Highly Isolation Design of Microwave Landing Radar for “Tianwen-1” Mission
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Xi’an Institute of Space Radio Technology， Xi’an 710100， China
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摘要:
“天问一号”微波着陆雷达是探测器进入、下降与着陆（Entry，descent and landing，EDL）阶段的关键单机，采用了线性调频连续波（Linear frequency modulation continuous wave， LFMCW）体制，如何有效抑制LFMCW雷达接收回波中耦合的直波泄漏信号一直是提高雷达性能的关键问题。本文从雷达系统设计的角度出发，在满足系统轻小型化要求的前提下，提出了高隔离度天线设计、接收机中频输出信号滤波设计以及数字信号处理中泄露信号抑制相结合的方法，有效地解决了LFMCW雷达直波泄露的问题。通过分析外场直升机校飞试验实测数据，证明采用上述方法后，可大幅抑制直波泄露信号，并可将直波泄露信号携带的相位噪声抑制10~15 dB。
Abstract:
The microwave landing radar is a linear frequency modulation continuous wave （LFMCW） radar， which is a key instrument for “Tianwen-1” spacecraft during its entry，descent and landing （EDL） phase. Signal leakage has become the key factor that restricts the performance of LFMCW radar. In order to satisfy the requirement of small， light and high isolation radar system， this paper combines certain methods including a high isolation antenna design， intermediate frequency filtering and leakage suppression in digital signal processing. It is proved by a helicopter test that these methods can filter out the leakage and reduce the phase noise of leakage signal about 10—15 dB by analyzing data.