Inverse scattering from inhomogeneous disturbed region in planarly layered dispersive plasma medium

Abstract

In this paper, we applied the electromagnetic forward and inverse scattering algorithms to planarly layered dispersive plasma media. The media have four layers with different plasma frequency in each layer. The disturbed region is located in layer 2, and takes effect as an electromagnetic wave scatterer. We use the stabilized biconjugate gradient fast Fourier transform (BCGS-FFT) method to compute the forward scattering fields. By multifrequency calculation, we found that the scattered fields by the disturbed plasma region from using BCGS-FFT and those from full wave simulations using a commercial software showed good agreements. In inverse scattering procedures, Born iterative method (BIM) is used to reconstruct the relative permittivity values in the disturbed region, and thus the plasma frequency or electron density distribution in this region. As shown in Figure 1(a), the four layers are characterized by ∈ r1 = 1.0, σ 1 = 0, ∈ r2 = 2.0, σ 2 = 0.001 S/m, ∈ r3 = 3.0, σ 3 = 0.001 S/m, σ r4 = 4.0, σ 4 = 0.001 S/m and µr 1 = µ r2 = µ r3 = µ r4 = 1. The disturbed region (scatterer) is of the dimension 8×8×8 cm and ∈ r = 0.9, σ = 0.002 S/m. The radiation electric dipole is located at (0, 0, 10)m and the polarization is (1, 1,−1). The operating frequency is 1 GHz.