中文摘要：

侧重散射机理研究，以GPS相关函数和相关功率模型为基础，主要通过对双站雷达散射截面计算模型进行修改，得到裸土的GPS散射信号模型。其中裸土的双站圆极化雷达散射截面采用双站随机粗糙面散射模型计算得到，利用极化合成的方法使模型具备全极化计算功能。通过修改后的模型，模拟分析不同极化下裸土参数（土壤水分和地表粗糙度）对延迟多普勒图DDM（delay Dopplermap）的影响。该理论模型研究有助于机载／星载GNSS-R接收机数据解释、GNSS-R实验设计以及后向反演算法的开发。同时，延迟多普勒图模型的研究结果也为GNSS＋R土壤水分遥感研究提供了一定的理论依据。

英文摘要：

This paper focuses on the study of scattering properties. Based on the ocean GPS scattering model, a bare soil GPS scattering model is established. Considering the bistatic radar cross section, a random roughness scattering model is employed. After the modification, the effects of soil parameters （soil moisture and surface roughness） on delay Doppler map at different polarizations are simulated. This theoretical study is helpful for the interpretation of data from airborne/spaceborne GNSS-R receivers, experimental design and the inversion algorithm development. At the same time, the results of the delay Doppler map model can also provide a theoretical basis for the study of GNSS＋R soil moisture remote sensing.