Investigating Stacked-Ring Based Cells for Phase Shifting Surfaces

This paper investigates a stacked-ring based unit cell design for near-field phase-shifting metasurfaces developed for beam-steering applications. The unit cell has two dielectric layers sandwiched between three thin patterns of conductive material. Each of the three conductive patterns has a circular ring of varying sizes to produce the required spatial phase variation across the metasurface. To validate the performance of the unit cell, a metasurface was designed to tilt the beam of a $4\times 4$ microstrip array. The numerical simulations predict that the array beam can be tilted by an angle of 28.8° without severe degradation, verifying the unit cell phase-shifting characteristics.