寬頻緩變半寬縮短化微帶洩漏波天線陣列與調變式週期性鉚釘結構控制傳播特性之半寬微帶洩漏波天線陣列

Abstract

本論文設計之天線陣列應用寬頻半寬微帶洩漏波天線作為天線陣列之單位元素。我們使用半寬的天線結構來簡化傳統複雜的180度相位差激發電路。半寬電路結構利用鉚釘使基板上下層金屬導通並作為等效電牆，其優點有: (I)簡易的饋入結構，僅需使用微帶線直接饋入；(II)可準確激發純正的第一高階模，而不須抑制零階模；(III)相較於全寬電路有較小體積；(IV)於天線陣列設計上有較小的耦合現象。 根據微帶線第一高階洩漏波特性，本文使用數值設計流程與全波仿真模擬軟體來設計天線。而由此天線的量測結果，可以看到設計後的縮短長度尺寸微帶洩漏波天線陣列頻寬由6.5 GHz到30 GHz反射損耗皆小於-10 dB，其相對頻寬約4.29 : 1，而具有週期性鉚釘結構控制傳播特性之微帶洩漏波天線陣列頻寬由11 GHz到13 GHz，且實現了降低旁波瓣與光柵波瓣之增益，以及主波束高增益集中之效果。 本論文後面提出一新穎的耦合模態結構來優化週期性鉚釘結構控制傳播特性之微帶洩漏波天線陣列的頻寬。最後根據天線的量測結果，我們改良了原有天線的頻寬，其成功增加了2 GHz左右的操作頻帶。

In this thesis, we use the broadband tapered half-width microstrip leaky-wave antenna to be the unit element and design an eight element antenna array. We use the half-width structure to simplify the conventional feeding structure, which is 180°out of phase. In the half-width structure, the PEC wall is constructed by via holes conducting the two metallic layers on substrate. The advantages of this structure are: (I) simple feeding structure fed by microstrip line ; (II) pure mode excitation and no need to suppress mode ; (III) reduced size as compared to the full-width structure ; (IV) less interaction in an array design. Based on the characteristics of the first higher order leaky-mode for the microstrip antenna, this thesis proposes a scheme for the empirical design of half-width microstrip leaky-wave antenna arrays . The measured bandwidth of the antenna has a return loss less than -10 dB from 6.5 GHz to 30 GHz, yielding a relative band width of 4.29 : 1. In this thesis, we also propose a novel coupled-mode scheme for the empirical design of half-width microstrip leaky-wave antenna arrays with varying periodic vias to control the propagation characteristics optimization of bandwidth. Based on the measurement results, we realize a bandwidth of 2 GHz in previously antenna array.