A CG-FFT Scheme to Analyze Conducting Patches of Arbitrary Geometry in Multilayer Media

A Conjugate Gradient-Fast Fourier Transform (CG-FFT) scheme to analyze finite or periodic flat metallic patches over any arbitrary multilayer dielectric structure is presented. Arbitrarily shaped patches can be treated by using "rooftop" and "razor-blade" functions as basis and testing functions. Nearly all the computations are made in the Spectral Domain where analytical expressions for the Green\´s function can be found. A discrete Green\´s function periodic in both domains (real and spectral) is obtained. In the real domain the aliasing problems are avoided using a window function to limit the Green\´s function in that domain. These aliasing problems do not appear in the case of periodic structures where the formulation considered is mathematically exact. Several results are given and successfully compared with measurements or other numerical methods for both (finite and periodic) structures. In all cases the CG-FFT scheme appears to be very accurate and efficient.