Radio Regulations

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

1.1

WRC-27 · Agenda item 1.1

to consider the technical and operational conditions for the use of the frequency bands 47.2-50.2 GHz and 50.4-51.4 GHz (Earth-to-space), or parts thereof, by aeronautical and maritime earth stations in motion communicating with space stations in the fixed-satellite service and develop regulatory measures, as appropriate, to facilitate the use of the frequency bands 47.2-50.2 GHz and 50.4-51.4 GHz (Earth-to-space), or parts thereof, by aeronautical and maritime earth stations in motion communicating with geostationary space stations and non-geostationary space stations in the fixed-satellite service, in accordance with Resolution 176 (Rev.WRC-23)

Current WP 4A Res. 176 (Rev.WRC-23) › 47.2–50.2 GHz 50.4–51.4 GHz

Shared frequency bands

Bands this agenda item addresses jointly with other WRC-27 items (CPM Report Table 1). Click a band to open its spectrum page.

47.2–50.2 GHz 50.4–51.4 GHz

Also studied under: AI 1.6

At a glance Summary & background Regulatory Studies

At a glance Beta

Frequency band

47.2–50.2 GHz 50.4–51.4 GHz

Governing resolution

Res. 176 (Rev.WRC-23)

Responsible group WP 4A

Agenda-item type Technical

The band and its sensitive neighbours

FIXED

Fixed satellite

MOBILE

Earth exploration-satellite

Radio astronomy

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
FIXED-SATELLITE (Earth-to-space) (space-to-Earth)	Primary Region 1 only
Mobile-satellite (Earth-to-space)	Secondary

Key figures in today's rules

Parameter	GSO	Non-GSO
PFD at radio-astronomy sites 48.94–49.04 GHz, from GSO FSS space stations in 48.2–48.54 / 49.44–50.2 GHz (No. 5.555B)	≤ −151.8 dB(W/m²·500 kHz)	—
Unwanted emissions near the passive band operations in 49.7–50.2 / 50.4–50.9 GHz (No. 5.338A)	Res. 750 limits apply
Safety-of-life use of ESIMs	not permitted (Res. 176)

Reference figures, verified against the Radio Regulations.

What's being studied — points to watch

Adjacent passive band

Keep ESIM out-of-band emissions out of 50.2–50.4 GHz (EESS/SRS passive), where sensing needs near-total protection.

Aeronautical ESIM reach

High-altitude, wide-coverage aircraft terminals raise cross-border coordination and interference to terrestrial fixed/mobile.

Non-GSO aggregation

Many moving NGSO terminals sum up; conditions must bound the aggregate into GSO networks and the ground.

Radio astronomy

Protect the 48.94–49.04 GHz radio-astronomy band (No. 5.149) from ESIM emissions.

Maritime vs aeronautical

Sea-surface and airborne terminals behave differently; the conditions may need to differ by ESIM type.

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.