Using a Yagi Antenna in a Cell Phone Signal Booster System
By Dan · September 13, 2012
A yagi antenna is a specific type of directional antenna, which means that it sends and receives a signal from primarily one direction. A good way to visualize this is by thinking of a flashlight. The light from a flashlight shines in a narrow beam, only in the direction that it’s pointed. If you shine a flashlight on something close, it illuminates a small area, but if you shine it on something further away, the illuminated area is larger. In this same way, a yagi antenna transmits and receives radio signals from a single direction and the farther away the signal gets, the wider the beam becomes.
Since yagi antennas are designed to only send and receive from a single direction, they are able to transmit a much stronger signal than omnidirectional antennas and can also receive weaker signals making them ideal for situations where the existing cell phone signal strength is low. If you have a strong signal and need to send and receive signals in multiple directions, you would instead choose an omnidirectional antenna.
When used in a cell phone signal booster system, a yagi is most often used as the external antenna that is located on the outside of a building where the cell phone signal is strongest. Yagi antennas are designed for a specific frequency range so before purchasing, ensure that it will work with the same frequencies as the signal booster you’re using. All of the kits on UberSignal.com have properly matched antennas so you shouldn’t have any trouble. To lessen the chances of oscillation (feedback) make sure the yagi is not pointed over your own roof.
A Wilson 14 dB Gain 1900 MHz Yagi Antenna (301124)
Most of our cell phone signal booster kits are designed to amplify the signals of multiple cell phone carriers at the same time. That way, regardless of your provider, the system will just work for everyone’s cell phone. This will continue to work with a yagi antenna if the carrier’s towers are in the same general direction. However, if you want to support multiple carriers and their towers are in different directions from your building, a single yagi antenna can’t be pointed in multiple directions and won’t work properly. In this situation, you can either go with an omnidirectional antenna if the existing signal is strong, or you can use multiple yagi antennas, each pointed at an individual carrier’s tower. When using multiple yagis, they should ideally be mounted at least 10 ft apart and not pointed at each other to prevent any interference. Then use a signal splitter to combine the two antennas into one cable that can be attached to the amplifier.
Because a yagi is a powerful antenna, there may be situations where it can overpower the cell towers and cause your system to malfunction. All signal boosters contain circuitry to detect and prevent this from happening so if you see your signal booster shutting down or displaying a warning light, it may be because the signal is too strong (another possibility is that there is feedback between the inside and outdoor antennas). In this case, just point the yagi off to the side of the cell tower instead of directly at it. The further away from the cell tower you point the yagi, the weaker the signal it will receive which may solve your over-powering problem.
With any external antenna, it’s important to remember that it will be exposed to mother nature, which can be very tough on equipment. In particular, antennas are susceptible to lighting strikes since they’re made of metal and have some level of electricity flowing through them. Because of this risk, we always recommend using a lightning surge protector between the yagi and the amplifier. Another thing to consider is wind. Some yagis come in a plastic housing, which can catch more wind and put significant strain on the pole during wind storms. Always make sure the antenna is securely mounted to a pole and that the pole is securely mounted to your building or you may end up losing some equipment in the next storm!
If you have any questions about yagi or any other antennas for your cell phone signal booster system, please contact us and we’ll be happy to help.