中国物理B ›› 2010, Vol. 19 ›› Issue (8): 84103-084103.doi: 10.1088/1674-1056/19/8/084103
张彦敏1, 王运华2, 赵朝方2
Zhang Yan-Min(张彦敏)a), Wang Yun-Hua(王运华)b)†, and Zhao Chao-Fang(赵朝方)b)
摘要: It is well known that the sea return echo contains contributions from at least two scattering mechanisms. In addition to the resonant Bragg scattering, the specular point scattering plays an important role as the incidence angle becomes smaller (≤20o). Here, in combination with the Kirchhoff integral equation of scattering field and the stationary phase approximation, analytical expressions for Doppler shift and spectral bandwidth of specular point scattering, which are insensitive to the polarization state, are derived theoretically. For comparison, the simulated results related to the two-scale method (TSM) and the method of moment (MOM) are also presented. It is found that the Doppler shift and the spectral bandwidth given by TSM are insufficient at small incidence angles. However, a comparison between the analytical results and the numerical simulations by MOM in the backscatter configuration shows that our proposed formulas are valid for the specular point scattering case. In this work, the dependences of the predicted results on incidence angle, radar frequency, and wind speed are also discussed. The obtained conclusions seem promising for a better understanding of the Doppler spectra of the specular point scattering fields from time-varying sea surfaces.
中图分类号: (Instruments and techniques for geophysical research: Exploration geophysics)