Lynx.GX Installation and Management
Mounting the Antenna
This section describes how to permanently mount the antenna to the mast, pole, or tower, and how to attach the
antenna to the RFU.
The antenna must be mounted outdoors on a tower, building roof, or other location that provides line-of-sight
path clearance to the far-end location. In general, antennas smaller than two feet in diameter, or one-foot
panels, are not recommended for use with these radios.
Antennas should be:
▪
Ordered with the suitable mounting kit specific to the site requirements.
▪
Very rigidly mounted, with adequate room for azimuth and elevation adjustment from the rear.
The antenna polarization must be the same at both ends of the link, either
vertical
or
horizontal
.
In general, antenna mountings require a support pipe to which upper and lower support brackets are attached
with U-bolts. The antenna and optional elevation and azimuth adjustment rods then are mounted onto the
support brackets. The entire structure must be adequately grounded for lightning protection (see “Grounding”
on page 27). The antenna system must always be installed according to the manufacturer's instructions.
Unless special test equipment is available, two operating radios are required to align the antennas.
Alternatively, you can use a CW generator to transmit a signal toward the end being aligned.
The antenna is coarse-aligned using visual sighting and then fine-aligned using the receive signal level (RSL)
voltage provided by the radio.
The RSL voltage reading still can be used to peak antennas even if the wireless units have not synchronized;
however, you cannot measure far-end RSL from the near-end terminal until the units are synchronized.
Aligning the Antenna
The larger the antenna, the more critical alignment becomes. For example, with a 2-foot dish at 5.8 GHz, the
antenna can be moved ±3 degrees off the correct heading before the receive signal level drops by 3 dB. This
compares with a 6-foot dish, which can be moved only ±1 degree for the same degradation.
▪
You must perform antenna alignment on one end of the link at a time, one plane at a time.
▪
Keep one antenna stationary at all times.
▪
Fine-align each end several times, until the planned RSL is reached.
In some cases, you may need to perform coarse alignment using a wide arc in both azimuth and elevation while
reading the RSL to find the main beam of the opposite end antenna.
Note:
The RSL voltage is slightly delayed, so make small incremental adjustments during the fine alignment
phase and wait a few seconds for the RSL voltage to settle after each adjustment. When aligned to
maximum RSL, ensure that all antenna mechanics are tightened without impacting the alignment.
Coarse Alignment
To coarse-align the antenna, set the antenna mount for flat elevation (no up-tilt or down-tilt) using a spirit level.
Point the antenna at a heading marker obtained using a compass/GPS (magnetic corrected) back-bearing from
an adjacent location (ideally, 100 feet or more away from the antenna).
If the path has substantial change to elevation from one end to the other, this may not be an advisable method
for starting the alignment activities. In such cases, compare antenna elevations at each end of the link and set
the initial elevation of the antenna to roughly match the anticipated up-tilt or down-tilt.
Chapter 2. Installing the IDU and RFU
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