The 4 millimeter band is a portion of the EHF

EHF

EHF may stand for:* EHF – therapy * Extremely High Frequency, a radio frequency band* Ebola hemorrhagic fever, an illness* European Handball Federation, the European governing body for handball...

 (microwave

Microwave

Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...

) radio spectrum internationally allocated to amateur radio

Amateur radio

Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...

 and amateur satellite use. The amateur radio and amateur satellite band is between 76.0 GHz and 81.0 GHz. Amateurs operate on a primary basis between 77.5 GHz and 78.0 GHz and on a secondary basis in the rest of the band. Also, 81.0 GHz to 81.5 GHz is allocated by ITU

Itu

Itu is an old and historic municipality in the state of São Paulo in Brazil. The population in 2009 was 157,384 and the area is 641.68 km². The elevation is 583 m. This place name comes from the Tupi language, meaning big waterfall. Itu is linked with the highway numbered the SP-75 and are flowed...

 footnote 5.561A to the amateur and amateur-satellite services on a secondary basis. The ITU's allocations are the same in all three ITU region

ITU region

The International Telecommunication Union , in its International Radio Regulations, divides the world into three ITU regions for the purposes of managing the global radio spectrum...

s.

Until 2006, 75.5 GHz to 76.0 GHz was also allocated by the ITU to amateurs on a primary basis. In response to this change, CEPT

European Conference of Postal and Telecommunications Administrations

The European Conference of Postal and Telecommunications Administrations was established on June 26, 1959, as a coordinating body for European state telecommunications and postal organizations...

 added footnote EU35 to the "European Common Allocation Table", which provides a continued allocation of this segment to European

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

amateurs.

Frequencies of note

• 75,500.1 MHz GHz Old Narrow Band Calling Frequency, still in use in some countries.