A New Low-Redundancy Restricted Array with Reduced Mutual Coupling
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In array signal processing, a fundamental problem is to design a sensor array with high degrees of freedom (DOFs) (or low-redundancy) and reduced mutual coupling, which are the main features to improve the performance of direction-of-arrival (DOA) estimation. A sensor array is called low-redundancy if the ratio R=N(N-1)/(2L) is approaching the Leech's bound 1.217≤ R_opt≤ 1.332, where N is the physical sensor number and L is the maximum inter-sensor spacing of the sensor array. Up to now, the best known infinite classes of low-redundancy arrays (LRAs) satisfy R≤1.5. The objective of this paper is to propose a new LRA configuration with R<1.5 for any N≥18. The new array preserves all the good properties of existing sparse arrays, namely, the different co-array is hole-free, and the sensor locations are uniquely determined by a closed-form expression as a function of the number of sensors. Notably, compared to existing sparse arrays, the proposed array can significantly reduce the effects of mutual coupling between sensors, by decreasing the number of sensor pairs with minimum inter-spacing to the lowest number 1. Numerical simulations are conducted to verify the superiority of the new array over other known sparse arrays.
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