Circularly polarized antenna and wearable device

Abstract

The invention relates to the technical field of intelligent wearable devices, and specifically provides a circularly polarized antenna and a wearable device. The antenna comprises an annular slot structure, wherein the slot structure comprises an annular metal radiator; the feed terminal is bridged to the slot structure, one end of the feed terminal is electrically connected with the metal radiator, and the other end of the feed terminal is connected with a feed module of the mainboard; and the at least one first grounding terminal is bridged to the gap structure, one end of the first grounding terminal is electrically connected with the metal radiator, and the other end of the first grounding terminal is electrically connected with a grounding module of the mainboard through an inductor. The antenna can realize circular polarization of wearable devices of different sizes, is simple in structure, greatly simplifies the structure of the circularly polarized antenna, reduces the design cost, and can improve the application adaptability and flexibility.

Description

[0001] Case Separation Statement This application is a divisional application of Chinese invention patent application No. 202011051024.1, filed on September 29, 2020, entitled "Circularly Polarized Antenna and Wearable Device". Technical Field

[0002] This disclosure relates to the field of smart wearable device technology, specifically to a circularly polarized antenna and a wearable device. Background Technology

[0003] With the development of smart wearable devices, satellite positioning has become one of their most important functions. To achieve satellite positioning and trajectory recording, satellite positioning antennas are indispensable. To enhance the transmission efficiency from satellite to the ground (e.g., to improve penetration and coverage), the satellite's transmitting antenna to the ground adopts circular polarization. Similarly, to enhance the receiving capability of the positioning antenna, the receiving antenna of the device should also adopt the same circular polarization as the transmitting antenna.

[0004] However, due to size or industrial design limitations, smart wearable devices generally use linearly polarized antennas instead of circularly polarized antennas. This results in poor satellite positioning performance. For example, when users are in complex environments such as under the shade of trees, the antenna's reception efficiency for satellite signals is low, leading to inaccurate positioning and motion trajectory tracking. Summary of the Invention

[0005] To improve the satellite positioning accuracy of smart wearable devices, this disclosure provides a circularly polarized antenna and a wearable device.

[0006] In a first aspect, embodiments of this disclosure provide a circularly polarized antenna for a wearable device, comprising: An annular slit structure, the slit structure comprising an annular radiator; The motherboard includes a power supply module and a grounding module; A power supply terminal is connected across the slot structure, one end of which is directly connected to the annular radiator, and the other end is connected to the power supply module; and At least one first grounding terminal is connected across the slot structure, one end of the first grounding terminal is electrically connected to the annular radiator, and the other end is connected to the grounding module through an inductor assembly.

[0007] In some embodiments, the gap structure is formed by a gap between the motherboard and the annular radiator.

[0008] In some embodiments, the housing of the wearable device includes a bottom shell and a middle frame, at least a portion of the middle frame forming the annular radiator.

[0009] In some embodiments, the housing of the wearable device includes a mid-frame and a front frame, at least a portion of which forms the annular radiator.

[0010] In some embodiments, the housing of the wearable device includes a mid-frame and a front frame, with the gap between the mid-frame and the front frame forming the gap structure.

[0011] In some embodiments, the gap structure between the middle frame and the front frame is provided with an insulating layer.

[0012] In some embodiments, one end of the power supply terminal is connected to the front frame and the other end is connected to the power supply module of the motherboard, and one end of the at least one first ground terminal is connected to the middle frame and the other end is connected to the ground module of the motherboard.

[0013] In some embodiments, the effective length of the annular radiator is equal to the wavelength of the wireless signal transmitted and received by the circularly polarized antenna.

[0014] In some embodiments, the slit structure is a closed ring structure with the ends connected.

[0015] In some embodiments, where the at least one first grounding terminal includes a plurality of first grounding terminals, the plurality of first grounding terminals are arranged circumferentially along the slot structure.

[0016] In some embodiments, the inductor assembly is used to draw current on the annular radiator to generate a rotating annular current in the annular radiator.

[0017] In some embodiments, the line connecting the power supply terminal and the center of the annular radiator is a first line, the line connecting the first ground terminal and the center of the annular radiator is a second line, the clockwise circumferential direction of the annular radiator is a first direction, and along the first direction, the first line and the second line form a first angle. ; in, The inductor component causes a right-handed current to be generated on the ring radiator, or... The inductor component causes a left-handed current to be generated on the annular radiator.

[0018] In some embodiments, the circularly polarized antenna further includes at least one second grounding terminal, which is connected across the slot structure. One end of the second grounding terminal is electrically connected to the annular radiator, and the other end is connected to the grounding module via a capacitor assembly.

[0019] In some embodiments, the capacitor assembly is used to draw current on the annular radiator to generate a rotating annular current in the annular radiator.

[0020] In some embodiments, the line connecting the power supply terminal and the center of the annular radiator is a first line, the line connecting the second ground terminal and the center of the annular radiator is a third line, the counterclockwise rotation direction of the annular radiator is a second direction, and along the second direction, the first line and the third line form a second angle. β ; in, The capacitor assembly causes a right-handed current to be generated on the annular radiator; or, The capacitor assembly causes a left-handed current to be generated on the annular radiator.

[0021] In some embodiments, the at least one first grounding terminal and the at least one second grounding terminal are arranged circumferentially along the slot structure.

[0022] In some embodiments, when the at least one second grounding terminal includes a plurality of second grounding terminals, the plurality of second grounding terminals are arranged circumferentially along the slot structure.

[0023] In some embodiments, the polarization direction of the circularly polarized antenna depends on the superposition of the inductive pulling capability of the inductor component and the capacitive pulling capability of the capacitor component. The polarization direction of the circularly polarized antenna includes: left-hand circular polarization and right-hand circular polarization. The inductive pulling capability of the inductor component and the polarization direction corresponding to the capacitive pulling capability of the capacitor component are the same, and the polarization direction of the circularly polarized antenna is the polarization direction corresponding to either the inductive pulling capability or the capacitive pulling capability. or, The inductive pulling capability of the inductor component corresponds to the opposite polarization direction to the capacitive pulling capability of the capacitor component, and the polarization direction of the circularly polarized antenna is the polarization direction corresponding to the larger of the inductive pulling capability and the capacitive pulling capability.

[0024] In some embodiments, the housing and display module of the wearable device form a receiving space, the motherboard is disposed within the receiving space, and at least a portion of the housing forms the annular radiator.

[0025] In some embodiments, the housing includes a front frame, a middle frame, and a bottom shell. The front frame is fixed to the end face of the middle frame away from the bottom shell, and the gap structure is formed between the front frame and the motherboard. The front frame forms the annular radiator.

[0026] In some embodiments, the housing of the wearable device includes a bottom shell and a middle frame, the motherboard is disposed inside the housing, and the gap structure is formed between the motherboard and the middle frame, the middle frame forming the annular radiator.

[0027] In some embodiments, the housing of the wearable device includes a face frame, a middle frame, and a bottom shell. The middle frame is electrically connected to the grounding module of the motherboard. The face frame is fixed on the end face of the middle frame away from the bottom shell. An insulating layer is provided between the middle frame and the face frame to form the gap structure between the middle frame and the metal face frame. The metal face frame forms the annular radiator.

[0028] Secondly, embodiments of this specification provide a wearable device including a circularly polarized antenna according to any embodiment of the first aspect.

[0029] In some embodiments, the wearable device is a wrist-worn device.

[0030] The circularly polarized antenna disclosed herein, applied to wearable devices, includes a ring-shaped slot structure. The slot structure includes a ring-shaped metal radiator, the effective circumference of which is equal to one wavelength of the antenna's center operating frequency. A feed terminal is connected across the slot of the slot structure. The antenna also includes at least one first ground terminal, one end of which is electrically connected to the radiator, and the other end is electrically connected to the grounding module of the motherboard via an inductor. The inductor pulls current onto the radiator, causing the ring-shaped radiator to generate a rotating effective ring current, thereby forming a circularly polarized wave and realizing a circularly polarized antenna. Compared to linearly polarized antennas, circularly polarized antennas have higher receiving efficiency, resulting in more accurate satellite positioning. Furthermore, by directly feeding the radiator to form the circularly polarized antenna structure, no other coupling structures are required, greatly simplifying the structure and reducing the cost of the circularly polarized antenna, making it easier to implement in smaller smart wearable devices. Moreover, grounding via an inductor reduces the effective electrical length of the antenna structure, allowing for higher operating frequencies using a larger antenna structure, providing more possibilities for the design of circularly polarized antennas.

[0031] The circularly polarized antenna provided in this disclosure has a first connection line between the feed terminal and the center point of the radiator, and a second connection line between the first ground terminal and the center point of the radiator. The clockwise angle between the first and second connections is the first included angle. By adjusting the size of the first included angle, i.e., changing the position of the inductor, circularly polarized antennas in different directions can be realized. When the first included angle is 0°~90° or 180°~270°, the current in the radiator rotates counterclockwise, thus forming a right-hand circularly polarized antenna; when the first included angle is 90°~180° or 270°~360°, the current in the radiator rotates clockwise, thus forming a left-hand circularly polarized antenna. The antenna structure of this disclosure can realize circularly polarized waves in different directions by adjusting the first included angle, meeting the design requirements of circularly polarized antennas in different directions. Furthermore, an antenna structure that achieves circular polarization with one inductor can be equivalent to an antenna structure formed by multiple inductors with different angles and inductance values, thereby enabling the design of more complex circularly polarized antenna structures using multiple first ground terminals.

[0032] The circularly polarized antenna provided in this embodiment further includes at least one second grounding terminal. One end of the second grounding terminal is electrically connected to the radiator, and the other end is electrically connected to the grounding module of the motherboard via a capacitor. The capacitor draws current into the radiator, causing the circular radiator to generate an effective rotating circular current, thereby forming a circularly polarized wave and realizing a circularly polarized antenna. Furthermore, the current-drawing capabilities of the capacitor and inductor can be superimposed, allowing for the simultaneous use of both capacitors and inductors in the design of a circularly polarized antenna, providing more possibilities for its design.

[0033] The circularly polarized antenna structure provided in this disclosure has a first connection line between the feed terminal and the center point of the radiator, a third connection line between the second ground terminal and the center point of the radiator, and a second angle between the counterclockwise direction of the first and third connection lines. By adjusting the size of the second angle, i.e., changing the position of the capacitor, circularly polarized antennas in different directions can be achieved. The second angle is opposite in direction to the first angle, meaning the capacitor and inductor have opposite effects. When the second angle is 0°~90° or 180°~270°, the current in the radiator rotates counterclockwise, thus forming a right-hand circularly polarized antenna; when the second angle is 90°~180° or 270°~360°, the current in the radiator rotates clockwise, thus forming a left-hand circularly polarized antenna. Furthermore, an antenna structure that achieves circular polarization with a single capacitor can be equivalent to an antenna structure formed by multiple capacitors with different angles and capacitance values, thereby enabling the design of more complex circularly polarized antenna structures using multiple second ground terminals.

[0034] The wearable device of this disclosure includes the circularly polarized antenna described in the above embodiments, and therefore possesses all the aforementioned beneficial effects. Furthermore, the metal faceplate or mid-frame of the wearable device can be used to form the radiator. On one hand, the metal faceplate or mid-frame can serve as a decorative structure for the watch, improving its aesthetics; on the other hand, using the metal faceplate or mid-frame as the radiator reduces the space occupied by the antenna structure within the watch, and a larger radiator significantly enhances the antenna's radiation performance. In addition, the combined ground return scheme proposed in this disclosure is applicable to situations where the original inherent resonant frequency of the antenna radiator is less than or greater than the GPS operating frequency of 1.575 GHz. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments or technical solutions in the prior art of this specification, the accompanying drawings used in the description of the specific embodiments or prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this specification. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a circularly polarized antenna structure according to some embodiments of this disclosure.

[0037] Figure 2 This is a schematic diagram of a circularly polarized antenna structure according to other embodiments of this disclosure.

[0038] Figure 3 This is a schematic diagram of a circularly polarized antenna structure according to some embodiments of this disclosure.

[0039] Figure 4 This is a schematic diagram of a circularly polarized antenna structure according to other embodiments of this disclosure.

[0040] Figure 5 This is a graph showing the axial ratio of the antenna as a function of the capacitance value in one embodiment of this disclosure.

[0041] Figure 6 This is a graph showing the axial ratio variation of an antenna according to one embodiment of the present disclosure.

[0042] Figure 7 This is a graph showing the axial ratio of an antenna as a function of inductance value according to one embodiment of the present disclosure.

[0043] Figure 8 This is a graph showing the axial ratio of an antenna as a function of inductance value according to one embodiment of the present disclosure.

[0044] Figure 9 This is a radiation gain diagram of an antenna structure according to one embodiment of the present disclosure.

[0045] Figure 10 This is an exploded structural diagram of a wearable device according to one embodiment of the present disclosure.

[0046] Figure 11 This is a cross-sectional view of the assembly structure of a wearable device according to one embodiment of the present disclosure.

[0047] Figure 12 This is a schematic diagram of the structure of a GPS antenna according to one embodiment of the present disclosure.

[0048] Figure 13 This is a curve showing the change in the axial ratio of an antenna as a function of frequency according to one embodiment of this disclosure.

[0049] Figure 14 This is a curve showing the change of return loss of an antenna with frequency according to one embodiment of the present disclosure.

[0050] Figure 15 This is a curve showing the antenna efficiency as a function of frequency according to one embodiment of the present disclosure.

[0051] Figure 16 This is the gain curve of the antenna in the XOZ plane according to one embodiment of the present disclosure.

[0052] Figure 17 This is the gain curve of the antenna in the YOZ plane according to one embodiment of the present disclosure.

[0053] Figure 18 This is the radiation pattern of the antenna in the XOZ plane according to one embodiment of the present disclosure.

[0054] Figure 19 This is the radiation pattern of the antenna in the YOZ plane according to one embodiment of the present disclosure.

[0055] Figure 20 This is an exploded structural diagram of a wearable device according to another embodiment of this disclosure.

[0056] Figure 21 This is a cross-sectional view of the assembly structure of a wearable device according to another embodiment of this disclosure.

[0057] Figure 22 This is a curve showing the change in the axial ratio of the antenna as a function of frequency according to another embodiment of this disclosure.

[0058] Figure 23 This is a curve showing the change in return loss of the antenna as a function of frequency according to another embodiment of this disclosure.

[0059] Figure 24 This is a curve showing the antenna efficiency as a function of frequency according to another embodiment of the present disclosure.

[0060] Figure 25 This is the gain curve of the antenna in the XOZ plane according to another embodiment of this disclosure.

[0061] Figure 26 This is the gain curve of the antenna in the YOZ plane according to another embodiment of this disclosure.

[0062] Figure 27 This is the radiation pattern of the antenna in the XOZ plane according to another embodiment of this disclosure.

[0063] Figure 28 This is the radiation pattern of the antenna in the YOZ plane according to another embodiment of this disclosure.

[0064] Figure 29 This is an assembly cross-sectional view of an antenna structure according to one embodiment of the present disclosure.

[0065] Figure 30 This is a schematic diagram of an antenna structure according to another embodiment of the present disclosure.

[0066] Figure 31 This is a schematic diagram of an antenna structure according to another embodiment of the present disclosure. Detailed Implementation

[0067] The technical solutions of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification. Furthermore, the technical features involved in the different embodiments of this specification described below can be combined with each other as long as they do not conflict with each other.

[0068] Circularly polarized antennas are widely used in satellite navigation systems because the circularly polarized waves they generate can be received by linearly polarized antennas in any direction, and they can also receive incoming waves of any linear polarization. They possess excellent antenna performance, making them commonly used in satellite positioning and reconnaissance / jamming operations. Compared to linearly polarized antennas, the main advantages of circularly polarized antennas are approximately a 3dB improvement in satellite signal strength received by ground equipment while maintaining comparable antenna efficiency; they also enhance the anti-jamming capability of the satellite positioning system in complex environments, leading to more accurate positioning and trajectory tracking.

[0069] Circularly polarized antennas can be divided into left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). Taking satellite positioning antennas as an example, the world's major satellite navigation and positioning systems, including GPS, BeiDou, GLONASS, and Galileo, all use right-hand circular polarization for civilian satellite positioning.

[0070] With the development of smart wearable devices, satellite positioning has become an essential function. Taking smartwatches as an example, satellite positioning can be used for various applications such as motion assistance, trajectory detection, and location tracking. In commercially available wearable devices, satellite positioning antennas are mostly implemented using linearly polarized antennas, such as IFA and slot antennas. However, as mentioned earlier, linearly polarized antennas have low efficiency in receiving circularly polarized waves emitted by satellites. This results in poor positioning accuracy and trajectory detection performance for wearable devices, making it difficult to meet the requirements for high-accuracy positioning.

[0071] To address the aforementioned issues, some smartwatches in related technologies employ circularly polarized antennas to implement satellite positioning antennas.

[0072] One known scheme (Chinese Patent Publication No.: CN104051865 A) achieves circular polarization antenna performance by feeding an inverted-F antenna (IFA) below the metal ring on the upper surface of the watch and coupling it to the metal ring via another parasitic antenna element (the parasitic element being the grounded branch on the side of the IFA). In this circular polarization design, to generate a loop current on the metal ring, the current drawn onto the metal ring can only present an effective loop current if the lengths of the IFA antenna and the parasitic element, as well as the gaps between them and the metal ring, meet certain requirements. The "effective loop current" here refers to the generated loop current being able to circulate relatively uniformly along the metal ring with changes in phase, so that the axial ratio of the circular polarization antenna can reach 3dB or less.

[0073] Another known solution (Chinese Patent Publication No.: CN 110994131 A) omits the parasitic element compared to the above solution, that is, it only uses a fed IFA antenna and the watch metal ring coupling to achieve circular polarization. Although this solution simplifies some structures, its principle is similar to the above solution; the ring current on the metal ring is achieved through the coupling between the IFA antenna (and the parasitic element) and the metal ring. Therefore, both of the above known solutions have special requirements on the length of the IFA antenna, the parasitic element, and the watch metal ring, as well as the gaps between them, which undoubtedly increases the difficulty of antenna design. Moreover, in the above two known solutions, the IFA antenna (and the parasitic element) is an FPC or LDS antenna placed on an antenna support, which undoubtedly occupies the limited space of the watch, making it difficult to apply to wearable devices with limited space. In addition, the circularly polarized antennas in the above two known solutions are only suitable for situations where the original or inherent resonant frequency of the antenna radiator itself is greater than the GPS operating frequency of 1.575 GHz, which has poor applicability. A detailed explanation is given below and will not be elaborated here.

[0074] Based on the deficiencies of the aforementioned related technologies, this disclosure provides a simple and effective circularly polarized antenna that can be used in smart wearable devices to achieve a circularly polarized antenna configuration. Specifically, the circularly polarized antenna proposed in this disclosure is applicable when the original or inherent resonant frequency of the antenna radiator is less than or greater than the GPS operating frequency of 1.575 GHz.

[0075] It is understood that the smart wearable devices described in the following embodiments of this disclosure can be any suitable form of device, such as smartwatches, smart bracelets and other watch-type devices; smart glasses, VR glasses, AR glasses and other glass-type devices; smart clothing, smart headphones, wearable devices and so on; and this disclosure does not limit them.

[0076] In some embodiments, the antenna structure of this disclosure includes an annular slot structure, for example... Figure 1 In the illustrated embodiment, the slot structure includes an annular radiator 200, which is a metallic radiator, such as a metal ring. The radiator 200 is disposed parallel to the motherboard 100 above it, with a certain gap between them. This gap forms the slot structure of the antenna, and the antenna function is achieved by feeding and grounding through this gap. Furthermore, in this embodiment, the periphery of the motherboard 100 and the annular radiator 200 have similar shapes, thereby forming a relatively uniform and complete annular slot between the motherboard 100 and the radiator 200.

[0077] The mainboard 100 is the device's main PCB (Printed Circuit Board), which integrates a processor and corresponding control circuit modules (not shown in the attached diagram). The radiator 200 is a ring-shaped metal radiator, such as a metal ring, and is positioned above the mainboard 100, thus forming a gap between the radiator 200 and the mainboard 100. The radiator 200 is electrically connected to the mainboard 100 via a feed terminal 110 and at least one first ground terminal 120. The feed terminal 110 is connected to the feed module of the mainboard at a feed point 111, and the ground terminal 120 is connected to the ground module of the mainboard via an inductor 121, thereby forming an antenna structure.

[0078] The power supply terminal 110 spans the gap between the motherboard 100 and the radiator 200. That is, one end of the power supply terminal 110 is electrically connected to the radiator 200, and the other end is connected to the power supply module of the motherboard 100. It is understood that the connection between the power supply terminal 110 and the radiator 200 can be an electrical connection formed by connecting components or an integral molding; this disclosure does not impose any limitations on this. In one example, the power supply terminal 110 is integrally molded with the radiator 200, and its free end is electrically connected to the power supply module of the motherboard 100 through a spring contact structure or a pop pin structure on the motherboard 100. The location where the power supply terminal 110 connects to the motherboard 100 forms a power supply point 111.

[0079] Continue to refer to Figure 1 In this embodiment, only one first grounding terminal 120 is shown. The first grounding terminal 120 is connected across the gap formed between the motherboard 100 and the radiator 200. That is, one end of the first grounding terminal 120 is electrically connected to the radiator 200, and the other end is connected to the grounding module of the motherboard 100. It can be understood that the connection between the grounding terminal 120 and the radiator 200 can be an electrical connection formed by connecting components, or it can be integrally formed. This disclosure does not limit this.

[0080] The first grounding terminal 120 is connected to an inductor 121, and the radiator 200 is grounded through the inductor 121. Specifically, the inductor 121 can be installed on the motherboard 100, with one end connected to one end of the first grounding terminal 120 and the other end connected to the grounding module of the motherboard 100. It is worth noting that the grounding module of the motherboard 100 described in this disclosure refers to the PCB board of the device, and the PCB board is the ground of the entire system.

[0081] It is understood that there can be multiple first grounding terminals 120. The following text will provide a detailed description of the scheme with multiple first grounding terminals 120, but will not be described in detail here.

[0082] For a circularly polarized antenna with a ring radiator, the effective perimeter of the radiator is equal to one wavelength of the antenna's center operating frequency. Therefore, when implementing antennas for different frequencies, it is necessary to set the effective perimeter of the radiator to be equal to one wavelength of that frequency.

[0083] It's worth noting that in free space, the physical perimeter of the radiator 200's circumference is its effective perimeter. However, in an assembled structure, the assembly structure and surrounding materials of the radiator 200 increase its effective perimeter, thus decreasing its resonant frequency. For example, when the radiator 200 is assembled with a plastic material (such as a plastic support or nano-injection molding material), this material increases the radiator's effective perimeter. Similarly, screens near the radiator 200 also contribute to increasing its effective perimeter, such as the glass cover of a screen assembly.

[0084] The effective perimeter of the radiator 200 is increased because the dielectric constants of the plastic material and the glass cover (the dielectric constants of plastic and nano-injection molded materials are generally between 2 and 3, and the dielectric constants of the glass cover are generally between 6 and 8) are greater than those of air. The introduction of materials with high dielectric constants will increase the current intensity near the radiator, thereby increasing the effective length of the radiator 200. Therefore, using a smaller actual physical perimeter of the radiator 200 can achieve antenna resonance at a lower actual physical length; that is, the actual physical perimeter of the radiator 200 can be reduced while achieving the same resonant frequency. Therefore, those skilled in the art will understand that the "effective perimeter" described in the embodiments of this disclosure refers to the effective electrical length of the radiator that actually generates resonant electromagnetic waves, and is not limited to the understanding of physical length.

[0085] In this embodiment, the radiator 200 is a ring-shaped structure. In other embodiments, the radiator 200 can also be any other suitable ring structure, such as a triangular ring, a rhomboid ring, a rectangular ring, a rounded rectangular ring, or other polygonal rings, etc. This disclosure does not limit this. In this case, the outer shape of the motherboard will change with the shape of the radiator to maintain the requirement that the outer shape of the motherboard is always similar to the shape of the radiator. Those skilled in the art will understand this, and this disclosure will not elaborate further.

[0086] At least one inventive concept of the antenna structure disclosed herein is that by directly feeding the ring radiator 200 and using a grounded inductor 121 to generate a current in the radiator 200 to pull it, a rotating ring current is formed, thereby generating a circularly polarized wave. The principle and performance of the generation of the circularly polarized wave will be described in detail below, and will not be elaborated here.

[0087] As described above, the circularly polarized antenna structure of this disclosure can realize the circularly polarized antenna form of a device, thereby achieving more accurate positioning when implementing satellite positioning functions. Furthermore, by directly feeding the ring radiator, no other coupled antenna structure is required, greatly simplifying the structure and reducing the cost of the circularly polarized antenna, making it easier to implement in devices with limited space, such as watches. Moreover, inductive grounding can reduce the effective electrical length of the antenna structure, allowing for higher operating frequencies using a larger antenna structure, providing more possibilities for the design of circularly polarized antennas. For example, when using the antenna structure of this disclosure to implement a GPS antenna for satellite positioning, this solution is applicable when the original or inherent resonant frequency of the antenna radiator itself is less than the GPS operating frequency of 1.575 GHz.

[0088] The above-described implementation achieves circular polarization by directly feeding the radiator and using inductive grounding to generate current in the radiator. However, other patents by the inventors in this case explore using a capacitor grounded to generate current in the radiator, forming a circular rotating current on the radiator, thereby achieving circular polarization.

[0089] In some implementations, such as Figure 2 As shown, the antenna structure and Figure 1 The difference in the implementation method is that instead of using the first grounding terminal 120 including inductor 121 for grounding, the second grounding terminal 130 is used for grounding through capacitor 131. For other aspects of this implementation method not described herein, please refer to the foregoing. Figure 1 The implementation method is as described above, and those skilled in the art can understand it based on the foregoing, so it will not be repeated here.

[0090] It is worth noting that, Figure 2 Only one second grounding terminal 130 is shown in this specification. In other embodiments, there may be multiple second grounding terminals 130. Moreover, the second grounding terminal 130 and the first grounding terminal 120 may be located in the same antenna structure. This will be described in detail below, and will not be elaborated here.

[0091] The following section provides a comparative explanation of the principles of circular polarization generated by capacitors and inductors, the impact of capacitors and inductors on antenna performance, and the antenna design ideas of the embodiments of this disclosure.

[0092] based on Figure 1 and Figure 2The antenna structure shown illustrates the implementation principle of the circularly polarized antenna in this embodiment. A circularly polarized antenna can be implemented in two ways: first, a rotating ring current with an effective perimeter that is an integer multiple of the wavelength can form circular polarization; second, two line currents with equal amplitude and orthogonal phase difference of 90° can form circular polarization. This embodiment implements it using the first method. For a radiator 200 with an effective perimeter of one wavelength, in this embodiment, by directly feeding the radiator 200 and effectively guiding the generated current using inductor 121 and / or capacitor 131, a rotating current field rotating in one direction is formed inside the radiator, thereby achieving a circularly polarized wave.

[0093] In addition to achieving circular polarization, inductor 121 and capacitor 131 can also affect the effective electrical length of the antenna structure. Figure 3 It shows Figure 1 The current distribution diagram of the antenna structure is shown below. Figure 3 The principle of inductive grounding is explained.

[0094] First, the line connecting the feed point 111 and the center point of the radiator 200 is defined as the first line, and the line connecting the inductor 121 and the center point of the radiator 200 is defined as the second line. The clockwise direction of the radiator 200 is defined as the first direction. The angle formed by the first line and the second line along the first direction is defined as the first angle α, that is, the first angle α is the clockwise direction.

[0095] like Figure 3 As shown, after the antenna structure is fed and grounded, since the effective length of the radiator 200 is one wavelength of the operating frequency when circular polarization is achieved, the circular rotating current generated on the radiator 200 has two current zeros, A1 and A2, and its instantaneous current distribution is shown by the arrow on the outer ring of the radiator 200. Because the current phase across the inductor lags behind the voltage phase in an AC circuit, a reverse local current is generated between the inductor 121 and the feed point 111. The local current generated by the inductor 121, after being superimposed with the current generated by the radiator 200 itself, locally weakens the current of the radiator 200. Since the current intensity of the radiator 200 is proportional to its effective electrical length, this local current will reduce the effective length of the radiator 200. Furthermore, since the resonant frequency of the radiator 200 is inversely proportional to its effective electrical length, that is, the larger the effective electrical length, the lower the resonant frequency, the resonant frequency of the radiator 200 will shift towards higher frequencies.

[0096] In one example, taking a GPS antenna for satellite positioning as an example, the center operating frequency of the GPS antenna is 1.575 GHz. Before applying inductor 121, the original or inherent resonant frequency of radiator 200 should be less than 1.575 GHz.

[0097] Figure 4 It shows Figure 2 The current distribution diagram of the antenna structure is shown below. Figure 4 The principle of capacitor grounding is explained.

[0098] Similarly, the line connecting the feed point 111 and the center point of the radiator 200 is defined as the first line, and the line connecting the capacitor 131 and the center point of the radiator 200 is defined as the third line. The counterclockwise rotation direction of the radiator 200 is defined as the second direction. The angle formed by the first line and the third line along the second direction is defined as the second angle β, that is, the second angle β is the counterclockwise direction.

[0099] like Figure 4 As shown, after the antenna structure is fed, since the effective length of the radiator 200 is one wavelength of the operating frequency, the circular rotating current generated on the radiator 200 has two current zeros, B1 and B2, and its instantaneous current distribution is shown by the arrow on the outer ring of the radiator 200. Because the current phase across the capacitor leads the voltage phase in an AC circuit, a local current in the same direction is generated between the feed point 111 and the capacitor 131. The local current generated by the capacitor 131, after being superimposed with the current generated by the radiator 200 itself, locally amplifies the current in the radiator 200. Since the current intensity of the radiator 200 is proportional to its effective electrical length, this local current will increase the effective length of the radiator 200. Furthermore, since the resonant frequency of the radiator 200 is inversely proportional to its effective electrical length (i.e., the larger the effective electrical length, the lower the resonant frequency), the resonant frequency of the radiator 200 will shift towards lower frequencies.

[0100] In one example, taking a GPS antenna for satellite positioning as an example, the center operating frequency of the GPS antenna is 1.575 GHz. Before applying capacitor 131, the original or inherent resonant frequency of the radiator 200 should be greater than 1.575 GHz.

[0101] From the above, we can draw the following conclusions: Based on circular polarization, using an inductor to return the antenna to ground can reduce its effective electrical length, while using a capacitor to return the antenna to ground can increase its effective electrical length. Based on this conclusion, more design options are available for antenna design. For example, with a larger effective circumference or diameter of a watch, an inductor to return the antenna to ground can be used to achieve a higher frequency circularly polarized antenna; conversely, with a smaller effective circumference or diameter of a watch, a capacitor to return the antenna to ground can be used to achieve a lower frequency circularly polarized antenna.

[0102] It is worth noting that the known solutions in the aforementioned related technologies are essentially equivalent to achieving circular polarization through coupling capacitor grounding. Therefore, these solutions are only applicable when the original resonant frequency of the radiator is higher than the operating frequency, and cannot be applied when the original resonant frequency of the radiator is lower than the operating frequency. This is one of the beneficial effects of the present disclosure compared to related technologies. The embodiments of the present disclosure, through inductor grounding, can be applied to cases where the original resonant frequency of the radiator is lower than the operating frequency, achieving a higher frequency circularly polarized antenna. For example, when using the antenna structure of the present disclosure to implement a GPS antenna for satellite positioning, the inductor or capacitor grounding method and the combination of them in the embodiments of the present disclosure can be applied to cases where the original resonant frequency of the radiator is higher than or lower than the GPS operating frequency of 1.575 GHz. In other words, the solution proposed in this disclosure has strong adaptability and flexibility.

[0103] Building upon the foregoing, the following section further explores the impact of the positions of the capacitor and inductor on circularly polarized antennas. (See also...) Figure 3 and Figure 4 As can be seen, since the radiator 200 has a ring structure, the position of the inductor 121 can be represented by the first included angle α, and the position of the capacitor 131 can be represented by the second included angle β. It should be noted that the directions represented by the first included angle α and the second included angle β are opposite.

[0104] First, since the condition for a ring radiator to achieve circular polarization is that the effective circumference of the radiator is equal to a wavelength of the operating frequency, according to the current distribution of the resonant wave, there must be two current zeros and two current peaks on the entire circumference (through...). Figure 3 and Figure 4 (This can also be seen). Therefore, at a certain moment, the entire radiator can be divided into four regions based on the current distribution, namely: In this region, the current rises from zero at 0° to a peak at 90°. In this region, the current drops from a peak value at 90° to zero at 180°. In this region, the current rises from zero at 180° to a peak at 270°. In this region, the current drops from a peak value of 270° to zero value of 360°.

[0105] The aforementioned current distribution is a periodic current variation distribution. Under the action of inductor 121 and capacitor 131, this periodic current distribution will rotate periodically within the ring-shaped radiator over time, thus forming a circularly polarized wave. Furthermore, when the current rotates clockwise within the radiator, a left-handed circularly polarized wave is generated, while when the current rotates counterclockwise within the radiator, a right-handed circularly polarized wave is generated.

[0106] like Figure 3 As shown, the current in the radiator 200 rotates under the action of the inductor 121, with the feed point 111 as the zero point, when the first included angle When the traction current rotates counterclockwise, the traction current rotates counterclockwise; conversely, when the first included angle... When the first angle is reached, the traction current rotates clockwise. This is because the phase of the current across inductor 121 lags behind the phase of the voltage across it in an AC circuit. Therefore, when the first angle is reached... At this time, the aforementioned phase lag will cause the current on the ring radiator 200 to rotate counterclockwise, thereby realizing a right-hand circularly polarized antenna. Similarly, when the first included angle... When the phase lag of the current across inductor 121 causes the current on the ring radiator 200 to rotate clockwise, thus realizing a left-hand circularly polarized antenna.

[0107] Furthermore, considering the characteristic that the current in a circularly polarized wave has a periodicity in the radiator when the circularly polarized wave is present, it can be concluded that... Figure 3 The circularly polarized antenna shown should satisfy the following rule: when the first included angle When the current rotates counterclockwise, it generates a right-hand circularly polarized wave; while when the first included angle... When the current rotates clockwise, it generates a left-handed circularly polarized wave. Here, "∪" represents the union of the two.

[0108] Based on the above principles, left-hand circularly polarized or right-hand circularly polarized antennas can be achieved by setting different positions of inductor 121. For example, in one example, using... Figure 3 The antenna structure shown can be used to implement a GPS antenna, and inductor 121 can be placed at the first included angle. The range is thus used to realize a right-hand circularly polarized antenna.

[0109] like Figure 4 As shown, the current in the radiator 200 rotates under the action of capacitor 131, with the feed point 111 as the zero point, when the second included angle When the traction current rotates counterclockwise, the second included angle is also counterclockwise. When the second angle is reached, the traction current rotates clockwise. This is because the phase of the current across capacitor 131 in the AC circuit leads the phase of the voltage across it; therefore, when the second angle is reached... At this time, the aforementioned phase lead will cause the current on the ring radiator 200 to rotate counterclockwise, thereby realizing a right-hand circularly polarized antenna. Similarly, when the second included angle... When the phase of the current across capacitor 131 is ahead, the current on the ring radiator 200 will rotate clockwise, thus realizing a left-hand circularly polarized antenna.

[0110] Furthermore, considering the characteristic that the current in a circularly polarized wave has a periodicity in the radiator when the circularly polarized wave is present, it can be concluded that... Figure 4 The circularly polarized antenna shown should satisfy the following rule: when the second included angle When the current rotates counterclockwise, it generates a right-hand circularly polarized wave; while when the second included angle... When the current rotates clockwise, it generates a left-handed circularly polarized wave. Here, "∪" represents the union of the two.

[0111] Based on the above principles, left-hand circularly polarized or right-hand circularly polarized antennas can be achieved by setting different positions of capacitor 131. For example, in one example, using... Figure 4 The antenna structure shown can be used to implement a GPS antenna, and capacitor 131 can be placed at the second included angle. The range is thus used to realize a right-hand circularly polarized antenna.

[0112] Specifically, the first included angle (Inductor grounding method) and second included angle (Capacitor-to-Ground Method) The relationship with the antenna's circular polarization direction is shown in Table 1: Table 1 Based on the above and the periodicity of the circular polarization current distribution, the following characteristics of the circular polarization antenna design disclosed herein can be obtained: 1. Feature 1: at the first included angle α 0 Apply inductance at position L 0 Returning to the ground, the circular polarization effect is equivalent to the first included angle ( α 0 Apply inductance at a position of +180° L 0 Return to ground; at the second angle β 0 Apply capacitance at position C 0 Returning to the ground, the circular polarization effect is equivalent to the second included angle ( β 0 Apply a capacitor at a position of +180°. C 0 Return to the land.

[0113] Building on feature 1, we will continue to explore the effect of applying two inductors (or two capacitors) simultaneously on a circularly polarized antenna.

[0114] exist Figure 1 Based on the above, two first grounding terminals 120 are used for grounding, and both first grounding terminals 120 are connected to the grounding module of the device motherboard 100 through an inductor 121. One of the inductors has a value of 2L0 The inductor is located at the first included angle α 0 Location, another inductance value 2L 0 The inductor is set at the first included angle ( α 0 +180°) position. Based on the above, it can be seen that the circular polarization directions generated by the two inductors are the same, and the two inductors are connected in parallel. According to the characteristics of parallel inductors, we can obtain: (1) In equation (1), L This represents the inductance value of the equivalent inductance. As can be seen from the formula, the two values ​​are respectively set at... α 0 and( α 0 (+180°) position 2L 0 The inductance produces a circular polarization effect equivalent to that in a 0 (or α 0 Set at +180°) L 0 The inductance.

[0115] exist Figure 1 Based on the above, two second grounding terminals 130 are used for grounding, and both second grounding terminals 130 are connected to the grounding module of the device motherboard 100 through a capacitor 131. One of the capacitors has a value of 0.5. C 0 The capacitor is located at the second included angle. β 0 The location has another capacitance value of 0.5. C 0 The capacitor is located at the second included angle ( β 0 +180°) position. Based on the above, it can be seen that the two capacitors produce the same circular polarization direction, and the two capacitors are connected in parallel. According to the characteristics of parallel capacitors, we can obtain: (2) In equation (2), C represents the capacitance value of the equivalent capacitance. As can be seen from the formula, the two capacitors located at... β 0 and( β 0 0.5 at the +180° position C 0 The capacitor produces a circular polarization effect equivalent to that in β 0 (or β 0Set at +180°) C 0 The capacitor.

[0116] Based on this, we can derive the following characteristic 2 from characteristic 1. Feature 2: at the first included angle a 0 (or α 0 Set at +180°) L 0 The inductance produces a circular polarization effect equivalent to that of the inductance at the same point. α 0 and( α 0 Apply at +180° position 2L 0 The inductance; at the second included angle β 0 (or β 0 Set at +180°) C 0 The capacitor produces a circular polarization effect equivalent to that of the capacitors in the capacitors. β 0 and( β 0 Apply 0.5 at a position of +180°. C 0 The capacitor.

[0117] Based on the above feature 2, we can design an equivalent circularly polarized antenna using two capacitors or two inductors, thus providing more antenna design options.

[0118] Building upon characteristic 2 above, we further explore the influence of inductance (or capacitance) value and inductor (or capacitor) position on circularly polarized antennas. Based on this, we can calculate the influence of the positional distribution of multiple inductors (or capacitors) with different inductance (or capacitance) values ​​on the circular polarization of the antenna.

[0119] Axial ratio is an important parameter characterizing the performance of a circularly polarized antenna. It refers to the ratio of two orthogonal electric field components of a circularly polarized wave. A smaller axial ratio indicates better circular polarization performance, while a larger axial ratio indicates worse performance. In the embodiments of this disclosure, a criterion for evaluating the performance of a circularly polarized antenna is that the axial ratio should be less than 3 dB.

[0120] For the ring radiator 200, by applying different inductors or capacitors at a certain angular position and adjusting the values ​​of the inductors or capacitors, the optimal circular polarization axial ratio at that position can be obtained, and this optimal axial ratio corresponds to the optimal frequency of the antenna.

[0121] In one example, the original resonant frequency of the radiator 200 without the application of inductance and capacitance is 1.69 GHz. Figure 5 It is shown that when at the second included angle β=45° The axial ratio changes of the antenna when capacitances of 0.2pF, 0.3pF, and 0.4pF are applied at the specified locations. From... Figure 5 As can be seen, when the capacitance value is 0.3pF, the axial ratio of the antenna circular polarization reaches its optimum at a frequency of 1.63GHz. At this time, the capacitance value of 0.3pF can be defined as the optimum capacitance value under this second angle, and the frequency of 1.63GHz corresponding to the optimum axial ratio can be defined as the optimum frequency under this second angle.

[0122] Based on the above examples, the optimal frequency (GHz) and optimal capacitance (pF) of the capacitor at different angles can be obtained respectively. Table 2 provides some examples. Table 2 As can be seen from Table 2, when the second included angle β The minimum required capacitance is at 45°, and it decreases with the second included angle. β As the value increases or decreases, the required optimal capacitance value also gradually increases, and the second included angle... β The larger the value, the lower the optimal frequency. Since the optimal frequency is the second included angle... β A function of capacitance, therefore defined (3) In equation (3), This indicates the capacitance value. Indicates the second included angle, therefore Indicates the capacitance value The capacitor at the second angle Capacitive pulling capability at different positions. The defined "capacitive pulling capability" refers to the ability of a capacitor to pull the current on the annular radiator 200 to rotate and form circular polarization after a capacitor is applied. It is precisely because of the existence of capacitive pulling capability that it is possible to achieve different second included angles. β By applying an appropriate capacitor, the antenna can be formed into a circularly polarized antenna with an axial ratio of less than 3dB. Furthermore, the greater the capacitive pulling force, the greater the shift of the antenna's optimal frequency towards lower frequencies.

[0123] It should be noted that, in this example, since the radiator 200 is annular, the second included angle... It is always proportional to its corresponding arc length, therefore the second included angle can be used. The position of the capacitor is indicated by the angle. In radiators of other shapes, the second included angle should be used. The location of the capacitor is represented by the corresponding arc length of the radiating body, that is, in equation (2) It should be expressed using the arc length of the radiating body between the capacitor and the feed point.

[0124] Furthermore, based on the aforementioned characteristic 1, it can be seen that when the same capacitor is applied to... and( β 0 The +180° position is equivalent, therefore in equation (3), It should be located between 0° and 180°. In cases where the angle is greater than 180°, it should be made Subtract 180° to bring it within the range of 0° to 180°. Similarly, in the case of a non-circular radiator, the length of the radiator should also be... The corresponding radiator arc length.

[0125] Furthermore, as mentioned above, the second included angle The directions of circular polarization are opposite in the ranges of 0°~90° and 90°~180°. To facilitate understanding and avoid interference between multiple capacitors in different circular polarization direction ranges, the second included angle is first defined below. It falls within the 0°~90° range, meaning that multiple capacitors all exhibit right-hand circular polarization.

[0126] After defining the capacitive pulling capacity, and considering characteristic 2 above, according to the principle of capacitor parallel connection, it can be seen that: the capacitive pulling capacity of one capacitor can be divided into two or more different capacitive pulling capacity components, that is, in the second included angle... Apply capacitance at position This can be equivalent to: at the second included angle Apply capacitance at position At the second angle Apply capacitance at position At the second angle Apply capacitance at position ... To demonstrate the above conclusion, let's look at an example. Figure 6 The figure shows the curves of the axial ratio variation of the circularly polarized antenna under the following four conditions: Case 1: Second included angle β 0 =45°, capacitance C 0 =0.3pF; Case 2: Second included angle β 1 =30°, capacitance C 1 =0.13pF; Case 3: Second included angle β 2 =50°, capacitance C2 =0.19pF; Case 4: Combine Case 2 and Case 3.

[0127] like Figure 6 It can be seen that when the capacitors in cases 2 and 3 are applied individually, their axial ratios differ significantly from those in case 1. However, when the capacitors in cases 2 and 3 are applied simultaneously, i.e., in case 4, the axial ratio and optimal frequency are very close to those in case 1.

[0128] Figure 6 This also proves that applying a capacitor at a certain location is equivalent to applying multiple capacitors of different capacitance values ​​to different locations. In fact, the sum of the pulling forces of these multiple capacitors is roughly equivalent to the pulling force of an equivalent single capacitor. Based on this experience, the following formula can be obtained: (4) Formula (4) will be strictly equal under characteristic 1, that is, the two capacitors are respectively set at... β 0 and( β 0 At the +180° position. As mentioned above, the two positions in characteristic 1 are completely equivalent, and the optimal frequency is exactly the same when the same capacitance is applied at the two special positions. However, when multiple capacitances are applied at other different positions, the two ends of formula (4) are only a very approximate relationship, which can also guide the calculation of multiple capacitance cases relatively accurately.

[0129] For example, given the parameters in cases 1 and 2 above, and with the angle in case 3 fixed, the capacitance value in case 3 can be calculated using formula (4). C 2 =0.192pF, very close to the capacitor used in case 4. C 2 =0.19pF. This also proves that the above formula (4) can be used to guide the design of antennas with multiple capacitors to achieve circular polarization. Formula (4) can help us quickly determine and select the corresponding capacitor positions and capacitance values.

[0130] It is worth noting that, in this embodiment, by describing the scheme for multiple capacitors, more design forms of circularly polarized antennas can be provided on the one hand, and electrostatic protection of the antenna structure can be achieved on the other hand. A brief explanation follows.

[0131] TVS (Transient Voltage Suppressor) is an electrostatic discharge (ESD) protection device. When the two terminals of a TVS diode are subjected to a reverse transient high-energy impact, it can change the high impedance between its two terminals to a low impedance, effectively protecting the precision components in electronic circuits.

[0132] A TVS diode is a device with a certain capacitance value, meaning it has a certain parasitic capacitance. At the antenna frequency involved in this disclosure, a TVS diode can be equivalent to a capacitor with a capacitance value of 0.13pF. Therefore, in the antenna structure of this disclosure, one or more TVS diodes can be used as one or more second ground terminals, that is, one TVS diode can be used as one of the capacitors (or a 0.13pF capacitor can be regarded as a TVS diode). For example, the capacitor in the aforementioned case 2 can be regarded as a TVS diode. With the capacitance value and position of the TVS diode fixed, the position and capacitance value of one or more other capacitors can be quickly calculated according to the above formula (4). Based on the realization of a circularly polarized antenna, the antenna can also be effectively protected against electrostatic discharge (ESD), and multiple TVS diodes can be used to achieve better ESD protection.

[0133] It is worth noting that, in order to keep the direction of the circularly polarized antenna unchanged, the aforementioned multiple capacitors should be located within the same circular polarization direction. For example, in the case of achieving right-hand circular polarization, the second included angle of the multiple capacitors... β They should all be within the ranges of 0°~90° and 180°~270°. Of course, when using formula (4) for calculation, the second included angle also needs to be included. β The conversion to the 0°~180° range has already been explained above and will be understood by those skilled in the art, so it will not be repeated here.

[0134] The above has explained the principle and structure of antennas with multiple capacitors. Based on this, according to the principle of parallel inductance, it can be seen that an inductor at a certain location can also be equivalent to multiple inductors at different locations and with different inductance values ​​connected in parallel.

[0135] In one example, the original resonant frequency of the radiator 200 without the application of inductance and capacitance is 1.69 GHz. Figure 7 It is shown that when in the first included angle α The axial ratio change curves of the antenna when inductances of 11nH, 13nH, and 15nH are applied at a 45° position. From... Figure 7 As can be seen, when the inductance value is 13nH, the axial ratio of the antenna circular polarization reaches its optimal value at a frequency of 1.745GHz. At this time, the inductance value of 13nH can be defined as the optimal inductance under the first angle, and the frequency of 1.745GHz corresponding to the optimal axial ratio can be defined as the optimal frequency under the second angle.

[0136] Based on the above examples, the optimal frequency (GHz) and optimal inductance (nH) of the inductor at different angles can be obtained respectively. Table 3 provides some examples. Table 3 As can be seen from Table 3, when the first included angle α The optimal inductance is greatest at 45°, and increases with the first included angle. α As the angle gradually increases or decreases, the required optimal inductance will also gradually decrease. Furthermore, the first included angle... α The larger the value, the higher the optimal frequency. Since the optimal frequency is the first included angle... α And a function of inductance, therefore defined (5) In equation (5), The inductance value represents the inductance of an inductor. Indicates the first included angle, therefore Indicates the inductance value The inductance at the first angle The inductive pulling capability at different positions. The defined "inductive pulling capability" refers to the ability of the inductive pull on the annular radiator 200 to rotate and form circular polarization after an inductance is applied. It is precisely because of the existence of the inductive pulling capability that it is possible to rotate at different first included angles. α By applying an appropriate inductance, the antenna can be formed into a circularly polarized antenna with an axial ratio of less than 3dB. Furthermore, the greater the inductance pulling force, the greater the shift of the antenna's optimal frequency towards higher frequencies.

[0137] It should be noted that, in this example, since the radiator 200 is annular, the first included angle... It is always proportional to its corresponding arc length, therefore the first included angle can be used. The position of the inductor is indicated by the angle. In radiators of other shapes, the first included angle should be used. The position of the inductor is represented by the corresponding arc length of the radiating body, that is, in equation (5) It should be expressed using the arc length of the radiating body between the inductor and the feed point.

[0138] Furthermore, based on the aforementioned characteristic 1, it can be seen that when the same inductor is applied to... and( The +180° position is equivalent, therefore in equation (5), It should be located between 0° and 180°. In cases where the angle is greater than 180°, it should be made Subtract 180° to bring it within the range of 0° to 180°. Similarly, in the case of a non-circular radiator, the length of the radiator should also be... The corresponding radiator arc length.

[0139] Furthermore, as can be seen from the foregoing, the first included angle The directions of circular polarization are opposite in the ranges of 0°~90° and 90°~180°. To facilitate understanding and avoid interference between multiple capacitors in different circular polarization direction ranges, the first included angle is defined below. It falls within the 0°~90° range, meaning that multiple inductors produce right-hand circular polarization.

[0140] After defining inductor traction capability, and considering characteristic 2 above, according to the principle of inductor parallel connection, it can be seen that: an inductor traction capability can be divided into two or more different inductor traction capability components, that is, in the first included angle... Apply capacitance at position This can be equivalent to: at the first included angle Apply inductance at position At the first angle Apply inductance at position At the first angle Apply inductance at position ...Combining the principle of parallel inductance in formula (1), the following empirical formula can be obtained: (6) Formula (6) will be strictly equal under characteristic 1, that is, the two inductors are respectively set at... and( At the +180° position, as mentioned above, the two positions in characteristic 1 are completely equivalent, and the optimal frequency is exactly the same when the same inductor is applied to the two special positions. However, when multiple inductors are applied to other different positions, the two ends of formula (6) are only a very approximate relationship, which can still guide the calculation of multiple inductor cases quite accurately. With the guidance of formula (6), more circularly polarized antenna design forms can be realized.

[0141] Through the detailed explanation of the design schemes for multiple capacitors and multiple inductors described above, the following characteristic 3 of the antenna structure of this disclosure can be obtained. Feature 3: Applying multiple inductors with different positions and inductance values ​​within the same circular polarization direction is equivalent to applying one inductor at a fixed position for circular polarization; applying multiple capacitors with different positions and capacitance values ​​within the same circular polarization direction is equivalent to applying one capacitor at a fixed position for circular polarization.

[0142] Based on feature 3, when designing a multi-inductor or multi-capacitor antenna, one can first use an inductor or capacitor to adjust to the optimal value at a certain angle, and then obtain the optimal values ​​and positions of the equivalent multiple inductors or capacitors according to the above formula (4) or (6).

[0143] It is worth noting that, by observing the optimal frequencies in Tables 2 and 3, it can be seen that for a radiator with an original resonant frequency of 1.69 GHz, when an inductor is applied back to ground, the optimal frequencies corresponding to the optimal axial ratio are all higher than the original resonant frequency of 1.69 GHz; while when a capacitor is applied back to ground, the optimal frequencies corresponding to the optimal axial ratio are all lower than the original resonant frequency of 1.69 GHz. This also proves the correctness of the aforementioned conclusion: using an inductor back to ground can reduce the effective electrical length of the antenna, while using a capacitor back to ground can increase the effective electrical length of the antenna.

[0144] As explained above, circular polarization can be achieved using either inductors or capacitors, and applying inductors or capacitors at appropriate locations can achieve left-hand or right-hand circular polarization. The explanation further discusses the superposition of the inductive pulling power of multiple inductors and the capacitive pulling power of multiple capacitors located within the same circular polarization direction range. The following section explains the influence of inductors or capacitors in different circular polarization direction ranges on circular polarization.

[0145] First, as mentioned earlier, the effect of an inductor or capacitor returning to ground to generate a circularly polarized antenna is defined as the "traction capability" of the capacitor or inductor. Based on this, the traction capability generated when the inductor or capacitor is in the right-hand circular polarization range is defined as "right-hand traction capability", and the traction capability generated when the inductor or capacitor is in the left-hand circular polarization range is defined as "left-hand traction capability".

[0146] Based on the principle of circular polarization, the following conclusions can be drawn: when multiple inductors or capacitors are placed in different left-handed or right-handed circular polarization intervals, as long as the right-handed pulling force of multiple inductors or capacitors is greater than the left-handed pulling force, the circular polarization direction of the antenna is right-handed; conversely, as long as the left-handed pulling force of multiple inductors or capacitors is greater than the right-handed pulling force, the circular polarization direction of the antenna is left-handed.

[0147] To demonstrate this conclusion, in one example, an inductor is placed in the right-hand circular polarization region of the antenna structure, and a capacitor is placed in the left-hand circular polarization region. Specifically, the inductor L is positioned at the first included angle. a =60° position; capacitor C is set at the second angle. β =-15° (i.e. β =345°) and C=0.13pF. As mentioned above, a capacitor C with a capacitance of 0.13pF can be equivalent to a TVS diode, thus providing electrostatic protection for the antenna structure, which will not be elaborated further.

[0148] first, Figure 8 This shows that when the inductor L is fixed at the first included angle a At a position of 60°, and with capacitor C = 0.13pF placed at the second included angle. β The curves showing the changes in antenna axial ratio and frequency with inductance value at -15°. Figure 8 As can be seen, the axial ratio of circular polarization reaches its optimum when the inductance L = 9nH, and the optimal frequency corresponding to this optimum axial ratio is 1.8GHz. However, comparing with Table 3 above, at the same angle ( α=60° The optimal frequency for applying an inductor back to ground alone is 1.785 GHz. This demonstrates that when both an inductor and capacitor are applied simultaneously, the pulling power of the capacitor will affect the pulling power of the inductor to a certain extent. This can be used to adjust the antenna resonant frequency during antenna design, increasing the adaptability and flexibility of the antenna design.

[0149] Figure 9 The radiation gain diagram of the antenna structure in this example is shown. Figure 9 It can be seen that the antenna structure is still right-hand circularly polarized. This is because the right-hand pulling force generated by the inductor is greater than the left-hand pulling force generated by the capacitor. Therefore, the antenna remains a right-hand circularly polarized antenna after the two are combined. This also proves the correctness of the above conclusion.

[0150] Based on the above discussion, the following characteristics of the circularly polarized antenna of this disclosure can be obtained: Feature 4: Multiple capacitors and multiple inductors can be placed at different locations on the antenna simultaneously. When the capacitors and inductors are both located in the same circular polarization range, their circular polarization effect is enhanced by superposition. When the capacitors and inductors are placed in circular polarization ranges in different directions, their circular polarization direction depends on the one with stronger pulling ability. For example, if the right-hand circular polarization pulling ability is greater than the left-hand circular polarization pulling ability, then the antenna structure will maintain right-hand circular polarization.

[0151] Based on the above four characteristics, those skilled in the art can undoubtedly achieve more flexible and applicable antenna structure design schemes. For example, by using combinations of inductors and / or capacitors with different pulling capabilities to ground, the optimal resonance can be adjusted while maintaining the circular polarization direction of the antenna; another example is that by using a distributed combination of capacitors and inductors to ground, a TVS diode can be applied to the antenna to achieve electrostatic protection of the antenna structure; and so on.

[0152] The principle and structure of the circularly polarized antenna structure disclosed above have been explained. This circularly polarized antenna can realize any suitable antenna type, such as a satellite positioning antenna, Bluetooth antenna, Wi-Fi antenna, and 4G / 5G antenna, etc., and this disclosure does not impose any limitations on it. Below, taking the implementation of a satellite positioning GPS antenna in a smartwatch using the above antenna structure as an example, a detailed description of the wearable device and GPS antenna according to the embodiments of this disclosure will be provided.

[0153] like Figure 10 As shown, in this embodiment, the smartwatch includes a housing, which comprises a mid-frame 310 and a bottom shell 320. Both the mid-frame 310 and the bottom shell 320 are made of non-metallic materials, such as plastic, ceramic, or silicone. In this embodiment, the watch body is circular, thus the housing forms a cylindrical outer shell structure. It is understood that the housing can also be any other suitable shape, and this disclosure does not limit this. It should be noted that although the bottom shell 320 is made of a non-metallic material in this embodiment, in fact, a right-handed circularly polarized GPS antenna as required by this disclosure can also be achieved when the bottom shell 320 is made of a metallic material; this disclosure does not limit this.

[0154] The motherboard 100 and battery 400 are located inside the casing. The battery 400 can be a lithium battery to power the motherboard 100. The motherboard 100 is the main PCB board of the device, which integrates the processor and various circuit modules, etc., which will not be described in detail in this disclosure.

[0155] It is worth noting that the motherboard 100 is equipped with a shielding cover 190, which is used to electromagnetically shield the processor and other circuit modules on the motherboard 100, thereby avoiding any impact on the antenna performance and improving the stability of the antenna performance.

[0156] A circular metal bezel 200 is disposed on the end face of the middle frame 310 away from the bottom case 320, that is, the metal bezel 200 is fixed to the edge of the front of the watch. The metal bezel 200 can serve as a metal decoration, enhancing the watch's texture and aesthetics, and can also be used to mount the screen assembly 500, that is, the screen assembly 500 is fixedly mounted on the metal bezel 200. More importantly, in this embodiment, the metal bezel 200 is positioned above the motherboard 100 as the radiator of the GPS antenna of this disclosure, that is... Figure 1 The radiator in the middle is 200.

[0157] In this embodiment, one end of the power supply terminal 110 is formed on the metal frame 200, and the other end is connected to the power supply module of the motherboard 100. Simultaneously, a first grounding terminal 120 and a second grounding terminal 130 are also formed on the metal frame 200. The first grounding terminal 120 is connected to the ground of the motherboard 100 through an inductor, and the second grounding terminal 130 is connected to the ground of the motherboard 100 through a capacitor. The implementation of the first grounding terminal 120 and the second grounding terminal 130 is readily apparent to those skilled in the art and will not be repeated here.

[0158] The assembled structure of the smartwatch in this embodiment is as follows: Figure 11 As shown. Since this embodiment mainly focuses on describing the GPS antenna structure, the smartwatch structure of this embodiment is simplified. The simplified GPS antenna structure is as follows. Figure 12 As shown.

[0159] like Figure 12 As shown, in the design of this embodiment of the GPS antenna, when it is not grounded through the first grounding terminal 120 and the second grounding terminal 130, the original resonant frequency of the antenna is about 1.46GHz, which is less than the operating frequency of the GPS antenna, 1.575GHz. Based on the aforementioned principle, it is known that an inductor-based method is needed to improve the resonant frequency of the antenna.

[0160] In this embodiment, the capacitor of the second grounding terminal 130 is a 0.13pF capacitor, which, as described above, can be equivalent to a TVS diode, thereby achieving electrostatic protection for the antenna. Of course, those skilled in the art will understand that a TVS diode can also be used as the second grounding terminal 130 in this embodiment; the essence is the same. The second grounding terminal 130 is located at the second included angle. β =15° position.

[0161] After determining the capacitance value and location, the location and value of the inductor can be determined based on the goal of achieving "right-hand circular polarization of the GPS antenna with an optimal frequency of 1.575 GHz". Specifically, a suitable inductor value and location can be obtained according to the relationship between the optimal frequency and the inductance value and the first angle in Table 3. In this embodiment, after optimization, an inductance value of 11 nH is applied at the first angle. α When the inductance is 65°, the right-hand circular polarization required for a GPS antenna can be achieved. That is, in this embodiment, when the inductance parameters are: α =65°, inductance value is 11nH; and capacitor parameters are... β The right-hand circularly polarized GPS antenna of a smartwatch performs best when the angle is 15° and the capacitance is 0.13pF.

[0162] Figure 13 The curve showing the change in axial ratio of the GPS antenna in this embodiment as a function of frequency is illustrated. Figure 14 The curve showing the return loss of the GPS antenna in this embodiment as a function of frequency is illustrated. Figure 15 The curve showing the antenna efficiency of the GPS antenna in this embodiment as a function of frequency is illustrated. Figures 13 to 15 It can be seen that the antenna has good axial ratio, antenna return loss and antenna efficiency in the frequency bands including GPS, Beidou and GLONASS (1560~1610 MHz, bandwidth of 50MHz), which also proves that the circularly polarized GPS antenna of this embodiment has good antenna performance and can meet the needs of smartwatches.

[0163] To further illustrate the wearing performance of the GPS antenna in this embodiment, Figure 16 The figure shows the total gain, right-hand circular polarization gain, and left-hand circular polarization gain of the antenna in this embodiment in the XOZ plane at a frequency of 1.575 GHz. θ The curve showing the change in angle. Figure 17 The diagram shows the total gain, right-hand circular polarization gain, and left-hand circular polarization gain of the antenna in this embodiment in the YOZ plane at a frequency of 1.575 GHz. θ The curve showing the change of angle. The XOZ plane and YOZ plane mentioned here represent... Figure 18 and Figure 19 In the context of wearing a watch, the spatial coordinate system plane is defined. Figure 16 and Figure 17 It can be seen that the gain of the right-hand circularly polarized wave and the total gain of the antenna are... θ The circularly polarized wave exhibits good consistency within an angle range of ±60°, and its left-hand circular polarization wave is well suppressed, which also proves that the circularly polarized wave of this embodiment has good right-hand circular polarization performance.

[0164] Figure 18 and Figure 19 The radiation patterns of the right-hand circularly polarized wave from this embodiment of the antenna in the XOZ and YOZ planes are shown at a frequency of 1.575 GHz. Figure 18 and Figure 19 As can be seen, the maximum gain of the GPS antenna in this embodiment occurs above the arm, which precisely meets the needs of the three main planes we need to focus on when the watch is worn on the arm: namely, the direction in which we look at the watch when we raise our wrist (the watch is pointing towards the sky), and the two directions in which the arm swings during running and walking, the 6 o'clock and 9 o'clock positions, both pointing towards the sky. Furthermore, through... Figure 18 and Figure 19It can also be seen that the radiation from the left and right antennas in the XOZ plane has good symmetry, which indicates that the GPS antenna of this embodiment has good consistency for left- and right-handed wearers. In other words, it can simultaneously meet the needs of users who wear watches on both their left and right hands. The above results show that the right-hand circularly polarized GPS antenna of this embodiment has good antenna performance and can meet the requirements of rapid satellite acquisition and accurate navigation.

[0165] exist Figure 10 In the illustrated embodiment, the original resonant frequency of the antenna structure without the application of capacitors and inductors is 1.46 GHz, lower than the 1.575 GHz of the GPS antenna. Therefore, a right-hand circularly polarized GPS antenna is implemented using inductance as the primary traction capability. Figure 10 If, without changing other environmental factors (such as the material of the plastic casing), only the radius of the metal bezel 200 is reduced by 2.5mm (and of course, the screen and motherboard must also be reduced accordingly), the original resonant frequency of the watch's metal bezel will become approximately 1.69GHz, which is greater than the 1.575GHz of the GPS antenna. In this case, according to the principles described above, a capacitor-driven grounding method is required to implement the right-hand circularly polarized GPS antenna.

[0166] To further illustrate, Figure 20 The document illustrates an implementation of a right-hand circularly polarized GPS antenna using a capacitor ground loop.

[0167] like Figure 20 As shown, in this embodiment, the smartwatch includes a housing, which comprises a mid-frame 310 and a bottom shell 320. Specifically, in this embodiment, both the mid-frame 310 and the bottom shell 320 are made of metal. The metal mid-frame and bottom shell offer a better texture, improving the device's aesthetics and enhancing its competitiveness. Of course, when the bottom shell 320 is made of a non-metallic material (e.g., plastic, ceramic, silicone, etc.), the right-hand circularly polarized GPS antenna can still be implemented according to the scheme proposed in this disclosure, as those skilled in the art will understand.

[0168] The motherboard 100 and battery 400 are located inside the housing. The battery 400 can be a lithium battery to power the motherboard 100. The motherboard 100 is the main PCB board of the device, which integrates the processor and various circuit modules. The shielding cover 190 provides electromagnetic shielding for the various circuit modules on the motherboard 100, which will not be described in detail here. The ground of the motherboard 100 is connected to the metal frame 310. For example, the ground of the motherboard 100 is connected to the frame 310 through four connection terminals. Since the frame 310 is connected to the ground of the motherboard 100, the frame 310 is equivalent to the ground of the motherboard 100.

[0169] The metal bezel 200 is fixed to the end face of the middle frame 310 away from the bottom case 320, that is, the metal bezel 200 is fixed to the edge of the front of the watch. The metal bezel 200 can serve as a metal decoration to enhance the texture and aesthetics of the watch, and it can also be used to mount the screen assembly 500, that is, the screen assembly 500 is fixedly mounted on the metal bezel 200. More importantly, in this embodiment, the metal bezel 200 serves as the radiator of the GPS antenna of this disclosure, that is... Figure 1 The radiator in the middle is 200.

[0170] It should be noted that in this embodiment, an insulating layer 600 is provided between the metal frame 200 and the middle frame 310. The purpose of the insulating layer 600 is to form a gap structure by insulating and isolating the metal frame 200 from the ground of the motherboard 100, thereby enabling the antenna function by feeding power to the formed gap structure. In other words, in Figure 10 In one embodiment, the antenna's slot structure is formed through the slot between the main board 100 and the metal frame 200. However, in this embodiment, the antenna's slot structure is formed through the slot (i.e., the insulating layer 600) between the metal middle frame 310 and the metal frame 200. These different antenna structures demonstrate that the inventive concept of this disclosure can be applied to various antenna structures, all of which can achieve the design requirements of circular polarization, thus providing more options for antenna design in watches.

[0171] In this embodiment, the assembly structure of the smartwatch is as follows: Figure 21 As shown, the power supply terminal 110 is connected across the gap formed by the metal front frame 200 and the metal middle frame 310, and the power supply terminal 110 is connected to the power supply module of the motherboard 100. Additionally, the GPS antenna structure of this embodiment also includes two second grounding terminals 130, which are connected to ground via two capacitors.

[0172] In this embodiment, without applying two capacitors, the original resonant frequency of the metal frame 200 is around 1.69 GHz, which is greater than the operating frequency of the GPS antenna, 1.575 GHz. Therefore, the resonant frequency of the antenna is reduced by using capacitors to return to ground.

[0173] First, to provide electrostatic protection for the antenna structure, a capacitor with a capacitance of 0.13pF is placed at the second angle. β The 190° position can be equivalent to a TVS diode, thereby achieving electrostatic protection for the antenna. Of course, those skilled in the art will understand that in this embodiment, a TVS diode can also be used as one of the second grounding terminals 130, which is essentially the same.

[0174] After determining the capacitance and location of one capacitor, the location and capacitance of the other capacitor can be determined based on the goal of achieving "right-hand circular polarization of the GPS antenna with an optimal frequency of 1.575 GHz". In this embodiment, the capacitance of the other capacitor is optimized to 0.2 pF and it is located at the second included angle. β =50° position. As mentioned above, both capacitors are located within the right-hand circular polarization region, therefore the resulting antenna is also right-hand circular polarization.

[0175] Figure 22 The curve showing the change in axial ratio of the GPS antenna in this embodiment as a function of frequency is illustrated. Figure 23 The curve showing the return loss of the GPS antenna in this embodiment as a function of frequency is illustrated. Figure 24 The graph shows the radiation efficiency of the GPS antenna in this embodiment as a function of frequency. From... Figures 22 to 24 It can be seen that the GPS antenna in this embodiment has good axial ratio, antenna return loss and antenna efficiency.

[0176] To further illustrate that the GPS antenna of this embodiment has good wearability, Figure 25 The figure shows the total gain, right-hand circular polarization gain, and left-hand circular polarization gain of the antenna in this embodiment in the XOZ plane at a frequency of 1.575 GHz. θ The curve showing the change in angle. Figure 26 The diagram shows the total gain, right-hand circular polarization gain, and left-hand circular polarization gain of the antenna in this embodiment in the YOZ plane at a frequency of 1.575 GHz. θ The curve showing the change of angle. The XOZ plane and YOZ plane mentioned here represent... Figure 27 and Figure 28 In the context of wearing a watch, the spatial coordinate system plane is defined. Figure 25 and Figure 26 It can be seen that the gain of the right-hand circularly polarized wave and the total gain of the antenna are... θ The circularly polarized wave exhibits good consistency within an angle range of ±60°, and its left-hand circular polarization wave is well suppressed, which also proves that the circularly polarized wave of this embodiment has good right-hand circular polarization performance.

[0177] Figure 27 and Figure 28 The radiation patterns of the right-hand circularly polarized wave from this embodiment of the antenna in the XOZ and YOZ planes are shown at a frequency of 1.575 GHz. Figure 27 and Figure 28As can be seen, the maximum gain of the GPS antenna in this embodiment occurs above the arm, which precisely meets the needs of the three main planes we need to focus on when the watch is worn on the arm: namely, the direction in which we look at the watch when we raise our wrist (the watch is pointing towards the sky), and the two directions in which the arm swings during running and walking, the 6 o'clock and 9 o'clock positions, both pointing towards the sky. Furthermore, through... Figure 27 and Figure 28 It can also be seen that the radiation from the left and right antennas in the XOZ plane has good symmetry, which indicates that the GPS antenna of this embodiment has good consistency for left- and right-handed wearers. In other words, it can simultaneously meet the needs of users who wear watches on both their left and right hands. The above results show that the right-hand circularly polarized GPS antenna of this embodiment has good antenna performance and can meet the requirements of rapid satellite acquisition and accurate navigation.

[0178] Through the above description of the GPS right-hand circularly polarized antenna for smartwatches using the two specific embodiments, those skilled in the art will understand that the antenna structure of this disclosure directly feeds a ring radiator, utilizing inductors and / or capacitors to pull the current of the radiator, causing the ring radiator to generate an effective rotating ring current, thereby forming a circularly polarized wave and realizing a circularly polarized antenna. Compared to linearly polarized antennas, circularly polarized antennas have higher receiving efficiency, resulting in more accurate positioning during satellite positioning. Compared to known circularly polarized schemes, this disclosure eliminates the need for coupling with other structures, greatly simplifying the structure and complexity of the circularly polarized antenna, making it easier to implement in smaller smart wearable devices. Furthermore, through the above description of the location and quantity of capacitors and inductors, as well as the discussion of the influence of inductors and capacitors on the effective electrical length of the antenna, more antenna structure design forms can be provided to meet the applicability of antenna structures in various devices.

[0179] exist Figure 10 and Figure 20 The two embodiments illustrate two different antenna structures, as mentioned above, in which... Figure 10 In this implementation, the antenna gap is formed through the gap between the motherboard 100 and the metal frame 200, while... Figure 20 In this embodiment, the antenna gap is formed through the gap between the metal mid-frame 310 and the metal front frame 200. However, the antenna form used to implement this solution is not limited to this; for example… Figure 29 An alternative implementation is shown.

[0180] like Figure 29As shown, in this embodiment, the smartwatch includes a housing, which includes a mid-frame and a non-metallic bottom shell 320. The mid-frame includes a metal upper frame 311 and a non-metallic lower frame 312. In this embodiment, the antenna's slot structure is achieved through a slot 313 between the motherboard 100 and the metal upper frame 311. This solution is implemented by feeding power to the slot 313 and using an inductor and / or capacitor to return the signal to ground; that is, the upper frame 311 forms the main radiator of the antenna. Those skilled in the art, in conjunction with the foregoing, can understand and fully implement the solution of this embodiment, and further details are omitted.

[0181] In addition, Figure 29 Based on the implementation method, those skilled in the art will understand that the upper frame 311 and the lower frame 312 can also be replaced by a complete metal frame, the principle of which is the same, and this disclosure will not elaborate on this.

[0182] It is worth noting that, in this embodiment of the present disclosure, in order to achieve better excitation of circularly polarized waves on the annular radiator, the motherboard 100 should have a similar shape to the annular radiator, thereby forming a gap between them that is as uniform as possible. However, in practical applications, the motherboard 100 is generally difficult to guarantee a complete annular shape due to the influence of the internal stacking design of the device. For example... Figure 30 As shown, in order to avoid components such as batteries, the mainboard is partially removed to form an irregular shape. In this embodiment, in order to ensure better excitation of circularly polarized waves on the ring radiator, the supplementary part 101 is used to supplement the irregular edge of the mainboard 100, so that it has a shape similar to the radiator 200, thereby ensuring antenna performance.

[0183] In one example, taking a smartwatch as an example, the width of the edge supplementary portion 101 of the motherboard 100 only needs to be greater than 1.5mm. Furthermore, this supplementary portion 101 can be a structure integrally formed with the motherboard, or it can be replaced by a steel sheet used to fix the two ends of other components (such as speakers) and electrically connect them to the PCB board; that is, as long as the annular ground portion of the motherboard has a similar shape to the annular radiator, it is acceptable. Moreover, the annular ground portion of the motherboard and the annular radiator only need to be approximately similar in shape; minor concave defects on the periphery of the motherboard will not affect the performance of the antenna structure of this embodiment.

[0184] It's also worth noting that, taking smartwatches as an example, smartwatches generally include at least one satellite positioning antenna and one Bluetooth / Wi-Fi antenna. In this disclosed solution, in... Figure 12 Based on the implementation method, the Bluetooth / Wifi antenna disclosed herein can be designed in various ways. Since the center operating frequency of the Bluetooth antenna and the Wifi antenna is the same, which is approximately 2.45 GHz, for ease of description, it will be referred to as "Bluetooth antenna" below.

[0185] Option 1: Directly utilize the resonance of about 2.45 GHz generated by the higher-order resonance of the GPS antenna in the above embodiment as a Bluetooth antenna. This higher-order resonance is mostly a linearly polarized wave that can be used for Bluetooth antennas.

[0186] This situation involves GPS and Bluetooth sharing the same power supply. Although this solution is simple in structure, it requires the use of a splitter / splitter, which causes some loss to the antenna and has limited applicability.

[0187] Option 2: Design a separate Bluetooth antenna inside the watch, such as on a PCB board, and ensure that the Bluetooth antenna and GPS antenna are fed independently. In this case, the coupling between the Bluetooth antenna and the GPS antenna is weak and can be ignored.

[0188] Option 3: such as Figure 31 As shown, a Bluetooth antenna 700 is positioned between the motherboard 100 and the radiator 200. This Bluetooth antenna can be implemented using a monopole antenna or an IFA antenna. In the illustration, the Bluetooth antenna 700 uses a monopole antenna, with its radiating stub parallel to the radiator 200. At this point, there is a certain coupling effect between the Bluetooth antenna 700 and the radiator 200, which is equivalent to applying a fixed capacitor with a relatively small capacitance value between the motherboard 100 and the radiator 200. Therefore, this Bluetooth antenna, like the aforementioned capacitor effect, will have a certain impact on the circular polarization of the GPS antenna. Thus, the position of the Bluetooth antenna can be set according to the aforementioned principle, for example, placing the Bluetooth antenna in the right-hand circular polarization range. That is, according to the principle of capacitor splitting and inductor-capacitor combination proposed in this case, the implementation method of this Bluetooth antenna will not affect the implementation of the right-hand circular polarization GPS antenna.

[0189] The circularly polarized antenna structure of this disclosure directly feeds a ring radiator and utilizes inductors and / or capacitors to pull the current in the radiator, causing the ring radiator to generate an effective rotating ring current, thereby forming a circularly polarized wave and realizing a circularly polarized antenna. Compared to linearly polarized antennas, circularly polarized antennas have higher receiving efficiency, resulting in more accurate positioning during satellite positioning. Compared to known circularly polarized schemes, this disclosure eliminates the need for coupling with other structures, greatly simplifying the structure and reducing the complexity of the circularly polarized antenna, making it easier to implement in smaller smart wearable devices. Furthermore, through the above description of the location and quantity of capacitors and inductors, and the discussion of the influence of inductors and capacitors on the effective electrical length of the antenna, more antenna structure design forms can be provided to meet the applicability of the antenna structure to devices of various sizes.

[0190] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the embodiments. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom remain within the scope of protection created by this specification.

Claims

1. A circularly polarized antenna for a wearable device, characterized in that, include: An annular slit structure, the slit structure comprising an annular radiator; The motherboard includes a power supply module and a grounding module; A power supply terminal is connected across the slot structure, with one end of the power supply terminal directly connected to the annular radiator and the other end connected to the power supply module; as well as At least one first grounding terminal is connected across the slot structure, one end of the first grounding terminal is electrically connected to the annular radiator, and the other end is connected to the grounding module through an inductor assembly.

2. The circularly polarized antenna according to claim 1, characterized in that, The gap structure is formed by the gap between the motherboard and the annular radiator.

3. The circularly polarized antenna according to claim 1 or 2, characterized in that, The housing of the wearable device includes a bottom shell and a middle frame, at least a portion of which forms the annular radiator.

4. The circularly polarized antenna according to claim 1 or 2, characterized in that, The housing of the wearable device includes a mid-frame and a front frame, at least a portion of which forms the annular radiator.

5. The circularly polarized antenna according to claim 1, characterized in that, The housing of the wearable device includes a mid-frame and a front frame, and the gap between the mid-frame and the front frame forms the gap structure.

6. The circularly polarized antenna according to claim 5, characterized in that, An insulating layer is provided in the gap structure between the middle frame and the front frame.

7. The circularly polarized antenna according to claim 5 or 6, characterized in that, One end of the power supply terminal is connected to the front frame, and the other end is connected to the power supply module of the motherboard. One end of the at least one first grounding terminal is connected to the middle frame, and the other end is connected to the grounding module of the motherboard.

8. The circularly polarized antenna according to any one of claims 1 to 7, characterized in that, The effective length of the ring radiator is equal to the wavelength of the wireless signal transmitted and received by the circularly polarized antenna.

9. The circularly polarized antenna according to any one of claims 1 to 8, characterized in that, The gap structure is a closed ring structure with the ends connected.

10. The circularly polarized antenna according to any one of claims 1 to 9, characterized in that, In the case where the at least one first grounding terminal includes a plurality of first grounding terminals, the plurality of first grounding terminals are arranged circumferentially along the slot structure.

11. The circularly polarized antenna according to any one of claims 1 to 10, characterized in that, The inductor assembly is used to draw current onto the annular radiator, so that the annular radiator generates a rotating annular current.

12. The circularly polarized antenna according to any one of claims 1 to 11, characterized in that, The line connecting the power supply terminal and the center of the annular radiator is the first line, the line connecting the first grounding terminal and the center of the annular radiator is the second line, the clockwise rotation direction of the annular radiator is the first direction, and along the first direction, the first line and the second line form a first angle. ; in, The inductor assembly causes a right-handed current to be generated on the ring radiator; or, The inductor component causes a left-handed current to be generated on the annular radiator.

13. The circularly polarized antenna according to any one of claims 1 to 12, characterized in that, It also includes at least one second grounding terminal, which is connected across the slot structure. One end of the second grounding terminal is electrically connected to the annular radiator, and the other end is connected to the grounding module through a capacitor assembly.

14. The circularly polarized antenna according to claim 13, characterized in that, The capacitor assembly is used to draw current onto the annular radiator, so that the annular radiator generates a rotating annular current.

15. The circularly polarized antenna according to claim 13 or 14, characterized in that, The line connecting the power supply terminal to the center of the annular radiator is the first line, the line connecting the second grounding terminal to the center of the annular radiator is the third line, the counterclockwise rotation direction of the annular radiator is the second direction, and along the second direction, the first line and the third line form a second angle. β ; in, The capacitor assembly causes a right-handed current to be generated on the annular radiator; or, The capacitor assembly causes a left-handed current to be generated on the annular radiator.

16. The circularly polarized antenna according to any one of claims 13 to 15, characterized in that, The at least one first grounding terminal and the at least one second grounding terminal are arranged circumferentially along the slot structure.

17. The circularly polarized antenna according to any one of claims 13 to 16, characterized in that, In the case where the at least one second grounding terminal includes a plurality of second grounding terminals, the plurality of second grounding terminals are arranged circumferentially along the slot structure.

18. The circularly polarized antenna according to any one of claims 13 to 17, characterized in that, The polarization direction of the circularly polarized antenna depends on the superposition of the inductive pulling capability of the inductor component and the capacitive pulling capability of the capacitor component. The polarization directions of the circularly polarized antenna include: left-hand circular polarization and right-hand circular polarization. or, The inductive pulling capability of the inductor component and the polarization direction corresponding to the capacitive pulling capability of the capacitor component are the same, and the polarization direction of the circularly polarized antenna is the polarization direction corresponding to either the inductive pulling capability or the capacitive pulling capability. or, The inductive pulling capability of the inductor component corresponds to the opposite polarization direction to the capacitive pulling capability of the capacitor component, and the polarization direction of the circularly polarized antenna is the polarization direction corresponding to the larger of the inductive pulling capability and the capacitive pulling capability.

19. The circularly polarized antenna according to any one of claims 1 to 18, characterized in that, The wearable device's housing and display module form a receiving space, the motherboard is disposed within the receiving space, and at least a portion of the housing forms the annular radiator.

20. The circularly polarized antenna according to claim 1 or 2, characterized in that, The housing of the wearable device includes a face frame, a middle frame, and a bottom shell. The face frame is fixed to the end face of the middle frame away from the bottom shell. The face frame forms the gap structure with the motherboard. The face frame forms the annular radiator.

21. The circularly polarized antenna according to claim 1 or 2, characterized in that, The wearable device housing includes a bottom shell and a middle frame, the motherboard is disposed inside the housing, and the gap structure is formed between the motherboard and the middle frame, the middle frame forming the annular radiator.

22. The circularly polarized antenna according to claim 1, characterized in that, The wearable device housing includes a face frame, a middle frame, and a bottom shell. The middle frame is electrically connected to the grounding module of the motherboard. The face frame is fixed on the side end face of the middle frame away from the bottom shell. An insulating layer is provided between the middle frame and the face frame to form the gap structure between the middle frame and the face frame. The face frame forms the annular radiator.

23. A wearable device, characterized in that, Including the circularly polarized antenna according to any one of claims 1 to 22.

24. The wearable device according to claim 23, characterized in that, The wearable device is a wrist-worn device.

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