Andrew 123 Antenna Alignment Procedure, 0 - Polarization of the Feed, 1 - Setting the Elevation

POLARIZATION CHART

ANTENNA ALIGNMENT PROCEDURE

" L" IS THE DIFFERENCE BETWEEN THE EARTH STATION ANTENNA SITE LONGITUDE AND THE SATELLITE LONGITUDE

		NORTHERN	SOUTHERN
90	POLARIZATION CHART SIGN VALUES (+ OR -)	HEMISPHERE	HEMISPHERE
	ANTENNA SITE WEST OF SATELLITE LONGITUDE	-	+
	ANTENNA SITE EAST OF SATELLITE LONGITUDE	+	-

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ANTENNA

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. “ΔL” is the difference between the earth station antenna site longitude and the satellite longitude. Use “ΔL” 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

HORN SCALE

CLAMP BOLT ALIGNMENT MARK

FIG. 3.0 - Polarization of the Feed

	70
		+	—
ILLUSTRATION)			FEED
	60
		Feed Rotation (Facing Antenna)
		For + Polarization, Rotate CCW (Counter Clockwise)
	50	For - Polarization, Rotate CW (Clockwise)
— (SEE
		75O
OR

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.

EDGE OF CLAMP

BRACKET

EXAMPLE:

18" ELEVATION

ELEVATION ADJUSTING

SCREW

CURVED SLOT BOLT

ELEVATION

PIVOT

BOLT

CLAMP BOLT

(4 PLCS)

+	40					60O
POLARIZATION
					40O
	30				30O
					20O
				15O
	20
				10O
			5O
	10
	0
	0	10	20	30	40	50	60	70	80

EARTH STATION LATITUDE IN DEGREES NORTH OR SOUTH OF EQUATOR

CHART 1

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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.

FIG. 3.1 - Setting the Elevation

AZIMUTH FINE TUNE

ADJUSTING BOLT

HEX NUT,

CARRIAGE BOLT (4)

HEX NUT,

AZIMUTH

SWIVEL NUT

FIG. 3.2 - Rotating Antenna for Azimuth

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