Sec. 74.641 Antenna systems.
(a) For fixed stations operating between 1990 MHz and 31.3 GHz and
aeronautical mobile stations operating between 31.0 GHz and 31.3 GHz,
the following standards apply:
(1) Fixed TV broadcast auxiliary stations shall use directional
antennas that meet the performance standards indicated in the following
table. Upon adequate showing of need to serve a larger sector, or more
than a single sector, greater beamwidth or multiple antennas may be
authorized. Applicants shall request, and authorization for stations in
this service will specify, the polarization of each transmitted signal.
Booster station antennas having narrower beamwidths and reduced sidelobe
radiation may be required in congested areas, or to resolve interference
problems.
(i) Stations must employ an antenna that meets the performance
standards for Category B. In areas subject to frequency congestion,
where proposed facilities would be precluded by continued use of a
Category B antenna, a Category A antenna must be employed. The
Commission may require the use of a high performance antenna where
interference problems can be resolved by the use of such antennas.
(ii) Licensees shall comply with the antenna standards table shown
in this paragraph in the following manner:
(A) With either the maximum beamwith to 3 dB points requirement or
with the minimum antenna gain requirement; and
(B) With the minimum radiation suppression to angle requirement.
Antenna Standards
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Maximum Min
imum radiation suppression to angle in degrees from
beamwidth
centerline of main beam in decibels
to 3 dB Minimum ---------
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Frequency (MHz) Category points 1 antenna
(included gain 5 deg.
10 deg. 15 deg. 20 deg. 30 deg. 100 deg. 140 deg.
angle in (dbi) to 10
to 15 to 20 to 30 to 100 to 140 to 180
degrees) deg.
deg. deg. deg. deg. deg. deg.
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1,990 to 2,110....................................... A
B 5.0
8.0 n/a
n/a 12
5
18
18 22
20 25
20 29
25 33
28 39
36
6,875 to 7,125....................................... A
B 1.5
2.0 n/a
n/a 26
21
29
25 32
29 34
32 38
35 41
39 49
45
12,700 to 13,250..................................... A
B 1.0
2.0 n/a
n/a 23
20
28
25 35
28 39
30 41
32 42
37 50
47
17,700 to 19,700..................................... A
B 2.2
2.2 38
38 25
20
29
24 33
28 36
32 42
35 55
36 55
36
31,000 to 31,300 2................................... n/a 3 4.0 38
n/a n/a n/a n/a n/a n/a n/a
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1 If a licensee chooses to show compliance using maximum beamwith to 3 dB points, the beamw
idth limit shall apply in both the azimuth and the elevation
planes.
2 Mobile, except aeronautical mobile, stations need not comply with these standards.
3 The minimum front-to-back ratio shall be 38 dBi.
(2) New periscope antenna systems will be authorized upon a
certification that the radiation, in a horizontal plane, from an
illuminating antenna and reflector combination meets or exceeds the
antenna standards of this section. This provision similarly applies to
passive repeaters employed to redirect or repeat the signal from a
station's directional antenna system.
(3) The choice of receiving antennas is left to the discretion of
the licensee. However, licensees will not be protected from interference
which results from the use of antennas with poorer performance than
identified in the table of this section.
[[Page 423]]
(4) [Reserved]
(5) Pickup stations are not subject to the performance standards
herein stated. The provisions of this paragraph are effective for all
new applications accepted for filing after October 1, 1981.
(b) Any fixed station licensed pursuant to an application accepted
for filing prior to October 1, 1981, may continue to use its existing
antenna system, subject to periodic renewal until April 1, 1992, After
April 1, 1992, all licensees are to use antenna systems in conformance
with the standards of this section. TV auxiliary broadcast stations are
considered to be located in an area subject to frequency congestion and
must employ a Category A antenna when:
(1) A showing by an applicant of a new TV auxiliary broadcast
station or Cable Television Relay Service (CARS) station, which shares
the 12.7-13.20 GHz band with TV auxiliary broadcast, indicates that use
of a category B antenna limits a proposed project because of
interference, and
(2) That use of a category A antenna will remedy the interference
thus allowing the project to be realized.
(c) As an exception to the provisions of this section, the FCC may
approve requests for use of periscope antenna systems where a persuasive
showing is made that no frequency conflicts exist in the area of
proposed use. Such approvals shall be conditioned to a standard antenna
as required in paragraph (a) of this section when an applicant of a new
TV auxiliary broadcast or Cable Television Relay station indicates that
the use of the existing antenna system will cause interference and the
use of a category A or B antenna will remedy the interference.
(d) As a further exception to the provision of paragraph (a) of this
section, the Commission may approve antenna systems not conforming to
the technical standards where a persuasive showing is made that:
(1) Indicates in detail why an antenna system complying with the
requirements of paragraph (a) of this section cannot be installed, and
(2) Includes a statement indicating that frequency coordination as
required in Sec. 74.604 (a) was accomplished.
[ 45 FR 78693 , Nov. 26, 1980, as amended at 49 FR 7131 , Feb. 27, 1984; 49 FR 37778 , Sept. 26, 1984; 50 FR 7342 , Feb. 22, 1985; 51 FR 19840 , June
3, 1986; 52 FR 7143 , Mar. 9, 1987; 55 FR 11587 , Mar. 29, 1990; 56 FR 50663 , Oct. 8, 1991; 62 FR 4922 , Feb. 3, 1997]