The Choice of Subreflector Suprort Geometr for Earth Station Antennas

The sidelobe radiation associated with earth station antennas for satellite communication is rapidly becoming a critical design parameter. The efficiency of both frequency and orbit utilisation can be improved by control of the sidelobe response of the earth station antenna and, consequently, a reduction in the interference with neighbouring systems. It has been shown, (1,2), that this sidelobe response depends on several factors each requiring careful attention in the design phase. One of the least characterised of these factors is the scattering associated with the subreflector or feed support structure, particularly when this is of lattice construction. A measurement programme has been undertaken aimed at comparing the scattering associated with different types of support strut configurations which are commonly employed in large earth station antennas.