Extremely high frequency
the 30–300 GHz range of the electromagnetic spectrum
Extremely high frequency (EHF) is the electromagnetic band from 30 to 300 gigahertz (GHz), as designated by the International Telecommunication Union (ITU) designation. It is in the microwave part of the radio spectrum, between the super high frequency band and the terahertz band. Radio waves in this band have wavelengths from ten to one millimeter (10–1 mm), so it is also called the millimeter band and radiation in this band is called millimeter waves (sometimes abbreviated MMW or mmWave).
Some define mmWaves as starting at 24 GHz, thus covering the entire FR2 band (24.25 to 71 GHz), among others.
Compared to lower frequency bands, radio waves in this band have high atmospheric attenuation: they are absorbed by the gases in the atmosphere. Absorption increases with frequency until at the top end of the band the waves are attenuated to zero within a few meters. Absorption by humidity in the atmosphere is significant except in desert environments, and attenuation by rain (rain fade) is a serious problem even over short distances. However the short propagation range allows smaller frequency reuse distances than lower frequencies. The short wavelength allows modest size antennas to have a small beam width, further increasing frequency reuse potential. Millimeter waves are used for military fire-control radar, airport security scanners, short range wireless networks, and scientific research.
The public source identifies “Extremely high frequency” as the 30–300 GHz range of the electromagnetic spectrum. This brief keeps that definition visible, then builds a research path around Extremely, high and frequency.
Why this record matters
A short description can identify a subject without explaining its stakes. For “Extremely high frequency”, the useful work is to connect “the 30–300 GHz range of the electromagnetic spectrum” to the records capable of establishing context and consequence.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Aug 6, 2026. The linked authority identifier is Q570342. The Library of Congress control number is sh85085407. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank.
A concise general-reference account can conceal disagreements about scope, terminology or the weight assigned to individual sources. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Extremely high frequency”, its source revision and the description used here.
- Expand the search: follow Extremely high frequency primary sources, Extremely high frequency archive and Extremely research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Extremely high frequency”?
- What terminology or title could unlock a more precise catalogue search?
- Which institution is responsible for the underlying evidence?
Search terms from this dossier
This entry incorporates text from “Extremely high frequency” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.