Asymmetric Coplanar Waveguide (ACPW) Zeroth-Order Resonant (ZOR) Antenna With High Efficiency and Bandwidth Enhancement

A novel low-profile zeroth-order (ZOR) antenna is presented. The feature of ZOR based on periodic structures is employed to reduce the antenna size, while these antennas generally suffer from narrow bandwidth. A single-layer asymmetric coplanar waveguide (ACPW) structure is proposed to realize a bandwidth-extended ZOR antenna, where the antenna bandwidth is characterized by an equivalent circuit model. The ACPW structure not only provides the design freedom, but also overcomes the design constraint of the traditional CPW. The ACPW ZOR antenna is verified by both full-wave simulations and experiments. As an advantage of the proposed method, the size of antenna is reduced, and the resonant frequency of zeroth-order mode is 1.94 GHz with radiation efficiency of 85%, measured 10-dB fractional bandwidth up to 10.3%, and omnidirectional peak gain of 2.3 dBi.