立方衛星星際通訊S頻段陣列天線系統

Abstract

為因應 Lilium-2 與 Lilium-3 立方衛星（CubeSat）在低軌道（LEO）星際通訊與遙測任務中的需求，本論文提出一套適用於 S 波段（2.08–2.15 GHz）的主動式雙線極化陣列天線系統，以支援星對星（ISL）與星對地通訊並建立穩定鏈路。系統採用時分雙工（TDD）模式，透過數位控制精準切換收發時序，即使在高動態姿態環境下仍能維持可靠傳輸。

天線系統採 Tx/Rx 共構設計，單元間距為頻段最高頻率的半波長，並使用鑽孔直接嵌入式貼片天線降低結構厚度。每單元整合功率放大器（PA）與低雜訊放大器（LNA），搭配威爾金森功率分配器（等功率與不等功率配置）優化功率分佈，並以數位訊號開關控制射頻前端電源以降低待機功耗。

量測結果顯示，本系統在工作頻段內具備高穩定性、低交叉極化與良好方向容忍度，滿足小型化、低功耗及高可靠性需求，為新一代立方衛星 S 波段通訊酬載提供可行且高效的工程解決方案。

To meet the demands of the Lilium-2 and Lilium-3 CubeSats in low Earth orbit (LEO) for inter-satellite links (ISL) and telemetry missions, this paper presents an active dual-linear-polarized array antenna system operating in the S-band (2.08–2.15 GHz) to support both ISL and satellite-to-ground communications, enabling a stable link. The system adopts a time-division duplexing (TDD) mode with digitally controlled, precise switching between transmit and receive timing, ensuring reliable transmission even under high-dynamic attitude conditions.

The antenna system features a co-located Tx/Rx design, with element spacing equal to half the wavelength at the highest frequency in the band, and utilizes via-fed embedded patch antennas to reduce structural thickness. Each element integrates a power amplifier (PA) and a low-noise amplifier (LNA), combined with Wilkinson power dividers (configured for equal or unequal power) to optimize power distribution. Digital RF switches are used to control the RF front-end power supply, reducing standby power consumption.

Measurement results demonstrate that the system achieves high stability, low cross-polarization, and good directional tolerance across the operating band, fulfilling the requirements for miniaturization, low power consumption, and high reliability. This provides a feasible and efficient engineering solution for next-generation CubeSat S-band communication payloads.