A 2-bit Reconfigurable Metasurface With Real-Time Control for Deflection, Diffusion, and Polarization

In this paper, a 2-bit reconfigurable reflective metasurface (RRM) with multifunction for both far-field pattern and polarization performance is proposed. To facilitate the independent design of two orthogonal polarizations as well as the diode integration at the bottom, the radiation and phase shifting parts are designed separately. The top patch is designed to receive and re-radiate EM waves, which converts the wave states between free-space wave and guided wave. The bottom phase shifting structure is designed to switch four phase states with 90° interval for the reflected guided wave. An 8×8 RRM is designed and fabricated using the proposed 2-bit element. Driven by a field programmable gate array (FPGA), the RRM achieves real-time control for different functions of beam deflection, radar cross section (RCS) reduction, and polarization conversion. The measured results show that the steered beam from -30° to +30° can be obtained around 3.83 GHz with different coding matrices, and more than 10 dB RCS reduction from 3.70 GHz to 3.84 GHz can be achieved by properly distributing phase responses randomly. Moreover, a linear polarization (LP) to left-handed circular polarization (LHCP) conversion in the range 3.82 GHz-3.85 GHz and right-handed circular polarization (RHCP) conversion in the range 3.68 GHz-3.82 GHz are realized by switching all the PIN diodes ON and OFF.