Maintenance Manual

INSTALLATION AND MAINTENANCE MANUAL
Tsunami FAMILY
FAST ETHERNET WIRELESS BRIDGES
SEPTEMBER 1999
PAGE 3-18 SECTION 3: INSTALLATION & ADJUSTMENTS
3.10 Antenna Installation & Alignment
The antenna installation consists of permanently mounting the antenna 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 2 feet diameter are not recommended for urban areas due to their
wider beamwidths, which results in higher interference susceptibility.
Antennas should be ordered with a suitable mounting kit specific to the site requirements. For
example, specifying round or angle tower leg adapters, or a roof tripod as necessary.
The antenna must be 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 are
then mounted onto the support brackets. The whole structure must be adequately grounded for
lightning protection. The antenna system must always be installed according to the manufacturer’s
instructions.
Unless special test equipment is available, two operating Tsunami terminals are required to align
the antennas. Alternatively, a CW generator may be used to transmit a signal toward the end
under alignment.
The antenna is coarse aligned using visual sighting and then fine aligned using the receive signal
level (RSL) voltage of the Tsunami.
The RSL voltage reading can still be used to peak antennas
even if the radios have not synchronized, however far-end RSL
cannot be measured from the near-end terminal until radios
are synchronized.
To coarse align the antenna, first set it for flat elevation (no up or down tilt) using a spirit level.
Then point it at a heading marker obtained using a compass back-bearing from an adjacent
location, (ideally, 100 feet or more away from the antenna).
If a heading marker cannot be set sufficiently far away (for example when on a city building roof or
looking through a window) then a rough azimuth setting can be obtained by sighting along the
antenna feed.
Due to the possibility of exposure to RF radiation above the recommended
levels, do not stand within five (5) feet of the antenna during system
operation. It is the responsibility of the installer to insure that the antenna is
fix-mounted in a place that is not accessible to the public and not pointed in
a direction where human exposure may exceed these recommendations.