Subreflector and feed scattering in dual-shaped reflector single chamber compact ranges

The authors consider three analytic feed horns of the cos/sup N/ (/spl theta/) type where N is chosen in such a way as to achieve a specified subreflector edge taper at the edge half cone angle /spl theta//sub M/. Edge tapers of -30 dB, -20 dB, and -10 dB are chosen. Three different reflector profiles are then synthesized with the same geometrical-optics aperture distribution and diffraction-analyzed at various positions in the measurement zone of the compact range. Field computational results are compared with and without the feed and subreflector fields added into the computations at the observation points in the measurement zone. It has been demonstrated that, in dual-shaped reflector single chamber compact range systems, the edge taper on the subreflector can be reduced - without affecting performance - such that subreflector diffraction scattered fields contribute very little to the measurement zone ripple.<>