Research Of The Quit Zone Performance Of Compact Antenna Test Range With Phaseless Measurement

Compact Antenna Test Range(CATR)technology refers to the technology of measuring antenna parameters or radar target scattering characteristics in the far field at close range.It is an important topic in the field of antenna and target characteristic measurement and an effective method to solve the problem of high frequency antenna testing such as millimetre wave/submillimetre wave antennas.The antenna under test must be illuminated by pseudo-plane wave as the far field measurement.The spherical wave radiated from feed will be transformed to a plane wave of the quiet zone with the help of compact antenna test range system.Three key indicators for evaluating the performance of plane wave in the quiet zone are:amplitude deviation,phase deviation,polarization purity.The first two indicators indicate the difference between the pseudo-plane wave and the ideal plane wave.The last one indicates the polarization purity of the quite zone.The amplitude refers to the range of amplitude of the quiet zone.In the actual detection,the intersection of any vertical plane of the quiet zone and the horizontal or vertical planes are generally selected as the evaluation index of the variation amplitude.The phase deviation of the quiet zone is the same.In order to solve the problem of phase disturbance of the quiet zone by probe scanning in the case of high frequency,it is necessary to derive the phase distribution only by the intensity distribution of the electromagnetic field.The phase retrieval algorithms are commonly used in the field of image and optics including iterative algorithms,transport of intensity equation algorithm and phase space algorithm.This research focuses on applying the iterative algorithms and transport of intensity equation algorithm to the quiet zone performance evaluation of the compact antenna test range.The theory of the iterative algorithm is understandable It has the advantage of anti-noise and continuous error reduction,but it is sensitive to the selection of the initial value and easy to fall into the local minimum point.The transport of intensity equation algorithm is fast without iteration.However,the accuracy is relatively low due to the approximation during the calculation.Considering the advantages and disadvantages of two methods,this paper combines the two methods to predict the phase with amplitude data only.The result of the transport of intensity equation is substituted into the GS iteration method as the initial phase.The author applied the traditional G-S algorithm and the improved TIE-GS algorithm for the calculation of the phase of the quiet zone,and verified algorithms with GRASP8 simulation data and the measured data.