StacksVerified U.S. regulatory reference

47 CFR §80.767

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
The propagation graph, § 80.767 Graph 1, must be used in computing the service area contour. The graph provides data for field strengths in dBu for an effective radiated power of 1 kW, over sea water, fresh water or land (smooth earth); transmitting antena heights of 4,800, 3,200, 1,600, 800, 400, 200, and 100 feet; based on a receiving antenna height of 9 meters (30 feet), for the 156-162 MHz band. The use of this is described in this section.
  1. (a)Calculate the effective radiated power of the coast station, Ps in dB referred to 1 kW (dBk), as follows:
  2. (b)Determine the antenna height. For antenna heights between the heights for which this graph is drawn, use linear interpolation; assume linear height-gain for antennas higher than 4,800 feet.
  3. (c)For receiver antenna heights lower than 9 meters (30 feet), assume that the field strength is the same as at 9 meters (30 feet).
  4. (d)Assume that propagation over fresh water or over land is the same as that over sea water.