Sec.  101.115   Directional antennas.

   (a) Unless otherwise authorized upon specific request by the applicant, each
   station authorized under the rules of this part must employ a directional
   antenna adjusted with the center of the major lobe of radiation in the
   horizontal  plane  directed toward the receiving station with which it
   communicates: provided, however, where a station communicates with more than
   one  point,  a multi- or omni-directional antenna may be authorized if
   necessary.  New  Periscope  antenna  systems  will not, under ordinary
   circumstances, be authorized.

   (b) Fixed stations (other than temporary fixed stations and DEMS nodal
   stations) operating at 932.5 MHz or higher must employ transmitting and
   receiving antennas (excluding second receiving antennas for operations such
   as space diversity) meeting the appropriate performance Standard A indicated
   below, except that in areas not subject to frequency congestion, antennas
   meeting performance Standard B may be used, subject to the requirements set
   forth in paragraph (d) of this section. Licensees shall comply with the
   antenna standards table shown in this paragraph in the following manner:

   (1) With either the maximum beamwidth to 3 dB points requirement or with the
   minimum antenna gain requirement; and

   (2) With the minimum radiation suppression to angle requirement.

   Antenna Standards
   Frequency (MHz) Category Maximum beamwidth to 3 dB points^1(included angle
   in degrees) Minimum antenna gain (dbi) Minimum radiation suppression to
   angle in degrees from centerline of main beam in decibels
   5 ° to10 ° 10 ° to 15 ° 15 ° to 20 ° 20 ° to 30 ° 30 ° to 100 ° 100 ° to 140 ° 140 ° to
   180 °
   932.5 to 935 A 14.0 n/a n/a 6 11 14 17 20 24
      B 20.0 n/a n/a n/a 6 10 13 15 20
   941.5 to 944 A 14.0 n/a n/a 6 11 14 17 20 24
      B 20.0 n/a n/a n/a 6 10 13 15 20
   952 to 960^2,3 A 14.0 n/a n/a 6 11 14 17 20 24
      B 20.0 n/a n/a n/a 6 10 13 15 20
   1,850 to 2,500^4 A 5.0 n/a 12 18 22 25 29 33 39
      B 8.0 n/a 5 18 20 20 25 28 36
   3,700 to 4,200 A 2.7 36 23 29 33 36 42 55 55
      B 2.7 36 20 24 28 32 32 32 32
   5,925 to 6,425^5 A 2.2 38 25 29 33 36 42 55 55
      B 2.2 38 21 25 29 32 35 39 45
   5,925 to 6,425^6 A 2.2 38 25 29 33 36 42 55 55
      B 2.2 38 20 24 28 32 35 36 36
   6,525 to 6,875^5 A 2.2 38 25 29 33 36 42 55 55
      B 2.2 38 21 25 29 32 35 39 45
   6,525 to 6,875^6 A 1.5 n/a 26 29 32 34 38 41 49
      B 2.0 n/a 21 25 29 32 35 39 45
   10,550 to 10,680^7 A 3.5 33.5 18 24 28 32 35 55 55
      B 3.5 33.5 17 24 28 32 35 40 45
   10,565 to 10,615 n/a 360 n/a n/a n/a n/a n/a n/a n/a n/a
   10,630 to 10,680^8 n/a 3.5 34 20 24 28 32 35 36 36
   10,700–11,700^5 A 2.2 38 25 29 33 36 42 55 55
   B 3.5 33.5 17 24 28 32 35 40 45
   12,200 to 13,250^9 A 1.0 n/a 23 28 35 39 41 42 50
      B 2.0 n/a 20 25 28 30 32 37 47
   17,700 to 18,820 A 2.2 38 25 29 33 36 42 55 55
      B 2.2 38 20 24 28 32 35 36 36
   18,920 to 19,700^10 A 2.2 38 25 29 33 36 42 55 55
      B 2.2 38 20 24 28 32 35 36 36
   21,200 to 23,600^7,11 A 3.3 33.5 18 26 26 33 33 55 55
      B 3.3 33.5 17 24 24 29 29 40 50
   24,250 to 25,250^10 A 2.8 38 25 29 33 36 42 55 60
      B 2.8 38 20 24 28 32 35 36 45
   31,000 to 31,300^12,13 n/a 4.0 38 n/a n/a n/a n/a n/a n/a n/a
   38,600 to 40,000^14 A n/a 38 25 29 33 36 42 55 55
      B n/a 38 20 24 28 32 35 36 36
   71,000 to 76,000 (co-polar)^15 N/A 1.2 43 35 40 45 50 50 55 55
   71,000 to 76,000 (cross-polar)^15 N/A 1.2 43 45 50 50 55 55 55 55
   81,000 to 86,000 (co-polar)^15 N/A 1.2 43 35 40 45 50 50 55 55
   81,000 to 86,000 (cross-polar)^15 N/A 1.2 43 45 50 50 55 55 55 55
   92,000 to 95,000 N/A 0.6 50.0 36 40 45 50 55 55 55

   ^1If a licensee chooses to show compliance using maximum beamwidth to 3 dB
   points,  the  beamwidth  limit shall apply in both the azimuth and the
   elevation planes.

   ^2Except for Multiple Address System frequencies listed in  Sec.  Sec. 101.147(b)(1)
   through (b)(4), where omnidirectional antennas may be used.

   ^3Antennas used at outlying stations as part of a central protection alarm
   system need conform to only the following 2 standards:

   (i) The minimum on-beam forward gain must be at least 10 dBi, and

   (ii) The minimum front-to-back ratio must be at least 20 dB.

   ^4Omnidirectional antennas may be authorized in the band 2150–2160 MHz.

   ^5These antenna standards apply to all point-to-point stations authorized
   after June 1, 1997. Existing licensees and pending applicants on that date
   are grandfathered and need not comply with these standards.

   ^6These antenna standards apply to all point-to-point stations authorized on
   or before June 1, 1997.

   ^7Except for antennas between 140 ° and 180 ° authorized or pending on January
   1,  1989, in the band 10,550 to 10,565 MHz for which minimum radiation
   suppression  to  angle (in degrees) from centerline of main beam is 36
   decibels.

   ^8These antenna standards apply only to DEMS User Stations licensed, in
   operation, or applied for prior to July 15, 1993.

   ^9Except for Temporary-fixed operations in the band 13200–13250 MHz with
   output powers less than 250 mW and as provided in  Sec. 101.147(q), and except
   for antennas in the MVDDS service in the band 12.2–12.7 GHz.

   ^10DEMS User Station antennas in this band must meet performance Standard B
   and have a minimum antenna gain of 34 dBi. The maximum beamwidth requirement
   does not apply to DEMS User Stations. DEMS Nodal Stations need not comply
   with these standards. Stations authorized to operate in the 24,250–25,250
   MHz band do not have to meet these standards, however, the Commission may
   require the use of higher performance antennas where interference problems
   can be resolved by the use of such antennas.

   ^11Except as provided in  Sec. 101.147(s).

   ^12The minimum front-to-back ratio shall be 38 dBi.

   ^13Mobile, except aeronautical mobile, stations need not comply with these
   standards.

   ^14Stations authorized to operate in the 38,600–40,000 MHz band may use
   antennas other than those meeting the Category A standard. However, the
   Commission  may  require  the use of higher performance antennas where
   interference problems can be resolved by the use of such antennas.

   ^15Antenna gain less than 50 dBi (but greater than or equal to 43 dBi) is
   permitted only with a proportional reduction in maximum authorized EIRP in a
   ratio of 2 dB of power per 1 dB of gain, so that the maximum allowable EIRP
   (in dBW) for antennas of less than 50 dBi gain becomes +55−2(50–G), where G
   is the antenna gain in dBi. In addition, antennas in these bands must meet
   two  additional standards for minimum radiation suppression: At angles
   between 1.2 and 5 degrees from the centerline of the main beam, co-polar
   discrimination must be G−28, where G is the antenna gain in dBi; and at
   angles of less than 5 degrees from the centerline of main beam, cross-polar
   discrimination must be at least 25 dB.

   (c) The Commission shall require the replacement of any antenna or periscope
   antenna system of a permanent fixed station operating at 932.5 MHz or higher
   that does not meet performance Standard A specified in paragraph (c) of this
   section, at the expense of the licensee operating such antenna, upon a
   showing that said antenna causes or is likely to cause interference to (or
   receive interference from) any other authorized or applied for station
   whereas  a  higher  performance  antenna is not likely to involve such
   interference. Antenna performance is expected to meet the standards of
   paragraph  (c) of this section for parallel polarization. For cases of
   potential interference, an antenna will not be considered to meet Standard A
   unless the parallel polarization performance for the discrimination angle
   involved meets the requirements, even if the cross-polarization performance
   controls the interference.

   (d) In cases where passive reflectors are employed in conjunction with
   transmitting antenna systems, the foregoing paragraphs of this section also
   will be applicable. However, in such instances, the center of the major lobe
   of radiation from the antenna normally must be directed at the passive
   reflector, and the center of the major lobe of radiation from the passive
   reflector directed toward the receiving station with which it communicates.

   (e) Periscope antennas used at an electric power facility plant area will be
   excluded  from  the requirements of paragraph (c) of this section on a
   case-by-case basis where technical considerations or safety preclude the use
   of other types of antenna systems.

   (f) In the 10,700–11,700 MHz band, a fixed station may employ transmitting
   and receiving antennas meeting performance standard B in any area. If a
   Fixed Service or Fixed Satellite Service licensee or applicant makes a
   showing that it is likely to receive interference from such fixed station
   and that such interference would not exist if the fixed station used an
   antenna meeting performance standard A, the fixed station licensee must
   modify  its  use. Specifically, the fixed station licensee must either
   substitute an antenna meeting performance standard A or operate its system
   with an EIRP reduced so as not to radiate, in the direction of the other
   licensee, an EIRP in excess of that which would be radiated by a station
   using a Category A antenna and operating with the maximum EIRP allowed by
   the rules. A licensee or prior applicant using an antenna that does not meet
   performance Standard A may object to a prior coordination notice based on
   interference only if such interference would be predicted to exist if the
   licensee or prior applicant used an antenna meeting performance standard A.

   (g) In the event harmful interference is caused to the operation of other
   stations, the Commission may, after notice and opportunity for hearing,
   order changes to be made in the height, orientation, gain and radiation
   pattern of the antenna system.

   [ 61 FR 26677 , May 28, 1996, as amended at  62 FR 4924 , Feb. 3, 1997;  62 FR 24582 , May 6, 1997;  63 FR 6105 , Feb. 6, 1998;  65 FR 38329 , June 20, 2000;  65 FR 59358 , Oct. 5, 2000;  67 FR 43038 , June 26, 2002;  68 FR 4957 , Jan. 31,
   2003;  69 FR 3267 , Jan. 23, 2004;  70 FR 29997 , May 25, 2005;  72 FR 55677 ,
   Oct. 1, 2007;  73 FR 55775 , Sept. 26, 2008]