Coherent Jamming Technique Countering ISAR

For the reduction of sampling bandwidth,Inverse synthetic aperture radar(ISAR) echoes are usually dechirped first in the receiver.Then the dechirped signal employs FFT to get the range image in frequency domain.In general,the bandwidth of the target image is much less than that of the radar signals.So the narrowband signal can be used to modulate the receiving signal.Coherent jamming is proposed for jamming ISAR.Some video signals modulate the receiving signal in frequency domain,then the resulting signal is retransmitted.The dechirped output of the coherent jamming will produce cover jamming.Thus,ISAR can not obtain the range image.The paper also studies the effect of phase modulated jamming on the Doppler image.The coherent jamming can obtain some processing gain,so it can save jamming power.Theoretical analysis and computer simulation justify the validity and efficiency of this jamming technique.