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Posted by Jerome Hansen on October 23, 2010
Here are some basics on how cellular repeater systems work.
A basic cell phone repeater system consists of:
The Outside antenna communicates with the towers, the signal runs through a low-loss cable to the cellular amplifier. A Wilson Smart Tech amplifier can add 65db of power and send it through another cable to the inside antenna, which radiates the signal through the air, to your device.
Gains-Losses: Everything here is designed to take the power (measured in dB) from outside and maximize it on the inside.
That’s usable, since your phone can pick up a signal as weak as -105dB
Now, at the end of the whole process, you have -13dB coming from your antenna. That is more than enough power for your phone to read the signal very clearly. How far will that signal go? If you can pick up signals as weak as 105dB from your phone, then (105dB – 13dB = 92dB) you hae a 92dB excess. So, if we lost less than 92dB, we could still use the phone. It takes about 90 feet of air travel to lose that much power when running at 1900Mhz (800Mhz goes much further), which means you can step 90 feet from the antenna and still use your phone (just barely). Going through objects however, that number may change.
When you split the signal between two antennas, expect the coverage to be split by the same ratio.
That’s the basics of how these things work, slightly geared toward your particular situation.