Measure Inductor Q factor at low frequency

[SK245230]

For measuring the Q factor of RF Inductors at High Freguency, I know we should use a network analyzer and measure S parameters. However, I need to measure the Q factor of an Inductor at low frequency (100KHz to 1MHz). Do I use also a network analyzer or is there any other device? Is network analysis the only way to measure the quality factor of Inductors?

 

[KlausST]

Hi,

Measuring voltage waveform and current waveform and calculate the phase shift should also give information of Q.

Or try to use something like a lock_in_amplifier, where it should be able to get phase information too. Check on this.

Klaus

 

[FvM]

A LCR meter can measure it.

 

[SK245230]

Ok thank you. I think I've got it.

If we measure the phase, we get tan(phi)=Lw/R=Q. Where L is the inductance, w is the pulsation and R is the resistance of the wire. So we can get the Q factor by measuring the phase.

 

[chuckey]

Be aware of the self capacitance of the inductor, it can give misleading results. In a RF Q meter, your U is a known current delivered through a very low value resistor (.04 ohms). In series with the earthy end of the L there would be a variable capacitor with a high impedance volt meter across it. So you energise it at a known frequency, and measure the capacitance and the voltage at the peak tuning point. Q = Vout/.04 X Iin. Or you can set the tuning cap to a given value then swing the frequency for a peak. If either measurement is repeated at two different frequencies the self capacitance of the inductor can be calculated.
Frank