FFT-accelerated analysis of scattering in rectangular cavities loaded with lossy dielectrics

An efficient integral-equation method is presented for analyzing scattering from arbitrarily shaped three-dimensional (3-D) lossy dielectrics in a rectangular cavity. In the proposed adaptive integral method, the computationally dominant propagation step is accelerated by decomposing the rectangular-cavity Green functions into eight components that are in convolution or correlation form in the three Cartesian directions. This results in eight types of nested block-Toeplitz or block-Hankel propagation matrices that are multiplied using 3-D FFTs.