Aperture-Coupled Stripline-to-Waveguide Transitions for Spatial Power Combining

A full-wave electromagnetic model is developed and verified for a waveguide transition consisting of slotted rectangular waveguides coupled to a strip line. This waveguide-based structure represents a portion of the planar spatial power combining amplifier array. The electromagnetic simulator is developed to analyze the stripline-to-slot transitions operating in a waveguidebased environment in the X-band. The simulator is based on the method of moments (MoM) discretization of the coupled system of integral equations with the piecewise sinusodial testing and basis functions in the electric and magnetic surface current density expansions. Electric and magnetic dyadic Green’s functions used in this integral equation formulation are developed for an infinite rectangular waveguide in the form of partial expansion over the complete system of eigenfunctions of a transverse Laplacian operator. Numerical results are obtained and compared with a commercial microwave simulator for a few representative structures, including various configurations and planar arrays of slotted waveguide modules coupled to a strip line.