Circularly polarized antennas and wearable devices
Provided are a circularly polarized antenna and a wearable device. The circularly polarized antenna is applicable to a wearable device, the antenna including: an annular gap structure including 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 feeding terminal connected across the gap structure, electrically connected to the radiator at one end, and connected to a feeding module of a mainboard of the wearable device at the other end; and at least one first grounding terminal connected across the gap structure, electrically connected to the radiator at one end, and electrically connected to a grounding module of the mainboard via an inductor at the other end.
1. 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.
2. The circularly polarized antenna according to claim 1 , wherein
a line connected between the single feeding terminal and a center point of the radiator is a first connecting line, and a line connected between the at least one first grounding terminal and the center point of the radiator is a second connecting line, and a first included angle α is formed from the first connecting line to the second connecting line along a first direction;
the first direction is a clockwise direction around the radiator; and
α
∈
(
0
,
π
2
)
⋃
(
π
,
3
π
2
)
.
3. The circularly polarized antenna according to claim 1 , further comprising:
at least one second grounding terminal electrically connected to the radiator a first end, and electrically connected to the grounding module of the mainboard via a capacitor at a second end.
4. The circularly polarized antenna according to claim 3 , wherein the capacitor comprises a transient voltage suppressor (TVS).
5. The circularly polarized antenna according to claim 1 , wherein the gap structure comprises a gap formed between the radiator and the mainboard.
6. The circularly polarized antenna according to claim 1 , wherein
the radiator comprises a metal bezel of the wearable device.
7. The circularly polarized antenna according to claim 6 , wherein the gap structure comprises a gap formed between the metal bezel and a metal middle frame of the wearable device.
8. The circularly polarized antenna according to claim 1 , wherein the radiator comprises a metal middle frame of the wearable device.
9. The circularly polarized antenna according to claim 1 , wherein:
an inherent resonant frequency corresponding to a physical perimeter of the radiator is less than the central operating frequency of the circularly polarized antenna.
10. A wearable device, comprising the circularly polarized antenna according to claim 1 and a housing in which the mainboard is disposed, wherein the radiator comprises at least a part of the housing.
11. The wearable device according to claim 10 , wherein the housing comprises a middle frame, a bottom case, and an annular metal bezel fixedly disposed on an end surface of the middle frame away from the bottom case, wherein the radiator comprises the annular metal bezel.
12. The wearable device according to claim 11 , further comprising:
a second antenna disposed on the mainboard, the second antenna having a radiation branch coupled to the annular metal bezel.
13. The wearable device according to claim 11 , wherein the middle frame is made of a metallic material, and an insulating layer is provided between the middle frame and the annular metal bezel.
14. The wearable device according to claim 10 , wherein the housing comprises a metal middle frame and a non-metallic bottom case, wherein the radiator comprises the metal middle frame.
15. The wearable device according to claim 10 , wherein
the inductor is configured to adjust a resonant frequency of the circularly polarized antenna to the central operating frequency of the circularly polarized antenna.
16. The wearable device according to claim 10 , wherein the circularly polarized antenna further comprises:
at least one second grounding terminal electrically and mechanically connected to the radiator at a first end, and to the grounding module of the mainboard via a capacitor at a second end.
17. A wearable device, comprising:
a circuit board, comprising a feeding module and a grounding module; and
a 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 circuit board; 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 and in direct contact with a first end of an inductor, wherein a second end of the inductor is directly connected to the grounding module of the circuit board,
wherein a current phase difference is formed between the first end of the single feeding terminal and the first end of the at least one first grounding terminal, so as to generate a rotating current in the radiator for circular polarization.
18. The wearable device according to claim 17 , further comprising:
a housing, wherein the radiator comprises at least a part of the housing.
19. The wearable device according to claim 17 , wherein the gap structure comprises a gap formed between the radiator and the circuit board.
20. The wearable device according to claim 17 , wherein the radiator comprises a bezel of the wearable device, and the gap structure comprises a gap formed between the bezel and a middle frame of the wearable device.