Trapped Dipole for 60 / 40m

John Elvy - ZL2BH

This article is aimed at Hams living in small town sized sections not enjoying the opportunity to install a dedicated 60m antenna.

Many Hams simply tune their 80m Dipole to 60m but this is far from efficient due to 60m having no direct harmonic relationship to other common HF Bands. Having been a 60m DX operator I know how important it is to get an efficient antenna for 60m working within our low power limitations for this band (15watts EIRP).

In my own case I looked at my various antenna arrays which are Fan Dipoles and wondered how I could add 60m to my system. The solution was actually very simple, I modified my existing 20/40 Fan dipole antenna to accommodate 60m. I added a 40m trap and a length of wire to each end of the dipole.

The addition of traps made absolutely no difference to the operation of the 20/40m antennas. The completed antenna allows me to work 20/40/60 without an Antenna tuner in the portions of each band I wish to work.

Steps

Build two 40m Coaxial Antenna traps (see below for more detail) and insert these in place of your 40m end Insulators. Do not connect the traps up electrically at this stage.
Raise your 40m antenna to the required height and if necessary alter the length of your standard 40m dipole to check and adjust the tuning in the section of 40m you wish to work.
Once you are happy with stage 2 then electrically connect one end of each trap to your dipole and add approx 2m of wire to the other trap end then add your end insulator. (This will be longer than the end result but will allow tuning)
Raise the antenna and adjust the length of added wire to obtain the lowest swr on 5.360MHz. Note when tuning the antenna the adjustments to each end of your dipole must be identical.

Trap Construction

I used standard 40mm PVC Plumbing pipe, OD is approx. 43mm.
I used RG58CU Coax
The completed trap worked out at 10.25 turns for resonance at 7.090Mhz I suggest you may wish to start with 10.5 turns and check the resonance is easy to drill an extra hole in the pvc pipe if need be. Some precise tuning can be done by compressing or spreading coax turns on the former.
For help getting your traps to resonance refer to Break In Sept/Oct 2024 page 8.

If the idea of using coaxial traps is not appealing then make yourself a couple of toroidal traps HV Capacitors (1KV)

ZL2BH Oct 2025