Frequency Reconfigurable Slot Antenna Using Metasurface for Cognitive Radio Applications

A dual-port antenna system designed for cognitive radio applications is presented in this study. The structure comprises of an ultra-wideband (UWB) sensing antenna and a reconfigurable communicating antenna. The former is a stepped slot structure with an offset feed, which covers the whole UWB frequency band from 3 to 10.6 GHz, whereas the latter is a dual-band slot antenna (DBSA) fed with a fork-shaped microstrip-line feed and loaded with two identical layers of meandered metasurfaces (MSs). Frequency agility is realised by rotating the MS layers for the DBSA antenna. The dual-band communicating antenna has three switchable states with tuning ranges of 28 and 45% in the lower- and upper-frequency bands, respectively. The degree of isolation and gain in all three states are appreciable. The proposed structure is fabricated and measured, which has a good agreement with the simulated results.