Longitudinal Wave Experiment

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>

Hi Ed,

>> There is no doubt at all that longitudinal waves exist on the ground
plane.
>> I would venture further and say that radio waves cannot be detected along
>> the ground (or at least they will be severely diminished.)
>  Not sure what you mean by that, but ground wave transmission is the
normal mode for ALL commercial BC stations.

I'm talking about the ground plane, not the ground.  The ground plane for a
quarter wave antenna is the surface between the earth and the atmosphere,
not the earth below the surface.  By definition, the ground plane is zero
volts wrt a resonant quarter wave antenna.

>> How many HAM operators do you see trying to receive HF with antennas
lying on the ground?
>  A number of people have used them quite successfully.  It's easy,
particularly where the soil conductivity is as low as it is in most places
on land.

This isn't the same thing.  Lying an antenna on the ground is different from
burying an antenna or sinking a ground rod.  When I say "lying an antenna on
the ground," I mean literally lying the wire right on the surface of the
earth.  No ground rods, no aerials, nothing is buried.  The wire is flat on
the ground.

I've put this experiment to a friend of mine.  We're going to get two 20
foot lengths of 4.5" OD plastic pipe and tape two 40 foot long wires to the
pipe 4.25" apart.  In the middle of these wires we will use the half wave of
a nearby 1390KHz radio transmitter that happens to be in the line of site
from my yard.  The long pipes will lie directly on the ground and we will be
able to turn them to test for angular alignment with the radio station.

A crystal radio will be placed across the two wires in one test to see if
there is demodulation.  Then the pipes will be lifted as high as possible to
see if there is a change in performance.  I'll also measure voltage at the
ground level and at a higher level.  We will also conduct these measurements
with the pipes rotated in different angles wrt to the transmitter.

I will also cut three metal pipes.  One will be 3 times the wavelength of
the half wave, one will be three times the length of the full wave, and one
three times the length of pipe where the nodes are spaced equal to the half
wave of 1390KHz.  If there is a longitudinal component to this wire
arrangement, it will cause these pipes to mechanically resonate.

The purpose of this experiment will be to see if there are any clear
indications that longitudinal waves are present.

Dave