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Loading Coils; was : Vincent antenna
On Fri, 14 Dec 2007 05:18:03 -0800, "Roger Sparks"
wrote: That IS what I said. Think of the velocity as a moving wall, with the capacitor charged behind the wall, uncharged in front of the moving wall. .... Be real. This experiment can be performed, and the DC switched as frequently as desired. How square the wave front will be depends upon real world factors. Go to a transmission line characteristics table and use the formula to compare Zo, capacity per length, and line velocity. It will amaze you. Hi Roger, Take a deep breath, exhale, give what's above some more thought in light of many objections. Now, tells us just what significance any of this has in relation to already well established line mechanics? It certainly isn't different within the confines of its limitations if that is what you are trying to impress upon the group. I suppose for a mental short-cut it has some appeal, we get too many theories here based on approximations to stricter math. One such example is when an equation of approximation has forgotten the underlying |absolute value| and suddenly an inventor arrives with a "new" theory that discovers uses for negative solutions. Further, there is nothing DC about it at all. DC is either static (and in spite of Arthur's corruption of the term, that means no movement whatever) or it is a constant unvarying current. A succession of distributed capacitors rules unvarying current out (and if it isn't already obvious, those unmentioned distributed inductors in one of your links do too) - hence the step, hence the infinity of waves, and from this, real world dispersion which kills the step enough to make that varying current apparent enough so as to remove all doubt. 73's Richard Clark, KB7QHC |
Loading Coils; was : Vincent antenna
Keith Dysart wrote:
On Dec 14, 9:40 am, Cecil Moore wrote: AI4QJ wrote: If it were possible for the source to provide DC current at c, then the DC current moves at c. The step function from zero to DC contains a lot of frequencies. I suspect photons are involved at the leading edge of the DC pulse. "Suspect" -- Perhaps like Inspector Clouseau? Humour aside, for transmission lines you should stick to charge, and distributed capacitance and inductance. This model is aptly capable and has no difficulties as the frequency drops so low that it becomes indistinguishable from DC. Why bother with photons? Only at the leading edge, you say. What explains the rest? Where is the energy stored? In the capacitance and inductance. Why not use the tools that work? Why try to force fit photons? ....Keith If we look at a tree from the north side, and then look at the same tree from the south side, we have looked at only one tree but we have seen it from two perspectives. Zo = sq. rt. L/C = 1/cC Inductance can be described as L = 1/((c^2)*C) (inductance per length) So is the energy stored in the inductance or in the capacitance. Two ways of looking at the same tree. 73, Roger, W7WKB |
Loading Coils; was : Vincent antenna
Richard Clark wrote:
On Fri, 14 Dec 2007 05:18:03 -0800, "Roger Sparks" wrote: That IS what I said. Think of the velocity as a moving wall, with the capacitor charged behind the wall, uncharged in front of the moving wall. .... Be real. This experiment can be performed, and the DC switched as frequently as desired. How square the wave front will be depends upon real world factors. Go to a transmission line characteristics table and use the formula to compare Zo, capacity per length, and line velocity. It will amaze you. Hi Roger, Take a deep breath, exhale, give what's above some more thought in light of many objections. Now, tells us just what significance any of this has in relation to already well established line mechanics? It certainly isn't different within the confines of its limitations if that is what you are trying to impress upon the group. I suppose for a mental short-cut it has some appeal, we get too many theories here based on approximations to stricter math. One such example is when an equation of approximation has forgotten the underlying |absolute value| and suddenly an inventor arrives with a "new" theory that discovers uses for negative solutions. Further, there is nothing DC about it at all. DC is either static (and in spite of Arthur's corruption of the term, that means no movement whatever) or it is a constant unvarying current. A succession of distributed capacitors rules unvarying current out (and if it isn't already obvious, those unmentioned distributed inductors in one of your links do too) - hence the step, hence the infinity of waves, and from this, real world dispersion which kills the step enough to make that varying current apparent enough so as to remove all doubt. 73's Richard Clark, KB7QHC Hi Richard, The math seems to work, but if you have no use for it, disregard it. On the other hand, if another perspective of electro magnetics that conforms to traditional mathematics can provide additional insight, use it. I am surprised at your criticism in using DC. To me, a square wave is DC for a short time period. Is the observation that a square wave can be described as a series of sine waves troubling to you? Perhaps the observation that a square wave might include waves of a frequency so high that they would not be confined in a normal transmission line is surprising or troubling to you? My goal is to better understand electromagnetic phenomena. You have given some very astute insight many times in the past and thanks for that. Negative comment is equally valuable, but sometimes a little harder to swallow. 73, Roger, W7WKB |
Loading Coils; was : Vincent antenna
On Dec 14, 9:40 am, Cecil Moore wrote:
AI4QJwrote: If it were possible for the source to provide DC current at c, then the DC current moves at c. The step function from zero to DC contains a lot of frequencies. I suspect photons are involved at the leading edge of the DC pulse. -- 73, Cecil http://www.w5dxp.com Right, the step function has a number of sinusoids associated with it which are affected by Zo and that was already addressed. Richard's challenge was to address the velocity of DC at steady state, after the transients from the step died down. |
Loading Coils; was : Vincent antenna
On Fri, 14 Dec 2007 09:45:04 -0800, Roger wrote:
Hi Richard, The math seems to work, but if you have no use for it, disregard it. On the other hand, if another perspective of electro magnetics that conforms to traditional mathematics can provide additional insight, use it. Hi Roger, This does not answer why TWO mathematics (both traditional) are needed, especially since one is clearly an approximation of the other, and yet offers no obvious advantage. I've already spoken to the hazards of approximations being elevated to proof by well-meaning, but slightly talented amateurs. I am surprised at your criticism in using DC. To me, a square wave is DC for a short time period. This single statement, alone, is enough to be self-negating. You could as easily call a car with a standard stick shift an automatic between the times you use the clutch - but that won't sell cars, will it? Is the observation that a square wave can be described as a series of sine waves troubling to you? Perhaps the observation that a square wave might include waves of a frequency so high that they would not be confined in a normal transmission line is surprising or troubling to you? DC as sine waves is not a contradiction on the face of it? DC that consists of waves of a frequency so high that it would not be confined in a normal transmission line is very surprising, isn't it? Would it surprise you to find your batteries in their packaging direct from the store are radiating on the shelf? They are DC, are they not? If the arguments of your sources works for an infinite line, they must be equally true for an infinitesimal open line. When your headlights are on, do they set off radar detectors in cars nearby because of the high frequencies now associated with DC? My goal is to better understand electromagnetic phenomena. You have given some very astute insight many times in the past and thanks for that. Negative comment is equally valuable, but sometimes a little harder to swallow. The pollution of terms such as DC to serve a metaphor that replaces conventional line mechanics is too shallow glass to attempt to quench any thirst. The puzzle here is the insistence on hugging DC, when every element of all of your links could as easily substitute Stepped Wave and remove objections. The snake in the wood pile is once having fudged what DC means, it is only a sideways argument away from rendering the term DC useless. Is the term Stepped Wave (the convention) anathema for a leveraging the novel origination (the invention) of DC Wave? 73's Richard Clark, KB7QHC |
Loading Coils; was : Vincent antenna
On Dec 14, 11:10 am, Cecil Moore wrote:
Keith Dysart wrote: Why bother with photons? Because it is impossible for electrons to move fast enough to explain the measured results. There is indeed a "DC" *wavefront* moving at the speed of light adjusted for VF. Electrons cannot move that fast. What is happening is that fast photons are skipping from slow electron to slow electron. Do photons also explain how sound can move at a 1000 ft/s, while the air molecules barely move at all? No? Not clear then why they are needed for electrons. ....Keith |
Loading Coils; was : Vincent antenna
Roger wrote:
I am surprised at your criticism in using DC. To me, a square wave is DC for a short time period. Is the observation that a square wave can be described as a series of sine waves troubling to you? Perhaps the observation that a square wave might include waves of a frequency so high that they would not be confined in a normal transmission line is surprising or troubling to you? Anyone who has ever tried to send a DC pulse down a long transmission line has seen AC ringing at the other end. -- 73, Cecil http://www.w5dxp.com |
Loading Coils; was : Vincent antenna
Richard Clark wrote:
The puzzle here is the insistence on hugging DC, when every element of all of your links could as easily substitute Stepped Wave and remove objections. How about "continuous wave" for Morse code? -- 73, Cecil http://www.w5dxp.com |
Loading Coils; was : Vincent antenna
Keith Dysart wrote:
Do photons also explain how sound can move at a 1000 ft/s, while the air molecules barely move at all? No, mechanical longitudinal waves are well understood. It is impossible for them to achieve the speed of light. No? Not clear then why they are needed for electrons. Do you think electrons support mechanical waves? The fields of TEM waves consist of photons traveling at the speed of light. -- 73, Cecil http://www.w5dxp.com |
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