Satellite Communications/GSO arc


Dear Sir,
Please let us know orbital spacing spec for different satellite bands (e.g. C, Ku and Ka) for different services (e.g. FSS, BSS).
Is it different for ITU regions 1, 2 & 3?
Also quote ITU-R no.
Thanks & Regards.


The ITU Radio Regulations (RR) has an allocation structure (Article 5 of the RR) and associated principles that are the basis for the planning and implementation of radio-telecommunication services. The current allocation method uses a block allocation methodology with footnotes.
The RR addresses the frequency range from 9 kHz to 1,000 GHz, and it segments the range into smaller bands that are allocated to over 40 telecommunication services. The radio services are identified as primary or secondary. The secondary services shall cause no harmful interference to, or claim protection from, a primary service. Footnotes are used to further specify how the frequencies are to be assigned or used.

The RR segments the earth into four regions:
•   Region 1A comprises the former Soviet Union.
•   Region 1B comprises Africa, the Saudi Arabian peninsula, Europe including Iceland but not Greenland.
•   Region 2 comprise the America (North, Central, and South) as well as Greenland
•   Region 3 comprises the Indian subcontinent, Southwest Asia, China, Korea, Japan, Indonesia, Philippines, Australia, New Zealand, …

The Appendices to the Radio Regulations provide the details for the various allocations, which are far too numerous to summarize here. One can download at no cost the Appendices at

If for some reason you are unable to download the Appendices, please email me at and I will send you a copy – it is 811 pages and about 6 MB.
You asked specifically about frequency allocations for each category of service for each ITU region.

Broadcast Satellite Services
Broadcast Frequencies (downlinks)
Appendix 30 starting at page 477 addresses broadcast satellite services in the frequency bands 11.7-12.2 GHz (in Region 3), 11.7-12.5- GHz (in Regions 1), and 12.2-12.7 GHz (in Region 2).
Feeder Frequencies (uplinks)

Appendix 30A starting at page 629 addresses feeder links for the broadcasting satellite service (11.7-12.5 GHz in Region 1, 12.2-12.7 GHz in Region 2 and 11.7-12.2 GHz in Region 3) in the frequency bands 14.5-14.8 GHz and 17.3-18.1 GHz in Regions 1 and 3, and 17.3-17.8 GHz in Region 2.

The frequencies by region are summarized in the following table. The following table does not come through clearly--there are three frequencies ranges for each region: the first is the broadcast frequencies; the second and third are both feeder frequencies.

Region   Broadcast Freq. (GHz)   Feeder Freq. (GHz)

1   11.7-12.5          11.7-12.5

2   12.2-12.7          12.2-12.7

3   11.7-12.2          11.7-12.2

As you can see, there are some regional differences in frequency allocations. You will also find that the appendices may have provisions applicable to a specific region (e.g., “Provisions applicable to Region 2” on page 488).

Fixed-Satellite Services

Appendix 30B starting at page 767 addresses fixed satellite services in the frequency bands
•   4,500-4,800 MHz (downlink)
•   6.725-7,025 MHz  (uplink)
•   10.70-10.95 GHz (downlink)
•   11.2-11.45 GHz (downlink)
•   12.75-13.25 GHz (uplink)

Satellite Spacing

The Appendices do not specify satellite spacing—the criterion is the maximum amount of interference allowable between nearby satellites. Thus, the details of two adjacent satellites determine the minimum spacing: e.g., carrier modulation, EIRP of the downlink, sidelobe characteristics, and the uplink EB/N0 of the received uplink.

I hope that you find this answer to be useful.

Thank you,

Tom Burke

Satellite Communications

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Thomas E. Burke


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Forty years of experience with satellite communications. Have held roles as system engineer on JPL Mariner 9 program and a program manager for a number of classified communication satellite programs. Served as head of TRW / Defense Communications Division / Engineering Development Operation, a 1,400-person organization responsible for all aspects of classified communication satellite design and development.

Ph.D. Chemistry, California Institute of Technology (1969) B.A. magna cum laude Chemistry, University of Minnesota (1962)

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