Design of shaped-beam parabolic reflector antenna for Peninsular Malaysia beam coverage and its overlapping feed issues

Abstract

Design and performance of a shaped beam 12.2 GHz array-fed reflector antenna for broadcasting satellite is presented in this paper. Initial design, employing a cluster of feed horns illuminating a parabolic reflector is initially proposed for multi beam antenna (MBA) system to produce a contoured beam for Peninsular Malaysia. The precise feed positions are determined through a newly developed ray tracing program. Due to the small size of the coverage area, an issue with regards to physical constructability of the feed horns is raised. The MBA is modified by utilizing 18-element microstrip array as the feed, where each element positions are calculated by using the same caustic model. In this case, the preceding issue is solved, and high gain shaped beam coverage with uniform aperture is generated. This paper shows the results of the contoured beam antenna that have been achieved for beam scanned over a coverage size of approximately 0.9° long and 0.5° wide. Small variation of radiation level, which is less than 3dB within the edge of coverage (EOC), is also demonstrated in the performance analysis.