Bandwidth Improvement of Monopole Antenna Using π-Shaped Slot and Conductor-Backed Plane

摘要

A novel design of small monopole antenna with enhanced bandwidth property for ultra-wideband (UWB) applications is presented. The antenna consists of an ordinary square radiating patch and a modified ground plane with π-shaped slot and conductor-backed plane. By cutting a π-shaped defected ground structure (DGS) and also by embedding a π-shaped conductor-backed plane in air gap distance, additional third and fourth resonances in 12 and 14.5 GHz are excited and much wider impedance bandwidth can be produced. By using these modified structures, the usable upper frequency of the antenna is extended from 10.4 GHz to 15.1 GHz. Simulated and measured results show that the antenna design exhibits an operating bandwidth (S11 ? -10 dB) from 2.89 to 15.1 GHz, which provides a wide usable fractional bandwidth of more than 135%. The proposed antenna has an ordinary square radiating patch, therefore displays good omnidirectional radiation patterns even at higher frequencies. The antenna configuration is simple, easy to fabricate and can be integrated into UWB systems.