Analysis of nonrectangular cavity-backed patch antennas using edge-based hybrid finite element method with BiCG-FFT solver

To enable the use of the FFT (fast Fourier transform) in connection with the tetrahedral edge-based finite element-boundary integral formulation the authors propose a new approach for combining finite element and boundary integral matrices. This approach makes use of the space transformation concept to map the irregular gridding onto a fictitious regular one. Since the transformation matrix is highly sparse and may be obtained in the preprocessing phase, no additional memory is required aside from that needed for the implementation of the FFT.<>