Approximate pattern calculation of a leaky waveguide

A method is described for calculating the patterns of leaky waveguides radiated from the aperture in the metal wall of a waveguide with a rectangular cross section, the waveguide and the aperture being assumed of infinite length along the axis, the tangential components of the electric field on the aperture being assumed to have been prescribed. This method is accomplished by substituting a well approved elliptic cylinder for a boundary with a rectangular cross section. Measurements have been made for the leaky guide to verify the accuracy of this method.