12-element printed array antenna for INMARSAT-M maritime communications

In the maritime satellite communication system, the mechanism of 3 or 4-axis antenna mount is usually introduced rather than that of 2-axis antenna mount despite its simple mechanism. Because in the mechanism of the 2-axis antenna mount, as the antenna points toward high elevation angle, particularly in zenith direction, the tracking system become uncontrollable. The disadvantage is overcome by introducing electrical steering into the 2-axis antenna mount. From these points of view, the authors have developed an electrically steered high efficiency 12-element printed array antenna composed of a spiral antenna with a reflector