Transmit beamforming design for two-dimensional phased-MIMO radar with fully-overlapped subarrays

We investigate a subaperturing technique for two-dimensional (2D) transmit arrays within the context of multiple-input multiple-output (MIMO) radar. Specifically, we investigate the performance of transmit beamforming using fully overlapped subarrays of a 2D transmit array. As reported for linear array of antennas, this 2D transmit array exploits the advantages of the MIMO radar technology without sacrificing the coherent processing gain at the transmit side provided by the phased-array concept. In order to achieve high coherent processing gain, a weight vector should be designed for each subarray to steer the transmit beam in certain 2D sector in space. This is achieved by solving a convex optimization problem that minimizes the difference between a desired transmit beampattern and the actual beampattern produced by the 2D array of antennas, under a constraint in terms of uniform power allocation across the transmit antennas.