The extended aperture field integration method and its linearity in calculating the radiation pattern of reflector antennas

A symmetric paraboloidal reflector with a dipole feed is considered. An aperture plane is selected in front of the reflector and at different distances from its edge. The aperture field is calculated as a summation of the fields due to the direct, reflected and edge diffracted rays and the contribution of slope diffraction and caustic correction terms. In order to Increase the amount of the edge diffracted rays intercepted by the aperture, the aperture size is extended beyond the physical aperture of the reflector. The far-zone radiation pattern is obtained using Fourier transform of the total aperture field. The effects of the aperture location and aperture size on the radiation pattern are studied and presented. Also, the linearity of the extended aperture field integration method is investigated.