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Installing VEGA Antenna for Optimal Results

Introduction

Cellular network operators, when building or enhancing their network coverage over open rural areas or long roads and highways, are looking for inexpensive means to extend the range of existing or planned BTS. The VEGA very high gain antenna can do the job in a most cost-effective way.
 
Although VEGA, having extremely high gain over common Omni or panel BTS antennas, can be a significant addition to the tool-box of the operator in his coverage design, it will need very accurate direction and tilt setting to exploit the high gain of the VEGA antenna.
 
This technical note presents the steps to be taken when a narrow beam VEGA is installed, either for trial or for permanent usage.

VEGA antenna accurate direction and tilt setting

 
VEGA line antennas are unique in their high gain. This high gain is a result of the VEGA’s very narrow focused beam.
This narrow beam nature of the VEGA antennas requires extremely accurate setting of the Vega's azimuth and down tilt. This is done by the same method narrow beam microwave link antennas are tuned to beam at the opposite companion antenna. 
Misalignment of azimuth and / or tilt can and will cause poor results and disappointment since with narrow beam antennas, any error, large or small, will result in signal degradation at the target area. 
Usual cellular BTS sector antenna installation and setting tools, like a compass, are not appropriate to directionally aligning the VEGA high gain narrow beam antenna.
 
The technician should use the same methods he would have used when directionally aligning a MW link antenna.

The following is to summarize the steps to be taken to tune VEGA properly:

 
1.  When installing the VEGA on the tower, first aim the tilt and azimuth to the required target by looking through the VEGA sighting tube and centering the sight tube on the target. (see figure 7.6 of the VEGA Installation Manual)
2.  Using the coverage simulation software, find the expected performance of the VEGA when directed at the required target area.
 
3.   If the target area is not clearly visible through the sight tube of the antenna, set the direction by a compass and inclination measurement tool.
 
4.    In any case, to make sure the antenna's azimuth and tilt are properly set to achieve maximum results from the VEGA antenna, an active setting is strongly recommended.
 
5. The following procedure will ensure your obtaining best results from the VEGA.
 
  1. Set the VEGA's azimuth and tilt as above.
  2. Make sure the technician on the tower remains with the antenna and is equipped with a cell phone or other means of communication with the technician in the drive test vehicle.
     
  3. Park the drive test vehicle at the center of your target area or on the side of the highway you need to cover at a median distance between the tower and the far limit of the section you wish to cover.
     
    It is important that the drive test vehicle is stationary and safely parked so that the signal received through the VEGA will be stable.
     
  4. While monitoring the received signal strength coming through the VEGA, instruct the technician on the tower, to change the tilt of the VEGA until the signal received is maximized. 
     
  5. Do the same for the VEGA direction by instructing the technician to change the direction of the antenna in very small steps until the signal strength of the VEGA is maximized. 
     
  6. The VEGA's azimuth and tilt should now be secured by locking the installation bolts.
     
  7. Do the full drive test at the target area or the selected highway section.
     

Another, perhaps more efficient, method of fine tuning the VEGA’s aim is to use the following procedure.

1. When installing the VEGA on the tower, first aim the tilt and direction to the required target by looking through theVEGA sight and centering the sight tube on the target (see figure 7.6 of the VEGA Installation Manual)
 
2. If the target area is not clearly visible through the sight tube of the antenna, set the direction by a compass and inclination measurement tool.
 
3. Set up a signal generator/transmitter in the center of the target area.
 
4. Connect a receiver/spectrum analyzer to the mounted, pre-aimed VEGA antenna connector.
 
5. Fine tune the aim of the VEGA in both azimuth & elevation axis until the measuring device shows the strongest signal received from the signal generator. Tighten all mounting and directing bolts.
 
6. Do the full drive test at the target area or the selected highway section.
Following these instructions closely will insure you are gaining maximum results and enjoying the benefits of using the VEGA very high gain narrow beam antenna. We welcome your comments and suggestions and will be happy to be at your service should you require our assistance.