A Tunable K-Band Reflector

This letter presents a concept for a surface exhibiting tunable reflectivity that operates within the K-band using varactor diodes. Thereby, the impedance of a two-layer metasurface is controlled through lumped components at its back side and not at the front, where discrete elements would scatter the incident wave. A reflector's design, verification, and modeling through an equivalent circuit as well as full-wave simulations are presented in detail. Finally, the tunable reflection parameters of the surface as well as its reflection beam pattern under different biasing conditions are shown.