Study of efficiency of spherical Gregorian reflector

The use of the current distribution method to analyse the field in the image space of a spherical Gregorian antenna when the main dish is illuminated by a linearly polarized plane wave is discussed. It is shown that the incident field distribution at the subdish is rather irregular, although it can be approximated by a smooth Gaussian distribution curve. In addition, it is possible to design a simple corrugated circular horn, so that the field at its aperture closely matches the incident field. As a result, a high efficiency wide-band system can be achieved.