A Novel 3-D Hybrid Approach for Simulating Electromagnetic Scattering From Electrically Large Targets in Ducting Maritime Environments

In this letter, we propose a novel 3-D hybrid approach for predicting the electromagnetic (EM) scattering from electrically large targets within ducting maritime environments. The approach integrates the 3-D parabolic equation (PE) method with the multilevel fast multipole algorithm (MLFMA), addressing separately the propagation of EM waves and the scattering by the targets. In addition, a data transfer scheme based on the discrete Fourier transform form of the 3-D PE is proposed to achieve a nearly lossless transition from the 3-D PE to the MLFMA. This scheme not only eliminates the need for local refinement of the PE grid but also avoids the interpolation approximation errors common in traditional interpolation-based hybrid schemes. Finally, a calm sea environment case is provided to validate the accuracy and effectiveness of the proposed method. Meanwhile, the EM scattering from a missile target under several representative cases within a surface ducting maritime environment is calculated and discussed.