We present an extension to network simulator ns-2 for simulation of smart antennas with maximize gain beamforming. Unlike some of the previous work on this topic, we use a realistic beamforming model with detailed radiation patterns. Our antenna framework can be used to evaluate the characteristics of beamforming under various conditions and can be combined with any MAC protocol with smart antenna interface. Exemplary, we implemented two MAC protocols, and results show that with beamforming overall throughput and packet delay can be improved. The magnitude of this improvement is of course dependent on the chosen protocol and scenario.