Perhaps an example will make it clear.

Suppose you have a coil which measures 1 uH at 1 MHz. It is known to
have a self-resonant (parallel) frequency of 100 MHz.

You measure its reactance at 1 MHz using the formula X=2*pi*F and find
it to be 6.28 ohms.
At 2 MHz you find it to be 12.56 ohms.
At 10 MHz you find it to be 62.8 ohms.
So far the reactance is changing linearly with respect to frequency.
(Actually it is not perfectly linear, but the difference at these
frequencies is small and probably would not be observed with run of the
mill test equipment.)

But, as you approach 100 MHz, you find the change is obviously no longer
linear.
At 95 MHz you would expect the reactance to be 6.28*95=596.6 ohms, but
much to your surprise, it measures 1000 ohms.
At 99 MHz, instead of the expected 6.28*99=621.72 ohms, it measures
50,000 ohms!!

All the above is perfectly normal and easily observable.

My point is that when a coil measures 50,000 ohms at 99 MHz, its
inductance HAS TO BE L=X/(2*pi*F), or 50,000/(6.28*99)=80.4 uH!

This is not an illusion. If you have an inductance meter which uses 99
MHz as a test frequency, it WILL MEASURE 80.4 uH.

And therefore, I maintain that inductance DOES vary with frequency.

How can it be otherwise?

--
Bill, W6WRT

The inductance is not changing. What you are measuring is not pure
inductance but the coil has a stray capacitance. That is what is making the
coil seof resonate.

YOu did not say what hapens at 110 mhz, 200 mhz, and 500 mhz, if you did ,
it would measuer capacitance reactance. How do you change a coil into a
capacitor ? You don't , but the effect of reactance has.

Look at it this from a totally differant angle. You stick the leads of a DV
voltmeter in the wall socket. It does not show any deflection other than
maybe the first jump when it is plugged in. Does that mean there is no
voltage or power in the circuit, I think not. Stick your fingers in it and
see what hapens :-)

Your method is flawed in the same way, you only measured inductance ( not
really that , but the inductive reactance at a given frequency, but did not
measuer capcitance. Where did the capacitance come from ? It is what makes
the coil selfresonante. If you measuer a circuit that has inductance,
capacitance and resistance, depending on if it is series or pareallel
resonate here is what will hapen. As the frequency is increaced the
inductance reactance will increace, it will measuer resistance at the
reosnant frequency , then a large capacitance reactance and then a small
capacitance reactance or else the reverse will hapen, capacitive reactance,
resisstance, inductive reactance. However none of the actual inductance,
capacitance or resistance values will change. YOu are confusing inductacne
and reactance.

YOu are only seeing one part of the big picture. YOu have to look at
several formulars to see what is going on in a circuit that has inductance
and capacitance.