Compact Coplanar Waveguide (cpw)-fed Tun- Able Wideband Resonant Antennas Using Metamaterial Transmission Line

A wideband resonant antenna loaded with coplanar waveguide (CPW) epsilon negative transmission metamaterial line (ENG MTL) unit cells is proposed. The CPW geometry provides high design freedom, and the metamaterial resonant antenna is designed on a CPW single layer where vias are not required. The novel ENG unit cell on a vialess single layer simplifies the fabrication process. The dispersion analysis of the metamaterial unit cell reveals that increasing right hand capacitance and left hand inductance can decrease the half-wavelength resonance frequency, thus reducing the electrical size of the proposed antenna. Based on the proposed ENG MTL unit cell, the wideband antenna is verified by a commercial EM simulator HFSS11 and developed. Comparing the measured performances with those resonant antennas, it is noticed that the proposed antenna achieves high bandwidth and further size reduction, higher efficiency and easier manufacturing. The realized antenna has a compact size of 0.32λ0×0.20λ0×0.012λ0 (26.6mm×16. mm×1 mm) at 3.65 GHz, and operates over the frequency ranges 3.38–4.23 GHz suitable for WiMAX applications. Good agreement between the simulated and measured results is obtained.