Home |
Search |
Today's Posts |
#331
![]() |
|||
|
|||
![]()
Yuri Blanarovich wrote:
... To put it mildly: The biggest crock of sheeeet yet! bada BUm Could you possibly lighten up on the intellectual content of your posts--some of are "Yuri Challenged" yanno? JS |
#332
![]() |
|||
|
|||
![]()
Yuri Blanarovich wrote:
... Yuri K3BU.us Frankly, I DON'T think diversity is a good thing, any chance of convincing you we are all idiots and you would be better off returning to your country of birth? Well hell, just a thought ... :-D JS |
#333
![]() |
|||
|
|||
![]()
Tom Donaly wrote:
In other words, you can't do it. Why don't you just say so? In other words, I don't take stupid paths down the primrose lane. Here's one for you: If electrons were in the nucleus and protons orbited the nucleus, would RF waves still propagate the same way? -- 73, Cecil http://www.w5dxp.com |
#334
![]() |
|||
|
|||
![]()
Looks like I didn't miss much by being out of town for a few days. The
same arguments and hand-waving are still raging. But I'll try to add one constructive bit of information: NEC calculates field interactions by means of very fundamental and very well established electromagnetic principles. As a result, it does a very good job of predicting currents in an inductor which is modeled as a helix. There are some caveats as there always are with any modeling process, particularly: 1. The spacing between the outsides of the wires in adjacent turns should be at least one wire diameter, and ideally several. NEC does not account for uneven distribution of current around a wire (proximity effect). This mainly impacts effective resistance. 2. The whole model must do some radiating, although even very inefficient radiating structures are analyzed with good accuracy. A check of the average gain usually reveals if there's a problem with the overall calculation. I've gotten quite good results with a model consisting of a fairly small coil with a wire through the center connecting the coil ends, and a source at the middle of the wire. To the extent that the program is providing accurate results, it can be used as a verification or refutation of measurements, and to test whatever alternate theories one wants to propose. Cecil likes to split currents into sets of traveling waves, which in itself is fine. However, when all the waves are added together to produce the actual current, the result should agree with measurement and with analysis by established theory. This means that, again to the extent that the model calculations are being done correctly, the solution using traveling waves should agree with NEC modeling results. One huge advantage of using NEC results is that they're not limited by lumped constant, traveling wave, waveguide mode, or other approximations which hold only over some range of conditions. Results should transition from one to another smoothly since the same fundamental laws apply regardless of the regime. (One additional caveat, though, when doing analysis at extremely high frequencies: the wire circumference has to be no more than a small fraction of a wavelength, because as mentioned earlier the program does assume equal current distribution around the wire.) Of course, comparison of rigorous numerical measurements or modeling results with vague, hand-waving theories with no supporting equations or other mathematical tools is a total waste of the reader's time, and that's pretty much all that seems to be happening here. But if anyone is actually seriously interested in investigating alternative theories or analytical methods, NEC or derivative programs such as EZNEC can provide powerful assistance in confirming or refuting them. Unless, of course, the objective is an attempt to refute the validity of Maxwell's equations, in which case disagreement with NEC should be expected. Both NEC and EZNEC provide simple ways of generating a helical model. Roy Lewallen, W7EL |
#335
![]() |
|||
|
|||
![]()
Gene Fuller wrote:
In that paper he indicated various conditions for validity, such as the fact that the coil must be near a quarter wave resonance for some of the mathematical approximations to be valid. What he *didn't* say is that if that same coil is cut in half and used at the same frequency, the Z0 and VF change. -- 73, Cecil http://www.w5dxp.com |
#336
![]() |
|||
|
|||
![]()
Gene Fuller wrote:
Actually, the context has been the loading coil measured by W8JI. Actually, W8JI himself says the coil he used is similar to a 75m mobile loading coil. -- 73, Cecil http://www.w5dxp.com |
#337
![]() |
|||
|
|||
![]()
K7ITM wrote:
Others are welcome to ponder all that while Cecil tries to unstick himself from his tarbaby. It's your tarbaby, Tom, not mine. When you can tell me what's the difference between a duck, I will tackle your equally ridiculous questions. -- 73, Cecil http://www.w5dxp.com |
#338
![]() |
|||
|
|||
![]()
Roy Lewallen wrote:
... Roy Lewallen, W7EL Oh gawd, the voice of recon' and ruin returns! Don't question NEC/EZNEC, they are gods! Etc. ... Why not tear 'em open, maybe if we see the equations which these applications utilize we can make much better arguments? ... however, a childish belief in "magic" is cute, huh? As always, JS |
#339
![]() |
|||
|
|||
![]()
Cecil Moore wrote:
Tom Donaly wrote: In other words, you can't do it. Why don't you just say so? In other words, I don't take stupid paths down the primrose lane. Here's one for you: If electrons were in the nucleus and protons orbited the nucleus, would RF waves still propagate the same way? Why can't I stick photographic film between the windings in a large coil in HF range and get clouding of the film--apparently these photons are "different" and don't react with the emulsion? Sorry, I have a religious belief in EM radiation which does NOT involve photons ... :-( Now don't throw stones, I am just "reaching", JS |
#340
![]() |
|||
|
|||
![]()
Roy Lewallen wrote:
But if anyone is actually seriously interested in investigating alternative theories or analytical methods, NEC or derivative programs such as EZNEC can provide powerful assistance in confirming or refuting them. Here is an email response from Roy, W7EL, when I used EZNEC to disprove his invalid coil current measurements. He apparently didn't like the EZNEC results from this file: http://www.w5dxp.ez/coil512.EZ Roy Lewallen wrote on May 12, 2007: I resent your trying to use EZNEC support as a surreptitious way to continue pushing your junk science on me. If you send me one more non-support related email, I'll put you on my spam list so your messages won't even make it to my ISP and I won't have to waste any more of my time on you. That'll mean no more EZNEC support, and I'll refund your EZNEC purchase price. So go ahead, send me one more non-support email and make an easy $149.00. Roy previously posted my private email without my permission so turn about is fair play. -- 73, Cecil http://www.w5dxp.com |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|