On Sun, 2008-07-06 at 20:04 -0700, Jim Brown K9YC wrote:
> On Sun, 06 Jul 2008 20:51:56 -0600, Dr. Gerald N. Johnson wrote:
>
> >NO! Coax does not radiate other than shield leakage, no matter what the
> >SWR.
>
> Yes and no. Radiation from coax is NOT related to VSWR. Radiation from ANY
> feedline, including coax, is DIRECTLY related to IMBALANCE in the antenna
> with
> respect to the reference plane (ground for earth stations).
>
> 73,
>
> Jim Brown K9YC
>
>
But the original premise was that coax radiated with high SWR, and
didn't state the high SWR (and possibility of unbalance) was from being
connected to an antenna. That high SWR coax could be between exciter and
PA (on different bands) and if both boxes are shielded, there is no
antenna unbalance to put RF on the outside of the coax, hence the coax
shielding minimizes radiation. Belden coax does a better job than RS
coax, and double shielded coax does even better, nearly as good as solid
shield CATV cable and Andrew Heliax.
73, Jerry, K0CQ
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