USER MANUAL – 87.5 TO 108.0 MHz BAND II 4.8dBi 5/8 WAVE ANTENNA

1. INTRODUCTION

WARNING-TRIANGLE

Please read this manual carefully. To avoid harmful interference to other users of the electromagnetic spectrum, do not power up the antenna until it is properly installed.

1.1. General Information

The antenna is the most important part of the transmission system and must be correctly installed before any transmission equipment is connected

1.2. Unpacking and Checking

The package should contain the following:

  • A. Main radiator tube 1”, mounting section and RF socket
  • B. Main radiator tube 7/8”
  • C. Main radiator tube ¾”
  • D. Main radiator tube ½”
  • E. 4 x Ground plane tubes ½”
  • F. 8 x M4 screws, washers and nuts (only 4 shown in picture)
  • G. 2 x Mast fixing clamps (not shown in picture)
  • H. 3 x Tube clips
  • I. Tuning loop
  • J. Tuning bar
  • K. M6 screw and 2 washer
  • L. M6 screw, 1 aluminium sleeve, 2 washers and 1 nut

5-8-fm-transmitter-antenna-aareff-parts-list

Verify that the parts are there and are in good condition and have not been damaged during transport. In case of loss or damage please contact at info@aareff.com

1.3. Warranty

This product can only be installed and serviced by suitably qualified personnel. If difficulties arise during the installation please contact us by email at info@aareff.com

1.4. User Safety Responsibility

You are responsible for selecting the correct antenna for your application, installing it properly and ensuring the system maintenance.

1.5. Installation Near To Power Lines

This product can only be installed and serviced by suitably qualified personnel. If difficulties arise during the installation please contact us by email at info@aareff.com

WARNING-TRIANGLE

Following is a list of precautions to follow when installing the antenna if placement of antenna and cables is anywhere near power lines


  • Erect antenna on pole, mast or tower as far away as possible from the power lines
  • Avoid crossing antenna cables under electrical power lines
  • Do not attach antennas to towers, poles or similar structures carrying electrical power lines
  • If you are not experienced in installation of antennas, have experienced persons assist you
  • During installation, tie off antenna with a rope so if it falls it can be diverted away from the power lines.
  • Avoid fastening antennas, especially self-supporting types, to old chimneys or to any chimney not designed to take such stress. Forces created by a strong wind may be sufficient to topple both chimney and antenna.
  • Make sure antennas have been properly grounded and provided with other necessary lightning protection

1.6. Radio Frequency Radiation to Personnel

WARNING-TRIANGLE

Under no circumstances should the antenna be mounted and used at ground level or within a few meters of personnel.


Ideally this antenna should be mounted 20 meters high and clear of any surrounding objects to get maximum range and more importantly to reduce risk of radio frequency radiation to personnel. When mounted at 20 meters in height off ground and using 800 watts of transmitter power, power flux density measurements made at ground level directly under the antenna show less than 2 W/m2. Several European countries use a value for the power flux density of 10 W/m2 as a basis for considering whether or not an area is safe. The issue of radio frequency radiation limits is a contentious one and work in this field is continuing worldwide.

1.7. Electromagnetic Compatibility

When writing this manual there was no EU directive regarding the EMC compatibility of Band II VHF broadcast antennas, however in our view there are some potential EMC compatibility issues that need to be addressed when installing this antenna system. On completion of the antenna installation check;

  • All the cables entering the connectors are tight and properly crimped or soldered
  • All the connectors are screwed in tight and sound.
  • PVC insulation tape and/or self amalgamating tape are wrapped around all the connectors to stop water entering the connector and the inside of the body of the cable.

If any cables are loose or there are bad connections this can cause some non-linear resistance, diode action or some small arcing. When this happens it creates EMC disturbance (arcing and crackling sound) across a wide frequency spectrum.

1.8. Intended Use

This antenna is intended for use with an FM broadcasting transmitter up to 800 watts at a permanently pre-defined location with a license or authorisation from the radio spectrum regulator of your country.

2. SPECIFICATION AND DESIGN

Gain 4.8 dBi at tuned frequency (see radiation plot below)
Frequency 87.5-108.0 MHz
Bandwidth +/-2 MHz for SWR of 1.5
SWR 1.1 Max at tuned frequency
Max Power 800 Watts
Construction Aluminium and Teflon
Connector UHF/SO-239 or N-Type
Input Z 50 ohm unbalanced
Polarisation Vertical
Weight 2 Kg

aareff-5-8-E-plane-radiation-plot

The design uses a main radiator of 5/8 of a wavelength. This is the maximum length that can 8be used for maximum radiation to the horizon. Any longer than 5/8 and the radiation starts to tilt upwards to the sky. The feedpoint to the actual 5/8 tube is not 50 ohms or close to 50 ohms, it’s high impedance close to a 1000 ohms. A transformer made from the Tuning loop, aluminium sleeve and Tuning bar match the 50 ohms to the high impedance.

3. TOOLS AND OTHER ITEMS NEEDED

  • PVC insulation tape and/or Self Amalgamating Tape
  • Metric Tape Measure at least 3m
  • 13mm Spanner or Socket and Wrench
  • 10mm Socket and Wrench
  • Flat Screwdriver
  • Mounting mast or pole with a diameter of 40mm or less
  • Antenna 50 ohm feeder cable, normally this is LMR400

4. ASSEMBLING THE ANTENNA

4.1. Assembling the Base Section

Using the following items to assemble the base section with the tuning loop as shown in the View of Base Assembly.

  • 1 Main radiator tube 1”, mounting section and RF socket
  • 2 Mast fixing clamps
  • 1 Tuning loop
  • 1 Tuning bar
  • 2 M6 screw and 2 washer
  • 1 M6 screw, 1 aluminium sleeve, 2 washers and 1nut

The tuning loop, bar and aluminium sleeve form an half turn inductor. The operating frequency determines the position of the aluminium sleeve. Put the aluminium sleeve in one of the six positions shown in View of Base Assembly picture for the frequency that you want. This sleeve will be carrying a huge RF current, make sure it is tight and firm. The tuning loop and bar should also be screwed tight to the Teflon section with the two M6 screws and washers and also to the back plate using the mast fixing clamps. This is shown in the pictures.

Fit the four ground plane tubes to the top plate of the base section and secure them tight with the four M4 screws and nuts.

4.2 View of Base Assembly

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4.3 Adjusting the Length

The operating frequency determines the length.

5-8-fm-transmitter-antenna-aareff

Screenshot 2016-04-20 11.36.09

Pick the frequency (MHz) from the table that is the closest to frequency you need to use. For example if you needed 91.3 MHz, then you would pick 91.5 MHz, this is the closest. Then adjust the length of the antenna to the Metres shown for that frequency. Use a metric tape measure to measure the length from the (IMPORTANT) top plate of the base section to the end of the top tube.

Slide the tubes inside each other until the correct length is reached. At the correct length tighten the circular screw clips to secure the tubes in place. Make sure the clips are tight and the tubes don’t move. DOUBLE check the length again from the top plate of the base section to the end of the top tube. If this length is not correct, the antenna will not radiated correctly.

circular screw clips to secure the tubes in place. Make sure the clips are tight and the tubes don’t move. DOUBLE check the length again from the top plate of the base section to the end of the top tube. If this length is not correct, the antenna will not radiated correctly.

5. POWERING THE ANTENNA

WARNING-TRIANGLE

An incorrect antenna installation can cause RF burns and levels of RF exposure above the recommended limits for personnel


Under NO CIRCUMSTANCES should the antenna be mounted and used at ground level or within a few meters of personnel

Ensure that all antenna connections to the transmitter or power amplifier are sound, this is important as poor connections and soldered joints can cause RF burns to personnel, severe noise to the transmission and excessive RF bandwidth.

If the antenna is installed and tuned correctly and you have an Antenna Analyzer, Network Analyzer or other SWR / Return Loss measuring equipment, you should expect to see results similar to our tests shown below.

5-8-antenna-network-analyzer-swr-return-loss

6. MAINTENANCE

Because antennas are passive devices maintenance requirements are low, however don’t accept low as being none existent, some periodic inspections are required.

Antenna Inspection List;

  • Check antenna is still rigid and tight on tower, mast or pole and vertical tubes are still exactly vertical as opposed to twisted and slanted.
  • The PVC tape insulation or self amalgamating tape still covers all the connectors properly and the connectors remain tight.
  • The antenna feeder cable (normally LMR400) continues to be held rigid to the boom, tower, mast or pole.

Always following a heavy storm or extreme weather condition an inspection should be done and as shown in the table below.

ENVIRONMENTS

WEEK Heavy Duty Tower Light Duty Tower Building Roof
13
26
39
52

7. LEGAL ADVICE

We sell this equipment to professionals and organizations in good faith it will be used correctly and legally. Most countries in the world require licensing for this antenna to be used with a transmitter. It is the customer’s responsibility to check relevant laws, directives, regulations and licensing requirements before putting this product into service with an antenna system. You, the customer or user agree to defend, indemnify and hold harmless Aareff Systems Limited, its employees and agents, from and against any claims, actions or demands, including without limitation legal and accounting fees, alleging or resulting from improper or unlawful use of this equipment

Care has been taken in preparing this document, errors in the content, typographical or otherwise, may have occurred. If you have comments about its accuracy, please contact Aareff with specific details at info@aareff.com Aareff Systems Limited is UK registered company 7140572. © 2016 Aareff Systems Limited. ALL RIGHTS RESERVED. Aareff is a registered trademark of Aareff Systems Limit5ed. The entire contents of this document, including but not limited images, logos, text, illustrations are protected by copyrights, trademarks and other intellectual property rights owned and controlled by Aareff Systems Limited or other parties that have licensed their material to Aareff Systems Limited. This document in part or in whole may not be copied, reproduced, republished, uploaded, posted or distributed in any form, including email, FTP or any other electronic means