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 1,990        n/a
         1,990–7,125         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 = MAXEIRP−40 log(A/B) dBW

   Where:

   EIRP = The new maximum EIRP (equivalent isotropically radiated power) in
   dBW.

   MAXEIRP = Maximum EIRP as set forth in the Table in  Sec. 74.636 of this part.

   A = Minimum path length from the Table above for the frequency band in
   kilometers.

   B = The actual path length in kilometers.

   Note 1 to paragraph(b): For transmitters using Automatic Transmitter Power
   Control, EIRP corresponds to the maximum transmitter power available, not
   the coordinated transmit power or the nominal transmit power.

   Note 2 to paragraph(b): Stations licensed based on an application filed
   before  April  16,  2003, in the 2450–2483.5 MHz band, for EIRP values
   exceeding those specified above, may continue to operate indefinitely in
   accordance  with the terms of their current authorizations, subject to
   periodic renewal.

   (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, as amended at  68 FR 12771 , Mar. 17, 2003]