Installation Manual Part 3

PRELIMINARY
6-19
BWX 8415 Basestation Installation and Commissioning Guide
OL-19519-01
Chapter 6 Installation
6.3.8 Antenna Orientation
Figure 6-19 Downtilt Adjustment Assembly
6.3.8 Antenna Orientation
The magnetic declination, which is the angular difference between observed magnetic north on a
compass and geographic (or “true”) north, shifts from year to year. Panel antennas must be oriented
appropriately as required by the RF plan.
Adjustments that will need to be made are based on the Magnetic Declination Chart (Figure 6-20), which
provides values to correct the compass reading and determine the true geographic East. Always check
for the latest chart information, which may be found at the following web address:
www.thecompassstore.com/decvar.html.
Since this is not the year 2000 any more, you will want to check this reference chart to learn how your
magnetic declination may have shifted since then. Notice that the map measures annual shifts in minutes.
Since it takes 60 minutes to equal 1 degree, if you notice that your location has a declination shift of 5
minutes per year, this means it will be another 12 years before your declination adjustment changes by
one whole degree.
Downtilt Adjustment
Bracket Bolts