1 x 3 Microstrip Line-fed Metal-plated Split U-shaped Omnidirectional Ultra-wideband Monopole Antenna

In this article, a parallel metal-plated split U-shaped omnidirectional ultra wideband (UWB) antenna fed by a novel 1x3 microstrip line is proposed. Printed monopole antennas fabricated on a substrate offer impedance bandwidth which can cover UWB. However, radiation pattern varies significantly over the bandwidth. The cross polar component increases with frequency and the pattern degrades from the desired omnidirectional characteristics. Omnidirectional radiation bandwidth can be increased significantly by decreasing the substrate thickness and using substrate material of low dielectric constant. With the use of the proposed feeding arrangement, parallel metal-plated split U-shaped monopole antenna shows omnidirectional radiation pattern. The proposed metal-plated structure using foam as dielectric is designed, fabricated, and tested. The measured VSWR is < 2 over 3.1 to 10.6 GHz frequency band. The antenna offers high efficiency, stable gain, small group delay variation, and its radiation patterns indicate its suitability for UWB applications.