Alignment of Microwave Antennas for Digital Microwave Transmission Systems
This article contains generic instructions for alignment of Microwave antennas. Specific products may have different features, in which case please refer to the documentation provided for those products:
Antenna Alignment for Microwave Links
This guide explains how to achieve the optimal antenna alignment of microwave antennas when used with modern digital microwave products. Before attempting to do the alignment it is highly recommended that you read this guide in detail. For specific commands please consult the manual of the product being installed
Step 1: Preparation:
Mount the antenna on the tower according to the antenna installation instructions: Ensure that the adjustment bolts move smoothly and the range of motion is sufficient for the expected angle of up and down (elevation) tilt. Ensure that the mount itself is attached securely and all safety precautions have been taken.
Step 2: Coarse Alignment:
Visually align the antenna with the far end. The most common ways to do this are :
1) If the visibility is good and the sun is in the correct position, have someone at the far end location reflect the sun with a mirror so the location is obvious.
2) If visibility is poor, use GPS coordinates and a GPS compass to aim the antenna coarsely.
Step 3: Fine Alignment.
Before conducting fine alignment, the ODUs at both ends of the link must be attached properly to the antenna via the direct mount or remote mount (using Waveguide) and the far end ODU must be powered on and transmitting. The ODU lightning surge suppressors and grounding provisions should be put in place as well before alignment. The local ODU must be powered on, but need not be transmitting.
1) Frequency of the far end transmitter matches the frequency of the local receiver.
2) The TX output power is not set above the level of the license.
3) ATPC is turned OFF on the far end.
4) Alignment mode is ON for SP ODUs – Display on ODU and IDU will update at 5 times per second.
FINE ALIGNMENT PROCEDURE
1) Adjust the azimuth over a 30 degree sweep by turning the adjustment bolt in increments of 1/10th turn to avoid missing the main lobe. When the highest signal has been found for azimuth, repeat for the elevation adjustment.
2) Turn the local transmitter on to allow alignment at the far end.
3) Move to the far end of the link and repeat step 1.
4) Lock down the antenna so no further movement can occur.
5) Install the antenna side struts supplied with the antenna.
6) Verify the RSSI remains the same and is within 2-4 dB of the expected levels.
7) Check the ODU connector seals.
8) Turn alignment mode OFF
9) The alignment is complete.