Time domain microwave imaging for a metallic cylinder by using evolutionary algorithms

Abstract

This paper presents the studies of time domain inverse scattering for a metallic cylinder based on the finite difference time domain (FDTD) method and the evolutionary algorithms (EAs). For the forward scattering, the FDTD method is employed to calculate the scattered E fields. Base on the scattering fields, these inverse scattering problems are transformed into optimisation problem. The idea is to perform the image reconstruction by utilisation of some optimisation schemes to minimise the discrepancy between the measured and calculated scattered field data. They are the asynchronous particle swarm optimisation (APSO), dynamic differential evolution (DDE) and the non-uniform steady state genetic algorithm (NU-SSGA). The suitability and efficiency of applying the above methods for microwave imaging of a two-dimensional metallic cylinder are examined. Numerical results show that good reconstruction can be obtained by all optimisation methods. However, the DDE outperform the NU-SSGA and APSO regarding the reconstruction accuracy and the convergent speed in terms of the number of the objective function calls. In addition, the effects of Gaussian noise on the reconstruction results are investigated.

Keywords:

• time domain inverse scattering
• finite difference time domain (FDTD)
• subgridding FDTD
• asynchronous particle swarm optimisation (APSO)
• dynamic differential evolution (DDE)
• non-uniform steady state genetic algorithm (NU-SSGA)