DragonWave Horizon COMPACT Plus Product Manual page 72

DragonWave Inc.
62
11.2 Radio Frequency (RF) Alignment of the Antennas
This section describes how to perform the RF alignment of the Horizon Compact Plus systems antennas.
Note: The Horizon Compact Plus BNC Field Strength connector serves two purposes. It is used for RF
alignment and for system redundancy purposes. When used for RF 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 system RF alignment. Use the CLI
command set alignment on press Enter, to enable the field strength measuring option. When used for
redundancy purposes (not supported in this release) ensure that the CLI command set alignment off is
used.
The DragonWave Horizon Compact Plus Web Interface may also be used for RF 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 systems, you must consider the three important factors noted in Section
10.2 and repeated below:
1. The radiation pattern of the Horizon Compact Plus antennas (main lobe and side lobes)
2. The need for a Clear Line of Sight (LOS) and avoiding the Fresnel zone
3. The sensitivity of the alignment adjustment – one tenth of a turn at a time
Caution
Alignment of the Horizon Compact Plus requires power to be supplied to
the PonE and surge protector unit.
Caution
Proper alignment results in increased signal quality! Once the Horizon
Compact Plus 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
dish/reflector, 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 dish/reflectors have a narrower beam. For a 24"/60 cm
dish/reflector, the entire beamwidth lies within a 3–degree span.
Caution
It is possible to get a "peak" reading during the system alignment
process if one or both of the systems is aligned to 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 systems are most likely to be properly aligned.
Horizon Compact Plus Release 1.0.1
Wireless Ethernet Product User Manual – Volume 1