[Antennas] Cell Phone

2002年12月11日 23:25:43 -0500

Some years ago I was working for a company doing hydraulic well fracturing
in the New Mexico Oil Fields (a procedure of pumping fluids under high
volume (200-4000 gal/min) and pressure (2000-12,000 psi) into new oil wells
so as to crack the rock open and so get more oil flowing, I ran a computer
monitoring truck. We had computer programs that would monitor fluid flow
rates and pressure and would calculate what was happening a mile down in the
well.
Occasionally we would send the live data back to the office via modem
connected to a Motorola bag phone so they could follow the progress of the
job. As we were often far out in the desert, far from a cell tower we often
used a very high gain commercially made beam antenna. I think the
manufacturer was Antenna Specialists.
My experience was that although there was some improvement it wasn't as
great as you would expect from a 20 element beam. I did a calculation of
the losses in the coax leading up to the antenna and found, as I expected,
that it almost equaled the gain of the antenna. Also, they used UHF
connectors instead of N connectors, giving even more loss.
One time when visiting the local cell phone company shop the tech (also a
ham) showed me an experiment he tried connecting such a beam antenna to a
UHF portable phone (home phone, not cellular). Said he could access his
portable phone from several miles away. (Just an experiment, of course, as
it isn't legal to connect an external antenna to a portable phone.)
So, my answer is that yes it will help but you will have to use very low
loss coax and keep the length as short as possible. Study up on 1.2 gig
antennas and you will get an idea of what is needed.
I also expect you will have trouble locating a modern cell phone that can
accept an external antenna. All you see in the cellular outlets are
micro-sized handsets. Offhand I would say you might be best trying an old
analog 800 MHz unit. I see them dirt cheap at every hamfest. That
certainly would be a lot cheaper then special ordering a new Motorola. Also
the bigger units will give the full 3 watts output, which I don't think the
handsets can do.
Phil, n6mly
----- Original Message -----
From: "Merv Stump" <[email protected]>
To: <[email protected]>
Date: 2002年12月11日 11:05:37 -0500
Subject: [Antennas] Cell Phone
> Has anyone attempted to extend the range of a cell phone by building a
gain
antenna?
> I have an older analog only phone which I think operates in the 800 MHz
range. The antenna is about 3 and 1/2 inches - (1/4 wave on 800 MHz?????).
I also have a newer phone which operates in either the 800 or 1900 MHz and
the antenna is approximately 4 and 1/2 inches (3/4 wavelength at 1900????
and close to 1/4 at 800????)
> I like to use the phone from home and sometimes the "cell" is marginal.
Any
ideas?
> Merv