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#1
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On Mon, 09 Apr 2007 13:27:21 -0700, Roy Lewallen
wrote: So, does the current go clockwise or counterclockwise? How much goes that way compared to the radial component? Where can I find a quantitative or explicit statement of your interpretation? Hi Roy, Probably in a library. Field work seems to resolve issues too. It may even prove your speculation in contradiction to mine. Outside of these authors, we both seem to be shy of "authoritative references" to parse that Byzantine statement of theirs. I can only further speculate that BL&H were remiss in specifically quantifying loss (you aren't asking me for numbers you are already aware of, are you?), while offering numerous formulaic relationships of loss against many factors. If we look at their data and observe that adding radials lowers loss, but not by any precise relationship, are we left without quantifiable proof, or the obvious implication of strong correlation? Was there deceit in their arriving at some conclusions through inference? As Reggie would note, they didn't actually measure earth at all! Such a retort was met with indignity in the past, is it now their impeachment? However, as to counter/anti/clockwise, What impels current to follow any such presumption? There are two sides to every wire laying in a plane and phase mappings for earth currents that are symmetrical about them. To anticipate your challenging me on that statement (clearly BL&H never, explicitly say this), I can only offer a modest sense of observing the bleeding obvious. Myself, I don't find BL&H so obscure to impose this remarkable characteristic that current leaves the wire on only one side. Brown, Lewis and Epstein were REPORTING, not inventing, nor offering pedant readings of scripture. Scribes, such as we are, are free to interpret within the bounds of their own data, assumptions, and conclusions. I've offered mine that conforms to many of their points. If you have your own, you must survive by the same strictures. Given the specific contention, I am especially intrigued in how you would answer why the current departed the wire, and where it goes in light of a potential map created by the phase shifts. 73's Richard Clark, KB7QHC |
#2
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Richard Clark wrote:
On Mon, 09 Apr 2007 13:27:21 -0700, Roy Lewallen wrote: So, does the current go clockwise or counterclockwise? How much goes that way compared to the radial component? Where can I find a quantitative or explicit statement of your interpretation? Hi Roy, Probably in a library. Field work seems to resolve issues too. It may even prove your speculation in contradiction to mine. Outside of these authors, we both seem to be shy of "authoritative references" to parse that Byzantine statement of theirs. I can only further speculate that BL&H were remiss in specifically quantifying loss (you aren't asking me for numbers you are already aware of, are you?), while offering numerous formulaic relationships of loss against many factors. If we look at their data and observe that adding radials lowers loss, but not by any precise relationship, are we left without quantifiable proof, or the obvious implication of strong correlation? Was there deceit in their arriving at some conclusions through inference? As Reggie would note, they didn't actually measure earth at all! Such a retort was met with indignity in the past, is it now their impeachment? However, as to counter/anti/clockwise, What impels current to follow any such presumption? There are two sides to every wire laying in a plane and phase mappings for earth currents that are symmetrical about them. To anticipate your challenging me on that statement (clearly BL&H never, explicitly say this), I can only offer a modest sense of observing the bleeding obvious. Myself, I don't find BL&H so obscure to impose this remarkable characteristic that current leaves the wire on only one side. Brown, Lewis and Epstein were REPORTING, not inventing, nor offering pedant readings of scripture. Scribes, such as we are, are free to interpret within the bounds of their own data, assumptions, and conclusions. I've offered mine that conforms to many of their points. If you have your own, you must survive by the same strictures. Given the specific contention, I am especially intrigued in how you would answer why the current departed the wire, and where it goes in light of a potential map created by the phase shifts. 73's Richard Clark, KB7QHC Ok, I understand that. Your answers to the two questions I asked are that you don't know and you don't know. In the absence of any evidence, I'll continue to disbelieve there's a circumferential component of the current. Roy Lewallen, W7EL |
#3
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On Mon, 09 Apr 2007 16:42:10 -0700, Roy Lewallen wrote:
Brown, Lewis and Epstein were REPORTING, not inventing, nor offering pedant readings of scripture. Scribes, such as we are, are free to interpret within the bounds of their own data, assumptions, and conclusions. I've offered mine that conforms to many of their points. If you have your own, you must survive by the same strictures. Given the specific contention, I am especially intrigued in how you would answer why the current departed the wire, and where it goes in light of a potential map created by the phase shifts. 73's Richard Clark, KB7QHC Ok, I understand that. Your answers to the two questions I asked are that you don't know and you don't know. In the absence of any evidence, I'll continue to disbelieve there's a circumferential component of the current. Roy Lewallen, W7EL Roy, it seems to me everyone has missed an important point concerning a circumferential component of the current. We know that the current flowing on the radial wires is radial in direction. What seems to be missed is the current that returns to earth between the wire radials. That current is going to flow in the direction of the lowest resistance. As such it's not going to flow radially alongside the currents flowing on the wire, because the radial resistance of earth between the radial wires is much greater than the resistance of the wires. Consequently, currents reaching earth between the wires will find a lower resistance by traveling toward the nearest radial wire instead of continuing in a perfectly radial direction. This new direction of current flow will not necessarily perfectly circumferential, but will certainly be somewhere between radial and circumferential. Walt, W2DU |
#4
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On Thu, 12 Apr 2007 18:55:30 GMT, Walter Maxwell
wrote: This new direction of current flow will not necessarily perfectly circumferential, but will certainly be somewhere between radial and circumferential. Hi Walt, So as BL&H report without too much pain: at page 760: "When the earth is of good conductivity, the current leaves the wires and enters the earth closer to the antenna than it does when the earth is a poor conductor." Now, as to your comment That current is going to flow in the direction of the lowest resistance. It is awfully damned hard to beat the least resistance path of copper over earth. And yet BL&H offer us this observation I requote above. What will trump a higher resistance path is greater potential difference and proximity. Note that BL&H are quite specific about proximity to the antenna, and hence it follows that the separation between radials is closer there, than further out from the antenna. Certainly I can find no where to quote this observation of growing closeness from BL&H for Roy's consideration, but I trust my common sense of geometry here too, and I will proceed. BL&H report (without going into the how, or how much): "From (8) [that formula] we see that the earth current proper leads the current in the wires by 90 electrical degrees." such that at "that" radial distance, there must exist the greatest circumferential potential difference between the wire and the earth currents which is clearly mandated by phase. If a potential gradient along the circumference is greater than that along the radial, and the distance along the circumference is smaller than the distance along the radial; then it stands to reason why BL&H even offer to comment "current leaves the wire." Current through earth is largely lost to heat although I do have a fractal antenna that uses earth current to optimize its low angle launch characteristics. Ultimately this reduces to the rather pedestrian observation that more radials closer in serve efficiency - observed and reported by BL&H. 73's Richard Clark, KB7QHC |
#5
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Walter Maxwell wrote:
Roy, it seems to me everyone has missed an important point concerning a circumferential component of the current. We know that the current flowing on the radial wires is radial in direction. What seems to be missed is the current that returns to earth between the wire radials. That current is going to flow in the direction of the lowest resistance. As such it's not going to flow radially alongside the currents flowing on the wire, because the radial resistance of earth between the radial wires is much greater than the resistance of the wires. Consequently, currents reaching earth between the wires will find a lower resistance by traveling toward the nearest radial wire instead of continuing in a perfectly radial direction. This new direction of current flow will not necessarily perfectly circumferential, but will certainly be somewhere between radial and circumferential. Walt, I hadn't missed that phenomenon, but didn't mention it because it doesn't produce a circumferential current. If you look at the current flowing from the earth to each radial wire, you'll see that the sum of these currents will be purely radial, assuming that the system is symmetrical, i.e., radials are equally spaced and equal length, the ground is homogeneous, and the radiator is vertical. Consider a bit of current returning between two radials, which is a little closer to the radial on the right. It'll detour to the right, giving it a rightward component as well as an inward radial component. But for every such bit of current, there's another one the same distance from the radial to the left which will have leftward and inward radial components. The radial components are in the same direction (inward) so will add but the circumferential ones (leftward and rightward) cancel, leaving a net radial current flow. You can say that the returning currents bend to the right or left as they propagate toward the antenna base, but not that there's a systematic circumferential current flow -- no current crosses from radial to radial in a clockwise or counterclockwise circular pattern like Richard implied. I recall reading a paper which showed that connecting radials with circumferential wires actually degrades a ground system's effectiveness, but I wasn't able to lay my hand on it when I looked. Roy Lewallen, W7EL |
#6
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On Thu, 12 Apr 2007 13:53:30 -0700, Roy Lewallen
wrote: no current crosses from radial to radial in a clockwise or counterclockwise circular pattern like Richard implied. Hi Roy, This, like: Your answers to the two questions I asked are that you don't know and you don't know. inject your meaning into this dialog as though I wrote it. I wrote neither that I didn't know (this is strictly your interpretation) nor have I implied radial to radial conduction. Please review the correspondence and respond directly to my comments as written instead of creating my talking points for me. This is Cecil's style, not yours. 73's Richard Clark, KB7QHC |
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