An Enhanced Augmented Coprime Array With Low Mutual Coupling and High DOFs

Coprime array (CA) has gained significant attention due to its high degrees of freedom (DOFs) and large array aperture. Previous researches have focused on improving coprime arrays, but few studies have successfully combined a large array aperture, low mutual coupling, and high DOFs with the number of array elements. In this paper, we propose a novel semi-symmetrical augmented coprime array (SSACA) that strategically positions sensors by arranging M-subarrays and symmetric N-subarrays. This design reduces redundancy lags, and increases DOFs, continuous DOFs, and array aperture, thereby mitigating mutual coupling effects and improving angular resolution for the direction of arrival (DOA) estimation. We derive closed-form expressions for the DOFs, continuous DOFs, and array aperture of SSACA. Simulation results demonstrate that the proposed SSACA outperforms the existing studies regarding higher DOFs, reduced mutual coupling effects, and lower root mean square error (RMSE) in similar application scenarios, particularly in strong mutual coupling scenarios.