It is important to consider a number of factors when choosing an antenna for your AP. To choose the right components, you'll need to know:
Frequency band: Ensure the antenna supports the AP's operational bands.
Antenna gain: Choose a gain that meets your needs while avoiding overshoot and interference.
Beam width and direction: Do you need an Omni-directional antenna for 360-degree coverage? Or a directional antenna for a more focused, long-distance coverage?
Radiation patterns: Consider an antenna's coverage pattern.
Installation environment: Consider where you plan to deploy the antenna - indoor or outdoor? On a ceiling, wall, or pole? Make sure that you select an antenna that matches the environment.
Connectors and cable length: Choose an antenna that is compatible with your AP and that it has a long enough cable.
Obstacles: Geographic obstacles such as walls or the terrain can affect antenna performance.
Indoor and outdoor antennas differ in two important ways:
Outdoor antennas are weather sealed to protect them from the environment. Because of this extra protection, outdoor antennas are typically more expensive than those rated for indoor use. Outdoor antennas can be used for indoor applications, such as freezers and cooler where moisture is common. But indoor antennas should not be used in outdoor applications.
Outdoor antennas typically have a Type N Male connector for connecting to a lightning arrestor. It is strongly advised that you use a lightning arrestor with an outdoor antenna.
Most indoor antennas are mounted directly to the AP's connectors. But you may want to position the AP a significant distance away from the antenna.
In these situations, various adapters and cable extensions are required. Keep the following points in mind:
The connector on the AP
The connector on the antenna
The spectrum being implemented
Signal loss due to multiple connectors and long cable lengths