印刷式對數週期天線與超寬頻功率分配平衡器之整合設計

Abstract

本論文旨在設計超寬頻對數周期天線與超寬頻平衡器電路，以整合成超寬頻線性極化天線。對數週期天線屬於非頻變天線的一種，具有線性極化與平穩的增益場型等特性。此類天線需額外設計超寬頻平衡器以連接天線端與不平衡饋入端，使其系統及場型及增益穩定，天線操作頻帶得以拓展。 文中平衡器之設計部分，分析傳統Marchand Balun之工作原理並將之轉化為等效傳輸線電路，實踐架構平面化。運用平面式印刷電路技術製作，模擬及量測平衡器之操作頻帶落在0.8 GHz至9.7 GHz (比值為12:1)。本文設計兩個版本天線，第一個輻射場型為端射，與文中設計之平衡器做整合後，模擬及量測之增益值在0.8 GHz至8 GHz皆高於3 dBi (比值為10:1)；而另一天線則產生寬邊輻射場型，與設計之平衡器整合後在0.8 GHz至10.5 GHz之增益值皆落在3 dBi 以上(比值13:1)。

This thesis is about the design of both ultra-wideband log periodic antennas and the balance feeding network, which can be integrated together. A frequency independent antenna generates stable radiation patterns throughout the entire operating band. However, when feeding with an unbalance circuit, this kind of antennas has negative impact like gain-dropping, tilting patterns, or even making the system unstable. In this article, we designed and implementation a planarization balun which operates from 0.8 GHz to 9.7 GHz (ratio = 12:1). Two proposed antennas are design and integrated with the proposed balun. The first integrated antenna design generates endfire patterns with realized gain better than 3 dBi from 0.8 GHz to 8 GHz (ratio=10:1). The other integrated antenna design generates broadside patterns with realized gain better than 3dBi from 0.8 GHz to 10.5 GHz (ratio=13:1).