基于分层介质模型的HF雷达高度计火星回波仿真研究

Echo of HF-band Radar Altimeter from Mars Based on a Multi-layer Media Model

火星次表层中的水探测是当前深空探测领域中的热门问题之一.高频(HF)雷达高度计具有较强的穿透能力,且能同时实现距离和功率测量,是火星次表层探测的重要手段.介绍了高频雷达高度计系统的原理和设计,通过分析高度计电磁脉冲与多层光滑介质之间的相互作用,得出其回波功率随时间变化的模型,并考虑了表面粗糙度对表面回波功率的影响.选用典型的火星分层介质模型,对其介电常数特性和高度计回波波形进行了仿真.仿真结果表明,采用高频雷达高度计系统可实现对火星次表层介电特性垂直廓线的反演,对火星中水的识别具有重要作用.

The detection of water in Mars is currently one of the most striking issues in deep space detection.High Frequency(HF) radar altimeter has good penetrating ability and can measure the range and power simultaneously.In this paper,the principles and design of the altimeter system were presented,the interaction between the altimeter electromagnetic pulses and multi-layer smooth media was deduced,and the model of the echo power with respect to the time delay was extracted.Besides,the effects of Mars surface roughness were also considered.Finally,two typical Mars multi-layer models were adopted,and the dielectric constants and the altimeter echo waveforms were simulated.Results of the simulation show that the vertical dielectric constant profile of Mars subsurface could be retrieved by HF radar altimetry,and the water in Mars could be identified in certain cases.