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Cecil Moore wrote:
wrote: I have often suspected that it is the existence and use of 'Bird watt' meters that has convinced so many of the existence of forward and reverse power; a belief which many seem absolutely unwilling to relax their hold on despite the difficulties it causes them. OTOH, a TDR causes you difficulties. And just how do you explain standing waves without a forward wave and a reflected wave? Can you expand on why you think a TDR causes me difficulties? I can't think of any reasons. As for standing waves, I have no difficulties with forward and reflected voltage waves. They work perfectly fine. ....Keith |
Cecil Moore wrote:
wrote: Of course if you let go of Pfwd and Pref and just used Vfwd and Vref you would quickly learn that you had no interest in Pfwd and Pref and thus your inability to determine them would not cause you much distress. Uh Keith, radiated *POWER* is what we are trying to get from our antennas. Yes indeed. Net power. The only power that counts. Pnet = average( v(t) * i(t) ) Forget that forward and reverse stuff. That's not what is radiated. ....Keith |
Roy Lewallen wrote:
I've done my analysis, and am satisfied with it. That's why I don't rearrange things to suit your view of reality. I've never before seen a person so proud of a contradiction. If reflected power is greater than forward power, then the Poynting vector points away from the load, but you have said it doesn't. So which is it? Why are you unable to calculate the correct terms, collect them, or whatever you think necessary, and show us what values they are and how they add up to give us the forward and reverse powers you hypothesize? I don't choose to waste my time on such a no-brainer issue. If the Poynting vector points toward the load, the reflected power cannot be greater than the forward power. Chipman goes out of his way to indicate that such an apparent contradiction is caused by a resonance effect. The opposite sign of the reactance of Z0 Vs the load is re-reflecting energy back to the load because the load resistance is in series with the inductive reactance of the load and the capacitive reactance of the feedline. The re-reflected energy supplied by the capacitive reactance becomes forward power in the resistance. That's why the Poynting vector points toward the load. According to Chipman, that's why forward power minus reflected power CANNOT be negative. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
wrote:
Can you expand on why you think a TDR causes me difficulties? I can't think of any reasons. There's more than just voltage in those returned pulses. As for standing waves, I have no difficulties with forward and reflected voltage waves. They work perfectly fine. That takes care of the E-field. But do you think a wave can exist without an H-field? If not, the wave possesses energy, by definition. Energy flowing past a point is power. Your voltage-only waves violate the conservation of energy principle and the accepted laws of physics for EM waves. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
wrote:
Forget that forward and reverse stuff. That's not what is radiated. Uh Keith, power delivered to the antenna equals forward power minus reflected power. I notice you have not provided a way for standing waves to develop without the existence of reflected waves. Do you also believe that standing waves don't exist? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
wrote:
When you use a pulse, p(t) = v(t) * i(t) shows the pulse going by and coming back too, if it reflects. But for that, you have to look at things in the time domain, something a number of readers here refuse to do for continuous sinusoidal excitation. When you look at continuous sinusoidal excitation in the time domain all the information you need about power is provided without having to resort to Pfwd and Prev. Yes, but those steady-state shortcuts often lead to a distorted view of reality. Exactly what magic happens at the instant when a system goes from the transient state to steady-state? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
"Cecil Moore" wrote in message ... Yes, but those steady-state shortcuts often lead to a distorted view of reality. Exactly what magic happens at the instant when a system goes from the transient state to steady-state? there is no magic, and real systems can never get to steady state. the steady state approximations are used by engineers who understand their limitations and know when they can apply them to easily get answers that are good enough for every day use. engineers who don't understand them can always use the full field equations and calculate the exact answers if they have the time and enough information about the system... but they will never be able to answer the question about forward and reflected power except at a specific instant in time and single location in the system as the transients never go away and power in is never equal to power out except by coincidence. |
On Fri, 19 Sep 2003 07:07:35 -0500, Cecil Moore
wrote: Your voltage-only waves violate the conservation of energy principle and the accepted laws of physics for EM waves. Hi Cecil, Problems of speed reading again afflict you. Or is it the phenomenon of copy machine hypnosis, where with each sweep of the light you acquire more virtual education? That technique works better if you hold single pages up instead while looking down through sunglasses. (Not nearly as expensive as tuition by the way ;-) From Chipman (no point in offer the page # is there?): "Postulate 4. At the intersection of any transverse plane with the line conductors there is a unique value of potential difference between the conductors at any instant..." As you reject Postulate 4 explicitly in your statement(s), you also reject your own arguments couched in Chipman's discussion that you cut-and-paste into your derivative works. Next time you ride your bike to the library, take the time to read Chipman's work instead of copying it. Given the nearly universal silence in this group to such insights offered above in the quote, it seems you should be in rather crowded circumstances competing to read that same volume - none here seem to have time to read nor quote the obvious. The kulture of Institutionalized Ignorance festers on. 73's Richard Clark, KB7QHC |
On Fri, 19 Sep 2003 13:58:36 -0000, "David Robbins"
wrote: "Cecil Moore" wrote in message ... Exactly what magic happens at the instant when a system goes from the transient state to steady-state? there is no magic, and real systems can never get to steady state. the steady state approximations are used by engineers who understand their limitations and know when they can apply them to easily get answers that are good enough for every day use. Hi David, This is the difference between Engineering and religion. All Engineering works with error and simply states the limits of confidence to known factors. That is 1 Ohm/Volt/Ampere to a tolerance of 20% or 10% or 5% or better. When differences between known boundary conditions far exceed the error of their determination, then you can rest assured that you have a solution that is an accurate portrayal of those different boundary conditions. (On reflection, even religion acknowledges error; so comparisons are an affront to that study as well. What goes on in these "debates" is simple, narcissistic laziness.) I offered a simple line loss problem some time ago to which there was only one correct submission (be e-mail no less). This problem approached this "debate" with known errors and the correspondent found a solution to within 0.06 dB while others, frozen in mental gridlock, failed to even choose the conventional "perfect" answer. In the work place they would be staring at the bench, transfixed in the agony of Zeno's paradox, while real techs (not even engineers) would have the problem whipped before the first break (and still had done productive work too). 73's Richard Clark, KB7QHC |
Richard Clark wrote:
From Chipman (no point in offer the page # is there?): "Postulate 4. At the intersection of any transverse plane with the line conductors there is a unique value of potential difference between the conductors at any instant..." As you reject Postulate 4 explicitly in your statement(s), ... Richard, you really need to grasp the difference between exclusive and inclusive statements. Keith implies a voltage-only wave. It is my understanding that an EM wave cannot exist without an associated H-field. Chipman doesn't say EM waves can exist without an H-field. EM waves possess both E-fields and H-fields. The power associated with an EM wave is E x H. An H-field around a wire implies a current in that wire. My objection to Keith's statement is his voltage-only wave existing without current, energy, or power. -- 73, Cecil, W5DXP |
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