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The article is in QST.
"Frank's" wrote in message news:6qxSh.56971$__3.40608@edtnps90... 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 |
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