alignment of the microwave antennas

5/26/2018 Alignment of the Microwave Antennas

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HUAWEI TECHNOLOGIES CO., LTD.

www.huawei.com

Huawei Confidential

Security Level:Nov 12, 2008

Alignment of

Microwave Antennas


www.huawei.com

Wang Fuzhong

Transmission Engineering Dept.


2/29HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 2

Contents

1. Resources and Tools Required for the Antenna Alignment

2. Precautions for Installing the Microwave Equipment

3. Commissioning Preparations

4. Precautions for the Alignment

5. Method for Adjusting the Antenna Support

6. Procedure for Aligning the Antennas

7. Resolution for Aligning the Antennas

8. Method for Aligning Antennas in HSB/SD/FD Modes

9. Checking After the Alignment



Resources and Tools Required for the

Antenna Alignment

Design document: Includes the site information file and basic data files.

Assembly personnel required: four. Two persons are assigned at each site.

Multimeters required (which works better with the BNC connecter): two. One

multimeter is provided at each site.

Portable computers required: One. The computers are used to configure the

radio transmission network (RTN) equipment and to check the received

signal level (RSL).

Telecommunication tool: includes interphones and mobile phones.

Spanner

Telescope

Magnetic compass



Prerequisites for Installing the MicrowaveEquipment

The microwave equipment must be ready for the telecom (RFT) test.

Security check must be conducted.

The antenna must be installed and the outdoor operations must be

performed. These operations must be performed in favorable weather.

The IF cable and the elliptical wavelength must be installed.

The indoor operations, which can be performed during unfavorable

weather and at night, must be performed.

All the cables and links must be labelled.

Grounding must be performed.

The installation field must be cleaned after the installation is complete.

The power-on operation must be performed.



Commissioning Preparations

1. According to the network planning document, check the service

capacity and modulation scheme of the IF board, and check whether the

transmit frequency and power of the ODU are consistent with the actual

configuration of the NE.

2. Set the working attribute of the ODU to Transmit.

3. Disable the ATPC function.

4. In the case of 1+1 protection configuration, set the working attribute of

the standby ODU to Muteor Forcibly Switched to the Working Board.

5. Check the alarms of the ODU. Normally, only the alarms indicating

that the RSL of the ODU is excessively low are reported.



Precautions for the Alignment

Grease the nuts so that the antenna can be aligned smoothly and stably. Align the antenna slowly. A delay may be caused in responding to the

equipment due to a change in the RSL.

When aligning the local antenna, make sure that the elevation and azimuth of

the antenna are locked. Do not align the antennas at both ends at the same

time.

When aligning the azimuth, make sure that the elevation of the local antenna

is locked.

When aligning the elevation, make sure that the azimuth of the local antenna

is locked.

Do not fasten the antenna very tightly before the alignment is complete. when

you move the antenna, do not apply too much force. Otherwise, the antennamay be damaged mechanically.


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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 7

Method of Adjusting the Antenna Support

(With a Diameter of 0.3 M, 0.6 M)

You can adjust the elevation of the antenna at point 1, and the azimuth of the antenna at point 2.


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Method of Adjusting the Antenna Support(With a Diameter of 1.2 M)

You can adjust the azimuth of the antenna by moving the support at point 1, and the elevation

of the antenna at point 2.


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Method of Adjusting the Antenna Support(with a Diameter of 1.2 M)

Over-head view at point 2


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Procedure for Aligning the Antennas

Step 1 If the distance between the two antennas is more than 2 km, place

the two antennas horizontally. If the distance between the two antennas is

no more than 2 km, slightly adjust the elevation of the antenna according

to the actual situation.

Step 2 Connect the multimeter to the port of the local ODU correctly. Then,

measure the VBNC

of the RSSI port.

Step 3 Adjust the azimuth of the antenna.

1. Keep the opposite antenna fixed.

2. Measure the VBNCby using the multimeter. Move the antenna from left to right

and make sure that the antenna tracks at least three peak signals of the VBNC. The

voltage of the second peak signal should be the maximum one.


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Step 3 Adjust the elevation of the antenna.

1. Adjust the elevation at each peak VBNCso that the VBNCcan reach themaximum value.

2. Adjust the antenna to a position where the VBNCreaches the highest

value. Then, fix the local antenna. Make sure that the VBNCis of the

maximum value when the antenna is fixed.

Step 4Repeat Steps 2 and 3 to adjust the antenna on the opposite side.After the RSL of the opposite antenna reaches the maximum value, fix

the opposite antenna.


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Step 5 Repeat Steps 24 two to four times to make the receive

signal levels at both ends reach the maximum value. Then, fix

the antennas at both ends.

Step 6Measure the VBNC at both ends by using the multimeter.

Obtain the current RSL by referring to the curve diagram and

the RSL of the VBNC of the ODUs at both ends.

Step 7Fasten all the screws of the antenna.


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Resolution for Aligning the Antennas

1. Coarse Adjustment

Lock the antenna at one side and loosen the adjusting nut of

the antenna at the other side. According to the network

planning design, adjust the azimuth and elevation of the

antennas so that the antennas at both ends can be aligned.

The RSL is about 80 dB. When one antenna is adjusted, the

other antenna is locked. That is, the antennas at both ends

are adjusted alternatively.


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Adjusting the Antenna by Using the MultimeterCorrectly connect the multimeter to the received signal strength indicator (RSSI)

port of the local ODU. Set the multimeter to 10 V DC. Measure the VBNC of this

port.


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Resolution for Aligning the AntennasThe VBNC of the RSSI port varies directly with the RSL of the antenna corresponding to the

ODU. That is, the higher the RSL, the higher is the VBNC. Adjustthe antenna until the voltagereaches the peak value so that the main lobes can be aligned properly. The following curve

figure shows the relationship between the VBNC and the RSL.

-100 -90 -80 -70 -60 -50 -40 -30 -20 -100

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

RSL(dBm)

RSSIVoltage(V)


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Keep the opposite antenna fixed. The local antenna moves left to right at different elevations. Measurethe VBNC. Lines AA, BB, and CC are different tracking paths of the antenna. According to the

corresponding VBNC change curve, you can learn that line AA is the path wherein the main lobes of the

antennas are aligned properly. Three points reach the peak value on the curve. The main lobe is at point

2. The first side lobes are at points 1 and 3.

Tracking path at different

elevations

VBNCchanges during the

path tracking


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Resolution for Aligning the Antennas (Vertically)

Lateral viewMain lobeMain lobe

First side lobe


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Resolution for Aligning the Antennas (Vertical

Alignment)

Ground or mirror reflection

Not aligned vertically



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Resolution for Aligning the Antennas (Vertical

Alignment)

Aligned properly



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Resolution for Aligning the Antennas (Special Adjustment in

the Case of Multipath Fading Caused by the Reflection During

the Long-Distance Transmission)

Aligned properly


After the antennas are aligned properly, raise the elevation of theantennas slightly (by 0.35 to 0.5 degrees, depending on the FNBW). In

this manner, the multipath fading caused by the reflection during the

long-distance transmission over the water surface is reduced.


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Resolution for Aligning the Antennas (Horizontally)

Vertical view

Main lobeMain lobe

First side lobe

R l ti f Ali i th A t (H i t l


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Resolution for Aligning the Antennas (Horizontal

Alignment)

Not aligned properly Aligned properly


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2. Small Adjustment

The adjustment sequence is not required. If you adjust the elevation first, fix the

opposite antenna, and adjust the local antenna. Adjust the nuts to search for the peak

value S0. When the peak value S0 appears, continue to adjust the nuts until the peak

value S1 appears. If S1 is more than S0, continue to adjust the nuts in the same

direction until the peak signal S2 appears. If S2 is less than S1, S1 is the required point.

If S1 is less than S0, you must adjust the nuts in the opposite direction. Now, go back to

point S0, and continue to adjust the nuts until the next peak signal S-1 appears. If S-1 is

less than S0, S0 is the required point. If S-1 is more than S0, continue to adjust the nuts

until the next peak signal S-2 appears. If S-2 is less than S-1, S-1 is the required point.

During the adjustment, you need to find three continuous peak signals, and the peak

signal at the middle point must reach the largest value. In this case, the middle point is

the required point. Adjust the azimuth by using the same method. After the local

antenna is adjusted, fix the local antenna, and adjust the opposite antenna. Only several

adjustments are required to align the antennas properly.


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RSSI/VAGC

First side lobe

Main lobe

Align the antennas by referring to the VBNC of the RSSI port.

According to the envelope diagram of the antenna radiation,

you can learn that the signals reach three peak values duringthe antenna adjustment. One peak signal appears when the

main lobes of the two antennas are aligned properly. The other

peak signals appear when the main lobe of the local antenna is

aligned with both the first side lobes of the opposite antenna.

The peak signal reaches the highest peak value when the main

lobes of the two antennas are aligned properly.


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HSB Protection Mode

The main and standby ODUs share one antenna.

You only need to adjust the main ODU. If the

microwave link uses the 1+1 protection scheme

wherein one antenna is used. Power off the

standby ODUs at both ends before aligning the

antennas. After aligning the antennas, power on

the standby ODUs at both ends.


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FD Protection Mode

If one antenna is used, you only need to adjust the main ODU. If

two antennas are used, you need to adjust both the antennas.

The adjustment sequence is as follows:

(1) Power off the standby ODUs at both ends, and then align

the main antennas at both ends.

(2) Power on the standby ODUs at both ends, and then align

the standby antennas at both ends.


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SD Protection ModeAfter aligning the main antennas, you need to check whether the RSL of the

standby ODUs is almost the same as the RSL of the main ODUs. After

aligning the standby antennas, you need to check whether the RSL of the

main ODUs is almost the same as the RSL of the standby ODUs. Ensure that

the RSL of the main ODU and the RSL of the standby ODU at the opposite

end are almost the same, regardless of whether the main ODU or the standby

ODU is used.

The adjustment sequence is as follows:

(1) Power off the standby ODUs at both ends, and then align the main

antennas at both ends.

(2) Power on the standby ODUs at the local end, and then fix the main

antenna at the opposite end, and adjust the diversity antenna at the local end.


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Checking After the Alignment

1. Set the ATPC to Disabledaccording to the network planning.

2. If the 1+1 protection scheme is configured, set the working

attribute of the main ODU and standby ODU to Unmute.

3. If the 1+1 protection scheme is configured and the service isbeing switched, clear the switching so that the main ODUs at both

ends are used.

4. Check the alarms, and ensure that no alarm is reported.


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www.huawei.com

Huawei Confidential

Security Level:Nov 12, 2008

Thank you !

www.huawei.com

alignment of the microwave antennas

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