Sec. 74.536  Directional antenna required.

    (a) Aural broadcast STL and ICR stations are required to use a 
directional antenna with the minimum beamwidth necessary, consistent 
with good engineering practice, to establish the link.
    (b) An aural broadcast STL or intercity relay station operating in 
the 17.7-19.7 GHz band shall employ an antenna that meets the 
performance standards for Category A, except that in areas not subject 
to frequency congestion, antennas meeting standards for Category B may 
be employed. However, the Commission may require the replacement, at the 
licensee's expense, of any antenna or periscope antenna system of a 
permanent fixed station that does not meet performance Standard A, which 
is specified in the table in paragraph (c) of this section, upon a 
showing that said antenna causes or is likely to cause interference to 
(or receive interference from) any other authorized or proposed station; 
provided that an antenna meeting performance Standard A is unlikely to 
involve such interference.
    (c) 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           
                                                        
------------------------------------------------------------------------------------------------
--------------------------------------------------------
                                                                   Maximum                   Min
imum radiation suppression to angle in degrees from     
                                                                  beamwidth                     
       centerline of main beam in decibels              
                                                                   to 3 dB    Minimum  ---------
--------------------------------------------------------
                   Frequency (GHz)                      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.  
------------------------------------------------------------------------------------------------
--------------------------------------------------------
17.7 to 19.7.........................................          A                                
                                                        
                                                               B        2.2                     
                                                        
                                                                        2.2         38          
                                                        
                                                                                    38      25  
                                                        
                                                                                            20  
     29                                                 
                                                                                                
     24       33                                        
                                                                                                
              28       36                               
                                                                                                
                       32        42                     
                                                                                                
                                 35        55           
                                                                                                
                                           36        55 
                                                                                                
                                                     36 
31.0 to 31.3 2.......................................        n/a      3 4.0         38
     n/a      n/a      n/a      n/a       n/a       n/a       n/a 
------------------------------------------------------------------------------------------------
--------------------------------------------------------
1 If a licensee chooses to show compliance using maximum beamwidth to 3 dB points, the beam
width 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.                                         
                                                             

[ 48 FR 50333 , Nov. 1, 1983, as amended at  49 FR 7130 , Feb. 27, 1984;  50 FR 48599 , Nov. 26, 1985;  51 FR 19840 , June 3, 1986;  62 FR 4922 , Feb. 3, 
1997]

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