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— Chapter 3. Mounting the Antennas
RF-7000E Operations Manual
46
8.
Terminate the waveguide with a CPR112G flange connector.
9.
Position the waveguide and secure the bottom section. Carefully bend the elliptical waveguide to
align with the repeater equipment top flange. Be mindful of the bend and twist limits of the
waveguide. If necessary, use rigid twist and bend sections to aid in alignment.
10.
Flexible twist-flex waveguide jumper may be used at either end if needed. These jumpers have
higher loss and shorter life than rigid twist and bend sections.
11.
Trial fit the bottom connector to the repeater equipment top antenna port flange or intended
flange location. Do not permanently install until the feedlines are sweep tested.
12.
Install waveguide grounding kits. Normally the waveguide is grounded at the top and bottom and
at the shelter entrance. Follow grounding practices prescribed by the controlling authority.
13.
Pressure windows are recommended at the repeater equipment top antenna ports.
14.
Install dehydration equipment.
Lightning Protection
Peninsula Engineering Solutions strongly recommends installing protection on the tower, structure
and on all feedlines to the repeater. A direct lightning strike can damage any electronic equipment.
Damage resulting from a lightning strike is not covered under the equipment warranty, whether or not
lightning protection is used. However, using lightning protection can minimize the risk of damaging a
repeater, and of losing equipment operation during thunderstorms.
Elliptical waveguides are protected by installing grounding kits, typically at the top, bottom and at
shelter entrance.
Lightning rods mounted adequately above the highest antenna or power equipment, provide a
diversion path for lightning strikes. Multiple lightning rods may be required.
Towers, shelters and all equipment must be bonded and grounded to minimize any potential
differences that can occur due to a lightning strike.
Follow grounding practices prescribed by the controlling authority.
Sweeping the Antenna Feedlines
Sweep testing of the installed feedlines and antennas is recommended. Sweep testing is the same as
performed at a terminal radio site. Measurement of impedance match and insertion loss over the
operating frequencies insures that the antenna system is installed properly and is ready to perform.
Most microwave operating companies have developed their own performance standards for antenna
systems. Use such standards if available. If company standards are not available, consider the
following:
Sweep frequency range: 7,125 ~ 7,900 MHz or across assigned channel bandwidth.
Impedance Match: 26 dB Return Loss or 1.11:1 VSWR across the channel bandwidth. If
tunable connectors are provisioned, adjust the tuning screws to optimize the match.
Insertion Loss: Per calculated. Typical waveguide loss
15
is 1.9 dB/100 Ft or 6.2 dB/100 m.
Distance to Fault, DTF: Measure Return Loss of the antenna system components and isolate
troubles.
Use DTF function of Anritsu Site Master™ test equipment.
If the impedance match or insertion loss is not met, troubleshoot the feedlines and antennas for the
source of the problem. Use the “Distance to Fault” function to assist in localizing the trouble. Correct
as required before proceeding.
15
EWP77, EP78. Consul
t manufacturer’s specifications for loss at the intended frequencies.