First-order solutions for mutual coupling between waveguides which propagate two orthogonal modes

This paper describes a theoretical and experimental study of closely spaced open-ended waveguides radiating through a conducting ground plane. The waveguides are large enough in some cases to allew two orthogonally polarized propagating modes in each waveguide. A first-order analysis is presented which is based upon the method of moments and uses a single-mode approximation to the aperture field for each polarization. An improved first-order analysis is also presented which uses a higher order mode solution for the self-admittances. Close agreement with experiment is demonstrated.