sdanie...@ wrote:

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
---------------------------
That depends....

An active antenna mounted on a small metal mast, or even a Rohn 25
TV style tower will experience minimal effect from the mast.
But mounted down near aluminium siding, or near a metal awning, near
metal roof will experience some effect. Well grounded metal should be
OK. But metal that is more or less floating, like aluminium siding,
will pick
up noise(any unwanted signal) and reradiate it into the antenna.

The best rule of thumb is far from any lines, electric, telephone, or
cable.
Even being over conductive pipes like water or NG can introduce noise.
I have my Amrad mounted up high on a shingled roof with a rat wire,
AKA hardware cloth, ground underneath. Works great.

Same thing for loop antennas or even wire antennas.

High and clear is the best.

Some may swear the "Snake" antenna is a "great thing". While I guess
it may have a place, it is about as far from a acceptable antenna as I
can think of.

High and clear.

With a good ground.

If I had to choose between a less then ideal antenna, say ~30'
unmatched
direct feed without coax with a good ground, and a great antenna with a

"so so" ground, I would go with the marginal antenna and good ground.

Even with a great active antenna like the AmRad, you still need the
best
ground you can get. Improving your ground will give a better return for
your time and money then anything else.

Terry