Antennas impact how a signal is transmitted or received.
An antenna can not create power, it can only shape the signal. An antenna offers signal gains in one aspect at the cost of other aspects.
Antennas are typically directional, where the signal gains are concentrated in one direction, or omnidirectional, where the signal is optimized for reception from all directions.
The WiFi Pineapple ships with standard omnidirectional antennas. These are the most appropriate for typical use cases where the goal is to detect access points and clients in the surrounding area.
Antenna gains are typically measured in dBi, or "dB over isotropic", a theoretical perfect antenna with no gain.
The higher the gain, the more the signal is impacted.
Remember - more gain is not always better! There is always a trade-off with signal gain!
Omnidirectional antennas are typically found on access points, WiFi interface cards, and of course the WiFi Pineapple.
An omnidirectional antenna is designed to radiate in a roughly spherical shape.
As the gain of an omnidirectional antenna increases, the horizontal coverage increases but the vertical coverage decreases.
Excessively high gains on omnidirectional antennas can be detrimental! Above approximately 9dBi of gain, the vertical range of the antenna can become so limited that clients and access points more than a foot or two higher or lower than the device are invisible!
Directional antennas can be used to shape the signal in a specific direction. Typically directional antennas cover an arc measured in degrees.
Directional antennas can be useful for targeting a specific device or area, but often are not the best solution for general data gathering.