This document represents an overview of Federal and nonfederal spectrum use. In order to serve its purpose as a quick reference, its length has been limited. Therefore, it is not all inclusive in its portrayal of U.S. spectrum requirements or its representation of the allocation table.

Uses are stated in terms of general functions and actual equipment names are not specified. Federal systems and missions which would have necessitated classification of the summary have been omitted, though they represent significant Federal requirements. Also, Federal agencies lease many services from private sector providers. As written, this summary indicates these uses only as nongovernment use of the frequency spectrum. Furthermore, no attempt has been made to evaluate the level of investment of funds in the uses that are discussed.

Allocations, by footnote, to very limited locations have generally been omitted. The summaries of Federal uses have been written to emphasize, to the greatest extent possible, the missions performed, as opposed to the agencies that perform them.

2900-3100 MHz

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Non-Government Allocation and Use

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MARITIME RADIONAVIGATION

Radiolocation

This band is primarily used for maritime radars and radar beacons (racons). Radars of this type are required on cargo and passenger ships by international treaty (SOLAS) for safety purposes. Racons operate in conjunction with maritime radars to provide electronic markers to identify maritime obstructions and navigation points.

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Government Allocation and Use

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MARITIME RADIONAVIGATION

Radiolocation

Federal agencies use this band heavily for shipborne radionavigation radars, vessel traffic systems, and racons.

The military uses this band for high-power 3-D long-range surveillance radars and air traffic control radars.

Also, NEXRAD will operate from 2900-3000 MHz.

NASA performs airborne measurements of rainfall rates over selected ocean areas.

3100-3600 MHz

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Non-Government Allocation and Use

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Radiolocation

Space Research and Earth Exploration-Satellite (FN713 3100-3300)

Amateur (3300-3500)

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Government Allocation and Use

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RADIOLOCATION

AERONAUTICAL RADIONAVIGATION (3500-3600)

Space Research and Earth Exploration-Satellite (FN713 3100-3300)

This band is primarily used for military radiolocation, including several multi-billion dollar defense radar systems. Use of this band for these systems is considered critical to national defense. The high-power mobile radars include airborne, land-based, and shipborne applications.

3600-3700 MHz

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Non-Government Allocation and Use

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FIXED SATELLITE

Radiolocation

INMARSAT and INTELSAT have limited use for fixed satellite service earth stations. Each site must be actively coordinated with the U.S. Government with supporting EMC analysis.

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Government Allocation and Use

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AERONAUTICAL RADIONAVIGATION

RADIOLOCATION

The principal Federal use of this band is to support a Navy radar used for landing operations on aircraft carriers. This high-power radar is operated on Navy ships and at certain shore locations for training.

NTIA has proposed reallocating the 3650-3700 MHz portion of this band for shared nonfederal use by January 1999.

3700-4200 MHz

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Non-Government Allocation and Use

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FIXED

FIXED SATELLITE

Domestic public fixed, Satellite communications

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Government Allocation and Use

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4200-4400 MHz

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Non-Government Allocation and Use

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AERONAUTICAL RADIONAVIGATION

This band is heavily used for radar altimeters on board nongovernment fixed-wing and rotary aircraft.

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Government Allocation and Use

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AERONAUTICAL RADIONAVIGATION

This band is heavily used for radar altimeters on board government fixed-wing and rotary aircraft, as well as spacecraft. Methods for reducing the bandwidth necessary to perform this function are being studied within the CCIR; however, some altimeter functions may not be able to be provided in a reduced bandwidth. Also, significant capital has been invested in current equipment.

4400-4990 MHz

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Non-Government Allocation and Use

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FIXED SATELLITE (4500-4800)

Radio Astronomy (FN US203 4825-4835, FN US257 4950-4990)

Space Research and Earth Exploration-Satellite (FN720 4950-4990)

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Government Allocation and Use

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FIXED

MOBILE

Radio Astronomy (FN US203 4825-4835, FN US257 4950-4990)

Space Research and Earth Exploration-Satellite (FN720 4950-4990)

This band is used by the military services for tactical communications, both line-of-sight and troposcatter. Most are fixed systems.

In addition to extensive transportable fixed service use, the Navy operates air-to-ground data links, drone command and control systems, target control systems, and anti-air warfare data distributions systems. The Navy anti-air warfare systems employ directed high power spread spectrum techniques in a distributed network among ships and aircraft.

Additional uses are for emergency incident response for the Nuclear Emergency Search Team, and target scoring and control. Narrowband and wideband uplinks and downlinks operate in conjunction with aerostats used in law enforcement and drug interdiction missions.

The National Science Foundation performs some continuum observations in the 4950-4990 MHz portion of the band when the 4990-5000 MHz band does not provide adequate bandwidth.

On August 10, 1994, NTIA deleted all government allocations in the 4660-4685 MHz portion of this band. Furthermore, NTIA has proposed reallocating the 4635-4660 MHz portion of this band for nonfederal use by January 1997.

4990-5000 MHz

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Non-Government Allocation and Use

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RADIO ASTRONOMY

Space Research

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Government Allocation and Use

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RADIO ASTRONOMY

Space Research

This band is used extensively in the U.S. and other countries for radio astronomy. It is an excellent band for continuum measurement, because the galactic background continuum radiation is low. Observations of galactic and extragalactic radio sources at these frequencies help to define their spectra, which gives information on the physical parameters of the radiating source.

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