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National Radio Quiet Zone

Deprecation Notice

This information is deprecated in favor of the new NRQZ documentation managed by Observatory Spectrum Management



The National Radio Quiet Zone (NRQZ) was established by the Federal Communications Commission (FCC) in Docket No. 11745 (November 19, 1958) and by the Interdepartment Radio Advisory Committee (IRAC) in Document 3867/2 (March 26, 1958) to minimize possible harmful interference to the National Radio Astronomy Observatory (NRAO) in Green Bank, WV and the radio receiving facilities for the United States Navy in Sugar Grove, WV. The NRQZ is bounded by NAD-83 meridians of longitude at 78d 29m 59.0s W and 80d 29m 59.2s W and latitudes of 37d 30m 0.4s N and 39d 15m 0.4s N, and encloses a land area of approximately 13,000 square miles near the state border between Virginia and West Virginia.

Open the tabs below to review the requirements, processes, and other vital information on the NRQZ.

If you are new to the Coordination process and/or the NRQZ, please watch the video below from our site Director.

VIDEO: Dr. Karen O’Neil briefly explains the NRQZ and the WVRAZ (Opens in YouTube)

Email: NRQZ Administrator | Telephone: (248) 504-9392

NRQZ coordination is required for all new or modifed, permanent, fixed, licensed transmitters inside the NRQZ, as specified for federal transmitters by NTIA manual section 8.3.9 and for non-federal transmitters by the FCC in 47 CFR section 1.924.

The applicable radio services include but are not limited to: Public Mobile, Wireless Communications, Maritime, Aviation, Private Land Mobile, Personal Radio, Fixed Microwave, International Fixed Public, Satellite Communications, Radio Broadcast, Experimental Radio, Auxiliary and Special Broadcast, Cable Television Relay, Amateur Radio, Personal Communications Service, General Wireless Communications Service. Geographic Area Licensed Services are NOT exempt from NRQZ coordination. Applicants for some radio services are required to file their applications through independent frequency coordinators (e.g. APCO, AASHTO, PCIA, and IMSA). The coordinators assume the responsibility of notifying the Interference Office that an FCC application has been filed and hold the application until the Interference Office responds with its evaluation.

Coordination under the West Virginia State Code Chapter 37A “Radio Astronomy Zoning Act” (WVRAZ) may also apply.

NRAO AutoPath Applicant Submission Template

In order to minimize harmful interference to the operations of Green Bank Observatory (GBO) in Green Bank, WV all requests for new or modified, permanent, fixed, assigned, or licensed transmitters within the NRQZ shall be coordinated by the applicant, prior to submission, to the FCC or NTIA, with:

NRQZ Administration Office
Green Bank Observatory
155 Observatory Road
P. O. Box 2
Green Bank
WV 24944

Email: NRQZ Administrator | Telephone: 304-456-2107 During COVID Operations, this number is not monitored (voicemail only). Please send an email to the NRQZ Administrator.

EVALUATION: The NRQZ Office reviews all applications to ensure that the computed power flux density at the reference point does not exceed frequency-dependent thresholds.

In some instances, the transmitter power requested by an applicant exceeds the level that is harmful to observations in Green Bank or Sugar Grove. When this occurs, applicants should discuss possible modifications to their transmitters (e.g. using a directional antenna, relocating the antenna to an area that provides additional terrain shielding, or selecting a different frequency where the power density limits are different) with the Interference Office. In our experience, a technical solution can almost always be found to provide most of the area coverage desired by the applicant while simultaneously minimizing the impact of the interference upon Green Bank or Sugar Grove. In the extremely rare case when differences between the applicant’s desires and the Interference Office’s evaluation cannot be resolved, both the applicant and the Interference Office should forward comments on the transmitter installation to the FCC or IRAC for a final resolution.

We emphasize that the Interference Office has no authority in the granting of an FCC license or a Federal Government frequency assignment. The Interference Office only has the privilege of submitting its comments on a particular transmitter installation to the FCC or IRAC.

Applicants who feel that their applications have been evaluated unfairly or inadequately can contact the office of the Green Bank Site Director for a review of their circumstances.

PROCESS: Download the NRAO AutoPath Applicant Submission Template excel worksheet. The document contains detailed instructions on the information required for processing. Please take special note to the format of the required fields. For example, output transmitter power is in Watts, AMSL/AGL is in meters, and coordinates are dd mm ss.ss where spaces are required between the values.

NOTE: This document can be used for coordination requests of MULTIPLE LOCATIONS, TRANSMITTERS, FREQUENCIES AND EMISSIONS!

Please read and follow all instructions carefully. Send your completed excel worksheet and all supporting documentation to the NRQZ Administrator for evaluation.

Additional information to assist you with your coordination request…

RESULTS: If your proposed system meets the NRAO protection criteria, you will receive a coordination letter suitable to attach to an FCC application or NTIA assignment.

However, should the Effective Radiated Power (ERP) of your transmitter exceed what is allowable under the limit, the following additional information may be requested:

  • A detailed system configuration that includes all system gains and losses.
  • Antenna gain with horizontal and vertical patterns in one degree increments (in Planet or TIA-804-B Antenna File Format).
  • Antenna azimuth (degrees true) and elevation.


The Sugar Grove Research Station is a DOD Communications Facility located in Pendleton County, West Virginia.

It is possible that your evaluation requires coordination from the Sugar Grove Research Station facility. Should this be applicable to your request, the NRQZ office will contact them and coordinate on your behalf. As soon as they have commented, your case will be finalized. Please do not contact them directly!

For all files below – right mouse click to download

NRAO AutoPath Applicant Submission Template – Excel Spreadsheet

Color Map of the NRQZ – JPEG image

Google Earth file of NRQZ – Google Earth KMZ format

Google Earth file of WVRAZ – Google Earth KML format

The reference point for calculations of transmitter power density is the prime focus of the Green Bank Telescope (GBT). The location of the GBT prime focus is:

Latitude: 38d 25m 59.2s N (NAD83)
Longitude: 79d 50m 23.4s W (NAD83)
Ground Elevation: 806 Meters or 2644 Feet AMSL (NAVD88)
Height: 139.6 Meters or 458 Feet AGL

Based on a 20 kHz measurement bandwidth, the calculated power density of the transmitter at the reference point should be less than:

  • 1 x 10-8 W/m2 for frequencies below 54 MHz
  • 1 x 10-12 W/m2 for frequencies from 54 MHz to 108 MHz
  • 1 x 10-14 W/m2 for frequencies from 108 MHz to 470 MHz
  • 1 x 10-17 W/m2 for frequencies from 470 MHz to 1000 MHz
  • freq2 (in GHz) x 10-17 W/m2 for frequencies above 1000 MHz

except for frequencies that reside in the radio astronomy observing bands listed in the US Table of Frequency Allocations, in which case the power densities listed in Table 1 of Recommendation ITU-R RA.769 shall apply. For a comprehensive list, click here.