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#1
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On Mar 12, 10:17 am, Cecil Moore wrote:
Keith Dysart wrote: Actually, we have shown that that is not the case. If the instantaneous power is not dissipated in the source resistor, then neither is the average of the instantaneous power. And we have shown that the instantaneous power is not dissipated in the source resistor. Actually, we have shown exactly the opposite. Maybe a different example will help. We are going to replace the 23.5+j44.1 ohm load with a *phase-locked* signal generator equipped with a circulator and 50 ohm load. The signal generator supplies 18 watts back to the original source and dissipates all of the incident power of 50 watts, i.e. all of the forward power from the original source. The original source sees *exactly the same 23.5+j44.1 ohms as a load*. Rs Vg +----/\/\/-----+----------------+--2---1-----+ | 50 ohm \ / | | 3 18 watt Vs 1 wavelength | Signal 100v RMS 50 ohm line 50 Generator | ohms | | | | +--------------+----------------+----+-------+ gnd gnd The conditions at the original source are identical. The circulator load resistor is dissipating the 50 watts of forward power supplied by the original source. The signal generator is sourcing 18 watts. Your instantaneous power equations have not changed. Are you going to try to tell us that the 18 watts from the signal generator are not dissipated in Rs???? If not in Rs, where???? As you note, the conditions at the original source have not changed, so, since the energy in the reflected wave was not dissipated in the source resistor in the original circuit, it is not dissipated there in the revised circuit. So, no changes at the original source. Let us look at the circulator. Assuming a circulator which does not accumulate energy, the net energy into circulator must be zero. 0 = Pcp1(t) + Pcp2(t) + Pcp3(t) Let us start with the 18 W producing 0 output. Let us turn on the original source Pg(t) = 50 + 50cos(2wt) After one cycle, the wave reaches the circulator, so at the circulator Pcp1(t) = 0 Pcp2(t) = 50 + 50cos(2wt) Pcp3(t) = -50 - 50cos(2wt) which satisifies 0 = Pcp1(t) + Pcp2(t) + Pcp3(t) Now turn on the right signal generator set to produce 18 W. Using the phase relationship needed to reproduce the conditions from the original experiment Pcp1(t) = 18 - 18cos(2wt) This alters the voltage and current conditions at Port 2 of the circulator so that power delivered to this port is now Pcp2(t) = 32 + 68cos(wt) and the power into Port 3 remains Pcp3(t) = -50 - 50cos(2wt) which still satisfies 0 = Pcp1(t) + Pcp2(t) + Pcp3(t) Since turning on the 18 W generator altered the conditions at Port 2, this change in line state propagates back towards the original source and this state change reaches point Vg Pg.before(t) = 50 + 50cos(2wt) changes to Pg(t) = 32 + 68cos(2wt) which is good since this is the same power extracted from the line at the circulator. The changed load conditions at Vg alter the dissipation in the source resistor as well as changing the power delivered by the voltage source. So where is the 18 Watts from the generator dissipated? This is obvious. When the 18 W generator was turned on, the power delivered to the circulator from the line (i.e. the power delivered into Port 2, Pcp2(t) above) dropped, but the power dissipated in the 50 ohm resistor stayed the same. So it must be that the 18 W from Port 1 is now being used to heat the resistor attached to Port 3. ....Keith |
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#2
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Keith Dysart wrote:
So where is the 18 Watts from the generator dissipated? This is obvious. When the 18 W generator was turned on, the power delivered to the circulator from the line (i.e. the power delivered into Port 2, Pcp2(t) above) dropped, but the power dissipated in the 50 ohm resistor stayed the same. So it must be that the 18 W from Port 1 is now being used to heat the resistor attached to Port 3. Keith, I'm going to now leave you alone with your new religion. Good grief! -- 73, Cecil http://www.w5dxp.com |
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#3
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Keith Dysart wrote:
So where is the 18 Watts from the generator dissipated? This is obvious. When the 18 W generator was turned on, the power delivered to the circulator from the line (i.e. the power delivered into Port 2, Pcp2(t) above) dropped, Sorry Keith, that's not the way circulators work. The power incident upon port 2 does NOT change when the 18w generator is turned on. -- 73, Cecil http://www.w5dxp.com |
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#4
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On Mar 14, 12:49*am, Cecil Moore wrote:
Keith Dysart wrote: So where is the 18 Watts from the generator dissipated? This is obvious. When the 18 W generator was turned on, the power delivered to the circulator from the line (i.e. the power delivered into Port 2, Pcp2(t) above) dropped, Sorry Keith, that's not the way circulators work. The power incident upon port 2 does NOT change when the 18w generator is turned on. You need to read more carefully. I made no statement about the energy incident upon port 2, only about the energy flowing into port 2, which, after the 18 W generator is turned on, is Pcp2(t) = 32 + 68cos(wt) ...Keith |
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#5
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Keith Dysart wrote:
You need to read more carefully. I made no statement about the energy incident upon port 2, only about the energy flowing into port 2, which, after the 18 W generator is turned on, is Pcp2(t) = 32 + 68cos(wt) If we have two pipes each carrying one gallon of water per minute in opposite directions, we can agree that the net flow of water is zero. But you are taking it one step farther and arguing there is no water flowing at all which is a ridiculous assertion. I'm going to ignore this latest obvious diversion. -- 73, Cecil http://www.w5dxp.com |
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#6
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On Mar 14, 8:08*am, Cecil Moore wrote:
Keith Dysart wrote: You need to read more carefully. I made no statement about the energy incident upon port 2, only about the energy flowing into port 2, which, after the 18 W generator is turned on, is Pcp2(t) = 32 + 68cos(wt) If we have two pipes each carrying one gallon of water per minute in opposite directions, we can agree that the net flow of water is zero. But you are taking it one step farther and arguing there is no water flowing at all which is a ridiculous assertion. I'm going to ignore this latest obvious diversion. -- 73, Cecil *http://www.w5dxp.com If there were two transmission lines, then I could see why you might want two pipes in an analogy. But since there is only one transmission line, an analogy with one pipe makes more sense. So you want to argue that when there is one pipe with no water flowing, what is really happening is that one gallon per minute is simultaneously flowing in each direction. In the same pipe. At the same time. I don't buy it. You should think a bit more about Pcp2(t) = 32 + 68cos(wt) It is the time rate of energy flow into the port. It can trivially be computed from the voltage and current functions at that port. It sums with the energy flows into the other ports appropriately to satisfy the principle of conservation of energy. All is well. And there is only one pipe for each port. ...Keith |
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#7
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Keith Dysart wrote:
If there were two transmission lines, then I could see why you might want two pipes in an analogy. But since there is only one transmission line, an analogy with one pipe makes more sense. Unfortunately for your argument, molecular water and EM waves are considerably different animals. Water energy traveling in opposite directions in a pipe interact. EM waves traveling in opposite directions in a transmission line interact only at an impedance discontinuity or at an impedor. As long as only a constant Z0 environment exists, the forward wave and reflected wave pass like ships in the night. For you to prove otherwise, you are going to have to define the position and momentum of a single photon. Good luck on that one. -- 73, Cecil http://www.w5dxp.com |
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#8
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On Mar 14, 5:29*pm, Cecil Moore wrote:
Keith Dysart wrote: If there were two transmission lines, then I could see why you might want two pipes in an analogy. But since there is only one transmission line, an analogy with one pipe makes more sense. Unfortunately for your argument, molecular water and EM waves are considerably different animals. Water energy traveling in opposite directions in a pipe interact. EM waves traveling in opposite directions in a transmission line interact only at an impedance discontinuity or at an impedor. As long as only a constant Z0 environment exists, the forward wave and reflected wave pass like ships in the night. For you to prove otherwise, you are going to have to define the position and momentum of a single photon. Good luck on that one. I accept your retraction of your analogy. ...Keith |
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