Depending on your wireless access point, you can add an external antenna to it. For example, in Chapter 12, "Buying a Wi-Fi Access Point or Router," I showed you an example of an external antenna attached to an access point.
Antennas are used with access points to add range to the access point's radio broadcast. They are also an integral part of a Wi-Fi network that covers a substantial area. The use of antennas with your access points can greatly reduce costs in deploying a wireless local area network because you can use fewer access points than you would need without the antennas.
Directional antennas can be deployed with great effectiveness with wireless bridges. For example, you could use wireless bridges combined with directional antennas to connect the wireless access points serving two different buildings in a campus, thus making both buildings part of the same wireless network.
If you are planning to use antennas as part of your Wi-Fi network deployment, it's important to understand the different kinds of antennas that are available. (You also need to make sure to buy access points that come with plugs for external antennas.)
An important part of deploying a Wi-Fi network is doing a site survey, which takes into account the topography and obstacles of the area that needs to be "unwired" and comes up with the best plan and layout for access points and antennas.