Abstract
A simple circular-ring planar-monopole antenna, with a compact size of 26 x 28 mm(2), fed by an offset-microstrip line, is proposed. The antenna is composed of a circular-ring radiator and a ground plane with a small rectangular slot cut along the upper edge for ultra-wideband (UWB) operation. Studies of the antenna are carried out using computer simulation. Prototype of the antenna is used for verification of the simulation results. Results show that the antenna has an impedance bandwidth of more than 132% (from 3.7 to more than 18 GHz) for the standing wave ratio of less than 2 (voltage standing wave ratio, VSWR <= 2), a stable omnidirectional radiation pattern and an average peak gain of 3.97 dBi across the UWB, making the antenna a good candidate for use in UWB communications. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2283-2288,2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26295