Reg Edwards wrote:
"Owen" wrote

Reg, I mentioned in an earlier post that I was concerned about the
estimate of the loop inductance.


Owen,

The HF inductance of a square loop is -

L = 0.8 * H * ( Ln( 4 * H / D ) - 1.467 ) microhenries,

where H is length of one side,

and D is diameter of circular conductor,

both dimensions are in metres.


Though it looks a little different, that formula will always produce
exactly the same results as the one that I have used.

There are half a dozen other formulas which at first appear to be
different from the above but can be mathematically transformed to be
identical. And then there are imperial and metric units.

I got it out of one of one of my old notebooks. It's what I use in my
programs. I think I stole it from Terman. And Terman stole it from
Grover. So it's sure to be accurate enough for anything you are ever
likely to use it for.

I looked in Terman, but didn't find it, and still can't. I might be blind!

I got it from http://emcsun.ece.umr.edu/new-induct/ but it obviously
shares the same root as yours. They attribute it to Grover.


It is obviously an approximation because when a large conductor
diameter is comparable with a very short length of side, the
inductance has a negative value.

Understood.


As a sanity check, compare it with whatever formula you have used up
to now.

See above. I think you are telling me I should be confident I am sane.
If it was just that easy!

Now I just have to find someone with access to an OATS to measure one of
these things.

Thanks Reg...

Owen