In , "Leland C. Scott"
wrote:


"Landshark" wrote in message
om...
That all depends on your goals. The typical dual antenna setup, when
done
right, generates maximum signal strength to the front and to the rear.
The
signal strength to the left and right is considerably reduced. The same
applies to your receive signal strength as well.


Um, sorry wrong Leland, it makes the signal more omnidirectional.

If done correctly, spaced - phased - good ground plane, it works as I
described.

http://www.bellscb.com/cb_radio_hobb.../antarray.html



Long hual truckers normaly are concerned with communicating with other
truckers on the road. Those truckers are going to be either in front or
behind them on the highway. Thus it makes sense to maximize the signal
in
those directions, and thus the popularity of the setup.

If your more interested in general communications in any direction then
you
really don't want a dual antenna setup. What you want is an antenna
location
near the center of the truck, which will as nearly as possible, give you
a
uniform signal in all directions. The site you picked, on the tool box,
would be a good one.


Again, wrong Leland.

No. The site above has not only a discussion about antenna patterns, but the
antenna field pattern plots to prove it. I can supply some EZNEC 4.0
simulation files to prove same if you want.


Everyone will think I'm insane for saying this, but Landshark has it
right. In order for co-phased antennas to achieve that ideal figure-8
pattern they must be nearly ideal antennas, which CB antennas are not.
Landshark's link explains why this happens. I wouldn't expect any
significant improvement in the omnidirectional characteristics of
dualies (as the site claims), but I do know they don't provide any
noticable directional gain.






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