Ferrite vs Air Core Ferrite loops should be very familiar to us, since even the simplest pocket MW receiver uses one. They also incorporate an amplifier to increase the signals. Some commercial designs are made by McKay Dymek, Radio West and Palomar Engineers. The Radio West design uses a 19 inch ferrite bar made up of several smaller rods, epoxied together. This design is very compact compared to a 3 foot square air core loop.
Performance can be as good or better than the ferrite types.
The first step is to study the accompanying sketches to see if you can make any sense out of them. I used 2x2 inch cedar for all parts of the loop, since it is strong, light, attractive and resistent to warping etc. The crosspieces are notched at the center so they fit together snugly. This fits snugly inside a length of 1.5 inch black ABS plastic plumbing pipe. Use a cap on the bottom.