23-centimeter band
A secondary UHF band for amateur radio and satellite use.
The 23 centimeter band (also called 1200 MHz or 1.2 GHz) sits in the UHF microwave part of the radio spectrum. Amateur radio operators and amateur satellite services can use it, but only as secondary users. The amateur radio portion runs from 1240 MHz to 1300 MHz. The amateur satellite portion is narrower, from 1260 MHz to 1270 MHz, and satellites may only use it for uplinks, provided they do not interfere with other services (per ITU footnote 5.282). These allocations are identical across all three ITU regions. A wide variety of amateur modes are active here, including voice, data, moonbounce (EME), and amateur television (ATV).
Different countries have slightly different band edges. In the United Kingdom, the band extends from 1240 MHz to 1325 MHz. In Ireland, it goes from 1240 MHz to 1304 MHz.
The band’s history starts after World War II. The 1947 International Radio Conference in Atlantic City, New Jersey, set aside 1215 to 1300 MHz exclusively for amateur use. At the 1979 World Administrative Radio Conference in Geneva (WARC-79), the band was cut to 1240–1300 MHz and downgraded to a secondary allocation, giving primary status to the radiolocation service. More recently, Agenda Item AI-9.1b at the 2023 World Radio Conference (WRC-23) looked at adding further restrictions to protect the Radio Navigation Satellite Service (RNSS), which is also a primary user. RNSS systems like Glonass, Compass, and Galileo use this range to supplement their standard GNSS frequencies. In November 2023, ITU-R Recommendation M.2164 was published, offering guidance for amateur and amateur satellite use.
Notable frequencies vary by ITU region. In Region 1, the CW and SSB calling frequency is 1296.2 MHz, and the FM simplex calling frequency is 1297.5 MHz. In Region 2, the CW and SSB calling frequency is 1296.1 MHz, and the FM simplex calling frequency is 1294.5 MHz. In Region 3, the FM simplex calling frequency is 1294.0 MHz (based on the VK Australian band-plan from 2007). The 2008 IARU Region-1 Cavtat Conference designated 1240.000–1240.750 MHz as an alternative center for narrowband activity and beacons, a move to help share the band with existing aviation radars, primary users, and potential issues with the European Galileo system.
- Amateur radio band
- 1240 MHz to 1300 MHz
- Amateur satellite band
- 1260 MHz to 1270 MHz
- Uk band
- 1240 MHz to 1325 MHz
- Ireland band
- 1240 MHz to 1304 MHz
- Region 1 cw ssb calling
- 1296.2 MHz
- Region 1 fm simplex calling
- 1297.5 MHz
- Region 2 cw ssb calling
- 1296.1 MHz
- Region 2 fm simplex calling
- 1294.5 MHz
- Region 3 fm simplex calling
- 1294.0 MHz
Lore & Background
The 23 cm band was born after World War II, at the International Radio Conference celebrated in Atlantic City, New Jersey in 1947. The band was defined from 1215 to 1300 MHz and was allocated exclusively for radio amateur use. In the 1979 World Administrative Radio Conference held in Geneva (WARC-79), the band was reduced to 1240 - 1300 MHz and downgraded to secondary allocation for amateur use, with the primary allocation to the radiolocation service having highest priority. Agenda Item AI-9.1b at the 2023 World Radio Conference (WRC-23) considered further constraints on 23 cm to protect the Radio Navigation Satellite Service (RNSS), which is also a primary user of the band. RNSS systems include Glonass, Compass and Galileo which use this frequency range to supplement their more standard GNSS frequencies. In November 2023 ITU-R Recommendation M.2164 was published, giving guidance for amateur and amateur satellite usage.
Reader's Guide
The 23 cm band is notable for its international allocation across all three ITU regions, though with national variations such as in the United Kingdom (1240-1325 MHz) and Ireland (1240-1304 MHz). Its history reflects a shift from exclusive amateur allocation in 1947 to a secondary status after 1979, requiring amateurs to avoid interference with primary radiolocation services. The band supports a wide variety of modes including voice, data, EME, and ATV, with harmonized calling frequencies differing by region. Recent developments, such as WRC-23 discussions and the 2023 ITU-R Recommendation M.2164, highlight ongoing pressures to protect RNSS systems like Glonass, Compass, and Galileo, which share the band. The IARU Region-1 Cavtat Conference in 2008 designated 1240.000-1240.750 MHz as an alternative centre for narrowband activity and beacons, as a mitigation for sharing with existing aviation radars and primary users, or for potential issues with the European Galileo system. This band remains a dynamic part of amateur radio, balancing historical legacy with modern spectrum challenges.
Did You Know?
- The 23 cm band was originally allocated exclusively for amateur radio use from 1215 to 1300 MHz at the 1947 Atlantic City conference.
- RNSS systems Glonass, Compass, and Galileo use this frequency range to supplement their standard GNSS frequencies.
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