Barrett 2018 Specification sheet

No part of this manual may be copied, transcribed, translated or reproduced in any manner or form whatsoever, for
commercial purposes, without obtaining prior written permission from Barrett Communications Pty. Ltd. However,
limited copying is permitted for private use providing authorship is acknowledged.
The 2018 Mobile magnetic loop HF antenna design is protected by Australian patent 2001100423. Unlicensed
replication of the design is expressly forbidden.
BCM201800/6
© Barrett Communications
Head Office:
Barrett Communications Pty Ltd
47 Discovery Drive, Bibra Lake, WA 6163 Australia
Tel: [phone] Fax: [phone]
Email: [email protected]
www.barrettcommunications.com.au

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Introduction...........................................................................................................................................4
Features.........................................................................................................................................4
General ..........................................................................................................................................5
About this Guide...........................................................................................................................6
Glossary of Terms........................................................................................................................6
Warnings and Advice...........................................................................................................................7
High Radio Frequency Voltages .................................................................................................7
Power Supply Cables...................................................................................................................7
Radio Frequency Field Exposure................................................................................................7
Explosion Hazard .........................................................................................................................7
Storage of Other Goods...............................................................................................................8
Frequency Hopping Use ..............................................................................................................8
Operation in Rough Terrain.........................................................................................................8
Overview................................................................................................................................................9
Installation...........................................................................................................................................11
Fitting on Vehicles With Gutters.......................................................................................................11
Setting Up the Roof Rack ..........................................................................................................12
Preparing the Vehicle.................................................................................................................15
Fitting on Vehicles Without Gutters .................................................................................................17
Setting Up the Roof Rack ..........................................................................................................17
Preparing the Vehicle.................................................................................................................18
Maintenance........................................................................................................................................21
Removal of Rack.................................................................................................................................21
Retrofitting the 2018 Barrett Mobile Magnetic Loop Antenna........................................................21
Cabling.................................................................................................................................................22
Operation.............................................................................................................................................23
To Deploy the Antenna ..............................................................................................................23
To Stow the Antenna..................................................................................................................24
Barrett Transceiver to 2018 Barrett Mobile Magnetic Loop Antenna Setup .................................25
Supported Barrett Transceivers................................................................................................25
Testing and Troubleshooting............................................................................................................25
Troubleshooting .........................................................................................................................26
Testing.........................................................................................................................................27
External Connectors ..........................................................................................................................28
ATU 6 Pin Connector Functions ...............................................................................................28
Internal Jumper Configurations................................................................................................28

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J5 Jumper Settings ....................................................................................................................29
J6 Jumper Settings (DC Supply on RF Cable).........................................................................29
J7 Jumper Settings ....................................................................................................................29
Parts List .............................................................................................................................................30
Technical Specifications....................................................................................................................31

Introduction
Features
•Highly efficient antenna, radiating 10 dB to 14 dB more than whip antennas.
•Simpler installation – no need to weld on a mounting plate for a whip, and no separate tuner
to install. Installation is therefore quicker and cheaper, and the system can be moved
simply between vehicles.
•Free roof rack with every package. The antenna can be used as a conventional roof rack
for storing luggage.
•Eliminates Skip Zones. A HF system that can be used in ranges from 0-1,000 km and more.
•Increased immunity to ignition and power line noise.
•Broadband low-noise scan amplifier.
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General
The 2018 Mobile magnetic loop HF antenna is a technological breakthrough in vehicle-based HF radio
communications.
The 2018 Mobile magnetic loop HF antenna is available in a range of packages for fixed or removable
installations and can be used with Barrett 2000 Series transceivers. The removable package can be
installed without any drilling of holes in the vehicle.
The 2018 Mobile magnetic loop HF antenna is without doubt the best type of antenna for vehicular
NVIS (Near Vertical Incidence Skywave) operations. Skip zones are eliminated and coverage (with
the correct selection of frequency) is from 0 to 1000 km or more. Within this range it is significantly
more efficient than any whip-type vehicle antenna; producing considerably more transmit and receive
strength. The actual gain over whip antenna systems varies between +10 dB and +14 dB. The
benefit to the user is that it radiates significantly more power, and magnifies received signal strength,
giving overall performance much higher than can be achieved from any vehicle whip antenna system.
The 2018 Mobile magnetic loop HF antenna tuner unit is a highly efficient, continuously variable
capacitor unit which is driven by a stepper motor to give the best VSWR reading.
When tuned the 2018 antenna has a very narrow bandwidth for transmission. This characteristic is
also beneficial for reception since interfering signals separated from the tuned frequency by just a few
percent are greatly attenuated, protecting the front end of the receiver from intermodulation and
blocking effects.
During scanning the tuning capacitor is bypassed and a low-noise high-linearity amplifier is inserted in
the signal path. This allows the loop to retain its desirable NVIS characteristics whilst offering
broadband receive capability.

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About this Guide
The main purpose of this guide is to provide you with all the information you require to ensure optimum
performance from your 2018 Mobile magnetic loop HF antenna.
The Guide explains in detail how to operate the 2018 antenna once it has been installed by an
authorised Barrett Communications representative.
The Guide also covers the basic principles of installation. However, we recommend that the
installation of your 2018 be carried out by a qualified Barrett Communications representative.
Glossary of Terms
ATU Antenna Tuning Unit
HF High Frequency
kHz Kilohertz (measure of frequency)
km Kilometre
MHz Megahertz (measure of frequency)
PEP Peak envelope power
PTT Press To Talk
Selcall Selective Call
Telcall Selective Call with Telephone Call facility
VSWR Voltage standing wave ratio
W Watt

Warnings and Advice
High Radio Frequency Voltages
When transmitting, radio-frequency voltages up to 1500 V RMS are present on the
radiating arm and associated cables of the 2018 Barrett Mobile Magnetic Loop
Antenna. These voltages are sufficient to cause electrocution or severe radio
frequency burns. Personnel must not under any circumstances come into contact
with the radiating arm of the antenna or the associated cables when the unit is in
operation.
Power Supply Cables
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High Frequency transceivers require adequate supply current. It is essential that the
supplied cables are utilised to reduce the likelihood of system malfunction. Please
use the specified cables.
Radio Frequency Field Exposure
The 2018 Barrett Mobile Magnetic Loop Antenna produces high localized radio
frequency fields. As long as personnel are beneath the level of the roof rack,
exposure to fields will be well below safe operating levels.
Explosion Hazard
Highly flammable materials (e.g. gasoline, petrol, butane, propane, etc) should
not be stored on the roof rack when the equipment is in operation. The induced
RF field during transmission may cause spark discharges between adjacent metal
objects which could cause the material to ignite.

Storage of Other Goods
Goods of normal flammability (for example, tyres, suitcases, tents, etc) may be
safely stored on the roof rack, however metallic items like tent poles should be
secured away from the radiating arm to avoid degrading the ATU's performance.
They should be secured so that no movement occurs during transport.
Important:- Do not use the antenna arm to tie any object down. Keep goods
at least 0.3 m away from antenna arm and feed cables.
Frequency Hopping Use
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Due to the narrow operating bandwidth of the loop antennae, they are not ideally
suited for frequency hopping use. However, at higher frequencies (approximately 7
MHz) and when there is adequate signal to noise ratio, adequate results may be
obtained.
Operation in Rough Terrain
Following operation in rough terrain, the mounting leg fixings should be checked and
re-secured as necessary.

Overview
The roof rack has been designed by Barrett Communications Pty. Ltd. as an integral part of the
antenna system. The ground plane is a heavy-duty aluminium mesh floor, welded to an enclosing
frame which maximises current in the radiating loop. The 2018 Barrett Mobile Magnetic Loop Antenna
shields and isolates vehicle ignition noise and interference from adjacent power lines providing greater
communication clarity.
The 2018 Barrett Mobile Magnetic Loop Antenna can be fitted to almost any surface. The roof rack
comes in a range of mounting bracket options. Solutions are available that will allow clamping to the
roofs of 4WD’s, sedans, buses, trucks and prime movers. It is designed to minimise head wind noise
with an angled deflector mounted on the front of the unit.
A simplified diagram of the parts that make up the 2018 Mobile magnetic loop HF antenna is shown
below.
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The antenna consists of a looped aluminium arm hinged to an aluminium roof rack which forms an
effective ground plane.
RF and DC power is supplied to the 2018 Barrett Mobile Magnetic Loop Antenna system from the
transceiver. The vehicle battery supplies the transceiver with its DC power.
The RF Feed box receives its RF input from the transceiver via the ATU box and an RF coaxial cable
(supplied). The output is connected to the antenna.
The scan amplifier and the associated receive-transmit switching are incorporated within the ATU.
A simplified block diagram of the circuit is shown below:
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Stepper
motor
Microprocessor
control
Scan
amplifier
Antenna
Radiation resistance +
ohmic losses
Variable
capacitor
RF
feedbox
Voltage
sample
SWR
detector
Transceiver
To
microprocessor
Antenna tuner
Transmit/receive
switching
The antenna is effectively a parallel tuned resonant circuit, with the feed-point forming an auto-
transformer in the inductive arm of the tank. Resonance is achieved through a stepper driven variable
capacitor. An on-board microprocessor monitors loop current, with final tune based on system VSWR.