Multi-objective Design of Uniform Sparse MIMO Arrays

Abstract

The problem of multi-objective design of sparse MIMO arrays for better multitarget detection capabilities is considered. A novel approach for efficient utilization of the antenna design resources; namely, the number of available array elements, and array aperture are studied for the angular beamforming performance metrics such as, beam width, the peak to sidelobe ratio (PSLR), and grating lobe limited field of view. The limiting constraints, the physical size of elements, and mutual coupling are also considered. Thinning of fully populated uniform MIMO antenna arrays to form effective uniform sparse arrays (USA), as the term proposed here, are examined as for their capability of improving usable field of view (uFOV), beamwidth (BW), and peak-to-side lobe-ratio (PSLR) using fewer physical antenna elements, simultaneously. Sparse arrays require much less array elements to outperform uniform linear (ULA) and rectangular arrays (URA) for their beamwidths. Further, a rigorious design procedure considering the physical size limitations is currently unavailable. Here, we present a practical design architecture of such a uniform sparse array under multiple contradicting objectives. Angular resolution performances of the novel uniform sparse arrays are compared with the standard ULA and URAs. It is shown that design of an array with small inter-element spacings avoiding any grating lobes is possible even when the physical size of the elements are very large. Expanding the available elements to a much larger apertures provides much better angular resolution. However, it is also shown that these advantages come with the cost of increased side lobes. Both the simulated and the measured results demonstrate the superiority of the proposed uniform sparse array design compared to classical fully populated uniform arrays.