Contents I. Introduction
The single-offset compact antenna test range (CATR) is a widely deployed technique for broadband characterization of electrically large antennas at reduced range lengths [1], [2]. The nature of the curvature and location of the offset parabolic reflector as well as the edge geometry ensures that the resulting collimated field is comprised locally of a pseudo plane-wave. The coupling of this plane-wave into the aperture of the test antenna creates the classical measured “far-field” radiation pattern. The accuracy of a pattern measured using a compact range is primarily determined by the uniformity of the phase and amplitude of the pseudo plane-wave illuminating the AUT aperture. The quality of the pseudo plane-wave is governed primarily by two factors: amplitude and phase taper (which is imposed by the radiation pattern of the feed and its location with respect to the reflector focus), and reflector edge diffraction (which usually manifests as a high spatial frequency ripple in the pseudo plane wave) [2]. Thus, CATR performance is generally specified in terms of the amplitude and phase ripple throughout a finite region of space, called the quiet-zone (QZ). As the configuration of the reflector edge treatment is so inextricably linked to the purity of the pseudo-plane wave, many different modelling techniques have been employed over the years to produce accurate simulations that can be used to optimize the design of the CATR.
