本論文主要研究車用行動通訊天線，包括傳統的車用FM單偶極天線與車用無線通訊平面倒F天線(planar inverted-F antennas，PIFAs)，並了解車體結構對天線輻射場型所造成之影響。基於現有量測設備考量，論文中採用電性尺度(electrical dimension)相同之縮小車體模型及天線進行相關研究。首先透過操作在FM頻帶之車用四分之ㄧ波長單偶極天線，研究天線與車頂夾角及天線放置位置對輻射場型造成的影響。接下來基於汽車整體美觀與流線性之考量，研製一低姿態(low profile)雙頻PIFA，並分析車體對該天線輻射場型所造成之影響。此外，利用兩個雙頻PIFA，研製可四頻操作之組合式PIFA天線，此種設計可提供設計人員較高的自由度。最後透過coupled-line 180° hybrid coupler，改良原本四頻組合式PIFA天線雙埠饋入之方式，達成單埠饋入之目的。 The study on two types of car antennas, including car monopole antennas for radio reception and car planar inverted-F antennas (PIFAs) for wireless communication, and the impact of the car body on their radiation characteristics are presented in this thesis. For measurement facility consideration, the interaction between the antennas and car are analyzed and measured using the models of equivalent electrical dimensions. In this thesis, the impact of the car body on the performance of a car monopole antenna is studied first. To be more specific, the antenna parameters associated with the antenna location and the angle between the antenna axis and the car roof are systematically analyzed. Next, a low profile dual-band PIFA is proposed, and its radiation characteristics on a car roof is presented. Also, a quad-band combination PIFA consisting of two dual-band PIFAs are demonstrated. Finally, the change of feeding structure of the quad-band PIFA via a coupled-line 180° hybrid coupler is presented.
