Estimation of clutter degrees of freedom for airborne multiple-input multiple-output-phased array radar

This study focuses on estimation of clutter degrees of freedom (DOFs) for airborne multiple-input multiple-output (MIMO)-phased array radar. Firstly, two equivalent clutter models are presented, according to the transmitting subarray beampattern and synthetic-phased centre, and based on the basic steering vector. Secondly, a convenient estimating rule of clutter DOFs for airborne MIMO-phased array radar under arbitrary transmitting subarray structures is presented and proofed strictly. Finally, the simulated results indicate that airborne MIMO-phased array radar is effective both in spatial selectivity and clutter suppression, and the clutter DOFs under arbitrary transmitted subarray structures can be estimated by the proposed rule exactly. The proposed models and rule are suitable for both conventional-phased array radar and airborne MIMO radar with uniform or non-uniform transmitting subarray and sparse array, and they are valuable for the improvement of space-time adaptive processing algorithm performance.