應用在極化掃描之數種天線設計

Abstract

本論文著重在極化槽孔耦合天線之設計。在無線通訊系統中，為了克服在高度多路徑散射環境下訊號在接收端所產生的衰減的問題，極化掃描技術可說是非常好的改良方法，不但可以有效地抑制衰減效果，更能達成頻率重複使用的特性。但現有的論文研究多數侷限於單一頻段或是單一極化特性之設計，而本篇論文第一個主題便是將數種不同共振頻段的極化天線整合在單一系統機殼中，而讓彼此輸入埠不會有過強的訊號耦合和每個天線能在各個頻段有好的操作特性。第二個研究主題為因應整合型通訊系統的發展迅速與極化掃描技術的需求，乃利用PIN二極體應用於微帶天線以及槽孔耦合天線上，並藉由著不同的設計方法，提出利用單一天線即可以操作於雙圓極化以及雙線性極化輻射的設計方式。設計出來的天線不但尺寸適中，更有良好的天線輻射特性，適合應用在無線區域網路和多埠輸入多埠輸出通訊系統中的極化天掃描領域。

The thesis lays great stress on the design of the aperture-coupled polarized antenna. Polarization diversity is the most effective technique to improve the fading loss which was generated in the multi-path environment. It not only avoids the fading loss but also realizes frequency reuse due to its useful polarization modulation scheme. But nowadays research is restricted to only single frequency design or single polarization state design. In this thesis, the first topic focuses on integrating several polarized-antennas with different operating frequencies into a system unit, while they can co-work well in each operating frequency without excess coupling. In the second topic, the concept of the novel reconfigurable quadri-polarization diversity patch antenna is proposed. By using pin-diodes to switch different polarization states, the proposed antennas provide a pair of orthogonal linear polarizations and a pair of orthogonal circular polarizations. The proposed antennas not only have a medium dimension but also provide good radiation performance. Therefore, the novel reconfigurable antennas would be good potential candidates for future polarization diversity applications in WLAN and MIMO communication systems.