I got curious about mag loops (or STLs as some say they are more appropriately called - Small Transmitting Loops) a few years back and did some reading. Once I understood the theory vis-a-vis the 'golden triangle of antennas ( efficiency, small size, wide bandwidth - pick TWO) it made sense and I desired to try them out. So I first got an MFJ-935B and made some loops out of copper tubing and experimented. Not enough though, I am afraid... but what I did do showed very promising results.
When we moved cross country and into an apartment I took a certain government check sent to everyone and handed it over for an MFJ-1786 to use at the apartment we had rented. Unfortunately again, my 'play' was cut short by some very sensitive AFCI breakers. And once we were able to buy a house and move in, I found the numerous trees around to be good supports for wire antennas. One of which I built was a set of vertical wires with the feedpoint mounted at the top of a wooden fence going up to a tree limb. Each band had two radials going down the back side of the fence, spaced the same distance apart as the vertical portion. This is a very good, well tuned antenna that talks all over the world.
So... after finding a good deal on a reliable TV rotor I had used before AND being bored, I decided to get the MFJ-1786 out of storage and do some experimenting. I mounted 3' tripod on a weighted down wood pallet in the yard with a 4' mast that had the rotor and a lateral support bearing mounted to it. Then I went up with a typical 4.5' TV mast to the loop. All-in-all it was about 8 foot above ground and rotatable. Let the fun begin!
What did I discover? Well, first thing I did on the antenna was work a Malawi DXpedition on 10m FT8 that I had been unsuccessful up until then with my vertical wires. This can be attributed to other things, of course, but I did a lot of A/B testing after that. Bottom line, if I point the 'end' of the loop at a station, I would observe 2 S units better reception over the vertical wires and a 2-3 S unit decrease when I aimed the broadside nulls at the same station. This repeated fairly consistently. BUT... the wires seemed to be much quieter than the loop, thus negating the 'advantage' when aimed at a station. This was atmospheric noise and not local noise. However, if I DID have say, some local electrical noise or RFI, aiming the loop with the null towards the noise would be a great advantage to working some stations.
My original hope was to use the 'directional advantage' of the loop to aid me in working DX stations. But the noise difference seems to make it a draw and the loop has no advantage,
thus far, over the wires. What I have NOT experimented with enough is issues of take off angle... local versus distance, etc. I have a 20 ft cliff and then a metal barn just beyond the edge on top of that cliff/rise which is only about 50 feet behind my wires to the south. I would like to use the loop to work more SA on 10m and see if it helps with a higher angle due to reflection off the nearby ground.
So, there may yet be some advantages to the loop I don't yet know about. BUT, I have recently purchased a lightweight 6m yagi and may use a second slip on mast and put the yagi up in place of the loop. So, no telling if/when I will get around to experimenting more. But MAKE NOTE. I am not taking down the loop because it is not a good antenna... I am taking it down because it is NO BETTER than my vertical wire antennas. It is a GOOD antenna, in spite of what some think because of it's size.
The 'triangle' I mentioned... pick two? Obviously, it's Efficiency and Small size. The Bandwidth is VERY narrow... BUT it's remote tunable!!! So that makes up somewhat for the narrow bandwidth curve. It would not be a great 'scan the bands' antenna... but it a day & time when modes like FT8 & FT4 are popular, one can tune up on a band and sit there for hours watching/working other stations. Or occasionally QSY to another band. I seem to be able to do that to a nearby band within a cycle or two (30 seconds). Going from 30m to 10m or vice versa might take a little longer.
Enjoy your loop! I highly recommend that if you mount it horizontal, put it 20 feet or more above ground... if vertical, leave it rotatable, whether remotely with a small rotor or armstrong by hand.

As always... your mileage may vary.

Wow! 6m is open... wish I had the beam up already!
