Circularly polarized antenna and wearable electronic device using same

Abstract

The embodiment of the utility model relates to a circularly polarized antenna. The circularly polarized antenna comprises an open-ring-shaped radiator and a floor, the open-ring-shaped radiator is located on one side of the floor, a gap is formed between the open-ring-shaped radiator and the floor, the open-ring-shaped radiator is of an axisymmetric structure and is provided with a feeding point and a grounding point, and the feeding point and the grounding point are symmetrically arranged relative to the symmetric axis of the open-ring-shaped radiator. The open-ring-shaped radiator is connected with a feed signal at a feed point through a feed terminal and is connected with the floor at a grounding point through a grounding terminal, and two branches of the open-ring-shaped radiator are respectively formed between the feed point and the end part of the adjacent open-ring-shaped radiator and between the grounding point and the end part of the adjacent open-ring-shaped radiator; the floor is of an axisymmetric structure and has the same symmetry axis as the radiator. The embodiment of the utility model also relates to wearable electronic equipment applying the circularly polarized antenna. According to the embodiment of the invention, the circular polarization characteristic of the antenna is realized through the simple structure of the open-ring-shaped radiator by utilizing the odd-even mode excitation principle of the two branches.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to a circularly polarized antenna and wearable electronic devices using the same. Background Art

[0002] In the field of wearable electronic devices, such as smart watches, bracelets, glasses, etc., positioning accuracy has always been a pain point that people are concerned about. The positioning antennas of traditional wearable electronic devices are mostly linearly polarized antennas, but the positioning signals sent by the satellite system are right-hand circularly polarized signals after passing through the ionosphere. Therefore, the positioning antennas of wearable electronic devices cannot receive all the positioning signals sent by navigation satellites. In addition, the right-hand circularly polarized signals sent by navigation satellites will become left-hand circularly polarized signals after being reflected an odd number of times by objects such as the ground, tall buildings, and trees, thereby generating multipath interference, which will seriously affect the positioning effect of the entire wearable electronic device. Utility Model Content

[0003] According to the first aspect of the present application, a circularly polarized antenna is provided, which is applied to wearable electronic devices, including: an open-loop radiator and a floor, wherein the open-loop radiator is located on one side of the floor and forms a gap with the floor, the open-loop radiator is an axisymmetric structure, has a feeding point and a grounding point, and the feeding point and the grounding point are symmetrically arranged relative to the symmetry axis of the open-loop radiator, the open-loop radiator is connected to a feeding signal through a feeding terminal at the feeding point, and is connected to the floor through a grounding terminal at the grounding point, and the feeding point and the grounding point respectively form two branches of the open-loop radiator with the ends of the open-loop radiator adjacent to each other; the floor is an axisymmetric structure and has the same symmetry axis as the radiator.

[0004] In some embodiments, the open-ring radiator and the open-ring radiator are in one of the following shapes with an opening: a circular ring, an elliptical ring, a quadrilateral, and a polygonal shape.

[0005] In some embodiments, the open-loop radiator is in the shape of a circular ring with an opening or a rectangular frame with an opening.

[0006] In some embodiments, a circumferential length of one end of the open-loop radiator adjacent to the feeding point is smaller than a circumferential length of another end of the open-loop radiator adjacent to the grounding point.

[0007] In some embodiments, the feeding point is located adjacent to the grounding point.

[0008] In some embodiments, a projection of the open-loop radiation on the floor overlaps an outer contour edge of the floor.

[0009] In some embodiments, the width of the open-loop radiator is 3 mm.

[0010] In some embodiments, the gap between the open-loop radiator and the floor is in the range of [2mm, 4mm].

[0011] According to a second aspect of the present application, a wearable electronic device is provided, comprising the aforementioned circularly polarized antenna.

[0012] In some embodiments, the floor is a grounding layer in a mainboard of the wearable electronic device, at least a feeding module is disposed on the mainboard, and the open-loop radiator is electrically connected to the feeding module via a feeding terminal.

[0013] In some embodiments, the outer contour of the mainboard of the wearable electronic device is circular or rectangular. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other objects, features and advantages of the present application will become more apparent through a more detailed description of exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0015] Figure 1 An exemplary circuit structure diagram of a wearable electronic device provided by the present application is shown;

[0016] Figure 2 A structural diagram of a circularly polarized antenna provided according to an embodiment of the present application is shown;

[0017] Figure 3-a A feeding signal current distribution diagram of a circularly polarized antenna in Mode 1 provided according to an embodiment of the present application is shown;

[0018] Figure 3-b A feeding signal current distribution diagram of a circularly polarized antenna in Mode 2 provided according to an embodiment of the present application is shown;

[0019] Figure 4 A curve showing a change in S11 of a circularly polarized antenna according to an embodiment of the present application as a function of frequency is shown;

[0020] Figure 5 A curve showing a change in the axial ratio of a circularly polarized antenna according to an embodiment of the present application as a function of frequency is shown. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] The circular polarization antenna scheme applied to wearable electronic devices in the present application scheme will be described in detail below in combination with the satellite positioning principle and the basic structure of wearable electronic devices.

[0024] When positioning is achieved through satellite signals, a receiver is generally required, and according to the principle of implementing positioning, the receiver generally includes an antenna unit, a receiving unit and a processing unit. The antenna unit receives the satellite signals it tracks, for example, supports receiving one or more satellite signals in the Global Positioning System (GPS) of the United States, the Global Navigation Satellite System (GLONASS) of Russia, the Beidou Star Positioning System of China, the Galileo System (Galileo) of Europe, the Quasi-Zenith Satellite System (QZSS) of Japan, and the Regional Navigation Positioning System of India. The receiving unit can demodulate the satellite orbit parameters and other data according to the pseudo-distance from the receiving antenna to the satellite and the rate of change of the distance. Based on these data, the processing unit calculates the distance between the geographical location to be located (such as the geographical location of the wearable electronic device) and the satellite by calculating the propagation time of the satellite signal. When the antenna unit receives satellite signals from multiple satellites at the same time, the processor uses a triangulation positioning algorithm to calculate the longitude and latitude, altitude, speed, time and other information of the geographical location to be located (such as the geographical location of the wearable electronic device).

[0025] Wearable electronic devices are integrated with positioning functions or positioning services. Wearable electronic devices can monitor the movement distance and movement trajectory of human users through location positioning. Without the need for human users to carry mobile terminals (such as smart phones), wearable electronic devices can record the trajectory of the current movement scene. By pairing with the mobile terminal, users can also view exercise data such as exercise distance, movement trajectory, exercise steps, calorie consumption, heart rate, etc. through the APP on the mobile terminal.

[0026] Wearable electronic devices may be, for example, smart watches, smart bracelets, smart glasses, etc., or may be other electronic devices that can provide positioning functions or positioning services and can be carried by human users by wearing or other wearing methods.

[0027] See also Figure 1 The schematic diagram of the circuit structure of the wearable electronic device shown in the figure shows an exemplary circuit structure of the wearable electronic device 100, wherein the wearable electronic device 100 includes a storage and processing circuit 10, and the storage and processing circuit 10 may include a memory, such as a hard disk drive memory, a non-volatile memory (e.g., a flash memory or other electrically programmable read-only memory configured to form a solid-state drive), a volatile memory (e.g., a static random access memory or a dynamic random access memory), etc. The processing circuit in the storage and processing circuit 10 can be used to control the operation of the wearable electronic device 100. The processing circuit can be based on one or more microprocessors, microcontrollers, digital signal processors, application-specific integrated circuits, etc. The storage and processing circuit 10 can be used to run software on the wearable electronic device 100, such as an Internet browsing application, a Voice over Internet Protocol (VOIP) phone call application, an email application, a media playback application, an operating system function, etc. In order to support interaction with an external device, the storage and processing circuit 10 can be used to implement a communication protocol. Communication protocols that may be implemented using storage and processing circuitry 10 include Internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as such), protocols for other short-range wireless communication links such as protocols, cellular telephone protocols, multiple-input multiple-output (MIMO) protocols, antenna diversity protocols, and the like.

[0028] The wearable electronic device 100 may also include input-output circuitry 20, which may include input-output devices 21. The input-output devices 21 may be used to allow data to be provided to the wearable electronic device 100 and to allow data to be provided from the wearable electronic device 100 to an external device. The input-output devices 21 may include user interface devices, data port devices, and other input-output components. For example, the input-output devices 21 may include, for example, a touch screen, a display without touch sensor capabilities, a button, a joystick, a scroll wheel, a trackpad, a keypad, a keyboard, a microphone, a camera, a button, a speaker, a status indicator, a light source, an audio jack and other audio port components, a digital data port device, a light sensor, a motion sensor (accelerometer), a capacitive sensor, a proximity sensor, a fingerprint sensor (e.g., a fingerprint sensor integrated with a button), etc.

[0029] The wearable electronic device 100 may also include a wireless communication circuit 30 for wirelessly communicating with an external device. The wireless communication circuit 30 may include a radio frequency (RF) transceiver circuit formed by one or more integrated circuits, a power amplifier circuit, a low noise input amplifier, a passive radio frequency (RF) component, one or more antennas, a transmission line, and other circuits for processing radio frequency (RF) wireless signals, such as Figure 1 As shown, the radio frequency transceiver circuit may specifically include at least one of a satellite positioning receiver circuit 31, a local wireless transceiver circuit 32 (e.g., WiFi, Bluetooth), and a long-range wireless transceiver circuit 33 (e.g., a cellular phone transceiver circuit). The local wireless transceiver circuit 32 may process 2.4 GHz and 5 GHz bands for (IEEE 802.11) communications and may process 2.4 GHz communication bands; the long-range wireless transceiver circuit 33 may be used to process wireless communications in a frequency range, such as a low communication band from 700 MHz to 960 MHz, a low-medium communication band from 1400 MHz to 1520 MHz, a medium communication band from 1710 MHz to 2170 MHz, and a high communication band from 2300 MHz to 2700 MHz, or other communication bands between 700 MHz and 4000 MHz. If necessary, the wireless communication circuit 30 may include circuits for other short-range and long-range wireless links. For example, the wireless communication circuit 30 may include a near field communication (NFC) circuit; the satellite positioning receiver circuit 31 is used to receive and process GPS satellite signals at 1575 MHz or satellite signals of other satellite systems (eg, GLONASS satellite signals at 1609 MHz).

[0030] The wireless communication circuit 30 may include one or more antennas 34, and any suitable antenna type may be used to form the antenna 34. For example, the antenna 34 may include an antenna having a resonant element, and the antenna is formed by a combination of one or more of a loop antenna structure, a patch antenna structure, a dipole antenna structure, a monopole antenna structure, an inverted F-shaped antenna structure, a slot antenna structure, a planar inverted F-shaped antenna structure, a helical antenna structure, etc. Different types of antennas may be used for different frequency bands and frequency band combinations. For example, one type of antenna may be used when forming an antenna for a local wireless link, another type of antenna may be used when forming an antenna for a remote wireless link, and antennas other than the above two types may be used when forming a positioning antenna.

[0031] Considering that the positioning signal sent by the satellite system is a right-hand circularly polarized signal after passing through the ionosphere, for wearable electronic devices, the use of circularly polarized antennas can effectively suppress the polarization mismatch of the antenna. At the same time, the right-hand circularly polarized radiation generated by the radiator in the right-hand circularly polarized antenna can also filter the left-hand circularly polarized satellite signal reflected by high-rise buildings or the ground, so as to reduce multipath interference and enable wearable electronic devices to have a better positioning effect.

[0032] See also Figure 2 As shown, Figure 2 A schematic diagram of a circularly polarized antenna structure of the present application is shown. The circularly polarized antenna 200 (for example, Figure 1 The antenna 34 can be applied to a wearable electronic device, which includes an open-loop radiator 210 and a floor 300, wherein the open-loop is a ring with an opening (for convenience of display, Figure 2 The radiator 210 is a semicircular ring as an example of an open ring shape), and the radiator 210 is located on the floor 300 (for the convenience of display, Figure 2 One side of the floor 300 is circular as an example), thereby forming a gap between the floor 300.

[0033] The radiator 210 and the floor 300 are both axially symmetrical structures and have the same symmetry axis. Figure 2 As shown, the floor 300 is circular, the radiator 210 is semicircular, and the radiator 210 and the floor 300 both have a symmetrical structure with the diameter of the floor 300 as the symmetry axis. In addition, the radiator 210 has a feeding point B and a grounding point A, which are symmetrically arranged relative to the symmetry axis of the radiator 210. The radiator 210 receives a feeding signal through a feeding terminal 220 at the feeding point B, and is connected to the floor 300 through a grounding terminal 230 at the grounding point A. Figure 2An implementation is shown, in which the floor 300 can be a grounding layer in the mainboard of the wearable electronic device, the mainboard is provided with a feeding module, and the radiator 210 is connected to the feeding module on the mainboard through the feeding terminal 220 ( Figure 2 ) to receive the feed signal, and connect to the ground layer ( Figure 2 It is understandable that the floor 300 may also be a separate metal plate, attached to the back of the mainboard away from the feeding module, and the embodiment of the present application does not impose any restrictions on this.

[0034] like Figure 2 As shown, the two ends of the radiator 210 are point C and point D respectively, wherein the BC segment formed by point B and point C on the radiator 210 constitutes branch 1 of the radiator 210, and the AD segment formed by point A and point D on the radiator 210 constitutes branch 2 of the radiator 210. Branch 1, branch 2 and floor 300 can excite the antenna to be in the first radiation mode (Mode 1 mode) and the second radiation mode (Mode 2 mode).

[0035] Among them, the feeding signal current distribution of Mode 1 mode (also called Mode 1 mode as even mode) is as follows: Figure 3-a As shown, the direction of the feeding signal current on branch 1 is from C to B, and the direction of the feeding signal current on branch 2 is from D to A, that is, the feeding signal currents on branch 1 and branch 2 are longitudinally symmetrical, so the longitudinal feeding signal current components cancel each other out, and the transverse feeding signal current components are superimposed on each other and are directed transversely to the left. At the same time, the feeding signal current direction on the floor 300 that forms a folded dipole with branch 1 and branch 2 is transversely to the right. Therefore, the equivalent feeding signal current direction of the antenna 200 in Mode 1 is transversely to the right, and the transverse resonant physical length is 1.5 times the diameter of the floor 300.

[0036] Among them, the feeding signal current distribution of Mode2 mode (also called Mode2 mode is odd mode) is as follows: Figure 3-b As shown, the direction of the feeding signal current on branch 1 is from C to B, and the direction of the feeding signal current on branch 2 is from A to D, that is, the directions of the feeding signal current on branch 1 and branch 2 are longitudinally inversely symmetrical, so the longitudinal feeding signal current components are superimposed on each other and are directed longitudinally downward, and the transverse feeding signal current components cancel each other out. At the same time, the feeding signal current direction on the floor 300 that forms a folded dipole with branches 1 and 2 is longitudinally downward, so the equivalent feeding signal current direction of the antenna in Mode 2 is longitudinally downward, which is exactly perpendicular to the equivalent feeding signal current direction in Mode 1, and the resonant physical length in the longitudinal direction is 1 times the diameter of the floor 300.

[0037] Since the feed signal current distributions of the antenna in Mode 1 and Mode 2 are perpendicular to each other, and at the same frequency, the resonant physical lengths of the antenna in Mode 1 and Mode 2 are also different, there must be a frequency between Mode 1 and Mode 2 at which circular polarization can be achieved, that is, the electric field vectors in the two radiation modes have the same amplitude and a phase difference of 90 degrees.

[0038] In addition, the size of the gap between the radiator 210 and the floor 300 is related to the radiation efficiency of the antenna, that is, the radiation efficiency of the antenna can be changed by adjusting the gap between the radiator 210 and the floor 300. For example, in one implementation of the present application, the gap can be adjusted within [2mm, 4mm].

[0039] The width of the circular ring of the radiator 210 is related to the bandwidth of the antenna, that is, the bandwidth of the antenna can be changed by adjusting the width of the circular ring of the radiator 210. For example, in one implementation of the present application, the width can be set to 3 mm so that the bandwidth of the circular polarization antenna 200 can cover and adapt to the GPS bandwidth.

[0040] The positioning signal sent by the satellite system is a right-hand circularly polarized signal after passing through the ionosphere. In one implementation of the present application, the circularly polarized antenna 200 can be designed as a right-hand circularly polarized antenna. When the circumferential length of branch 1 is less than the circumferential length of branch 2, that is, the circumferential length between the feed point B and one end of the radiator 210 is less than the circumferential length between the grounding point A and the other end of the radiator 210, the radiator 210 can generate right-hand circularly polarized radiation, so that the right-hand circularly polarized antenna 200 can better receive satellite signals. At the same time, the right-hand circularly polarized radiation generated by the radiator 210 can also filter the left-hand circularly polarized satellite signal reflected by a high-rise building or the ground to reduce multipath interference, thereby effectively improving the positioning accuracy of the positioning antenna of the wearable electronic device.

[0041] Of course, if necessary, the circularly polarized antenna 200 can also be designed as a left-hand circularly polarized antenna. When the circumferential length of the branch 1 is greater than the circumferential length of the branch 2, that is, the circumferential length between the feed point B and one end of the radiator 210 is greater than the circumferential length between the ground point A and the other end of the radiator 210, the radiator 210 can generate left-hand circularly polarized radiation. The left-hand circularly polarized antenna can also receive satellite signals, and its receiving effect is half or nearly half of the receiving effect of the right-hand circularly polarized antenna.

[0042] In one implementation of the present application, the feeding point B and the grounding point A may be located adjacent to each other. It is understood that when the feeding point B and the grounding point A are located adjacent to each other, in order to realize a right-hand circularly polarized antenna, the two may be located on both sides of the symmetry axis of the radiator 210 at the same time, for example, Figure 2 shown.

[0043] In the implementation of the present application, the main board on the wearable electronic device may be a printed circuit board (PCB), and the corresponding functions are realized by setting various circuit modules on the main board. Alternatively, the main board may also be other types, such as a combination of a printed circuit board and a flexible printed circuit (FPC), etc., which is not limited in the present application.

[0044] For the circularly polarized antenna 200, a feeding module is provided on the mainboard, for example, a radio frequency feeding circuit, which can be, for example, a radio frequency integrated circuit (IC) chip, and the radio frequency feeding circuit serves as an excitation source of the circularly polarized antenna 200, and is used to feed the radiator 210. A grounding layer is also provided on the mainboard, for example, a reference ground, and the reference ground refers to the GND (Ground) of the circularly polarized antenna 200, which serves as the zero potential plane of the circularly polarized antenna 200, and is usually the copper layer of the mainboard. The "grounding" mentioned in the application is an electrical connection with the reference ground of the mainboard.

[0045] One end of the feed terminal 211 is electrically connected to the radiator 210, and the other end is connected to the RF feed circuit on the mainboard. It is understandable that the connection between the feed terminal 211 and the radiator 210 can be an electrical connection formed by a connecting component, or it can be integrally formed, and the present application does not limit this. In one example, the feed terminal 211 is integrally formed with the radiator 210, and its free end can be directly electrically connected to the RF feed circuit of the mainboard 300. As an alternative, its free end can also be electrically connected to the RF feed circuit of the mainboard through a connector (such as a spring structure) on the mainboard. The ground terminal 212 is also electrically connected to the radiator 210 at one end, and the other end is connected to the reference ground on the mainboard. It is understandable that the connection between the ground terminal 212 and the radiator 210 can be an electrical connection formed by a connecting component, or it can be integrally formed, and the present application embodiment does not limit this. Among them, the ground terminal 212 can be electrically connected to the reference ground on the mainboard through a tuning device, and the tuning device can be, for example, an inductor or a capacitor.

[0046] Taking the target frequency of the circularly polarized antenna 200 as the GPS L1 frequency band (center frequency 1.575 GHz) as an example, if the self-resonant frequency F0 of the radiator 210 is greater than the target frequency, that is, the self-resonant frequency F0 of the radiator 210 is too large, and the self-resonant frequency of the radiator 210 is proportional to its effective electrical length Inversely proportional, that is, the effective electrical length of the radiator 210 is relatively small. When the tuning device uses a capacitor, the ground terminal 240 is connected to the ground 300 through the capacitor. Since the capacitor can flow displacement current, the current path is lengthened, so the effective electrical length of the radiator 210 can be increased by grounding the capacitor. Therefore, for the radiator 210 with a relatively small effective electrical length, its resonant frequency F can be adjusted from the self-resonant frequency F0 to a low frequency.

[0047] Similarly, if the self-resonant frequency F0 of the radiator 210 is less than the target operating frequency, that is, the self-resonant frequency F0 of the radiator 210 is too small, that is, the effective electrical length of the radiator 210 is too large. When the tuning device adopts an inductor, the ground terminal 240 is connected to the ground 300 through the inductor, and relative to the capacitor, the inductor will offset this characteristic of the capacitor and play an opposite effect to the capacitor. Therefore, the effective electrical length of the radiator 210 can be reduced by grounding the inductor, and its resonant frequency F can be adjusted from the self-resonant frequency F0 to a high frequency.

[0048] In another possible implementation, the mainboard of the wearable electronic device is electrically connected to the floor 300, for example, the floor 300 is electrically connected to the mainboard through a spring structure on the mainboard, thereby forming a sandwich structure of the radiator 210, the mainboard and the floor 300, the radiator 210 is electrically connected to the feeding module on the mainboard through the feeding terminal 211, for example, one end of the feeding terminal 211 is electrically connected to the radiator 210, and the other end is connected to the RF feeding circuit on the mainboard, the radiator 210 is electrically connected to the floor 300 through the grounding terminal 212 and the mainboard, for example, one end of the grounding terminal 212 is electrically connected to the radiator 210, and the other end is connected to the conductive layer or conductive area on the mainboard, and is further electrically connected to the floor 300 through the mainboard.

[0049] Finally, it should be noted that Figure 2 It is only an example. The radiator in the present application is a ring with an opening. For example, the width of the ring is 3 mm. However, the embodiment of the present application does not specifically limit the shape of the radiator 210. It can be any of the following shapes with an opening: a circular ring, an elliptical ring, a quadrilateral shape, and a polygonal shape. In addition, the embodiment of the present application does not limit the length of the opening of the radiator 210. The length of the opening can be greater than the length of the radiator 210, or less than the length of the radiator 210, or equal to the length of the radiator 210. For example, Figure 2 The radiator 210 shown in FIG. 1 is in the shape of a semicircular ring, and the length of its opening is equal to the length of the radiator.

[0050] In addition, the embodiment of the present application does not specifically limit the outer contour shape of the mainboard, and it can be any one of the following shapes: circular, elliptical, quadrilateral, polygonal.

[0051] In one implementation of the present application, the shape formed by the open-ring radiator 210 and the opening of the open-ring radiator 210 can be the same as the outer contour shape of the mainboard. For example, the open-ring radiator 210 is a quadrilateral with an opening, and the corresponding outer contour of the mainboard is a quadrilateral.

[0052] Since wearable electronic devices such as smart watches and smart bracelets are usually designed to be circular or rectangular in industrial design (the four sides of the rectangle may also have arc-shaped chamfers), in consideration of saving the design space of wearable electronic devices and making them more compact in space, therefore, in one implementation of the present application, the radiator 210 is a circular ring with an opening, and the outer contour of the corresponding mainboard is circular, or the radiator 10 is a rectangular frame with an opening, and the outer contour of the corresponding mainboard is rectangular.

[0053] In addition, considering the rationality of space design, the projection of the radiator 210 on the floor 300 overlaps with the outer contour edge of the floor 300 .

[0054] Figure 4 Shows Figure 2 The curve of S11 changing with frequency of the circularly polarized antenna 200 is shown in FIG. Figure 5 Shows Figure 2 The curve showing the change of the axial ratio of the circularly polarized antenna 200 with frequency.

[0055] S11 is an important parameter to characterize the performance of the antenna. S11 is the reciprocal of the return loss, and its unit is decibel (dB). The return loss (Return Loss) is a reflection coefficient expressed in logarithmic form. The reflection coefficient is the ratio of the reflected signal power reflected from the antenna's RF input signal to the input signal power, usually expressed in decibels (dB). Ideally, the impedance of the antenna and the RF circuit are perfectly matched, and there is no reflected signal at all. At this time, the return loss is infinitely small. However, in engineering, the impedance of the antenna and the RF circuit cannot be perfectly matched. Therefore, the reflected signal must exist. The worst case is that the RF input signal is completely reflected back, and the return loss is 0. Therefore, the lower the return loss value, the better the antenna performance. For built-in antennas, since the working environment of the antenna is relatively poor, the return loss of the antenna is usually required to be below -7.5dB. For example Figure 4 The change curve shown in the GPS L1 frequency band (center frequency 1.575GHz) is as follows: Figure 4 In the frequency band between the positions marked by the triangle marks 1 and 2 in FIG. 8 , the S11 of the circularly polarized antenna 200 is relatively large, indicating that its return loss is small. The circularly polarized antenna 200 has a good impedance bandwidth in the GPS L1 frequency band and has good antenna performance.

[0056] The axial ratio is an important parameter that characterizes the performance of circularly polarized antennas. The axial ratio refers to the ratio of the two orthogonal electric field components of the circularly polarized wave when the circularly polarized antenna receives or sends signals. The smaller the axial ratio, the better the circular polarization performance. On the contrary, the larger the axial ratio, the worse the circular polarization performance. Figure 5 The change curve shown is in the GPS L1 frequency band (center frequency 1.575GHz). Figure 5 The position marked by the middle triangle mark 1 achieves the requirement of an axial ratio of less than 6dB in a wider frequency band. At a frequency of 1.58HZ, the axial ratio reaches its lowest point, which is 0.6325981dB, and has good circular polarization characteristics.

[0057] In the embodiment of the present application, the circular polarization performance of the antenna can be achieved through a simple radiator structure (branch 1, branch 2) and by utilizing the odd-even mode excitation principle, which has a strong engineering application value.

[0058] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A circularly polarized antenna, characterized in that: The invention is applied to wearable electronic devices, comprising: an open-loop radiator and a floor, wherein the open-loop radiator is located on one side of the floor and forms a gap with the floor, the open-loop radiator is an axisymmetric structure, and has a feeding point and a grounding point, and the feeding point and the grounding point are symmetrically arranged relative to the symmetry axis of the open-loop radiator, the open-loop radiator is connected to a feeding signal through a feeding terminal at the feeding point, and is connected to the floor through a grounding terminal at the grounding point, and the feeding point and the grounding point respectively form two branches of the open-loop radiator with the ends of the open-loop radiator adjacent to each other; the floor is an axisymmetric structure and has the same symmetry axis as the radiator.

2. The circularly polarized antenna according to claim 1, characterized in that: The open-ring radiator is one of the following shapes with an opening: a circular ring, an elliptical ring, and a polygonal frame.

3. The circularly polarized antenna according to claim 2, characterized in that: The open-ring radiator is in the shape of a circular ring with an opening or a rectangular frame with an opening.

4. The circularly polarized antenna according to claim 1, characterized in that: The circumferential length of one end of the open-loop radiator adjacent to the feeding point is smaller than the circumferential length of the other end of the open-loop radiator adjacent to the grounding point.

5. The circularly polarized antenna according to claim 4, characterized in that: The feeding point is located adjacent to the grounding point.

6. The circularly polarized antenna according to claim 1, characterized in that: The projection of the open-loop radiator on the floor overlaps with the outer contour edge of the floor.

7. The circularly polarized antenna according to any one of claims 1 to 5, characterized in that: The width of the open-loop radiator is 3 mm.

8. The wearable electronic device according to any one of claims 1 to 5, characterized in that: The gap between the open-loop radiator and the floor is in the range of [2mm, 4mm].

9. A wearable electronic device, characterized in that: Comprising the circularly polarized antenna as described in any one of claims 1-8.

10. The wearable electronic device according to claim 9, characterized in that: The floor is a grounding layer in a mainboard of the wearable electronic device. At least a feeding module is arranged on the mainboard. The open-loop radiator is electrically connected to the feeding module via a feeding terminal.

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