Transient Scattering by a Lossy Dielectric Cylinder: Marching-on-in-Frequency Approach

We consider the transient scattering of an electrically polarized, two-dimensional, pulsed wave by a two-dimensionally inhomogeneous, lossy dielectric cylinder embedded in free space. The problem is formulated in terms of a contrast-source domain integral equation over the interior of the cylinder. This integral equation is solved numerically, with the aid of the "marching-on-in-frequency" method recently proposed in [1]. To this end, a new discretization procedure is introduced, which is more accurate than the usual piecewise-constant moment-method approach. This discretization preserves the convolution-type structure of the continuous equation, which enables the repeated application of the "conjugate-gradient FFT" method. The initial estimates required in this method are generated by marching on in frequency, using a special extrapolation scheme. Numerical results are presented and compared with the results obtained by applying alternative techniques.