Can I improve performance with an external antenna?

As a rule of thumb, an external antenna will improve the signal strength of a wireless network signal by at least 15 percent because it can be placed in a position free of obstructions to the signal path. The external antenna can be attached to either the access point (in which case it will increase signal strength to every network client) or to a wireless network adapter. If you can place external antennas on both ends of the link, the total improvement will be about 32.5 percent.

This assumes that the captive antenna and the external antenna have exactly the same characteristics. If the external antenna is directional, or if it has more gain than the captive antenna, the performance improvement could be even greater. On the other hand, many network adapters and access points use two captive antennas in a diversity system that constantly compares the signals from each antenna and selects the stronger one. In a noisy environment, a diversity antenna system might be more effective than a single antenna.