Fast Analysis of Local Current Distribution for Electromagnetic Scattering Problems of Electrically Large Objects

Meng Kong,Xinyuan Cao,Mingsheng Chen,Xianliang Wu,Liang Zhang,Qi Qi

doi:10.1109/access.2020.3007958

Abstract

To improve computational efficiency of obtaining local induced current distribution under multiple incidents angles when electromagnetic scattering problems of electrically large objects are considered, a novel method is proposed to form small-scale impedance matrix and reduce number of repeated calculation for different incident angles, which is implemented by following three steps. Firstly, an undetermined matrix equation including multiple incident angles is constructed by interrelating part field nodes and all source nodes on object surface. Secondly, the undetermined matrix equation is transformed into a form that conforms to the compressive sensing (CS) framework, which is solved by reconstructed algorithm to obtain approximate induced currents of all source nodes under a wide incident angle range. Finally, exact wide-angle currents of a given node are obtained by calculating total magnetic field, and neighborhood wide-angle currents of the given node can be expanded by choosing appropriate technology in different boundary conditions. Numerical results of electrically large objects shown the efficiency of the proposed method.

Highlights

Local electromagnetic scattering of electrically large object play important roles in estimating strong scattering points of targets [1], analyzing partial geometry modification problems [2], [3], and arranging antennas in platforms etc
To the underdetermined equation (6), (( T)m×n 2n×n) can be used as measurement matrix, the known (S T)m×N can be recognized as measurements of the unknown sparse vectorn×N, and (α T)n×N can be obtained by solving L-norm optimization problem as (α T)n×N = arg min ||(αT)n×N ||L
Compared with the traditional discretized boundary equation (DBE) method, the proposed method has the advantage of lower complexity to solve the underdetermined equation under multi-angle incidence, including L-norm optimization problem is solved by OMP twice, whose computational complexity is O(p1MNm + p2mNn), where p1 and p2 denote iteration steps in two times OMP, respectively

Summary

INTRODUCTION

Local electromagnetic scattering of electrically large object play important roles in estimating strong scattering points of targets [1], analyzing partial geometry modification problems [2], [3], and arranging antennas in platforms etc. Method of moment(MOM) is common numerical algorithm in solving electromagnetic scattering problems, which can obtain high computational accuracy by constructing and solving full-rank matrix equations, the resulted computational complexity is huge especially for electrically large targets [4], [5]. A novel method based on CS is proposed to calculate local induced current distribution as electromagnetic scattering problems over a wide incident angle range are analyzed. It is worth noting that the proposed method can obtain independent current at any local interesting nodes by constructing smaller undetermined matrix equation, and reduce the number of calculations greatly at multiple incident angles. CONSTRUCTING AN UNDETERMINED MODEL UNDER MULTIPLE INCIDENT ANGLES For local electromagnetic scattering problems, combined field integral equation(CFIE) can be discretized as a undetermined equation as. VM1(θ1) VM2(θ2) · · · VMn(θn) M×n in which θ denote incident angle,n is the number of incident angles, in other words, θ is discretized into θ1, θ2, . . . , θn

SOLVING THE UNDETERMINED EQUATION

OBTAINING LOCAL EXACT SOLUTION

COMPUTATIONAL COMPLEXITY ANALYSIS

AND DISCUSSION

Findings

CONCLUSION