[TowerTalk] solid THHN vs jacketed copperweld

[Jim Brown]

On 9/20/2022 10:10 AM, Grant Saviers wrote:
> The dielectric loading of insulation makes the wire electrically longer 
> for RF.  EZNEC can model it, if you know the dielectric constant 
> (usually around 3 for PVC, nylon) and thickness.
> 
> The height of the dipole has a larger effect.  Plus for 160 & 80 quality 
> copperweld is needed with thick copper, so the internal field (skin 
> depth) is in the copper, not in the steel which will cause high losses.

EZNEC can also model the effect of height if you know what your soil is 
like. It correctly predicted a good match to 75 ohm coax for an antenna 
at about 40 ft over lousy soil for a CQP setup we did, and it comes 
pretty close to measurements (~ 85 ohms) for my very high dipoles over 
lousy soil.

73, Jim K9YC