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RF-8000E Operations Manual
Chapter 3. Mounting the Antennas — 43
Chapter 3. Mounting the Antennas
Mount Antennas
Mount all antennas, antenna feedlines, grounding, dehydration, and lightning protection. Test the
completed antenna system installation prior to repeater equipment installation. Follow details of the
site plan if available.
Antenna Types
Microwave RF repeaters can use any one of four typical parabolic antenna types:
Standard performance, single or dual polarized.
Improved performance, single or dual polarized
(Deep Dish, PAR, or PAD)
.
High Performance, single or dual polarized.
Ultra-High Performance, single or dual polarized.
NOTE: Antenna type is normally determined by the system requirements, especially the repeater site
antenna isolation objective for the radio system modulation. More complex modulations
require greater Carrier to Echo, C/E and hence, greater isolation. Repeater system path
calculations, path data sheet, are used to determine the antenna size and type.
Mount the antennas securely on adequate mounting structures. Mounting structures must meet
strength, twist and sway requirements for 8 GHz antenna systems. Provide means for alignment
adjustments.
Antenna Alignment
Coarse Alignment
To initially orient the antennas:
1. Align the “bore-sight” of the antenna to the calculated azimuth as shown in the site layout or path
calculations. Be sure to account for geomagnetic declination when using a magnetic compass.
Azimuths are normally shown as True North. Geomagnetic declination varies by site location and
typically drifts every year as the location of the earth’s magnetic pole moves.
2. Adjust the elevation to match the calculated elevation angle.
Fine Alignment using test radios
3. Peninsula Engineering recommends using test radios
to do the alignment over the hop. This is
much easier than attempting to use the limited repeater level indications or measurements. The
test radios also provide a talk channel to allow the alignment teams to rapidly communicate with
each other.
4. Identify the polarization determined for the hop. Consult the antenna manufacturer’s
documentation on identifying the vertical or horizontal antenna port on dual polarized antennas or
how the feed assembly is installed and oriented in single (plane) polarized antennas. Failure to
properly identify polarizations will result in antenna misalignment and violate the station license.
5. Attach the test radios to the proper antenna waveguide port at each end of the hop.
6. Consult the path calculations, PDS, for the net path loss calculated between the antennas.
Correct for feedline losses when connected directly to the antenna waveguide ports.
22
Path Align-R™ is a popular test radio. Manufactured by: Spectracom Corp, XL-Microwave,
Pendulum