In message , George Cornelius
writes
Still, I would be curious as to whether that 50% rule - if it is
accurate at all (does a laser beam hitting a black body have to
reflect back 50%?) - applies to a microwave downlink.

If it's a true black body it's all absorbed , and either conducted away
as heat or re-radiated at the temperature of the black body at
different wavelengths

A better laser analogy is a set of lenses and a focussed fibre-optic
between them. It's possible to arrange this to be nearly 100% efficient.

Brian

--
Brian Howie