Tradeoff study on array-fed reflector antennas for 100-beam-class multibeam communications satellite

Mobile satellite communications systems using 100-beam-class multibeam on-board antenna have been proposed and some of them are already in operation. Such systems can concentrate the resource, such as bandwidth, power, etc, on a specific beam. Therefore, these are effective for emergency operation under natural disaster. For such kind of the on-board antennas, size and power consumption are important to install the antenna in the satellite. We studied a tradeoff on the on-board antenna from the view point of size and power consumption. For that purpose, the size is evaluated by the element number of the feed-array The power consumption is evaluated by that of High Power Amplifiers (HPAs) connected with the elements, because the power consumption of HPAs dominates that of the satellite payload. On our study, we assume S-band system using cellular-phone-size terminals and 30 m-diameter on-board antenna which is an array-fed offset paraboloidal reflector antenna.