Scattering from 3-D cavities with a plug and play numerical scheme combining IE, PDE, and modal techniques

In this paper, we present a multidomain and multi-method coupling scheme called FACTOPO, based on generalized scattering matrix computations on three-dimensional (3-D) subdomains. The global target /spl Omega/ is split in N/sub V/ subdomains (V/sub i/)(i=1, N/sub V/), separated by N/sub I/ fictitious surfaces (/spl Gamma//sub j/)(j=1,N/sub I/). We use a modal representation of the tangent fields on the interfaces. In each domain, the generalized scattering matrix S/sub i/ is computed with different methods such as the 3-D finite-element method (FEM) or the electric field integral equation (EFIE). This coupling scheme leads to an important reduction in computational resources, especially for cavities with one dimension much larger than the other two. The advantages of this formulation for parametric studies is illustrated by two cases: computing the RCS of an air-intake terminated with a flat PEC or a fan (CHANNEL) and of an antenna structure coupled to an electronic feed with a varying parameter (DENEB). Numerical as well as experimental results are presented.