Henry,
Don't waste your time, won't work as intended. Did
you really ask someone where to put/stick that other
half of the antenna??
'Doc

On Wed, 16 Jul 2003 21:15:13 -0500, 'Doc sent into the
ether:



Henry,
Don't waste your time, won't work as intended. Did
you really ask someone where to put/stick that other
half of the antenna??
'Doc
Nice restraint on your part Doc :}
Dan, N9JBF
Amateur radio - What a hobby!
Remove left x for direct reply

When a car body is not available to provide the "other half" of the antenna,
you provide the other half of the dipole.

http://user.mc.net/~jdewey/sleeve_di...iew_of_car.jpg

A commercial version is also available

http://www.antenna.com/lm_cat/lmrpg10.html


"Henry Kolesnik" wrote in message
...
I wonder if radiated energy would increase measureably if one were to try
to
balance mobile whip antenna by having another whip connected directly to
the
body and tuning it. If it would, how would one locate, size, and tune
it?
tnx
hank wd5jfr

When the "co-phased" CB whips were introduced into the market years ago,
I saw it for the master stroke it was -- a whole lot of CB'ers who in
the past would have bought only one antenna now bought two, effectively
doubling the revenue of the antenna manufacturers. A brilliant move. And
the placebo effect guarantees that the users will see superior results.
Makes everyone happy, manufacturers and users alike.

Sounds like we're on the nexus of another breakthrough.

Roy Lewallen, W7EL

Assuming one whip is pointing up, which way is the other whip pointing?

The way I saw it done, the other whip was at the other end of the car
and also pointing up. I have no knowledge of whether this was actually
useful, but apparently the user thought it was.

In which case, it is a phased vertical array, not a dipole. With
a spacing of 1/8WL, one can get 4 dB gain that way.
--
73, Cecil http://www.qsl.net/w5dxp



Actually, I read about this in Don Johnson of Screwdriver antenna fame's
book on mobile radio operation. IIRC, the folks experimenting with it
put the second whip on the far end of the car - tied to the frame, ie
grounded - not driven. When tuned to resonance an increase in RF current
in the car body was noticed and I think they also saw about a 3db
increase in radiated signal. I imagine it's not very popular because of
the difficulty of tuning two antennas instead of one, and the visual
aspect of a second large antenna on the vehicle. It just isn't that
practical even for a 3 db increase in signal.

It wasn't presented as being a dipole or any form of phased array. Just
as empirical data that picked up along the way that was interesting.

73,
Kevin, WB2EMS

Roy Lewallen wrote:
When the "co-phased" CB whips were introduced into the market years ago,
I saw it for the master stroke it was -- a whole lot of CB'ers who in
the past would have bought only one antenna now bought two, effectively
doubling the revenue of the antenna manufacturers. A brilliant move. And
the placebo effect guarantees that the users will see superior results.
Makes everyone happy, manufacturers and users alike.

Sounds like we're on the nexus of another breakthrough.

They could have done a lot better if they had co-phased them front
to back instead of side to side.
--
73, Cecil, W5DXP

W5DXP wrote:

In which case, it is a phased vertical array, not a dipole. With
a spacing of 1/8WL, one can get 4 dB gain that way.

In your dreams.

Roy Lewallen, W7EL

Roy Lewallen wrote:
W5DXP wrote:
In which case, it is a phased vertical array, not a dipole. With
a spacing of 1/8WL, one can get 4 dB gain that way.

In your dreams.

I'm dreaming of The ARRL Antenna Book, 15th edition, page 8-6. Spacing 1/8WL,
phasing=135 deg, Gain = 4.1 dB. Remember, this is for two 10m verticals mounted
in line with the vehicle, not one on each side of the vehicle. It is essentially
a two element vertical beam with a cardioid radiation pattern and a large
front/back ratio.
--
73, Cecil http://www.qsl.net/w5dxp



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Kevin,
It would also be directional, and probably usless
at least 50% of the time on a mobile...
'Doc

Cecil, is that not a driven collinear array?

Deacon Dave, W1MCE

W5DXP wrote:

Roy Lewallen wrote:

W5DXP wrote:

In which case, it is a phased vertical array, not a dipole. With
a spacing of 1/8WL, one can get 4 dB gain that way.


In your dreams.


I'm dreaming of The ARRL Antenna Book, 15th edition, page 8-6. Spacing
1/8WL,
phasing=135 deg, Gain = 4.1 dB. Remember, this is for two 10m verticals
mounted
in line with the vehicle, not one on each side of the vehicle. It is
essentially
a two element vertical beam with a cardioid radiation pattern and a large
front/back ratio.