Error Analysis Of Large-Aperture Compact Field Antenna Measurement System For Millimeter And Sub-Millimeter Waves

Compact Antenna Test Range(CATR)technology can solve the shortcomings of traditional antenna measurement technology in the measurement of high-frequency antennas for millimeter and sub-millimeter waves.CATR is essentially a pseudo-plane wave generation technology in a limited space.With the development of terahertz technology,the electromagnetic characteristics of high-frequency electrical large-size antennas have forced the CATR to develop in the direction of high frequency and large aperture.Large-aperture CATR generally makes and places the main panel by cutting into several small panels.A certain size of the gap between the panels will bring the diffraction,and then worsen the performance of the quiet zone.The CATR targeted in this paper is a large-aperture tri-reflectors CATR.The size of the main reflector reaches 3m × 3m and the main reflector is constructed by panel splicing.How to reasonably classify the errors existing in the processing,construction,and calibration of the CATR,model the CATR and give some theoretical guidance will become an urgent problem.In this paper,the errors of the CATR system are divided into three parts,which are the position errors of the component,the stitching errors and parameter errors of the main reflector,the gravity errors and temperature errors of the main reflector.The electromagnetic simulation of the CATR system is based on physical optics and physical diffraction theory.Because of the large simulation data,the characteristics of the quiet zone on the critical cut are statistically calculated and used as the basis for analysis.After a lot of simulation work,the limit values of various position errors are finally determined to guide the assembly and calibration work.The position control needs to ensure the angular rotation accuracy in first and keep the system symmetry of the main parabolic reflector.During the analysis of the stitching error and surface parameters error of the main parabolic reflector,the final stitching scheme and the specific number of sub-panels and the gap influence between the panels are determined.At the same time,the machining accuracy of the main reflector is limited to ensure better characteristics.The finite element analysis method is used in the gravity and temperature error analysis of the main parabolic reflector.The results show that the influence of gravity in the main reflector can be ignored without considering the deformation of the antenna backrest.The deformation of the back frame results in large phase ripple of QZ,it is necessary to optimize the scheme of the back frame and offset the gravity deformation during installation.The final temperature-change value of the microwave chamber with or without the influence of the antenna backrest is always±1℃,the base temperature of the microwave chamber is initially set at 20℃.