Sensitivity performance of several mappings in shaped offset Gregorian reflectors

The sensitivity performance of several primary pattern to aperture field mappings in shaped offset Gregorian reflector systems is investigated. Specific attention is given to high efficiency mappings with low second side-lobe levels, as these are of interest in the design of sensitive radio telescopes where the first side-lobe is imaged in the point spread function. Comparisons are made between the predicted analytical illumination efficiencies and the side-lobe levels, as well as the physical optics simulated sensitivity of the systems. The results show that the analytical trends are closely followed in actual shaped systems of moderate electrical size. Some graphs are given showing areas of maximum sensitivity for a specified side-lobe level in the shaping parameter space.