Design and verification of a shaped-beam reflector antenna for Malaysia beam coverage

Reflector antenna system has been widely used in many satellite applications to produce high gain signal for data transmission. However, some applications require the beam to be shaped according to the specific coverage region. For the beam shaping design, the beam width of the coverage area need to be calculated, and the feed position shall be adjusted to produce the desired beam. An exact design technique, called ray tracing method has been developed in this research to achieve the precise off-axis beams. Based on the ray tracing program, the correct feed position is determined based on the caustic generated by the traces and curves observed in the transmitting and receiving mode of the antenna system. Apart from determining the feed position, the program has been used to calculate the aperture phase distribution and the radiation pattern which will thus be used to verify and analyze the shaped beam. The results obtained from the MATLAB program are then verified through three-dimensional (3D) electromagnetic (EM) software.