Who knows cell phones and antennas?

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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

Re: Who knows cell phones and antennas?


> 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.

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.

> 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.

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.

> I thought about getting a car
> antenna but don't know if the car has to be present for it to work
> properly.

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.
-- If not, start looking at amplifiers.

---Joel





Re: Who knows cell phones and antennas?


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.

Cheers

PeteS



Re: Who knows cell phones and antennas?



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4. If you're going hiking in the wilderness, bring along proper equipment.
4a. Don't jump off cliffs. ;-)

Good Luck!
Rich


Re: Who knows cell phones and antennas?



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The antenna, of course, is to be part of the proper equipment. As far
as jumping off cliffs go, I'll do whatever I want! So There!
Cheers,
Eric

Re: Who knows cell phones and antennas?


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you
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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. :-)

Good Luck!
Rich



Re: Who knows cell phones and antennas?


Rich,

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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...)

---Joel



Re: Who knows cell phones and antennas?


On Thu, 5 May 2005 17:20:58 -0700, "Joel Kolstad"

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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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