Numerical results for diffraction by a parallel-plate waveguide

In designing waveguide phased arrays, it is often found useful to have the knowledge of the diffraction pattern and excitation coefficients of a semi-infinite parallel-plate waveguide illuminated by a plane wave. To the best of these authors´ knowledge, numerical results for the above quantities have not appeared elsewhere in the literature. It is the purpose of this note to present some calculated results for the above quantities, with the guide dimension and the incident angle of the plane wave as parameters.