What can be useful here is 22mm blue PVC water pipe, intended for underground use. Builder's merchants keep huge coils of it, conveniently of ~1m diameter.
It's cheap and it weighs little, so a single loop of it gives you the structure for use with a rotator, even if you use it with no more than a single strand of wire passing through it.
David; are you really sure that at higher frequencies (>2MHz) loop "thickness" i.e. wire v tube is not significant on receive?
I note that in some articles on loops, the term "fat loops" has crept in
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B