DragonWave Horizon COMPACT - Detailed Alignment of the Horizon Compact Antennas

Aligning the Horizon Compact System
13
Horizon Compact Release 1.01.00 Wireless Ethernet Product User Manual – Volume 2
2.2 Detailed Alignment of the Horizon Compact Antennas
This section describes how to perform detailed alignment of the Horizon Compact antennas.
Note: The Horizon Compact BNC Field Strength connector serves two purposes. It is used for alignment
and for system redundancy purposes. When used for alignment it provides an output voltage of 1 mV DC
per dB of signal strength. Connecting a digital voltmeter to this connector will provide you with a
convenient way of measuring field strength and confirming antenna alignment. Use the CLI command set
alignment on press Enter, to enable the field strength measuring option. When used for redundancy
purposes ensure that the CLI command set alignment off is used.
The DragonWave Horizon Compact Web Interface may also be used for alignment. From the Home page,
select Tools, then Link Alignment. The RSL readings displayed are continuously updated and the highest
value reached is retained to facilitate the alignment procedure.
When you prepare to align the antennas, you must consider three important factors:
• The radiation pattern of the Horizon Compact antennas (main lobe and side
lobes)
1. The need for a Clear Line of Sight (LOS)
2. The sensitivity of the alignment adjustment. See Section
2.2.3 for more details.
Caution
Alignment of the Horizon Compact requires power to be supplied to the
PonE and surge protector unit.
Caution
Proper alignment results in increased signal quality! Once the Horizon
Compact units have been visually aligned, detailed alignment can begin.
Pan across the entire beamwidth to ensure the alignment corresponds to
the main lobe and not to a Side Lobe.
Caution
Transmission of radio signals results in a primary signal (main lobe) and
secondary signals (side lobes) being sent towards the destination.
During installation the side lobes can be mistaken for the main lobe,
resulting in a 20-30 dB loss of signal strength. On a 12” / 30 cm antenna,
the entire beamwidth typically lies within a 5–degree span so it is critical
to ensure alignment targets the main lobe and not the side lobes. Larger
antennas have a narrower beam. For a 24”/60 cm antenna, the entire
beamwidth lies within a 3–degree span.
Caution
It is possible to get a “peak” reading during the antenna alignment
process if one or both of the antennas is aligned on a side lobe. In such a
case, the measured receive level may be 20 dB or more lower than the
callculated value. Be aware that the link may still function under these
circumstances. If the readings are within 2 - 4 dB of the calculated levels,
then the antennas are most likely to be properly aligned.