Polarization Diversity with Genetic Parallel Printed Dipole Antennas for Bluetooth and WiMAX Applications

Multipath propagation effect degrades usually the wireless system performances. Antenna diversity in one of the several methods that have been studied to mitigate this phenomena. This technique can overcome the multipath fading improving the overall performance of communication system. In order to study the impact of the wireless channel and perform antenna diversity, two parameters must be evaluated: the mean effective gain, and the correlation coefficient between the antennas. Parallel printed dipole antennas have been successfully used in mobile base station development, showing either broadband or multiple-band properties besides its low cost. However, polarization diversity parameters have not been analysed since these antennas have not been yet considered in mobile devices and diversity applications. In this paper, a polarization diversity schema comprised of two dual-printed dipole antennas for bluetooth and WIMAX applications operating in 2.4-2.4835 GHz and 3.5 GHz frequency bands are presented. Genetic algorithm optimization (GA) is applied first, to a classical dual band printed dipole antenna schema, second to a pre-fractal tree parallel printed dipole to achieve a more compact radiator. Frequency performance of both antennas is introduced showing a VSWR< 1.5 for a input impedance of 50 Ohms. Later on, a diversity antenna based on the pre-fractal configuration is studied in terms of mean effective gain (MEG) and correlation coefficient for indoor and outdoor scenarios. Results shows that MEG is nearly the same in both environments with a low correlation between the elements which means that diversity gain can be achieved using this schema.