Re: NEC-LIST: Ground Constants at 1.161 kHz for "Good" Ground

Paul:

Thanks for pointing out that I had a typo in my email regarding
frequency. It was indeed 1.161 MHz and NOT kHz.

There is a good explanation in the book, ANTENNAS IN MATTER, by
R.W.P. King and G. Smith about why the epsilon r can rise so high for
soils with moisture content. The 80 or 81 is for water by itsely, but
when the water is attached to a soil particle, and tries to orient
itself in the E field imposed, the water molecule has to try to drag
the soil particle along into that alingment, and the result is an
effective epsilon r much greater than the water or soil alone. This is
explained in far better form in the book mentioned above.

I actually tested the theory that epsilon r could be greater than one
in Thailand years ago, by mneasuring the E field vs distance across a
rice paddy from an HF transmitter. I needed the high epsilon r to
match the measured data, essentially the same high value I had
measured with my open-wire line (OWL) probe in the same rice paddy. So
I became a believer in large effective epsilon r values at the lower
frequencies for moist soils.

All for now.

George
Received on Mon Aug 02 1999 - 17:31:36 EDT