Document Type

Theses, Ph.D


Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence


Electrical and electronic engineering

Publication Details

Thesis submitted for the award of Doctor of Philosophy to School of Electrical and Electronic Engineering, Technological University Dublin, July 2015.


This thesis presents research on printed circularly-polarized monopole antennas and their application in reconfigurable monopole antennas. The proposed circularly-polarised monopole antennas benefit from advantages such as small size, low-cost, low-profile and simple designs. The first part of this thesis introduces three printed circularly-polarized monopole antennas for global navigation satellite systems and Wi-Fi applications. The primary focus is on the ground plane which is used as a radiating component in realizing circular-polarization. It is shown that by employing the ground plane as a radiator results in a wide axial ratio bandwidth. The radiation patterns of the antennas and their relationship with antenna ground plane sizes is investigated. Then, a frequency-reconfigurable monopole antenna with circular-polarization for wireless local area networks and global navigation satellite systems is presented. The ground plane current distribution, rearranged by a switch, enables the right-hand circularly-polarized band to move in frequency from the GPS band to Wi-Fi frequency bands.

Finally, a simple polarization reconfigurable printed monopole antenna for wireless applications is described. Once again, with the help of the ground plane and by changing its current distribution, linear-polarization, right-hand or left-hand circular-polarization is realized. The polarization agility is controlled by two PIN diodes, which alter the ground plane surface currents. The antenna is one of the few polarization-reconfigurable monopole antennas reported in the literature. For all the presented antennas, parametric studies of key geometric parameters are given for clear understanding of the circular-polarization radiation mechanism.