I'm considering building multi-turn wire loop receive antennas for a blitzortung.org lightning detection receiver. It has three separate channels for H-field antennas, operating simultaneously.
Typically, only two orthogonal loops in vertical planes are made and co-located, e.g like:
Having enough real estate available this time, I wonder if there could be any advantage in placing loops several meters apart. Aren't directional nulls suffering from the close neighbour - other loop? (possibly resulting in a poorer SNR for the given loop, if a near noise source would be otherwise in a deeper directional null)
Same question applies for adding a third, horizontal loop. Are there any advantages in not using the same mechanical frame? When co-locating, is there anything about the feeder routing to consider? (extremely: one could route the feeder of horizontal loop in question right along the side of a vertical loop).
I saw three colocated orthogonal loops elsewhere, but that was quite a different application. There, only one of loops is connected to the receiver, others are open-circuit.
And lastly, would same considerations (from the answers to come) apply if shielded loops are used?