A Multipurpose and Efficient Evaluation Method of Phase Characteristics in a Quiet Zone for a Defocused Feed in a Compact Antenna Test Range

A compact antenna test range (CATR) is an important testing facility for assessing electromagnetic characteristics of various wireless devices, in which the degradation of phase performance in a quiet zone due to feed defocusing severely affects the assessment results, especially for a higher frequency and longer defocusing distance. Based on the theory of geometric optics (GO), this paper precisely derives analytical formulas of phase characteristics in a quiet zone for a defocused feed in a commonly used CATR, such as that underpinned by single paraboloid and dual parabolic cylinders. The proposed evaluation method is of high accuracy and efficiency for higher frequencies and can be used in various scenarios with excellent results. The discrepancy between the formula calculation results and software simulation results of the machining accuracy tolerance for feeds and their turntable remains below 1°, demonstrating much better performance than the state of the art. Meanwhile, the deviation of the formula calculation results from the preset position of the feed stays within 1 mm, effectively supporting the confirmation of the feed position for equivalent pitch tests.