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Allocations

Intro to Allocations

U.S. Non-Federal-Government Allocations

2900 - 3100 MHz
MARITIME RADIONAVIGATION
Radiolocation US44

5.427 US316

FCC Rule Parts:
Maritime (80)
Private Land Mobile (90)

U.S. Federal Government Allocations

2900 - 3100 MHz
RADIOLOCATION 5.424A G56
MARITIME RADIONAVIGATION

5.427 US44 US316

ITU Region 1 Allocations

2900 - 3100 MHz
RADIOLOCATION 5.424A
RADIONAVIGATION 5.426

5.425 5.427

ITU Region 2 Allocations

2900 - 3100 MHz
RADIOLOCATION 5.424A
RADIONAVIGATION 5.426

5.425 5.427

ITU Region 3 Allocations

2900 - 3100 MHz
RADIOLOCATION 5.424A
RADIONAVIGATION 5.426

5.425 5.427

SpectrumWiki

SPY-1 Shipborne Air Surveillance Radar

NEXRAD Weather Radar

Airport Surveillance Radar (ASR-11)

Through-wall Radar waiver

Footnotes

5.424A In the band 2900-3100 MHz, stations in the radiolocation service shall not cause harmful interference to, nor claim protection from, radar systems in the radionavigation service.

5.425 In the band 2900-3100 MHz, the use of the shipborne interrogator-transponder (SIT) system shall be confined to the sub-band 2930-2950 MHz.

5.426 The use of the band 2900-3100 MHz by the aeronautical radionavigation service is limited to ground-based radars.

5.427 In the bands 2900-3100 MHz and 9300-9500 MHz, the response from radar transponders shall not be capable of being confused with the response from radar beacons (racons) and shall not cause interference to ship or aeronautical radars in the radionavigation service, having regard, however, to No. 4.9.

US44 In the band 2900-3100 MHz, the non-Federal radiolocation service may be authorized on the condition that no harmful interference is caused to Federal services.

US316 The band 2900-3000 MHz is also allocated to the meteorological aids service on a primary basis for Federal use. Operations in this service are limited to Next Generation Weather Radar (NEXRAD) systems where accommodation in the band 2700-2900 MHz is not technically practical and are subject to coordination with existing authorized stations.

G56 Federal radiolocation in the bands 1215-1300, 2900-3100, 5350-5650 and 9300-9500 MHz is primarily for the military services; however, limited secondary use is permitted by other Federal agencies in support of experimentation and research programs. In addition, limited secondary use is permitted for survey operations in the band 2900-3100 MHz.

SpectrumWiki

SPY-1 Shipborne Air Surveillance Radar

The SPY-1 is a U.S. Navy phased array surveillance radar that is a component of the Aegis combat system. It is installed on guided missile cruisers (CG) and guided missile destroyers (DDG). Several variants of the SPY-1, including the -1A, -1B(V), -1D, and -1F are in service, modified to fit specific types of vessels. The -1F is not installed on any U.S. ships.

U.S. land-based test and training sites for the SPY-1 are at Moorestown, NJ, and Wallops Island, VA.

The SPY-1 possesses the following technical characteristics according to ITU-R Recommendation M.1465:

-Modulation: Q7N (angle-modulated, two or more digital channels, no information transmitted)

-Tuning range: 3100-3500 MHz

-Peak tx power into antenna: 4 – 6.4 MW (66 – 68 dBW)

-Antenna gain: 42 dBi

-Peak EIRP: 63 – 101 GW (108-110 dBW)

-Pulse width: 6.4 – 51.2 microseconds

-Pulse repetition rate: 0.152-6 kHz

-Duty cycle: 0.8-2.0%

-Tx bandwidth (-3 dB): 4 MHz

-Average EIRP (=peak EIRP x duty cycle): 504 MW – 2 GW (87-93 dBW)

-Minimum effective isotropic power spectral density: 126 W/Hz (51 dBm/Hz)

-Maximum effective power isotropic spectral density: 500 W/Hz (57 dBm/Hz)

-Antenna type: Phased array

-Beamwidth: 1.7 deg (azimuth and elevation)

-Polarization: Vertical

-Antenna rotation rate: N/A (electronically steered)

The SPY-1 is known to emit very high levels of out-of-band emissions outside of the 3100-3500 MHz band.

Frequency Bands
Band	Use	Service	Table
3100 - 3500 MHz	SPY-1 Shipborne Air Surveillance Radar	Radiolocation	F

Associated Files:

SPY-1 phased array antenna panels on the guided missile destroyer USS Laboon, photographed in the Chesapeake Bay near Norfolk, Virginia.

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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:

NTIA Technical Report 13-490

NWS Radar Operations Center

Map of NEXRAD radar sites (NOAA)

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Airport Surveillance Radar (ASR-11)

According to the FAA:

Airport Surveillance Radar (ASR-11) is an integrated primary and secondary radar system that has been deployed at terminal air traffic control sites. It interfaces with both legacy and digital automation systems and provides six-level national weather service calibrated weather capability that provides enhanced situational awareness for both controllers and pilots.

The primary surveillance radar uses a continually rotating antenna mounted on a tower to transmit electromagnetic waves that reflect, or backscatter, from the surface of aircraft up to 60 nautical miles from the radar. The radar system measures the time required for radar to echo to return and the direction of the signal. From this, the system can then measure the distance of the aircraft from the radar antenna and the azimuth, or direction, of the aircraft in relation to the antenna. The primary radar also provides data on six levels of rainfall intensity and operates in the range of 2700 to 2900 MHz. The transmitter generates a peak effective power of 25 kW and an average power of 2.1 kW. The average power density of the ASR-11 signal decreases with distance from the antenna. At distances of more than 43 feet from the antenna, the power density of the ASR-11 signal falls below the maximum permissible exposure levels established by the Federal Communications Commission (FCC).

The secondary surveillance radar uses a second radar beacon antenna attached to the top of the primary radar antenna to transmit and receive area aircraft data for barometric altitude, identification code, and emergency conditions. Military, commercial, and some general aviation aircraft have transponders that automatically respond to a signal from the secondary radar by reporting an identification code and altitude. The air traffic control centers uses this system data to verify the location of aircraft within a 60-mile radius of the radar site. The secondary radar also provides rapid identification of aircraft in distress. The secondary radar operates in the range of 1030 to 1090 MHz. Transmitting power ranges from 160 to 1500 watts.

Frequency Bands
Band	Use	Service	Table
1030 - 1090 MHz	Airport Surveillance Radar (ASR-11) secondary radar band	Aeronautical Radionavigation	F
2700 - 2900 MHz	Airport Surveillance Radar (ASR-11) primary radar band	Aeronautical Radionavigation	F

External Links:

Airport Surveillance Radar (ASR-11) (FAA)

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Through-wall Radar waiver

Under a waiver granted to L-3 CyTerra, a division of L-3
Communications Corporation, the company can certify and market frequency-stepping radars in the 3100-3500 MHz band. Units must be licensed under Part 90 of the FCC rules. Terms of the waiver limit eligibility to state and local police and firefighters, and limit use to actual emergencies involving threats to safety of life, and necessary training. Another company has received an identical "me too" waiver.

Frequency Bands
Band	Use	Service	Table
3100 - 3500 MHz	L-3 CyTerra through-wall radar	Radiolocation	N

External Links:

CyTerra waiver grant

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Occupancy Measurements (10)

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Engineering Data

	Lower Frequency	Center Frequency	Upper Frequency
Frequency	2900 MHz	3 GHz	3.1 GHz
Wavelength	10.3 cm	10.0 cm	9.7 cm
Band designator(s)	UHF; S-band (IEEE)	SHF; S-band (IEEE)	SHF; S-band (IEEE)
Isotropic collecting area	8.5 cm²	7.9 cm²	7.4 cm²
Free space loss (1 m)	41.7 dB	42.0 dB	42.3 dB
Free space loss (1 km)	101.7 dB	102.0 dB	102.3 dB
Free space loss (10 km)	121.7 dB	122.0 dB	122.3 dB
Free space loss (100 km)	141.7 dB	142.0 dB	142.3 dB
Free space loss (1000 km)	161.7 dB	162.0 dB	162.3 dB
Free space loss (35,786 km = GEO orbit)	192.8 dB	193.1 dB	193.4 dB
Free space loss (378,370 km = Moon)	213.3 dB	213.6 dB	213.8 dB