Parametric characterization of parabolic reflector antennas fed by focal plane arrays

The study has resulted in the following conclusions. The initial benefit of including Airy sidelobes in the FPA sampling is large, i.e. the efficiency climbs steadily as the number of sidelobes increases from zero. Hence it is inadequate to just sample the main lobe or even up to only one sidelobe. For optimal performance, it is seen from Fig. 2 that around 2 to 3 sidelobes are needed - often closer to three. The Airy excitation gives lower efficiency for deeper reflectors, as it represents the theoretically correct efficiency only for the shallow case. Therefore, there is a need for studying alternative excitation functions, or optimizing it. The coupling efficiency decreases strongly when the element spacing is smaller than 0.2 wavelengths. Therefore, very small element spacings should be avoided.