Design of active frequency selective surface

In this study, three different design of active frequency selective surface are presented. The first design has a single layer structure on a 1.6 mm thick FR-4 dielectric material. The unit cell consists of circular structure, patch and PIN diodes and is capable of switching between transmit and reflect modes in the 2.1 – 2.2 GHz band. The second design has a double layer structure on 1.6 mm thick FR-4 dielectric material. The unit cell consists of circular structure and PIN diodes and has the ability to operate independently of each other in the 2.3 – 2.9 GHz and 5.4 – 6.2 GHz bands and to switch between transmission and reflection modes in these bands. Both designs showed insensitivity up to different polarization and a certain angle of incidence. The equivalent circuit model method was used in the design process. The first design was manufactured and measured with the aid of a waveguide. In the third design, the effect of different PIN diode configurations on the radiation reflected or transmitted by the frequency selective surface was examined.