40 mtr vertical hf radio antenna aerial - ultra easy system

of 8 - 40 metre vertical

City dwellers and portable 40metre Vertical.

This is an easy to erect vertical antenna. It uses a lightweight fiberglass fishingpole as a mast and 300 ohm twin feeder as the radiating element.

Great for city dwellers and small spaces - The vertical polarization cuts outmasses of man made electrical noise and QRM, a blessing for city dwellers inthis digitally noisy age.

At my QTH, a city location, local QRM dropped from an awful s8, to anastonishing s0 on 40 metres, with this antenna.. I was amazed by the difference,and grabbed a recording of this dramatic change and decided to document thisantenna. Listen to the difference on youtube at:http://www.youtube.com/watch?v=sVmG5fcEcvI


The antenna has great portability –The vertical extends or collapses in less thana minute.

DO NOT USE THIS ANTENNA WHEN ITS WINDY.

This project started when I bought a 9 metre long glass fibre fishing pole, knownas a 'squid' pole, on ebay. The 'squid pole' is fiberglass, about 42mm diameter atthe base, extending to a slim 7 or 8 mm at the tip. Note: carbon fibre rods are notsuitable for this project.

The pole is made of tapering hollow sections, about 7 sections altogether. Thesesections slide into each other for storage, or slide out, into a hand tightened,compression fit mast, of a full 9 mtrs in length, that can be held in one hand. Theweight is less than a kilogram.

The final section of this ‘mast’ is not hollow, and tapers toa slim 7mm diameter,suitable only to support a light vertical antenna. The squid pole sections collapsedown into the first section, leaving a tube about a metre long when not in use.

The tube is sealed with a large rubber bung when closed. At the base of this firstsection, a screw on cap allows access to the individual sections .

The tube is just the support for the vertical antenna. The antenna itself is madeusing 300 ohm twin feeder ribbon cable.

The ribbon cable antenna attaches to the tip of the last section of the mast, usinga strip of electricians tape. This is the only place where the antenna is attacheduntil the mast is fully raised.


Once the mast is fully raised, a second strip of tape holds the ribbon cable to thebottom of the mast. The whole operation from antenna down to antenna up takesless than a minute !

As the mast sections are raised by hand, and locked into place with a twist of thewrist, the ribbon cable will gently spiral aroud the mast without difficulty as seenin the first picture in this article.

It is only necessary to anchor the bottom of the ribbon cable at the bottom of themast, with a second strip of electricians tape, once the mast is fully raised.

Note. An extra three centimeters or so of antenna height can be gained by fixingthe ribbon cable a few centimeters above the mast tip as in the picture above.Every little helps !


The radiating element.

As seen already, I used lightweight 300 ohm ribbon feeder for the radiatingelement.

The element is shorted at the apex but open circuit at the bottom of the pole. Theelectrical circuit of the antenna looks like this :

A 10 metre length of non slotted ‘TV’ type ribbon cable is used as the radiating element. This is shorted at the top end only. Terminate the bottom end in two4mm crimp or banana sockets as per the diagram above.

By using 4mm socket connectors on the ends of the radiating element,connection via banana plugs allows fast assembly, and easy dismantling of theantenna system. It also allows the antenna to be multibanded .

Leave one end of the radiator unconnected for use on 160 to 40 mts. For usefrom 30 mts to 10 mts the radiator is shorted at the bottom using a banana pluglink as shown in the diagram below :


One end of the ribbon feeder radiator is left unconnected for LF use. (160 80 and40 metres )

It may be preferable to short the radiator ends at the bottom, for use on the30/20/15/17/10 metre bands.

A simple banana plug link makes this an easy task, handled at the base of theantenna and within easy reach, see diagram below:

The 50 ohm coax cable feeder centre conductor is connected to the radiatingelement.

The coax cable braid connects to a 10 metre counterpoise wire laid around theground.

The coax then goes to the radio via an ATU.

Feel free to experiment with counterpoise and grounding systems.


Rasing the mast

Now the fun really begins. We will no longer refer to the squid pole as a fishingpole, and hereon reference the pole as 'The Mast'.

Before operations commence we need to be able to keep the mast upright.

For portable operation I would mount a single U bolt to a vehicle roof rack. Theultra light weight of the antenna system makes adpation easy and safe.

For home use I attached a standard TV mast bracket, and u bolts, from B+Q, tomy wall around 5 feet up:


Again the ultra light weight of this antenna system would allow for a simplerwooden bracket to be fabricated to hold the mast upright, but my woodwork skillsare worse than my antenna making skills ! The base of the mast remains atground level.

There is a golden rule to observe here. The U bolts must be hand tightened only.This gives ample stability for light / portable use. Overtightening the U bolts willcrush the hollow mast sections.

Attach the mast bracket at a convenient point to work , around eye level.

When ready to use the antenna, remove the rubber bung and slide the finalsection of the mast out, and through the U bolts. Attach the antenna ribbon cableto the final section of mast with a twist of electricians tape:

Now raise the mast section by section.

Start by raising the final section until the next section appears, and hand tightenthe join with a simple twist of the wrist. Repeat this for all sections, until the mastis fully raised.


This is easily achieved due to the light weight of the mast and the taperingcompression fit of each section, and it is raised in under a minute. Dropping themast sections back down is just as simple.

Once the mast is erected, a final piece of tape may be placed at the bottom ofthe antenna, to hold it in place.

The system is now ready for use. The results when compared to my horizontallongwire were fascinating. The reduction in qrm was a godsend. It allows theweaker signals to be heard once more, for the first time in years.

73 de g0ierjuly 2010

40 mtr vertical hf radio antenna aerial - ultra easy system

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