| Home |
| Search |
| Today's Posts |
|
|
|
#1
|
|||
|
|||
|
No, I don't have a problem, nor did I make a mistake. I presented an
example with voltages, currents, and powers that are all self-consistent, obey Ohm's and Kirchoff's laws, and don't violate any physical laws. It simply uses those laws, equations that can be found in nearly any transmission line text, and arithmetic. The analysis is correct as written. You've demonstrated that you're unable to produce a similar analysis which can be fit into your conception of how things work. If your problem is dyslexia or unfamiliarity with complex arithmetic, all you have to do is say so. Neither is anything to be ashamed of. I now return the readers to the standard flurry of hand-waving, objecting, dodging, and excuses. But don't expect an analysis, derivation, or proof. And I'll be back outta here. Roy Lewallen, W7EL W5DXP wrote: Roy, you are the one who made the mistake. I have told you exactly what your mistake is. The rest is your problem, not mine. . . . |
|
#2
|
|||
|
|||
|
Roy Lewallen wrote:
No, I don't have a problem, nor did I make a mistake. I presented an example with voltages, currents, and powers that are all self-consistent, obey Ohm's and Kirchoff's laws, and don't violate any physical laws. It simply uses those laws, equations that can be found in nearly any transmission line text, and arithmetic. The analysis is correct as written. Nope, it isn't and after following all those laws, you violated one you should have learned in the 4th grade, i.e. to collect like terms. You've demonstrated that you're unable to produce a similar analysis which can be fit into your conception of how things work. No I haven't. I have produced a simple logical analysis that proved yours to be wrong. Do you really believe yourself incapable of making a conceptual error? In the following: ---lossy line---x---1WL 50 ohm lossless line---10+j50 load Pfwd1-- Pfwd2-- = 30.53W rho=0.82 at 88.9 deg --Pref1 --Pref2 = 20.53W I measure ten volts across the ten ohm resistor. I measure 30.53W forward on the 50 ohm line and 20.53W reflected on the 50 ohm line. Since the 50 ohm line is lossless, the forward voltage is in phase with the forward current and the reflected voltage is in phase with the reflected current. The values of voltages and currents on the 50 ohm line are easy to calculate. The load reflection coefficient is easy to calculate. Analysis from 'x' to the load is a no-brainer. The forward power on the 50 ohm line is 10W less than the reflected power on the 50 ohm line, i.e. Pfwd2-Pref12 = 10W just as it should. At point 'x', on the source side of 'x', Pfwd1-Pref1 MUST equal that same 10W. It doesn't matter what happens between 'x' and the source. At point 'x', Pfwd1 simply cannot be less than Pref1. Conditions are the same whether the 1WL of lossless 50 ohm feedline is in the circuit or out of the circuit. You have not taken all the forward and reflected terms into account. You have violated something you should have learned in the 4th grade, i.e. to collect like terms. Instead, you threw away half of the forward terms and half of the reflected terms. No wonder you got it wrong. -- 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! =----- |
|
#3
|
|||
|
|||
|
Cecil Moore wrote:
Roy Lewallen wrote: No, I don't have a problem, nor did I make a mistake. I presented an example with voltages, currents, and powers that are all self-consistent, obey Ohm's and Kirchoff's laws, and don't violate any physical laws. It simply uses those laws, equations that can be found in nearly any transmission line text, and arithmetic. The analysis is correct as written. Nope, it isn't and after following all those laws, you violated one you should have learned in the 4th grade, i.e. to collect like terms. You've demonstrated that you're unable to produce a similar analysis which can be fit into your conception of how things work. No I haven't. I have produced a simple logical analysis that proved yours to be wrong. Do you really believe yourself incapable of making a conceptual error? In the following: ---lossy line---x---1WL 50 ohm lossless line---10+j50 load Pfwd1-- Pfwd2-- = 30.53W rho=0.82 at 88.9 deg --Pref1 --Pref2 = 20.53W I measure ten volts across the ten ohm resistor. I measure 30.53W forward on the 50 ohm line and 20.53W reflected on the 50 ohm line. Since the 50 ohm line is lossless, the forward voltage is in phase with the forward current and the reflected voltage is in phase with the reflected current. The values of voltages and currents on the 50 ohm line are easy to calculate. The load reflection coefficient is easy to calculate. Analysis from 'x' to the load is a no-brainer. The forward power on the 50 ohm line is 10W less than the reflected power on the 50 ohm line, i.e. Pfwd2-Pref12 = 10W just as it should. At point 'x', on the source side of 'x', Pfwd1-Pref1 MUST equal that same 10W. It doesn't matter what happens between 'x' and the source. At point 'x', Pfwd1 simply cannot be less than Pref1. I observe that you make the assertion, but fail to do the arithmetic to demonstrate the assertion, while Roy does the arithmetic which seems to contradict your assertion. There is a strong suspicion that the reason you don't do the arithmetic (since you do seem fond of numerical examples) in this case is that you have been unable to make arithmetic produce the desired result. Note that a requirement for Vr to be greater than Vf is that the reactive component of the load has a different sign than the reactive component of the line. So the problem specification is incomplete. Since the reactances on each side of 'x' have different signs, the circuit looks like it might be somewhat resonant and it should not be a surprise when resonant circuits produce higher voltages. ....Keith |
| Reply |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|