If you use your cell phone while travelling in your car, get a rooftop antenna & your battery life will show a significant improvement.

Most cell phones adjust the transmitter power to the minimum level necessary to maintain a good connection with the nearest cell tower. In fringe areas, the nearest tower might be some distance away, so your cell phone will find it necessary to crank out the full 300 milliwatts it's capable of producing.

The weak link is your cell phone's antenna. Newer phones all have internal antennas, the kind that don't protrude from the top of the case. They're very sleek, and they don't break off when riding around in your pocket, but they're not very efficient when it comes to converting transmitter power into an effective radiated signal. If you're inside your car, the metal automobile body also sucks away some of your signal, making it very difficult for your cell phone to transmit data to the cell tower. To compensate for all these inefficiencies, your phone has to run at maximum power to stay connected. Battery life is very short in rural areas.

The way to fight back is to get an external antenna and mount it in the middle of your car's roof. The antenna itself, when compared to the hidden antenna in your phone, is at least ten times more efficient than your phone's built-in antenna. Plus, it's outside the car, so it doesn't suffer the energy loss involved when the signal passes through the sheet metal of the car's body. Finally, mounting the antenna in the middle of the roof creates something called a "ground plane," which dramatically improves the radiation pattern of the antenna.

The end result is that a roof-top antenna is probably 100 times more efficient than your cell phone's internal antenna when used from inside the car. This means your phone can lower its transmitter power and still stay connected to rural cell towers, cutting way back on battery drain. Another bonus is that you'll be able to talk in places that were formerly "dead zones" because the external antenna allows you to connect with cell towers at a greater distance than with an internal antenna.

good to see ya on the other side

I don't own a cell phone but i couldn't help but wonder how the phone would receive the signal from the roof antennae. Your post makes a lot of sense, I hope no one in Chicago sees it, though... these people can not drive for beans and when they get on their cell phones; it's just like driving with those dodge'em/bump'em cars in the arcades... you'd swear they want to hit you.

The rooftop and/or glassmount antennae typically "receives" its transmission signal from the cable inside the car. IE you plug your cellphone into a docking station or docking cable inside your car, and that then sends the cellphone's signal into a powerbooster that is powered by the car battery.

that in turn sends the signal down the wire inside the car to near the base of the rooftop antennae. The rooftop antennae then receives the signal from the interior of the car and re-radiates it from the roof.

This all works because antennaes are essentially giant tuning forks. And like any tuning fork, if you put a tuned signal source near it, the tuning fork starts to resonate and amplifiy the original signal.