9-centimeter band
A secondary-use SHF band for amateur radio and satellite.
The 9-centimeter band sits within the SHF (microwave) part of the radio spectrum and is set aside internationally for amateur radio and amateur satellite use. In ITU Regions 1 and 2, the amateur radio portion runs from 3.300 GHz to 3.500 GHz, but only on a secondary basis. The amateur satellite sub-band spans 3.400 GHz to 3.410 GHz, also limited to Regions 1 and 2, and must operate without causing interference to other users, as per ITU footnote 5.282. In Germany and Israel, the range 3.400–3.475 GHz is additionally allocated to the amateur service on a secondary basis (ITU footnote 5.431). Within CEPT’s European Common Allocation Table, footnote EU17 gives European amateurs secondary access to 3.40–3.41 GHz. In the United States, the FCC has recommended removing the amateur service from this band to free it for 5G cellular systems, a move that has drawn strong objections from amateur operators and the ARRL. As of an October 2020 decision, the band remains available on a secondary basis only to those who held a license before that date. (No additional facts provided in the source.) Notable Frequencies - 3.4001 GHz: IARU Region 1 calling frequency and global EME center of activity - 3.4561 GHz: IARU Region 2 calling frequency Frequencies 3.332–3.339 GHz and 3.3458–3.3525 GHz are used by radio astronomers for spectral line observations. Amateur stations voluntarily avoid these frequencies when near a radio telescope. ITU footnote 5.149 encourages all communications in the band to take practical steps to prevent harmful interference to radio astronomy in those ranges. Countries with More Restricted Allocation - Australia: The ACMA allows amateur use of 3.300–3.400 GHz only for Advanced certificate holders, with a maximum power of 120W Px or 400W Py. Operation from 3.400–3.600 GHz is permitted only in remote areas (see Table C, Radiocommunications (Amateur Stations) Class Licence 2023). - Sweden: The Swedish Post and Telecom Authority (PTS) does not recognize 3.4 GHz as an amateur band and has auctioned it for 5G testing. Temporary permits are currently issued only for the 3.400–3.401 GHz range. - Spain: The Ministerio de Asuntos Económicos y Transformación Digital prohibits amateur use of 3.4 GHz, which is now used by 5G services.
- Frequency range amateur radio
- 3.300 GHz to 3.500 GHz
- Frequency range amateur satellite
- 3.400 GHz to 3.410 GHz
- Itu regions
- 1 and 2
- Calling frequency region 1
- 3.4001 GHz
- Calling frequency region 2
- 3.4561 GHz
- Radio astronomy bands
- 3.332–3.339 GHz and 3.3458–3.3525 GHz
- Australia max power
- 120W Px or 400W Py
Lore & Background
The 9-centimeter band is allocated internationally to amateur radio and amateur satellite use on a secondary basis, meaning amateurs must not cause harmful interference to primary users. In Germany and Israel, the band 3.400–3.475 GHz is also allocated to the amateur service on a secondary basis (ITU footnote 5.431). In CEPT's 'European Common Allocation Table', footnote EU17 allocates 3.40 GHz to 3.41 GHz to European amateurs on a secondary basis.
In the US, the FCC is recommending removing the amateur service from this band in order to make room for the 5G cellular system. There have been many objections to this proposal by Amateur Radio operators, including the ARRL. Under an October 2020 decision, it remains available on a secondary basis to those who have acquired the license before October 2020.
Countries have varied restrictions: Australia allocates 3.300 to 3.400 GHz for Advanced certificate holders with a maximum power of 120W Px or 400W Py, and operation from 3.400 to 3.600 GHz is only allowed in remote areas. Sweden does not consider 3.4 GHz to be an amateur band and has auctioned it for 5G test use, though temporary permits in the 3.400–3.401 GHz range are issued. Spain does not allow 3.4 GHz to be used by amateurs, as it is used by 5G services.
Reader's Guide
The 9-centimeter band is notable for its role in amateur satellite communications and as a microwave band for advanced experimentation, though its secondary allocation creates ongoing uncertainty. The band includes IARU calling frequencies: 3.4001 GHz for Region 1 and global EME center of activity, and 3.4561 GHz for Region 2. Radio astronomy observations are protected in the ranges 3.332–3.339 GHz and 3.3458–3.3525 GHz, and ITU footnote 5.149 encourages all radio communications to avoid harmful interference to those observations. The band's future is contested, particularly in the US where the FCC's proposal to remove amateur service for 5G has drawn objections from the ARRL and others. The October 2020 decision preserves access only for those licensed before that date. In Europe, CEPT's EU17 footnote provides a secondary allocation for 3.40–3.41 GHz, while Sweden and Spain have largely excluded amateurs. Australia permits use only for Advanced license holders with power limits. These varied national policies reflect the band's status as a secondary allocation under pressure from commercial mobile services.
Did You Know?
- The amateur satellite band is only 10 MHz wide, from 3.400 GHz to 3.410 GHz.
- The IARU Region 1 calling frequency is 3.4001 GHz, which is also the global EME center of activity.
- Radio astronomers use 3.332–3.339 GHz and 3.3458–3.3525 GHz for spectral line observations.
- In the US, under an October 2020 decision, the band remains available only to those who acquired a license before October 2020.
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