It’s a bit more strange than that… check these photos; XLED implantable field detector - #30 by Jesse
It is basically an expanding spiral coil, but along the sides the wire is overlapping itself almost vertically… at least it’s very hard to keep it from folding or sliding over itself on those sides when you are trying to carefully extract it from the melted plastic and then re-encapsulate it. Here’s an extraction from IAR for example;
yes you could technically manipulate the fragile and finicky copper wire to basically create protections against this… but ultimately the labor involved in conversion is already pretty high… I’d rather the PCB antenna solution so I can just mishandle the copper wire during extraction, then toss it away.
We are already working on a “mega” style disc antenna for 70pF icard and purewrist chips… and there is a narrow vimpay pcb antenna in the works as well. It wouldn’t take much at this point to make a mega style antenna for vimpay chips too.