Sec. 25.209  Antenna performance standards.

    (a) The gain of any antenna to be employed in transmission from an 
earth station in the fixed-satellite service shall lie below the 
envelope defined below:
    (1) In the plane of the geostationary satellite orbit as it appears 
at the particular earth station location:
[GRAPHIC] [TIFF OMITTED] TC13NO91.008


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:

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    Outside the main beam, the gain of the antenna shall lie below the 
envelope defined by:
[GRAPHIC] [TIFF OMITTED] TC13NO91.009


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:
[GRAPHIC] [TIFF OMITTED] TC13NO91.010

    (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 routinely 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 deg. orbital spacings. An earth station antenna initially 
authorized on or before Feburary 15, 1985 will be authorized by the 
Commission to continue to operate as long as such operations are found 
not to cause any 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.
    (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 deg. instead of 1 deg. as stipulated in paragraph (a) 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]