{"data":{"id":"us/47-cfr-74.536","jurisdiction":"us","citation":"47 CFR 74.536","heading":"Directional antenna required.","body":"(a) Aural broadcast STL and ICR stations are required to use a directional antenna with the minimum beamwidth necessary, consistent with good engineering practice, to establish the link.\n(b) An aural broadcast STL or intercity relay station operating in the 17.7-19.7 GHz band shall employ an antenna that meets the performance standards for Category A, except that in areas not subject to frequency congestion, antennas meeting standards for Category B may be employed. However, the Commission may require the replacement, at the licensee's expense, of any antenna or periscope antenna system of a permanent fixed station that does not meet performance Standard A, which is specified in the table in paragraph (c) of this section, upon a showing that said antenna causes or is likely to cause interference to (or receive interference from) any other authorized or proposed station; provided that an antenna meeting performance Standard A is unlikely to involve such interference.\n(c) Licensees shall comply with the antenna standards table shown in this paragraph in the following manner:\n(1) With either the maximum beamwidth to 3 dB points requirement or with the minimum antenna gain requirement; and\n(2) With the minimum radiation suppression to angle requirement.\nAntenna Standards\nFrequency (GHz) Category Maximum beamwidth to 3 dB points 1 (included angle in degrees) Minimum antenna gain (dbi) Minimum radiation suppression to angle in degrees from centerline of main beam in decibels\n5° to 10° 10° to 15° 15° to 20° 20° to 30° 30° to 100° 100° to 140° 140° to 180°\n17.7 to 19.7 A B 2.2 2.2 38 38 25 20 29 24 33 28 36 32 42 35 55 36 55 36\n1 If a licensee chooses to show compliance using maximum beamwidth to 3 dB points, the beamwidth limit shall apply in both the azimuth and the elevation planes.","path":["Title 47—Telecommunication","CHAPTER I—FEDERAL COMMUNICATIONS COMMISSION","SUBCHAPTER C—BROADCAST RADIO SERVICES","PART 74—EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES","Subpart E—Aural Broadcast Auxiliary Stations"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-47.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:28Z","sha256":"5c71b32655d4aea3e96c0e2ffa184cc41bb8b726315dfe1b731737e64e851cd4","source_id":"us-cfr","stale":true,"prev":"us/47-cfr-74.535","next":"us/47-cfr-74.537"},"notice":"GroundRules: Original legal text. Not legal advice."}