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Re: "Trash Can" dish antennas

Ray - WB3ABN asked (in part):
> Most larger Navy and USCG ships have "trash can" antennas mounted on the
flying bridge.  The best way for me to describe them would be to take a
metal trash can, cut half of the top off, and mount the parabola in the
bottom with the feed in the open end.  This in effect is like wrapping a
"fence" around the outside edge of a normal circular dish.  Does this serve
to eliminate background noise from over illumination of the dish, so the
feed only sees signals from the front of the focal point?

That's one way to describe them.  Your last sentence is exactly right.  In
the terrestrial communications business, it's refered to as a high
performance dish.  The "fence" as you put it, reduces radiation (and
reception) in undesired directions.  You will see lots of them (only bigger
in most cases) at major communications sites.  Most of them have a covering
over the open end.  It is made of a canvas like material and is commonly
called a "tom-tom".

Jim Walls - K6CCC
Mobile Radio Operations
Southern California Edison Co.
Ofc:   626-302-8515   -   PAX   28-515
FAX:   626-302-7501   -   PAX   27-501

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