[TowerTalk] ant

[Jim Lux]

I assume you mean 148 MHz and 2 meter band, not a 2 meter diameter dish?

To get any sort of reasonable gain you're looking at a fairly large dish (10
meters in diameter, perhaps?)
At least for this frequency the surface tolerance isn't going to be all that
tight... say, 10 cm (4").  You can also make it out of something fairly
"airy" so that you don't build up snow. Something like 4" reinforcing mesh
might work quite nicely.  A stressed skin kind of idea with a hexagonal grid
might also work.  For spherical, the various geodesic things are a good way
to go.  You build a mold or jig to make panels of a reasonable size (say a
meter on a side) and then bolt them up (or glue or weld) to form the entire
dish.

Are you sure you need spherical surface and not parabolic?  Are you moving
the feed to point the beam?

What sort of f/d do you need (or, more relevant to a spherical reflector,
how far is the feed from the dish (what radius).

On the other hand, if you're looking for 148 GHz and a 2 meter diameter
aperture, you've got a huge engineering problem in front of you.

----- Original Message -----
From: <Darfug at aol.com>
To: <towertalk at contesting.com>
Sent: Sunday, August 24, 2003 1:35 PM
Subject: [TowerTalk] ant


> I need spherical,and one piece.I get alot of snow and Ice.the feed I would
> rather a simple design,because of weather. I may move it down the tower
if
> weather gets bad.And freq around 148.