| Home |
| Search |
| Today's Posts |
|
#11
November 29th 04, 12:02 AM
|
|||
|
|||
On Sun, 28 Nov 2004 18:41:44 GMT, Richard Clark
wrote: On Sat, 27 Nov 2004 21:43:14 GMT, (Robert Lay W9DMK) wrote: I can see now that the Additional Losses Due to SWR really are dissipative and are unrelated to the "Mismatch Losses" and "Transducer Losses" defined on page 22-12 of the ITT Handbook, 5th Ed. Hi Bob, I've let this simmer for a while, but I have to return to this because you've erred in interpretation of this particular page and those particular subjects. They are entirely caloric losses, not what you dismiss as the myth of mismatch loss. You need only review the math offered to observe they use the conventional "real" line loss and add more "real" line loss in proportion to the reflections at either one or two interfaces. The equations are quite literal to this and explicitly state: A0 = normal attenuation of line I goofed on the part that is talking about transducer loss. I should NOT have included the "Transducer Losses" in my statement above. The Transducer losses do, as you say, include the normal attenuation of the line, which is indeed a dissipative loss. If you want deeper math, one source can be found in Chipman's (as unread as any here) "Transmission Lines." This is yet another of my references that attend to my recent, short thread on the nature of power determination error, and mismatched loads AND sources. In fact ALL of these references I've offered explicitly describe that the source MUST be matched for ANY of these equations about transmission lines bandied about to accurately offer true answers. The naive presumptions that Source Z is immaterial to the outcome of analysis is quite widespread here. Chipman offers the rigorous math that attends explicitly to the Smith Chart loss nomograph you reference elsewhere in this thread. If you lack access to this work, I can munge up the equations here for you. I will add, this math is for "lossless" lines, as is the implication of the Smith Chart nomograph; but it only requires you to add that in for yourself by restructuring the math to include loss. At that level of granularity, it won't be pretty; but you can rest assured it will be complete. I'm not sure what you are saying about the loss nomograph on the Smith Chart. If that's wrong too, then we're in big trouble. Everything ever written that I have seen about the Smith Charts agrees that the actual losses in the transmission line are indicated by the collapsing of the circle as one traverses the transmission line. All you have to do is read the "loss in 1 dB steps" scale to determine those losses. Bob, W9DMK, Dahlgren, VA http://www.qsl.net/w9dmk |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| Current in antenna loading coils controversy - new measurement | Antenna | |||
| Complex line Z0: A numerical example | Antenna | |||
| A Subtle Detail of Reflection Coefficients (but important to know) | Antenna | |||
| Re-Normalizing the Smith Chart (Changing the SWR into the same load) | Antenna | |||
Threaded Mode
