高端口隔离度双极化贴片天线设计

针对WLAN的MIMO系统应用要求,并缩小天线所占据的空间,设计具有高端口隔离度的双极化贴片天线。采用共面带状线馈电的环形贴片和微带馈电单极贴片相结合形式,利用环形辐射元与单极子辐射元产生正交线极化的特点,实现双馈双极化天线。实验结果显示,所设计天线的工作频带范围为2.27~2.73GHz,端口隔离度在31dB以上。同时,单极结构辐射元主极化要比其交叉极化大25dB以上,环形结构辐射元在较大空间范围内其主极化比交叉极化大23dB以上。这表明所设计双馈双极化天线具有较高的端口隔离度,且有良好的极化纯度。通过结构参数调整,还可望同时覆盖5.8GHz频段,以满足IEEE802.11n标准要求。     

一种新型Ku频段宽带高增益双极化微带天线阵列

介绍了一种新型的Ku频段宽带高增益双极化微带贴片单元及96元阵列的设计。设计中单元采用层叠贴片天线结构,提高了单元的带宽和增益,两个极化端口采用分层馈电,其中水平极化端口采用共面馈电,垂直极化端口采用探针背馈。在馈电网络的设计中引入反向馈电技术,降低了交叉极化。仿真与实测结果表明:该阵列增益达到了26dBi,口径效率约为51%,交叉极化电平小于-30dB,水平极化端口相对阻抗带宽达11.3%,垂直极化端口相对阻抗带宽达13.7%,两端口隔离度高于40dB.     

Ku 波段全口径高隔离度双极化阵列天线的研究

本文提出并设计制作了一种新型的全口径高隔离度双极化单脉冲阵列天线。该阵列天线单元采用微带贴片与喇叭复合的形式,将微带贴片作为喇叭的二次激励源,以获得更高的单元增益。其中的微带贴片采用一对相互垂直的带状线通过两个呈“T”型分布的“H”形缝隙耦合馈电,以获得较高的极化隔离度（在工作频带内小于-35dB）。在阵列馈电设计中采用二次错位倒相技术,进一步改善了极化隔离度和交叉极化。仿真和实测结果表明,在f0±200MHz 内,驻波比小于2,垂直极化增益大于27dB,水平极化增益大于27.5dB,端口极化隔离度小于-40dB,和差端口隔离度小于-28dB。     

一种新型宽带双极化微带贴片天线的设计

摘要：运用口径耦合理论、腔模理论、反相馈电技术和多层贴片结构设计出一种新型的P波段（中心频率为0．75GHz）宽带双极化微带贴片天线。天线的两个极化端口采用共面馈电;馈电网络设计中采用短路耦合线实现反相馈电。仿真结果表明该天线两个极化端口实际增益均达到8．5dB,水平极化端口在0．64-0．85GHz频率范围内驻波比小于2,相对带宽为28％;垂直极化端口在0．68-0．85GHz频率范围内驻波比小于2,相对带宽为22．6％,两端口隔离度高于53dB。     

超表面加载极化可重构双极化微带天线设计

基于超表面结构设计了一种2.555~2.655 GHz频段的极化可重构双极化微带天线。首先根据微带天线理论设计了缝隙耦合正交馈电的双极化微带贴片天线,然后提出并设计了一种方形切角的新型超表面结构,并将该超表面放置在双极化微带天线上,通过机械方式旋转超表面,实现了左、右旋圆极化和水平、垂直线极化之间的极化转换。利用HFSS仿真软件对该超表面加载微带双极化天线进行了仿真。结果表明,该双极化天线能够便捷地实现极化转换,且在两种极化状态下,天线在工作频带内的回波损耗小于–10 dB,隔离度大于20 dB,圆极化工作状态下的轴比小于3 dB,天线的整体性能良好。     

高隔离度双极化微带贴片天线的设计

对双极化方形微带贴片天线端口之间的隔离作了理论与实验研究.基于腔模理论,直观地分析了高次模的激励影响单元两极化端口之间的隔离,并解释了反相馈电抑制其端口耦合的原理.设计、加工了一种新型的双极化微带贴片单元,理论仿真与实验测试结果吻合得很好,证实了应用该方法可使单元两极化端口间的隔离度提高约10～20dB.     

一种可用于5G点对点通信的宽频双极化阵列天线

本文设计了一款高增益宽频双极化天线。该天线采用多层辐射贴片的结构，拓展天线的带宽，并用一对正交分布的微带线直接馈电在辐射贴片上，增强天线极化隔离度，形成双极化特性。通过设计馈电网络，组成阵列后实现良好的带宽与定向辐射特性，并且具有良好的端口隔离度和辐射极化纯度。实测结果表明，小于-10dB的阻抗带宽为18.18%(5.0～6.0GHz),带内平均增益为15.5dBi,全频段端口隔离度小于-30dB,主瓣方向上的主极化电平与交叉极化电平相差40dB,带内增益波动小于3dB,具有良好的增益平坦度。该天线适合作为5G通信系统中的天线单元，具有实用价值。     

一种高隔离度的双极化微带天线阵的理论和实验

本文提出利用双端口的串行角馈方形帖片实现双极化,并设计了一种共面的双极化馈线网络,综合运用多端口网络模型、腔模理论和分片法,给出了单口双端口天线单元和双极化天线阵列的理论分析。本文法计算简单便,适合于工程应用,实际设计了一副６ＧＨｚ频段的背地里层天线阵,实验测量的双端口隔离度达－４１ｄＢ,其性能明显优于通常的单层双极化微带天线阵,该面阵结构简单、馈线网络较小,且易合并成更大规模的双极化瑚线阵。     

一种新型极化捷变有源微带天线阵

本文提出了一种新颖的极化捷变放大器型有源微带天线阵,只要在馈电端电控单一有源电路就能实现整个微带天线面阵极化的捷变和信号的放大.利用角馈方形微带贴片设计了一副具有高隔离度和低交叉极化的新颖16元双极化面阵,并分析了天线阵的共极化和交叉极化方向图.介绍了有源电路的设计.该电路利用一专用电控移相器,通过改变场效应管(FET)栅极的直流控制电压,电控两极化端口间的0°或90°相差,实现天线阵由线极化到圆极化的捷变.低噪声放大器(LNA)不仅使有源天线增益提高12-14dB,而且改善了天线的驻波比带宽和隔离度.文中给出了无源双极化阵和有源阵的实验结果,证实了理论的有效性.     

双频段双极化共孔径阵列馈源反射面天线设计

介绍了一种新型Ku/Ka双频段双极化共孔径阵列馈源偏馈抛物柱反射面天线的设计。在双频段双极化共孔径阵列馈源设计中,Ka波段采用裂缝波导阵,并且位于共孔径馈源阵列的下层,双极化Ku波段采用微带贴片天线、位于共孔径阵列馈源的上层。文中给出了该双频段双极化共孔径阵列馈源的设计及测试结果,并将该测试结果代入偏馈抛物柱反射面天线中在FEKO软件平台上进行了半实物仿真,仿真结果表明,该双频段双极化共孔径阵列馈源偏馈抛物柱反射天线实现了如下设计目标:Ku波段双极化水平面扫描范围为±17°,两个主面副瓣电平优于-30dB,Ka波段水平面扫描范围为±10°,两个主面的副瓣电平优于-30dB,双频段双极化两个主面的波瓣宽度和波束指向完全匹配。     

A quad-polarization and frequency reconfigurable square ring slot loaded microstrip patch antenna for WLAN applications

In this paper, a novel polarization and frequency reconfigurable microstrip patch antenna which can switch between vertical and horizontal linear polarizations, left hand and right hand circular polarizations at two WLAN frequencies is presented. The orthogonal linear polarizations are achieved by a square microstrip patch antenna fed by two ports on adjacent sides. By introducing corner truncated perturbation on opposite corners of right diagonal of a square patch, orthogonal circular polarizations are achieved. By controlling the bias voltage of two PIN diodes loaded at perturbed corners, a single structure can achieve quad polarization states. Furthermore, by superimposing a square ring slot into the corner truncated square patch and incorporating four PIN diodes into the square ring slot, quad polarization are achieved at dual frequencies. Simulated and measured results indicate that the antenna can achieve quad polarization at two WLAN bands (5.15–5.35 GHz) and (5.75–5.85 GHz). The proposed antenna is simple, has low profile and can be scaled easily for other frequencies.     

Single-Fed Microstrip Patch Antenna With Switchable Polarization

A single-fed reconfigurable microstrip antenna that can provide various polarization diversities is presented in this paper. The antenna is excited by a microstrip feed line through aperture coupling. When two PIN diodes are used to respectively reconfigure the coupling slot and the open stub of the feed line, the polarization of the microstrip antenna can be switched between vertical and horizontal polarizations. For the reconfigurable antenna with the linear polarization diversity, it can be converted to a circularly-polarized antenna with switchable polarization sense by introducing a perturbation segment. Moreover, an antenna with the quadri-polarization diversity, including dual orthogonal linear polarizations and two circular polarizations, is also developed from the structure of the switchable circular polarization microstrip antenna, and only three diodes are required. Details of the antenna design are shown, and the measured results for the constructed prototype are also exhibited and discussed.     

极化轨道约束下的最优极化（三）

本文研究了极化测量过程中的信号增强问题,提出利用信号干扰功率差（ＰＤＳＩ）作为优化目标函数,以改善恶劣电磁环境中的信号接收质量。文中求解了以ＰＤＳＩ作为目标函数时的全局最优极化以及极化轨道约束下的局部最优极化,并给出最优极化对改善信号接收效果以及极化轨道对于改善信号接收效果有效度的定量描述。     

宽带极化与方向图可重构天线研究

随着无线通信系统的快速发展, 宽带可重构天线将在未来发挥巨大作用.文中综述了四种宽带极化与方向图可重构天线, 它们都具有提高通信系统容量, 消除极化失配, 扩大辐射范围等特点.首先介绍了一种宽带的多线极化可重构天线.此款天线基于L型探针馈电的贴片天线, 实现了0°, 45°, 90°以及—45°极化的选择, 具有宽带、低剖面、高增益的特点.其次, 同样基于L型探针馈电的贴片天线, 通过引入一个输出相位可重构的功分馈电网络, 实现了宽带的圆极化可重构天线, 其同样具有宽带、低剖面、高增益的特点.除了极化可重构天线, 文中还介绍了两款方向图可重构天线, 可分别实现线极化以及圆极化的全向锥状波束以及定向辐射波束的方向图可重构.前者是基于宽带的单极子贴片天线跟L型探针馈电的贴片天线的有机结合.后者是基于环缝隙的贴片天线配合激励端口可重构的功分馈电网络的组合.此两款天线均具有结构紧凑、宽带、增益稳定的特点.     

A Corner‐Fed Microstrip Circular Antenna with Switchable Polarization

In this paper, a design for a novel microstrip antenna with circular polarization diversity is proposed and experimentally investigated. This antenna is excited by a microstrip line, which is located at the corner of a circular patch. The polarization state can be switched electrically by setting a diode to on or off. The novel structure we describe here enables the optimization of the input match for both polarizations. From the measured result, good axial ratios are observed at the operating frequencies.     

天线特性测量中极化基失配的影响及校准

对一部待测、待评估的天线,其交叉极化特性实际上是依赖于极化基的,极化基匹配或失配情况下,得到的交叉极化性能评估结果也不一样.文中首先建立了天线极化特性测最模型,推导了交叉极化测量校准约束模型,给出了该约束下的最佳收发极化基.并针对实际的雷达天线进行了外场测量实验,实测处理结果验证了上述结论.利用约束模型可对实测的极化方向图实现有效的校准.     

基于雷达辅阵的自卫压制式干扰极化对消方法研究

本文探讨了利用雷达主天线和辅助天线极化特性的差异来抑制自卫压制式干扰的可行性.首先给出了目标和干扰在主、辅天线接收通道的信号模型,而后建立了自卫压制式干扰的极化对消模型,提出了利用对消前后信号干扰噪声比(SINR)的变化来综合评价对消算法的性能.最后,具体分析了主辅天线极化正交和匹配两种极端情况下对消算法的性能,给出了一组有意义的结论,突破了常规将雷达辅助天线仅用于旁瓣对消的观念.     

天线极化特性的近场测量技术

针对天线极化特性如何在近场测量系统进行测试的问题,文中从实际工程应用出发,结合电磁场理论,基于椭圆极化波的分解理论,提出了利用线极化探头测量椭圆极化天线特性参数的方法。通过线极化探头进行两次正交的测量即可得到圆极化天线的方向图、轴比、倾角、增益等特性信息,也得到了线极化天线的交叉极化特性。     

极化轨道约束下的最优极化（一）

本文针对极化测量过程中干扰和噪声对接收效果的影响，提出一种极化轨道约束下的变极化接收方法，以改卷接收系统的SINR（信号干扰噪声比）。在极化轨道约束下的SINR最大化问题是一个寻求局部最优的问题，本文在任意的信号与干扰极化条件下，解决了任意给定的极化轨道上SINR的最大化问题，并对极化轨迈上最优极化与其他两种最优极化得到的SINR进行了比较。     

The theory and measurement of noncoherent microwave scattering parameters

The theories of observation and measurement of the average noncoherent scattering parameters for expansive scenes are developed and interpreted. The theory identifies all the scattering parameters and in this regard introduces three scattering coefficients not previously defined. The result is compared with the theory for coherent targets and a unique feature is identified. This feature, induced by spatial averaging, enables the theory to admit partially polarized returns. Intensity (power) and correlation techniques similar to that for coherent targets are proposed to measure all the scattering parameters. The sensitivity of the intensity technique to various practical realizations of the antenna polarization requirements is presented by means of computer simulated measurements. The simulations were conducted with a scattering characteristic similar to that of the sea. However, these results with the help of the theory axe easily extended to other characteristics. It is shown that careful adherence to the antenna polarization specifications is required to measure the weaker scattering parameters. In the case of the weaker parameters the complete antenna polarization property including the amplitude and relative phase of the orthogonal polarizations must be documented to validate the measurement. The results of this paper are useful for specifying radar scatterometer antennas, for designing meaningful noncoherent scattering experiments and for interpreting the character of scatterometer returns.