平面接收阵列天线的反射测量

在微波无线能量传输(MWPT)中,接收阵列天线通常采用分布式整流将接收到的微波能量转换为直流能量,其天线单元的最大入射功率决定了整流电路的设计.然而,接收阵列天线边缘单元所能接收到的功率小,使所接整流电路阻抗发生变化,与阵列天线单元失配造成较大的反射.首先从理论上论证了随着接收天线单元输入功率的变化,接收阵列天线边缘单元的反射大于中间单元.然后设计了一个低剖面(0.05λ2)、高定向性(12.5 dBi)、高前后比(27 dB)的微带准八木天线作为探头.最后测量了10×10平面接收阵列天线连接整流电路时的反射和入射功率分布图,并计算得到反射因子(反射因子定义为到达接收阵列天线单元表面上的反射功率和入射功率的比值)分布图.实验结果与理论分析一致,该实验为提高MWPT中接收端的效率起到指导作用.     

Synthesis of concentric ring antenna array for a wide isoflux pattern

This research presents the synthesis of the concentric ring antenna arrays for a wide coverage pattern. The synthesis process is formulated as an optimization of the antenna excitations. Harmony search algorithm and particle swarm optimization are implemented for this optimization problem. The antenna array considers disk patches at the L‐band. First, the synthesis regards the behavior of the antenna array modeled by the cavity model. Second, the mutual coupling is included by using the full wave simulation. This synthesis could be very useful in satellites with terrestrial global coverage. The obtained antenna array provides a wide uniform power density and reduces considerably the hardware complexity for a satellite antenna system. Copyright © 2014 John Wiley & Sons, Ltd.     

一种更低剖面的平面超宽带模块化天线阵列设计

针对现代社会多功能一体化、小型化、轻量化的趋势,并基于前人的研究,提出了一种更低剖面的平面超宽带模块化天线阵列.该阵列通过更换介质基板材料,并在天线末端添加金属片的方式,降低天线剖面的同时,保证天线在5.5～21.35 GHz频带内具备较好的性能.仿真结果表明,在边射、45°和55°三种扫描状态下,有源驻波比分别低于2.0、3.0和3.5;端口隔离度大部分低于-15 dB;交叉极化亦能低于-15 dB.在具备较好的天线性能同时,更低的剖面,有利于降低实际工程应用中的成本.     

24 GHz平面宽波束阵列天线设计

为满足车载毫米波雷达系统在盲区探测、防撞预警等应用场景时宽视场角的需求,设计了一款平面宽波束微带阵列天线。采用平面微带天线作为基本辐射单元组成3元阵列,提高天线增益。阵列天线采用背馈式同轴馈电,通过特定的馈电网络,使天线三个阵元的馈电功率之比为05∶1∶05,提高天线增益的同时抑制副瓣电平。并在平面天线的基础上添加寄生单元和开槽结构,进一步拓宽了天线的波束宽度,改善了天线的阻抗匹配性能。天线使用三维电磁仿真软件HFSS仿真验证,仿真结果表明该天线可工作于224～258 GHz,E面和H面3 dB波束宽度分别为49°和81°,天线最大增益为94 dB,第1副瓣电平小于-20 dB。天线整体尺寸为175 mm×119 mm×1308 mm,便于平面化应用和设备的小型化,有一定参考应用价值。     

一种更低剖面的平面超宽带模块化天线阵列设计

针对现代社会多功能一体化、小型化、轻量化的趋势,并基于前人的研究,提出了一种更低剖面的平面超宽带模块化天线阵列.该阵列通过更换介质基板材料,并在天线末端添加金属片的方式,降低天线剖面的同时,保证天线在5.5～21.35 GHz频带内具备较好的性能.仿真结果表明,在边射、45°和55°三种扫描状态下,有源驻波比分别低于2.0、3.0和3.5;端口隔离度大部分低于-15 dB;交叉极化亦能低于-15 dB.在具备较好的天线性能同时,更低的剖面,有利于降低实际工程应用中的成本.     

基于开口谐振环的三层高效电小天线设计

为提高电小天线的辐射效率,提出一款基于开口谐振环结构的3层小型化环形天线。天线的3层结构分为中间的馈电层和两侧的耦合层,采用电磁耦合方法实现激励。在馈电层设计了一种倒“山”形匹配网络,弥补了传统耦合馈电SRR天线存在部分反向电流的缺陷;通过加载耦合环结构实现强磁耦合,降低天线的金属损耗;在耦合层与馈电层间设计支柱固定的空气间隙,有效地降低介质损耗,从而提高辐射效率。采用电磁仿真软件对天线进行设计,并分析了介质基板对天线性能的影响。对设计的天线进行了实物研制与测试。结果表明,实测结果与仿真结果基本吻合,天线的中心频率为50.03 MHz,电尺寸为0.045λ₀×0.045λ₀×0.01λ₀(λ₀为工作波长),其在水平面内具有良好的全向性,辐射效率大于41%。     

Design of a log-periodic aperture-fed microstrip antenna array

The narrow bandwidth of a microstrip antenna is one of the important features that restricts its wide usage, although it possesses many advantages such as low profile, light weight, etc. Various techniques have been used to enhance the bandwidth of this kind of antenna. This paper presents a planar microstrip array designed by the log-periodic technique for wideband operation in the frequency range of 1.7-5.5 GHz. The elements of the array are orthogonal patches, aperture coupled fed by a microstrip line. The far-field pattern of the array, for a number of frequencies in the above range, has been computed by a simulation procedure.     

Design and study of a compact planar ultra-wideband antenna

In this paper, a novel, small, and compact planar antenna for ultra-wideband (UWB) applications is proposed. The antenna is an extension of microstrip slot antenna technology. To achieve ultra-wideband characteristics, a tapered microstrip fork-shaped stub has been employed. A symmetric polygon wide slot has been placed on the antenna ground. The design was investigated numerically to obtain proper dimensions for the antenna and a prototype was constructed. The return loss, pattern and gain of the prototype antenna have been measured. The transient pulse signal fidelity has also been investigated by finite-difference time-domain (FDTD) method. Experimental results show that the proposed antenna design has promising characteristics for UWB applications. __________ Translated from Chinese Journal of Radio Science, 2006, 21(4): 582–585 [译自: 电波科学学报]     

An antenna array synthesis technique by the help of Chebyshev polynomials

Contents A method for synthesis of antenna arrays with a given number of sidelobes and sidelobe levels is discussed. The pattern is given as a multiplication of a Chebyshev polynomial of n^th degree with the one of first degree. The radiation pattern of a wire antenna in a form similar to that of an array with point sources is also given by the method of moments. So the synthesis procedure can be reduced. Several examples show the applicability of the method.

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Eine Methode für den Entwurf von Hilfe der Chebyschevschen Polynome

Übersicht In der vorliegenden Arbeit wird eine Methode für den Entwurf von strahlungsgekoppelten Drahtstrukturen mit vorgegebener Anzahl der Nebenzipfel und Nebenkeulendämpfung behandelt. Das Richtdiagramm wird als Produkt eines Chebyshevschen Polynomsn-ten Grades mit einem Polynom ersten Grades angesehen. Außerdem wird mit Hilfe der Momentenmethode die Strahlungscharakteristik einer Drahtantenne in Form einer aus Punktquellen bestehenden strahlenden Linie angegeben. Dadurch wird der Entwurf auf letztere zurückgeführt. Mehrere Beispiele deuten die Anwendbarkeit dieser Methode an.

     

Analysis of a linear antenna array including the effects of mutualcoupling

A tutorial on the analysis of linear antenna array performance is presented. Use is made of a rapidly converging algorithm for the calculation of element currents that include the effects of mutual impedance. The procedure makes it possible to introduce realistic antenna problems into an advanced undergraduate or first graduate antennas course. The procedure is straightforward, and lends itself to teaching the topic by an axiomatic approach. The numerical examples illustrate in principle which of the parameters of the array are affected by the mutual coupling, and to what extent     

天线平面近场测量的扫描面位置误差分析

本文基于天线平面近场测量技术的基本理论,利用数值分析方法深入分析了天线平面近场测量中有限扫描面位置误差,及其对天线远场特性和测量精度的影响.通过与理论结果的比较,给出了扫描面位置误差源所产生误差和误差的数量级,即天线方向性图的不确定度.该研究为天线近场测量技术的误差补偿提供了一定的理论依据.     

Position only pattern nulling of linear antenna array by using a clonal selection algorithm (CLONALG)

In this paper, a clonal selection algorithm (CLONALG) based on clonal selection principle of immune system has been used for null steering in the antenna radiation pattern by controlling only the element positions of a linear array. Numerical examples of Chebyshev pattern with the single, multiple and broad nulls imposed at the directions of interference are given to show the accuracy and flexibility of the CLONALG. The sensitivity of the achieved patterns due to small variations of the element positions is also investigated by truncating the element positions.     

Synthesis of thinned concentric ring array antenna in predefined phi‐planes using binary firefly and binary particle swarm optimization algorithm

A binary firefly algorithm inspired by the behavior of artificial fireflies has been applied to thin a planar concentric ring array antenna to minimize the peak sidelobe level in a number of predefined ϕ‐planes. Two different cases comprising two different design specifications for the optimized thinned array have been considered. In the first case, the array is thinned to reduce the peak sidelobe level while keeping the first null beamwidth and half power beamwidth of the array below their specified values in all the defined ϕ‐planes. In the second case, peak sidelobe level of the array is reduced regardless of any pre‐specified values of first null beamwidth and half power beamwidth. To illustrate the superiority of binary firefly algorithm, the thinning of the array for the two different cases has been compared with binary particle swarm optimization algorithm. Results clearly show the superiority of binary firefly algorithm in finding optimum solutions for both cases. Copyright © 2014 John Wiley & Sons, Ltd.     

On‐chip neural cell cultivation using agarose‐microchamber array constructed by a photothermal etching method

We have developed a novel method for on‐chip cultivation of neural cells in a flexible agarose‐microchamber array on a glass slide. The agarose microchamber is a micrometer‐order cavity constructed on the surface of an agarose layer by molding a 50‐µm‐high square/circular micro‐cast of thick SU‐8 photoresist. In addition, the shape of the agarose microchamber was rearranged by using the photothermal etching method, in which we used an infrared (1064‐nm) focused laser beam as the heat source to melt and remove a portion of agarose gel at the heating spot. With the photothermal etching method, we can also manufacture narrow tunnel‐shaped channels between microchambers. When nerve cells were cultured on the agar‐microchamber array chip, the nerve cells in two adjacent microchambers connected through the photothermal‐etched channel after 48 hours of cultivation. Those results suggest the potential of an agarose‐microchamber array integrated with the photothermal etching method for the next stage of single cell cultivation and measurement of nerve cells, such as real‐time control of cell interactions during cultivation. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(2): 37–42, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10215     

Analysis of a dual‐resonant multiple split‐ring patch antenna

The design and analysis of a new 0.06λ × 0.09λ compact circular polarized square‐shaped dual‐resonant multiple split‐ring patch antenna on a 1.905‐mm‐thick high‐dielectric ceramic–polytetrafluoroethylene composite is presented. The proposed antenna was designed and analyzed by using a high‐frequency electromagnetic simulator based on the finite element method and was fabricated on a printed circuit board. The measured ?10 dB return loss bandwidths were 44.44% (0.7–1.1 GHz) and 34% (2.25–3.1 GHz) at 0.9 and 2.5 GHz center frequencies, respectively. The measured radiation patterns with 5.9 and 4.0 dBi maximum gains were symmetric and steady, making the proposed antenna suitable for radio frequency identification, wireless local area network, wireless body area network, Low Rate‐Wireless Personal Area Network (LR‐WPAN), and so on. The effects of linewidth, dielectric property of the substrate materials, and number of split rings on the return loss were investigated. The surface current distribution over the radiating patch and the characteristics of the Resistance, Inductance, Capacitance (RLC) equivalent circuit of the proposed antenna were also analyzed. Copyright © 2013 John Wiley & Sons, Ltd.     

用于天线阵馈电的高隔离度一分八不等比功分器设计

随着阵列天线研制技术的发展,对馈电网络的特性提出了更高的要求,然而关于Ku波段高隔离度不等比天线阵馈电网络的文献却不是很多.利用两级λ/4阻抗变换器级联实现功分器频带展宽,利用两级隔离电阻提高端口隔离度,通过在3λ/4阻抗变换线上开槽实现结构紧凑的一分二不等比功分器.在此基础上,由三级两路功率分配器级联构成Ku波段高隔离度一分八不等比功分器.该功分器已成功应用于天线阵馈电网络的设计.     

Radiation pattern shaping of a mobile base station antenna array using a particle swarm optimization based technique

A new technique of shaping the radiation pattern of an antenna array is presented. The technique aims at finding the appropriate geometry of the antenna array as well as the excitation of the array elements in order to produce a radiation pattern of the desired shape. A suitable optimization procedure is applied using a particle swarm optimization algorithm. The technique has been successfully applied to collinear arrays and seems to be suitable for beam- forming of antenna arrays used by mobile communications base stations.     

六频段手机天线的设计

提出了一种应用在手机终端上,同时能够覆盖无线通信频段中六频段的新型天线设计。在设计中应用到了多个短截线和条带线来产生多频段。整个天线包括接地面在内的体积是38mm×140mm×7mm。该天线能够工作在LTE700、AMPS800、GSM900、ISM/Bluetooth、WLAN和WiMAX这6个频段。根据计算、仿真优化的尺寸,对天线原型进行了制作与测试,在最后给出了软件仿真结果和实际测试结果,结果显示两者基本吻合。     

Numerical analysis of ground plane size effects on patch array antenna characteristics for mobile satellite communications

In this research, a patch array antenna for mobile satellite communications aiming at ETS‐VIII applications has been developed. The ground plane size effects on the antenna characteristics were investigated. Finite and infinite ground planes were analysed by the finite integration technique (FIT) for time domain analysis, the finite element method (FEM) and the method of moments (MoM) for spectral domain analysis. Then measurements of the fabricated antenna were performed to confirm the analysis results. It is clear that the frequency characteristics of the axial ratio are influenced by the variation in the ground plane size. When the ground plane size is increased, the edge‐diffracted field causes tilting of the beam in the direction of low elevation angles and causes a decrease in the maximum gain and in the 3 dB‐beamwidth of axial ratio in the elevation plane. In the conical‐cut direction, an increase in ground plane size induces a decrease in the 3 dB‐beamwidth of axial ratio for FEM, but shows the opposite result for FIT and measurement. In addition, an increase in ground plane size also induces increases in maximum gain and its 6 dBic‐beamwidth along with a shift in the maximum gain in the direction of low azimuth angle. Copyright © 2004 John Wiley & Sons, Ltd.     

Mathematical model of bessel beamformer with automatic gain control for smart antenna array system in Rayleigh fading channel

This paper analyzes the mathematical model of a Bessel beamformer with automatic gain control (AGC) in a multipath scenario using a digital modulation technique and makes comparison with the one without AGC. The Bessel beamformer with AGC is designated here as the modified Bessel beamformer. The desired useful and interfering signals operate with the same carrier frequency and Doppler shifts but in different directions. Based on simulation results, this modified Bessel beamformer is shown to provide an optimum solution and to accommodate more users in real‐time base stations of mobile communication system when implemented on smart antenna array systems. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.