A reconfigurable frequency-selective surface for dual-mode multi-band filtering applications

A reconfigurable single-layer frequency-selective surface (FSS) with dual-mode multi-band modes of operation is presented. The proposed structure is printed on a compact 10 × 10 mm² FR4 substrate with the thickness of 1.6 mm. A simple square loop is printed on the front side while another one along with two defected vertical arms is deployed on the backside. To realise the reconfiguration, two pin diodes are embedded on the backside square loop. Suitable insertion of conductive elements along with pin diodes yields in dual-mode multi-band rejection of applicable in service frequency ranges. The first operating mode due to diodes’ ‘ON’ state provides rejection of 2.4 GHz WLAN in 2–3 GHz, 5.2/5.8 GHz WLAN and X band in 5–12 GHz, and a part of Ku band in 13.9–16 GHz. In diodes ‘OFF’ state, the FSS blocks WLAN in 4–7.3 GHz, X band in 8–12.7 GHz as well as part of Ku band in 13.7–16.7 GHz. As well, high attenuation of incident waves is observed by a high shielding effectiveness (SE) in the blocked frequency bands. Also, a stable behaviour against different polarisations and angles of incidence is obtained. Comprehensive studies are conducted on a fabricated prototype to assess its performance from which encouraging results are obtained.