Numerical computation of radiation characteristics of rectangular waveguides

The E-field integral equation is used to determine the secondary fields from unknown induced currents on a rectangular waveguide's surface. To model the waveguide's surface, two hybrid orthogonal unit vectors are defined. Along one, surface currents are represented by discrete overlapping triangle basis functions and along the other by entire domain cylindrical basis functions. To enable the latter expansion, a parametric transformation is used to transfer the waveguide's cross-sectional contour onto a cylindrical one. The integral equation is then reduced to a matrix equation via the method of moments. The technique is then applied to numerically investigate the radiation characteristics of rectangular waveguides. The behavior of the solutions and the radiation patterns are studied to determine the mode convergence and the effect of various geometrical parameters.<>