Radial CRLH-TL-Based Dual-Band Antenna With Frequency Agility

A novel reconfigurable radial composite right/left-handed transmission line (CRLH-TL) is proposed and used in a dual-band antenna with frequency agility. Varactors are used to tune the TL dispersion properties. Using the 10 dB return loss criterion, the proposed antenna has a stable relative band of 4.1% fully covering the 2.4-2.5 GHz ISM band, and a tunable operating band from 3.05 to 3.89 GHz fully covering the 3.1-3.8 GHz WiMAX band. A frequency tuning range of 24.2% is obtained in this higher band. The lower and higher resonances work at the 0 mode and 1 mode, respectively, resulting in an omni-directional pattern for both the operating bands, due to the circular symmetry. A prototype antenna is fabricated, and the simulations and experiments match well, proving the validity of the new concept.