Interference Suppression Method With MR-FDA-MIMO Radar

In the conventional array radar, the suppressible interference is generally limited by the array element number, referred to as the degree of freedom (DOF) of the array. Similarly, the suppressible number of deceptive interference is limited by the transmit element number of frequency diverse array (FDA) multiple-input multiple-output (MIMO) radar. In this article, an interference suppression method based on data-independent beamforming is proposed with FDA-MIMO radar by using a minimum redundancy array (MRA) design in its transmit port, referred to as MR-FDA-MIMO radar. This break through the limitation on the number of suppressible deceptive interferences. The MRA is employed to obtain extended DOF by using difference coarray, resulting in the suppressible number of order O(2M) with M transmit element number. The beamforming method consists of two manifolds: 1) in the receive beamforming stage, the possible target is preserved by using orthogonal subspace projection and the sidelobe barrage interference is suppressed; and 2) in the equivalent transmit beamforming stage, possible nonideal factors are taken into consideration for constructing the covariance matrix to widen the notches corresponding to the predicted deceptive interference. The proposed method outperforms in terms of number of the suppressible deceptive interferences and the signal-to-interference-plus-noise ratio, which is demonstrated with simulation examples.