Sec.  25.204   Power limits.

   (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) For operations at frequencies above 10 GHz, earth station operators may
   exceed the uplink e.i.r.p. and e.i.r.p. density limits specified in the
   station authorization under the 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. The
   e.i.r.p. levels shall be returned to normal as soon as the attenuating
   weather pattern subsides. The maximum power level for power control purposes
   shall be coordinated between and among adjacent satellite operators.

   (f) In the band 13.75–14 GHz, an earth station in the fixed-satellite
   service shall have a minimum antenna diameter of 4.5 m and the e.i.r.p. of
   any emission should be at least 68 dBW and should not exceed 85 dBW. The
   e.i.r.p. density of emissions from any earth station in the FSS operating
   with a space station in geostationary-satellite orbit shall not exceed 71
   dBW in any 6 MHz band from 13.77 to 13.78 GHz. The e.i.r.p. density of
   emissions from any earth station in the FSS operating with a space station
   in non-geostationary-satellite orbit shall not exceed 51 dBW in any 6 MHz
   band from 13.77 to 13.78 GHz. Automatic power control may be used to
   increase the e.i.r.p. density in the 6 MHz band in this frequency range to
   compensate for rain attenuation, to the extent that the power flux-density
   at the FSS space station does not exceed the value resulting from use by an
   earth station of an e.i.r.p. of 71 dBW or 51 dBW, as appropriate, in the 6
   MHz band in clear-sky conditions.

   (g) All earth stations in the Fixed Satellite Service in the 20/30 GHz band
   shall employ uplink adaptive power control or other methods of fade
   compensation such that the earth station transmissions shall be conducted at
   the power level required to meet the desired link performance while reducing
   the level of mutual interference between networks.

   (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  Sec. 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.

   [ 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]