§  73.1675   Auxiliary antennas.

   (a)(1) An auxiliary antenna is one that is permanently installed and
   available for use when the main antenna is out of service for repairs
   or replacement. An auxiliary antenna may be located at the same
   transmitter site as the station's main antenna or at a separate site.
   The service contour of the auxiliary antenna may not extend beyond the
   following corresponding contour for the main facility:

   (i) AM stations: The 0.5 mV/m field strength contours.

   (ii) FM stations: The 1.0 mV/m field strength contours.

   (iii) TV stations: The Grade B coverage contours.

   (iv) Class A TV stations: The protected contours defined in § 73.6010.

   (2) An application for an auxiliary antenna for an AM station filed
   pursuant to paragraphs (b) or (c) of this section must contain a map
   showing the 0.5 mV/m field strength contours of both the main and
   auxiliary facilities.

   (b) An application for a construction permit to install a new auxiliary
   antenna, or to make changes in an existing auxiliary antenna for which
   prior FCC authorization is required (see § 73.1690), must be filed on
   FCC Form 301 (FCC Form 340 for noncommercial educational stations).

   (c)(1) Where an FM, TV or Class A TV licensee proposes to use a
   formerly licensed main facility as an auxiliary facility, or proposes
   to modify a presently authorized auxiliary facility, and no changes in
   the height of the antenna radiation center are required in excess of
   the limits in § 73.1690(c)(1), the FM, TV or Class A TV licensee may
   apply for the proposed auxiliary facility by filing a modification of
   license application. The modified auxiliary facility must operate on
   the same channel as the licensed main facility. An exhibit must be
   provided with this license application to demonstrate compliance with
   § 73.1675(a). All FM, TV and Class A TV licensees may request a decrease
   from the authorized facility's ERP in the license application. An FM,
   TV or Class A TV licensee may also increase the ERP of the auxiliary
   facility in a license modification application, provided the
   application contains an analysis demonstrating compliance with the
   Commission's radiofrequency radiation guidelines, and an analysis
   showing that the auxiliary facility will comply with § 73.1675(a). Where
   an FM, TV, or Class A TV licensee or permittee proposes to mount an
   auxiliary facility on an AM tower, it must also demonstrate compliance
   with § 1.30003 in the license application.

   (2) Where an AM licensee proposes to use a former licensed main
   facility as an auxiliary facility with an ERP less than or equal to the
   ERP specified on the former main license, the AM station may apply to
   license the proposed auxiliary facility by filing a modification of
   license application on Form 302-AM. The proposed auxiliary facilities
   must have been previously licensed on the same frequency as the present
   main facility. The license application must contain an exhibit to
   demonstrate compliance with § 73.1675(a).

   [ 43 FR 53741 , Nov. 17, 1978, as amended at  44 FR 22740 , Apr. 17, 1979;
    45 FR 26066 , Apr. 17, 1980;  50 FR 13974 , Apr. 9, 1985;  62 FR 51060 ,
   Sept. 30, 1997;  63 FR 70049 , Dec. 18, 1998;  65 FR 30005 , May 10, 2000;
    78 FR 66298 , Nov. 5, 2013]