Radio Regulations

Source: the Radio Regulations published by the International Telecommunication Union (ITU).

WRC Agenda Item › WRC-27 › AI 1.3

1.3

WRC-27 · Agenda item 1.3

to consider studies relating to the use of the frequency band 51.4-52.4 GHz to enable use by gateway earth stations transmitting to non-geostationary-satellite orbit systems in the fixed-satellite service (Earth-to-space), in accordance with Resolution 130 (WRC-23)

Current WP 4A Res. 130 (WRC-23) › 51.4–52.4 GHz 51.4–54.25 GHz 52.6–54.25 GHz

At a glance Summary & background Regulatory Studies

At a glance Beta

Frequency band

51.4–52.4 GHz 51.4–54.25 GHz 52.6–54.25 GHz

Governing resolution

Res. 130 (WRC-23)

Responsible group WP 4A

Agenda-item type Technical

The band and its sensitive neighbours

FIXED

Fixed satellite

MOBILE

Earth exploration-satellite

Blocks group a service with its direction and mode variants; the table names each allocation as the Radio Regulations name it.

Current framework

Services in this band

FIXED	Primary
FIXED-SATELLITE (Earth-to-space)	Primary
MOBILE	Primary

Key figures in today's rules

Parameter	GSO	Non-GSO
FSS gateway access today No. 5.555C	min. antenna 2.4 m	no access yet
Emissions in the passive bands 50.2–50.4 / 52.6–54.25 GHz	all emissions prohibited (No. 5.340)
Unwanted emissions from FSS Res. 750 (Rev.WRC-19) via No. 5.338A — revision under study	limits apply

Reference figures, verified against the Radio Regulations.

What's being studied — points to watch

Neighbouring passive bands

Keep gateway out-of-band emissions out of 50.2–50.4 and 52.6–54.25 GHz (EESS passive), vital to weather observation.

Terrestrial fixed & mobile

Set PFD/e.i.r.p. so high-power NGSO gateway uplinks do not raise interference to fixed and mobile services.

Revising FSS conditions

Whether the primary FSS allocation's conditions can be adapted for NGSO gateways without reopening the band's balance.

Aggregate from many gateways

Constellations use many gateways; Res. 130 requires the aggregated interference from GSO and NGSO gateways together to be bounded, not just the single-station case.

Radio astronomy (No. 5.556)

Observations at 51.4–54.25 GHz run under national arrangements; Res. 130 tasks studies to set conditions protecting them from NGSO gateway operation.

Protecting GSO networks

Emissions from NGSO gateway earth stations must not degrade GSO FSS space stations (Res. 130; possible extension of Res. 769/770).

Preparation timeline

Dec 2023 WRC-23 agenda adopted

Dec 2023 WRC-23 agenda adopted
Dec 2023 CPM 27-1 studies allocated

Dec 2023 CPM 27-1 studies allocated
ITU-R studies 2026

ITU-R studies 2026
ITU-R studies 2027

ITU-R studies 2027
5–15 Apr 2027 CPM 27-2 final report

5–15 Apr 2027 CPM 27-2 final report
RTO Prep meetings 2027

RTO Prep meetings 2027
11–15 Oct 2027 RA-27

11–15 Oct 2027 RA-27
18 Oct–12 Nov 2027 WRC-27

18 Oct–12 Nov 2027 WRC-27

Dec 2023 WRC-23 agenda adopted
Dec 2023 CPM 27-1 studies allocated
ITU-R studies 2026
ITU-R studies 2027
5–15 Apr 2027 CPM 27-2 final report
RTO Prep meetings 2027
11–15 Oct 2027 RA-27
18 Oct–12 Nov 2027 WRC-27

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Source: ITU Radio Regulations, editions of 2008, 2012, 2016, 2020 and 2024. The English, French and Spanish texts are each taken from the official edition in that language, not translated from one another. Sources and citation.