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Measuring DCR of an inductor using VNA

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Full Member level 4
Apr 1, 2007
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Hi ,
i was thinking how to measure the DCR value for an inductor using a NA
The inductor is of interest is 56nH Midispiring air core type 1812MS56NL.
I just want to verify the value mentioned in the datasheet.
But datasheet says,
DCR tested on the Cambridge Technology Model 510 Micro-ohmmeter

DCR for 1812MS56NL is listed as 6.2mOhm, n they have mentioned 150MHz as the testing frequency (but i dont know whether it has got significance in DCR).

I connected the inductor to a VNA and did measurements in R+jXL mode.

What i got is

Z=5.38Ohm,R=11.46Ohm & L=60.9nH readings from the VNA.

Can somebody help?

Your measurement isn't related to DCR anyhow. What are exactly you asking for?

The reported results have been apparently confused, because L = 60.9 nH refers to an X rather than R value of 11.5 ohm. Series Z will be necessarily larger than this value.

According to the datasheet, Q is about 70 at 30 MHz, respectively Rser about 0.150 ohm. So you see, that it's considerably different from DCR. Skin effect is one obvious reason, but there may be other loss mechanisms.

Or in a short:
- DCR can't be measured with a VNA, because it's an AC instrument.


    Points: 2
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If you want to measure 'Real' DCR, you should use Multimeter, and you should use 4Wires measuring.
Resistance under 1ohm is difficult to measure with 2Wires.
4Wires measureing can reduce effects of contact resistance.

How will you measure DC Resistance with VNA ????
VNAs have lowest frequency limits that's why you can not meausre DC resistance of anything with VNA..
Find a precise milliohmmeter and measure it...that's it..

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