CFR > Title 47 - Telecommunication > CHAPTER I—FEDERAL COMMUNICATIONS COMMISSION > SUBCHAPTER D—SAFETY AND SPECIAL RADIO SERVICES (Parts 80–101) > PART 101—FIXED MICROWAVE SERVICES > SUBPART C—Technical Standards (§101.101 to §101.151) > 101.143—Minimum path length requirements.

101.143—Minimum path length requirements.

(a) The distance between end points of a fixed link in the private operational fixed point-to-point and the common carrier fixed point-to-point microwave services 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 to 7,125 17
10,550 to 13,250 5
Above 17,700 N/A
(b) For paths shorter than those specified in the table in paragraph (a) of this section, 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 Section 101.113(a).
A = Minimum path length from the Table above for the frequency band in kilometers.
B = The actual path length in kilometers.

Code of Federal Regulations

Note 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.
(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.

Code of Federal Regulations

Code of Federal Regulations 672
Note to paragraph (c): Links authorized prior to April 1, 1987, need not comply with this requirement.
[61 FR 26677, May 28, 1996, as amended at 65 FR 38330, June 20, 2000]