Regular readers may recall I tried to build a convoluted loop for 15m some time ago, which initially was a disappointment but on re-examination, worked just fine.
So I had the support structure made of the old 15m beam PVC lying around (as you can see from the algae in the photo!) I decided there were ideal to run a full wave loop for the 6m band, approximating a circle and so having a greater capture area than any other shape. I threw together a reflector to make a 2-element beam yielding perhaps as much as 7dBi gain. The spreader elements are hooked up to the boom using cable ties, as it's a purely seasonal antenna, for me at least, so can be pulled apart very easily later. I melted holes using 3/4" copper tube in a blowtorch, and then glued PVC support cross arms to which the main elements are attached.
|Runs beautifully at 1:1.2 SWR. All-PVC construction, including the 36"-long boom.|
I referred to this fine site, and by keeping to the measurements for the two element version (plus the 'extra ' bits for trimming) indicated there, I found I had an SWR of 1:1.2 without any cutting or adding at all. How often does that happen? Connection is via a quarter-wave stub (allow for the velocity factor, assumed to be 0.66 here) and then to normal 50-ohm coax; again, the stub measurement is correct on the site link above. A ferrite or air-wound balun is needed (air wound is fine in most cases).
We'll see how it fares over the coming days. I find loops work really well. The down side is that it's pretty big, relatively heavy compared to an aluminium tube yagi, and eye-catching. A flat yagi might be more attractive. For sure, if it gets windy here, it will have to come down!