The 2.5-millimeteror122 GHz band is a portion of the EHF (microwave) radio spectrum internationally allocated to amateur radio use between 122.250 GHz and 123.000 GHz.[1]
Due to the lack of commercial off the shelf radios, amateurs who operate on the 2.5 mm band must design and construct their own equipment, and those who do, often attempt to set communication distance records for the band.
The International Telecommunication Union allocates 122.250 GHz and 123.000 GHz to amateur radio on a secondary basis. As secondary users, amateurs must protect the fixed, mobile and inter-satellite services from harmful interference, which share the band with amateurs. In addition, 122 GHz to 123 GHz is an ISM band, and all users must accept interference caused by ISM devices. Amateur satellite operations are not permitted, and the ITU's allocations are the same in all three ITU Regions.[1]
Some administrations have authorized spectrum for amateur use in this region; others have declined to regulate frequencies above 300 GHz.
[v] All allocations are subject to variation by country. For simplicity, only common allocations found internationally are listed. See a band's article for specifics.
[w] HF allocation created at the 1979 World Administrative Radio Conference. These are commonly called the "WARC bands".
[x] This is not mentioned in the ITU's Table of Frequency Allocations, but many individual administrations have commonly adopted this allocation under "Article 4.4".
[y] This includes a currently active footnote allocation mentioned in the ITU's Table of Frequency Allocations. These allocations may only apply to a group of countries.
