transmission line z

You have ATLC, no?

Jeroen Belleman

Neither of my transmission line textbooks say anything about that. It's clearly a kind of transmission line, but presumably not a useful one - it's going to be dispersive, just like microstrip. If it was useful you would presumably be able to buy reels of it.

Used that way it's called a "parallel plate line" and the essential characteristics for ye olde Telegrapher's Equation are given in Pozar:

Except that between the plates is FR4, dielectric constant near 4.

I could test that case experimentally, TDR some strips of copperclad.

Another case that I'm interested is a 5-layer board where the parallel conductors are on layers 2 and 4.

air .........................................fr4 __________________ copper .........................................fr4 __________________ copper .........................................fr4 air

Or even

air .........................................fr4 __________________ copper .........................................fr4 __________________ copper air

Yes, I guess I'll have to crank up ATLC, which is rather a nuisance to drive.

The goal is to build some high-voltage transmission-line transformers using pot cores with stacked layers of PCBs as the windings, sort of like the Coilcraft planar transformers.

PCBs with odd numbers of layers are, well, odd.

Am 08.06.2025 um 16:58 schrieb john larkin:

It's okay, in those equations epsilon prime is defined as e_r*e_0, and then epsilon double prime is related to the loss tangent of the dielectric is related as tan(delta) = (omega*e'' + sigma)/omega*e'

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.

But all the capacitance is assumed to be confined into the central rectangle, with the rest of the universe having e=0.

That's maybe good enough if the dielectric constant of the stuff between the plates is high, and the w/t ratio is large. But it ain't right.

Am 08.06.2025 um 21:29 schrieb john larkin:

in German language, but the formulars are clear ...

This message was cancelled from within Mozilla Thunderbird

Am 08.06.2025 um 21:29 schrieb john larkin:

Am 08.06.2025 um 21:29 schrieb john larkin:

The formulars are for 2 symmetrically lines in picture 4.20.1-3 on the

... have fun ...

Double-strip transmission line or dual stripline.

Joe

And broadside coupled stripline.

Joe

Please take another picture of the second page.

Thanks,

Joe

Am 08.06.2025 um 22:37 schrieb Joe Gwinn:

In germany we have no name - We call it symmetrically stripline without groundplane

Am 08.06.2025 um 22:42 schrieb Joe Gwinn:

sorry - it is a very thick book, I cannot do it better with my A4-scanner

Am 08.06.2025 um 22:42 schrieb Joe Gwinn:

please, scroll down the *.pdf

Simple solutions are for simple problems, and all that...

If the frequency is high enough you can use that structure as a waveguide, too! It supports TE, TM, and TEM, though some modes may be more appropriate than others, depending