Ian Jackson wrote in
:

In message , Owen Duffy
writes
....
End fed antennas are an implementation risk.

What's an 'implementation risk'?


We will see if the OP, like so many who implement J poles in the roof
space, becomes aware of problems and comes back for advice on how to
solve them.

The commonest problem is that VSWR doesn't meet expectations, but that it
is the most mentioned problem speaks more of the visibility of VSWR that
that it is the greatest problem with the J Pole.

Like many if not most end fed antennas, the J Pole does little to deal
with the common mode current that must flow on the feed system / support
structure. Explanations of how they work usually deny the issue.

But for all their faults, they spray RF around, and people would foolish
to deny that they 'work' to some extent.

When you look at the strengths and weaknesses of a J Pole, they are not a
good choice IMHO for in-roof-space deployment.

Owen