Microwave Imaging in Frequency Domain for Through-Wall Multiple Conductors

Abstract

Abstract This paper presents an inverse scattering problem for through-wall imaging. Two separate perfect-conducting cylinders of unknown shapes are behind a homogeneous building wall and illuminated by the transverse magnetic (TM) plane wave. After an integral formulation, a discretization using the method of moment (MoM) is applied. The through-wall imaging (TWI) problem is recast as a nonlinear optimization problem with an objective function defined by the norm of a difference between the measured and calculated scattered electric field. Thus, the shape of the metallic cylinder can be obtained by minimizing the objective function. The asynchronous particle swarm optimization (APSO) is employed to find out the global extreme solution of the object function. Numerical results demonstrate that even when the initial guesses are far away from the exact shapes, and the multiple scattered fields between two conductors are serious, good reconstruction still can be obtained. In addition, the effect of Gaussian noise on the reconstruction result is investigated and the numerical simulation shows that even though the signal-noise ratio (SNR) is 20 dB, we can still get good results of reconstructions.