Generation of Sum and Difference Radiation Beam with a 2-bit Polarization-Dependent Metasurface

This paper describes the generation of sum and difference radiation beams with a 2-bit polarization-dependent (PD) metasurface. A single-layer and cross-shaped dipole unit cell is proposed to implement the PD metasurface. By appropriately optimizing the dimensions of the unit cell, it is readily able to offer a 2-bit reflection phase for two orthogonal (horizontal and vertical) polarizations independently. A horn antenna is adopted as the feed source to illuminate the PD metasurface. Sum and difference radiation beams can be achieved when the phase shifts of the PD metasurface are appropriately imposed in horizontal and vertical polarizations by mechanically rotating the PD metasurface 90 degrees. For demonstration, a circular PD metasurface composed of 232 unit cells is implemented at the millimeter-wave band. The simulations reveal that the PD metasurface-based scheme can offer stable sum and difference radiation beams from 24 to 28GHz, where the null depth levels at broadside direction are all below -20dB. The gains of the sum and difference radiation beams are 23.6dBi and 22.1dBi at 26GHz, respectively.