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#1
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On Wed, 02 Jun 2004 16:49:09 GMT, Walter Maxwell wrote:
On Wed, 02 Jun 2004 08:37:30 -0500, Cecil Moore wrote: Walter Maxwell wrote: wrote: Steve at first said the energy in the canceled waves continues to flow toward the source without a voltage and current and that interference was not involved. He later changed his mind. All that should be archived on r.r.a.a on Google for the summer of 2001. Here's an excerpt. Steve said: "The total forward power increases as a direct result of the vector superposition of forward voltage and current. This DOES NOT require a corresponding destructive interference process ..." thus contradicting Hecht in _Optics_ who says any constructive interference process must be accompanied by an equal magnitude of destructive interference. Superposition of forward voltage and current? I'm sure he meant "superposition of forward voltages and superposition of forward currents." I don't recall Steve ever mentioning current. I think you are right re his article. The above quote is from an r.r.a.a. posting circa Summer 2001. What Steve apparently doesn't understand is how the energy direction is reversed when the rearward voltages and currents go to zero. "How" is not explained in any of the physics references. The closest physics reference that explains it is _Optics_, by Hecht where he says something like, at a point some distance from a source, constructive interference must be balanced by an equal magnitude of destructive interference. In a matched system, there is "complete destructive interference" toward the source side of the match point and "complete constructive interference" toward the load side of the match point. Energy is always displaced from the "complete destructive interference" event to the "complete constructive interference" event. (That's what you call a "virtual short" or "virtual open" capable of re-reflecting the reflected energy.) Cecil, I explained the 'how', both in Reflections and in QEX. My explantion of 'how' is what Steve is continually stating is incorrect, especially in his last 3-part QEX article. Statements in that article prove he doesn't understand the wave mechanism that reverses the direction of the reflected energy. Evidence of this is that by simply saying the voltages cancel is insufficient description of how the energies reverse direction. In fact, in his Oct 99 ComQuart article he specifically states that both voltages and power cancel. This tell me that he doesn't understand the wave action he's attempting to teach. MIT's Slater and Harvard's Alford both explain it brilliantly, but Steve rejects those references as 'irrelevant', and says I mistakenly used them as references in Reflections. What is really perplexing to me is that several posters on this subject said that Steve's 3-parter is the best and most illuminating article they ever read on the subject. How can they have missed some of the most egregious errors appearing in that paper is unbelievable! snip Cecil, the following is a direct quote from Steve's Comm Quart Article, Oct 1999: "For the impedance matching network to 'work', this analysis must demonstrate that the steady-state traveling backward power developed at the matching network input is equal in magnitude but 180 degrees out of phase with the initial power reflected at the matching network input. For this to occur Vback must be the negative of VR. In this case ALL POWER TRAVELING BACKWARD TOWARDS THE TRANSMISTTER WILL BE CANCELED, resulting in the steady-state matched condition." Emphasis mine. Walt |
#2
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Walter Maxwell wrote:
Cecil, the following is a direct quote from Steve's Comm Quart Article, Oct 1999: "For the impedance matching network to 'work', this analysis must demonstrate that the steady-state traveling backward power developed at the matching network input is equal in magnitude but 180 degrees out of phase with the initial power reflected at the matching network input. For this to occur Vback must be the negative of VR. In this case ALL POWER TRAVELING BACKWARD TOWARDS THE TRANSMISTTER WILL BE CANCELED, resulting in the steady-state matched condition." Joules/sec possesses phase? Joules/sec can be canceled? -- 73, Cecil http://www.qsl.net/w5dxp |
#3
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![]() Cecil Moore wrote: Walter Maxwell wrote: Cecil, the following is a direct quote from Steve's Comm Quart Article, Oct 1999: "For the impedance matching network to 'work', this analysis must demonstrate that the steady-state traveling backward power developed at the matching network input is equal in magnitude but 180 degrees out of phase with the initial power reflected at the matching network input. For this to occur Vback must be the negative of VR. In this case ALL POWER TRAVELING BACKWARD TOWARDS THE TRANSMISTTER WILL BE CANCELED, resulting in the steady-state matched condition." Joules/sec possesses phase? Joules/sec can be canceled? Therein lies part of the problem with thinking that the unit (Joules/sec) moves along a transmission line. Energy in Joules moves. (Joules/sec) of power does not. 73, Jim AC6XG |
#4
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On Thu, 03 Jun 2004 12:44:10 -0700, Jim Kelley wrote:
Cecil Moore wrote: Walter Maxwell wrote: Cecil, the following is a direct quote from Steve's Comm Quart Article, Oct 1999: "For the impedance matching network to 'work', this analysis must demonstrate that the steady-state traveling backward power developed at the matching network input is equal in magnitude but 180 degrees out of phase with the initial power reflected at the matching network input. For this to occur Vback must be the negative of VR. In this case ALL POWER TRAVELING BACKWARD TOWARDS THE TRANSMISTTER WILL BE CANCELED, resulting in the steady-state matched condition." Joules/sec possesses phase? Joules/sec can be canceled? Hi Jim, Of course you're right, but that's not the point. The point is that reflected energy is not canceled, nor does it disappear at the matching point, instead it is re-reflected into the forward direction. This is the point that Steve apparently doesn't understand. And this is the reason his power budget is incorrect in his 3-part article, he ignored the energy appearing at the match point, assuming that it disappeared, though his word is 'canceled'. I thought my emphasis with capitalization would contain the necessary info, but I can see now that I should have made the emphasis show that the 'canceled energy' was erroneous, because energy cannot be canceled. In this case it is re-reflected, a concept Steve ignores. Therein lies part of the problem with thinking that the unit (Joules/sec) moves along a transmission line. Energy in Joules moves. (Joules/sec) of power does not. 73, Jim AC6XG Sorry, Jim, I put my response in the wrong place. Walt |
#5
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Jim Kelley wrote:
Therein lies part of the problem with thinking that the unit (Joules/sec) moves along a transmission line. Energy in Joules moves. (Joules/sec) of power does not. What about the Poynting Vector and Power Flow Vectors? What about the 60 Hz "power generation" and "power distribution" system? Are you saying that the trailing edge of an ExH wave is not moving? Are you saying that the ExB power in the light from Alpha Centauri didn't come from Alpha Centauri? -- 73, Cecil http://www.qsl.net/w5dxp |
#6
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Cecil Moore wrote:
Jim Kelley wrote: Therein lies part of the problem with thinking that the unit (Joules/sec) moves along a transmission line. Energy in Joules moves. (Joules/sec) of power does not. What about the Poynting Vector and Power Flow Vectors? What about them? What about the 60 Hz "power generation" and "power distribution" system? What are you trying to imply about power generation? "Power distribution system" is really a misnomer. In the present day venacular it would be called exactly what it is - an "energy distribution system". Are you saying that the trailing edge of an ExH wave is not moving? I don't recall ever expressing the opinion that traveling waves don't travel. However mathematical formulas do not propagate along transmission lines. Fields do, but there is no such thing as an ExB "field". 73, Jim AC6XG |
#7
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Jim Kelley wrote:
... there is no such thing as an ExB "field". Good grief, Jim, ExB is proportional to the irradiance of a light beam. I'm sorry if my ASCII-limited character set hairlips you. -- 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! =----- |
#8
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![]() Cecil Moore wrote: Jim Kelley wrote: ... there is no such thing as an ExB "field". Good grief, Jim, ExB is proportional to the irradiance of a light beam. Good grief, Cecil, irradiance isn't a field and doesn't propagates either! 73, Jim AC6XG |
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