Re: transmission line z

On Sun, 8 Jun 2025 20:43:31 +0200, Leo Baumann <ib@leobaumann.de>
wrote:

Am 08.06.2025 um 16:58 schrieb john larkin:

Suppose you have a slab of FR4 with copper on both sides, standard
ebay stuff. Now shear off a long thin slice. That's a balanced
transmission line.
 
air
__________________ copper
.........................................fr4
__________________ copper
 
air
 
 
 
What's that called?
 
Does anyone know of a calculator that handles this case?
 

https://saturnpcb.com/saturn-pcb-toolkit/

I use Saturn all the time, but it doesn't seem to have that case.

I can TDR a strip of copperclad and iterate, or scale it, and get
close enough. The transmission lines in a txline transformer don't
really, or usually, match the system impedance.