Subspace methods and spatial diversity in radars

The utilization of diversity in radar systems has shown improvements over conventional beamforming phased array radars in many aspects of the system performance including target detection probability, the number of identifiable targets, and beam-pattern synthesis. When linearly independent signals are transmitted, the signals received from targets at different locations are also linearly independent. In using subspace methods such as MUSIC, this presents an advantage as spatial smoothing is no longer required. We present here a comparison of the performance of a MIMO radar system, with that of a phased array requiring spatial smoothing. The behaviour of the eigenvalues of the received data covariance matrix for radars with and without spatial diversity is presented, and the characteristics of the MUSIC spectrum of the two systems is compared.