Wideband asymmetric coplanar waveguide antenna using composite right/left-handed transmission line

A broadband asymmetric coplanar waveguide antenna is designed. In this design, two periodical composite right/left-handed transmission line (CRLH-TL) unit cells were chosen to generate three resonating modes. The broadband characteristic of this antenna can be achieved by combining the first-negative-order resonance, zeroth-order resonance, and first-positive-order resonance of CRLH-TL. A prototype structure of our proposed antenna has been fabricated and tested. The dimensions of the antenna are 30.0 x 40.0 x 1.6 mm(3), which corresponds to 0.19 lambda 0 ${\lambda }_{0}$ x 0.25 lambda 0 ${\lambda }_{0}$ x 0.01 lambda 0 ${\lambda }_{0}$, where lambda 0 ${\lambda }_{0}$ is the free-space wavelength at 1.88 GHz. The measured band in which S-11 is below -10 dB ranges from 1.80 to 3.75 GHz with the fractional bandwidth of 70.27%. The radiation patterns of the proposed antenna are highly consistent throughout the operating band, which covers the band of WiMAX, with the measured average peak gain of 2.77 dBi and radiation efficiency of 86.63%.