Purpose of this article: This article describes what to consider when choosing HF antennas

 

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What are your antenna options and what will suit your situation?

You need to consider things such as:

  • What bands interest you?
  • Are you keen to chase DX on 28, 21 and/or 7.0MHz?
  • Do you prefer a rag-chew on 3.5 and 7.0MHz?
  • Do you want to experiment constructing antennas?
  • What modes will you use?
  • How much space do you have to install antennas?

 

If you’re unsure of your needs,  you should have a chat with fellow amateurs.  Construction is a hallmark of this hobby.  Try building simple antennas before you look at commercial antennas.  It will be far cheaper, will operate just as well, and you’ll get the satisfaction of having built your own antenna.

 

Very few amateurs have the perfect location for of HF antennas, but by using a little ingenuity it is possible to operate from almost any residence. Your antenna may not look straight like the perfect pictures in books, magazines and guides; but it will work.

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Suggestions

 

The Dipole Antenna

The dipole antenna and derivatives have been the mainstay of radio communications, both amateur and commercial..

 

Pros:

  • Cheap and easy to construct
  • Easy to tune and will work well

 

Cons:

  • On balance, not really many.  This  is a good beginner antenna.
  • Depending on the frequency desired, the length may be an issue, but there are solutions.
  • Usually works on the frequency it was made for, however there are types of dipoles which are multi-band

 

 

Things to think about:

  • Get your dipole as high as possible and in the clear
  • Be aware of potential dangers.  Keep all antenna wires and guys well clear of power lines, phones lines and other services.

     
  • The dipole does not have to be straight.  You can  bend   it, for example to fit into your block. Another alternative is you could make some loading coils.  Coils add inductance, make the antenna shorter, but keep the antenna resonant. Whilst not an easy project for beginners, it would be a great way to experiment, learn and prepare to upgrade your licence (if that is what you want to do).
  • A 40M dipole is 20m long and it should fit onto most residential housing blocks. It should also work well on 3rd harmonic, the 15m band.
  • A balun is desirable, but if you are in a hurry to get on air, can be included later.

 

Some derivatives of the simple dipole are:

 

Inverted “V”

 

A dipole antenna that is highest at its feedpoint and takes up less space. Although an inverted-V has its greatest degree of radiation at right angles to the axis of the antenna, its radiation pattern is more omnidirectional than that of a horizontal dipole.

 

 

 

 

 

 

Off centre Dipole (Windom)

 

A mulitiband antenna similar to a dipole, except it is fed off centre. An excellent article on constructing one is available from the Radio and Electronics School.

Ron Bertrand VK2DQ - Off Center Fed Dipole - Build this off centre fed dipole which can be used on 80, 40, 20 and 10m with out an antenna tuning unit. ocfdipole.pdf

Multi-band Dipole

 

By adding additional elements from the feed-point cut for other bands the antenna can be more useful for multiband use.

Trap Dipole


 By using parallel tuned circuits (Traps) that appear as an almost open circuit at their designed frequency, a dipole can be made to work on two or more bands. Making your own traps is a challenge for the new amateurs, but the skills and knowledge gained invaluable of other projects.

Broadband Dipole

 

A non-resonant antenna capable of a low VSWR over a number of bands.

Cobweb Antenna

 

A multiband dipole antenna for 20M to 10M with the elements folded to take up less space and is supported using simple mast hardware. The antenna is non directional and is almost as efficient as a regular dipole. Real world Efficiencies may be better due to height and clearances and may suit your situation.

 

Top View

Other Wire Antennas

 

Hex Beam

 

By adding extra Reflector elements into the design, you can make a wire antenna that is directional and has gain known as a Hex Beam. 

 

There are kits available or build your own.
 

The Hexbeam is directional and has gain over a Dipole. Needs a Antenna Rotator to point on the desired direction.

End Fed Antenna

Although the End Fed Antenna appears to be a simple antenna matching and earthing can present a challenge. 

 

 

 

Pros are:

 

  • low cost,
  • Easy to install initially
  • Multiband operation possible
  • Low Cost

 

Cons are:

  • Susceptible to receiving interference, 
  • Can in some situations case interference
  • High levels of radiation close to the transmitter can give rise to RF feedback creating odd effects. May need a line isolator (choke balun) to prevent RF getting into equipment.
  • Requires good earth connection. 
  • Usually require an Antenna Matching Unit and/or an Un Un matching transformer

 

Vertical Antennas

May be made from wire, aluminium tube fibreglass etc. 

 

Pros are:

  • A very good DX antenna with a low angle of radiation
  • Much easier to fit into a small housing block
  • Cheap and easy to construct.
  • Easy to tune and will work well
  • A 40m Band vertical should also work well on 3rd harmonic, the 15m band.
  • Being relatively short you should be able to engineer a support, if the antenna is not free-standing
  • Easy option for VHF/UHF FM Bands.

Cons are:

  • Beware of those who depend on the coax braid as a radial (a Vertical Long Wire)
  • Verticals are more prone to picking up local noise.
  • Radials are critical to effective operation. May require many radials (HF)

An example of a Vertical Antenna

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Useful links

 

For reviews of commercial antennas try this link

 

https://www.eham.net/reviews/index

 Some Suppliers of antenna components and kits;


 Rippletech http://rippletech.com.au/index.html
 Tet Emtron https://www.tetemtron.com.au/ 

NBS Antennas and Masts https://www.nbsantennas.com.au/

 

FURTHER READING ON WIRE ANTENNAS

Radio and Electronics School – Ron Bertrand VK2DQ -  Off Center Fed Dipole - Build this off centre fed dipole which can be used on 80, 40, 20 and 10m without an antenna tuning unit. ocfdipole.pdf

The G5RV multiband antenna developed to fit a UK house block is a popular dipole variation  http://www.astrosurf.com/luxorion/qsl-g5rv.htm 

“A Bundle of Wet String” by Edwan R. McLeod VK4ERM is a great reference
View/Download Here

A homemade VHF/UHF antenna you can make yourself called the “Flower Pot”. https://vk2zoi.com/ 

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