I encouraged Ken to buy a WSPRlite last week, and we had a brief meeting on 30m where his triple loop array could run against my single loop. Ken's construction is very careful and considered, as he has a long career in electronics enginnering.
This is how the loops, running 200mW, compared. My single turn, 28mm copper pipe loop is in blue, Ken's triple, 15mm pipe loop in red:
In terms of the average distance achieved, the two loops were identical, coming in on that day at 6.6% of the maximum possible (antipodan) distance. Ken's loop managed a greater distance periodically.
Overall, there isn't an awful lot to choose between the two loops, but it's clearly worth adding a bit more metal if you can manage it.
The question of whether a loop is any good and can keep up with full-sized antennas is one that is dominated by each antenna's environment.
For example, here's the week-long loop run against a
Clearly, the loop does better than this particular doublet by all measures during the whole run. Notably, the loop keeps going through the night, whereas the
Here's a comparison with an inverted-L, tuned at the base:
The loop is not quite as good as the inverted-L, but it does very well, nevertheless, especially when one considers the difference in physical size and the simplicity with which a loop can be installed.
And, finally, few people have anything bad to say about a loft dipole. Yet, many criticise magnetic loops as just 'dummy loads'. Here's why that view is utterly misguided:
Again, and whilst the loft dipole wasn't running some of the time, the magnetic loop does better at all points.
So the message is always the same: a well-made magnetic loop in a good, clear environment can do as well as or better than full-sized wire antennas in many cases.