RadioBanter - View Single Post

[email protected] · November 30th 15, 06:34 PM posted to uk.radio.amateur,rec.radio.amateur.antenna

In rec.radio.amateur.antenna Spike wrote:
On 29/11/2015 23:24, wrote:

OK, I added radials for a total of 5 in a 45 degree spread and optimized
for minimum reactance.

radiator: 203 inches, radial: 186 inches, R: 52.4 Ohms, X: 0.4 Ohms

SWR: 1.1, Maximum gain: -.18 dBi in the direction of the radial and an elevation
angle of 30 degrees, Reverse gain: -3.7 dBi

Note with one radial the F/B ratio is about 5 dB and with five radials
it is about 3dB.

About the only thing I can see worth noting about this antenna is that
it shows more radials are better, but everyone already knows that.

Imagine a case whereby someone digs up the soil around the base of a
vertical antenna, a couple of feet deep and as far out as the antenna is
tall. Into this they mix 2 percent of high-aspect-ratio thin conducting
fibres, say about a foot long, and then replace the soil. 2 percent of
conducting fibres in an essentially non-conducting medium is about the
minimum proportion necessary to reach the percolation threshold..

What results from your modelling exercise do you get in this case?

Modeling thing buried in the soil requires professional software that
costs on the order of $1,000.

To do this with reasonably priced (for a hobby) software requires that
effective soil conductivity be determined.

Send me either $1,000.00 or the effective soil conductivity and I'll
be glad to do it.

--
Jim Pennino