After I had a variable capacitor, I thought I'd go ahead and try my hand at a magnetic loop antenna. This used 15 feet of RG58u I had sitting around that I wasn't going to use (as it was kind of chewed up from having been caught in a door a few times - used the good parts that were left). Used a 3 foot length for the coupling loop. Have the cap hanging from a hook at the top, have the coax zip-tied to it. Using some PVC pipe I had laying around for the mast/shape, and have that one a little base I had printed for a e-drum I made at some point.
I made this for 20m, but couldn't get that to tune. The lowest capacitance I have seems to be too much. I might try putting in a cap in series to tune down (if I have any 500v ones sitting around). But for now I tried 30/40m. I was using 1W (as I wasn't sure about the voltage the cap could handle, plus I was using this in my garage...), and didn't really get anywhere on wspr on 40m (got picked up in the immediate area, but no farther). But on 30m, did ok
Tuning it is *hard*. Just barely turning the knob moves the SWR dip a *lot*.
This was a fun experiment. I don't really see using it much, but might play with it some more at some point. Definitely felt like I learned a bit along the way.