7
ANTENNA ALIGNMENT PROCEDURE
Alignment with the satellite is obtained by setting
polarization, elevation, and azimuth. Charts 1, 2 & 3 are
to determine the values for your earth station antenna
site. “
∆
L” is the difference between the earth station
antenna site longitude and the satellite longitude. Use
“
∆
L” and your earth station latitude to obtain polarization,
elevation or azimuth setting.
POLARIZATION OF FEED
Loosen feed horn clamp bolts and turn feed clockwise or
counterclockwise, depending on being east or west of
the satellite as shown in Chart 1. Align marks on the horn
clamp and appropriate mark on the horn scale.
Polarization chart assumes antenna system polarization
is Tx vertical and satellite vertical Pol is perpendicular to
plane of geostationary arc. For horizontal Tx of antenna,
feed must be rotated 90˚ from values shown. (Starting
point for polarization adjustment is 0˚, as shown in
Figure 3.0).
ELEVATION ADJUSTMENT
Use Chart 2 and determine your elevation setting. Using
a clinometer, adjust the elevation by turning the elevation
screw adjusting nuts until the desired elevation is
obtained. Reference Figure 3.1. Note: Degree values
shown on the clinometer are mechanical; that is
when the reflector face is vertical mechanical
elevation is 90˚ or axis is 0˚, while the beam elevation
(signal) axis is 22.62˚. Therefore as the reflector is
tilted, remember to compensate for the 22.62˚ offset
angle to get the correct beam elevation.
(See Appendix A, Outline Drawing, Page 14). This is
an approximate setting. Optimum setting will be achieved
during the fine tuning.
HORN SCALE
ALIGNMENT MARK
+40
0
-40
CLAMP BOLT
PIVOT
BOLT
(LOOSEN)
ELEVATION
BOLT
(LOOSEN)
ELEVATION
ADJUSTING
SCREW
TRUNNION
CLINOMETER
ELEVATION
HEX NUTS
RIB
FIGURE - 3.0
FIGURE - 3.1
