The Effect of Antenna Mutual Coupling on MIMO Radar System Performance

Multiple-input multiple-output (MIMO) radar systems use orthogonal signaling to enable combined transmit and receive beamforming through signal processing on the received signals. Because of the combined role of transmit and receive arrays in this processing for monostatic MIMO radar, mutual coupling present in these arrays impacts the beamforming in a unique way. This paper presents a mathematical model of a MIMO radar with coupled antennas and appropriate radio frequency circuitry. Application of the model to evaluate radar detection of a single target demonstrates that coupling can result in target detection angles that are in error by as much as 12 degrees and increase beamformer response sidelobe levels by as much as 8 dB. The results also show that a simple matching network can improve detection performance, particularly when array mutual coupling is high.