I just disassembled an external FM antenna designed for an old Asus laptop.
I expected to find some circuitry and a monopole or some other simple antenna. However, what I found was the antenna shown in the picture (bottom and top view). Honestly, it resembles somewhat a monopole because there is a ground plane and only one side of the wire is connected to the coaxial cable that exited from the case of the antenna. But I can't explain why it has that strange shape.
I should add that the bottom of the pcb was in contact (or maybe just really close) to two magnets.
- What kind of antenna is that and how does it work? (or where I can find how it works)
- What was the purpose of the two magnets?
- Why the is the wire shaped like that? And why is the ground plane shaped too? (see the bottom view)