U.S. Non-Federal-Government Allocations
275 - 1000 GHz

FCC Rule Parts:
Amateur Radio (97)

U.S. Federal Government Allocations
275 - 1000 GHz

ITU Region 1 Allocations
275 - 3000 GHz

ITU Region 2 Allocations
275 - 3000 GHz

ITU Region 3 Allocations
275 - 3000 GHz



5.565 The frequency band 275-1000 GHz may be used by administrations for experimentation with, and development of, various active and passive services. In this band a need has been identified for the following spectral line measurements for passive services:

  • radio astronomy service: 275-323 GHz, 327-371 GHz, 388-424 GHz, 426-442 GHz, 453-510 GHz, 623-711 GHz, 795-909 GHz and 926-945 GHz;
  • Earth exploration-satellite service (passive) and space research service (passive): 275-277 GHz, 294-306 GHz, 316-334 GHz, 342-349 GHz, 363-365 GHz, 371-389 GHz, 416-434 GHz, 442-444 GHz, 496-506 GHz, 546-568 GHz, 624-629 GHz, 634-654 GHz, 659-661 GHz, 684-692 GHz, 730-732 GHz, 851-853 GHz and 951-956 GHz.

Future research in this largely unexplored spectral region may yield additional spectral lines and continuum bands of interest to the passive services. Administrations are urged to take all practicable steps to protect these passive services from harmful interference until the date when the allocation Table is established in the above-mentioned frequency band.

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WRC-23 Agenda Item 1.16, Non-GSO FSS earth stations in motion
Globalstar (MSS, ATC, & TLPS)
Aeronautical Radio Altimeters
Direct Broadcast Satellite TV
DISH Network
Satellite Digital Audio Radio Service (SDARS) (Sirius & XM)
4.9 GHz Public Safety Spectrum
24 GHz Market Area Service
NTIA Spectrum Use Summary
Advanced Extremely High Frequency (AEHF) Military Satellite System
Geostationary Fixed Satellite Service (GSO FSS)
NASA Deep Space Network (DSN)
Wideband Global SATCOM (WGS) System
Standard LTE Bands
NASA Tracking and Data Relay Satellite System (TDRSS)
Defense Satellite Communication System 3 (DSCS III)
ViaSat-1 Ka-band Satellite
4 GHz Fixed Service Band
Dedicated Spectrum for UAVs
Unlicensed bands
6 GHz Fixed Service Band
Industrial, Scientific, and Medical Devices (ISM, FCC Part 18)
Hughes Network Systems EchoStar XVII (Jupiter-1)
Citizens Broadband Radio Service (CBRS)
Common Carrier Fixed Point-to-Point Microwave
Radiofrequency Identification (RFID)
Airport Surface Detection Radars (ASDE-X)
Airport Surface Detection Radars (ASDE-3)
Terminal Doppler Weather Radar
NEXRAD Weather Radar
FCC Proposed Rules for Citizens Broadband Service
Airborne Doppler Radar Navigation Equipment
802.11ad (WiGig)
Mobile User Objective System (MUOS)
Proposed Air-Ground Broadband for Passengers Aboard Aircraft
Ligado Networks
SPN-43 Shipborne Radar
SPY-1 Shipborne Air Surveillance Radar
Local Multipoint Distribution Service (LMDS)
70/80/90 GHz Bands
2019 World Radiocommunication Conference (WRC-19) Agenda Item 1.16
UK Broadband
WRC 23 Agenda Item 1.2 IMT identification
WRC-23 Agenda Item 1.3
WRC-23 Agenda Item 1.14 Possible Adjustments to EESS (passive) Allocations
WRC-23 Agenda Item 1.15 Harmonization of 12.75-13.25 GHz
Military Troposcatter Systems
Unlicensed Level Probing Radars
Review use by FSS, 2015 World Radiocommunication Conference (WRC-15) Agenda Item 1.7
Dedicated Short Range Communications (DSRC)
Skybox high-resolution imaging satellites
Other 3 billion (03b) Networks
Radio Astronomy Formaldehyde (H2CO) Observations
Multichannel Video Distribution & Data Service (MVDDS)
WRC-23 Agenda Item 1.1
ARC-23 Agenda Item 1.13
WRC-23 Agenda Item 1.19, Consider New FSS S2E Primary Allocation in Region 2
Wideband Systems under 15.250
Foreign Object Debris (FOD) detection radars
Through-wall Radar waiver
Airport Body Scanners
High Altitude Platform Station (HAPS)
2019 World Radiocommunication Conference (WRC-19) Agenda Item 1.5
Possible new FSS allocations, 2015 World Radiocommunication Conference (WRC-15) Agenda Item 1.6
Possible allocations for FSS and maritime mobile-satellite service, 2015 World Radiocommunication Conference (WRC-15) Agenda Item 1.9
Possible new FSS and maritime mobile-satellite allocations, 2015 World Radiocommunication Conference (WRC-15) Agenda Item 1.9
Possible MSS Allocations (WRC-15 Agenda Item 1.10)
Possible new primary EESS allocation (WRC-15 Agenda Item 1.11)
Possible extension of EESS (active) allocation (WRC-15 Agenda Item 1.12)
Possible future primary allocation for automotive radars (WRC-15 Agenda Item 1.18)
Actions to support FSS Earth stations in 3400-4200 MHz (WRC-15 Agenda Item 9.1.5)
DARPA Video Synthetic Aperture Radar (ViSAR)
2019 World Radiocommunication Conference (WRC-19) Agenda Item 1.6
2019 World Radiocommunication Conference (WRC-19) Agenda Item 1.15
2023 World Radiocommunication Conference (WRC-23) Preliminary Agenda Item 2.4
WRC-27 study for aeronautical and maritime earth stations in motion for Earth-to-space transmissions
WRC-27 agenda item regarding FSS uplink antenna sizes
WRC-27 agenda item regarding NGSO FSS gateway earth stations (Earth-to-space)
WRC-27 agenda item for new primary FSS and BSS allocations and EPFD limits
WRC-27 agenda item regarding technical/regulatory rules for FSS networks for equitable access
WRC-27 study for potential IMT use
WRC-27 study for radiolocation use
WRC-27 consideration of satellite power limits to protect fixed and mobile services
WRC-27 consideration of EESS (passive) allocations
Google Project Loon
WRC-19 Agenda Item 1.5

Related Documents, Links, and Multimedia:
FCC Proceeding (18)
White Paper (2)
Occupancy Measurements (9)
Band Plan (1)
Legislation (1)
Other (6)

Engineering Data

Lower Frequency Center Frequency Upper Frequency
Frequency 275 GHz 1.6375 THz 3 THz
Wavelength 1.1 mm 183.1 microns 99.9 microns
Band designator(s) EHF (millimeter wave) THz wave THz wave
Isotropic collecting area 0.095 mm2 0.003 mm2 0.001 mm2
Free space loss (1 m) 81.2 dB 96.7 dB 102.0 dB
Free space loss (1 km) 141.2 dB 156.7 dB 162.0 dB
Free space loss (10 km) 161.2 dB 176.7 dB 182.0 dB
Free space loss (100 km) 181.2 dB 196.7 dB 202.0 dB
Free space loss (1000 km) 201.2 dB 216.7 dB 222.0 dB
Free space loss
(35,786 km = GEO orbit)
232.3 dB 247.8 dB 253.1 dB
Free space loss (378,370 km = Moon) 252.8 dB 268.3 dB 273.6 dB