REPEAT

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

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Don't think this got through the first time.

> 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.  They use vertical antennas
to maximize the signals. If the soil conductivity is very high
horizontally polarized signals have a null in the ground plane,
regardless of their elevation.  Ground wave propagation OF EM RADIATION
was first recognized in the very early 1900's, not long after Marconi's
original transmissions.  Zenneck published a good explanation about this
back in
1906, and the subject is treated quite well in the 1915 English
translation of his which I have.  Almost certainly was in the earlier
German editions too.  There's been no real revision of things since
then, except for better mapping of ground conductivity.  Technique is
still used for siting of BC antennas and predicting signal strength
contours, as well as predicting performance at higher frequencies.

 > 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.  Plenty of data
on the geographical distribution of ground conductivity in any radio
handbook, as it's a key parameter in determing performance of line of
sight systems, whether they be TV or FM signals subject from which
direct and ground-reflected waves arrive at (nearly) the same time, or
ground wave BC signals.  High conductivity is always best for the
latter, but not necessarily for the former.  A long single wire laid
out in a straight line (on the desert, not salt water) is an excellent
VLF receiving antenna and can be effective well up into the HF region.

        On the general topic of ground conductivity, Tesla never
considered it
as much as he should have.  Remember that he was talking about "wireless
transmission", NOT CONDUCTORLESS TRANSMISSION.  His patents state quite
clearly that he planned to use the ionized upper atmosphere as one
conducting path of the transmission line and the earth for the other.

Ed