具動態波束配置性之天線系統設計

Abstract

在這篇論文中，我們提出一種可動態輻射不同增益場型的天線系統。此天線系統包含一使用印刷電路板以共振腔原理來運作的一分四功率分配器。由於共振腔內電磁場分布對稱的關係，此功率分配器可以在2.3 GHz到2.5GHz的所設計頻率範圍得到功率分配平均以及輸出訊號同向位的特性，進而獲得較高的隔離度。功率分配器的四埠再分別接入號角天線的輸入埠做訊號激發。特別的是，這四個號角天線是由雙平行金屬板在末端藉由四喇叭型開口所形成的四埠號角天線。在平行金屬板間放入金屬銅柱做為金屬隔離牆以增加四個號角天線間的隔離度。然而，最重要的是使由高頻切換器來做連接，當切換器開的時候訊號才餽入號角天線內；關的時候把訊號餽入到高頻阻抗內避免影響系統匹配。如此一來，我們可以不斷的四扇形區域內做波束切換。特別的是，我們提供多種不同的波束以涵蓋多樣化的區域。除了數值的模擬與分析外，我們還實際製作出成品並且量測其輻射特性。而實作結果的量測與模擬結果十分的吻合。

In this thesis, we reported a reconfigure antenna that is able to radiate different topologies of radiation pattern. Such an antenna system is composed of a 4-way power divider made from a cavity-type structure fabricated using printed circuit technology. Due to the symmetric electric field distribution in the resonant cavity, the power divider maintains equal amplitude- and phase- distribution in the frequency range from 2.3 GHz to 2.5 GHz. Moreover, the high isolation among the ports was obtained. The output ports of the 4-way power splitter are respectively connected to four E-plane horn antennas. Notably, the four E-plane horns are integrated in a metallic parallel-plate structure equipped with four flared open ends. To enhance the isolation among the four E-plane horns, the metallic cylinders array was employed as a sidewall of the horn antenna. Moreover, prior to connecting to each of the horn antenna the signal was connected to a Radio Frequency switch to turn on (to the antenna) or off (to a terminator). Therefore, we can dynamically switch the beam among the four sectors. Specifically, the beam pattern covering several sectors can also be obtained. In addition to the numerical simulation of the overall antenna structure, we have fabricated this antenna and measured its radiation characteristics. The excellent agreement between the measured and simulated results was obtained.