Circularly polarized antennas and wearable devices

A circularly polarized antenna, applicable to a wearable device comprising a mainboard, the mainboard comprising a feeding module and a grounding module, and the circularly polarized antenna comprising:

• an annular gap structure comprising an annular antenna radiator, the radiator having an effective perimeter equal to a wavelength corresponding to a central operating frequency of the circularly polarized antenna;
• a single feeding terminal-connected across the gap structure, having a first end electrically connected to and in direct contact with the radiator and a second end electrically connected to and in direct contact with the feeding module of the mainboard;
• and
• at least one first grounding terminal connected across the gap structure, having a first end electrically connected to and in direct contact with the radiator and a second end electrically connected to the grounding module of the mainboard solely through an inductor, wherein a rotating current is to be generated for circular polarization by directly connecting the single feeding terminal and the feeding module of the mainboard, and connecting the at least one grounding terminal to the grounding module of the mainboard solely through the inductor.