From the nimble fingers of tedd (tedd@...) (18/1/2002 9:10 AM)
came...

>>> So, you could look at this like the intersection of two spheres. The
>>> circle of reception would be the locus of all points common to the
>>> surfaces of both spheres.

That (intersection) would, of course, be a circle; you might be more
interested in the area enclosed within the circle...

> 1. Unless the satellite is actually "on the fly" redirecting it's
> parabolic dish (which I don't think it does), then the "footprint"

Geosync broadcasting satellites don't usually redirect their antennae, but
they don't illuminate the visible sphere, either. They now have truly
monumental dishes (in the 100 m diameter range), and can lay up a beam with
half-power points spaced well under 1 degree. Also, a single such dish will
typically have several feedhorns, and will cover their intended target (a
continent, for example) with 5 or more distinct signals, physically and
accurately separated.


-- 
Ted Spencer; ted@...
--
Time is Nature's way of keeping everything from happening at once.