High-Gain Mobile Satellite Antennas

This paper outlines the state-of-art of High-Gain Mobile Satellite Antennas (MSA) and describes their designs, benefits and specific impacts in Mobile Satellite Communications (MSC). In many respects the MSA infrastructures currently available for MSC constitute the weakest links of the system. If the mobile antenna has a high gain, it has to track the satellite, following both mobiles and satellite orbital motions. Namely, sometimes this is difficult and expensive to synchronize. Therefore, if the vehicular antenna has low gain, it does not need to perform tracking but the capacity of the communications link is limited. In general, according to the transmission direction, there are three types of MSA: 1) transmitting and receiving or so-called transceiving, as a part of all types of Mobile Earth Station (MES); 2) only receiving is part of the special Inmarsat EGC receiver and 3) only transmitting is built in satellite beacon antennas for maritime, land and aeronautical applications. On the other hand, all MSA are classified into omnidirectional and directional tracking antennas. The Inmarsat, Eutelsat, ESA, Cospas-Sarsat, Iridium, Globalstar, ICO, Orbcomm, ACeS, Thuraya, Insat and other GEO and Non-GEO current and forthcoming mobile satellite operators have conducted research on all network segments, including different types of MSA and their future development and improvements. The Engineering Test Satellite-V (ETS/V) experiments conducted in Japan for the transmission of voice, video and different data rate digital communications between ships, land vehicles and aircraft were successful. Moreover, a test of low-speed data transmission by using briefcase-size transportable equipment, onto which two small printed antennas were mounted, was among the experiments.