G0RIF/p - an end-fed antenna experiment.
A trip the Barr Beacon this past weekend allowed me to trial and test a simple end-fed antenna comprising a 65ft wire and a 9:1 unbalanced-to-unbalanced (unun) transmission line transformer. According to the manufacturer “the 9:1 unun is a transformer bringing high [impedance] values such as 450 Ohms to a…more manageable 36 to 90 Ohms, thus allowing a much better match to coax feeder”.
9:1 unun |
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There are many who will sniff at this kind of device suggesting “it couldn’t possibly work” or suggesting “you’d be better off with a simple doublet fed with ladder line”. Unfortunately I’m not able to deploy large centre fed antennas with unsightly feed lines. I need to keep my antenna discrete and low profile - this pretty much limits me to simple end fed wires. Furthermore, my policy is always to try this kind of thing and see if or how well it works before passing judgement, fully accepting that it is a compromise solution. |
For the Barr Beacon test the antenna was arranged in an inverted-L configuration, fed at the bottom, with no ground, radial or counterpoise wires (the SRC 9:1 unun used has no ground lug anyway). The 65ft wire was suspended on two fibreglass poles with a 30ft vertical section and a 35ft top section.
In use the antenna tuned on all bands 80m thru 10m (30m was not tested) and received signals were good. Contacts were made on 15m, 17m, 20m and 80m with most activity on 20m where I received good reports across Europe peaking at 59 +5 from Rudy (HB9CCL) in the eastern Alps with whom I had a good long chat. I also got through a minor pile-up to work Hans (JW4EU) on Svalbard.
Whatever it’s limitations the antenna does radiate and on 20m it seems to work just fine. Contest stations worked on a pretty quiet 15m band heard me first call, so it also works ok there. A few stations worked on 17m were a bit more difficult but there were other stations calling. The single 80m contact with GB1SS was difficult copy for him so for now I’ll reserve judgement on both 40m (yet to make a contact) and 80m.
Overall, given the simplicity and convenience of the unun device, and the possibilities if offers for a simple multiband antenna with either a 65ft or a 23ft wire (the latter giving only 40-10m coverage), I’m satisfied that it works well enough to warrant further experimentation. Having tried it with the 65ft wire I’m very interested to see how it performs with the shorter 23ft wire.