Science, Tech, Math › Science Microwave Radiation Definition Share Flipboard Email Print Granville Davies / Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 12, 2021 Microwave radiation is a type of electromagnetic radiation. The prefix "micro-" in microwaves doesn't mean microwaves have micrometer wavelengths, but rather that microwaves have very small wavelengths compared with traditional radio waves (1 mm to 100,000 km wavelengths). In the electromagnetic spectrum, microwaves fall between infrared radiation and radio waves. Frequencies Microwave radiation has a frequency between 300 MHz and 300 GHz (1 GHz to 100 GHz in radio engineering) or a wavelength ranging from 0.1 cm to 100 cm. The range includes the SHF (super high frequency), UHF (ultra high frequency) and EHF (extremely high frequency or millimeter waves) radio bands. While lower frequency radio waves can follow the contours of the Earth and bounce off layers in the atmosphere, microwaves only travel line-of-sight, typically limited to 30-40 miles on the Earth's surface. Another important property of microwave radiation is that it's absorbed by moisture. A phenomenon called rain fade occurs at the high end of the microwave band. Past 100 GHz, other gases in the atmosphere absorb the energy, making air opaque in the microwave range, although transparent in the visible and infrared region. Band Designations Because microwave radiation encompasses such a broad wavelength/frequency range, it is subdivided into IEEE, NATO, EU or other radar band designations: Band Designation Frequency Wavelength Uses L band 1 to 2 GHz 15 to 30 cm amateur radio, mobile phones, GPS, telemetry S band 2 to 4 GHz 7.5 to 15 cm radio astronomy, weather radar, microwave ovens, Bluetooth, some communication satellites, amateur radio, cell phones C band 4 to 8 GHz 3.75 to 7.5 cm long-distance radio X band 8 to 12 GHz 25 to 37.5 mm satellite communications, terrestrial broadband, space communications, amateur radio, spectroscopy Ku band 12 to 18 GHz 16.7 to 25 mm satellite communications, spectroscopy K band 18 to 26.5 GHz 11.3 to 16.7 mm satellite communications, spectroscopy, automotive radar, astronomy Ka band 26.5 to 40 GHz 5.0 to 11.3 mm satellite communications, spectroscopy Q band 33 to 50 GHz 6.0 to 9.0 mm automotive radar, molecular rotational spectroscopy, terrestrial microwave communication, radio astronomy, satellite communications U band 40 to 60 GHz 5.0 to 7.5 mm V band 50 to 75 GHz 4.0 to 6.0 mm molecular rotational spectroscopy, millimeter wave research W band 75 to 100 GHz 2.7 to 4.0 mm radar targeting and tracking, automotive radar, satellite communication F band 90 to 140 GHz 2.1 to 3.3 mm SHF, radio astronomy, most radars, satellite tv, wireless LAN D band 110 to 170 GHz 1.8 to 2.7 mm EHF, microwave relays, energy weapons, millimeter wave scanners, remote sensing, amateur radio, radio astronomy Uses Microwaves are used primarily for communications, include analog and digital voice, data, and video transmissions. They are also used for radar (RAdio Detection and Ranging) for weather tracking, radar speed guns, and air traffic control. Radio telescopes use large dish antennas to determine distances, map surfaces, and study radio signatures from planets, nebulas, stars, and galaxies. Microwaves are used to transmit thermal energy to heat food and other materials. Sources Cosmic microwave background radiation is a natural source of microwaves. The radiation is studied to help scientists understand the Big Bang. Stars, including the Sun, are natural microwave sources. Under the right conditions, atoms and molecules can emit microwaves. Man-made sources of microwaves include microwave ovens, masers, circuits, communication transmission towers, and radar. Either solid state devices or special vacuum tubes may be used to produce microwaves. Examples of solid-state devices include masers (essentially lasers where the light is in the microwave range), Gunn diodes, field-effect transistors, and IMPATT diodes. The vacuum tube generators use electromagnetic fields to direct electrons in a density-modulated mode, where groups of electrons pass through the device rather than a stream. These devices include the klystron, gyrotron, and magnetron. Reference Andjus, R.K.; Lovelock, J.E. (1955). "Reanimation of rats from body temperatures between 0 and 1 °C by microwave diathermy". The Journal of Physiology. 128 (3): 541–546. Cite this Article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "Microwave Radiation Definition." ThoughtCo, Aug. 12, 2021, thoughtco.com/microwave-radiation-definition-4145800. Helmenstine, Anne Marie, Ph.D. (2021, August 12). Microwave Radiation Definition. Retrieved from https://www.thoughtco.com/microwave-radiation-definition-4145800 Helmenstine, Anne Marie, Ph.D. "Microwave Radiation Definition." ThoughtCo. https://www.thoughtco.com/microwave-radiation-definition-4145800 (accessed October 22, 2021). copy citation Microwave Astronomy Helps Astronomers Explore the Cosmos Radiation in Space Gives Clues about the Universe Electromagnetic Radiation Definition How Radio Waves Help Us Understand the Universe Gamma Radiation Definition Learn about the Doppler Effect The History of the X-Ray Visible Light Definition and Wavelengths What Is Blackbody Radiation? Examples of Radiation (and What's Not Radiation) Gamma Rays: The Strongest Radiation in the Universe Spectroscopy Definition When Was the First TV Invented? Can a Planet Make a Sound in Space? Radiation Definition and Examples Can Humans Hear Sound in Space?