Hybrid method of FG-FFT and PO for radiation calculation from antennas around an electrically large conducting platform

An efficient hybrid scheme combining fitting Green's function (FG) fast Fourier transform (FFT) and physical optics (PO) is presented to investigate radiation from antennas around an electrically large conducting platform. The whole region is divided into full wave region and PO one. Similar to hybrid method of integral equation FFT (IE-FFT) and PO, this hybrid method features acceleration by FFT, fewer unknowns, less computing time than traditional IE-FFT. Differently, realization of FG-FFT is established by fitting the Green's function onto the nodes of a uniform Cartesian grid, not by Lagrange interpolation. Several examples are given to prove the hybrid method of FG-FFT and PO in this letter featuring higher accuracy and being not sensitive to both grid spacing and the expansion order compared to hybrid method of IE-FFT and PO.