Design of X-band reconfigurable frequency selective surface with high isolation

In this paper, a bandpass reconfigurable frequency selective surface (FSS) with high isolation at passband, which can reconfigure the operating frequency by using a PIN diode for the X-band, was designed. The proposed surface is composed of four-legged loaded elements, inductance stubs, and a bias grid to supply power. By controlling the electrical length of the unit cell using the forward bias and zero bias of the PIN diode located between the cross-shaped pattern and the stub, the operating frequency can be reconfigured. By controlling the stub length, the switching range of the operating frequency can be controlled. Based on the design results, two types of reconfigurable FSS were constructed, and their measured transmission losses, obtained using the rectangular waveguides WR-75 and WR-90, were compared with simulation results. The comparison showed very similar results.