Low Distortion And Multi-Channel Consistency Of Amplitude And Phase In Wideband RF System

The radio frequency simulation system is widely used in radar system performance testing and evaluation due to its comprehensive performance testing,good confidentiality and high economic efficiency.The research of multi-channel calibration of amplitude and phase consistency which can guarantee wideband RF simulation system performance has important practical value.Wideband LFM signals are widely used in high-resolution radars,especially SAR and ISAR,because of their good pulse compression characteristics.However,it will produce serious distortion of amplitude and phase after passing through the wideband RF system,which will affect the resolution and sidelobe performance of the radar.Therefore,the key problem of low distortion technology of amplitude and phase in wideband RF system needs to be solved urgently.This article studies and analyzes the key technologies in multi-channel calibration of amplitude and phase consistency in broadband RF simulation systems.An iterative algorithm for determining the control codes of attenuators and phase shifters based on attenuation values and phase shift values is studied.The software and automatic test of multi-channel calibration of amplitude and phase consistency is designed and realized.The test results show that after multi-channel calibration of amplitude and phase consistency,the amplitude deviation of each link of the RF simulation system is within ±0.25 dB,and the phase deviation is within ±3°,which meets the design specifications and system requirements.The characteristics of amplitude and phase of the wideband DRFM system are accurately estimated.And the characteristics of amplitude and phase of the DRFM system with different center frequencies and different bandwidths are obtained.This paper studies analog and digital equalization technology of amplitude and phase,designs and develops wideband amplitude equalizers and digital predistortion filters with 500 MHz bandwidth and 1000 MHz bandwidth and a filter with low group delay fluctuation with 500 MHz bandwidth,and puts forward low distortion technology of amplitude and phase integrating analog and digital equalization technology of amplitude and phase.Using wideband amplitude equalizers and digital predistortion filters,the analog and digital equalization technology of amplitude and phase and low distortion technology of amplitude and phase of the DRFM system are respectively verified experimentally.The experimental results show that after equalization of amplitude and phase,the amplitude fluctuation of the DRFM system is within 3dB,and the group delay is within 3ns,which achieves the expected target.