A Second-Order L-Shaped Full Digital Receiving Sparse Array for Direction-of-Arrival Estimation

Full-digital multibeam antenna array is a potential candidate architecture for sixth generation (6G) communications in millimeter wave band. The implementation of the sparse receiving array can effectively mitigate the high cost associated with a full-digital array. A novel second-order L-shaped array (SOLSA) is proposed in this paper. The coverage and direction-of-arrival (DoA) estimation performance of SOLSA and other six conventional different array architectures are simulated and compared. It can be concluded from the simulation results that the performance of the DoA estimation is improved compared with a uniform L-shaped array (ULSA). The lowest root-mean-square error (RMSE) can be reached under the condition of the same order of magnitude of algorithm complexity. A sixteen-channel full-digital multibeam receiving array is implemented to verify the conclusions. The prototype is constructed by quasi-Yagi antennas, radio frequency (RF) receivers, intermediate frequency (IF) chains, and analog-to-digital converters (ADCs). The measured data is processed offline in MATLAB. The simulation and measured results indicate that the proposed SOLSA has excellent DoA estimation performance, low signal processing difficulty, and wide coverage. The SOLSA is suitable for a full-digital array with sparse receiving channels. The asymmetric array may find widespread potential applications in future communication and radar systems.