基於類蕈狀結構之小型三頻雙模態微帶天線

Abstract

本論文提出了微帶天線結合類蕈狀結構的天線，類蕈狀結構是由傳統蕈狀結在上面挖兩個L型溝槽所組成，這種複合式左右手的結構可以產生零階與正一階共振。這個天線具有兩種輻射場型，一種是零階共振產生的全向性偶極天線場型，另一為正一階共振產生的指向性微帶天線場型。一般來說複合式左右手傳輸線的正負一階的共振頻率受限於單元個數，導致固定單元數時，共振頻率難以設計。本論文所用的類蕈狀結構天線為單一單元，且可以藉由調整兩個L型溝槽的間距來調整正一階的共振頻率。 我們提出的天線結合了下層的類蕈狀結構和上層的微帶矩形金屬，中間夾了一層空氣層。當類蕈狀結構結合堆疊天線時，產生了三頻的特性，且可藉由調整最上層微帶金屬的大小來單獨改變第三共振頻率，天線操作在2.31 GHzヽ2.92 GHzヽ 3.7GHz，第一個頻率為零階共振頻率，第二為正一階共振頻率，最後是第三共振頻率。我們的天線具有許多優點，像是小型ヽ三頻ヽ雙共振模態ヽ頻率可調性，使得天線有更多的應用性。

In this paper, a microstrip patch antenna loaded with mushroom-like structure is presented. Mushroom-like structure is composed of a mushroom with two L-shaped slots. This composite right/left-handed (CRLH) structure can excite zeroth-order res-onance (ZOR) and first-positive-order resonance (FPOR). This antenna has dual mode pattern includes monopolar and patch-like radiation pattern. ZOR frequency generates monopolar radiation pattern, FPOR generates patch-like radiation pattern. Generally speaking, FPOR frequency and first- negative-order resonance (FNOR) are restricted to the number of unit cells. Once the number of the unit cells is decided, the FPOR frequency cannot be adjusted. The first order resonance frequency of our proposed antenna can be adjusted by varying spacing of two L-shaped slot so that the FPOR frequency can be reduced. Proposed antenna consists of mushroom-like structure in the bottom and top mi-crostrip patch, and air layer is between twos substrates. As microstrip patch stacked with mushroom-like structure, antenna revealed triple-band behavior, and the third frequency can be determined by top patch size. Antenna is working in 2.31 GHz, 2.92 GHz, 3.7GHz.