Editing Radio propagation (section)

==Frequency dependence==
At different frequencies, radio waves travel through the atmosphere by different mechanisms or modes:<ref name="Seybold">
{{cite book
 | last1  = Seybold  | first1 = John S. 
 | date   = 2005
 | title  = Introduction to RF Propagation
 | pages  = 3–10
 | publisher = John Wiley and Sons
 | language = 
 | url    = https://books.google.com/books?id=4LtmjGNwOPIC&pg=PA6
 | isbn   = 0471743682
}}
</ref>
{{clear}}
{| class="wikitable" style="margin:0.5em auto"
|+ Radio frequencies and their primary mode of propagation
|-
! colspan=2 | Band
! Frequency
! Wavelength
! Propagation via
|-
| [[Extremely low frequency|ELF]]
| Extremely Low Frequency
| 3–30 [[hertz|Hz]]
| 100,000–10,000&nbsp;km
| Guided between the Earth and the [[D layer]] of the ionosphere.
|-
| [[Super low frequency|SLF]]
| Super Low Frequency
| 30–300 [[hertz|Hz]]
| 10,000–1,000&nbsp;km
| Guided between the Earth and the [[ionosphere]].
|-
| [[Ultra low frequency|ULF]]
| Ultra Low Frequency
| 0.3–3&nbsp;[[kilohertz|kHz]]<br/>(300–3,000&nbsp;Hz)
| 1,000–100&nbsp;km
| Guided between the Earth and the [[ionosphere]].
|-
| [[Very low frequency|VLF]]
| Very Low Frequency
| 3–30&nbsp;[[kilohertz|kHz]]<br/>(3,000–30,000&nbsp;Hz)
| 100–10&nbsp;km
| Guided between the Earth and the [[ionosphere]].
[[Ground wave|Ground waves]].
|-
| [[Low frequency|LF]]
| Low Frequency
| 30–300&nbsp;[[kilohertz|kHz]]<br/>(30,000–300,000&nbsp;Hz)
| 10–1&nbsp;km
| Guided between the Earth and the ionosphere.
[[Ground wave|Ground waves]].
|-
| [[Medium frequency|MF]]
| Medium Frequency
| 300–3,000&nbsp;[[kilohertz|kHz]]<br/>(300,000–3,000,000&nbsp;Hz)
| 1000–100&nbsp;m
| [[Ground wave|Ground waves]].
E, [[F layer]] ionospheric refraction at night, when D layer absorption weakens.
|-
| [[High frequency|HF]]
| High Frequency ([[shortwave|Short Wave]])
| 3–30&nbsp;[[megahertz|MHz]]<br/>(3,000,000–30,000,000&nbsp;Hz)
| 100–10&nbsp;m
| [[E layer]] ionospheric refraction.
F1, [[F2 propagation|F2]] layer ionospheric refraction.
|-
| [[Very high frequency|VHF]]
| Very High Frequency
| 30–300&nbsp;[[megahertz|MHz]]<br/>(30,000,000–<br/>&nbsp; &nbsp; 300,000,000&nbsp;Hz)
| 10–1 m
| [[Line-of-sight propagation]]. 
Infrequent [[Sporadic E propagation|E ionospheric (E<sub>s</sub>) refraction]]. Uncommonly [[F2 propagation|F2]] layer ionospheric refraction during high sunspot activity up to 50&nbsp;MHz and rarely to 80&nbsp;MHz. Sometimes [[tropospheric ducting]] or [[Meteor burst communications|meteor scatter]]
|-
| [[Ultra high frequency|UHF]]
| Ultra High Frequency
| 300–3,000&nbsp;[[megahertz|MHz]]<br/>(300,000,000–<br/>&nbsp; &nbsp; 3,000,000,000&nbsp;Hz)
| 100–10&nbsp;cm
| [[Line-of-sight propagation]]. Sometimes [[tropospheric ducting]].
|-
| [[Super high frequency|SHF]]
| Super High Frequency
| 3–30 [[gigahertz|GHz]]<br/>(3,000,000,000–<br/>&nbsp; &nbsp; 30,000,000,000&nbsp;Hz)
| 10–1&nbsp;cm
| [[Line-of-sight propagation]]. Sometimes [[Radio propagation#Rain scattering|rain scatter]].
|-
| [[Extremely high frequency|EHF]]
| Extremely High Frequency
| 30–300&nbsp;[[gigahertz|GHz]]<br/>(30,000,000,000–<br/>&nbsp; &nbsp; 300,000,000,000&nbsp;Hz)
| 10–1&nbsp;mm
| [[Line-of-sight propagation]], limited by atmospheric absorption to a few kilometers (miles)
|-
| [[Tremendously high frequency|THF]]
| Tremendously High frequency
| 0.3–3&nbsp;[[Terahertz (unit)|THz]]<br/>(300,000,000,000–<br/>&nbsp; &nbsp; 3,000,000,000,000&nbsp;Hz)
| 1–0.1&nbsp;mm
| [[Line-of-sight propagation]], limited by atmospheric absorption to a few meters.<ref name=Coutaz>{{cite book
 | last1  = Coutaz  | first1 = Jean-Louis
 | last2  = Garet   | first2 = Frederic
 | last3  = Wallace | first3 = Vincent P.
 | year   = 2018
 | title  = Principles of Terahertz Time-Domain Spectroscopy: An introductory textbook
 | publisher = CRC Press  |place = Boca Raton, FL
 | page   = 18
 | isbn   = 9781351356367
 | url    = https://books.google.com/books?id=zah8DwAAQBAJ&pg=PA18
}}
</ref><ref name=Siegel>
{{cite web
  | last = Siegel | first = Peter
  | year = 2002
  | title = Studying the Energy of the Universe
  | series = Education materials
  | website = [[National Aeronautics and Space Administration]] (nasa.gov)
  | url = https://www.nasa.gov/audience/foreducators/k-4/features/Peter_Siegel.html
  | access-date = 19 May 2021
}}
</ref>
|- style="background-color:lightgrey;"
| [[Far infrared|FIR]]
| Far infrared light<br/>(overlaps radio)
| 0.3–20&nbsp;[[Terahertz (unit)|THz]]<br/>(300,000,000,000–<br/>&nbsp; &nbsp; 20,000,000,000,000&nbsp;Hz)
| 1,000–150&nbsp;μm<ref name=Byrnes>
{{cite book
  |last=Byrnes |first=James
  |year=2009
  |title=Unexploded Ordnance Detection and Mitigation
  |publisher=Springer
  |isbn=978-1-4020-9252-7
  |pages=[https://archive.org/details/unexplodedordnan00abry/page/n29 21]–22
  |url=https://archive.org/details/unexplodedordnan00abry |url-access=limited
}}
</ref><ref name=Glagoleva>
{{cite journal
  |first=A. |last=Glagoleva-Arkadiewa |author-link=Alexandra Glagoleva-Arkadieva 
  |year=1924
  |title=Short electromagnetic waves of wave-length up to 82&nbsp;Microns
  |journal=[[Nature (journal)|Nature]]
  |volume=2844 |issue=113
  |doi=10.1038/113640a0
|doi-access=free}}
</ref><ref name=caltech>
{{cite web
  |title=Near, mid and far-infrared
  |series=Caltech Infrared Processing and Analysis Center
  |publisher=[[California Institute of Technology]]
  |url=http://www.ipac.caltech.edu/outreach/Edu/Regions/irregions.html
  |access-date=2013-01-28 |url-status=dead
  |archive-url=https://archive.today/20120529/http://www.ipac.caltech.edu/Outreach/Edu/Regions/irregions.html
  |archive-date=2012-05-29
}}
</ref>
| [[Line-of-sight propagation]], mostly limited by atmospheric absorption to a few meters.<ref name=Byrnes/><ref name=caltech/>
|}