扇形波束合成與可切換波束之單一導體洩漏波天線陣列

Abstract

一般的洩漏波天線具有寬頻、高增益、高指向性等優點，且大多數具有頻率掃描的功能，但由於單一導體洩漏波天線沒有實際的地，使得輻射場型固定在end-fire方向，因此我們利用此特性，以扇形排列天線陣列，造成扇狀輻射場型，又同時保有寬頻、高增益，及場型在end-fire方向等優點，最後，本論文並以天線陣列理論為基礎，提出一個可快速概估場型的合成法，當適當改變其扇形天線陣列之半徑與間隔角度，我們可得剪裁出所欲求得之半功率波束寬。 一般波束切換型智慧天線，其切換波束需不隨頻率改變，符合單一導體帶狀洩漏波天線之主波束特性，因此我們在本論文中設計兩組切換型智慧天線，每組分別由四個相同的單一導體帶狀洩漏波天線陣列擺置於四個不同的方位所構成，對於第一組與第二組天線，其陣列之半功率波束寬角度分別為23°與50°，再搭配本文中所製作之一對四射頻開關(SP4T switch)則可切換個別陣列之主波束，使得一、二組天線切換角度涵蓋範圍各為92°與200°。其他天線相關的數據、模擬與量測值也將會表現在本文中。

Ordinary leaky wave antenna has the advantages of broadband, high gain, and high directivity. Also, most of them have the function of frequency scanning. However, since single conductor leaky wave antenna is without actual ground, the radiation pattern is fixed in the end-fire direction. Thus, by making use of this characteristic, we arrange a fan-shaped antenna array, which results in sector radiation pattern while preserving the strengths of broadband, high gain, and end-fire radiation pattern. Finally, we present an efficient method to synthesize radiation patterns based on the antenna array theory. By changing the radius and spacing angle of fan-shaped antenna array appropriately, we can mold and obtain the desired half-power beamwidth of this antenna. Generally, the beam of beam-switched smart antenna does not change with frequency, which fits the nature of the mainbeam of single conductor leaky wave antenna. Therefore, we design two sets of smart antenna. Both are formed with four identical single conductor leaky wave fan-shaped antenna arrays placed in four different directions. The half-power beamwidth of the first and the second antenna array are 23°and 50° respectively. After adding a pair of SP4T switch, which we designed, we are able to switch the main beam of each array, which will allow the first and the second antenna arrays to cover a range of angle of 92° and 200° respectively. Related statistics, stimulation and the values of measurement will be presented.