Sec.  25.209   Antenna performance standards.

   (a) The gain of any antenna to be employed in transmission from an earth
   station in the geostationary satellite orbit fixed-satellite service (GSO
   FSS) shall lie below the envelope defined as follows:

   (1) In the plane of the geostationary satellite orbit as it appears at the
   particular earth station location:
   [MATH:  :MATH]

   where Theta is the angle in degrees from the axis of the main lobe, and dBi
   refers to dB relative to an isotropic radiator. For the purposes of this
   section, the peak gain of an individual sidelobe may not exceed the envelope
   defined above for Theta between 1.0 and 7.0 degrees. For Theta greater than
   7.0 degrees, the envelope may be exceeded by no more than 10% of the
   sidelobes, provided no individual sidelobe exceeds the gain envelope given
   above by more than 3 dB.

   (2) In all other directions, or in the plane of the horizon including any
   out-of-plane potential terrestrial interference paths:

   Outside the main beam, the gain of the antenna shall lie below the envelope
   defined by:
   [MATH:  :MATH]

   where Theta and dBi are defined above. For the purposes of this section, the
   envelope may be exceeded by no more than 10% of the sidelobes provided no
   individual sidelobe exceeds the gain envelope given above by more than 6 dB.
   The region of the main reflector spillover energy is to be interpreted as a
   single lobe and shall not exceed the envelope by more than 6 dB.

   (b) The off-axis cross-polarization gain of any antenna to be employed in
   transmission from an earth station to a space station in the domestic
   fixed-satellite service shall be defined by:
   [MATH:  :MATH]

   (c) Earth station antennas licensed for reception of radio transmissions
   from a space station in the fixed-satellite service are protected from radio
   interference caused by other space stations only to the degree to which
   harmful interference would not be expected to be caused to an earth station
   employing an antenna conforming to the referenced patterns defined in
   paragraphs (a) and (b) of this section, and protected from radio
   interference caused by terrestrial radio transmitters identified by the
   frequency coordination process only to the degree to which harmful
   interference would not be expected to be caused to an earth station
   conforming to the reference pattern defined in paragraph (a)(2) of this
   section.

   (d) The patterns specified in paragraphs (a) and (b) of this section shall
   apply to all new earth station antennas initially authorized after February
   15, 1985 and shall apply to all earth station antennas after March 11, 1994.

   (e) The operations of any earth station with an antenna not conforming to
   the standards of paragraphs (a) and (b) of this section shall impose no
   limitations upon the operation, location or design of any terrestrial
   station, any other earth station, or any space station beyond those
   limitations that would be expected to be imposed by an earth station
   employing an antenna conforming to the reference patterns defined in
   paragraphs (a) and (b) of this section.

   (f) An earth station with an antenna not conforming to the standards of
   paragraphs (a) and (b) of this section will be authorized after February 15,
   1985 upon a finding by the Commission that unacceptable levels of
   interference will not be caused under conditions of uniform 2 ° orbital
   spacing. An earth station antenna initially authorized on or before February
   15, 1985 will be authorized by the Commission to continue to operate as long
   as such operations are found not to cause unacceptable levels of adjacent
   satellite interference. In either case, the Commission will impose
   appropriate terms and conditions in its authorization of such facilities and
   operations. The applicant has the burden of demonstrating that its antenna
   not conforming to the standards of paragraphs (a) and (b) of this section
   will not cause unacceptable interference. This demonstration must comply
   with the procedures set forth in  Sec. 25.220.

   (g) The antenna performance standards of small antennas operating in the
   12/14 GHz band with diameters as small as 1.2 meters starts at 1.25 ° instead
   of 1 ° as stipulated in paragraph (a) of this section.

   (h)(1) The gain of any antennas to be employed in transmission from a
   gateway earth station antenna operating in the frequency bands 10.7–11.7
   GHz, 12.75–13.15 GHz, 13.2125–13.25 GHz, 13.8–14.0 GHz, and 14.4–14.5 GHz
   and communicating with NGSO FSS satellites shall lie below the envelope
   defined as follows:

   29 − 25log[10] (Θ) dBi − 10 dBi

   1^B ≤ Θ ≤ 36^B

   36^B ≤ Θ ≤ 180^B

   Where: Θ is the angle in degrees from the axis of the main lobe, and dBi
   refers to dB relative to an isotropic radiator.

   (2) For the purposes of this section, the peak gain of an individual
   sidelobe may not exceed the envelope defined in paragraph (h)(1) of this
   section.

   [ 48 FR 40255 , Sept. 6, 1983, as amended at  50 FR 2675 , Jan. 18, 1985;  50 FR 39004 , Sept. 26, 1985;  58 FR 13420 , Mar. 11, 1993;  66 FR 10630 , Feb. 16,
   2001;  70 FR 32255 , June 2, 2005]