A compact octagonal-ring monopole antenna for super wideband applications

Abstract

A compact monopole super wideband antenna has been designed and fabricated in this study. The proposed antenna consists of an octagonal-ring shaped patch with a stub positioned on the top right corner of it to enhance the impedance bandwidth. Further improvement is ensured by optimally shifting both the patch and feed line away from the center line, and introducing a notch on the ground plane. The fabricated antenna covers the frequency band from 2.59 to 31.14 GHz with a reflection coefficient of |S-11| <= - 10 dB. It has a bandwidth of 28.55 GHz, fractal bandwidth percentage of 169% and bandwidth ratio of 12.02:1. Omnidirectional radiation characteristics are observed over the operating bandwidth in the far-field measurements. Furthermore, the far-field radar cross section measurement of the antenna is also simulated on PC and relatively low values are obtained through the operating bandwidth. Presented antenna has a relatively small size (40 x 40 x 1.01 mm(3)) and exhibits good gain and efficiency characteristics in comparison to studies with similar bandwidth.