User Manual and Installation of 5/8 Wave Antenna

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

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 at least 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 least 20 meters in height off ground and using 1000 watts of transmitter power, power flux density measurements made at ground level directly under the antenna show less than 1 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.

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

This antenna is intended for use with an FM broadcasting transmitter up to 1000 watts at a permanently pre-defined location with a license or authorisation from the radio spectrum regulator of your country.

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

Using the following items assemble the base section with the tuning loop as shown in the picture below.

• Main radiator tube 1”, mounting section and RF socket
• Two mast fixing clamps
• Tuning loop
• Tuning bar
• Two M6 screws and washers
• M6 screw, aluminium sleeve, two washers and nut

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.

The operating frequency determines the length.

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.

Below is the radiation pattern for our 5/8 antenna showing a cross section of the signal between the antenna and the horizon at 0 and 180 degrees. Looking down from above at the 0 degree point the radiation pattern is perfectly circular.

IMPORTANT!

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.

When writing this manual there was no EU directive regarding the EMC (Electro Magnetic 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;

1.All the cables entering the connectors are tight and properly crimped or soldered

2.All the connectors are screwed in tight and sound.

3.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.

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

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

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

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.

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Every care has been taken in the preparation of this document, errors in content, typographical or otherwise, may have occurred. If you have comments concerning its accuracy, please contact Aareff Systems Limited (UK)