一种新型、高效、双极化的平板阵列

A Novel High Efficiency, Dual Polarised, Flat Plate Array

随着对阵列天线应用的增加 ,低剖面、高性能、重量轻的阵列的设计引起了人们广泛的兴趣。在这篇文章中 ,我们描述了一个平板阵列的开发 ,它是由 ERA公司的 ESA资助下开发出来的 ,其目的是提供一个最终可工作于太空中的 Ku波段的双线性极化天线。关键的性能要求是要有类似于普通的喇叭天线的交叉极化水平 ,并且要效率高。经过对可能的阵列单元和馈线系统详细的研究 ,构造出一个用小波导口径组成的阵列原型 ,设计的小波导口径利用相互耦合的作用使口径效率提高了 81%以上 ,是普通喇叭天线所预期的最大值。口径是通过一对低损耗、悬吊的带状线网络给一个 8× 12的单元阵列提供均匀激励来馈电的 ,网络一个在一个后面放置 ,用一个普通的短路电路使它们相互匹配。阵列由 2× 2的子阵列组成 ,每一个子阵列采用一种新型几何形状的馈源构成 ,以抵消馈源探针之间的交叉耦合 ,阵列的总厚度大约是一个 λ。原型天线经过特性检测 ,取得了很好的效果 ,在主波束 - 1d B点范围内两端口的交叉极化辐射低于 35 d B,端口与端口之间的隔离度低于 6 0 d B。同极辐射方向图显示了非常易于控制的响应 ,测得的效率约为 80 %。若不考虑馈源大约 0 .5 d B的损耗 ,阵列的口径效率大约为 95 %。

With the increasing use of array antennas in many applications, the design of low profile, high performance, ligntweight arrays is of considerable interest. In this paper, we describe a flat plate array development which has been carried out at ERA Technology under ESA funding, the aim of which has been to provide an ultimately space qualifiable, dual linearly polarised antenna operating at Ku-Band. The key performance requirements were cross-polarisation levels similar to conventional horn antennas, and high efficiency. After a detailed study of potential array elements and feed networks, a prototype array has been constructed using small waveguide apertures. The small waveguide apertures are designed so that mutual coupling effects increase the aperture efficiency above 81%, the maximum value expected from a conventional horn. The apertures are probe-fed using a pair of low-loss suspended stripline networks providing uniform excitation to the 8×12 element array. The networks are placed one behind the other and use a common short circuit for matching purposes. The array is composed of 2×2 subarrays, each configured using a novel feed geometry to cancel cross coupling between feed probes. The overall array thickness is about 1λ. The prototype antenna has been characterised and very good results have been achieved. Cross-polarised radiation from both ports is below 35dB within the -1dB points of the main lobes and port-to-port isolation is below 60dB. Co-polar radiation patterns show very well-controlled responses and have a measured efficiency of about 80%. When feed losses estimated at 0.5dB are excluded, the aperture effciency of the array is found to be approximately 95%.