1998 年 46 巻 528 号 p. 63-70
Recently, focus has been placed on the development of mobile communications and broadcasting systems using GEO satellites. To realize these systems, a development of a beam synthesis technology for the satellite antennas is a matter of great importance, so that several design methods such as antenna gain optimization have been reported. However, no design considering the radiation characteristics of the mobile antenna has been reported. This paper describes a beam synthesis method which can compensate for the radiation characteristics in the elevation angles of the mobile antenna. The shaped beam by using this method makes it possible to provide uniform service quality throughout coverage area of the systems, because the beam shape on the satellite and mobile antenna are just the opposite. We will first present this method, and its shaped beams with an offset parabolic antenna which uses a 13-element feed. These shaped beams designed for a switching planer array antenna composed of 12 circular microstrip antenna elements which are arranged to form a cross so that we could obtain a simple tracking mechanism. We will then present a new feed system using a Hybrid Matrix Amplifier.