設計加入集總式元件的微小化蕈狀式結構並使用此蕈狀式結構來加強小天線的輻射效率

Abstract

在此論文中，我們希望以一個簡單且明瞭的方式來設計出微小化的蕈狀結構，因此我們將利用集總是元件來達成製作微小化蕈狀結構，而不是利用複雜的電路方式例如指叉式電容和狀蛇行線。 此微小化的蕈狀結構設計主要是利用集總式元件使其本身的電磁間隙能夠往低頻移動，我們可以利用傳輸線的觀念來解釋當一系統本身加入更多的電容電感的效應後，其操作頻率會受到電容電感的影響而產生在較低頻的範圍，進而達成微小化的目標。 在本論文中，我們將以三種方式來分析微小化蕈狀結構，第一種是利用色散圖來分析，此方法的優點是他是一個完整的分析模型可以準確的判斷出電磁間隙的所在頻段，第二種是利用散射參數來分析，此方法是能夠以實驗方式來觀察電磁間隙，第三種則是改良式的等效電路模型，他將會以比前兩種方法都還要快的速度來分析此微小化蕈狀結構。此外我們還會再設計出兩種天線：貼片天線以及複合式左右手微小化天線，其操作頻率均會在微小化蕈狀結構的電磁間隙中，用來印證此微小化蕈狀結構能夠使天線輻射效率加以提升。

In Thesis, the new type of compact mushroom structure had been proposed. The original equivalent circuit transmission line model tells that the electromagnetic bandgap (EBG) range can be affected by its equivalent capacitor and inductor. So this thesis propose the simple way to shift down the EBG range by inserting lunped element, instead of complex design, such as interdigital capacitor and meander line. Also we use three methods to analyze the compact mushroom structure, dispersion diagram, S-parameters measurement, and modified equivalent circuit model. Three of them have different advantage for analyzing. Dispersion diagram provides the complete analysis for compact mushroom structures, S-parameter measurement is the only way to observe the effects of EBG practically, and modified equivalent circuit model have the quicker way to find out the bandgap range. In addition, patch antenna and CRLH small antenna are designed to combine with compact mushroom structure, to prove that the radiation efficiency of both antenna can be improved by compact mushroom structure.