Radio amateurs may engage in satellite and space craft communications; however, the frequencies allowed for such activities are allocated separately from more general use radio amateur bands.
Under the International Telecommunication Union’s rules, all amateur radio operations may only occur within 50 kilometres (31 mi) of the Earth’s surface. As such, the Amateur Radio Service is not permitted to engage in satellite operations; however, a sister radio service, called the Amateur Satellite Service, exists which allows satellite operations for the same purposes as the Amateur Radio Service. In most countries, an amateur radio license conveys operating privileges in both services, and in practice, the legal distinction between the two services is transparent to the average licensee. The primary reason the two services are separate is to limit the frequencies available for satellite operations. Due to the shared nature of the amateur radio allocations internationally, and the nature of satellites to roam worldwide, the ITU does not consider all amateur radio bands appropriate for satellite operations. Being separate from the Amateur Radio Service, the Amateur Satellite Service receives its own frequency allocations. All the allocations are within amateur radio bands, and with one exception, the allocations are the same in all three ITU regions. Some of the allocations are limited by the ITU in what direction transmissions may be sent (EG: “Earth-to-space” or up-links only).
All amateur satellite operations occur within the allocations tabled below, except for AO-7, which has an up-link from 432.125 MHz to 432.175 MHz.
| International amateur satellite frequency allocations | ||||||
|---|---|---|---|---|---|---|
| Range | Band | Letter1 | Allocation | Preferred sub-bands | User status | Notes |
| HF | 40 m | 7.000 MHz – 7.100 MHz | Primary | |||
| 20 m | 14.000 MHz – 14.250 MHz | Primary | ||||
| 17 m | 18.068 MHz – 18.168 MHz | Primary | Entire amateur radio band | |||
| 15 m | H | 21.000 MHz – 21.450 MHz | Primary | Entire amateur radio band | ||
| 12 m | 24.890 MHz – 25.990 MHz | Primary | Entire amateur radio band | |||
| 10 m | A | 28.000 MHz – 29.700 MHz | 29.300 MHz – 29.510 MHz | Primary | Entire amateur radio band | |
| VHF | 2 m | V | 144.000 MHz – 146.000 MHz | 145.800 MHz – 146.000 MHz | Primary | |
| UHF | 70 cm | U | 435.000 MHz – 438.000 MHz | NIB3 | ||
| 23 cm | L | 1.260 GHz – 1.270 GHz | NIB3 | Only uplinks allowed | ||
| 13 cm | S | 2.400 GHz – 2.450 GHz | 2.400 GHz – 2.403 GHz | NIB3 | ||
| SHF | 9 cm | S2 | 3.400 GHz – 3.410 GHz | NIB3 | Not available in ITU region 1. | |
| 5 cm | C | 5.650 GHz – 5.670 GHz | NIB3 | Only uplinks allowed | ||
| 5.830 GHz – 5.850 GHz | Secondary | Only downlinks allowed | ||||
| 3 cm | X | 10.450 GHz – 10.500 GHz | Secondary | |||
| 1.2 cm | K | 24.000 GHz – 24.050 GHz | Primary | |||
| EHF | 6 mm | R | 47.000 GHz – 47.200 GHz | Primary | Entire amateur radio band | |
| 4 mm | 76.000 GHz – 77.500 GHz | Secondary | ||||
| 77.500 GHz – 78.000 GHz | Primary | |||||
| 78.000 GHz – 81.000 GHz | Secondary | |||||
| 2 mm | 134.000 GHz – 136.000 GHz | Primary | Entire amateur radio band | |||
| 136.000 GHz – 141.000 GHz | Secondary | |||||
| 1 mm | 241.000 GHz – 248.000 GHz | Secondary | Entire amateur radio band | |||
| 248.000 GHz – 250.000 GHz | Primary | |||||
| 1 AMSAT band letters. Not all bands have been assigned a letter by AMSAT. 2 For some allocations, satellite operations are predominately concentrated in a sub-band of the allocation. 3 Footnote allocation. Use is only allowed on a non-interference basis to other users, as per ITU footnote 5.282. 4 No amateur satellite operations have yet occurred at EHF; however, AMSAT’s P3E is planned to have an R band down-link. |
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