A multibeam Earth station antenna for accessing satellites with inclined orbits

A multibeam antenna is being investigated that allows an enhanced view of the geostationary arc and hence permits access to satellites with inclined orbits. The antenna uses two reflectors in an offset Cassegrain configuration. Multibeam operation is achieved over a region about the geostationary arc by shaping both reflectors. Tracking satellites with this antenna is achieved by moving the feed horns, as opposed to the conventional approach of moving the entire antenna. To test the electromagnetic design predictions, a prototype multibeam antenna to allow simultaneous access to AUSSAT and INTELSAT satellites at Ku-band is being constructed. This antenna covers a 20 degrees segment of the geostationary arc, and satellite inclinations up to +or-3 degrees . It has a main reflector diameter of 3.63 m and within this rectangular coverage region the average beam efficiency is about 70%. A significant factor in the approach is the method of manufacturing the shaped reflectors. Both the main and subreflector surfaces are made from shaped panels using a technique developed at CSIRO.<>