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Wireless mesh networks are becoming increasingly popular. Most proposed mesh algorithms are evaluated using simulation. Simulations frequently oversimplify real world scenarios and can lead to results that are significantly different. Thus, although it is more difficult to run controlled experiments in already deployed real-world networks, it is important to understand how proposed improvements perform under these realistic scenarios. Several authors have suggested the use of directional antennas, but their merits have only comprehensively evaluated in simulators. Roofnet is an unplanned 802.11b wireless mesh network deployed by MIT and is constructed primarily of omni-directional antennas. We use measurements to evaluate performance gains from using a directional antenna on this network. Other factors such as user location and number of hops to the gateway are considered. Using throughput, latency, and streaming video tests, this paper examines the end-to-end performance of the network. Five working locations were chosen in total and three permitted directed performance comparisons between directional and omni-directional antennas. The directional antennas improved throughput by 21% reduced roundtrip times by 15% quicker round trip times. The directional antenna also provided more consistent video quality, and stabilized faster.