低軌衛星Ka頻段地面終端雙極化暨圓極化陣列天線系統

Abstract

本論文提出了兩組應用於Ka頻段低軌衛星系統的主動式天線陣列，其中一組為雙極化TX(27.5~30GHz)與RX(17.7~20.2GHz)64天線單元模組分別製作於8層與10層電路板上。TX系統使用16顆瑞薩(Renesas)公司製作的F6522波束成形晶片，RX晶片型號則是F6212。兩塊模組皆可簡單使用SPI通訊介面對板上所有晶片進行控制，系統內電源供應皆只需要外接3.3V輸入即可順利運作。天線設計部分採用鑽孔直接饋入的貼片天線且各單元之間的間距為該頻段最高頻率的0.45 波長。 另一套系統則是64TX與64RX共構的左圓極化天線陣列。使用孔徑耦合饋入貼片天線，單元之間採用交錯排列的方式可以有效降低模組所佔面積並增加系統的整合程度。但交錯排列的陣列結構會產生過低的交叉極化水平問題導致設計出的系統效能無法符合規格，為解決此問題本論文亦提出使用最佳化演算法進行波束成形，藉由犧牲些許的主極化增益換取較高的交叉極化水平。有鑑於在Ka頻段的低軌衛星通訊應用上往往會需要較大的天線增益以及輸出能量，這兩項要求皆可透過擴大天線陣列來達成。模組化的好處在於可以簡單藉由拼接複數小型陣列系統的方式等效成一高效能的大型陣列系統，且容易維修以及替換。這在各方面的應用上都預期能有出色的表現

This paper proposes two sets of active antenna arrays for Ka-band low Earth orbit satellite systems. One set consists of dual-polarized TX (27.5~30GHz) and RX (17.7~20.2GHz) 64 antenna element modules fabricated on 8-layer and 10-layer circuit boards, respectively. The TX system uses 16 Renesas F6522 beamforming chips, while the RX chip model is F6212. Both modules can easily control all the chips on the board using the SPI communication interface, and the system's power supply only needs an external 3.3V input to operate smoothly. The antenna design uses via-fed patch antennas, with a spacing between elements of 0.45 wavelengths at the highest frequency in each band. The other system is a 64TX and 64RX co-structured left circularly polarized antenna array. It uses aperture-coupled patch antennas, and the elements are arranged in an interleaved manner to effectively reduce the module's size and increase system integration. However, the interleaved array structure can lead to excessively low x-pol level, resulting in the system's performance not meeting specifications. To address this issue, this paper also proposes using optimization algorithms for beamforming, sacrificing some co-po gain for higher x-pol level. Given that Ka-band low Earth orbit satellite communication applications often require higher antenna gain and output power, these two requirements can be achieved by expanding the antenna array. The modular approach allows for the simple equivalent of a high-performance large array system by splicing multiple small array systems, making it easy to maintain and replace. This is expected to perform exceptionally well in various applications.