Microwaves, like light rays, are a type of electromagnetic radiation. In the electromagnetic spectrum, they fall somewhere between radio waves and infrared rays. Generally, they have wavelengths ranging from 0.039 in. (1 mm) to 1.6 in. (40 cm).

Microwave technology was developed during World War II in connection with secret military radar research. Today, microwaves are primarily used in communications. Several devices can be used to generate microwaves, the most popular being magnetrons and klystrons. Most produce microwaves of relatively low power and require the use of an amplification device, such as a maser (microwave amplification by stimulated emission of radiation). Like radio waves, microwaves can be modulated for communication purposes; they are more versatile than radio waves, however, and are often used in setting up communication networks and radio relay systems. Although microwaves can be easily broadcast and received via aerial antennas, their high frequency nature makes it difficult...