On May 10, 3:36 pm, an_old_friend wrote:
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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)


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