Analysis of 3D bodies with periodicity in one direction and finite sized in the others using a combined formulation in both real and spectral domains

A numerical scheme to analyze 3-D bodies of resonant size with arbitrary geometry and material composition is presented. The bodies are periodic in one direction (y): in the other directions (x,z) the bodies are finite sized. A new formulation has been developed and it is applied in combination with the conjugate gradient-fast Fourier transform method. The formulation is based on the discretization and the resolution of the EFIE (electric field integral equation) in both real and spectral domains, obtaining a very efficient and accurate numerical procedure. Some results on radar cross section, equivalent currents. and fields inside the body for a specific 3D periodic structure (infinitely long cylinders with arbitrary shape and material composition) are presented and successfully compared with analytical solutions.<>