Circularly polarized antenna and wearable electronic device using same

Abstract

The circularly polarized antenna is applied to wearable electronic equipment and comprises two open-ring-shaped radiators and a floor, the two open-ring-shaped radiators are symmetrically arranged, openings of the two open-ring-shaped radiators are oppositely arranged, and two gaps are formed between the openings of the two open-ring-shaped radiators; any one of the two open-ring-shaped radiators is at least provided with a feeding point and a grounding point, a feeding signal is connected to the feeding point through a feeding terminal, and the grounding point is connected with the floor through a grounding terminal. 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 in all directions through the simple structures of the two adjacent open-loop radiators by utilizing the principle of odd-even mode excitation and mutual coupling effect between the adjacent radiators.

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] Wearable electronic devices for sports scenarios (for example, smart watches, bracelets, glasses, etc.) generally have positioning functions, and the reception performance of positioning signals largely determines the positioning performance of the device. Among them, the positioning antenna of the wearable electronic device, as the first link of the receiving link, plays a key role in the overall receiving performance.

[0003] Positioning antennas are mainly used to receive positioning signals sent by satellite systems. However, the positioning antennas of traditional wearable electronic devices are mostly linearly polarized antennas, but the satellite system transmits to the ground in the form of right-hand circularly polarized electromagnetic waves, which means that the positioning signals sent by the satellite system are right-hand circularly polarized signals after passing through the ionosphere. Therefore, the linearly polarized positioning antennas of wearable electronic devices cannot receive all the right-hand circularly polarized positioning signals sent by navigation satellites.

[0004] Therefore, the positioning antennas in current wearable devices need to be further optimized. Utility Model Content

[0005] According to the first aspect of the present application, a circularly polarized antenna is provided, which is applied to a wearable electronic device, comprising: two open-loop radiators and a floor, wherein the two open-loop radiators are symmetrically arranged, and the openings of the two open-loop radiators are relatively arranged, and the openings of the two open-loop radiators form two gaps between each other; any one of the two open-loop radiators has a feeding point and a grounding point, a feeding signal is connected at the feeding point through a feeding terminal, and the grounding point is connected to the floor through a grounding terminal.

[0006] In some embodiments, the two open-ring radiators and the two gaps between the two open-ring radiators form one of the following shapes: a circular ring, an elliptical ring, a quadrilateral, or a polygonal ring.

[0007] In some embodiments, the gap between the two open-loop radiators ranges from [0.1 mm, 0.3 mm].

[0008] In some embodiments, the angle between the line connecting the center points of the two slots and the feeding point and the center line of symmetry of the two open-loop radiators is in the range of [30°, 60°].

[0009] In some embodiments, projections of the two open-loop radiations on the floor overlap with outer contour edges of the floor.

[0010] In some embodiments, the feeding point and the grounding point are the same point, and the feeding terminal and the grounding terminal are the same terminal.

[0011] In some embodiments, a center of a shape formed by the two open-loop radiators and the gap between the two open-loop radiators overlaps with a center of the floor.

[0012] In some embodiments, the gap between the open-loop radiator and the floor is in the range of [2mm, 4mm].

[0013] According to a second aspect of the present application, a wearable electronic device is provided, comprising the aforementioned circularly polarized antenna.

[0014] In some embodiments, the floor is a grounding layer in the mainboard of the wearable electronic device, the mainboard is provided with at least a feeding module, and the open-loop radiator is electrically connected to the feeding module via a feeding terminal. In some embodiments, the outer contour of the mainboard of the wearable electronic device is circular or rectangular. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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.

[0016] Figure 1 An exemplary circuit structure diagram of a wearable electronic device provided by the present application is shown;

[0017] Figure 2-a A three-dimensional schematic diagram of a circularly polarized antenna structure provided according to an embodiment of the present application is shown;

[0018] Figure 2-b A schematic top view of a circularly polarized antenna structure provided according to an embodiment of the present application is shown;

[0019] Figure 2-c A schematic diagram of electrical connection of a circularly polarized antenna feed terminal provided according to an embodiment of the present application is shown;

[0020] Figure 3 A feeding signal current distribution diagram of a circularly polarized antenna in Mode 1 and Mode 2 provided according to an embodiment of the present application is shown;

[0021] Figure 4 shows the spherical radiation pattern of an omnidirectional circularly polarized antenna;

[0022] Figure 5A 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;

[0023] Figure 6 The graph shows a curve of the axial ratio changing with frequency at two cross-sectional positions in the spherical radiation pattern of a circularly polarized antenna provided according to an embodiment of the present application;

[0024] Figure 7-a The spatial simulation diagram of the antenna gain corresponding to the right-hand circularly polarized antenna when radiating omnidirectionally is shown;

[0025] Figure 7-b The figure shows the spatial simulation diagram of the antenna gain corresponding to the left-hand circularly polarized antenna when it radiates omnidirectionally. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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).

[0030] 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.

[0031] 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.

[0032] See also Figure 1The 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.

[0033] 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.

[0034] 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 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 wireless signals, such as Figure 1As 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).

[0035] 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.

[0036] Considering that the positioning signal sent by the satellite system is usually a right-hand circularly polarized signal after passing through the ionosphere, for wearable electronic devices, the use of a right-hand circularly polarized antenna can effectively suppress the polarization mismatch of the antenna. In addition, since the wearable electronic device will change position as the user moves (for example, swinging the arm), it will also affect the reception performance of the circularly polarized antenna located thereon for the right-hand circularly polarized signal. For example, for the right-hand circularly polarized antenna, when the user's arm is in a horizontal plane, its reception performance for the circularly polarized signal is the best, and when the user's arm is swung to other positions, its reception performance for the circularly polarized signal will become weak. Therefore, in order to make the reception performance of the circularly polarized antenna as unaffected as possible by the position change of the wearable electronic device, it is necessary to design an omnidirectional circularly polarized antenna.

[0037] See also Figure 2-a As shown, Figure 2-a A three-dimensional 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 two open-loop radiators 210 and 220 and a floor 300. The open-loop is a ring with an opening. For the convenience of display, Figure 2-a In the figure, the radiator 210 and the radiator 220 are both semicircular as an example of an open ring shape, and the radiator 210 and the radiator 220 are located on the floor 300 (for the convenience of display, Figure 2-a The outer contour of the floor 300 is a circle as an example) on one side, thereby forming a gap with the floor 300. The radiator 210 and the radiator 220 are symmetrically arranged, and the openings of the two are arranged opposite to each other, and two gaps D are formed between the openings of the radiator 210 and the radiator 220. There is a feeding point and a grounding point on any one of the radiators 210 and the radiator 220, for example, Figure 2-a In the figure, the radiator 210 has a feeding point and a grounding point as an example. The radiator 210 receives a feeding signal through a feeding terminal 230 at the feeding point and is connected to the floor 300 through a grounding terminal at the grounding point.

[0038] See also Figure 2-b As shown, Figure 2-b A schematic top view of a circularly polarized antenna structure of the present application is shown, wherein the radiator 210 and the radiator 220 have symmetrical center lines at relative positions. Figure 2-b The dashed line shown, the line connecting the feed point B and the origin of the center line forms an angle β with the center line.

[0039] The radiators 210, 220 and the floor 300 can excite the circularly polarized antenna 200 to be in the first radiation mode (Mode 1 mode) and the second radiation mode (Mode 2 mode). When the two semicircular rings of the radiators 210 and 220 form a complete circle, the maximum electric field point and the maximum current point are located at the two ends of the diameter of the circle respectively, and the direction of the electric field current is from the maximum electric field point to the maximum current point. When there are two gaps D between the radiators 210 and 220, due to the capacitance effect brought by the gaps, the position of the maximum electric field point is offset, and the direction of the electric field current between the maximum electric field point and the maximum current point is changed, and finally the equivalent electric field current in Mode 1 mode and Mode 2 mode has a phase difference of 90 degrees, so that the antenna has a circular polarization characteristic. For example, in the GPS L1 frequency band (center frequency 1.58Ghz), the equivalent electric field current distribution of the radiators 210 and 220 in Mode 1 mode and Mode 2 mode is as follows: Figure 3 As shown, the equivalent electric field current distributions are perpendicular to each other, that is, the phase difference is 90 degrees. At the same time, the gap between the radiators 210 and 220 and the floor 30 forms a folded dipole antenna between the radiators 210 and 220 and the floor 30, further making the circularly polarized antenna have omnidirectional characteristics.

[0040] in:

[0041] The size of the gap D is related to the size of the equivalent electric field current component in Mode 2, that is, the equivalent electric field current component in Mode 2 can be changed by adjusting the size of D. For example, in one embodiment of the present application, the gap D can be adjusted within the range of [0.1 mm, 0.3 mm].

[0042] The size of the angle β is related to the impedance matching of the antenna, that is, by adjusting the size of the angle β, the impedance matching of the antenna can be changed. For example, in another embodiment of the present application, the angle β can be adjusted within the range of [30, 60].

[0043] The size of the gap between the radiators 210, 220 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 radiators 210, 220 and the floor 300. For example, in one implementation of the present application, the gap can be adjusted within [2mm, 4mm].

[0044] The width of the circular ring of the radiator 210, 220 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, 220. 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 the GPS bandwidth.

[0045] In one implementation of the present application, the positioning antenna on the wearable electronic device is designed as an omnidirectional right-hand circularly polarized antenna. The right-hand circularly polarized antenna can better receive the right-hand circularly polarized positioning signal emitted by the satellite system. At the same time, the right-hand circularly polarized radiation can also filter the left-hand circularly polarized satellite signal reflected by high-rise buildings or the ground to reduce multipath interference, thereby effectively improving the positioning accuracy of the positioning antenna of the wearable electronic device. In addition, in order to prevent the receiving performance of the right-hand circularly polarized antenna from being affected by the position change of the wearable electronic device, the right-hand circularly polarized antenna also has an omnidirectional property.

[0046] In the implementation of the present application, the floor 300 can be a grounding layer in the motherboard of the wearable electronic device, for example, a reference ground, and the reference ground refers to the GND (Ground) of the circularly polarized antenna 200. As the zero potential plane of the circularly polarized antenna 200, it is usually the copper layer of the motherboard. The "grounding" described in the application is an electrical connection with the reference ground of the motherboard. The grounding terminal is also electrically connected to the radiator 210 at one end, and the other end is connected to the reference ground on the motherboard. It can be understood that the connection between the grounding terminal and the radiator 210 can be an electrical connection formed by a connecting component, or it can be integrally formed, and the present disclosure does not limit this.

[0047] The main board 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 be of other types, such as a combination of a printed circuit board and a flexible printed circuit (FPC), etc., which is not limited in this application.

[0048] For the circularly polarized antenna 200, a feeding module may also be provided in the mainboard, for example, a radio frequency feeding circuit, which may be, for example, a radio frequency integrated circuit (IC) chip. The radio frequency feeding circuit serves as an excitation source of the circularly polarized antenna 200 and is used to feed the radiator 210. One end of the feeding terminal 230 is electrically connected to the radiator 210, and the other end is connected to the radio frequency feeding circuit on the mainboard. It is understandable that the connection between the feeding terminal 230 and the radiator 210 may be an electrical connection formed by a connecting component, or may be integrally formed, and this application does not limit this. In one example, the feeding terminal 230 is integrally formed with the radiator 210, and its free end may be directly electrically connected to the radio frequency feeding circuit of the mainboard 300. As an alternative, its free end may also be electrically connected to the radio frequency feeding circuit of the mainboard 300 through a connector (e.g., a spring structure) on the mainboard 300.

[0049] In the case where a tuning device is required for a circularly polarized antenna, in one implementation of the present application, a radiator (eg, Figure 2-a The radiator 210 in the circular polarization antenna 200 also has a grounding point, and the radiator 210 is electrically connected to the tuning device through the grounding terminal at the grounding point and then connected to the floor 300. The tuning device can be, for example, an inductor or a capacitor. The target operating frequency of the circular polarization antenna 200 is the GPS L1 frequency band (center frequency 1.575 GHz).

[0050] 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 The ground terminal 240 is connected to the ground plane 300 through a capacitor. Since the capacitor can flow displacement current and lengthen the current path, 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.

[0051] 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 floor 300 through the inductor, and the inductor will offset this characteristic of the capacitor and have the opposite effect. 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.

[0052] The present application does not limit the positions of the feeding point B and the grounding point A on the radiator 210 (or on the radiator 220) and the distance between them. In one implementation of the present application, the feeding point B and the grounding point A may be the same point on the radiator 210. That is, Figure 2-b Point B in the figure serves as both a feeding point and a grounding point. Accordingly, the feeding terminal 230 and the grounding terminal are the same terminal and are electrically connected to the RF feeding circuit and the grounding layer (i.e., the reference ground) on the mainboard 300 through a tuning device (e.g., an inductor or a capacitor). Figure 2-c The feeding terminal is electrically connected to the RF feeding circuit (not shown in the figure) on the mainboard 300 through the capacitor C1.

[0053] In an implementation of the present application, the feeding point and the grounding point may be the same point, and the feeding terminal and the grounding terminal may also be the same terminal.

[0054] Finally, it should be noted that Figure 2-a and Figure 2-bIt is only an example. The radiators 210 and 220 in the present application are ring-shaped with openings. However, the embodiment of the present application does not specifically limit the shape of the radiators 210 and 220 and the gap between them. They can be any of the following shapes: circular ring, elliptical ring, quadrilateral, polygonal. Moreover, the embodiment of the present application does not limit the circumferential length of the openings of the radiators 210 and 220. The circumferential length of the openings can be greater than the circumferential length of the radiator 210 or 220, or less than the circumferential length of the radiator 210 or 220, or equal to the circumferential length of the radiator 210 or 220. For example, Figure 2-b The radiator 210 and the radiator 220 shown in the figure are both semicircular, and the circumferential lengths of the radiators are equal. The present application does not limit the circumferential lengths of the two radiators 210 and 220, for example, the circumferential lengths of the two radiators are the same, or the circumferential lengths of the two radiators are different, one radiator has a larger circumferential length, and the other radiator has a smaller circumferential length, but the two radiators with different circumferential lengths and the gap between them can form any of the following shapes: a circular ring, an elliptical ring, a quadrilateral, and a polygonal shape.

[0055] It can be understood that, when the shapes and circumferential lengths of the two radiators 210 and 220 are the same, the two radiators can form a symmetrical arrangement, such as Figure 2-a and Figure 2-b In addition, the embodiment of the present application does not specifically limit the outer contour shape of the mainboard 300, and it can be any one of the following shapes: circular, elliptical, quadrilateral, polygonal.

[0056] In one implementation of the present application, the projections of the open-loop radiators 210 and 220 on the floor may overlap with the outer contour edge of the floor 300. For example, the open-loop radiators 210 and 220 are quadrilateral shapes with openings, and the outer contour of the floor 300 is a quadrilateral.

[0057] 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 radiators 210 and 220 are circular rings with openings, and the outer contours of the corresponding mainboard and the floor 300 located thereon are circular, or the radiators 10 and 220 are rectangular frame shapes, and the outer contours of the corresponding mainboard and the floor 300 located thereon are rectangular.

[0058] In addition, considering the rationality of space design, the center of the shape formed by the radiator 210 , the radiator 220 and the gap therebetween overlaps with the center of the main board and the floor 300 located thereon.

[0059] The antenna pattern is a graph that characterizes the relationship between the antenna's radiation characteristics and the spatial angle. The antenna pattern is also called the far-field pattern. The complete pattern is a three-dimensional spatial graph, which is drawn by measuring the radiation characteristics point by point on a spherical surface with a radius r large enough, with the antenna phase center as the sphere center. For example, by measuring the field strength amplitude, the field strength pattern can be obtained, such as Figure 4 In practice, the directional patterns of the horizontal and vertical planes are usually measured, and the direction Figure 1 They are generally normalized. For example, in the horizontal and vertical planes, the polar coordinates are It represents the field strength value in any direction, and Emax represents the field strength value in the direction of maximum radiation.

[0060] Figure 5 Shows Figure 2-a and Figure 2-b The curve of S11 changing with frequency of the circularly polarized antenna 200 shown in FIG. Figure 6 Shows Figure 2-a and Figure 2-b The curves showing the variation of the axial ratio with frequency at two cross-sectional positions in the spherical radiation pattern of the circularly polarized antenna 200 are shown in FIG. Figure 7-a and Figure 7-b Shows Figure 2-a and Figure 2-b The shown diagram is a spatial simulation diagram of the antenna gain corresponding to the circularly polarized antenna 200 when radiating omnidirectionally.

[0061] 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, and is 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 infinite at this time. 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 5 The change curve shown is Figure 5 The light-colored curve (the curve at the bottom) is the curve of total efficiency, and the dark-colored curve (the curve at the top) is the curve of radiation efficiency, where total efficiency = radiation efficiency - return loss. In the GPS L1 frequency band (center frequency 1.575 GHz), Figure 5 As shown in the total efficiency data at the positions marked by the middle triangles 1, 2 and 3, S11 almost reaches a peak value near the center frequency of 1.575 GHz, indicating that the return loss is very small, and the total efficiency of the circularly polarized antenna 200 is close to the radiation efficiency. It also shows that the circularly polarized antenna 200 has a good impedance bandwidth in the GPSL1 frequency band.

[0062] Arrow Rate (AR) 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 6 The curves showing the change of the axial ratio of the two cross-sectional positions in the spherical radiation pattern with frequency are shown, where: Figure 6 The light-medium curve (the one at the bottom) is θ=45 degrees. The curve of the change of the axis ratio with frequency at the cross-sectional position, the dark curve (the curve located on the top) θ = 45 degrees,

[0063] The curve of the axis ratio changing with frequency at the cross-sectional position. For θ = 45 degrees, At the cross-sectional position, in the GPS L1 frequency band (center frequency 1.575 GHz), Figure 6 As shown in the axial ratio data at the positions marked with the triangle marks 1, 2 and 3 in the middle, the requirement of an axial ratio of less than 3dB in a wider frequency band (1.45-1.75Ghz band) is achieved (here an axial ratio of less than 3dB is taken as a manifestation of a circularly polarized antenna with good circular polarization characteristics), the 3dB axial ratio bandwidth is 18.8%, and the axial ratio reaches its lowest point of 1.066179dB at a frequency of 1.58HZ, which has good circular polarization characteristics.

[0064] Gain is another important parameter that characterizes antenna performance. It is used to measure the antenna's ability to send and receive signals in a specific direction. Specifically, it refers to the ratio of the power density of the signal generated by the actual antenna and the ideal radiating unit at the same point in space under the condition of equal input power. It is usually expressed in dBi. Therefore, gain can quantitatively describe the degree to which the antenna radiates the input power in a concentrated manner in space. Figure 7-a The spatial simulation diagram of the antenna gain corresponding to the right-hand circularly polarized antenna when radiating omnidirectionally is shown, as Figure 7-aAs shown, it has good gain when omnidirectionally radiating, and the gain of the right-hand circularly polarized antenna when omnidirectionally radiating is 1.718dBi; Figure 7-b The spatial simulation diagram of the antenna gain corresponding to the left-hand circularly polarized antenna when radiating omnidirectionally is shown, as Figure 7-b As shown, they both have good gain in omnidirectional radiation, and the gain of the left-hand circularly polarized antenna in omnidirectional radiation is -8.3dBi, that is, the gain of the omnidirectional right-hand circularly polarized antenna is 10dBi greater than that of the omnidirectional left-hand circularly polarized antenna, that is, the cross-polarization ratio is as high as 10dB. The larger the cross-polarization ratio, the stronger the orthogonality of the left-hand and right-hand circularly polarized signals that can be obtained from the antenna, the smaller the correlation between the two signals, and the better the polarization effect finally achieved.

[0065] In the embodiment of the present application, the principle of odd-even mode excitation and mutual coupling effect between adjacent radiators is utilized, and the right-hand circular polarization characteristic of the antenna is realized in an omnidirectional manner through the simple structure of two adjacent open-loop radiators. The 3dB axial ratio bandwidth is as wide as 18.8% (1.45-1.75Ghz), which can greatly enhance the wearable electronic device's ability to receive satellite signals, significantly improve the positioning accuracy and anti-interference ability of the wearable device, and has a strong engineering application value.

[0066] 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 a wearable electronic device, comprising: two open-loop radiators and a floor, wherein the two open-loop radiators are symmetrically arranged, and the openings of the two open-loop radiators are arranged opposite to each other, and the openings of the two open-loop radiators form two gaps between each other; any one of the two open-loop radiators has a feeding point and a grounding point, a feeding signal is connected to the feeding point through a feeding terminal, and the grounding point is connected to the floor through a grounding terminal.

2. The circularly polarized antenna according to claim 1, characterized in that: The two open-ring radiators and the two gaps between the two open-ring radiators form one of the following shapes: a circular ring, an elliptical ring, or a polygonal frame.

3. The circularly polarized antenna according to claim 1, characterized in that: The gap between the two open-loop radiators ranges from [0.1 mm, 0.3 mm].

4. The circularly polarized antenna according to claim 1, characterized in that: The angle between the line connecting the middle points of the two slots and the feeding point and the center line of symmetry of the two open-loop radiators is in the range of [30°, 60°].

5. The circularly polarized antenna according to claim 1, characterized in that: The projections of the two open-loop radiators on the floor overlap with the outer contour edge of the floor.

6. The circularly polarized antenna according to claim 1, characterized in that: The feeding point and the grounding point are the same point, and the feeding terminal and the grounding terminal are the same terminal.

7. The circularly polarized antenna according to claim 1, characterized in that: The center of the shape formed by the two open-loop radiators and the gap between the two open-loop radiators overlaps with the center of the floor.

8. The circularly polarized antenna according to claim 1, 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: It comprises the circularly polarized antenna as claimed in any one of claims 1 to 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.

Images