Friday, June 23, 2017

Playing with 6m Es - compact beam versus vertical

Some time ago I built a compact beam for 6/4/2m aimed at /P operations. It is a design by DK7ZB featuring 3 elements on 2m, 2 elements on 4m and 2 elements on 6m. I tested it when I finished building it and SWR was good on all bands.

I followed the design of DK7ZB (link) with a few changes to make this a /P antenna:
  • I use wing nuts on the 4m elements and the 6m reflector to be able to remove them easily for transport
  • I split the 6m driven dipole in a short center piece connected to the boom and removable parts on both ends of the dipole
  • I added spacers for the dipoles to keep them at the right distance from each other (refer to picture below)
Spacer for the dipole elements

Apart from a short appearance in LX (2 QSOs), I had not used the beam on the air. For 6m I use an end fed half wave vertically - both when I am /P as well as at home.
It is amazing how effective a vertical wire is in Es conditions. I have worked stations all over Europe with that antenna using 100w. I was curious how the beam would perform in comparison.

We are in the Es season at the moment and there was a 6m contest on last weekend. So I decided to go out /P and test the beam properly against the end fed wire. I used one of my Spiderbeam poles with the end fed wire in the top (feedpoint about 12m high) and the beam a bit lower at about 8m high.


I used an antenna switch to be able to quickly switch between the two antennas. You need quick switching as the signals themselves vary constantly under Es conditions. The difference was significant most of the time. Of course the heading of the beam is a factor that influences the difference. With the beam heading the right way, the signal strength on rx differed multiple s-points. On the low end this meant there were stations I could only copy on the beam. I recorded a view video's while switching between the antennas. One of them is on YouTube:


With PG8M - who lives just under 30km from where I was /P - I tested the characteristics of the beam via ground wave. We found a difference of 2 s-points front to back and 5 s-points front to side.

All in all this shows me that this beam is definitely an interesting antenna to use in the field for 6m. It is light, easy to set up and relatively easy to transport. As the 6m reflector is rather long for easy transportation I am thinking of splitting the reflector in two or three parts.

While I was testing this setup I logged 25 stations, collecting 10 new grid squares on the go.

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