There was some activity on 6m this morning, some sort of contest, and so I did a quick web search and came across this simple design for a 6m Delta Loop antenna by DL5DBM, Anwar Von Sroka.
My construction used PVC pipe and it sits on a balcony on the first floor.
Following the instructions in DL5DBM's design yielded an antenna that resonated beautifully at 49Mhz, low SWR and impedance of 50 ohms. The 99cm of 75 ohm coax does a great job of matching. I assume this is a quarter wave transformer but I'm not clear on how the length is derived.
This is one of the most satisfying simple antennas I've constructed - in terms of resonating nicely at about the right spot.
I've cut down the length of the main loop to bring it up to the 6m band but the resonance isn't as pronounced, not sure if the matching coax needs to be tweaked as well.
I heard VK2AWX portable on 50.152 USB and the VK2WI Sunday broadcast from Dural on 52.525 FM is a solid S3 here I was acknowledged in the very brief call-back (so I'm getting out) but didn't get a signal report. Dural is about 35km away.
Just had a contact with VK2KFJ, Steve who was mobile and I can report that this antenna is working very nicely for me. The current set up is purely experimental and will need some work to survive the weather.