§ 25.210   Technical requirements for space stations.

   (a) All space stations in the Fixed-Satellite Service used for domestic
   service in the 3700-4200 MHz and 5925-6425 MHz frequency bands shall:

   (1) Use orthogonal linear polarization with one of the planes defined by the
   equatorial plane;

   (2) Be designed so that the polarization sense of uplink transmissions is
   opposite to that of downlink transmissions on the same transponder; and

   (3) Shall be capable of switching polarization sense upon ground command.

   (b) [Reserved]

   (c) Space station antennas operating in the Direct Broadcast Satellite
   Service or operating in the Fixed-Satellite Service for reception of feeder
   links for Direct Broadcast Satellite Service must be designed to provide a
   cross-polarization isolation such that the ratio of the on-axis co-polar
   gain to the cross-polar gain of the antenna in the assigned frequency band
   is at least 27 dB within the primary coverage area.

   (d)-(e) [Reserved]

   (f) All space stations in the Fixed-Satellite Service operating in any
   portion of the 3600-4200 MHz, 5091-5250 MHz, 5850-7025 MHz, 10.7-12.7 GHz,
   12.75-13.25 GHz, 13.75-14.5 GHz, 15.43-15.63 GHz, 18.3-20.2 GHz, 24.75-25.25
   GHz,  or  27.5-30.0  GHz bands, including feeder links for other space
   services, and in the Broadcasting-Satellite Service in the 17.3-17.8 GHz
   band (space-to-Earth), shall employ state-of-the-art full frequency reuse,
   either through the use of orthogonal polarizations within the same beam
   and/or the use of spatially independent beams. This requirement does not
   apply to telemetry, tracking, and command operation.

   (g)-(h) [Reserved]

   (i)(1) Space station antennas in the Fixed-Satellite Service, other than
   antennas  in  the  17/24  GHz  BSS,  must  be  designed  to  provide a
   cross-polarization isolation such that the ratio of the on axis co-polar
   gain to the cross-polar gain of the antenna in the assigned frequency band
   shall be at least 30 dB within its primary coverage area.

   (2) Space station antennas in the 17/24 GHz Broadcasting Satellite Service
   must be designed to provide a cross-polarization isolation such that the
   ratio of the on axis co-polar gain to the cross-polar gain of the antenna in
   the assigned frequency band shall be at least 25 dB within its primary
   coverage area.

   (j) Space stations operated in the geostationary satellite orbit must be
   maintained within 0.05° of their assigned orbital longitude in the east/west
   direction, unless specifically authorized by the Commission to operate with
   a  different longitudinal tolerance, and except as provided in Section
   25.283(b) (End-of-life Disposal).

   [ 58 FR 13420 , Mar. 11, 1993, as amended at  61 FR 9952 , Mar. 12, 1996;  62 FR 5931 , Feb. 10, 1997;  62 FR 61457 , Nov. 18, 1997;  68 FR 51508 , Aug. 27, 2003;
    69 FR 54587 , Sept. 9, 2004;  70 FR 32256 , June 2, 2005;  72 FR 50029 , Aug. 29,
   2007;  78 FR 8428 , Feb. 6, 2013;  79 FR 8323 , Feb. 12, 2014]

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