1. The sole advantage of lasers is that they
permit narrow beamwidths to be realized with small transmitting mirrors, but this
advantage turns into a disadvantage at the receiver where we need a large collecting area.
2.The collecting surface is much cheaper and more
durable in the microwave region, because the tolerances are much greater and polished
surfaces are not needed.
3.Microwave systems offer substantially more range for
the same power, even with wider beamwidths.
4.Because of the wider beams, automatic positioning and
tracking are feasible at microwaves on a dead reckoning basis.
5.Doppler shifts and drift rates are orders of magnitude
less at microwave frequencies and can easily be compensated.
6.Microwave systems are all-weather systems.
