[Lowfer] Loop Antennas for Transmitting

[Bill Ashlock]

Ed,

> > I'm at a Q of about 200 with both the Litz cable and 1/2" cu pipe. > 
> >The soil loss at the moment is about .22 ohms and probably won't
> >improve.
>
>Roger and very interesting. How do you measure or figure the soil
>loss?

The Rac value I use for the pipe (not counting the soil loss) is close to 
.18 ohms per 200ft, as calculated from the std formulas that include skin 
effect loss. The measured Rac when installed at a ground clearance of 6ft is 
more like .40 ohms so what remains is the soil loss of .22 ohms. The .22 
ohms is constant between measured and calculated Rac for all the tested loop 
conductors up to #12 AWG. It turned out that the soil had to be real dry for 
making these measurements in order to avoid getting confusing results. 
Thoroughly damp soil has a loss of about .34 ohms and the effect on antenna 
current is large for the better conductors and only about 10% for #12.

Jay R. has very different soil under his loop but sees similar loss numbers. 
Mike's soil loss numbers in MN for his #12loop appear to be close to mine as 
well. I think the main difference between soil types in so far as their 
effect on the loop Rac is in the time it takes for the soil to dry out - 
sometimes weeks!

It doesn't appear that classic soil conductivity is the real variable, but 
whatever it is that causes this loss (soil permittivity as for a core 
material?), it mimics the conductivity for moisture effect. It's probably 
fortunate that we are all at 1w because we share more of a common desire to 
figure this out.

Bill

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