search

NanoVNA-Saver / nanovna-saver

A tool for reading, displaying and saving data from the NanoVNA
GNU General Public License v3.0
896 stars 273 forks source link

Q Information #60

Closed PY3IG closed 5 years ago

PY3IG commented 5 years ago

I would like to better understand the information from "Q" (This is a doubt and perhaps not a mistake). I noticed that the value of Q varies a lot as the markers show. In particular marker 4 has the value Q = 2.136 In another VNA I have Q = 84 for the same frequency. Using the same LC for testing. Please help me understand this difference. Thank you and congratulations for the beautiful work! Leituas Q IMG-20170822-WA0130 IMG-20170822-WA0132

PY3IG commented 5 years ago

In the news of 0.1.4 I found "quality factor S11". That is the difference of values "Q".

PY3IG commented 5 years ago

I found an explanation and it exactly matches the reading of the other VNA.

"You shod devide the imaginary part of Z21 to the real part of Z(21)" "There is old and good practical method. Simulate resonance circuit with your inductor and high Q (at least 10 times higher than expected inductor Q value) capacitor. Plot the S21 and measure 3 dB bandwidth. Then ratio of central frequency to this ratio will give you real loaded Q value of resonant circuit."

https://www.edaboard.com/showthread.php?127202-Calculation-of-Q-factor

Thanks!!

mihtjel commented 5 years ago

You're welcome, I didn't even have time to respond before you solved it :-) I hope you still find the software useful!

-- Rune / 5Q5R

On Wed, 23 Oct 2019 at 16:33, PY3IG notifications@github.com wrote:

I found an explanation and it exactly matches the reading of the other VNA.

"You shod devide the imaginary part of Z21 to the real part of Z(21)" "There is old and good practical method. Simulate resonance circuit with your inductor and high Q (at least 10 times higher than expected inductor Q value) capacitor. Plot the S21 and measure 3 dB bandwidth. Then ratio of central frequency to this ratio will give you real loaded Q value of resonant circuit."

https://www.edaboard.com/showthread.php?127202-Calculation-of-Q-factor

Thanks!!

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/mihtjel/nanovna-saver/issues/60?email_source=notifications&email_token=AGLTTOL3353BMPSHB6VTMQTQQBOELA5CNFSM4JEAS3YKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOECBUILQ#issuecomment-545473582, or unsubscribe https://github.com/notifications/unsubscribe-auth/AGLTTONOLOBYYRBJ6RCD72TQQBOELANCNFSM4JEAS3YA .

PY3IG commented 5 years ago

Very useful. User contributions and their excellent work will improve every day.