[TowerTalk] Force 12 C31XR Modeling

[Lux, Jim]

On 2/22/23 9:32 AM, David Needham wrote:
> Anyone's guess on the transmission line impedance as described? I've found
> calculators for 2 conductors in free space, but I'm scratching my head on
> what the Romex covering will do for the dielectric constant. So far my 120
> ohms seems like a decent guess, but I wouldn't mind having something better
> than my guess.

I'd try an epsilon of 2.  Most plastics are around 3 (depending on water 
content), but there's some air space too.

Twisted pair with PVC or PTFE insulation has a Z0 of about 100-120 ohms -

You could measure it if you were ambitious.  It's a short piece, isn't 
it? Way less than a wavelength? it might not make much difference.