On Sun, 02 Mar 97 11:39:00 PST Cecil A Moore
<Cecil_A_Moore@ccm.ch.intel.com> writes:
> If your
>resonant half-wave dipole is fed with a natural
>number of half-wavelengths of coax, most of the
>RF will flow back down the outside of the coax braid
>instead of into the other half of the dipole.
Ooops, Sorry Cecil,
..
Any integer-multiple of half-wavelengths of coax feedline will appear
to be a HIGH impedance, and it WILL NOT radiate. A half-wave-length
coax feedline will not radiate. Assuming you have it attached to the
middle of a resonant dipole.
I believe you were trying to say that any ODD multiple of a
QUARTER-wavelength of coax will act as a nice second leg to your dipole,
and will radiate a goodly portion of your signal. And it will radiate a
significant portion if it is within about 33% of a quarter wavelength (or
multiple thereof) (I checked using EZNEC).
But of course he's right about the current balun, and using tv
ribbon line. My only hesitancy about balanced line is that here in
the Great Pacific Northwest you are likely to have moisture on that line
about half the time, either from rain or dew. Or worse. I don't
know what that does to the transmission characteristics of TV twinlead.
I am sure it lowers it's Zo, and that's not a real concern (you can
re-tune), but I suspect that muddy water (there's always dirt on the
line unless you're in one hell of a downpour!) increases the losses
substantially. Anybody out there got any data on this?
73, ; D DWink@Juno.com Dan Winkler N7IVR Seattle, WA
----------whom the gods would destroy, they first make proud ----------
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