天线E 面和H 面半功率波束宽度分别减小了29°和10°,增益提高了2. 2 dB。在高频工作时,零折射微带天线E面和H 面半功率波束宽度均减小了16毅,增益提高了2. 4 dB。将零折射超材料应用于微带天线的介质基板,为高性能双频微带天线设计提供了有效途径。     

A 94-GHz aperture-coupled micromachined microstrip antenna

This paper presents an aperture-coupled micromachined microstrip antenna operating at 94 GHz. The design consists of two stacked silicon substrates: (1) the top substrate, which carries the microstrip antenna, is micromachined to improve the radiation performance of the antenna and (2) the bottom substrate, which carries the microstrip feed line and the coupling slot. The measured return loss is -18 dB at 94 GHz for a 10-dB bandwidth of 10%. A maximum efficiency of 58±5% has been measured and the radiation patterns show a measured front-to-back ratio of -10 dB at 94 GHz. The measured mutual coupling is below -20 dB in both E- and H-plane directions due to the integration of small 50-μm silicon beams between the antennas. The micromachined microstrip antenna is an efficient solution to the vertical integration of antenna arrays at millimeter-wave frequencies     

一种槽耦合的双频双极化微带天线

设计了一种适用于基站天线的双频双极化微带天线单元,该天线单元采用槽耦合、多层贴片和对称馈电的结构形式。用商业软件Ansoft对天线的电特性进行仿真计算,制作了实验模型,测试结果优于仿真结果。天线在880-960MHz的GSM（全球移动通信系统）频段和1710～1880MHz的DCS（数字蜂窝系统）频段上的反射损耗均大于10dB,在两个频段上极化互相垂直的两个端口的隔离度均大于24dB。     

均匀照射赋形反射面天线设计

为提高反射面天线的照射均匀性，利用波束赋形技术设计一款工作在15 GHz的高性能偏置反射面天线.该天线由一个非均匀有理B样条（non-uniform rational B-splines，NURBS）反射面和一个介质棒馈源组成，NURBS反射面通过物理光学法结合Nelder-Mead优化算法来赋形，从而获得理想的天线辐射场.仿真结果表明，赋形后的反射面天线相对旁瓣电平低于-20 dB，增益在-2.7°~2.7°的波束范围内超过20 dBi，且浮动不超过1 dB.该天线具有结构简单、旁瓣低、增益均匀的特点，在卫星通信等领域具有重要作用.     

A biconical multibeam antenna for space-division multiple access

The biconical antenna is well known as an easy to build broad-band antenna with omnidirectional radiation. In this paper, the biconical antenna is modified for selective radiation in the azimuth direction. By enlarging the diameter of the coaxial feed to the biconical antenna, a set of higher order modes can be excited. In addition to the angle independent TEM mode, higher order TE-modes are also allowed for propagation, which result in an angle-dependent far-field pattern. Several features of this multimode excitation are of interest. Applying multiple input feed connectors allows simple rotation of the antenna beam by switching or, when independently operated, transmission and reception for communication in different angular directions for real-time space division multiple access (SDMA). As with conventional antenna arrays, adaptive pattern synthesis can also be realized by using multiple input feed connectors in combination with an appropriate amplitude and phase shifting network. The antenna allows an extremely flexible design of its characteristics at low cost, both requisites for SDMA communication     

Numerical analysis of arbitrarily shaped probe-excited single-armprinted wire antennas

A general integral equation technique is described for analysis of an arbitrarily shaped single-arm printed wire antenna excited through a vertical probe. A unified current integral equation is formulated on the basis of dyadic Green's functions and the reciprocity theorem. The current distribution is obtained by using a parametric moment method in which parameter segments are adopted for the printed wire instead of the commonly employed wire length segments. The radiation field solution involving both the printed antenna and vertical probe is also presented. The validity of the formulation is verified by comparing the numerically obtained input impedance and radiation patterns for a linear antenna and a meander antenna with measured data. A circular open loop and an Archimedian spiral are investigated to illustrate the applicability of the present technique