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42S042D
e.
To determine the azimuth aiming coordinate for the antenna,
follow the curved lines upward and estimate where the reference
point determined in (b) above would intersect the upper edge of
the graph. The example is about 242°.
5.
When using a compass to locate the azimuth aiming coordinate
determined in step 4.e above, it may be necessary to adjust the
compass indication (because of magnetic deviation) before pointing
the antenna. In the example, the azimuth angle is 242°; however,
from Figure 2-4, Atlanta, Georgia, is about +1° of magnetic deviation
from true North. Therefore, to compensate for deviation, add 1° to
our azimuth calculation: 242° + 1° = 243°, which is the actual
compass reading to use in pointing the antenna.
The above method should be used in determining the antenna
aiming coordinates for both the satellite(s) from which
reception is currently desired and for satellite(s) from which
reception may be desired in the future.
Azimuth and elevation aiming coordinates may also be determined by
formula using a digital calculator. In these formulas, X represents the
site latitude in degrees, Y represents the site longitude in degrees, and
Z represents the satellite longitude in degrees. For the southern
hemisphere, enter X as negative. If west longitudes are entered as
positive numbers, define the longitude difference as:
D = Z - Y
If East longitudes are entered as positive numbers, define the
longitude difference as:
D = Y - Z
The constant K is defined as:
K =
Compute the elevation angle E and the azimuth angle A according to
the following formulas:
−
E
tan
=
A = tan
If X>0 (i.e., a northern hemisphere latitude), then add 180° to A to
get the angle from true north. Then add the appropriate magnetic
deviation angle as described before to obtain the compass heading.
SERIES 8060 6-METER EARTH STATION ANTENNA
ANTENNA SITE SELECTION (120° AND 180° ANTENNA)
NOTE
1
6.611
cos
D x
cos
X
−
1
2
(
sin
D
)
(
cos
D x
+
tan D
-1
sin X
K
2
sin
X
)
2-6
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