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#1
April 10th 04, 03:59 PM
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In article , Richard Clark
writes: On 9 Apr 2004 13:44:16 -0700, (N2EY) wrote: I get the feeling that Lattin either went through serious math pushups to get his design, or cut up a lot of Twin Lead, or both. Hi Jim, I am working on the design, however the premise appears to be "academic." In other words, there are some who can tell you how it should work, but not why it doesn't. I *like* that turn of phrase! "There are some who can tell you how it should work, but not why it doesn't." Perfect companion to: "If it happens, it must be possible." Your description above suits the modeling to a T - serious math pushups. Thanks. I don't think anyone could stumble onto a 5 band antenna by simple cut and try. I disagree! I think it not only could happen, but probably has happened already, through a fortuitous combination of many factors. But being able to come up with such a design that is well-documented and reproducible is a whole 'nother thing. The Lattin antenna is a perfect example of that. 73 de Jim, N2EY |
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#2
April 10th 04, 04:42 PM
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#3
April 10th 04, 06:51 PM
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In article , Richard Clark
writes: On 10 Apr 2004 14:59:24 GMT, PAMNO (N2EY) wrote: I don't think anyone could stumble onto a 5 band antenna by simple cut and try. I disagree! I think it not only could happen, but probably has happened already, through a fortuitous combination of many factors. Name one that works. And by works, is resonant in each band, and not simply tuneable (as would be a common doublet). Some forms of trap dipole and parallel dipole I have encountered were clearly the result of cut-and-try rather than analysis and mathematical design. But being able to come up with such a design that is well-documented and reproducible is a whole 'nother thing. The Lattin antenna is a perfect example of that. Hi Jim, The notion of a trapped antenna on the basis of resonant stubs constructions is not shown in the data of my work to date, and certainly not in the Lattin (insofar as the only interpretation generally available on the net, setting the patent aside that is). The title of the QST article (December, 1960) is "Multiband Antennas Using Decoupling Stubs". One of the key points goes to this notion of stub action. However, the stub is not excited across its mouth, but along its length. This is very distinctly exhibited in the numbers (the lack of correlation of stub geometry to resonances). The constructions merely appear to fatten a thin radiator and add capacitances and inductances that are basically opportunistic - certainly no one has shown any correlations that fit the geometries to the bands they are presumed to resonate to. Hence my statement that caught your fancy. The Stub resonances "should" explain the bands obtainable, and yet there has been absolutely no supporting evidence to demonstrate that this occurs. The claims of the QST article are that the stubs work as traps. It also explains that the velocity factor is important in the whole design. The article refers repeatedly to "tubular Twin Lead" as the optimum material for construction because of its velocity factor of 0.8. It does hold my interest, however, and I am hardly one to be put off by failure's of other's theories - not with my more than 300 pages of fractal data published in the face of fractal fools who confine themselves to bragging about their science. (grin) 73 de Jim, N2EY |
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