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February 4th 04, 01:17 AM

(Tom Bruhns) wrote in message om...

Then it's a bit of a puzzle. With two 4 cm pieces of wire connecting
a 50 ohm resistor to your meter, I wouldn't expect 2:1 SWR at 30MHz.
Maybe I can find time to try it on a good network analyzer today and
see what it looks like.

Did that. With two 100 ohm 1% 0805 SMT resistors in parallel right at
an SMA jack, using a freshly calibrated network analyzer at 30MHz, I
got about 60dB return loss, or about 1.002:1 SWR. Putting the same
two resistors on a pair of 4cm long 28AWG wires formed into a circular
loop, I got 17.3dB return loss at 81 degrees, which is about 1.32:1
SWR and matches up really well with about 73nH of series inductance
plus a tiny bit of excess series resistance. That's just about the
inductance my calculator tells me it ought to be.

So...I'd look for some other reason for the 2:1 SWR reading.

Cheers,
Tom