to measure nanohenry inductors - RF Cafe Forums

 Post subject: to measure nanohenry inductors

Posted: Wed Apr 02, 2008 6:15 am 

Hi!!

I have designed LNA for 1420MHz by tunning microstrip lengths and inductors in GENESYS.

These inductors are in nanohenry(values are:16,24,390,58) and made by wounding copper wire on former.

Can u suggest me a practical method to measure these inducors since i don't have any LCR or Qmeter in nanohenry range.It's really urgent.

Thanking you,

shari

 Post subject:

Posted: Mon Apr 14, 2008 11:11 am 

There are ways.
Do you have a signal generator, and maybe a scanning receiver covering VHF?
If you can arrange to create a series tuned circuit using accurate close % tolerance capacitors, then if you feed the generator into the series circuit across the series-connected L and C, a receiver connected across the circuit will produce a minimum signal as it is almost a short circuit across the 50 ohms.
Since you know the C value accurately and the L value approximately, this narrows the search range down to a few MHz on the receiver. Then when you know F very precisely, you can correct the L value using the well-known resonance formula.
Hope that helps.

 Post subject:

Posted: Wed May 14, 2008 3:08 pm 

Yes, a series LC circuit will provide you an easy way to meas the L. Just be careful to have a well known C (with low tolerance), place the L an the C as close as you can to each other, and be sure to place them into a line with the correct characteristic impedance.
And if you want to be more accurate, once you have a first approach to the L value, reselect the C in order to have the resonance infrequency around the frequency you will be using the L (1420MHz), remember that L value also is function of the frequency.

Good luck! (www.viewrd.com.ar)