"Leland C. Scott" wrote in message
...

"NetWeasel" wrote in message
news
Hi all,
I've got an aluminum tool box in the back of my pickup truck. It's the
usual type that spans the bed right behind the cab.

I'm thinking that it might make a good antenna mounting point. I don't
want
to drill into the body of the truck, but I wouldn't mind putting a
couple
holes in the toolbox.

Understandable.

I have two questions. The first is: If I mount brackets to the tool
box,
will I need some sort of ground strap to connect it to the frame of the
truck to give me a good ground?

Yes. For a quarter wave antenna the ground plane needs to be at least a
quarter wavelength in size too for the antenna to function correctly. The
truck body forms part of the ground plane while the capacitance of the
truck
body to earth ground forming the rest of the ground plane in simple terms.

The second is: Will I see any real world improvement in performance by
using dual antennas?

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.

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.

I like the look of the trucks that I see with antennas on each side of
the
bed box. It's nice for a balanced appearance.

If looks is what he wants, fine but I think he wants some sort
of performance.


You have to make up your mind, good looks, or good performance. Your
typical
passenger truck is not wide enough, you need 9 feet, to properly setup a
dual antenna system.

I also understand that it's
a bit trickier to adjust SWR with dual antennas.

Correct, it's a bitch.

It can be.

I wouldn't be against
using one as an antenna and simply using the other one to balance out
the
look of the truck (although, I guess some folks might think that's
silly).

You said it, not I.

Your truck. You have to drive it.

Good Luck.

He'll need it.



--
Leland C. Scott
KC8LDO



If you have stake bed holes, go to your local muffler shop,
have them bend a sort of "roll bar" for the antenna. Make
a mount in the center of the bar for the antenna. Then
mount it in the stake bed holes, drilling through the inner
bed, into the antenna bar for bolting it up.

Here's a pretty good link on how
antenna's work.

http://www.signalengineering.com/ult..._antennas.html

Landshark


--
Treat people as if they were what
they ought to be and you will help
them become what they are capable
of becoming.