串列饋入式陣列天線之研製

Abstract

本論文主要是探討串列饋入式陣列天線製作的方法和必需克服的問題，在論文中製作了二種陣列天線，分別應用於12.5GHz衛星接收的頻段，和10.5GHz測速雷達上；在第一個部份使用了一分三的功率分配器，分別饋入三組的子陣列中，每個子陣列中有四個經過功率分配的隙孔耦合天線(aperture coupled antenna)，其目的要增加旁束波程度(side-lobe level)，然而一分三的功率分配器的相位的設計是造成旁束波程度好壞的主因。 在第二個部份使用的是串列行波饋入式的(Series-fed traveling wave microstrip array antenna) 微帶陣列天線，陣列天線的上方加入了指向器(Director)來增加天線的增益和頻寬，由於使用串列饋入的方式，若饋入線阻抗相同，天線數量增多，將造成功率分配不均，使得天線的增益嚴重的下降，為了能更清楚的從量測中看到這個現象，利用16個天線陣列，去比較饋入線的不同所產生的效果，使用一段式饋入，特性阻抗分別為25歐姆、40歐姆和70歐姆，另一個為二段式饋入，將饋入線分成25歐姆和40歐姆，二段分別饋入到8個天線陣列，比較了功率分佈和增益大小，如預期是使用了二段式饋入天線在各方面都優於一段式饋入天線。

This thesis discussed manufacture method and study of series-feed array antenna, and also studied must get through issue. I fabricated two kinds of array antenna and applied different frequency range in the 10.5GHz and 12.5GHz.The fist part in this thesis, the aperture coupled array antenna was compose of 12 element antennas and utilizing power divider divided 12 element antennas into 3 sub-elements. There were 4 element antennas in each sub-element. These sub- elements utilized power divider method to make the side-lobe level decrease. However, the power divider phase design was principal cause of side lobe level performance.

The second part in this thesis used the multilayer construction. Top layer used the director to increase radiation gain and bandwidth. Bottom layer used the series-fed traveling wave microstrip array antenna. This construction will bring low radiation gain which was cause of each antenna power distribution non- uniform if the characteristic impedance of feed network was the same and quantity of the antennas was increased constantly. This thesis purposed to design different characteristic impedance of feed network and compared with radiation gain and power distribution of feeding each antenna. This different Zo of feed network to divide into one section feed network and two sections feed network. Their characteristic impedance of feed network was 25ohm 40ohm and 70ohm in the one section feed network. There were two kind of Zo in the two section feed network. That was 25ohm and 40ohm. This thesis utilized the experiment to know that the radiation gain of the two section feed network was better then one section feed network.