Greetings, Even though this is the basic group, my knowledge is less than basic but there are some pretty advanced folks here. So here's my question: How to increase range of cell phone while in remote areas. I have a little motorola flip phone. It has a stubby little antenna that works great around the city and I-5 corridor but has spotty reception on the island I live on north of Seattle. But I'm always hearing about stranded hikers using cell phones to call for help in the Cascade mountains around the Seattle area. So I was wondering what kind of antenna booster could be made so that when I fall down a hill and scrape my knee I can call for rescue. I thought about getting a car antenna but don't know if the car has to be present for it to work properly. Anybody know the answers? Thanks, Eric R Snow
Being literally on a mountain is a huge advantage to any radio system in that you have a direct line of sight 'connection' to a cell tower.
Since you're asking this question, a safe answer is that you simply can't build one yourself. However, if you do a little Googling you'll find that commercial amplifiers are available. But keep in mind the following: Just adding an amplifier lets the cell tower hear YOU better, but doesn't allow you to hear IT any better whatsoever! The reason that "antenna boosters" can improve performance is due to the fact that the cell towers output much more power than your phone (often tens of watts vs. a decent fraction of a watt). The other reason they work is that they always use an external antenna, which are electrically bigger (more gain) and which can typically be placed higher up (e.g., on a roof) and therefore can also "see" the towers better. Finally, with a _directional_ antenna, you've got the one thing that'll let you hear the tower better.
Most car antennas are simply dipoles using the card as the ground plane (more or less), so using a car antenna on a decent sized slab of sheet metal is fine. These antennas aren't directional (since this isn't practical in a car that's pointed in arbitrary directions from minute to minute!), but for a home installation you can special order directional antennas.
This is what I'd do:
-- Get a cheap external 'car' antenna for the phone. Put it up as high as you can somewhere, see if it helps.
-- If not, and assuming you have line of site to a cell tower, get a directional antenna. So-called "Yagis" are standard and can easily quadruple the workable distance between the phone and the tower.
Although you can use those antennae, keep in mind that the cell system actually controls the output power of your phone - when you are close,
*your* phone is commanded to reduce it's output power, although the cell may or may not reduce *it's* power. If your problem is related to being in a very poor signal area, then using an antenna with a greater physical area (but the same electrical area - there's a lot of trickery in antenna design) may well help.
In some parts of the world, people get billed for the expense of frivolous rescues.
Anyway, to answer your original question, I wouldn't want to try to add a home-brew antenna to a cell phone, unless you know of some way to get proper matching and everything. I seriously doubt if you have access to adjust the output circuit. It might be worthwhile to look into some kind of long-range phone, or even get a ham license. :-)
In my experience, most (but certainly not all) cell phones have antenna connectors on them (often blocked by a rubber plug or something, however), just waiting to have a proper connector/coax cable plugged into them. (Usually MMCX or similar...)
Yes, my phones antenna screws out. I'll check and see if there is a longer range antenna that screws right in. Id been so het up on making my own, just for fun, that I didn't even remember that the stubby little antenna unscrews. Thank you and the others that have replied. Cheers, Eric
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