寬頻緩變半寬微帶洩漏波天線陣列

Abstract

本論文設計一天線陣列，應用寬頻緩變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)簡單的饋入結構，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，本文使用一演算法來設計寬頻緩變半寬微帶洩漏波天線陣列。而由此寬頻緩變半寬微帶洩漏波天線的量測結果，可以看到設計的頻寬從14 GHz到30 GHz反射損耗皆小於-10 dB，其相對頻寬約2.3 : 1。 本論文後面提出一新穎演算法，來改善寬頻緩變半寬微帶洩漏波天線的高頻輻射場型。最後根據天線量測結果，可以看到設計的頻寬從14 GHz到30 GHz反射損耗皆小於-10 dB(相對頻寬約2.3 : 1)，且有效改善先前高頻場型可能造成的分岔現象，實現一輻射場型於高頻時圓滑集中的頻緩變半寬微帶洩漏波天線陣列。

In this thesis, we used the broadband tapered half-width microstrip leaky-wave antenna as the unit element to design a four-element antenna array. The half-width structure is used to simplify the conventional feeding structure. In the half-width structure, the perfect electric conductor (PEC) wall is realized by via holes connecting 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; and (IV) less coupling between array element. Based on the characteristics of the first higher order leaky-mode for the microstrip antenna, this thesis proposed a scheme for the empirical design of broadband tapered half-width microstrip leaky-wave antenna array. The measured bandwidth of the antenna has a return loss less than -10 dB from 14 GHz to 30 GHz, yielding a relative bandwidth of 2.3 : 1. In this thesis, we also proposed a novel design scheme for the empirical design of broadband tapered half-width microstrip leaky-wave antenna array to improve the radiation patterns in higher frequency. The measured bandwidth of the antenna has a return loss less than -10 dB from 14 GHz to 30 GHz(relative bandwidth of 2.3 : 1), and the main beam bifurcation in the previous design was alleviated.