A Low-Complexity and Wideband-Reconfigurable Active Frequency-Selective Surface With Flexible Polarization Controllability

In this letter, a novel active frequency-selective surface (AFSS) with a wide reconfigurable operation band is proposed. Based on the switchability of p-i-n diodes and the flexibility of biasing strategies, the proposed AFSS can be controlled to operate in four modes: dual-polarized ultra-wideband shielding, transverse electric (TE)- or transverse magnetic (TM)-polarized wave selection, and dual-polarized bandpass filtering. The advancement of the proposed AFSS lies in its third-order wideband switchable frequency responses and the simple, one-layer bias design with no extra feeding network. The symmetric structure of the proposed AFSS makes it polarization-insensitive and polarization-independently controllable. Simulation results illustrate that the proposed AFSS achieves a wideband high transmittance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ {\bf {\vert}} {S}_{\bf {21}} \bf {\vert \geq }$</tex-math></inline-formula> −0.5 dB) window covering 7.78 GHz to 12.50 GHz with a fractional bandwidth of 46.55% for TE-polarization and 7.84 GHz to 12.52 GHz (45.97%) for TM-polarization under normal incidence in bandpass filtering or corresponding polarization selection modes. In the shielding mode, the proposed AFSS can achieve an ultrawide stopband from 0 GHz to 20 GHz under normal incidence. A prototype of the proposed AFSS has been fabricated and measured. The measurement results are in high consistency with the simulation ones.