Two Novel Low Mutual Coupling Sparse Array Configurations: Combining Multiple Uniform Linear Arrays and Additional Sensors

The mutual coupling (MC) effect between sensors is a critical factor in sparse array (SA) design, substantially affecting direction-of-arrival (DOA) estimation performance. In this paper, we propose two novel SA configurations by combining multiple uniform linear arrays (ULAs) and additional sensors: one consisting of four ULAs and one additional sensor (SA-4U1S), and the other comprising four ULAs and two additional sensors (SA-4U2S). The goal of these configurations is to mitigate the MC effect within the SA, while maintaining sufficient uniform degrees of freedom (uDOFs). Moreover, the positions of all sensors in both SA-4U1S and SA-4U2S can be uniquely determined through closed-form expressions. Theoretical analysis indicates that the MC effects of the proposed SA-4U1S and SA-4U2S are smaller than those of most existing SAs. Simulation results demonstrate that the proposed SA-4U1S and SA-4U2S exhibit superior DOA estimation performance.