A broadband zeroth-order resonant (ZOR) antenna based on asymmetric coplanar waveguide (ACPW) is presented. By adopting the epsilon negative transmission line (ENG-TL), a zeroth-order resonance mode can be achieved. We employ an asymmetric coplanar waveguide structure which offers the design freedom to realize the broadband ZOR antenna, where the antenna's bandwidth is characterized by the equivalent circuit parameters. The antenna has the compact unit cell dimensions of 5 x 13.8 mm(2). The measured results show that the operating bandwidth is about 1050 MHz (1.90-2.95 GHz), and the peak gain and radiation efficiency are 2.46 dBi and 91% at zeroth-order 2.3 GHz. Owing to the characteristics of broad bandwidth, high efficiency, omnidirectional radiation, and easy manufacturing, the proposed ACPW ZOR antenna is very suitable for modern wireless communication systems (UMTS, WLAN, WIMAX, LTE).
