Cellular (800Mhz) antennas/boosters?

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
User avatar
kheston
Posts: 348
Joined: Wed Dec 03, 2003 1:01 am
Location: CA
Contact:

Cellular (800Mhz) antennas/boosters?

Post by kheston » Sun Nov 15, 2009 9:33 am

My mountain place has very limited cellular signal. We can make calls if we're in a certain area, but then only when standing on one leg with one's fingers crossed. Even still, dropped calls are unavoidable. I need a way to make my 1/2 watt device(s) reach further.

There are products out there by Wilson, zBoost and Cyfre that claim to solve the problem, but I'm not convinced. I purchased one and tried it (~$200 range) and wasn't impressed. Before I go out and pay more money on something bigger, I wanted to ask whether anyone could recommend a good book or two that I might read before I spend.

Specifically, I'd like to know what my options are when I don't have line-of-sight and am likely +14 miles at best from the nearest tower. Will a yagi or anything directional work? Can I get more gain out of going with a 1/4 or half wave antenna (at 800Mhz half wave is still practical, right)?

The zBoost unit I bought looked as though the main antenna (external) was simply a PVC pipe with a wire in it. The 30ft cable from the external to the booster unit was simple RG6. Does anyone still build their own antennas?

Suggestions?
Kurt - SF Bay

User avatar
MrAl
Posts: 3862
Joined: Fri Jan 11, 2002 1:01 am
Location: NewJersey
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by MrAl » Sun Nov 15, 2009 1:52 pm

Hi there,


Back when CB radios were becoming hugely popular (long, long, time ago) i was just a
kid and couldnt afford a decent CB antenna and couldnt reach the people across two
towns my family was good friends with, so i read up on antenna design and built
by own. It ended up being some 16 feet high and i installed it on the roof of the
house and it was vertical so it was pretty high. Anyway, i ended up getting those
people and then some. The moral of the story is that you can build your own
antenna and get a lot out of it for a fraction of the cost it would otherwise cost
to get something else already built.
Also, you can construct it so that you can vary it a little to try to get the length(s)
fixed at their best values.

For CB the frequency is rather low and so required very long elements (1/2 inch
copper tubing) but for such high frequency as a cell phone you would need much
shorter lengths of tubing to try this idea out. You can start with 1/4 inch tubing
i guess but 1/2 inch is better. Might want to start with a simple full dipole and
see where that gets you.
Antennas with more elements provide more gain so you might want to think about
cutting several lengths and working with them to see what you can get out of it.
It wont cost much to try this, and it is interesting in it's own right, and if you
can get enough gain you'll be happy.

There are probably antenna designs all over the web. I dont have my antenna
design handbook handy so i cant help too much except with the basic approach.
The basic dipole as you probably know starts out being one wavelength with each
half wavelength on each side and the cable connects to the center of the two,
one wire to one side and the other to the other side with the ground side down
and the other side up. Pipe clamps and a center non conductive piece keep it
in shape. The larger the pipe diameter the more the total length gets shorter
as that affects the right length somewhat, although i dont have the design
formula in front of me.
LEDs vs Bulbs, LEDs are winning.

User avatar
reloadron
Posts: 519
Joined: Sat Jun 28, 2008 8:57 am
Location: Cleveland, Ohio
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by reloadron » Sun Nov 15, 2009 3:22 pm

I would venture a guess a yagi may work for you. This is a pretty simple design guide. Today with PVC pipe being so cheap and available it makes for putting a yagi together pretty easy. Something else that may be worth a look is the cantenna designs popular with 2.4 GHz WiFi but designed for the 800 to 900 MHz regions. Both the YAGI and Cantenna designs should offer pretty good directional gain. Anyway just a few guesses to add to the mixing pot.

Ron

Robert Reed
Posts: 2276
Joined: Wed Nov 24, 2004 1:01 am
Location: ASHTABULA,OHIO
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by Robert Reed » Sun Nov 15, 2009 5:19 pm

This would be an opportune time to hook up to a TV antenna for experimentation. And I am talking someones throw away antenna. It should be strictly for the UHF bands only and complete with balun. Some mismatch will be encountered by virtue of its 75 ohm impedance, but if a discarded one is handy, it might be worth a try just out of curiosity. Also the ARRL manual has a chapter devoted to UHF antenna construction and a late (forgot the year)issue can be downloaded. The UHF amateur band is in the 450 MHz region and I don't know what the next higher band is for them, but the dimensions could be scaled accordingly. Unfortunately, unless you live aboard a space station, height is important----height,height, height!

User avatar
Externet
Posts: 1837
Joined: Fri Feb 01, 2002 1:01 am
Location: Mideast USA
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by Externet » Sun Nov 15, 2009 6:18 pm

Hello Kurt.
Does your telephone have a antenna connector ?
You could build a yagi, there is many examples and discussions on the web. Increasing gain by adding elements means only pennies extra. Vendors, one of them is :
http://www.cellantenna.com/Antennas/yagi.htm
They also sell 1 and 2 Watt fixed units, but that does not guarantee you will receive any better the weak celltower signal.
Miguel
- Abolish the deciBel ! -

User avatar
CeaSaR
Posts: 1710
Joined: Sat Nov 08, 2003 1:01 am
Location: Phoenixville, PA USA
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by CeaSaR » Sun Nov 15, 2009 9:58 pm

My $0.02 worth...

The link I found for the Sirius radio question:
Tons of antennae calulators, etc.
You might find something over there.

CeaSaR
Hey, what do I know?

User avatar
kheston
Posts: 348
Joined: Wed Dec 03, 2003 1:01 am
Location: CA
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by kheston » Mon Nov 16, 2009 4:17 pm

If I buy or build an antenna, will I still need an amplifier to drive it during transmission? Without an amp, only my receive gain will improve, correct?
Kurt - SF Bay

User avatar
Bob Scott
Posts: 1192
Joined: Wed Nov 20, 2002 1:01 am
Location: Vancouver, BC
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by Bob Scott » Mon Nov 16, 2009 4:56 pm

kheston wrote:If I buy or build an antenna, will I still need an amplifier to drive it during transmission? Without an amp, only my receive gain will improve, correct?
Don't use a transmitter amplifier. You should not need it. If your antenna has gain, the gain is applicable to both receive and transmit.

I am assuming that the transmit and recieve circuitry use the same antenna.
-=VA7KOR=- My solar system includes Pluto.

User avatar
Externet
Posts: 1837
Joined: Fri Feb 01, 2002 1:01 am
Location: Mideast USA
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by Externet » Mon Nov 16, 2009 7:20 pm

A TX active amplifier would not improve reception, to the contrary, would impair it somehow, as would need also a larger duplexer to handle the extra power. Do not go into TX amplification nor RX preamplification. -As Bob says- Those are full duplex.
Miguel
- Abolish the deciBel ! -

User avatar
CeaSaR
Posts: 1710
Joined: Sat Nov 08, 2003 1:01 am
Location: Phoenixville, PA USA
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by CeaSaR » Mon Nov 16, 2009 9:02 pm

I second Bob. Antenna gain is bi directional. If you can pick up the signal clearly, you should be able to
transmit just about as clearly. Always some losses, but the reception is a good indicator of transmission.

Best you can hope for is to find an antenna (design) that offers good gain and directionality. Then get
that up high enough to point accurately towards the nearest tower, unobstructed. While RX/TX amps
can make the signal "louder", you'll get noise along with whatever weak signal you may pick up. Worst
case scenario is you would amplify nothing.

"Dad, I'm going over to the tree to make a call. Can you turn off the generator so I can hear, please?"

:mrgreen:
CeaSaR
Hey, what do I know?

User avatar
CeaSaR
Posts: 1710
Joined: Sat Nov 08, 2003 1:01 am
Location: Phoenixville, PA USA
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by CeaSaR » Wed Nov 18, 2009 8:06 pm

kheston wrote:Specifically, I'd like to know what my options are when I don't have line-of-sight and am likely +14 miles at best from the nearest tower. Will a yagi or anything directional work? Can I get more gain out of going with a 1/4 or half wave antenna (at 800Mhz half wave is still practical, right)?
Well, from the link I gave you earlier comes this page: N3DNO's Antenna calculator.
At the bottom is the calculator for 1/4, 1/2, 7/8 and full wave vertical antennae. At 800 MHz, a full wave is
only 1' 2-1/16" long. You can also build a Dipole or 3 element Yagi from the info on that page. They are calc'd
at 1/4 wave, but you can double or quadruple the measurements to get 1/2 and full wave sizes and still be
relatively small. I'd try that first, if you can get access to an external antenna jack on your phone. Besides,
it gives you an excuse to DIY something else! :wink:

Of course you can poke around the original link (DXZone.com) and see what else they have in the way of info.
Seems to be quite a bit available through them.

CeaSaR
Hey, what do I know?

User avatar
kheston
Posts: 348
Joined: Wed Dec 03, 2003 1:01 am
Location: CA
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by kheston » Wed Nov 18, 2009 10:43 pm

CaeSar,

One of the antennas I have is ~7" long. The calculator you pointed me to shows this must be a 1/2 wave antenna. Pretty cool!
Kurt - SF Bay

k7elp60
Posts: 226
Joined: Wed Dec 05, 2001 1:01 am
Location: Ivins, UT
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by k7elp60 » Sat Nov 21, 2009 12:17 pm

Here is a website of a company that manufacturers cell phone range extenders. I read that their equipment can extend the range to about 50 miles from a cell tower.
http://www.wilsonelectronics.com///////////
This is a link that tells some more.
http://www.wilsonelectronics.com/////// ... yfreAd.pdf

Ned

SETEC_Astronomy
Posts: 582
Joined: Tue May 09, 2006 12:44 am
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by SETEC_Astronomy » Sat Nov 21, 2009 2:05 pm

Have you heard of a Femtocell before? Depending or your telephone or Internet provider it might be an option for you. I think At&t is the only US carrier offering them at the moment but Verizon is expected to offer them soon and possibly others soon after.

User avatar
CeaSaR
Posts: 1710
Joined: Sat Nov 08, 2003 1:01 am
Location: Phoenixville, PA USA
Contact:

Re: Cellular (800Mhz) antennas/boosters?

Post by CeaSaR » Sat Nov 28, 2009 7:26 am

SETEC_Astronomy,

Femtocells would be an option if there were any utilities around, and if that was the case there would most likely
be a cell tower closer than ~14 miles (LOS)!

Kheston,

So you were out there, huh? Did you take your antenna with you? Did it work? Any luck at all?
Inquiring minds want to know....

CeaSaR
Hey, what do I know?

Post Reply

Who is online

Users browsing this forum: No registered users and 4 guests