Re: Longitudinal Wave Experiment

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

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

Tesla list wrote:
> 
> 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.

	By measurement, its not zero volts.  I suggest measuring one.
	(Hint:  It is common, in some texts, to make simplifying
	assumptions...)
 
> >> 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.

	On the ground or in the pipe?

> 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 sight 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.

	This arrangement will detect conventional EM.
 
> 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.

	Amy good antenna text will discuss the influence of dipole
	height over ground.

> 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.

	cf above.  All done and documented, decades ago.

> I will also cut three metal pipes.  One will be 3 times the wavelength
> of the half wave,

	?
	3 times the half wave, or three times the wavelength?
	Errrrr.
	roughly, that's 375 meters of pipe, at 1390 KHz...
> one will be three times the length of the full wave,

	that's near a km of pipe...  

> 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.

	Which will be detected how?

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

	best
	dwp