# How to make proper copper trace transmission line calculations using wCalc?

Oli Glaser gave a fantastic answer to a question regarding termination resistors: Termination resistors: are they needed?

I am trying to replicate his wCalc and SPICE simulation calculations for learning purposes.

I've got about everything figured out except how exactly he came to his wCalc results.

Here is a screenshot at my failed attempt of coming to the same result as Oli did using wCalc.

Oli gets:

Zo = 177.6Ω
L = 642.9 pH/mm
C = 0.0465 pF/mm
R = 34.46 mΩ/mm
Delay = 530.4 ps


I get:

Zo = 117.6Ω (considerably off)
L = 642.8 pH/mm (only 0.1 ph/mm off)
C = 0.0465 pF/mm (same)
R = 9.072 mΩ/mm (considerably off)
Delay = 530.3 ps (only 0.1 ps off)


Since some numbers, L, C, and Delay are equivalent or off by just a fraction, but Zo and R are considerably off, I'm a bit perplexed.

I suspect it's a typo on Oli's part. When I put the parameters into the web-based calculator, my values match Oli's, except for the $Z_0$. You can see how 177 is a plausible typo for 117.