[TowerTalk] 80M antenna wire size

[David Gilbert]

Both diameters are really, really small relative to a wavelength at 
80m.  After a point the effect of the differences isn't a big deal.

The model is really simple ... just one straight wire fed in the 
middle.  If you trust EZNEC+ at all it's pretty difficult to mistrust 
that model.

No, I can't explain why you saw an improvement in bandwidth with 10 
gauge wire on your 80m Inverted-V, but I'd be interested in what "much 
wider" actually was if you still have the figures available. One thing 
that does scale fairly linearly with diameter is capacitive coupling to 
surroundings.  Possibly (just speculating here) there was some resulting 
loading effect from that for your antenna.

73,
Dave   AB7E



On 1/5/2020 10:57 AM, Jim Thomson wrote:
> Date: Sat, 4 Jan 2020 14:37:10 -0700
> From: David Gilbert <xdavid at cis-broadband.com>
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] 80M antenna wire size
>
>
> <According to EZNEC+, an 80m dipole at 100 feet (resonant and matched at
> <3.7 MHz) has a 2:1 SWR bandwidth from 3.55 MHz to 3.87 MHz with #10
> <copper wire and from 3.57 MHz to 3.86 MHz with #18 copper wire. Much
> <thicker conductors or similar conductors at higher frequencies would
> <make more difference of course (I've modeled 12 inch diameter wire cages
> <for 80m and they make a usable improvement in bandwidth), but in spite
> <of what somebody just posted the advantage for #10 wire on 80m does not
> <seem significant to me for bandwidth.
>
> <Dave?? AB7E
>
> ##  10  gauge  wire  is  .102  inches  in  diameter.
>        18  gauge  wire  is .0403  inches  in  diameter.
>
> ##  .102 / .0403  =   2.531
>
> ##  10  gauge is  2.531  x  the  circumference  of  18  gauge  wire.   Thats a bunch.
> Thats a huge  difference  in  Length  to  diameter  ratio.
>
> ##  I  have  never  tried a    80m  wire dipole  at  100  ft,  but  have
> used  a  full  sized  wire  inverted  vee  on  80m.
>
> ##   10  gauge  wire  provided  for a   much wider  BW,  vs  the   16  +18  gauge  I  tried  previously.
> 2  other  folks here  in  town tried the  same experiment...with  same  results.   Again,  inverted  vee  used.
> Is  EZNEC modeling    your  dipole  correctly ?
>
> Jim  VE7RF
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk