A reflective multilayer polarization converter with switchable frequency band

A multilayer polarization converter operating in the reflection mode with a switchable frequency band is proposed, where the unit cell consists of layers of a polarizer, active frequency selective surface (AFSS), and metallic ground, separately. The polarizer layer is designed in the form of a periodic split circular loop structure. The AFSS layer is constructed by a three-layer second-order passband structure with PIN diodes loaded orthogonally on the top and bottom layers. In this design, the AFSS can be switched between the transmission and reflection modes by controlling the bias, resulting in a change in the effective permittivity of the dielectric substrate. The switchable polarization converter is verified by both simulations and experimental results. It is found that when the PIN diodes are in the ON/OFF-state, the proposal converter can change the linearly polarized wave from 9 GHz to 17.1 GHz and from 5.5 GHz to 11.6 GHz, respectively.