X頻段圓極化可控波束天線

Abstract

本論文中設計一個應用於衛星通訊元件之圓極化可控波束天線，操作頻率為8.2GHz，主要架構包含了圓極化天線陣列、相移器、功率分配器以及放大器等元組件。天線波束是否能準確指向衛星達到通訊之目的，皆取決於這些元組件的有效設計，有鑒於此，本論文擬針對X頻段圓極化可控波束天線進行研究，了解相關元組件的功能、原理、運用與其設計方式，規劃整體系統設計圖與實體組成圖，並進行實作與量測以達到要求之規格。設計此天線陣列最重要的考量因素是需要好的圓極化性、波束的集中度以及較大的旁波束差值，如此一來進行掃描的時候，偵測準確度也會較大，若旁波束過大，如果掃描端經由旁波束偵測，易造成誤判。因此根據天線陣列理論，適當的設計能量之分布以能降低旁波束之大小。

In this thesis, circular polarized array antenna with steerable main beeam applied to X-band satellite communications system has been designed, and the operating frequency is 8.2GHz. The structure includes a circularly polarized antenna array, phase shifter, power divider, amplifier and the other components. Whether the antenna main beam can accurately point to the purpose of the communication satellite, the design of these elements are dependent on the effective components. In view of this, this thesis intends to reasearch X-band circularly polarized antenna with steerable beam. To understand the functions, principles, and ways to design of components, planning overall system design and entities, manufacturing and measuring in order to achieve the requirements of the specifications. This design of the antenna array of the most important considerations is the need of a good polarization and beamforming antenna array, big sidelobe level, therefore the accuracy of detection will be larger. If the sidelobe is too large, when the scanning edge detected by sidelobe, could easily lead to measure error. Therefore, according to the antenna array theory, the appropriate power distribution was designed to be able to reduce the sidelobe.