Online Transmit Beampattern Notching for Colocated MIMO radar

Radar system may receive deceptive targets from hostile active Electronic Counter Measurement (ECM) devices if its signal is detected by an ECM device. In practice, once the direction of the ECM device is located, it makes sense to form a notch at the transmit beampattern in the direction. Current transmit beampattern notching techniques for colocated Multiple-Input Multiple-Output (MIMO) radar mainly use waveform optimization methods, which however has a huge computation cost. In this paper, we propose an online MIMO transmit beampattern notching method that is formulated as a linear programming problem and then can support online implementation for its low computation cost. The basic concept is to slightly vibrate the phases of a group of MIMO waveforms optimized offline for certain purpose such that transmit beampattern notching would not spoil too much properties of original waveforms. Numerical results indicate that for an omnidirectional MIMO transmit beampattern formed with 4 transmit waveforms each with 128 codes, this method can form a -22dB transmit beampattern notch, whereas the peak sidelobe level grows merely 1.25dB.