2D-MIMO Radar: A Method for Array Performance Assessment and Design of a Planar Antenna Array

In this article, a method for the assessment of the performance and for the design of a 2-D-array for multiple input multiple output (2-D-MIMO) radar applications is presented. The proposed approach is based on the analysis of the ambiguity function associated with the array. Such analysis leads to the definition of an area in the 2-D-angular field-of-view of the radar, denoted as ambiguity-free region, characterized by a low probability to obtain ambiguities in direction of arrival estimation. Simulations of a basic 2-D-MIMO array are used to explain the proposed method, which is then employed as the main criterion for the optimization of a 2-D-MIMO sparse array composed of four transmitters and eight receivers. The optimization is performed through a genetic algorithm. The resulted element positions guarantee an ambiguity-free region span in the azimuth and elevation angles greater than 120° and angular resolutions of 8° and 5.9° on the azimuth and elevation angles, respectively. The optimized positions are then used to realize a 2-D-MIMO sparse array that is integrated in a radar system operating at a center frequency of 76.5 GHz. Such an array is calibrated, and comparisons between the simulated and measured ambiguity functions show the effectiveness of the proposed method.