RDL-2000
Installation Guidelines
70-00144-01-01
Proprietary Redline Communications © 2011
Page
47
of 52
March 9, 2011
4.6 Step 6: Antenna Alignment
4.6.1 Basic Antenna Alignment
Correct antenna alignment is essential in obtaining the maximum performance from the
wireless link. A misaligned antenna will result in decreased receive signal strength and
you may be unable to establish the wireless link.
The alignment must be performed in both the azimuth and elevation planes. Before
installing the equipment, obtain accurate antenna pointing azimuth and elevation angles
for each installation site (see section 0:
Site Survey Information on page 12). This will allow approximate alignment of antennas
by using GPS or magnetic compass.
Antenna Polarization
The same antenna polarization must be used for both RDL-2000 units in a SISO (single
antenna system) PTP link. The arrows on the rear of the antenna indicate the
polarization.
Azimuth Alignment
Use a magnetic or GPS compass to obtain the approximate azimuth direction. Note that
a metal tower will affect the accuracy of a magnetic compass. Magnetic declination (the
difference between true North and Magnetic North) must also be taken onto account.
The azimuth is aligned by loosening the bolts on the pipe bracket and rotating the
antenna around the pole. To adjust the azimuth, loosen the four bolts identified in the
figure on this page.
Elevation Alignment
Most links will have an elevation of zero degrees. The antenna can be set vertically (to a
close approximation) using a bubble (spirit) level. This method is not accurate for
elevation settings of greater than 5 degrees.
To adjust the elevation, loosen the four bolts identified in the figure on this page.
4.6.2 Fine Antenna Alignment Using RSSI
The RDL-2000 must be connected to the Ethernet PoE adapter and configured before
the antenna alignment can be completed.
Antenna adjustments can also be made based on RSSI measurements reported by the
RDL-2000. The RSSI information is available using the built in audible antenna
alignment tool (Buzzer) or using the Link Manager application.
Slowly adjust the antenna elevation, and then azimuth in a broad sweeping pattern,
while observing the peaks and valleys in the RSSI readings.
While sweeping the antenna, the RSSI value will rise when aligned to a sidelobe, and
then fall and rise to the highest reading when the receiver is properly aligned to the main
beam. Further movement of the antenna will cause the RSSI to fall and then rise to a
lower peak when aligned to another sidelobe.
4Gon www.4Gon.co.uk [email protected] Tel: +44 (0)1245 808295 Fax: +44 (0)1245 808299
