Dual Circularly Polarized Patch Antenna for Polarization Diversity Applications

本論文提出了一個應用於無線通信統之俱極化分集雙圓極化微帶天線。我們所提出的天線設計具有結構簡單並且易於製造的特性。藉由截角的方式產生圓極化。將兩矩形微帶天線擺放在垂直位置，則可改變截角位置來產生左手圓極化和右手圓極化。 此外，為了增加兩微帶天線間的隔離度，在天線之間擺放了一條帶狀金屬。量測結果顯示隔離度大概增加了3~4 dB。然而頻寬受到帶狀金屬的影響而略微下降且圓極化亦受到干擾。此方法沒有改變天線外型。保持天線結構較為簡單並且易於製造的優勢。 以上所提出之設計過程及天線架構之模擬與實驗驗證，於本論文中都會完整的探討。A dual circularly polarized patch antenna with polarization diversity is proposed for wireless communication applications. The proposed antenna has a simple structure and is easy to fabricate. The circular polarization can be obtained by truncating the corners at the square patch. The two patch antennas are placed perpendicular to each other, then the position of the truncated corner can be changed to generate the left hand and right hand circularly polarized circular polarizations. In order to increase the isolation between the two patches, a strip is placed between the two patches. The isolation is then increased by about 3 – 4 dB in the measurement result. Because of the strip, the impedance bandwidth is slight decreased slightly, and the circular polarization is also interfered. This method does not change the antenna structure, and the proposed antenna still has a simple structure and is easy to fabricate. Details of the antenna design are discussed. Experimental and simulated results are also presented and discussed.口試委員會審定書 i 誌謝 ii 中文摘要 iii ABSTRACT iv CONTENTS v LIST OF FIGURES vii LIST OF TABLES x Chapter 1 Introduction 1 1.1 Motivation 1 1.2 Literature survey 2 1.3 Chapter outlines 4 Chapter 2 2.4 GHz Dual Circularly Polarized Patch Antenna Fed by Microstrip Lines 10 2.1 Preview of Circular Polarization Theory 10 2.2 Antenna Structure 11 2.3 Experimental and Simulation results 12 Chapter 3 2.4 GHz Dual Circularly Polarized Patch Antenna with a strip Fed by Microstrip Lines for improving isolation 32 3.1 Antenna Structure 32 3.2 Experimental and Simulation results 33 Chapter 4 Conclusion 49 REFERENCE 5