Home |
Search |
Today's Posts |
#11
![]() |
|||
|
|||
![]()
On Jun 26, 12:22*am, Keith Dysart wrote:
On Jun 25, 7:30*am, K1TTT wrote: On Jun 25, 7:46*am, lu6etj wrote: On 24 jun, 17:54, K1TTT wrote: On Jun 24, 3:25*pm, Cecil Moore wrote: On Jun 24, 9:20*am, lu6etj wrote: Oh, I'm so sorry Cecil, I should have written "However I can not visualize a simple PHYSICAL mechanism/example to generate such system in a TL". Anyway, your additional info it is very useful to me. Thanks. The physical mechanism is the Z01==Z02 impedance discontinuity with its associated reflection coefficient, rho. We can see that reflection on a TDR so it is indeed a PHYSICAL mechanism. -- 73, Cecil, w5dxp.com don't forget the OTHER physical mechanism that is necessary, superposition... the ability to add voltages, currents, and fields in linear circuits and media. I mentioned same comment in another post. We use superposition principle in two different contexts. Superposition theorem in circuit theory, and wave superposition. Wave (traveling) superposition deals with f(t,x,y,z) and usually with puntual magnitudes, E, H, D, B, etc) while circuit theory deals with a subset f(t) phenomena and with integrated magnitudes (V, I). Sometimes that becomes a confused issue ![]() Miguel NO, superposition is always the same. *it is the linear addition of currents or fields in a linear media. *it works the same for circuits as for em waves. the big problem are the people who confuse the formulas for adding powers with adding fields or currents/voltages and forget the phase terms. the other big problem is keith who seems to want to separate his waves into separate time and space variables and leaves out the requirement that wave functions must be dependent on both space AND time. basically any solution to the wave equations derived from maxwell's laws must be of the form f(t-x/v). *this leads him to the erroneous conclusions he gets from trying to compare his batteries to wave propagation. *this is the same problem people have with standing waves, they have separate dependence on t and x, so they can't travel and can't transport energy.- Hide quoted text - I see that the stress induced by considering DC waves is causing you to misinterpret my writings. May I suggest an alternate exploration for you. Assuming that you accept TDR and know how to use Reflection Coefficients to compute voltage and current reflections, then consider what happens when a rectangular pulse is launched from a matched generator in to a transmission line. For simple reflection coefficients like 0, 1, and -1 compute the reflected pulse. For both the forward and reflected direction compute the voltage and current on the line before the pulse arrives, as it passes and after it has passed. Compute the energy in the pulse, and how long a distance it occupies on the transmission line. Compute the power as the pulse is passing. Be sure you know what happens to the pulse when it re-enters the generator. For simplicity, assume a generator constructed using the Thevenin circuit. Make sure all the results are in agreement; especially, the energy delived by the source and the energy dissipated in the various resistors. Now make the pulse longer and longer... until it looks like a step function. And do the computations again. Determine if the results agree with those I previously presented for the DC example. ...Keith PS: Barring errors, they will. why would i want to do all that work? there is no way that my answers will agree with your misconceptions. you'll just come up with an even uglier generator to try to make it fit. oh, and by the way, your fancy 2 generator and 2 resistor 'constant power' source isn't what you think it is. go back to basic circuits 101 and you will find that any linear network like that can be reduced to either a simple one source one impedance norton or thevenin equivalent. in your example it is identical to a 50v voltage source in series with a 50ohm resistor... deriving the norton equivalent is left for the student. |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Reflected Energy | Antenna | |||
Reflected power ? | Antenna |