Signal design for a specified transmit beampattern, spatial ambiguity function for MIMO radar: A brief review of recent results

In phased-array radars, the transmitted waveforms from its different antenna elements are fully correlated resulting in a focused beampattern. On the other hand, MIMO (multiple-input multiple-output) systems with transmit array containing colocated elements produce omni-directional beampattern with uncorrelated waveforms transmitted from its antennas. In some applications, it might be desirable to synthesize a beampattern that is between these two extremes so that wide focus areas can be formed without wasting power in the directions that are of no interest. In this paper, we present a brief review of recent results on the signal design. Specifically, we first introduce briefly the transmit beampattern and spatial ambiguity function, and then illustrate through examples how the zero-lag cross-correlation matrix of the transmitted signals, R, impacts the transmit beampattern. Next, we describe the beampattern/spatial ambiguity function design, through the design of R, as an optimization problem, and illustrate this with a few examples. Once the desired R is found, synthesis of the waveforms from R, subject to certain practical constraints, will be outlined.