One of the most promising global telecommunication technologies capable in boosting the capacity and requirements of present and future wireless systems one such standard, IEEE 802.16 (WiMAX) for wireless metropolitan area networks. It supports wide coverage area and high data rate compared to cellular and Wi-Fi network. In recent times by adding omni directional antenna tends to bring the new functionalities in the advancement of WiMAX technology. This paper investigates the potential of omni directional antennas in context to mobile WiMAX network. The performance evaluation based on wide variety of simulation scenarios were built in WiMAX networks. The proposed technique has been designed and simulated using the QualNet 6.1 network simulator.