Joey wrote:
Our vacation house has about 75 of plastic rain gutters on 3 sides of
the flat roof at about 20 feet up (2 story). I was thinking about
laying a 40m dipole in there with no connection to anything on the
house. The only question I have is, is that there is a 2" strip of
metal flashing about 8 inches above the gutter, for the length of it.
How bad do you think this would screw up a dipole that's essentially
parallel to it?

It will act somewhat like guy wires which can cause
distortion in the radiation pattern and losses.
With any luck, it will have a high impedance and
not have much effect. Try it and see what happens.
Worst case, you may need to cut a slit every 1/4 WL
to keep the currents low.
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73, Cecil http://www.w5dxp.com