Design of a 1-bit Coding Broadband Metasurface

A novel design of l-bit coding metasurfaces tuned by a PIN diode is presented in this paper. The designed metasurface consists of two T-shaped metal patches connected by a PIN diode, two layers of dielectric substrates, and a metallic ground. Over frequencies from S to 19.65 GHz, the reflection coefficient is higher than 0.85 when diode in both on and off states, and the reflection phase difference between two states is about 18$0^{\circ}\pm 37^{\circ}$. The designed structure has broadband characteristics that relative bandwidth reaches 84.27%. In addition, the DC bias circuit of the PIN diode is etched on the metasurface. Therefore, no additional feeding lines are introduced, decreasing the impact on the active metasurface.