Radio Regulations
Source: the Radio Regulations published by the International Telecommunication Union (ITU).
1.8
WRC-27 · Agenda item 1.8
to consider possible additional spectrum allocations to the radiolocation service on a primary basis in the frequency range 231.5-275 GHz and possible new identifications for radiolocation service applications in frequency bands within the frequency range 275-700 GHz for millimetric and sub-millimetric wave imaging systems, in accordance with Resolution 663 (Rev.WRC-23)
Executive summary
Agenda item 1.8 asks WRC-27 to consider a new primary radiolocation (radar) allocation at 231.5–275 GHz and to identify bands for radiolocation applications across 275–700 GHz for millimetre- and sub-millimetre-wave imaging, under Resolution 663 (Rev.WRC-23).
These sub-terahertz frequencies enable stand-off detection of concealed objects for security and high-resolution imaging for transport safety — but the same region is where satellites and radio telescopes make passive measurements of the atmosphere and the universe, so the core question is whether active radar and passive science can coexist there.
Background
Above about 100 GHz the spectrum is largely the domain of passive science: Earth-exploration satellites sense atmospheric gases and radio astronomers observe molecular lines at specific frequencies. Across 275–1000 GHz the passive-service bands are identified by RR No. 5.565, and No. 5.564A identifies 275–450 GHz for fixed and land-mobile use under conditions protecting EESS (passive) at 296–306, 313–318 and 333–356 GHz and radio astronomy.
New sub-terahertz radar — security scanners and short-range imaging — would put active transmitters into or beside these bands. Resolution 663 opened the study to find where radar can be accommodated without compromising the passive measurements, which by their nature cannot tolerate interference.
Source: ITU Radio Regulations, editions of 2008, 2012, 2016, 2020 and 2024. The English, French and Spanish texts are each taken from the official edition in that language, not translated from one another. Sources and citation.