Sec.  21.904   EIRP limitations.

   

   (a) The maximum EIRP of a main or booster station shall not exceed 33
   dBW + 10log(X/6) dBW, where X is the actual bandwidth if other than 6
   MHz, except as provided in paragraph (b) of this section.

   (b)(i) If a main or booster station sectorizes or otherwise uses one
   or more transmitting antennas with a non-omnidirectional horizontal
   plane radiation pattern, the maximum EIRP in a given direction shall
   be determined by the following formula:

   EIRP = 33 dBW + 10 log(X/6) dBW + 10 log(360/beamwidth) dBW, where X
   is the channel width in MHz and 10 log(360/beamwidth) =< 6 dB.

   (ii) Beamwidth is the total horizontal plane beamwidth of the
   individual transmitting antenna for the station or any sector measured
   at the half-power points.

   (c) An increase in station EIRP, above currently-authorized or
   previously-proposed values, to the maximum values provided in
   paragraphs (a) and (b) of this section may be authorized, if the
   requested increase would not cause harmful interference to any
   authorized or previously-proposed, cochannel or adjacent channel
   station entitled to interference protection under the Commission's
   rules, or if an applicant demonstrates that:

   (1) A station that must be protected from interference could
   compensate for interference by increasing its EIRP; and

   (2) The interfered-with station may increase its own EIRP consistent
   with the rules and without causing harmful interference to any
   cochannel or adjacent channel main or booster station protected
   service area, response station hub or BTA/PSA, for which consent for
   the increased interference has not been obtained; and

   (3) The applicant requesting authorization of an EIRP increase agrees
   to pay all expenses associated with the increase in EIRP by the
   interfered-with station.

   (d) For television transmission if the authorized bandwidth is 4.0 MHz
   or more for the visual and accompanying aural signal, the peak power
   of the accompanying aural signal must not exceed 10 percent of the
   peak visual power of the transmitter. The Commission may order a
   reduction in aural signal power to diminish the potential for harmful
   interference.

   (e) For main, booster and response stations utilizing digital
   emissions with non-uniform power spectral density (e.g. unfiltered
   QPSK), the power measured within any 100 kHz resolution bandwidth
   within the 6 MHz channel occupied by the non-uniform emission cannot
   exceed the power permitted within any 100 kHz resolution bandwidth
   within the 6 MHz channel if it were occupied by an emission with
   uniform power spectral density, i.e., if the maximum permissible power
   of a station utilizing a perfectly uniform power spectral density
   across a 6 MHz channel were 2000 watts EIRP, this would result in a
   maximum permissible power flux density for the station of 2000/60 =
   33.3 watts EIRP per 100 kHz bandwidth. If a non-uniform emission were
   substituted at the station, station power would still be limited to a
   maximum of 33.3 watts EIRP within any 100 kHz segment of the 6 MHz
   channel, irrespective of the fact that this would result in a total 6
   MHz channel power of less than 2000 watts EIRP.

   [ 64 FR 63732 , Nov. 22, 1999]