My Satellite antenna, It arrived, now I've gotta install it

[Jerry Liebler]

KT,
   The problem with adding something over the dish is due to 'refraction'.  The speed of propagation of electromagnetic radiation through any material is the speed of light in that material.  Light travels through different materials at different speeds, it is fastest in a vacuum. If a ray, of electromagnetic radiation hits a surface,of a  material which is different than it has been traveling in, at any angle that's not perpendicular it's direction and speed are changed. While if it hit's the 'interface' perpendicularly only it's speed is changed.  Diffraction is why lenses work, they can bend parallel waves so they all land on a point, this is called focusing the parallel rays.  The antenna is trying to collect parallel rays but by putting something over it they aren't parallel anymore.  The radome around many dishes is carefully designed as another lens in the antenna's focusing plan.  But if the material added has propagation characteristics close to air, is thin relative to the wavelengths and is of good uniformity the results may be acceptable.
Hope this helps.
Regards
Jerry 407 1120

[JohnEd]

KT,

Its complicated.  The thickness of the fiberglass is a multiple of the wavelength of the RF you want to pass through it so the glass doesn't attenuate the signal.  The dome is no exception and to keep that "apparant" thickness constant the rf passes through the dome with the planes at right angles to each other.  Same thickness whichever way the antenns is pointed.  If you place it under a "sheet" the amt of glass the signal passes throuigh will be much larger at low angles of elevation that at high.

This may not be clear.  Sorry if it isn't.

John

[JohnEd]

Jerry,

Better app of your situation now.  Your design seems great, anyway. 

Good luck,

John