I've tried some experiments in my spare time, although it's not a priority here with terminated loop antennas already performing well.  Necessity is the mother of invention as they say.  Anyway, my experiments have been with a single ferrite loopstick which keeps the monetary investment low.  I assume that if I can widen the bandwidth using a single loopstick, then it would be a relatively simple matter to transfer the design to a higher gain FSL.

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