Microwave

Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter; with frequencies between 300 MHz (1 m) and 300 GHz (1 mm). Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF (millimeter wave) bands. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz (wavelengths between 0.3 m and 3 mm). In all cases, microwaves include the entire SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum. Frequencies in the microwave range are often referred to by their IEEE radar band designations: S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations.

History

The discovery of microwaves can be traced back to the 19th century when James Clerk Maxwell presented his theory of electromagnetic radiation in 1864. However, it was not until the 1940s that the technology was developed for practical use, primarily for radar systems during World War II.

Applications

Microwaves have a wide range of applications including communication, radar, and heating. In communication, they are used in television and radio broadcasting, cell phones, and satellite communication. In radar, they are used to detect objects and measure their distance, speed, and other characteristics. In heating, they are most commonly used in microwave ovens to heat food.

Health effects

Exposure to microwaves can have harmful effects on human health. These include burns, cataracts, and some temporary sterility. However, these effects are usually caused by exposure to high levels of microwaves, and the levels found in typical household appliances are generally considered safe.

See also

• Electromagnetic spectrum
• Radio waves
• Infrared

References

Microwave Resources
Latest articles Most recent articles Ongoing trials	Wikipedia