What material for antenna?
 

Guys and gals,

I'm working on assembling a groundplane antenna for my truck and am
wondering what materials to use. I know copper is likely the best, but
since I've got 1/8th inch steel rods laying around, I was wondering if I
could use those for the ground radials? I'm using the whip off an old
magmount for the transmitting element, but that's all of that material I
have handy. I'm not terribly concerned with the rust as I plan on painting
the whole assembly anyway.

I'm sure I can get some aluminum rod or brass/bronze rod at a local welding
shop if they would be better materials, rf wise.

Jeremy Becnel
KC5TEK

I'm working on assembling a groundplane antenna for my truck

Hi Jeremy, I guess you are assembling a mobile antenna for your truck. The
groundplane for it can be the metal body of the truck. No need to provide
"ground radials", although a groundplane at VHF, mounted on a truck has been
spotted by some folks.
Just use a simple 1/4 wavelength whip at the transmitting frequency, connect
that to the center conductor of your coax, and securely bond the coax shield to
the metal body of the truck. I would not paint. The mounting details are
usually the most difficult.
73 Gary N4AST

Well, for the one I'm building it is designed to have the round radials so
I'm doing my best to follow the builder's plans.

Jeremy

You can use any material that will conduct . The main thing to look at is
will it stand up and be mechanically sound. While you could use 1/4 inch
copper rod, if it is more than about 6 inches long it would bend out of
shape with a small ammount of wind.

"Jeremy Becnel" wrote in message
...
Guys and gals,

I'm working on assembling a groundplane antenna for my truck and am
wondering what materials to use. I know copper is likely the best, but
since I've got 1/8th inch steel rods laying around, I was wondering if I
could use those for the ground radials? I'm using the whip off an old
magmount for the transmitting element, but that's all of that material I
have handy. I'm not terribly concerned with the rust as I plan on
painting
the whole assembly anyway.

I'm sure I can get some aluminum rod or brass/bronze rod at a local
welding
shop if they would be better materials, rf wise.

Jeremy Becnel
KC5TEK

Jeremy, KC5TEK wrote:
"I`m not terribly concerned with rust as I plan on painting the whole
assembly anyway."

My 2-meter groundplane uses a GM telescoping car antenna as a radiator
and steel shelf-support channel from Home Depot as radials. These are
solid rust after many years and they still work fine.

Groundplanes are best for fixed locations unless you are using a vehicle
body or the like for your groundplane in a mobile application.

Commercially, the simple whip antenna worked against a car body has
almost universal acceptance.

For workboats to get a little height for greater line-of-sight we used
coaxial antennas. The vertical whip was half a diploe. A brass tube
skirt served as the other 1/4-wave part of the vertical dipole. It could
be elevated as high as convenient and worked as well as a groundplane
but with no risk of poking out an eye on a tossing and turning boat. My
ARRL Antenna Book has no construction article for the coaxial antenna. I
wonder why?

Best regards, Richard Harrison, KB5WZI

Well, for the one I'm building it is designed to have the round radials so
I'm doing my best to follow the builder's plans.

Jeremy, Just follow the builders plans. You have not provided enough
information to really get any informed help on the group. Not sure about
"round radials".
Good luck on your project, I would like to know how it turns out.
73 Gary N4AST

My mistake, I should've included the url for said plans.

http://members.aol.com/k5oejerry/vhf_vert.htm

The reason I'm wanting to go with the steel is for durability versus the
builder's 10 gauge copper wire. I seem to enjoy taking a simple design and
making it more 'pretty' for lack of a better term.

Jeremy
KC5TEK

Jeremy Becnel wrote:

My mistake, I should've included the url for said plans.

http://members.aol.com/k5oejerry/vhf_vert.htm

The reason I'm wanting to go with the steel is for durability versus the
builder's 10 gauge copper wire. I seem to enjoy taking a simple design and
making it more 'pretty' for lack of a better term.

Jeremy
KC5TEK

The requirement for the radials in the case shown at
the URL is because the antenna is elevated and
designed for hitting satellites. For normal low angle radiation a simple
magmount using the vehicle body as a groundplane would work.
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Jeremy,
The 'radials' aren't really necessary if you mount the
antenna directly to the vehicle's body (metal car body is
the ground). The whole point of the antenna at the URL
is that he didn't want to drill any holes in his vehicle.
If that bothers you too, then follow the directions.
The rods you have will probably work as well as anything
else you can find. The difference in conductivity between
your rods and copper just isn't worth worrying about. The
difference in durability ~is~ worth worrying about!
Have fun...
'Doc

I am trying to build this to work sats, ISS packet, mostly.

I've already got a good 5/8th wave on the back end of the truck for normal
use, I want this jobber for when I feel the need for spaceborne stations.