An asymmetric coplanar waveguide (ACPW) resonant antenna based on the composite right/left-handed transmission line

Abstract

An asymmetric coplanar waveguide (ACPW) resonant antenna based on a composite right/lefthanded transmission line (CRLH TL) is presented. The proposed antenna consists of an asymmetric coplanar waveguide feeding line and mushroom unit cells. Based on the fundamental structure, an improvement on the antenna is implemented. Two novel structures including a strip-shaped extended ground plane and a rectangular extended ground plane are studied. The antenna with the strip-shaped extended ground plane exhibits bandwidth enhancement characteristics. The operating bandwidths with 10 dB return loss over 210 MHz (1.57–1.78 GHz) is obtained. The fractional bandwidth is enhanced from 0.31% to 12.5%, an improvement factor of approximately 40.32. Meanwhile, the antenna with the rectangular extended ground plane presents broadband features. From measured results, the impedance bandwidth over 3.19 GHz (2.65–5.84 GHz) was occupied. It covers WiMAX 3.5/5.5 GHz and WLAN 5.2/5.8 GHz bands, and therefore could well apply to WiMAX/WLAN systems. Further, the radiation patterns, peak gain and radiation efficiency are also presented and discussed.