Novel Antenna System Design for Satellite Mobile Multimedia Service

In this paper, the triband mobile antenna system for broadband multimedia service in the Ka/K band and direct-broadcast-satellite service in the Ku band is proposed. The proposed antenna has a modified hybrid antenna (HA) structure with a Cassegrain reflector system with feeder for the K/Ka band, and a microstrip array for Ku-band service is composed of four linear subarrays and stacked on the subreflector of the HA. The main purpose of the proposed HA is to realize a high-gain mobile satellite antenna system with rapid 2-D beam scanning ability at low cost. Therefore, we proposed a novel beam-steering method through a subreflector that is rotational and flat. The feeder is composed of 20 dual-band and dual polarized horn elements in a hexagonal structure with an oval-shaped rim to maximize the efficiency of the HA. For system size reduction, small-sized active channel blocks composed of four channels were developed for signal amplification and main beam control, and the active channels for the transmitter and the receiver are connected with the horn elements of the feeder, respectively. In addition, the triplexers were very helpful for structurally simplifying the HA. A fabricated HA was successfully tested in a Korean satellite communications environment with motion simulator that can replace motor vehicles, and all radiation patterns in a beam-steering angle meet the international regulation of the International Telecommunication Union Radiocommunication Sector S.465-5.