User's Manual

AR24027 Operator’s Manual (rev E)
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An additional increment must be added to the height of each obstruction because of the earth’s
curvature. For each obstruction calculate this increment using the following formula:
d =
d1
×
d2
×
C
K
Where:
(for US units:)
d = additional height increment in feet
d1 = distance of the obstruction from the first site in miles
d2 = distance of the obstruction from the second site in miles
C = .667 for US units
K = refractive index (use a value of 1.33).
(or for metric units:)
d = additional height increment in meters
d1 = distance of the obstruction from the first site in km
d2 = distance of the obstruction from the second site in km
C = .079 for metric units
K = refractive index (use a value of 1.33).
Add the “d” value to the height of each obstruction plotted on the graph.
Another increment must be added to the height of each obstruction because of the Fresnel zone (The
required increment is 60% of the first Fresnel zone radius). For each obstruction calculate the
increment using the formula:
d = C
d1
×
d2
F × D
Where:
(for US units:)
d = 60% of the first Fresnel zone radius in feet
d1 = distance of the obstruction from the first site in miles
d2 = distance of the obstruction from the second site in miles
C = 1368 for US units
F = 2400 (frequency in MHz)
D = total path length in miles (d1 + d2).
(or for metric units:)
d = 60% of the first Fresnel zone radius in meters
d1 = distance of the obstruction from the first site in km
d2 = distance of the obstruction from the second site in km
C = 259 for metric units
F = 2400 (frequency in MHz)
D = total path length in km (d1 + d2).
Add the “d” value to the height of each obstruction plotted on the graph.