Hi all,

My girlfriend's mother lives in an area with poor reception,
especially indoors. I recently hung a little metal bracket from
suction cups on her bedroom window, stuck one of those 3dB magnetic
mount cell antenna's intended for a car roof on it, and ran the wire
inside so that she could use the free long distance from home without
facing the Florida summer heat. It helps quite a bit, but still cuts
out.

I understand that when used as intended the antenna uses the roof or
trunk of your car as a ground plane or counterpoise. (Are these the
same thing?) Some websites recommend sticking the antenna on a square
foot sheet of metal, but as this is Florida in the summer, I think our
usual midday rainstorms might blow the whole over. I've also seen
some mention of a wire groundplane - just a piece of wire cut to the
proper proportion of a wavelength. This would probably stand up
better to wind, but I can't find many specifics for this application.
The cable and antenna are one piece, so I can't attack the coax
shielding directly to the ground plane, but I assume the base of the
antenna is a ground plate meant to lie parallel to the car roof and
couple with it like a capacitor. Or am I wrong? Does the antenna
need the only the mere proximity of a wire of proper length? I don't
know.

I've seen a product advertised that looks like what I want, called
Sputnik, but I'd really not buy anything else, especially when I could
make it myself.

So I guess I need a small ferrous plate to stick to the magnetic
bottom, to which I can solder the horizontal wires of the ground
plane, but I'm not sure what lengths these need to be, how to position
them, or how many to use.

I don't even know what wavelengths I'm dealing with. It's AT&T
wireless, and "digital, not GSM", which I assume means PCS, on a
Motorolla V60 color. Can someone tell me if I'm looking at 800 Mhz,
or 1900, or what?

I considered making a parabolic reflector, but I know neither the
wavelengths used nor the precision necessary. (Do I need to adjust it
for the specific channels used, both for sending or recieving, or can
I just use the center of the 1900 range as an estimate?) Anyway, it
would be even worse with the wind than a flat sheetmetal counterpoise.

If the wire ground plane isn't feasable, could someone give me or
point me toward some deteils on building a little yagi for cell phone
use?

Any direction at all would be appreciated. I have ZERO experience
with antennas or radio equipment. I have no idea if I'm even on the
right track.

Thanks in advance, Isaac

Isaac,
Higher does more good than a large groundplane/counterpoise,
and yes, they're the same thing (sort'a). Almost anything will work,
metal sheet/plate, wire, foil, does 'mother's house have rain gutters?
'Doc

In article , isaac
wrote:

I understand that when used as intended the antenna uses the roof or
trunk of your car as a ground plane or counterpoise. (Are these the
same thing?) Some websites recommend sticking the antenna on a square
foot sheet of metal, but as this is Florida in the summer, I think our
usual midday rainstorms might blow the whole over.

Pending advice from the specialists, I'd be tempted to try a wire mesh
groundplane - something like the stiff wire mesh used in (cake) wire
cooling racks, with 1/2 inch mesh.

I don't think the size would be that critical providing the radius was
similar to the length of the antenna. Connect the wire to the iron bar
to which the antenna is attached.

Harry.

Hmmm.. sounds like she just needs to get a standard land line.

--
73! de Andy KC2SSB
http://shorecogs.tripod.com
AIM: shorecogs

"isaac" wrote in message
m...
Hi all,

My girlfriend's mother lives in an area with poor reception,
especially indoors. I recently hung a little metal bracket from
suction cups on her bedroom window, stuck one of those 3dB magnetic
mount cell antenna's intended for a car roof on it, and ran the wire
inside so that she could use the free long distance from home without
facing the Florida summer heat. It helps quite a bit, but still cuts
out.

I understand that when used as intended the antenna uses the roof or
trunk of your car as a ground plane or counterpoise. (Are these the
same thing?) Some websites recommend sticking the antenna on a square
foot sheet of metal, but as this is Florida in the summer, I think our
usual midday rainstorms might blow the whole over. I've also seen
some mention of a wire groundplane - just a piece of wire cut to the
proper proportion of a wavelength. This would probably stand up
better to wind, but I can't find many specifics for this application.
The cable and antenna are one piece, so I can't attack the coax
shielding directly to the ground plane, but I assume the base of the
antenna is a ground plate meant to lie parallel to the car roof and
couple with it like a capacitor. Or am I wrong? Does the antenna
need the only the mere proximity of a wire of proper length? I don't
know.

I've seen a product advertised that looks like what I want, called
Sputnik, but I'd really not buy anything else, especially when I could
make it myself.

So I guess I need a small ferrous plate to stick to the magnetic
bottom, to which I can solder the horizontal wires of the ground
plane, but I'm not sure what lengths these need to be, how to position
them, or how many to use.

I don't even know what wavelengths I'm dealing with. It's AT&T
wireless, and "digital, not GSM", which I assume means PCS, on a
Motorolla V60 color. Can someone tell me if I'm looking at 800 Mhz,
or 1900, or what?

I considered making a parabolic reflector, but I know neither the
wavelengths used nor the precision necessary. (Do I need to adjust it
for the specific channels used, both for sending or recieving, or can
I just use the center of the 1900 range as an estimate?) Anyway, it
would be even worse with the wind than a flat sheetmetal counterpoise.

If the wire ground plane isn't feasable, could someone give me or
point me toward some deteils on building a little yagi for cell phone
use?

Any direction at all would be appreciated. I have ZERO experience
with antennas or radio equipment. I have no idea if I'm even on the
right track.

Thanks in advance, Isaac

On Mon, 12 Jul 2004 11:51:53 +0000 (UTC), Harry Whitfield
wrote:

In article , isaac
wrote:

I understand that when used as intended the antenna uses the roof or
trunk of your car as a ground plane or counterpoise. (Are these the
same thing?) Some websites recommend sticking the antenna on a square
foot sheet of metal, but as this is Florida in the summer, I think our
usual midday rainstorms might blow the whole over.

Pending advice from the specialists, I'd be tempted to try a wire mesh
groundplane - something like the stiff wire mesh used in (cake) wire
cooling racks, with 1/2 inch mesh.

A ground plane need not be solid, as long as the holes are enough
smaller that the wavelength.

I don't think the size would be that critical providing the radius was
similar to the length of the antenna. Connect the wire to the iron bar
to which the antenna is attached.

The size is not critical, but ideal would be a radius of 1/4
wavelength. For a 1/4 wave antenna without a loading coil, that would
be the same as the antenna length.

Do the calculation yourself, but 1/4 wave at 800 mHz is about 3.51
inches.

Mounting your antenna on a 7" diameter disk would be optimal. Perhaps
that will be easier mechanically to work with.



Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

If the groundplane as suggested doesn't do the trick, get an antenna
that's designed to be mounted on the rear window, rather than the roof.
That sort of antenna should be able to function properly without a
ground plane. Another tip for either kind of antenna is to move the
antenna in very small increments while watching the phone's signal
strength indicator. A distance of a few inches can make a big difference
when multipath propagation is present. If possible, find a general area
where the signal strength isn't overly sensitive to antenna placement.
If you can't, you either need to very carefully place it at a "sweet
spot" (and hope the spot doesn't move when the wind blows), or use a
directional antenna.

Roy Lewallen, W7EL

Isaac,
All these are acceptable suggestions, but if your antenna base is truly
magnetic, an inverted 1-pound coffee can makes a perfect ground plane.
Larger would be slightly better, but beyond that, "finding the sweet spot"
is probably the best advice of all. Make sure that the antenna matches the
band being used: I believe AT&T is 800 MHz for 'digital' in FL, therefore
you should have a 800 MHz antenna. Do a google search for Cellular Yagis if
necessary, but I find most of these at www.canyonriver.com, and
www.antenna.com.


Bill Radio NAØNA
Click for Western U.S. Wireless Reviews at:
http://www.mountainwireless.com


"isaac" wrote in message
m...
Hi all,


I understand that when used as intended the antenna uses the roof or
trunk of your car as a ground plane or counterpoise. (Are these the
same thing?)

I don't even know what wavelengths I'm dealing with. It's AT&T
wireless, and "digital, not GSM", which I assume means PCS, on a
Motorolla V60 color. Can someone tell me if I'm looking at 800 Mhz,
or 1900, or what?

isaac wrote in message
m...
Hi all,

My girlfriend's mother lives in an area with poor reception,
especially indoors. I recently hung a little metal bracket from
suction cups on her bedroom window, stuck one of those 3dB magnetic
mount cell antenna's intended for a car roof on it, and ran the wire
inside so that she could use the free long distance from home without
facing the Florida summer heat. It helps quite a bit, but still cuts
out.

I understand that when used as intended the antenna uses the roof or
trunk of your car as a ground plane or counterpoise. (Are these the
same thing?) Some websites recommend sticking the antenna on a square
foot sheet of metal, but as this is Florida in the summer, I think our
usual midday rainstorms might blow the whole over. I've also seen
some mention of a wire groundplane - just a piece of wire cut to the
proper proportion of a wavelength. This would probably stand up
better to wind, but I can't find many specifics for this application.
The cable and antenna are one piece, so I can't attack the coax
shielding directly to the ground plane, but I assume the base of the
antenna is a ground plate meant to lie parallel to the car roof and
couple with it like a capacitor. Or am I wrong? Does the antenna
need the only the mere proximity of a wire of proper length? I don't
know.

I've seen a product advertised that looks like what I want, called
Sputnik, but I'd really not buy anything else, especially when I could
make it myself.

So I guess I need a small ferrous plate to stick to the magnetic
bottom, to which I can solder the horizontal wires of the ground
plane, but I'm not sure what lengths these need to be, how to position
them, or how many to use.

I don't even know what wavelengths I'm dealing with. It's AT&T
wireless, and "digital, not GSM", which I assume means PCS, on a
Motorolla V60 color. Can someone tell me if I'm looking at 800 Mhz,
or 1900, or what?

"Classic" AT&T wireless was TDMA, on the 800 Mhz band

I considered making a parabolic reflector, but I know neither the
wavelengths used nor the precision necessary. (Do I need to adjust it
for the specific channels used, both for sending or recieving, or can
I just use the center of the 1900 range as an estimate?) Anyway, it
would be even worse with the wind than a flat sheetmetal counterpoise.

If the wire ground plane isn't feasable, could someone give me or
point me toward some deteils on building a little yagi for cell phone
use?

Any direction at all would be appreciated. I have ZERO experience
with antennas or radio equipment. I have no idea if I'm even on the
right track.

Thanks in advance, Isaac