Efficient Analysis of EM Scattering from Multiple Identical Targets Using a Tailored ACA-MoM

To solve the electromagnetic (EM) scattering from multiple identical rigid targets with traditional ACA-MoM, the multiple targets are treated as a whole, and the ACA is introduced directly without considering the characteristics of the target. This results in repeated storage of sub-matrices, low simulation efficiency, and large memory requirements. To overcome the disadvantages mentioned above, a tailored ACA-MoM is proposed and validated in this paper. In the new algorithm, only one target needs to be divided by octree, and the traditional ACA-MoM is applied to construct the self-interaction impedance submatrix of this target. Based on the translation rotation invariance of the Green's function, the self-interaction impedance submatrix of other targets is the same as that of the established one. Therefore, only one self-interaction impedance submatrix is established and stored in the new algorithm, which results in a large reduction in simulating time and memory requirements. And then the ACA is introduced again to establish the interaction impedance matrices between any two targets, in which translation and rotation are performed to obtain the triangular and RWG information of other targets, and a so-called adaptive near-field coupling (AD-NFC) technique is proposed and introduced. According to AD-NFC, the interaction impedance submatrix is compressed by ACA directly once the distance between the center of the targets is greater than twice the maximum length of the target. As a result, the simulating time is further reduced. Numerical results demonstrate the accuracy and efficiency of the new algorithm.