Proxim Wireless U5358-45 User Manual Modified pages of manual regarding RF exposure warning

Proxim Wireless Corporation Modified pages of manual regarding RF exposure warning

Contents

Modified pages of manual regarding RF exposure warning

INSTALLATION AND MAINTENANCE MANUAL
Tsunami FAMILY
FAST ETHERNET WIRELESS BRIDGES
December, 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.
INSTALLER CAUTION: Antennas used for this device must be fix-mounted
on permanent outdoor structures to provide 5 feet or more separation from
all persons during device operation to comply with FCC RF exposure
requirements. Installers should contact manufacturer for applicable gain and
type restrictions to ensure compliance.
INSTALLATION AND MAINTENANCE MANUAL
Tsunami FAMILY
FAST ETHERNET WIRELESS BRIDGES
December, 1999
PAGE 3-19 SECTION 3: INSTALLATION & ADJUSTMENTS
It should be verified that both antennas are on the same
polarization by using the manufacturer’s instructions. Otherwise
the RSL will be approximately 25 to 30 dB below the calculated
level.
Most antennas will also need fine alignment obtained using an operating link because it is very
important to maximize the receive RF signal level at each end of the radio link.
Read Section 3.7 before applying DC power to the Tsunami radio.
Once the coarse alignment has been set-up at both ends, then the link can be powered and some
level of reliable communication established. The voltage at the Tsunami front panel RSL test point
should be measured with a DVM to determine the relative receive RF signal level.
For the fine alignment, adjusting first the azimuth and then the elevation of the local antenna will
maximize the RSL voltage. Then, the far antenna is aligned in the same way, using the RSL
voltage of its local Tsunami radio.
When aligning antennas it may be convenient to run two wires from the RSL and ground test
points to the antenna so that the voltmeter reading is directly visible to the technicians aligning the
antenna. Also, a cellular telephone or two-way radio may be useful for coordinating alignment
activities between both ends of the link. Once the radios are coarse aligned and synchronized, the
built-in orderwire phone service can also be used to coordinate alignment between both ends of
the link.
An orderwire telephone will provide end-to-end voice
communications once radios are synchronized. Synchronization
usually can be accomplished by coarse alignment only. After
synchronization, the orderwire phones can be used to communicate
between radio sites for antenna fine alignment. The phone
interconnect cable can be extended to the antenna when desired.
The larger the antenna size, the more critical alignment becomes: for example, with a 2 foot dish,
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 may only be moved ±1 degree for the
same degradation.
The graph shown in Figure 3-6 shows the typical variation of RSL voltage as the receive signal
level is increased from threshold to a higher level. There is some variation between Tsunami
receivers, but an approximate estimate of the potential RSL value may be made using this figure.

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