§  73.62   Directional antenna system operation and tolerances.

   (a) Each AM station operating a directional antenna must maintain the
   relative amplitudes of the antenna currents, as indicated by the
   antenna monitor, within 5% of the values specified on the instrument of
   authorization. Directional antenna relative phases must be maintained
   within 3 degrees of the values specified on the instrument of
   authorization.

   (b) In the event of a failure of system components, improper pattern
   switching or any other event that results in operation substantially at
   variance from the radiation pattern specified in the instrument of
   authorization for the pertinent time of day, operation must be
   terminated within three minutes unless power can be reduced
   sufficiently to eliminate any excessive radiation. See § 73.1350(e).

   (1) Any variation of operating parameters by more than ±15 percent
   sample current ratio or ±10 degrees in phase, any monitor point that
   exceeds 125 percent of the licensed limit, or any operation at variance
   that results in complaints of interference shall be considered
   operation substantially at variance from the license and will require
   immediate corrective action.

   (2) [Reserved]

   (c) In the event of minor variations of directional antenna operating
   parameters from the tolerances specified in paragraph (a) of this
   section, the following procedures will apply:

   (1) The licensee shall measure and log every monitoring point at least
   once for each mode of directional operation. Subsequent variations in
   operating parameters will require the remeasuring and logging of every
   monitoring point to assure that the authorized monitoring point limits
   are not being exceeded. The licensee will be permitted 24 hours to
   accomplish these actions; provided that, the date and time of the
   failure to maintain proper operating parameters have been recorded in
   the station log.

   (2) Provided each monitoring point is within its specified limit,
   operation may continue for a period up to 30 days before a request for
   Special Temporary Authority (STA) must be filed, pursuant to paragraph
   (c)(4) of this section, to operate with parameters at variance from the
   provisions of paragraph (a) of this section.

   (3) If any monitoring point exceeds its specified limit, the licensee
   must either terminate operation within three hours or reduce power in
   accordance with the applicable provisions of § 73.1350(d), in order to
   eliminate any possibility of interference or excessive radiation in any
   direction.

   (4) If operation pursuant to paragraph (c)(3) of this section is
   necessary, or before the 30-day period specified in paragraph (c)(2) of
   this § expires, the licensee must request a Special Temporary Authority
   (STA) in accordance with section 73.1635 to continue operation with
   parameters at variance and/or with reduced power along with a statement
   certifying that all monitoring points will be continuously maintained
   within their specified limits.

   (d) In any other situation in which it might reasonably be anticipated
   that the operating parameters might vary out of tolerance (such as
   planned array repairs or adjustment and proofing procedures), the
   licensee shall, before such activity is undertaken, obtain a Special
   Temporary Authority (STA) in accordance with § 73.1635 in order to
   operate with parameters at variance and/or with reduced power as
   required to maintain all monitoring points within their specified
   limits.

   [ 72 FR 44422 , Aug. 8, 2007]