Hangkong bingqi (Feb 2024)
Analysis of Direction Finding Performance of Interferometer for Frequency Division Orthogonal MIMO Radar
Abstract
The spatially synthesized signal pulse of the frequency division orthogonal MIMO radar has the characteristics of time-varying envelope and space-time coupling, which provides a new possibility for actively countering direction finding of the passive electronic reconnaissance system. This paper is dedicated to analyze the direction finding error of the electronic reconnaissance system to the frequency division orthogonal MIMO radar by the phase interferometer direction finding system. Firstly, the MIMO radar synthetic signal model is established for the far-field reconnaissance receiver, and then the influence of the time-varying envelope and phase wavefront distortion characteristics on direction finding performance are analyzed. Moreover, a feasible method based on initial phase modulation is proposed to increase the interferometer’s direction finding error. Simulation results indicate that the dominant regions of DOA estimation errors in interferometers are different due to the influence of phase wavefront distortion and instantaneous signal-to-noise ratio. In addition, the envelope fluctuation characteristics can be manipulated by phase modulation of MIMO radar elements, and the peak to average ratio (PAR) of the synthesized signal can be changed to increase the anti interception performance. In the analysis window of the interferometer, compared with the synthesized signal of phased array radar, when the prior position of the reconnaissance receiver is accurately known, the power of the MIMO radar synthesized signal can be reduced by 25 dB and it can also be reduced by 10 dB when the distance is unknown. Therefore, MIMO radar can increase the direction finding error of the interferometer to a certain degree.
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