§ 25.204   Power limits for earth stations.

   (a) In bands shared coequally with terrestrial radio communication
   services, the equivalent isotropically radiated power transmitted in
   any direction towards the horizon by an earth station, other than an
   ESV, operating in frequency bands between 1 and 15 GHz, shall not
   exceed the following limits except as provided for in paragraph (c) of
   this section:

   + 40 dBW in any 4 kHz band for θ ≤0°

   + 40 + 3θ dBW in any 4 kHz band for 0° <θ ≤5°

   where θ is the angle of elevation of the horizon viewed from the center
   of radiation of the antenna of the earth station and measured in
   degrees as positive above the horizontal plane and negative below it.

   (b) In bands shared coequally with terrestrial radiocommunication
   services, the equivalent isotropically radiated power transmitted in
   any direction towards the horizon by an earth station operating in
   frequency bands above 15 GHz shall not exceed the following limits
   except as provided for in paragraph (c) of this section:

   + 64 dBW in any 1 MHz band for θ ≤0°

   + 64 + 3 θ dBW in any 1 MHz band for 0° <θ ≤5°

   where θ is as defined in paragraph (a) of this section.

   (c) For angles of elevation of the horizon greater than 5° there shall
   be no restriction as to the equivalent isotropically radiated power
   transmitted by an earth station towards the horizon.

   (d) Notwithstanding the e.i.r.p. and e.i.r.p. density limits specified
   in the station authorization, each earth station transmission shall be
   conducted at the lowest power level that will provide the required
   signal quality as indicated in the application and further amended by
   coordination agreements.

   (e) To the extent specified in paragraphs (e)(1) through (e)(3) of this
   section, earth stations in the Fixed-Satellite Service may employ
   uplink adaptive power control or other methods of fade compensation to
   facilitate transmission of uplinks at power levels required for desired
   link performance while minimizing interference between networks.

   (1) Except when paragraphs (e)(2) through (e)(3) of this section apply,
   transmissions from FSS earth stations in frequencies above 10 GHz may
   exceed the uplink EIRP and EIRP density limits specified in the station
   authorization under conditions of uplink fading due to precipitation by
   an amount not to exceed 1 dB above the actual amount of monitored
   excess attenuation over clear sky propagation conditions. EIRP levels
   must be returned to normal as soon as the attenuating weather pattern
   subsides.

   (2) An FSS earth station transmitting to a geostationary space station
   in the 13.77-13.78 GHz band must not generate more than 71 dBW EIRP in
   any 6 MHz band. An FSS earth station transmitting to a
   non-geostationary space station in the 13.77-13.78 GHz band must not
   generate more than 51 dBW EIRP in any 6 MHz band. Automatic power
   control may be used to increase the EIRP density in a 6 MHz uplink band
   in this frequency range to compensate for rain fade, provided that the
   power flux-density at the space station does not exceed the value that
   would result when transmitting with an EIRP of 71 dBW or 51 dBW, as
   appropriate, in that 6 MHz band in clear-sky conditions.

   (3) FSS earth stations transmitting to geostationary space stations in
   the 24.75-25.25 GHz, 28.35-28.6 GHz, and/or 29.25-30.0 GHz bands may
   employ uplink adaptive power control or other methods of fade
   compensation. For stations employing uplink power control, the values
   in paragraphs (a)(1), (2), and (4) of § 25.138 may be exceeded by up to
   20 dB under conditions of uplink fading due to precipitation. The
   amount of such increase in excess of the actual amount of monitored
   excess attenuation over clear sky propagation conditions must not
   exceed 1.5 dB or 15 percent of the actual amount of monitored excess
   attenuation in dB, whichever is larger, with a confidence level of 90
   percent except over transient periods accounting for no more than 0.5
   percent of the time during which the excess is no more than 4.0 dB.

   (f) An earth station in the Fixed-Satellite Service transmitting in the
   13.75-14 GHz band must have a minimum antenna diameter of 4.5 m, and
   the EIRP of any emission in that band should be at least 68 dBW and
   should not exceed 85 dBW.

   (g) [Reserved]

   (h) ESV transmissions in the 5925-6425 MHz (Earth-to-space) band shall
   not exceed an e.i.r.p. spectral density towards the radio-horizon of 17
   dBW/MHz, and shall not exceed an e.i.r.p. towards the radio-horizon of
   20.8 dBW. The ESV network shall shut-off the ESV transmitter if the
   e.i.r.p. spectral density towards the radio-horizon or e.i.r.p. towards
   the radio-horizon are exceeded.

   (i) Within 125 km of the TDRSS sites identified in § 25.222(d), ESV
   transmissions in the 14.0-14.2 GHz (Earth-to-space) band shall not
   exceed an e.i.r.p. spectral density towards the horizon of 12.5
   dBW/MHz, and shall not exceed an e.i.r.p. towards the horizon of 16.3
   dBW.

   (j) Within 125 km of the Tracking and Data Relay System Satellite
   (TDRSS) sites identified in § 25.226(c), VMES transmissions in the
   14.0-14.2 GHz (Earth-to-space) band shall not exceed an EIRP spectral
   density towards the horizon of 12.5 dBW/MHz, and shall not exceed an
   EIRP towards the horizon of 16.3 dBW.

   (k) Within radio line-of-sight of the Tracking and Data Relay System
   Satellite (TDRSS) sites identified in § 25.227(c), ESAA transmissions in
   the 14.0-14.2 GHz (Earth-to-space) band shall not exceed an EIRP
   spectral density towards or below the horizon of 12.5 dBW/MHz, and
   shall not exceed an EIRP towards or below the horizon of 16.3 dBW.

   [ 48 FR 40255 , Sept. 6, 1983, as amended at  58 FR 13420 , Mar. 11, 1993;
    61 FR 52307 , Oct. 7, 1996;  62 FR 61457 , Nov. 18, 1997;  66 FR 10623 ,
   Feb. 16, 2001;  70 FR 4784 , Jan. 31, 2005;  70 FR 32255 , June 2, 2005;  72 FR 50029 , Aug. 29, 2007;  74 FR 57098 , Nov. 4, 2009;  78 FR 8427 , Feb. 6,
   2013;  78 FR 14927 , Mar. 8, 2013;  79 FR 8322 , Feb. 12, 2004;  81 FR 55336 , Aug. 18, 2016;  83 FR 34491 , July 20, 2018]

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