Microwaves are electromagnetic waves in the frequency range 300 MHz to 30 GHz. Electromagnetic waves above 30 GHz are called millimetre waves and those under 300 MHz are high frequency. Light is also electromagnetic waves, however of a much higher frequency (1.7 THz), and can be seen by the human eye. Light therefore has the same diffusion characteristics as microwaves.
throughout the overall frequency range for the transmission of signals such as radio signals, television pictures, telephone conversations, etc.
for radar technology:
for the recognition and tracking of aircraft in the sky or of vessels on the sea (spectroscopy).
in the kitchen:
at 2.45 GHz for the warming of food. The movement of molecules in the alternating field causes frictional heat.
for process engineering:
mainly continuous systems are used at 2.45 GHz, to warm products for drying, sterilization, evaporation and cooking purposes.
for sensor engineering:
mainly at 2.45 GHz, 5.8 GHz and 24.125 GHz, to recognize movement, measure speed and to measure or monitor product characteristics, i.e. moisture measurement.