Pawsey stub velocity

I've been mucking about with a design which includes a Pawsey stub.
Some sources say the velocity factor of the feeder co-ax and the
quarter-wave shorting stub, which is made of co-ax with the inner
disconnected, must be taken into account.  Other sources say that the
velocity factor is that of an open wire, not co-ax, because the stub is
only the braid acting as a piece of wire.

I can see that the stub does not need to be treated as co-ax, because it
is just acting as wire (and the fact that it is made from the braiding
of co-ax is irrelevant).  I can also see that the feeder co-ax
apparently *is* being  used as co-ax which means its velocity factor
should be taken into account.  This leads to the logical conclusion that
the length of feeder co-ax shorted by the stub needs to be a different
length from the length of the stub itself - which none of the
descriptions mentions or illustrates (the kinks would be obvious).

The only possible explanation I can think of is that the current in the
braid of the shorted section of the feeder is cancelled by the current
in the stub, so that section of the feeder is not acting as co-ax and
the velocity factor doea not apply to it.  Nowhere can I find anything
which says that  - so it there another explanation?


--
~ Liz Tuddenham ~
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www.poppyrecords.co.uk