Severns' article "Verticals, Ground Systems and Some History",
July 2000, p. 39, quotes the following: "As indicated in Figure 1,
the tangential component of the H field (H(phi)) induces
horizontal currents (Ih) flowing radially and the normal
component of the E field (Ez) induces vertically flowing
currents (Iv). The paper is available for download
from www.arrl.org.

Frank

"Roy Lewallen" wrote in message
...
Richard,

I disagree with your conclusion that currents flow circumferentially. It
does not say so in the paper, and I don't believe it can be inferred from
what is said in the paper. If you were to draw a diagram showing the
currents produced by the phase shift between earth and radial currents,
you'd find that the net current resulting from this phase shift is purely
radial, not circumferential.

If the currents flow circumferentially, do they flow clockwise or
counterclockwise, and at what magnitude relative to the radial currents?
Surely there's some reference which shows this calculation which you could
direct me to or, if not, you could show how the calculation is done and
what the result is.

Roy Lewallen, W7EL

Richard Clark wrote:
On Mon, 09 Apr 2007 09:08:09 -0700, Roy Lewallen
wrote:

Richard Clark wrote:
On Sun, 08 Apr 2007 23:56:37 -0700, Roy Lewallen
wrote:

Indeed it is. Can you point me to a reference where I can get a more
detailed explanation of this circumferential current and its cause?
Hi Roy,

Brown, Lewis and Epstein.

Which page?

Hi Roy,

It is distributed through the discussion.

Pg. 757 (at the top of the page introduces):
"These losses are due to conduction of earth
currents through a high resistance earth..."

"Where there are radial ground wires present,
the earth current consists of two components,
part of which flows in the earth itself and
the remainder of which flows in the buried wires."

"...all the various components differ in phase."

This establishes the relationship and distinction in the various
currents. It is the current in the earth that is the topic of
discussion here. That current is out of phase with respect to the
currents (at the same radial distance) found in the buried wires. No
wires, no phase issue. No phase issue, and earth currents would be
radial. Now, to distinguish this from circumferential is not to say
this is absolute (it does not follow an arc of constant radius). This is
extended to coverage at the bottom of page 758:
"The actual earth current and the current flowing in the
radial wires are given...." [formula shown in the original]

"From (8) [that formula] we see that the earth
current proper leads the current in the wires
by 90 electrical degrees."

At a radius, the earth phase and the wire phase exhibit a potential
difference which results in conduction that is not strictly radial
(the term circumferential through the combination of vectors might be
replaced with spiral, or diagonal). The earth's resistance comes into
play at page 760:
"When the earth is of good conductivity [a paradox ensues],
the current leaves the wires and enters the earth closer to
the antenna than it does when the earth is a poor conductor."
and hence the advice for replacing dirt with sand OR providing more
closely spaced radials, closer in.

"Thus the regions of high current density are subjected
to still more current with higher losses in these regions."

73's
Richard Clark, KB7QHC