what are radomes ?

Lots of manufacturer info on the net. Here's some. Need any more?
http://www.radome.net/

These are protective coverings for antennas that do not hinder the antenna operation. They were first used in RADAR applications and the name is the contraction of RADAR and dome. They protected the parabolic reflector antennas from the effects of wind (mechanical forces) and weather (Ice on the reflector changed the radiation pattern).

Since the radomes protected the reflectors on ice etc. so theres no need to put heaters or blowers.

On the other hand, radomes are relatively expensive and they do increase noise.

Practical simulations of antenna and radomes by Hirsch etal by Artech House
this book can anybidy help