I saw a demonstration of an RF detector being brought close to a mobile phone. As the detector was moved away, the number on it dropped to zero. How can that be? Shouldn’t there be some RF signal from the phone all the way to the cell tower, so that the phone can communicate with the tower?

Question

I saw a demonstration of an RF detector being brought close to a mobile phone. As the detector was moved away, the number on it dropped to zero. How can that be? Shouldn’t there be some RF signal from the phone all the way to the cell tower, so that the phone can communicate with the tower?

In: Technology

Answer 1

You may have heard of the inverse square law. Each time you double the distance, the power drops by four times. The power isn’t actually zero. It’s just low enough that it’s below what the detector will indicate. (Cell phones work at incredibly low received power levels, both at the phone and from phone to tower)