I just did exactly that. I modeled a simple 80m vertical with one
elevated radial 10 feet above ground ... 65 feet of vertical wire, 65
feet of elevated radial. The resonant frequency was 3.65 MHz and the
feedpoint impedance was 16 ohms real.
EZNEC+ gives the following results for max gain at 25 degrees elevation:
* zero wire loss .... 1.4 dBi
* 18 gauge copper wire .... 0.3 dBi
* 18 gauge Copperweld .... -0.25 dBi (note the minus sign)
* 20 gauge copper wire .... 0.04 dBi
So the difference between N2TK's 20 gauge copper and 18 gauge Copperweld
is just under 0.3 dB, which I consider to be essentially negligible ...
and I suspect that N2TK's setup has a higher feedpoint resistance than
the 16 ohms I modeled, which would make the impact even less.
73,
Dave AB7E
On 1/3/2020 7:36 AM, Wes wrote:
This can be modeled in EZNEC to remove some of the assumptions. A/B
test with copper then steel for the material.
Wes N7WS
On 1/3/2020 6:36 AM, jimlux wrote:
On 1/2/20 11:28 PM, David Gilbert wrote:
I'm using #18 solid Copperweld wire from Davis RF for my 160m
Inverted-L antenna. It tarnished quickly to a dark brown and is
virtually invisible. I'm not even sure I could spot it up in the
air if it didn't have some dacron line holding it up to tell me
where it is. The DC resistance is negligible ... something like
0.05 ohms per meter, I think.
A 40 meter length at 0.05 ohm/meter is 2 ohms. On a vertical (which
is what an inverted L is), with feedpoint impedance of 35 ohms, 2
ohms is about 6%, or a 0.3 dB loss? (huge assumptions here about
uniform current distribution, AC resistance = DC resistance, etc.)
It's amazingly strong, too.
73,
Dave AB7E
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