The radiation of symmetrical horn antennas with walls of infinite conductivity

The radiation characteristic of horn antennas can be calculated by the Kirchhoff-Huygens integration, if the field in the aperture is known. For a class of inhomogeneous waveguides, which cannot be treated by separating the wave equation, the field of the dominant mode has been calculated by the finite-difference method. By means of the results the various approximate field distributions used so far in the aperture of pyramidal horns have been examined. By comparing the calculated and experimental radiation patterns the effectiveness of the Kirchhoff-Huygens integration has been proved. Finally the developed numerical method has been applied to the problem of finding the aperture contour of a horn for circular polarization.