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 § 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.
Code of Federal Regulations
Code of Federal Regulations
(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
[52 FR 7143, Mar. 9, 1987, as amended at 68 FR 12771, Mar. 17, 2003]