Flexible Extended Nested Array with Multiple Subarrays Achieving Improved Degrees of Freedom

This paper proposes a new extended nested array geometry with enhanced degrees of freedom (DOF) and a hole-free difference co-array. The proposed flexible extended nested with multiple subarrays (f-ENAMS) configuration is constructed by splitting the dense subarray of the nested array (NA) into four subarrays and relocating them on either side of the NA configuration to maximize the DOF. Several conditions are provided for a specific design to guarantee the continuity of the difference co-array (DCA). Compared to other sparse arrays, f-ENAMS offers improved DOF, which leads to high-resolution DOA estimation. Simulation examples are presented to demonstrate the superiority of the proposed f-ENAMS array configuration.