# How to calculate line impedance?

#### kodolsinteze

Joined Oct 15, 2015
2
Hello!
I have a problem with finding out the impedance of a line.
Im working on a project and i need to find out a way how to calculate(find out) the impedance of a given line not using time domain reflectometry.
What measurements i have to do to find out the impedance using only frequency domain?
The frequency range is from 100khz-2Ghz.
Im out of ideas, any smarter people out there?

#### Domophone

Joined Sep 10, 2013
65
calculate(find out) the impedance of a given line
I think you need to provide a little more detail so people can help you. Are you calculating co-ax characteristic impedance, or a more generalized transmission line?

#### kodolsinteze

Joined Oct 15, 2015
2
Oh, it's a microstrip.

#### alfacliff

Joined Dec 13, 2013
2,458
you use the dielectric constant of the substrate the wwidth, thickness and spacing of the conductors, and the strip line impedance formula.

#### Domophone

Joined Sep 10, 2013
65
Oh, it's a microstrip.
A microstrip will have a pretty constant characteristic impedance over the frequency range you specified (less than 1% variation), just use one of many calculators online as a quick solution.