A band- and frequency-reconfigurable circularly polarised (CP) filtenna that exhibits good selectivity and out-of-band rejection in both its wideband and continuously tunable narrowband states is reported for cognitive radio (CR) applications. The filtenna provides two switchable operational states: A wideband state from 2.52 to 3.53 GHz for sensing and a tunable state of narrowband states from 2.44 to 3.19 GHz for communications. The corresponding 3-dB axial ratio bandwidths completely overlap these impedance bandwidths. A single PIN diode is utilised to switch between these two operational states to achieve the band-reconfigurable performance. Two varactor diodes are employed to realise the frequency-reconfigurable performance by facilitating a continuous shift of the narrowband states over the operational communication frequencies.
ASJC Scopus subject areas
- Electrical and Electronic Engineering