Hi,

Real newbie regarding antenna theory, but am trying to learn.
Have ordered the ARRL antenna book.

a. In my attic, right next to each other, I have a Scantenna and a Discone
antenna.
Both have the same coax run to my study downstairs. Don't remember the type
of coax, but it's the large diameter, "low loss" type for both.

The Scantenna feeds a new Uniden BCD996 Scanner.
The Discone feeds my JRC NRD 545 (with the VHF converter board).

When tuned to the Coast Guard station (156.8 MHz fm) about 25 miles away
(way beyond my line of sight, but they probably have a high tower) the 545
with the Disconne is vastly superior.

Of course the 545 is a much, much better radio than the the Uniden, but I
assumed that for this type of listening configuration, reception would be
mainly limited by the antenna ?

I also thought that the Discone would be most effective for aero., and very
minimally effective for more or less horizontal signal paths like from the
Coast Guard Tower to me.

Any thoughts on this, and on Discones (for "horiz." propagated signals) in
general ?

b. Never thought about this before, but have started wondering.
Might be a good question for all you experts out there.

Live in a typical New England Colonial with a plastic Louvre in the attic on
each gable end that are screened to keep the bugs out.
Screens are metal.

As mentioned, in the attic I have two VHF antennas, the Scantenna and a
Discone.
(do listening only)

Was wondering if the metal screens might have any effect on what I can pick
up in the more or less horizontal directions ?
e.g., P.D.'s from our or a neighboring town, and the Coast Guard station.

Probably have no effect for aero comm listening as these received signals
are pretty much from a vertical, or near vertical direction.

Should I go to the trouble of replacing them with plastic screens ?

Distance from antennas to the screens is probably about 20 feet or so.
This subtends a relatively small angle, but not that small. Haven't
measured the screen, but assume about the size of a typical house bedroom
window.

Any thoughts on this ?

As always, thanks,
Bob