Question

Suggest why signals to satellites are transmitted as slightly divergent beam and not as a parallel beam.

Answer 1

I can think of two reasons:

1).  EVERY transmitted radio signal is transmitted as
a divergent beam.  We don't have the technology to
transmit it as a perfectly parallel beam.
That's a good thing, because ...

2).  If it were a perfect pencil-thin parallel beam, then
it would be practically impossible to keep it perfectly
aimed at the satellite.