I was reading the instructions that came with an LF Engineering H-800
active antenna earlier today. They caution against mounting the antenna
in the vicinity of metal objects. At the same time, they say it's fine
to mount the antenna on a metal mast. What's the explanation of this?
If metal objects will interfere with reception, why doesn't this hold
true of metal masts?

And more generally, I'm curious about the extent to which relatively
small metal objects interfere with reception. In my (admittedly
limited) experience, so long as an outdoor antenna is at least a few
feet away from metal objects (e.g., gutters, ventilation pipes, etc.),
their effects on reception are minimal. Is this correct? I don't know
the physics, and other may have had experiences that differ from mine.
So you tell me: Are metal objects bigger problems than I think?

Steve