Sec.  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  Sec. 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  Sec. 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
    Sec. 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  Sec. 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  Sec. 73.1675(a). Auxiliary
   facilities mounted on an AM antenna tower must also demonstrate compliance
   with  Sec. 73.1692 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  Sec. 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]