"Dennis O'Connor" wrote in message
...
Larger is better, however... Look at the dish at Arecibo for example..
http://www.rainforestsafari.com/observe.html

Radio antennae such as that one use reflection, not refraction, to focus
radio waves. In fact, I'm not aware of a single refractor radio antenna.

Similarily, a camera lens that works efficiently at lower light levels
will
be larger in diameter for a given focal length than one that doesn't work
as
efficiently... i.e., an f:2.8 lens versus an f:1.4 lens..

Larger optical lenses are "faster" (i.e. lower f- number) because they
gather more light. It has nothing to do with wavelengths.

Pete