Compact broadband CPW-fed ZOR antennas with gradual change structures

Compact coplanar waveguide (CPW)-fed zeroth-order resonant (ZOR) antennas with broad bandwidth are presented in this paper. The ZOR characteristic is introduced by the composite right/left-handed (CRLH) unit cell on the CPW single layer substrate. The modified structure with a gradual change of the feeding part enables this impedance-matching property. Three prototypes of the designed antennas are fabricated to verify the predictions and the measured −10 dB bandwidths are all more than 30%. The features of easy fabrication and extended bandwidth have made the antennas valuable in wireless communications.