A millimeter-wave compact range using an axially-symmetric paraboloid in a Gregorian configuration

Some of the design aspects of a practical millimeter-wave compact range employing an axially symmetric main-reflector illuminated by a shaped subreflector are presented. Although in principle any reasonable surface shape can be used for the main reflector (all that is required is that it provides a reasonably small caustic region when illuminated by an incoming plane wave), a paraboloid of revolution is used here. This choice is partially motivated by the fact that axially symmetric paraboloids are readily available on the antenna market, and hence provide a cost-effective alternative. Once the subreflector surface has been determined, the geometrical optics field produced at an arbitrary aperture location by a given feed element can be calculated using ray optics. The final co- and cross-polarized levels of the aperture field of the compact range are shown. This system covers a frequency range from 18 to 170 GHz and boasts a measured quiet-zone region with dimensions exceeding half the main reflector diameter.<>