Fast Solution of Multiple Slot-Coupled Waveguide Junctions Using the CBFM

A method for the fast analysis of a large number ofwaveguides coupled through rectangular apertures of arbitrary size and placement is presented. To enable the analysis of weakly excited slots, an accurate method-of-moments approach employing basis functions corresponding to a modal expansion of the electric field in the slot cavities is utilized, which includes both polarizations of the electric field at the slot apertures, as well as the transverse variation of the field across the slot. The characteristic basis function method (CBFM) reduces the memory requirements significantly and speeds up the computation, and is used to analyze a junction with two branch waveguides with very weakly excited slots, showing excellent agreement with the commercial FEKO software. The runtime of the program is considerably faster than FEKO for these geometries