Title :
Investigation of crosspolarisation in offset Cassegrain antennas
Author_Institution :
James Cook University of North Queensland, Department of Electrical & Electronic Engineering, Townsville, Australia
Abstract :
The geometric optics condition for zero crosspolarisation in offset Cassegrain antennas is discussed. It is shown that with a feed having perfect pattern symmetry the crosspolar performance of the offset Cassegrain is limited by diffraction. As a result minimum crosspolarisation is only achieved at the geometric optics condition when the subreflector diameter is at least 40 wavelengths.
Keywords :
reflector antennas; geometric optics; offset Cassegrain antennas; subreflector diameter; zero crosspolarisation;
Journal_Title :
Electronics Letters
DOI :
10.1049/el:19810412
