Calculation of the cross-polarization in the far field of waveguide radiators

Starting with the Kirchhoff-Huygens principle integral equations are developed for the problem of electromagnetic coupling of two domains through an aperture, e.g. between an open waveguide and the external region. The exact solution of the integral equations by the method of moments leads to the aperture field, the knowledge of which allows to calculate also details of the radiation pattern, as the crosspolarization, with great accuracy. Results are given for the radiation fields of circular waveguide radiators (1) within a perfectly conducting plane, (2) of finite wall thickness and (3) with a corrugated flange.