High frequency asymptotic analysis of modal excitation at flanged parallel plane waveguides

Ray analysis has been executed for obtaining modal excitation coefficients at the flanged parallel plane waveguides. Previously derived formula has been extended to include multiple edge diffraction contributions between the aperture edges. By comparing the results by other methods, it has been shown that the contribution due to the doubly edge diffracted rays can improve the excitation coefficients for the transitional waveguide mode.