Rogowski Coil High Frequency Limit

Question

I'd like to do some experiments involving high frequency (1.296GHz to be exact) that involve an 50ohm inductor that has minimal RF losses. The obvious candidate is to drive a Rogowski coil (driven as though an air-core current transformer without a secondary running through the centerline) since it generates no external fields -- only a dynamic B-field within the minor radius of the torus.

The problem is when I look at the application of Rogowski coils to current sensing, the frequency limits seem to be a factor of 10 lower than my target.

What limits the frequency of a Rogowski coil to below the GHz range?

Answer 1

What limits the frequency of a Rogowski coil to below the GHz range?

Mainly the fact that it is by definition a multi-turn inductor, and the self-resonant frequency is going to be a few hundred MHz at best.

An inductor that has an impedance of 50Ω at 1.296 GHz has an inductance of 6.14 nH. That's a really tiny value, and it's really difficult to make a low-loss discrete inductor with that value. Another issue is that the skin depth for copper at that frequency is only about 2 microns. That's why most work at microwave frequencies is done with silver-plated tuned cavities and striplines.

What is it that you're really trying to accomplish? If you can be more specific, we can come up with more appropriate approaches for you to try.