[TowerTalk] 80M antenna wire size

David Gilbert xdavid at cis-broadband.com
Fri Jan 3 12:15:21 EST 2020


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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