Fast and accurate calculation of sea echo Doppler spectrum in high frequency band

Since multilevel fast multipole algorithm (MLFMA) is the most effective method for the exact solution of scattering characteristics of electrically large objects, MLFMA is applied to two-dimensional sea surface scattering in high frequency (HF) band in this paper. Firstly, dynamic ocean surface modeling and incident wave form selecting are discussed, which should be considered especially for sea surface scattering using MLFMA. Then sea echo Doppler spectrum of HF radar is simulated. Results show that there are obvious first-order, second-order and third-order peak in the Doppler spectrum. And the positions of these peaks are consistent with the theoretical results based on Bragg scattering mechanism of sea surface in HF band. At the same time, the intensity difference between the first-order peak and the second-order peak is consistent with actual situation.