Window Function Design for Non-uniform MIMO Arrays

Antenna position errors caused by manufacturing accuracy limits lead to a great difference between the real and ideal models of antenna arrays in extremely high frequency (EHF) band MIMO radar with tiny physical elements and spacings. As the real array is a non-uniform array, the conventional window function fails when applied to non-uniform sampling data, which causes angular ambiguities and seriously degrades the performance of DOA estimation. Based on an advanced analysis of spectral distortion in non-uniform sampling, this paper introduces a method to design a specialized window function for non-uniform MIMO arrays, aiming to minimize the equivalent noise bandwidth (ENBW) while sufficiently suppressing the side-lobe-to-peak ratio of the window function's spectrum. The simulation results show the effectiveness of the optimized window function, which reduces angular ambiguities and thereby improves the performance of DOA estimation for non-uniform MIMO arrays.