Andrew 960 Class II Assembly Instructions Manual - Page 9

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POLARIZATION CHART

L" IS THE DIFFERENCE BETWEEN THE EARTH STATION

ANTENNA SITE LONGITUDE AND THE SATELLITE LONGITUDE

POLARIZATION CHART SIGN VALUES (+ OR -)

ANTENNA SITE WEST OF SATELLITE LONGITUDE

ANTENNA SITE EAST OF SATELLITE LONGITUDE

EARTH STATION LATITUDE IN DEGREES NORTH OR SOUTH OF EQUATOR

CHART 1

NORTHERN

SOUTHERN

HEMISPHERE

ANTENNA

—

FEED

Feed Rotation (Facing Antenna)

For + Polarization, Rotate CCW (Counter Clockwise)

For - Polarization, Rotate CW (Clockwise)

Alignment with the satellite is obtained by setting polariza-

tion, elevation and azimuth. Charts 1, 2 & 3 are to determine

these 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 THE FEED

Loosen Feed Horn Clamp Bolts and turn Feed clockwise or

counterclockwise, depending on being east or west of the

satellite as shown on Chart 1. For course setting, align

marks on the Horn Scale (Ref. Fig. 3.0). Polarization chart

assumes antenna system polarization is Tx vertical and

satellite vertical Pol is perpendicular to plane of geostation-

ary 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.) Use a signal

strength measuring device for final polarization setting and

tighten horn clamp bolts to 4 ft-lbs (5.4 N-m).

ELEVATION

Use Chart 2 and determine your elevation setting. Loosen

Elevation Pivot Bolts and Bolts in curved slots (both sides)

of AZ/EL housing approximately 1 complete turn (Ref. Fig.

3.1). Turn Elevation Adjustment Bolt clockwise to decrease

elevation and counterclockwise to increase elevation. Align

the edge of the Clamp with appropriate mark on housing at

the desired elevation reading. This will be an approximate

setting. Optimum setting achieved when fine tuning.

NOTE: Degree values shown on Elevation Scale are Beam;

there is no need to compensate for any offset angle. (See

Appendix A, Outline Drawing).If clinometer is used, you must

compensate for offset angle.

AZIMUTH

Use Chart 3 and determine your azimuth setting. Values in

chart must be adjusted for magnetic deviation for your loca-

tion for correct compass reading. Rotate Reflector and

Mount pointing it to the correct compass reading. Slowly

sweep the antenna in azimuth until signal is found. If the

desired signal is not found, increase or decrease elevation

setting and repeat the azimuth sweep (Ref. Fig. 3.2). Tighten

Half Clamp Bolts .

FINE TUNING

Use Signal Tuning Device for final adjustments to obtain

maximum antenna performance. Alternate between eleva-

tion and azimuth fine tuning to reach maximum signal

strength, until no improvement can be detected. Certain

models utilize the optional azimuth fine tune feature (refer to

Figure 3.2). This allows the azimuth to be fine tuned by loos-

ening the (4) Carriage Head Bolts and Swivel Nut which

allows adjusting the Azimuth Fine Tune Adjusting Bolt for the

peak signal. When fine tuning is complete, tighten and

torque all AZ/EL hardware to 12 ft-lbs (16.3 N-m). Do not

exceed 12 ft-lbs (16.3 N-m). Torque Clamp Hardware to 18

ft-lbs (24.4 N-m) in alternating sequence.

IMPORTANT: Recheck and repeat torque on four Clamp

Bolts, Fig. 3.1 in alternating sequence, until all Bolts are

equally torqued to 18 ft-lbs.

ANTENNA ALIGNMENT PROCEDURE

CLAMP BOLT

FIG. 3.0 - Polarization of the Feed

EDGE OF CLAMP

BRACKET

EXAMPLE:

18" ELEVATION

FIG. 3.1 - Setting the Elevation

AZIMUTH FINE TUNE

ADJUSTING BOLT

HEX NUT,

CARRIAGE BOLT (4)

HEX NUT,

SWIVEL NUT

FIG. 3.2 - Rotating Antenna for Azimuth

HORN SCALE

ALIGNMENT MARK

ELEVATION ADJUSTING

SCREW

CURVED SLOT BOLT

ELEVATION

PIVOT

BOLT

CLAMP BOLT

(4 PLCS)

AZIMUTH