Element Space DOA Estimation for Directional Transmission Scanning Phased Array Radars

Apart from MIMO, high resolution techniques for phased array radars such as optimum beamforming and MUSIC ignore the transmit beam pattern and work solely with the receiver outputs. However for directional transmit phased arrays which scan a relatively narrow beam over a restricted sector of interest ignoring the transmit beam pattern leads to model mismatch. The consequent losses can be mitigated by stacking the receiver outputs as the transmit beam is scanned over the sector of interest and modifying the steering vectors for the subsequent processing. This proposed hybrid approach can be interpreted as a MIMO virtual array system achieving higher beam output SNRs whilst still providing the MIMO ability to resolve more DOAs than conventional phased arrays. Numerical and simulation examples are presented to illustrate the stacked approach and to compare the different approaches to estimating the DOAs of uncorrelated signals.