多耦合槽孔饋入微帶洩漏波天線之應用

Abstract

本論文設計天線皆使用耦合槽孔饋入來取代傳統180度相位差激發電路之饋入結構，此饋入的微帶線與天線在不同層的基板，可以做到個別最佳化電路設計，且中間的接地面可以消除饋入和匹配網絡產生的寄生場型，使上方微帶洩漏波天線的場型減少干擾變得更準確。 根據微帶線第一高階洩漏波特性，本論文使用電路設計模擬軟體與全波仿真模擬軟體來設計饋入網絡的功率分配器與提出的天線架構。提出的第一支天線為多耦合槽孔饋入之微帶洩漏波天線，藉由同相位激發使天線上電流分布均勻提高天線增益與獲得較好的指向性。側邊多耦合槽孔饋入之微帶洩漏波天線的增益只比側邊單耦合槽孔饋入之天線增加0.2 dB，而中間多耦合槽孔饋入的微帶洩漏波天線增益比單耦合槽孔饋入的天線增益增加了3 dB；另一支天線則是將饋入與微帶洩漏波天線皆做陣列設計，使天線上電流分布更加均勻，與傳統貼片天線陣列相比具有低耦合與主波束高增益集中之效果。

In this thesis, we use aperture-coupled feeding structure instead of conventional complex feeding structure to design leaky-wave antennas. The feeding circuit and the antenna are realized on different layers of the substrate, and can be optimized respectively; the ground plane serves to eliminate the spurious radiation from the feeding and matching networks. Thus it would not contaminate the radiation pattern. Based on the characteristics of the first higher leaky-mode for the microstrip antenna, this thesis proposes the feeding network composed of power dividers to design leaky-wave antennas. The feeding network and microstrip leaky-wave antennas are simulated by commercial software. The proposed antennas with this feeding structure can improve gain and directivity by exciting in-phase signal. It makes uniform current distribution on the antenna. The gain of multiple edge-fed aperture-coupled microstrip leaky-wave antenna is only 0.2 dB more than single edge-fed one. Compared with single center-fed aperture-coupled microstrip leaky-wave antenna, the multiple center-fed one has gain enhancement of 3 dB. Besides, we combine feeding array and microstrip leaky-wave array to improve the current distribution in antenna. It makes main beam more concentrated and has less coupling effect than conventional patch array.