Sec. 74.644  Minimum path lengths for fixed links.

    (a) The distance between end points of a fixed link must equal or 
exceed the value set forth in the table below or the EIRP must be 
reduced in accordance with the equation set forth below.

                                                                        
------------------------------------------------------------------------
           Frequency band (MHz)               Minimum path length (km)  
------------------------------------------------------------------------
below 1,850...............................  n/a                         
1,850--2,110..............................  17                          
6,425--7,125..............................  17                          
12,200--13,250............................  5                           
above 17,700..............................  n/a                         
------------------------------------------------------------------------

    (b) For paths shorter than those specified in the Table, the EIRP 
shall not exceed the value derived from the following equation.

EIRP=30--20 log [A/B], dBW

    where:
EIRP=equivalent isotropic radiated power in dBW.
A=Minimum path length from the Table for the frequency band in 
          kilometers.
B=The actual path length in kilometers.

    (c) Upon an appropriate technical showing, applicants and licensees 
unable to meet the minimum path length requirement may be granted an 
exception to these requirements.

    Note: Links authorized prior to April 1, 1987, are excluded from 
this requirement, except that, effective April 1, 1992, the Commission 
will require compliance with the criteria where an existing link would 
otherwise preclude establishment of a new link.


[ 52 FR 7143 , Mar. 9, 1987]