What is Microwave radiation: Definition and 23 Discussions

Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. 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.
The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range. Rather, it indicates that microwaves are "small" (having shorter wavelengths), compared to the radio waves used prior to microwave technology. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study.
Microwaves travel by line-of-sight; unlike lower frequency radio waves they do not diffract around hills, follow the earth's surface as ground waves, or reflect from the ionosphere, so terrestrial microwave communication links are limited by the visual horizon to about 40 miles (64 km). At the high end of the band, they are absorbed by gases in the atmosphere, limiting practical communication distances to around a kilometer. Microwaves are widely used in modern technology, for example in point-to-point communication links, wireless networks, microwave radio relay networks, radar, satellite and spacecraft communication, medical diathermy and cancer treatment, remote sensing, radio astronomy, particle accelerators, spectroscopy, industrial heating, collision avoidance systems, garage door openers and keyless entry systems, and for cooking food in microwave ovens.

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  1. C

    Measuring wavelength of microwave radiation using double slits

    For this problem, The solution is, However, when they found the angle, they did not account for the uncertainty. I guess this is allowed still since the sine of the angle will still be greater than 1, correct? Many thanks!
  2. maayan_aloni

    I Exploring Oscillating Electric Fields for Dipolar Molecules

    Hi all! I was wondering, Is it possible, given a specific dipolar molecule, to create the perfect oscillating electric field so as to heat it and not, i.e. the water around it? What I'm basically asking is could there exist a specific microwave just for X and not all dipolar molecules without...
  3. Narayanan KR

    A Different Way to Achieve Electron Velocity Modulation in a Klystron

    Please Notice That the Toroid Coil is Outside the Discharge Tube and yet able to influence electrons moving inside the Tube.
  4. E

    Different metals and their compounds' reaction to Microwaves

    Does anyone know of any studies into exactly how much various metals reflect or absorb microwaves with relationship to the microwaves wavelength and ideally theyt compounds too?
  5. T

    How many energy requires to increase 1℃ of 1 liter of water using MICROWAVE?

    we planning to heat water directly using microwave for industrial purpose. we need only 33deg Celsius for that I need this.
  6. T

    I Why hasn't the light from the CMB already passed us?

    If the cosmic microwave background occurred at the moment that electrons and protons joined together and photons were now free to travel across the universe, then why haven't those photons already passed it. I'm having a hard time understanding why we can see the CMB forever if it was simply a...
  7. M

    Why Is the Calculated Temperature of the Universe Different from 3K?

    Homework Statement Two scientists detected the cosmic microwave background radiation at a frequency of 160 GHz. What is the temperature of the universe? Homework Equations peak wavelength x temperature = 2.898 x 10^-3 c = f x wavelength The Attempt at a Solution I calculated the wavelength of...
  8. V

    Microwave's vent close to refrigerator

    < Mentor Note -- Post edited > 1. Homework Statement So do you know how a microwave has air vents on the side? How much of a distance must be allowed between the vent and the side of refrigerator in order for the Microwave not to overheat? Is 10 cm enough? Would putting an aluminum foil on...
  9. F

    Why do people worry so much about microwave radiation?

    Why do people worry so much about microwave radiation if it has less energy than infrared (heat) radiation? Why do they worry about STANDING near microwaves versus standing near heat sources? Why do they worry about using it to heat up their food if it's lower in energy than infrared?
  10. E

    How would you convert visible light to infrared or microwave

    Is it possible to convert light in the visible spectrum to infrared or microwave light. What processes would be used to do this? Thanks, EJ
  11. adoion

    Explaining the Big Bang: The Science Behind the Universe's Rapid Expansion

    hi, 1. radiation travels faster than matter. 2. our Earth was formed much after the big bang. The big bang goes like this. At some point in time and in some point in space (witch we cannot determent so we just leave the location open and say it could have happened anywhere) all the matter...
  12. S

    Infrared wave cooking vs microwave radiation

    I have learned that penetration ability increases with frequency. But why can microwave cook faster than infrared wave? Infrared gas a greater frequency so it should penetrate more and thus cook faster. So I'm not so clear about this. Thanks for the help
  13. L

    Where to find Microwave Radiation?

    I am a high school student and i am doing a science fair project about radiation. i have a microwave detector and i would like to know where i can find microwave length radiation so i can test and record results. I have tested microwaves and cell phones but i can't think of anything else. What...
  14. S

    Can microwave radiation penetrates building materials?

    Can Microwave radiation penetrates building materials? I'm living within 120 meters from a mobile phone base station and I'm concerned with possible health effects from it .
  15. S

    Quick question about Microwave radiation

    I read in a book that: Microwaves are considered lower in energy than infrared waves because they do not affect all molecules, only the polar ones. Polar molecules have slightly different electrical charges at their opposite ends, making them more responsive to microwave radiation than...
  16. D

    Milky Way excess Microwave Radiation

    Could some of the cosmic background radiation be produced within the fabric of space itself? What if the big bang was not a one of event 15billion years ago but is happening right now today, now, all around us within the quantum world? If indeed the CBr was occurring within the fabric of...
  17. N

    How does cosmic microwave radiation lose energy?

    Can anyone explain how the cosmic microwave background radiation (CMBR) "cooled"...I'm supposing that about 300,000 years or so after the bang, when the universe became transparent, things were hotter than 2.7 degrees above absolute zero we observe today... Wikipedia says: So an expanding...
  18. S

    Microwave Radiation: Is Standing Nearby Harmful?

    Can standing in front of a microwave actually cause you harm?
  19. C

    Does microwave radiation linger inside a microwave oven?

    I was curious about microwave ovens and how they work and in particular about the microwave radiation they emit and the halflife of this radiation. My layman's understanding is that microwave ovens use a 2.43GHZ emf to heat up water inside food items by attenuating 1 or more? of the few...
  20. V

    Detecting a stars microwave radiation intensity

    Homework Statement A microwave detector is located 0.5m above the surface of a large lake far from the shore. As a star, emitting monochromatic microwave radiation of 21cm wavelength, rises slowly above the horizon, the detector indicates successive maxima and minima in the signal intensity...
  21. B

    Microwave radiation proves what?

    Ok, so as I understand it microwave radiation can be detected from 'outer space' but what does that prove? I really don't see why it should be evidence of a big bang, absolutely none whatsoever, infact microwaves would probably one of the last things on my list as evidence. What is the...
  22. M

    Why do metal objects behave violently in microwave radiation?

    I'm not really sure where this question goes. I was wondering why metal behaves so violently when exposed to microwave radiation. For example if you put a metal object into a microwave, it sparks and if there are things attached such as plastic tops will explode off of what ever is in it. What...
  23. S

    Early background microwave radiation question.

    Why hasn’t the background microwave radiation from the early universe all burnt out by now? (Penzias, Wilson, Dicke, Peebles, and George Gamow’s discovery of background radiation is what I am referring to.) I’ve heard a couple reasons on what caused the radiation… One about antimatter and...