Boresight gain optimization of an UWB monopole antenna using FDTD and genetic algorithm

Printed planar monopoles are promising ultra wideband (UWB) antenna and can be easily integrated in communication systems by fabrication onto printed circuit boards. These planar monopoles become popular for wireless communication due to their broad bandwidth and appropriate radiation pattern. However because of the dependence of the antenna gain and the antenna aperture, as the frequency increase, the wavelength decreases, the boresight gain decreases and its variation is very large. In this paper, a new UWB elliptical monopole antenna with a printed structure fed by a microstrip line is presented. The antenna is analyzed by using the finite-difference time-domain (FDTD) method and the parameters of the shape of the antenna are determined by utilizing the genetic algorithm (GA). Through a novel ground structure of the substrate, the boresight gain equals to approximately 2.4dB in the frequency band ranges from 3GHz to 9GHz. Details of the proposed antenna design and simulated results are presented and discussed.