Efficient approach to analyze the dual-reflector antenna system with defocused feeds

A time-saving reflection point locating technique based on the geometrical optics approximation is proposed. The technique provides an efficient evaluation of a Cassegrain or Gregorian antenna system. For comparison, all the reflection points are calculated with the proposed technique and W.V. Rusch´s approach (1979). Patterns calculated by these two techniques show very similar results. However, the computation time of the proposed technique is only one-fourteenth that of Rusch´s approach. It is concluded that, for a slightly defocused feed system, the proposed approximation technique works well for a dual reflector antenna system. It can be extended to a monopulse tracking antenna system with multiple feeds.<>