Simulated impedance bandwidths, gains, radiation patterns and SAR values of a helical and a PIFA antenna on top of different ground planes

In this paper the antenna performances i.e. impedance bandwidths, gains and radiation characteristics, including specific absorption rate (SAR) values, of two commonly used antennas, namely a helical and a planar inverted-F antenna (PIFA), on top of different ground planes are studied. The main idea of this study is to compare the performances of these two antennas when the size of the ground plane and the locations of the feeding and shorting points are altered. The Global System for Mobile communications (GSM) 900 system specifications are chosen as a starting point and then the free space impedance bandwidths, gains and radiation patterns are simulated by the method of moments (IE3D 7.0, Zeland Software Inc.) and SAR values by finite difference method (XFDTD 5.0, Remcom Inc.) using a homogeneous phantom. These results are finally compared and conclusions of optimal ground plane structures as well as differences between the two antennas are made.