User Manual and Installation of Folded Dipole Antenna


FDA Aareff Folded Dipole FM Transmitter Antenna

IMPORTANT!

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 400 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.

INTENDED USE

This antenna is intended for FM broadcasting at a permanently pre-defined location with a license or authorisation from the radio spectrum regulator of your country.

NEAR POWER LINES

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

PACKING CHECKLIST

FDA Aareff Folded Dipole Antenna Packing Layout FD
QtyItem
1 A. Boom, RF connector, 1/4 wave match and balun, marked  BLUE  and  GREEN 
1 B.  BLUE  Top fold section.
1 C.  GREEN  Bottom fold section
2 D. M6 x 40 screw, M6 plain washer and M6 spring washer
1 E. 22mm diameter insulator
2 F. Joining clamps
4 G. M6 x 40 screw, two M6 plain washers, M6 spring washer and M6 nut
2 H. Mast fixing clamps with four M6 x 50mm screws, eight washers, four spring washers and four nuts with each clamp (shown in more detail below)

H Mast Clamps

FDA

ASSEMBLING THE FOLDED DIPOLE

Tools You Will Need
PVC insulation tape or Self Amalgamating Tape.
Metric Tape Measure.
10mm Spanner.
13mm Spanner.

1. Assemble The Complete Folded Section
Take the B top fold section marked in  BLUE  and join it to the C bottom fold section marked in  GREEN  using the F joining clamps and G four M6 screws and washers. Make sure the plain washers and spring washers are applied exactly as it shows in the image below.

FDA Aareff Folded Dipole Joining Bracket 1

Fit and tighten the four M6 nuts to the M6 screws using a 10mm spanner as shown here.

FDA Aareff Folded Dipole Joining Bracket 2

When this is complete the folded section should look like this.

FDA Aareff Folded Dipole Joining Bracket 2

2. Assemble The Insulator
Pass the E 22mm diameter insulator through the tube marked  GREEN  or  BLUE  on the folded section. Push it all the way through until it appears in the middle of the tubes as shown here.

FDA Aareff Folded Dipole Insulator Prep.

3. Join The Boom And The Folded Section
Take the folded section and join it to the A boom section using the D two M6 screws, plain washers and spring washers. It's important that as shown in the image below 1.) The  GREEN  and  BLUE  parts go together and 2.) The M6 screws and washers are placed exactly as shown, spring washer next to the screw head and the plain washer next to the tube.

FDA Aareff Folded Dipole Joining Folded Section To Boom.

Using the 10mm spanner, tighten the M6 screws between the folded section and the boom. There should be no slack in the whole assembly, it should be tight, firm and rigid.

FDA Aareff Folded Dipole Tightning Folded Section To Boom.

The folded dipole is now ready to mount to the tower or mast.

TOWER MAST INSTALLATION

1. Using the parts in H assemble the mast clamp as shown in the image below. Fix the boom of the folded dipole to the tower / mast using the mast clamp. For the lowest VSWR / reflected power make sure the distance of 100cm is maintained between the tower / mast and the folded section as shown in the image below.


FDA Aareff Folded Dipole Tower Mast Installation

2. Connect the main feeder cable from the transmitter to the RF connector on the folded dipole antenna.

3. Wrap PVC or better Self Amalgamating tape tightly around and over the plug to waterproof them.

4. Securely fix the coaxial cable using PVC tape or large cable ties to the tower / mast. Make sure the cable is not going to flap around in the wind.

5. Make sure that all fixings are tight and are not going to work loose over time with wind.

VSWR PERFORMANCE


FDA Aareff Folded Dipole VSWR Perfromance

SPECIFICATION AND DESIGN

Gain 2.1 dBi
Freq Range 87.5 to 108 MHz
Bandwidth 21 MHz
VSWR 1.2 max
Max Power N type Female 800W
7-16 DIN 3kW
Construction Aluminium, Fibre Glass, Resin and Stainless Steel
Input Z 50 ohm unbalanced
Polarization Vertical
Weight 2 Kg

3D VERTICAL PATTERN

CIRCULAR ANTENNA 3D COMBINED RADIATION PATTERN

H PLANE

CIRCULAR ANTENNA H PLANE VERTICAL AND HORIZONTAL

E PLANE

CIRCULAR ANTENNA E PLANE VERTICAL AND HORIZONTAL

EM COMPATIBILITY

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.

MAINTENANCE

Because antennas are passive devices maintenance requirements are low, however donít 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.

WEEKSBuilding RoofLight Duty TowerHeavy Duty Tower
13
26
39
52

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 customerís 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.

© 2021 AAREFF SYSTEMS

ALL RIGHTS RESERVED. Aareff is a trademark of Aareff Transmission. All contents of this document including, but not limited to the images, logos, text, illustrations are protected by copyrights, trademarks and other intellectual property rights which are owned and controlled by Aareff Transmission Systems or by other parties that have licensed their material to Aareff Transmission Systems. This document in part or whole may not be copied, reproduced, republished, uploaded, posted or distributed in any way, including by e-mail, ftp or any other electronic means

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 us.

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