Doppler Simulation and Analysis for 2-D Sea Surfaces Up to Ku-Band

The numerical simulation of Doppler spectrum for 2-D sea surfaces at high microwave bands requires a huge number of sample points for the sea surface, which leads to a huge amount of computation and requires a large computer memory. As a result, the Doppler simulation for 2-D sea surfaces at high microwave bands is considered to be a great challenge. In this paper, the Fourier spectrum of 2-D sea surface is decomposed into multiple blocks, and the sea surface corresponding to the complete Fourier spectrum is generated block by block. Then, the weighted curvature approximation method is adopted and the electromagnetic (EM) scattering fields of the 2-D time-evolving sea surfaces are obtained after calculating the scattering contributions of the blocks separately. In this way, the Doppler spectra of 2-D sea surfaces up to the X-band and Ku-band are simulated. To illustrate the behavior of Doppler spectrum for 2-D sea surfaces, Doppler spectra for 2-D linear and choppy wave model sea surfaces are simulated and analyzed under different radar and environment parameters. Conclusion for the evolution of Doppler spectra with incident angle, wind direction, and radar frequency is obtained. Moreover, the numerically simulated Doppler characteristics are compared with the results of analytical prediction and the results for 1-D sea surfaces. Although similar behaviors are observed in the comparisons, the details are different.