Augmented improved nested array with enhanced degrees of freedom and reduced mutual coupling effect

To reduce mutual coupling of an improved nested array (INA), the authors propose an augmented improved nested array (AINA) by splitting the dense subarray of the INA into two parts and rearranging one of them on the right side of the last element in the INA, which enhances the number of unique lags in difference coarray and reduces the number of element pairs with small separations. The closed-form expressions for the physical element locations, the range of consecutive lags and the number of unique lags are derived for any given element number. It is indicated that the AINA possesses higher degrees of freedom and less mutual coupling than the common sparse arrays. Numerical simulations verify the superiority of the proposed configuration. In this letter, the authors proposed an augmented improved nested array (AINA) configuration for direction of arrival (DOA) estimation. The AINA can provide more unique lags, and smaller weight functions compared with the common sparse arrays. The closed-form expressions for element locations and degrees of freedom are derived. Numerical simulations demonstrated the effectiveness of the AINA in terms of DOA estimation performance in the presence of mutual coupling. image