|
Current through coils
On Mon, 3 Apr 2006 09:35:16 -0400, "Yuri Blanarovich"
wrote: So far, it looks to me that this exercise is worthwhile if we can improve the accuracy of modeling and our understanding of the phenomena. Hi Yuri, If you can't give me a metric of what the accurcy IS, then you cannot say you've improved or worsened it at the end of the process, can you? Like I said, "What's all the fuss over? What's to be proven? and How do we know when it has BEEN proven?" You aren't providing any forward momentum. 73's Richard Clark, KB7QHC |
Current through coils
Thanks, Tom.
In fact, let's get back to something very basic about antennas. Acceleration of CHARGE results in electromagnetic RADIATION. RADIATION impinging on a receiving antenna (and on anything else that freely transports charge) causes acceleration of CHARGE within that antenna. So when we are talking about antennas, it is very appropriate to be talking about charge, and exactly what happens to it to move it around and to accelerate it as a function of time, everywhere in the structure. A voltage applied to the feedpoint terminals of an antenna causes CHARGE to be put into motion. Accumulation of CHARGE along the conductors--the distribution of charge as a function of time and space--in turn results in electric fields in the vicinity of the antenna. Motion of charge results in magnetic fields in the vicinity of the antenna. Capacitance and inductance are manifestations of the electric and magnetic fields, respectively. Taken as a whole, the motion of charge and the resulting electric and magnetic fields give rise to waves: the waves, too, are manifestations of the electric and magnetic fields. ALL of these are consistent with each other, and to a very good approximation agree with the descriptions worked out by Faraday, Gauss, Maxwell and all many years ago. (We don't need quantum theory to be talking about performance of an 80 meter mobile antenna!) Please, let's keep it straight that the motion of charge is FUNDAMENTAL to all this analysis, and everything else will fall out very nicely from an accurate accounting of the motion of charge within the system. It is NOT irrelevant at all; it is at the very heart of the operation of ALL antenna systems. Cheers, Tom |
Current through coils
K7ITM wrote:
"Cyclical variation in charge (contained within a volume)" means that on average the charge stays constant, but it does not mean that it's constant over some arbitratily short but finite length of time. The current reported by EZNEC is RMS current, Tom. What happens within a cycle is irrelevant to this discussion. We are not and never have been discussing variations within a cycle. There's just no point. We have been discussing RMS values of currents. Your attempt to again divert the issue is noted. We are talking about net charge spread out over many steady-state cycles. That net charge is always zero no matter what the RMS value of the standing wave current at the ends of the coil. Without the capacitance, without the ability to store charge, a transmission line, an antenna wire, a loading coil, all of them--would not have the ability to cause delay. Freespace, without a non-zero permittivity (capacitance), would allow infinite speed of light. But all these things DO have capacitance, and they DO have speed-of-propagation at the speed of light or slower. Please tell us something we don't already know. It has become apparent that the discussion is not about coils at all. It is about the nature of standing waves whether existing in a transmission line, a standing wave antenna wire, or a coil. -- 73, Cecil http://www.qsl.net/w5dxp |
Current through coils
Tom Donaly wrote:
Cecil, since you always leave the phase information out of your version of the solution of the wave equation, I don't think Diogenes is going to be knocking on your door anytime soon, either. I'm not leaving phase out, Tom, Mother Nature leaves phase out of the standing wave equation. What is it about Gene Fuller's posting that you don't understand? Regarding the cos(kz)*cos(wt) term in a standing wave: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. The only "phase" remaining is the cos (kz) term, which is really an amplitude description, not a phase. -- 73, Cecil http://www.qsl.net/w5dxp |
Current through coils
|
Current through coils
Tom Donaly wrote:
There is no "net" charge storage on a capacitor in an AC environment, either, Cecil, but you can still get current to go through it. True, but completely irrelevant to the present discussion so more than likely another straw man. Once more, the subject is the RMS standing wave envelope reported by EZNEC. Brownian motion of individual electrons is completely irrelevant. -- 73, Cecil http://www.qsl.net/w5dxp |
Current through coils
Hey, Cecil, have you read "Freakonomics"? (Yes, it's relevant to the
discussion.) |
Current through coils
Tom, K7ITM wrote:
"A voltage applied to the feedpoint terminals of an antenna causes CHARGE to be put in motion. Accumulation of CHARGE along the conductors--the distribution of charge as a function of time and space--in turn results in electric fields in the vicinity of the antenna." Agreed that current is charge in motion. Accumulation of charge, however, is a job for an accumulator, another name for a storage battery. These have little to do with the possibility of an antenna coil having currents through the coil from opposite directions creating unequal totals at the ends of the coil. I don`t know if this Tom is picking a fight to gain attention before going to Dayton but his postings have the right fragarance. Best regards, Richard Harrison, KB5WZI |
Current through coils
Cecil Moore wrote:
Tom Donaly wrote: Cecil, since you always leave the phase information out of your version of the solution of the wave equation, I don't think Diogenes is going to be knocking on your door anytime soon, either. I'm not leaving phase out, Tom, Mother Nature leaves phase out of the standing wave equation. What is it about Gene Fuller's posting that you don't understand? Regarding the cos(kz)*cos(wt) term in a standing wave: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. The only "phase" remaining is the cos (kz) term, which is really an amplitude description, not a phase. Well, I guess it's o.k. for you to believe that when a wave travels down a transmission line it always ends up in phase with where it started. That simplifies things for your theory. It doesn't make for a very good transmission line, though. 73, Tom Donaly, KA6RUH |
Current through coils
Richard Harrison wrote:
Tom, K7ITM wrote: "A voltage applied to the feedpoint terminals of an antenna causes CHARGE to be put in motion. Accumulation of CHARGE along the conductors--the distribution of charge as a function of time and space--in turn results in electric fields in the vicinity of the antenna." Agreed that current is charge in motion. Accumulation of charge, however, is a job for an accumulator, another name for a storage battery. These have little to do with the possibility of an antenna coil having currents through the coil from opposite directions creating unequal totals at the ends of the coil. I don`t know if this Tom is picking a fight to gain attention before going to Dayton but his postings have the right fragarance. Best regards, Richard Harrison, KB5WZI If you don't understand the post, I guess a cheap shot is better than no shot at all. 73, Tom Donaly, KA6RUH |
| All times are GMT +1. The time now is 05:35 AM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com