Circularly polarized antenna structure and smart wearable device

Abstract

The present disclosure relates to the technical field of electronic equipment, in particular to a circularly polarized antenna structure and a smart wearable device. The circularly polarized antenna structure is applied to the smart wearable device, comprising: a mainboard; a ring-shaped radiator, the effective circumference of which around a circle is equal to a wavelength of a center operating frequency of the antenna structure; a feed terminal, which is connected between the mainboard and the radiator, one end of which is electrically connected with the radiator, and the other end is connected with a feed module of the mainboard; and a grounding terminal, one end of which is electrically connected with the radiator, and the other end is electrically connected with a grounding module of the mainboard through a first capacitor. The antenna structure of the present disclosure can realize a circularly polarized antenna on the smart wearable device, improve the antenna receiving efficiency and the antenna performance of the device, and improve the positioning accuracy.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of electronic devices, and in particular to a circularly polarized antenna structure and a smart wearable device. BACKGROUND

[0002] With the development of smart wearable devices, satellite positioning function has become an indispensable function. Commonly used satellite positioning systems include Global Positioning System (GPS), Beidou Satellite Navigation System (BDS), and GLONASS.

[0003] In order to enhance the transmission efficiency of satellites to the ground (such as to enhance the penetration ability and coverage area, etc.), the satellite-to-ground transmitting antenna adopts a circularly polarized form. Similarly, in order to enhance the receiving ability of the positioning antenna, the receiving antenna of the device should also adopt the same circularly polarized antenna as the transmitting antenna. However, in the related art, the smart wearable device is limited by the volume or industrial design, and it is difficult to realize a circularly polarized antenna. Instead, a linearly polarized antenna is commonly used, which results in poor satellite positioning performance of the device and inaccurate capture of the motion trajectory. SUMMARY

[0004] To improve the satellite positioning accuracy of the smart wearable device, the present disclosure provides a circularly polarized antenna structure and a smart wearable device.

[0005] In a first aspect, the present disclosure provides a circularly polarized antenna structure applied to a smart wearable device, the antenna structure comprising:

[0006] a main board;

[0007] a ring-shaped radiator, the effective circumference of which around one turn is equal to one wavelength of the center operating frequency of the antenna structure;

[0008] a feeding terminal, which is connected between the main board and the radiator, one end of which is electrically connected to the radiator, and the other end of which is connected to a feeding module of the main board; and

[0009] a grounding terminal, one end of which is electrically connected to the radiator, and the other end of which is electrically connected to a grounding module of the main board through a first capacitor.

[0010] In some embodiments, a line connecting the feeding terminal and the center point of the radiator is a first line, and a line connecting the grounding terminal and the center point of the radiator is a second line; the counterclockwise direction of the radiator is a first direction, and along the first direction, the first line to the second line forms a first included angle β;

[0011] wherein, or,

[0012] In some embodiments, the first included angle β is 10° to 80°.

[0013] In some embodiments, the annular structure of the radiator is any one of the following:

[0014] Circular rings, rectangular rings, rhomboid rings, or polygonal rings.

[0015] In some embodiments, the antenna structure is any one of the following:

[0016] Satellite positioning antenna, Bluetooth antenna, WiFi antenna or 4G / 5G antenna.

[0017] In some embodiments, the capacitance of the first capacitor is 0.2pF to 1.5pF.

[0018] In a second aspect, embodiments of this disclosure provide a smart wearable device, including an antenna structure according to any embodiment of the first aspect.

[0019] In some embodiments, the smart wearable device is a smartwatch, and the smartwatch includes:

[0020] The housing, wherein the main board is disposed within the housing; and

[0021] A metal frame surrounds the edge of the open end of the housing, forming the radiator.

[0022] In some embodiments, the smartwatch further includes a screen assembly that is fitted to the open end of the housing via the metal bezel.

[0023] In some implementations, the smart wearable device is any one of the following:

[0024] Smart bracelets, smartwatches, smart earphones, or smart glasses.

[0025] The circularly polarized antenna structure provided in this disclosure is applied to smart wearable devices. The antenna structure includes a motherboard and a ring-shaped radiator. The effective circumference of the radiator is equal to one wavelength of the operating frequency at the center of the antenna structure. A feed terminal and a ground terminal are connected between the motherboard and the radiator. One end of the ground terminal is electrically connected to the radiator, and the other end is connected to the grounding template of the motherboard through a first capacitor. The first capacitor pulls current into the radiator, causing the ring-shaped radiator to generate an effective rotating ring current, thereby forming a circularly polarized wave and realizing a circularly polarized antenna. Compared with linearly polarized antennas, circularly polarized antennas have higher receiving efficiency, resulting in more accurate positioning when performing satellite positioning functions. Furthermore, by directly feeding the radiator to form the circularly polarized antenna structure, there is no need to couple other structures, which greatly simplifies the structure and reduces the cost of the circularly polarized antenna, making it easier to implement in smaller smart wearable devices.

[0026] 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, and a second connection line between the ground terminal and the center point of the radiator. The counterclockwise angle between the first and second connections is a first angle. By adjusting the size of the first angle, i.e., changing the position of the first capacitor, circularly polarized antennas in different directions can be achieved. When the first angle is 0° to 90° or 180° to 270°, the current in the radiator rotates counterclockwise, thus forming a right-hand circularly polarized antenna; when the first angle is 90° to 180° or 270° to 360°, the current in the radiator rotates clockwise, thus forming a left-hand circularly polarized antenna. This antenna structure, by adjusting the first angle, can achieve circularly polarized waves in different directions, meeting the design requirements of circularly polarized antennas in different directions.

[0027] The circularly polarized antenna structure provided in this embodiment has a first included angle within the range of 0° to 90° to form a right-hand circularly polarized wave. Since the transmitting antenna for satellite positioning uses a right-hand circularly polarized wave, a right-hand circularly polarized antenna structure is also used for receiving, improving antenna efficiency and positioning accuracy. The first included angle is further optimized to 10° to 80°, so that the position of the first capacitor is far away from the current zero point (i.e., 0°) or current peak point (i.e., 90°) of the two orthogonal components of the circularly polarized wave, in order to maintain the independence of the two orthogonal component waves, thereby improving the radiation efficiency of the circularly polarized antenna and improving antenna performance.

[0028] The smart wearable device provided in this disclosure includes the circularly polarized antenna structure described in the above embodiments, and therefore has all the aforementioned beneficial effects. Furthermore, when the smart wearable device is a smartwatch, the metal frame or mid-frame on the smartwatch forms the radiator. On one hand, the metal frame or mid-frame can serve as a decorative structure for the watch, improving its aesthetics; on the other hand, using the metal frame or mid-frame as the radiator reduces the space occupied by the antenna structure inside the watch, and a larger radiator also significantly enhances the antenna's radiation performance. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a structural schematic diagram of a circularly polarized antenna structure according to some embodiments of this disclosure.

[0031] Figure 2 This is an exploded view of the structure of a smartwatch according to one embodiment of the present disclosure.

[0032] Figure 3 This is a cross-sectional view of a smartwatch according to one embodiment of the present disclosure.

[0033] Figure 4 This is a current distribution variation diagram of a circularly polarized antenna according to one embodiment of the present disclosure.

[0034] Figure 5 This is a schematic diagram of the structure of a circularly polarized antenna according to one embodiment of the present disclosure.

[0035] Figure 6 This is a return loss curve of a circularly polarized antenna according to one embodiment of the present disclosure.

[0036] Figure 7 This is an antenna efficiency curve of a circularly polarized antenna according to one embodiment of the present disclosure.

[0037] Figure 8 This is an axial ratio curve of a circularly polarized antenna according to one embodiment of the present disclosure.

[0038] Figure 9 This is a gain curve of a circularly polarized antenna according to one embodiment of the present disclosure.

[0039] Figure 10 This is a radiation pattern of a circularly polarized antenna in the xoz plane according to one embodiment of this disclosure.

[0040] Figure 11 This is a radiation pattern of a circularly polarized antenna on a yoz screen according to one embodiment of the present disclosure.

[0041] Figure 12 This is a gain curve of a circularly polarized antenna in the xoz plane according to one embodiment of the present disclosure.

[0042] Figure 13 This is a gain curve of a circularly polarized antenna in the yoz plane according to one embodiment of the present disclosure.

[0043] Figure 14 This is a cross-sectional view of a smartwatch according to another embodiment of this disclosure.

[0044] Explanation of reference numerals in the attached figures:

[0045] 100-Main board; 110-Power supply terminal; 111-Power supply point; 120-Grounding terminal; 121-First capacitor; 130-Spring; 200-Radiator; 201-Metal frame; 310-Bezel; 320-Bottom shell; 400-Battery; 500-Screen assembly. Detailed Implementation

[0046] The technical solutions of this disclosure will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without inventive effort are within the scope of protection of this disclosure. Furthermore, the technical features involved in the different embodiments of this disclosure described below can be combined with each other as long as they do not conflict with each other.

[0047] Circularly polarized antennas are widely used in satellite navigation systems because the circularly polarized waves they generate can be received by linearly polarized antennas of any direction, and they can also receive incoming waves of any linear polarization, exhibiting excellent antenna performance. Therefore, circularly polarized antennas are commonly used in satellite positioning or reconnaissance jamming. Circularly polarized antennas are further divided into left-hand circularly polarized antennas and right-hand circularly polarized antennas. 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 circularly polarized antennas.

[0048] 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.

[0049] To address the aforementioned issues, some smartwatches employ circularly polarized antennas for satellite positioning. This approach involves feeding an inverted-F antenna (IFA) beneath a metal ring on the watch's upper surface, and coupling it to the metal ring via a parasitic antenna element (the grounded branch of the IFA). In this circularly polarized design, specific length requirements apply to the IFA antenna and parasitic element to generate a loop current on the metal ring: the IFA and / or parasitic element lengths must be approximately (1 / 4) the arc length of the metal ring to achieve an effective loop current. This "effective loop current" refers to a loop current that can circulate relatively evenly along the metal ring with phase changes, thus providing current for the circularly polarized antenna. Furthermore, because the loop current on the metal ring is achieved through coupling between the IFA antenna element, the parasitic element, and the metal ring, the design requirements for the coupling gaps between the IFA antenna, the parasitic antenna, and the watch's metal ring are high, increasing the complexity of the antenna design. Furthermore, in this solution, the IFA antenna and parasitic unit are FPC or LDS antennas placed on an antenna bracket, which undoubtedly occupies the limited space of the watch and is difficult to apply to wearable devices with limited size.

[0050] Based on the deficiencies of the aforementioned related technologies, this disclosure provides a simple and effective circularly polarized antenna structure. This antenna structure can be used in smart wearable devices to achieve a circularly polarized antenna. It is understood that the smart wearable devices described in the following embodiments of this disclosure can be any suitable device form, such as smartwatches, smart bracelets, and other watch-type devices; smart glasses, VR glasses, AR glasses, and other glass-type devices; smart clothing, wearable devices, etc.; etc., and this disclosure does not impose any limitations on these.

[0051] like Figure 1As shown, in some embodiments, the antenna structure of this disclosure includes a main board 100 and a ring-shaped radiator 200. The main board 100 is the main PCB board of the device, on which a processor and corresponding control circuit modules are integrated (not shown in the figures). The radiator 200 is a ring-shaped metal radiator, such as a metal ring, and is disposed above or outside the main board 100, thereby forming a gap between the radiator 200 and the main board 100. The radiator 200 and the main board 100 are electrically connected through a feed terminal 110 and a ground terminal 120. The feed terminal is connected to the feed module of the main board through a feed point 111, and the ground terminal 120 is connected to the ground module of the main board through a first capacitor 121, thereby forming an antenna structure.

[0052] The power supply terminal 110 spans the gap formed 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 it can be integrally formed; this disclosure does not impose any limitations on this. In one example, the power supply terminal 110 is integrally formed 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 on the motherboard 100, wherein the connection between the power supply terminal 110 and the motherboard 100 forms a power supply point 111.

[0053] The grounding terminal 120 is also connected across the gap formed between the motherboard 100 and the radiator 200. That is, one end of the 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 is 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.

[0054] Continue to refer to Figure 1 The grounding terminal 120 is connected to a first capacitor 121, and the radiator 200 is grounded through the first capacitor 121. Specifically, the first capacitor 121 can be set on the motherboard 100, with one end connected to one end of the grounding terminal 120 and the other end connected to the grounding module of the motherboard 100.

[0055] 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.

[0056] 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.

[0057] 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 allows for 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 this disclosure refers to the effective electrical length of the radiator that actually generates resonant electromagnetic waves, and is not limited to the physical length.

[0058] At least one inventive concept of the antenna structure disclosed herein is that by directly feeding the ring radiator 200 and using a grounded first capacitor 121 to generate current in the radiator 200 to pull it into a rotating ring current, a circularly polarized wave is formed. The principle and performance of the circularly polarized wave generation will be explained in detail below and will not be elaborated here.

[0059] As described above, the circularly polarized antenna structure of this embodiment can realize the circularly polarized antenna form of the device, thereby achieving more accurate positioning when performing satellite positioning functions. Furthermore, by directly feeding the ring radiator, there is no need to set up other coupled antenna structures, which greatly simplifies the structure and reduces the cost of the circularly polarized antenna, making it easier to implement in devices with limited space, such as watches.

[0060] The following is combined Figures 1 to 3 This document provides a specific embodiment of the antenna structure and its implementation principle, detailing the process. In this embodiment, a smartwatch is used as an example of a smart wearable device, and the antenna structure is exemplified by a satellite positioning antenna for the watch.

[0061] like Figure 2As shown, the smartwatch includes a casing, which comprises a frame 310 and a bottom casing 320. Electrical components such as a battery 400 and a motherboard 100 are housed inside the casing. It is worth noting that the bottom casing 320 in this embodiment can be made of non-metallic materials such as plastic, or it can be made of metal; this disclosure does not impose any limitations. The open end on the upper side of the casing generally serves as the display area of ​​the watch. In this embodiment, the radiator 200 of the antenna structure is implemented using the watch's metal bezel. The metal bezel is located on the end face of the open end of the casing. Due to its metallic texture, it serves both a decorative purpose and can be used to mount the screen assembly 500. In this embodiment, using the metal bezel 200 as the radiator of the antenna structure significantly reduces the space occupied by the antenna structure inside the watch, and the larger radiator also greatly enhances the antenna's radiation performance.

[0062] like Figure 3 As shown, in this embodiment, the feed terminal 110 and the ground terminal 120 are integrally formed with the metal frame. During assembly, they are electrically connected to subsequent circuit modules via spring contacts 130 provided on the main board 100. The screen assembly 500 is fixedly assembled to the open end of the housing via the metal frame. For ease of explanation of the antenna structure, Figure 1 The structure of the watch has been simplified, showing only the structure related to the circularly polarized antenna.

[0063] The following is based on Figure 1 The structure shown illustrates the implementation principle of the circularly polarized antenna in this embodiment.

[0064] Firstly, circularly polarized antennas can be implemented in two ways: the first is that a loop current with an effective perimeter that is an integer multiple of the wavelength can form circular polarization; the second is that two line currents with equal amplitude and orthogonality and a 90° phase difference can form circular polarization. The circularly polarized antenna in this embodiment is implemented using the first method. In this embodiment, taking a GPS signal with a center operating frequency of 1.575 GHz as an example, the wavelength of the GPS signal can be calculated from the center operating frequency. At the same time, based on the influence of components such as the watch case and screen on the wavelength, the actual physical perimeter of the metal frame under this effective wavelength can be designed.

[0065] For a metal frame with an effective perimeter of one GPS signal wavelength, in this embodiment of the present disclosure, the metal frame is directly fed with electricity, and the first capacitor 121 is used to effectively pull the generated current, so that a rotating current field with unidirectional rotation is formed inside the metal frame.

[0066] like Figure 4 As shown, Figure 4The diagram shows the current distribution of the rotating current generated by the metal frame over one cycle. Figures a through d represent the current distribution at phases of 0°, 90°, 180°, and 270°, respectively. Darker areas indicate higher current density, while lighter areas indicate lower current density. Observing the change in the position of the current zero point in figures a through d reveals that, under the action of the first capacitor 121, a counter-clockwise rotating circular current is generated inside the metal frame. According to the right-hand rule, this spiral current generates a circularly polarized wave in the +z direction (perpendicular to the paper and outwards), thus forming an effective right-hand circularly polarized antenna.

[0067] The antenna performance and influencing factors of the circularly polarized antenna in this embodiment will be further explained below. For ease of explanation, the display plane of the watch is defined as the xy plane, and the direction perpendicular to the watch screen pointing towards the sky is defined as the +z direction, thereby establishing an xyz spatial rectangular coordinate system. Furthermore, as... Figure 5 As shown, the direction of counterclockwise rotation is defined as the first direction, the line connecting the power supply terminal 110 and the center of the metal frame is the first line, the line connecting the grounding terminal 120 and the center of the metal frame is the second line, and the angle between the first line and the second line is the first angle β.

[0068] like Figure 5 As shown, 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 4 (As can also be seen). Therefore, at a certain moment, the entire circumference can be divided into four regions based on the current distribution, namely:

[0069] In this region, the current rises from zero at 0° to a peak at 90°.

[0070] In this region, the current drops from a peak value at 90° to zero at 180°;

[0071] In this region, the current rises from zero at 180° to a peak at 270°.

[0072] In this region, the current drops from a peak value of 270° to zero value of 360°.

[0073] The aforementioned current distribution is a periodic current variation distribution. Under the action of the first capacitor 121, this periodic current distribution will rotate periodically within the annular metal frame over time, thus forming a circularly polarized wave. Furthermore, when the current rotates clockwise within the metal frame, a left-handed circularly polarized wave is generated, while when the current rotates counterclockwise within the metal frame, a right-handed circularly polarized wave is generated.

[0074] Furthermore, due to the rotation caused by the current in the metal frame under the action of the first capacitor 121, 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 121, the traction current rotates clockwise. This is because the phase of the current across the first capacitor 121 in the AC circuit leads the phase of the voltage across it by 90°. Therefore, when the first angle is 121... At this time, the aforementioned 90° 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 first included angle... When the current phase across the first capacitor 121 is 90° ahead, the current on the ring radiator 200 will rotate clockwise, thus realizing a left-hand circularly polarized antenna.

[0075] 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 a circularly polarized antenna 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.

[0076] Therefore, considering that satellite positioning antennas all use right-hand circularly polarized antennas, when the antenna structure is used as a satellite positioning antenna, it should also be a right-hand circularly polarized antenna. Therefore, when used as a satellite positioning antenna, the first included angle β is preferably... Of course, those skilled in the art will understand that in other embodiments, the first included angle β can also be set to... This forms a left-hand circularly polarized antenna.

[0077] Furthermore, as mentioned above, a circularly polarized wave can be decomposed into two orthogonal linearly polarized waves with equal amplitude and a 90° phase difference. Simultaneously, based on the current distribution of the resonant wave, the current zero point of the first-order mode corresponds to the current peak value of the other-order mode. Therefore, to enhance the effect of the first capacitor 121 on circular polarization, its position should be as far away as possible from these current zero points, i.e., the first included angle β should be far from positions of 0°, 90°, 180°, and 270°.

[0078] Furthermore, since the satellite positioning antenna in this embodiment only considers right-hand circular polarization, and considering that smartwatches contain many other components such as the screen and heart rate monitoring FPC, side buttons, and speakers, the feed terminal 110 and ground terminal 120 should be as close as possible to avoid these components affecting antenna performance. Therefore, in a preferred embodiment, the first included angle β is preferably 10° to 80°.

[0079] After determining the range of the first included angle β to be 10° to 80°, the antenna structure can be further optimized.

[0080] Axial ratio is an important parameter characterizing the performance of a circularly polarized antenna. It refers to the ratio of the 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 application scenario of this embodiment, a criterion for evaluating the performance of a circularly polarized antenna is that the axial ratio should be less than 3 dB.

[0081] On the other hand, since a core aspect of the circularly polarized antenna in this embodiment is the use of a first capacitor to pull the current through the metal frame, the pulling effect achieved by capacitors of different capacitance values ​​varies. Through extensive comparative experiments, the capacitance value of the first capacitor, the first included angle β, and the operating frequency range with an axial ratio less than 3dB satisfy the following relationship:

[0082] When the capacitance of the first capacitor remains constant, the operating frequency range with a axial ratio less than 3dB decreases as the first included angle β increases; when the first included angle β remains constant, the operating frequency range with a axial ratio less than 3dB decreases as the capacitance increases. Furthermore, when the first included angle β is less than 45°, the operating frequency range with a axial ratio less than 3dB shows a smaller trend with the capacitance of the first capacitor; conversely, when the first included angle β is greater than 45°, the operating frequency range with a axial ratio less than 3dB shows a larger trend with the capacitance of the first capacitor. Moreover, when the first included angle β is less than 45°, a first capacitor with a larger capacitance can be used; conversely, when the first included angle β is greater than 45°, a first capacitor with a smaller capacitance can be used. The capacitance value (unit: pF, picofarad) of the first capacitor can be between 0.2pF and 1.5pF.

[0083] Based on the above characteristics, the circularly polarized antenna can be optimized by adjusting the first included angle β and the capacitance value of the first capacitor. The optimization goal is to ensure that the antenna's operating frequency bandwidth meets the frequency of the satellite positioning antenna, while the axial ratio of this frequency bandwidth is less than 3dB.

[0084] In one example, when the first included angle β is 25° and the capacitance of the first capacitor is 0.5pF, the optimization requirement is met, that is, to realize a satellite positioning antenna with right-hand circular polarization and a working frequency bandwidth axial ratio of less than 3dB. Figure 6 The example shows the antenna return loss curve of the watch when it is worn on the arm. Figure 7 The antenna efficiency curve of this example watch when worn on the arm is shown. Figure 6 and Figure 7 As can be seen, the antenna in this embodiment has good return loss and antenna efficiency in the satellite positioning frequency bandwidth. Figure 8 The curve showing the change in the antenna axial ratio as a function of frequency for the watch in this example when it is worn on the arm is illustrated. Figure 9 The diagram shows the right-hand and left-hand rotation gain of the antenna as a function of frequency when the watch in this example is worn on the arm. Figure 8 As can be seen, the antenna in this embodiment has an axial ratio of less than 3dB within the satellite positioning frequency bandwidth, which meets the right-hand circular polarization requirements of satellite positioning antennas such as GPS, BeiDou, and GLONASS. Furthermore, for a high-performance right-hand circular polarization antenna, the gain of its right-hand polarized wave should be at least 10dB higher than the gain of its left-hand polarized wave. Figure 9 It can be seen that the gain of the right-hand circularly polarized wave of the antenna in this example is more than 15dB higher than that of the left-hand circularly polarized wave, and it has good right-hand circular polarization performance, which further proves that the antenna of the present invention has better antenna performance.

[0085] To further illustrate the performance of this example antenna, we will use a GPS satellite positioning antenna with a center operating frequency of 1.575 GHz as an example to further explain the antenna performance.

[0086] Figure 10 The following diagram shows the radiation pattern of the right-hand circularly polarized wave from the antenna of this example watch in the xoz plane when it is worn on the arm. Figure 11 This diagram shows the radiation pattern of the antenna of this example watch in the yoz plane with right-hand circularly polarized waves when worn on the arm. Figure 10 and Figure 11 As can be seen, the maximum gain of this example antenna occurs above the arm, perfectly meeting the three main application scenarios of a watch when worn: when raising the wrist to check the watch, the watch's direction (+z direction) points to the sky; when running or walking, the 6 o'clock position points to the sky when the arm swings; and the 9 o'clock position points to the sky when the arm swings. Therefore, this example antenna has excellent radiation efficiency as a satellite positioning antenna, greatly improving antenna performance. Furthermore, through... Figure 10It can also be seen that the antenna radiation has good symmetry in the xoz plane, which also shows that the antenna in this example has good consistency for wearing on the left and right hands, and can meet the needs of users who wear watches on both the left and right hands at the same time.

[0087] Figure 12 This example shows the antenna in the case of the watch being worn on the arm. Figure 10 The curve showing the gain variation of the radiated wave with angle θ on the xoz plane is shown. Figure 13 The antenna is shown in Figure 11 The curve showing the gain variation of the radiated wave with angle θ on the yoz plane is shown. Figure 12 and Figure 13 The results show that the gain of the right-hand circularly polarized wave and the total gain of the antenna are well consistent within ±60° in both the xoz and yoz planes. This further proves that the right-hand circularly polarized antenna in this example has good antenna performance in space and can meet the requirements of rapid satellite search and accurate navigation.

[0088] The structure and principle of the circularly polarized antenna structure of the present disclosure have been described in detail above. Based on the above embodiments, the present disclosure may also have other alternative embodiments suitable for implementation.

[0089] In some alternative implementations, the radiator of the aforementioned smartwatch is not limited to using a metal frame. For example... Figure 14 In the illustrated embodiment, the radiator 200 is set as part of the middle frame, that is, the radiator 200 and the frame 310 together form the middle frame structure of the watch. Other structures and assembly methods of the watch in this embodiment are as described above and will not be repeated here. In this embodiment, the radiator 200 is positioned in the middle frame, thereby effectively increasing the volume of the radiator and greatly enhancing the radiation efficiency of the antenna. Of course, those skilled in the art will understand that the radiator 200 can also be implemented using any other suitable structural form, which will not be elaborated upon here.

[0090] In other embodiments, the antenna structure of this disclosure is not limited to smartwatches, but can also be any other suitable smart wearable device, such as smart bracelets, smart headphones, etc., and this disclosure does not impose any limitations on it. It is also understood that when the antenna structure is applied to other forms of smart wearable devices, the radiator can also be implemented using other structures accordingly, and the ring structure of the radiator does not need to be limited to a circular ring; any other form of ring can be implemented. For example, in some examples, the ring structure of the radiator can also be a rectangular ring, a rounded rectangular ring, a rhombus ring, a triangular ring, or other polygonal rings, and this disclosure does not impose any limitations on it.

[0091] In some alternative embodiments, the antenna structure of this disclosure is not limited to implementing a satellite positioning antenna, but can also be any other suitable antenna type, such as a Bluetooth antenna, a WiFi antenna, or a 4G / 5G antenna. Where device size and space permit, the antenna structure of this disclosure can implement any type of circularly polarized antenna, and this disclosure does not impose any limitations on this.

[0092] As described above, the circularly polarized antenna structure provided in this disclosure can be implemented in smart wearable devices, thereby improving the antenna receiving efficiency and performance, and enhancing positioning accuracy. Furthermore, the structure for implementing a circularly polarized antenna is simple, requiring no coupling with other structures, greatly simplifying the structure and reducing cost, and making it easier to implement in smaller smart wearable devices. Moreover, the antenna structure according to this disclosure has better circular polarization performance, which can further improve positioning accuracy.

[0093] Secondly, this disclosure provides a smart wearable device that includes the circularly polarized antenna structure described in any of the above embodiments, thereby enabling the implementation of a circularly polarized antenna on the device and improving the device's antenna performance.

[0094] Specifically, smart wearable devices can be any wearable device suitable for implementation, such as smartwatches, smart bracelets, smart headphones, or smart glasses, and this disclosure does not limit them.

[0095] In one example, the smart wearable device is a smartwatch, the structure of which can be seen above. Figure 2 and Figure 14 The implementation methods are described in detail herein. The smartwatch includes the satellite positioning antenna found in any of the above embodiments. In one example, the smartwatch includes a GPS satellite positioning antenna, which is implemented using the circularly polarized antenna structure described in the above embodiments. Of course, any other suitable antenna type can be implemented, and these will not be elaborated upon here.

[0096] As described above, the smart wearable device provided by this disclosure includes a circularly polarized antenna structure, thereby implementing a circularly polarized antenna on the smart wearable device, improving the antenna reception efficiency and antenna performance, and enhancing positioning accuracy. Furthermore, the structure of the circularly polarized antenna is simple, requiring no coupling with other structures, greatly simplifying the structure and reducing cost, and making it easier to implement in smaller smart wearable devices. Moreover, the smart wearable device according to this disclosure has better circularly polarized antenna performance, further improving positioning accuracy.

[0097] 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 are still within the scope of protection of this disclosure.

Claims

1. A circularly polarized antenna structure, characterized in that, The antenna structure, used in smart wearable devices, includes: Motherboard; A ring-shaped radiator, the effective electrical length of which is equal to the wavelength corresponding to the center operating frequency of the antenna structure, and a gap is formed between the radiator and the motherboard; A power supply terminal, bridging the motherboard and the radiator, has one end electrically connected to the radiator and the other end connected to the power supply module of the motherboard; and The grounding terminal has one end electrically connected to the radiator and the other end electrically connected to the grounding module of the motherboard through the first capacitor. The first capacitor is used to draw the current on the radiator so that the radiator generates an effective rotating ring current to form a circularly polarized antenna.

2. The antenna structure according to claim 1, characterized in that, The line connecting the power supply terminal and the center point of the radiator is the first line, and the line connecting the ground terminal and the center point of the radiator is the second line; the counterclockwise circumferential direction of the radiator is the first direction, and along the first direction, the first line and the second line form a first included angle β; in, or, 3. The antenna structure according to claim 2, characterized in that, The first included angle β is 10° to 80°.

4. The antenna structure according to any one of claims 1 to 3, characterized in that, The annular structure of the radiator is any one of the following: Circular rings, elliptical rings, rectangular rings, rhomboid rings, or polygonal rings.

5. The antenna structure according to any one of claims 1 to 3, characterized in that, The antenna structure can be any one of the following: Satellite positioning antenna, Bluetooth antenna, WiFi antenna or 4G / 5G antenna.

6. The antenna structure according to any one of claims 1 to 3, characterized in that, The capacitance of the first capacitor is 0.2pF to 1.5pF.

7. A smart wearable device, characterized in that, Including the antenna structure according to any one of claims 1 to 6.

8. The smart wearable device according to claim 7, characterized in that, The smart wearable device is a smartwatch, and the smartwatch includes: The housing, wherein the main board is disposed within the housing; and A metal frame surrounds the edge of the open end of the housing, forming the radiator.

9. The smart wearable device according to claim 8, characterized in that, The smartwatch also includes a screen assembly, which is mounted to the open end of the housing via the metal frame.

10. The smart wearable device according to claim 7, characterized in that, The smart wearable device is any one of the following: Smart bracelets, smartwatches, smart earphones, or smart glasses.

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