Microwaves And Power
The ability to focus microwave signals into narrow beams results in very high antenna gain. Antenna gain increases the effective-radiated power of a microwave signal much as the reflector in a flashlight produces a tight beam of light powerful enough to illuminate distant objects. The most common microwave-antenna focuses the signal by reflecting it from a parabolically-curved reflecting surface sometimes called a dish.
High antenna gain means that microwave transmitters need not be extremely powerful to produce a strong signal. A transmitter rated at 10 watts or less, using an antenna that concentrates the signal toward its target, can produce a received signal as strong as if thousands of watts were scattered in all directions.
Science EncyclopediaScience & Philosophy: Methane to Molecular clockMicrowave Communication - Microwaves And Power, Spatial Diversity, Microwave Propagation, Microwave Path Loss - Microwave transmitters, Satellites and microwaves