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Allocations

U.S. Non-Federal-Government Allocations

2700 - 2900 MHz

5.423 US18

FCC Rule Parts:
Aviation (87)

U.S. Federal Government Allocations

2700 - 2900 MHz
METEOROLOGICAL AIDS
AERONAUTICAL RADIONAVIGATION 5.337 US18
Radiolocation G2

5.423 G15

ITU Region 1 Allocations

2700 - 2900 MHz
AERONAUTICAL RADIONAVIGATION 5.337
Radiolocation

5.423 5.424

ITU Region 2 Allocations

2700 - 2900 MHz
AERONAUTICAL RADIONAVIGATION 5.337
Radiolocation

5.423 5.424

ITU Region 3 Allocations

2700 - 2900 MHz
AERONAUTICAL RADIONAVIGATION 5.337
Radiolocation

5.423 5.424

SpectrumWiki

NEXRAD Weather Radar

Solar Flux Index (SFI)

Footnotes

5.337 The use of the bands 1300-1350 MHz, 2700-2900 MHz and 9000-9200 MHz by the aeronautical radionavigation service is restricted to ground-based radars and to associated airborne transponders which transmit only on frequencies in these bands and only when actuated by radars operating in the same band.

5.423 In the band 2700-2900 MHz, ground-based radars used for meteorological purposes are authorized to operate on a basis of equality with stations of the aeronautical radionavigation service.

5.424 Additional allocation: in Canada, the band 2850-2900 MHz is also allocated to the maritime radionavigation service, on a primary basis, for use by shore-based radars.

US18 In the bands 9-14 kHz, 90-110 kHz, 190-415 kHz, 510-535 kHz, and 2700-2900 MHz, navigation aids in the U.S. and its insular areas are normally operated by the Federal Government. However, authorizations may be made by the FCC for non-Federal operations in these bands subject to the conclusion of appropriate arrangements between the FCC and the Federal agencies concerned and upon special showing of need for service which the Federal Government is not yet prepared to render.

G2 In the bands 216.965-216.995 MHz, 420-450 MHz (except as provided for in G129), 890-902 MHz, 928-942 MHz, 1300-1390 MHz, 2310-2390 MHz, 2417-2450 MHz, 2700-2900 MHz, 3300-3500 MHz (except as provided for in US108), 5650-5925 MHz, and 9000-9200 MHz, use of the Federal radiolocation service is restricted to the military services.

G15 Use of the band 2700-2900 MHz by the military fixed and shipborne air defense radiolocation installations will be fully coordinated with the meteorological aids and aeronautical radionavigation services. The military air defense installations will be moved from the band 2700-2900 MHz at the earliest practicable date. Until such time as military air defense installations can be accommodated satisfactorily elsewhere in the spectrum, such operations will, insofar as practicable, be adjusted to meet the requirements of the aeronautical radionavigation service.

SpectrumWiki

NEXRAD Weather Radar

In the United States, NEXt-generation weather RADars (NEXRAD) operate in the band 2700-3000 MHz. The radars are WSR-88D (Weather Surveillance Radar - 1988 Doppler) models. According to the National Weather Service, there are 160 operational NEXRAD radars throughout the U.S. and at some overseas locations.
According to NTIA technical report 13-490, the lowest tuned frequency for any NEXRAD is 2705 MHz, and the radars have the following technical characteristics:

Peak transmitter power	750 kW
Transmitter type	klystron tube
Operational frequency range	2700-3000 MHz
Antenna type	9 m (28 ft) diameter parabolic reflector with microwave feed horn at power center
Antenna gain	45.5 dBi
Antenna height above ground	24 m (80 ft)
Antenna beam width	0.95 deg (3 dB width) 0.15 deg (boresight accuracy)
Antenna sidelobe levels	At least 27 dB below main-beam gain
Antenna beam scanning protocol	conical scan, +0.5 deg to +20 deg elevation
Antenna beam scanning rate	6 rpm (10 sec/scan revolution interval)
Transmitted pulse widths	short pulse: 1.6 microsec long Pulse: 4.5 microsec
Transmitted pulse modulation	P0N (unmodulated CW pulses)
Transmitted pulse repetition rates	short pulse: 318 to 1304 pulses/sec long pulse: 318 to 452 pulses/sec
Receiver bandwidth	0.795 MHz

Frequency Bands
Band	Use	Service	Table
2700 - 3000 MHz	NEXRAD Weather Radar	Meteorological Aids	F

External Links:

NWS Radar Operations Center

NTIA Technical Report 13-490

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Solar Flux Index (SFI)

The flux density of radio emissions from the Sun has been measured at a frequency of 2800 MHz since approximatey 1950. This solar flux measurement is referred to as F10.7, because 2800 MHz corresponds to a wavelength of 10.7 cm. F10.7 is strongly correlated with the amount of UV radiation coming from the Sun, but can be measured on the ground, as opposed to UV measurements which must be measured from space, above the absorption of the Earth's atmosphere. Making accurate long-term ground-based radio measurements is more reliable and less costly than producing long-term space-based UV measurements.

The amount of solar UV energy, as traced by F10.7, is an important assessment of ionization in the Earth's ionosphere, which in turn has a major impact on radio communications on Earth. F10.7 can also be used to study solar storms, which can produce major disruptions to satellite systems and terrestrial power grids.

F10.7 has always been measured by Canadian radio astronomy stations. It is presently produced by the Dominion Radio Astrophysical Observatory (DRAO) near Penticton, British Columbia.

F10.7, also called the Solar Flux Index (SFI), is measured in a 100 MHz bandwidth from 2750-2850 MHz. It is in units of 10^-22 W/m^2/Hz.

A good article on measurement of the Solar Flux Index appeared in the February 2013 issue of QST magazine.

Frequency Bands
Band	Use	Service	Table
2750 - 2850 MHz	Solar Flux Index (SFI)	Radio Astronomy	-

External Links:

DRAO (Wikipedia)

QST magazine (ARRL)

Latest solar flux report from DRAO

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Related Documents, Links, and Multimedia:

Occupancy Measurements (10)

Other (1)

The Karl G. Jansky Very Large Array (VLA) near Socorro, New Mexico, is capable of observing cosmic radio emissions at any frequency within the range of 1-50 GHz, but has regulatory protections only in bands allocated to the radio astronomy service. The VLA is operated by the National Radio Astronomy Observatory, and is funded by the National Science Foundation.

Frequencies/Bands

1400 - 1427 MHz

1610.6 - 1613.8 MHz

1660 - 1670 MHz

2655 - 2700 MHz

4990 - 5000 MHz

10.68 - 10.7 GHz

15.35 - 15.4 GHz

22.21 - 22.5 GHz

23.6 - 24 GHz

31.3 - 31.8 GHz

42.5 - 43.5 GHz

Services

Radio Astronomy

Document type and status: Other (Current)
Document date or date of hyperlink query: January 19, 2012

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Engineering Data

	Lower Frequency	Center Frequency	Upper Frequency
Frequency	2700 MHz	2800 MHz	2900 MHz
Wavelength	11.1 cm	10.7 cm	10.3 cm
Band designator(s)	UHF; S-band (IEEE)	UHF; S-band (IEEE)	UHF; S-band (IEEE)
Isotropic collecting area	9.8 cm²	9.1 cm²	8.5 cm²
Free space loss (1 m)	41.1 dB	41.4 dB	41.7 dB
Free space loss (1 km)	101.1 dB	101.4 dB	101.7 dB
Free space loss (10 km)	121.1 dB	121.4 dB	121.7 dB
Free space loss (100 km)	141.1 dB	141.4 dB	141.7 dB
Free space loss (1000 km)	161.1 dB	161.4 dB	161.7 dB
Free space loss (35,786 km = GEO orbit)	192.2 dB	192.5 dB	192.8 dB
Free space loss (378,370 km = Moon)	212.6 dB	213.0 dB	213.3 dB