Radar Angular Resolution Enhancement Based on Dynamic Reflective Metasurface Generated Mirror Array

The angular resolution of phased-array radar is essential for applications, including multitarget detection, real aperture imaging, and so on. Because of various practical limitations, improving the angular resolution by further increasing the size of the phased array is, however, challenging. In this article, we propose a method to enhance the angular resolution of radar by using a mirror array generated by a dynamic, reflective metasurface (DRM), which reflects incoming electromagnetic waves in a specific direction by adjusting the phase shifts of its reflection elements. First, we establish the model of the mirror array obtained from the configurable reflected signal of the DRM and then derive the Cramér-Rao lower bound (CRLB) for angular resolution by jointly processing the signals from both the mirror array and the physical array. Next, we propose a block majorization-minimization (BMM)-based method for passive beamforming with the DRM under the minimax criterion. Third, we present methods for separating the DRM reflected signal from the direct return signal, as well as for extending the array aperture to enhance angular resolution. Finally, the performance of the proposed approach is assessed through simulations and validated using a 24-GHz array radar and DRM.