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#1
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..5l II .5l II .5L II .5l can't ell from the drawings I find hi the stub 1.4 wave each are terminated at the end and thus the outer end fed by induction or shorted togather at the botom (most likely IMO) or shorted at the top I suppose is possible sorry folks just not quite making out the drawing of of this for that detail Help is asked some abuse is expected (please feel free to disapoint) |
#2
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what hel pdo you need? i dont see a question? mark
nevermind i don't think i could help but someone else sure needs a ? mark On May 10, 3:36 pm, an_old_friend wrote: ----------- ---------- -------- ---------- .5l II .5l II .5L II .5l can't ell from the drawings I find hi the stub 1.4 wave each are terminated at the end and thus the outer end fed by induction or shorted togather at the botom (most likely IMO) or shorted at the top I suppose is possible sorry folks just not quite making out the drawing of of this for that detail Help is asked some abuse is expected (please feel free to disapoint) |
#3
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On May 10, 3:36 pm, an_old_friend wrote:
----------- ---------- -------- ---------- .5l II .5l II .5L II .5l can't ell from the drawings I find hi the stub 1.4 wave each are terminated at the end and thus the outer end fed by induction or shorted togather at the botom (most likely IMO) or shorted at the top I suppose is possible sorry folks just not quite making out the drawing of of this for that detail Help is asked some abuse is expected (please feel free to disapoint) Normally, the stubs are 1/4 wave long (resonant at the operating frequency), shorted at the end away from the antenna so they look like a very high resistance at the antenna. Proper operation depends on the stub's coupling to the antenna field, so for example, it doesn't work well to make the stub a piece of coax that's part of the linear antenna. This also is the beginning of an explanation why you need the stub at all, and can't just put a gap between the ends of the elements. (After all, if the stub reflects an open back to where it connects to the antenna elements, why can't it be just omitted?) On the other hand, a properly constructed "coaxial collinear," where the coax is actually driven, can work quite well--but the lengths of the radiating sections are shortened. Hope I haven't disappointed you too much by not giving you the expected abuse... Cheers, Tom |
#4
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ok 1/4 stubs and not 1.4 stubs
On May 11, 12:50 pm, K7ITM wrote: On May 10, 3:36 pm, an_old_friend wrote: ----------- ---------- -------- ---------- .5l II .5l II .5L II .5l can't ell from the drawings I find hi the stub 1.4 wave each are terminated at the end and thus the outer end fed by induction or shorted togather at the botom (most likely IMO) or shorted at the top I suppose is possible sorry folks just not quite making out the drawing of of this for that detail Help is asked some abuse is expected (please feel free to disapoint) Normally, the stubs are 1/4 wave long (resonant at the operating frequency), shorted at the end away from the antenna so they look like a very high resistance at the antenna. Proper operation depends on the stub's coupling to the antenna field, so for example, it doesn't work well to make the stub a piece of coax that's part of the linear antenna. This also is the beginning of an explanation why you need the stub at all, and can't just put a gap between the ends of the elements. (After all, if the stub reflects an open back to where it connects to the antenna elements, why can't it be just omitted?) On the other hand, a properly constructed "coaxial collinear," where the coax is actually driven, can work quite well--but the lengths of the radiating sections are shortened. Hope I haven't disappointed you too much by not giving you the expected abuse... Cheers, Tom |
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