Can this be used to check antenna resonance?

MikeN ZL1BNB


On Wed, 10 Sep 2003 03:38:12 GMT, "Rick Karlquist N6RK"
wrote:

You don't even need a bridge. Just put a BNC "tee" in line between
any signal generator and any detector. Now put your LC series
resonant tank on the third port of the tee. At resonance, the LC
will suck out the signal and you will see a dip in the response.
This method is more accurate than the bridge method you describe.

Regarding small inductances: the capacitor has to have negligible
inductance compared to the inductor you want to measure.

Rick Karlquist N6RK


"Richard Hosking" wrote in message
.au...
My Friend Rod VK6KRG uses a snazzy method of calculating inductance using
a
return loss bridge
I have tried it to measure a 500nH inductance and the result agrees
closely
with the calculated result for an inductor of that physical size and
number
of turns.

Basically he uses the unknown inductor, in series with a known capacitor,
in
series with a 50 ohm load across the "unknown" arm of the bridge. When
XC=XL, then the two reactances cancel (assuming they approximate to an
ideal
reactance) and load presented to the bridge by the RLC circuit = 50 ohms.
Thus you tune the system to best return loss which is a null and calculate
XL at this frequency You can even do this at the end of a section of 50
ohm
coax, assuming the loss isnt too great

No doubt all you RF experts out there have known about this for a long
time - has it been published as an idea before?

Richard