A Study of Shift-frequency Jamming Based on Active Radar Transponder

In this paper, an implementation method of shift-frequency jamming against synthetic aperture radar based on active radar transponder is proposed and the basic principle of center frequency shift of echo signal using active radar transponder is deduced firstly. Then, the theoretical model of shift-frequency jamming imaging is analyzed and the main influencing factors of shift-frequency jamming imaging characteristics are discussed based on the model. Meanwhile, the imaging results of jamming signals under different frequency shifts are simulated and analyzed combined with three imaging quality indexes of the peak sidelobe ratio, the integrated sidelobe ratio and the impulse response width. The analysis results show that shift-frequency modulation leads to the frequency modulation rate mismatch of azimuth matched filtering, the range cell migration correction error and the loss of range bandwidth, which will further cause the gradual broadening of the imaging result of shift-frequency jamming signal along the azimuth direction and finally from the point target to the azimuth strip target. The jamming imaging simulation experiments are performed with the original echo data and the obtained results verify the validity of theoretical model and provide a basis for the implementation and application of shift-frequency jamming based on active radar transponder.