ANTENNAS & AERIALS 2 - Amateur Radio by M0MTJ

ANTENNAS ( AERIALS ) 2

THE ANTENNAS AT MY STATION

I use three main antennas:

1/ A trapped Inverted L for 80m and 40m fed by RG213 coaxial cable to the antenna matching unit in the shack. This can be used on all bands from 80 through to 10 meters. The support post is installed at the bottom of the garden with the end of the antenna wire being supported by Dacron rope that is ttached to a pully on a pole at the apex of the roof:

2/ A trapped dipole for 20m and 10m. This is fed by 75 ohm twin feeder to a 1:1 balun then on to the AMU via RG213 coaxial cable. Although it was initially installed horizontally, it is now installed with one leg supported vertically on a 7 meter fibreglass 'Sota' pole with the other leg supported horizontally about 2 meters above the ground. A rather unorthodox arrangement for a balanced dipole, but it seems to work ok, it looks much neater than a horizontally strung dipole and offers a more omnidirectional radiation pattern.

3/ A Watson W-2000 colinear antenna for 6m, 2m and 70cms. This is fixed to the top of a 10m telescopic aluminium mast that I push up whenever it is required.

Inverted L Antenna for 80m and 40m (and all other HF Bands)

The basic layout of the Inverted L Antenna (Practical Wireless)

Photograph showing the wooden support post and termination point of my Inverted L antenna
The post is coloured green with green fence treatment to mast it somewhat. I have also placed
it near the bush to provide further camouflage.

The low loss RG213 coaxial cable runs from the shack at the front of the house up into the loft and
exits into the back garden down the rear wall, through some garden hose to offer some protection
along the flower bed to the bottom of the garden where it is connected to the base of the Inverted L antenna.

The suspended Inverted L 7MHz trap

The Inverted L antenna - lower section now nicely camouflaged. The wooden
support post is some 6 meters long.

Antenna Mast at apex of house

The Dacron ropes supporting the ends of the Inverted L and Dipole antennas are held in place at the top
of the fibreglass support mast by a pulley - one pulley for each support rope. This facilitates rapid
lowering of either antenna for adjustment or replacement. (This photograph shows that only the
support rope for the Inverted L is in use at the moment, the second rope and pulley system could be
used for a Dipole or Doublet antenna.)

It's important to use the correct knot for the job when fixing up wire antennas. I find the Bowline is a very useful for fixing end, egg and dog-bone insulators to the ends of the wire and/or ropes. The Round Turn & Two Hitches, Anchor Bend and Buntline Hitch knots are very good for tying a rope to a pole or a mast. 'Animated Knots' will show you how to do them:
http://www.animatedknots.com

Photo showing pulley fixed to the top of the wooden support post and the aerial support
rope that it holds in place.

Trap

The Spectrum Communications Trap

Trap

View of trap showing that the joints have been thoroughly sealed against the weather with
self amalgamating tape and silicone sealant.

Trap

Just for good measure I sealed the internal side of the machine screw that forms the connection
terminal against the weather with Watson sealant putty.

Dipole or Doublet Antenna for 20m and 10m

This is an antenna trapped dipole for 20m and 10m. I is fed by 75 ohm twin feeder to a 1:1 balun then on to the AMU via RG213 coaxial cable. Although it was initially installed horizontally, it is now installed with one leg supported vertically on a 7 meter fibreglass 'Sota' pole with the other leg supported horizontally about 2 meters above the ground. This is a rather unorthodox arrangement for a balanced dipole, but it seems to work ok and was insired by another radio amateur's idea.

It looks much neater than the horizontally strung dipole and offers a more omnidirectional radiation pattern too.

Dipole Centre with PVC covered wire and 75 ohm twin feeder attached

Removable end support method for wire dipole using a plastic antenna insulator, snap-hook and Dacron rope

Photo showing how the wooden support posts are held in the ground by the steel Met Post. This Met Post and wooden pole now supports the 7 meter high fibreglass Sota Pole (fishing pole)

The 'deformed dipole'.

A Dipole for 20m and 10m.
One leg is vertical, giving a more omnidirectional
pattern and supported by the 7 meter long fibreglass fishing pole, while the other leg runs off horizontally at about 2 meters above the ground.

This antenna is fed by 75 ohm twin feeder.

Vertical Antenna For 50 MHz, 144 MHz and 430 MHz

Watson W-2000 on Telescopic Mast at the lowest position

Watson 2000 on the extended telescopic pole

The Watson W-2000 on to of the extended telescopic pole. Now about 8 or 9 meters high.

KNOTS FOR SECURING WIRE ANTENNAS

When I installed my first wire antenna I was concerned about securing the wire and ropes properly with the correct type of knot.

I have found the Bowline, Round Turn & Two Hitches, Anchor Bend and Buntline Hitch to be some of the most useful.

The Bowline I find most useful for fixing end, egg and dog-bone insulators to the ends of the wire and/or ropes.

The Round Turn & Two Hitches, Anchor Bend and Buntline Hitch knots are very good for tying a rope to a pole or a mast.

More at Animated Knots.com: http://www.animatedknots.com

I know that if I use the correct knot that the these parts of the antenna will be as strong as possible.

Antennas 1 | Antennas 3

If you have got any specific Amateur Radio questions
try visiting a specialist forum on the net :-

Transmission 1

http://www.transmission1.co.uk

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M0MTJ
Subjects covered on this page:
Amateur Radio; Ham Radio; Radio; Transceivers; HF; VHF; UHF; Data Modes; Morse Code; RTTY; PSK31; SSTV; FSTV; Amtor; Sitor
Antennas; Aerials; Cable; Coaxial Cable; Twin Lead; Masts; Poles; Propagation; Computer; PC; USB Computer Interface; Microphone
Loudspeaker; Filters; Noise Reuction; DSP; Digital Signal Processing; Morse Key; SWR ; Inverted L; Inverted V; Dipole; Doublet;