On 6/23/23 6:51 AM, Garry wrote:
The different measurement techniques usually arise due to the propagation of error. In the case of vna's the measurement methods relate to the impedance of the DUT. You will find a number of articles online describing how to mak accurate measurements. One such article is
Basically, a 1-port measurement works best around the 50 ohm port impedance, shunt-through works best for low impedance, and series-through works best for higher impedance.
I believe the original question was more about "how do I figure out which mix this unmarked toroid is" and for that, measurement accuracy may not be super important, especially if you have some known examples to compare to.
The nice thing about a VNA is you can easily sweep a wide frequency range, so you're looking for a "does my curve look more like curve A or curve B", rather than a single spot measurement at a single frequency and trying to figure out if your estimate of mu is correct.
The what do R and X look like vs frequency is a pretty good way to distinguish materials. And if there's a measurement error it might not perturb that much. What you're really looking for is "not lossy at frequency range X but lossy at frequency range Y"
