Method of moments analysis of displaced-axis dual reflector antennas

Abstract

Small symmetric dual reflector antennas suffer from low efficiency due to subreflector blockage of the main reflector and subreflector scattering. These can be reduced by slicing the main dish and translating its rotational axis, along with modifying the subreflector geometry. This type of design is usually applied to low-frequency reflectors, but high-frequency analysis techniques are used. Consequently the agreement between measured and computed data is not as good as it would be for a rigorous solution such as the method of moments. This thesis modifies an existing method of moments computer code to handle the displaced axis geometry, and computes the radiation pattern and the efficiency of this antenna as a function of geometrical and electrical design parameters. Optimum configurations are identified for several feed types.