Design of a 1-Bit Programmable Coding Unit Cell Beamforming Metasurface

Traditional phased array antennas rely on costly phase shifters to steer beams by manipulating the phase of induced currents in each antenna element. In this study, we introduce a 1-bit coding metasurface as an alternative to traditional phased array antennas for beam control and modulation of electromagnetic waves. The metasurface operates at 5.8 GHz and consists of digitally controlled unit cells, each incorporating a pin diode. These diodes enable binary coding states of "1" and "0" with a significant 180-degree phase difference. The unit cell, with a dimension of 0.81λ x 0.81λ, comprises two metal patches separated by the pin diode on an FR-4 substrate. Simulation results demonstrate the distinct behavior of the metasurface, with the off-state exhibiting a reflection amplitude response of 1.8dB and the on-state showing a reduced amplitude due to on-resistance. The far-field patterns obtained from the simulations clearly indicate a 90-degree change in the radiation pattern between bit "0" and bit "1." This innovative design offers a cost-effective solution for beam control and versatile electromagnetic wave modulation, making it suitable for various applications, including beamforming in radar and communication systems.