On electromagnetic-wave radiation from the open end of a rectangular waveguide

The method of Vinichenko (1980) is used to analyze the problem of electromagnetic-wave radiation from the open end of a rectangular waveguide. It is shown that the results of the numerical calculation of the radiation pattern and results in the Kirchhoff approximation practicaly coincide for a rectangular waveguide with an ideally conducting flange. In the case of a waveguide with a black flange, the deviation between numerically obtained values and values obtained in the Kirchhoff approximation does not exceed 10 percent at radiation angles not greater than 70 deg.