A Compact Wideband Frequency Reconfigurable Antenna for Cognitive Radio Applications

A compact wideband frequency reconfigurable (FR) antenna is designed for the cognitive radio (CR) applications in this paper. The antenna covers 4.33 to 7.21 GHz frequency range when tuning the capacitances of the varactors. By introducing the planar periodic slow wave structure on the patch, the dimension of the antenna is drastically reduced to 4 × 4 mm ² . Simulated results indicate the antenna holds satisfying radiation performance with low cross-polarizations. In applications, the proposed antenna is suitable for the portable devices with CR capacities.