Inverted-F antenna and wearable device

Abstract

The invention provides an inverted-F antenna and wearable equipment, and relates to the technical field of antennas. The inverted-F antenna comprises an inverted-F antenna body and a metamaterial array, the inverted-F antenna body comprises a radiator, and the radiator transmits electromagnetic waves to a target radiation direction; and the metamaterial array is arranged on one side, deviating from the target radiation direction, of the radiator so as to suppress the reverse radiation of the inverted-F antenna. According to the invention, the metamaterial array used for suppressing the reverse radiation of the inverted-F antenna is arranged on the side, deviating from the target radiation direction, of the radiator of the inverted-F antenna body, so that the directional focusing of the main beam of the inverted-F antenna is realized, the reverse radiation is suppressed, the SAR of the wearable device comprising the inverted-F antenna is reduced, the electromagnetic radiation exposure of a user is reduced, and the user experience is improved. And the use safety of the wearable equipment is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, and in particular to an inverted-F antenna and a wearable device. BACKGROUND

[0002] As the core device of next-generation human-computer interaction, wearable devices such as augmented reality (AR) and virtual reality (VR) are driving revolutionary development in the fields of consumer electronics, medical diagnosis, and industrial maintenance. As a core component for wireless communication in wearable devices, the design of an antenna directly affects the communication stability, power consumption, endurance, volume, and user safety of a wearable device.

[0003] Currently, antennas in wearable devices usually use traditional inverted-F antennas (IFA) for wireless communication. Due to the advantages of simple structure, high miniaturization level, and easy integration, this type of antenna is suitable for the compact space requirements of wearable devices.

[0004] However, the traditional inverted-F antenna in wearable devices has significant back radiation when it is close to a human body model. This back radiation can cause the specific absorption rate (SAR) of the wearable device to increase, thereby reducing the use safety of the wearable device. SUMMARY

[0005] The present application provides an inverted-F antenna and a wearable device to solve the problem that the traditional inverted-F antenna in the related art has significant back radiation when it is close to a human body model, which can cause the specific absorption rate (SAR) of the wearable device to increase, thereby reducing the use safety of the wearable device.

[0006] In a first aspect, the present application provides an inverted-F antenna system, comprising: an inverted-F antenna body and a metamaterial array, wherein the inverted-F antenna body comprises a radiator that transmits electromagnetic waves in a target radiation direction; and the metamaterial array is arranged on the side of the radiator away from the target radiation direction to suppress the back radiation of the inverted-F antenna.

[0007] In a possible implementation, the metamaterial array comprises a plurality of periodically arranged metamaterial units, which are used to regulate the electromagnetic radiation direction of the inverted-F antenna body.

[0008] In a possible implementation, the metamaterial units support a wideband electromagnetic response within a target frequency band, and the target frequency band is between 5 GHz and 7.2 GHz.

[0009] In one possible implementation, the metamaterial unit satisfies a target planar dimension that is adapted to the spatial layout of the wearable device.

[0010] In one possible implementation, the inverted-F antenna further includes: a substrate and a ground plane; a metamaterial array and a radiator are integrated on the same side surface of the substrate, and the ground plane is integrated on the other side surface of the substrate.

[0011] In one possible implementation, the input impedance of the inverted-F antenna body is matched to the output impedance of the wearable device, which is determined based on the geometric parameters of the inverted-F antenna body, including radiator structural parameters.

[0012] In one possible implementation, the length of the inverted-F antenna meets a preset size, which is adapted to the spatial layout of the wearable device.

[0013] Secondly, this application provides a wearable device, including: a wearable device body and an inverted F antenna as provided in the first aspect above.

[0014] In one possible implementation, the wearable device includes wearable glasses, with the inverted-F antenna integrated within the back cover of the temples of the wearable glasses.

[0015] In one possible implementation, the temple back cover includes a temple back plate, an inverted F antenna is embedded in the temple back plate, and the temple back plate is located on the side of the temple away from the human body.

[0016] This application provides an inverted-F antenna and a wearable device. The inverted-F antenna includes an inverted-F antenna body and a metamaterial array. The inverted-F antenna body includes a radiator that transmits electromagnetic waves in the target radiation direction. The metamaterial array is disposed on the side of the radiator away from the target radiation direction to suppress the back radiation of the inverted-F antenna. This application, by disposing of a metamaterial array on the side of the radiator of the inverted-F antenna body away from the target radiation direction to suppress back radiation, achieves directional focusing of the main beam of the inverted-F antenna and suppresses back radiation, thereby reducing the SAR of the wearable device containing the inverted-F antenna, reducing the user's electromagnetic radiation exposure, and improving the safety of using the wearable device. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] Figure 1 This is a schematic diagram of the structure of the inverted-F antenna provided in an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the structure of the inverted-F antenna body provided in the embodiments of this application;

[0020] Figure 3 This is a schematic diagram of the performance curve of the inverted-F antenna body provided in the embodiments of this application;

[0021] Figure 4 This is a schematic diagram of the performance curves of the inverted-F antenna provided in an embodiment of this application;

[0022] Figure 5 A schematic diagram of the radiation direction of the inverted-F antenna body provided in an embodiment of this application;

[0023] Figure 6 A schematic diagram of the radiation direction of the inverted-F antenna provided in an embodiment of this application;

[0024] Figure 7 This is a schematic diagram comparing the performance curves of the inverted-F antenna body and the inverted-F antenna provided in the embodiments of this application;

[0025] Figure 8 A schematic diagram illustrating the integration of the inverted-F antenna body into the head phantom, provided for an embodiment of this application;

[0026] Figure 9 A schematic diagram of the performance curve of the inverted-F antenna body integrated with the head phantom provided in the embodiments of this application;

[0027] Figure 10 A schematic diagram of the performance curve of the inverted-F antenna integrated with the head phantom provided in an embodiment of this application;

[0028] Figure 11 A schematic diagram of the radiation direction of the inverted-F antenna body integrated with the head phantom provided in an embodiment of this application;

[0029] Figure 12 A schematic diagram of the radiation direction of the inverted-F antenna integrated with the head phantom provided in an embodiment of this application;

[0030] Figure 13 This is a SAR schematic diagram of the inverted-F antenna body provided in an embodiment of this application;

[0031] Figure 14 This is a schematic diagram of an inverted-F antenna provided in an embodiment of this application for SAR purposes.

[0032] Figure 15 This is a schematic diagram of the structure of the metamaterial unit provided in the embodiments of this application;

[0033] Figure 16 This is a schematic diagram of the performance curves of the metamaterial unit provided in the embodiments of this application;

[0034] Figure 17 This is a schematic diagram of the performance curves of the metamaterial array provided in the embodiments of this application.

[0035] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0036] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0037] With the rapid development of AR and VR technologies, wearable AR or VR devices place increasingly higher demands on antenna systems, requiring a focus on both high performance and user safety. Currently, one of the key challenges facing traditional inverted-F antenna systems in wearable AR or VR devices is the management of electromagnetic radiation exposure.

[0038] Currently, wearable AR devices, such as wearable AR glasses, not only need to achieve high-resolution displays and low-latency interactions, but also need to support high-speed wireless communication (such as Wi-Fi 6E / 7, 5G millimeter wave) to meet the requirements of real-time data transmission and cloud rendering. However, the compact structure of wearable AR glasses (typically with a temple back plate thickness of...) The miniaturization of antennas (in millimeters) presents a significant challenge to antenna design, requiring strict control over the safety impact of electromagnetic radiation on the human body while ensuring multi-band broadband performance. According to a report by the International Telecommunication Union (ITU), a relatively high percentage of wearable AR devices have failed electromagnetic compatibility (EMC) certification due to substandard antenna performance. This phenomenon highlights the core bottlenecks in miniaturization and safety compliance of existing antenna technology.

[0039] In the design of antennas for wearable AR glasses, the trade-off between SAR (Specific Absorption Regulator) and radiation efficiency is particularly prominent. While traditional inverted-F antennas can achieve broadband coverage in the 5GHz-7GHz frequency band, their near-field radiation can cause local SAR values ​​on the head to exceed the specified limit of 1.6 W / kg. Studies have shown that when the distance between a traditional inverted-F antenna and human tissue... When the thickness reaches millimeters, the energy absorption efficiency of electromagnetic waves increases by 80%. Therefore, there is an urgent need to propose a new antenna architecture to simultaneously optimize radiation characteristics and safety indicators within an ultra-thin space.

[0040] Based on the problems existing in related technologies, this application embodiment sets up a metamaterial array on the side of the radiator of the inverted F antenna body away from the target radiation direction to suppress the reverse radiation of the inverted F antenna. This enables directional focusing of the main beam of the inverted F antenna and suppresses the reverse radiation, thereby reducing the SAR of the wearable device containing the inverted F antenna, reducing the user's electromagnetic radiation exposure, and improving the safety of the wearable device.

[0041] The application scenarios of the embodiments of this application will be described in detail below.

[0042] The inverted-F antenna provided in this application embodiment is suitable for wireless communication modules of wearable AR devices or wearable VR devices, especially for scenarios such as industrial inspection, medical assistance, and consumer electronics where there is a need for high bandwidth, low latency, and human safety.

[0043] The inverted-F antenna provided in this application will be described in detail below with reference to specific embodiments.

[0044] Figure 1 This is a schematic diagram of the structure of the inverted-F antenna provided in an embodiment of this application. Figure 1 As shown, the inverted-F antenna includes an inverted-F antenna body 11 and a metamaterial array 12. The inverted-F antenna body 11 includes a radiator 13, which transmits electromagnetic waves in the direction of radiation toward the target.

[0045] The metamaterial array is positioned on the side of the radiator away from the target radiation direction to suppress the reverse radiation of the inverted-F antenna.

[0046] like Figure 1 As shown, the metamaterial array 12 comprises three periodically arranged metamaterial units, meaning that the metamaterial array 12 can be... Arrays (such as) Figure 1 (As shown in the dashed box 14). Each metamaterial unit adopts a multi-layered nested box structure. This application embodiment does not limit the number of metamaterial units in the metamaterial array 12, nor the periodic arrangement of the metamaterial array; it can be determined according to the actual application requirements.

[0047] For example, each metamaterial unit in the metamaterial array 12 may adopt an open resonant ring-type metamaterial structure, in which a nested arrangement of multiple layers of metal or conductive materials is used.

[0048] It is understood that the metamaterial array provided in this application embodiment, by adopting a multi-layer nested structure, absorbs electromagnetic waves in a specific direction (such as reverse radiation toward the human body) based on the electromagnetic resonance effect of the multi-layer nested structure, thereby achieving electromagnetic radiation modulation of the inverted F antenna and suppressing the reverse radiation of the inverted F antenna.

[0049] For example, the reverse radiation of an inverted-F antenna refers to the radiation component of the electromagnetic waves radiated by the inverted-F antenna that is directed towards a non-target radiation direction (such as the direction pointing towards the human body). In wearable AR glasses, for instance, the target radiation direction could be external space away from the wearer's head, used for communication; the reverse radiation is the radiation directed towards the wearer's head. Understandably, reverse radiation can lead to electromagnetic exposure.

[0050] like Figure 1 As shown, a feed point is provided on the radiator 13, which serves as the connection interface between the radiator and an external signal source (the communication module of the wearable device in the figure). For example, the radiator receives the input electrical signal through the feed point, converts the electrical signal into an alternating current based on its own conductivity characteristics, and then forms an alternating electromagnetic field through cooperation with the ground plane, ultimately radiating electromagnetic waves outward, such as radiating electromagnetic waves in the direction of the target radiation.

[0051] Figure 2 This is a schematic diagram of the structure of the inverted-F antenna body provided in an embodiment of this application. Figure 2 As shown, the inverted-F antenna body includes a radiator, a feed point, and a short-circuit structure (such as a grounded short-circuit pin or arm). The main radiating arm of the radiator can be 21.55 mm long, which determines the fundamental resonant frequency of the inverted-F antenna body, adapting to the 5 GHz - 7.2 GHz wide operating frequency band. The dimensions of the area containing the feed point and short-circuit structure can be 11.55 mm to adjust the impedance characteristics of the inverted-F antenna, ensuring that the input impedance of the inverted-F antenna body matches the output impedance of the wearable device.

[0052] The following is a combination of... Figure 3 and Figure 4 The performance of the inverted-F antenna body and the inverted-F antenna provided in the embodiments of this application are illustrated by examples.

[0053] Figure 3 This is a schematic diagram of the performance curves of the inverted-F antenna body provided in an embodiment of this application. Figure 3 In the middle, 3a represents the S of the inverted F antenna body. 11 A parameter curve diagram, where the horizontal axis represents frequency (GHz) and the vertical axis represents decibels (dB), as shown below. Figure 3 Figure 3b shows a schematic diagram of the radiation efficiency curve of the inverted-F antenna body, where the horizontal axis represents frequency (GHz) and the vertical axis represents decibels (dB). S 11The parameter curves are used to characterize the impedance matching characteristics of the inverted-F antenna body.

[0054] like Figure 3 As shown in Figure 3a, simulation results of the inverted-F antenna body show that, under the criterion of -6.72 dB, the resonant bandwidth of the inverted-F antenna body covers 5.02 GHz-7.3 GHz, effectively covering the wide operating frequency bands suitable for wearable devices, such as the 5G band and the Wi-Fi 6E band. As shown in Figure 3b, the radiation efficiency curve of the inverted-F antenna body shows that the radiation efficiency values ​​of the inverted-F antenna body at 5.51 GHz and 6.85 GHz are -0.3 dB and -0.015 dB, respectively. After conversion, the corresponding radiation efficiency for the 5G band and the Wi-Fi 6E band is approximately 98%. These simulation results demonstrate that the inverted-F antenna has high radiation performance within the wide operating frequency bands (5G band and Wi-Fi 6E band) suitable for wearable devices.

[0055] Figure 4 This is a schematic diagram of the performance curves of the inverted-F antenna provided in an embodiment of this application. Figure 4 In the middle, 4a represents the S of the inverted F antenna. 11 A parameter curve diagram, where the horizontal axis represents frequency (GHz) and the vertical axis represents decibels (dB), as shown below. Figure 4 Figure 4b shows a schematic diagram of the radiation efficiency curve of the inverted-F antenna, where the horizontal axis represents frequency (GHz) and the vertical axis represents decibels (dB).

[0056] like Figure 4 As shown in Figure 4a, simulation results of the inverted-F antenna demonstrate that it achieves dual-band resonance in the 6.02GHz and 7.23GHz frequency bands, covering wide operating frequency bands suitable for wearable devices, such as the 5G band and the Wi-Fi 6E band. Figure 4 As shown in 4b, although in such Figure 2 The inverted-F antenna shown integrates a metamaterial array on its main body, but it still maintains high radiation efficiency across the entire operating wideband, including 5.51 GHz, 5.66 GHz, 6.01 GHz and 7.23 GHz, to ensure its reliable performance in practical applications.

[0057] In combination with the above Figure 3 and Figure 4 Analysis of the results shows that the inverted-F antenna provided in this application embodiment can effectively balance directional gain and reverse radiation suppression effect, and is suitable for wearable devices such as smartwatches, AR headsets or VR headsets that need to be in close contact with the human body.

[0058] The following is combined with Figure 5 and Figure 6The radiation pattern characteristics of the inverted-F antenna body and the inverted-F antenna provided in the embodiments of this application are illustrated by examples.

[0059] Figure 5 This is a schematic diagram illustrating the radiation direction of the inverted-F antenna body provided in an embodiment of this application. Figure 5 Figure 5a shows a schematic diagram of the far-field simulation results of the inverted-F antenna body at an operating frequency of 5.51 GHz. Figure 5 Figure 5b shows a schematic diagram of the far-field simulation results of the inverted-F antenna body at a working frequency of 7 GHz. Here, Rad. Effic. represents the radiation efficiency, which is the proportion of input energy converted into electromagnetic radiation by the inverted-F antenna body; Tot. Effic. represents the total efficiency, which is the product of the radiation efficiency and the impedance matching efficiency, used to represent the proportion of energy actually effectively radiated by the inverted-F antenna body; and Gain represents the gain, which is the multiple of the radiation intensity of the inverted-F antenna body in a certain direction compared to an omnidirectional antenna.

[0060] like Figure 5 As shown in Figure 5a, at an operating frequency of 5.51 GHz, the radiation efficiency of the inverted-F antenna body is 1.006, the overall efficiency is 0.9212, and the gain is 2.040 dB; Figure 5 As shown in Figure 5b, at a working frequency of 7 GHz, the radiation efficiency of the inverted-F antenna body is 0.9904, the overall efficiency is 0.9839, and the gain is 2.176 dB. Figure 5 As shown, the radiation patterns of the inverted-F antenna at operating frequencies of 5.51 GHz and 7 GHz both demonstrate that the antenna exhibits predominantly omnidirectional radiation characteristics, with the radiation intensity showing a slight variation with the color gradient scale. This stable radiation performance, combined with... Figure 3 The broadband operating characteristics and high radiation efficiency shown demonstrate that the inverted-F antenna exhibits excellent structural stability, impedance matching capability, radiation efficiency, and directional performance across the entire operating bandwidth. This makes it suitable for various wireless communication applications, particularly 5G and Wi-Fi 6E systems where stable omnidirectional coverage is a core requirement. The synergistic effect of these electrical and radiation characteristics makes this inverted-F antenna (IFA) design especially suitable for modern compact wireless devices requiring reliable multi-band operation.

[0061] Figure 6 This is a schematic diagram illustrating the radiation direction of the inverted-F antenna provided in an embodiment of this application. Figure 6 Figure 6a shows a schematic diagram of the far-field simulation results of the inverted-F antenna at an operating frequency of 5.51 GHz. Figure 5 Figure 5b shows a schematic diagram of the far-field simulation results at the 7GHz operating frequency of the inverted-F antenna.

[0062] like Figure 6As shown in Figure 6a, at an operating frequency of 5.51 GHz, the inverted-F antenna has a radiation efficiency of 0.9987, a total efficiency of 0.9353, and a gain of 1.910 dB; Figure 6 As shown in Figure 6b, at a working frequency of 7 GHz, the inverted-F antenna has a radiation efficiency of 0.9774, a total efficiency of 0.6941, and a gain of 3.411 dB. Combined with... Figure 5 and Figure 6 As shown in the simulation structure, both the inverted-F antenna body and the inverted-F antenna integrated with the metamaterial array provided in this application embodiment maintain stable radiation patterns across the entire operating bandwidth. The integration of the metamaterial array significantly improves the field focusing effect of the inverted-F antenna at higher frequencies and reduces pattern distortion. Comprehensive radiation characteristic analysis indicates that the inverted-F antennas provided in this application embodiment are suitable for wireless communication applications and achieve comprehensive performance enhancement while maintaining a compact size.

[0063] In combination with the above Figure 3 to Figure 6 The simulation analysis results show that the inverted-F antenna provided in this application embodiment exhibits superior radiation characteristics at frequencies of 5.51GHz, 5.66GHz, 6.82GHz and 6.844GHz. Its detailed performance parameters are as follows: total efficiency exceeds 0.9, radiation efficiency is higher than 0.95, and gain is approximately 2dB.

[0064] Figure 7 This is a schematic diagram comparing the performance curves of the inverted-F antenna body and the inverted-F antenna provided in the embodiments of this application. Figure 7 7a represents the S-axis of the inverted-F antenna body and the inverted-F antenna. 11 A diagram comparing parameter curves, where curve 71 represents the S corresponding to the inverted F antenna body. 11 Parameter curves, curve 72 represents the S corresponding to the inverted F antenna. 11 The parameter curve has the horizontal axis representing frequency (GHz) and the vertical axis representing decibels (dB); for example... Figure 7 Figure 7b shows a schematic diagram comparing the radiation efficiency curves of the inverted-F antenna body and the inverted-F antenna. Curve 73 represents the radiation efficiency curve corresponding to the inverted-F antenna body, and curve 74 represents the radiation efficiency curve corresponding to the inverted-F antenna. The horizontal axis represents frequency (GHz), and the vertical axis represents decibels (dB).

[0065] from Figure 7As shown in Figure 7a, point 4 of curve 71 indicates an operating frequency of 5.00 GHz at -6.49 dB; point 5 of curve 71 indicates an operating frequency of 6.87 GHz at -33.03 dB; point 1 of curve 72 indicates an operating frequency of 5.02 GHz at -5.87 dB; point 2 of curve 72 indicates an operating frequency of 5.99 GHz at -20.22 dB; and point 3 of curve 72 indicates an operating frequency of 7.21 GHz at -7.28 dB. Based on the above simulation results, it can be seen that compared to the inverted-F antenna integrated with a metamaterial array, the operating bandwidth of the inverted-F antenna itself is limited, while the metamaterial array can improve the operating bandwidth of the inverted-F antenna.

[0066] from Figure 7 As shown in Figure 7b, point 5 of curve 73 indicates an operating frequency of 5.51 GHz at -0.36 dB; point 6 indicates an operating frequency of 6.84 GHz at -0.01 dB; point 1 of curve 74 indicates an operating frequency of 5.51 GHz at -0.29 dB; point 2 indicates an operating frequency of 7.23 GHz at -0.94 dB; point 3 indicates an operating frequency of 5.66 GHz at -0.199 dB; and point 4 indicates an operating frequency of 6.01 GHz at -0.05 dB. Based on the above simulation results, it can be seen that the inverted-F antenna with integrated metamaterial array, compared to the inverted-F antenna itself, exhibits a deeper resonance effect across the entire operating bandwidth, optimized impedance matching performance, and significantly enhanced radiation efficiency.

[0067] The following is combined with Figure 8 to Figure 14 The SAR compliance of the inverted-F antenna provided in the embodiments of this application is explained.

[0068] Figure 8 This is a schematic diagram illustrating the integration of the inverted-F antenna body into the head phantom, as provided in an embodiment of this application. Figure 8 As shown, the inverted F antenna body 82 is arranged on the head phantom 81.

[0069] Figure 9 This is a schematic diagram showing the performance curves of the inverted-F antenna body integrated with the head phantom, as provided in an embodiment of this application. Figure 9 9a represents the S-shaped inverted-F antenna body integrated with the head phantom. 11 A parameter curve diagram, where the horizontal axis represents frequency (GHz) and the vertical axis represents decibels (dB), as shown below. Figure 9 Figure 9b shows a schematic diagram of the radiation efficiency curve of the inverted-F antenna body integrated with the head phantom, where the horizontal axis is frequency (GHz) and the vertical axis is decibel (dB).

[0070] from Figure 9 As can be seen from Figure 9a, when the inverted-F antenna body is integrated onto the head phantom, its inverted-F antenna body can still achieve a relatively wide operating bandwidth of 5GHz-7.4GHz. However, by comparing the above... Figure 3 The radiation efficiency curve of the inverted-F antenna body shown in Figure 3b is similar to... Figure 9 As shown in Figure 9b, the radiation efficiency curve of the inverted-F antenna integrated with the head phantom shows that when the inverted-F antenna is placed on the head phantom, its radiation efficiency decreases. The specific reasons are as follows: When the inverted-F antenna is simulated in free space, it usually exhibits high radiation efficiency due to the absorption or interference of the nearby lossless medium. However, when placed on the head phantom, the radiation efficiency will decrease significantly due to various factors, such as the conductivity and dielectric properties of the head tissue absorbing some of the radiation energy, thereby reducing the overall radiation efficiency.

[0071] Figure 10 This is a schematic diagram showing the performance curves of the inverted-F antenna integrated with the head phantom, provided as an embodiment of this application. Figure 10 10a in the middle represents the S-shaped inverted F antenna integrated with the head phantom. 11 A parameter curve diagram, where the horizontal axis represents frequency (GHz) and the vertical axis represents decibels (dB), as shown below. Figure 10 In Figure 10b, curve 101 represents the radiation efficiency curve of the inverted-F antenna integrated with the head phantom, and curve 102 represents the overall efficiency curve of the inverted-F antenna integrated with the head phantom. The horizontal axis represents frequency (GHz), and the vertical axis represents decibels (dB).

[0072] from Figure 10 As can be seen from 10a, the inverted-F antenna provided in this application embodiment has relatively stable impedance characteristics when working near human tissue.

[0073] By comparison Figure 10 The radiation efficiency curve of the inverted-F antenna integrated with the head phantom, shown in curve 101 of section 10b, is as follows. Figure 3 The radiation efficiency curve of the inverted-F antenna body shown in Figure 3b, Figure 4 The radiation efficiency curve of the inverted-F antenna shown in Figure 4b, and Figure 9 As shown in Figure 9b, the radiation efficiency curve of the inverted-F antenna body integrated with the head phantom shows that the inverted-F antenna with a metamaterial array integrated on the inverted-F antenna body provided in this application embodiment can reduce efficiency loss and improve the radiation efficiency of the inverted-F antenna when working near human tissue.

[0074] By comparison Figure 9 and Figure 10The results show that the head phantom alters the near-field distribution of the antenna, degrading the impedance matching performance of the inverted-F antenna body, thereby increasing the reflection loss and causing detuning. Simultaneously, the presence of the head phantom introduces surface waves and scattering effects, further causing energy to deviate from the effective radiation path. However, by integrating the metamaterial array provided in this application embodiment onto the inverted-F antenna body, the performance of the inverted-F antenna can be improved and energy loss reduced.

[0075] Figure 11 This is a schematic diagram illustrating the radiation direction of the inverted-F antenna body integrated with the head phantom, as provided in an embodiment of this application. Figure 11 Figure 11a shows a schematic diagram of the far-field simulation results of the inverted-F antenna body integrated with the head phantom at an operating frequency of 5.51 GHz. Figure 11 Figure 11b shows a schematic diagram of the far-field simulation results of the inverted-F antenna body integrated with the head phantom at a working frequency of 7 GHz.

[0076] like Figure 11 As shown in Figure 11a, at an operating frequency of 5.51 GHz, the radiation efficiency of the inverted-F antenna integrated with the head phantom is 0.5552, the overall efficiency is 0.5039, and the gain is 3.586 dB; Figure 11 As shown in Figure 11b, at a working frequency of 7 GHz, the radiation efficiency of the inverted-F antenna integrated with the head phantom is 0.6947, the overall efficiency is 0.6854, and the gain is 4.482 dB. This is compared to... Figure 11 and Figure 5 The results show that the radiation efficiency of the inverted-F antenna integrated with the head phantom is significantly reduced compared to the standalone inverted-F antenna. Understandably, although the inverted-F antenna integrated with the head phantom can successfully radiate electromagnetic waves outwards from the head, there is measurable reverse radiation, which may lead to an increase in the SAR value.

[0077] Figure 12 This is a schematic diagram illustrating the radiation direction of the inverted-F antenna integrated with the head phantom, provided as an embodiment of this application. Figure 12 Figure 12a shows a schematic diagram of the far-field simulation results of the inverted-F antenna integrated with the head phantom at an operating frequency of 5.51 GHz. Figure 12 Figure 12b shows a schematic diagram of the far-field simulation results of the inverted-F antenna integrated with the head phantom at a working frequency of 7 GHz.

[0078] like Figure 12 As shown in Figure 12a, at an operating frequency of 5.51 GHz, the radiation efficiency of the inverted-F antenna integrated with the head phantom is 0.5779, the overall efficiency is 0.3876, and the gain is 3.554 dB, indicating that the inverted-F antenna still possesses stable radiation characteristics in the presence of human tissue. Figure 12As shown in Figure 12b, at a working frequency of 7 GHz, the inverted-F antenna integrated with the head phantom has a radiation efficiency of 0.6499, a total efficiency of 0.4087, and a gain of 3.681 dB. This inverted-F antenna has better energy utilization efficiency at a working frequency of 7 GHz.

[0079] Figure 13 This is a SAR schematic diagram of the inverted-F antenna body provided in an embodiment of this application. Figure 13 In the diagram, 13a represents the SAR corresponding to a 1g structure at a 5.51GHz operating frequency for the inverted-F antenna body; 13b represents the SAR corresponding to a 10g structure at a 5.51GHz operating frequency for the inverted-F antenna body; 13c represents the SAR corresponding to a 1g structure at a 7GHz operating frequency for the inverted-F antenna body; and 13d represents the SAR corresponding to a 10g structure at a 7GHz operating frequency for the inverted-F antenna body.

[0080] from Figure 13 From section 13a, it can be seen that the SAR of 1g of tissue corresponding to the inverted-F antenna body at an operating frequency of 5.51 GHz is 4.83 W / kg; from Figure 13 From section 13b, it can be seen that the SAR of 10g of tissue corresponding to the inverted-F antenna body at an operating frequency of 5.51 GHz is 1.23 W / kg; from Figure 13 From section 13c, it can be seen that the SAR of 1g of tissue corresponding to the inverted-F antenna body at a working frequency of 7GHz is 2.43W / kg; from Figure 13 As shown in Figure 13d, the SAR of 10g of tissue with the inverted-F antenna body at a 7GHz operating frequency is 0.73W / kg. Compared with the specified safety limit of 1.6 W / kg, the SAR of 1g of tissue with this inverted-F antenna body at both 5.51 GHz and 7GHz operating frequencies is greater than the safety limit of 1.6 W / kg.

[0081] Figure 14 This is a schematic diagram of a SAR using an inverted-F antenna provided in an embodiment of this application. Figure 14 In the diagram, 14a represents the SAR corresponding to a 1g structure with an inverted F antenna operating at a frequency of 5.51 GHz; 14b represents the SAR corresponding to a 10g structure with an inverted F antenna operating at a frequency of 5.51 GHz; 14c represents the SAR corresponding to a 1g structure with an inverted F antenna operating at a frequency of 7 GHz; and 14d represents the SAR corresponding to a 10g structure with an inverted F antenna operating at a frequency of 7 GHz.

[0082] from Figure 14 From section 14a, it can be seen that at an operating frequency of 5.51 GHz, the SAR of 1 g of tissue using the inverted-F antenna is 1.94 W / kg; from Figure 14From section 14b, it can be seen that the SAR of 10g tissue with the inverted-F antenna at an operating frequency of 5.51GHz is 0.71 W / kg; from Figure 14 From section 14c, it can be seen that at a working frequency of 7 GHz, the SAR of 1 g of tissue using the inverted-F antenna is 1.18 W / kg; from Figure 14 As shown in Figure 14d, the SAR of 10g tissue with the inverted-F antenna at a 7GHz operating frequency is 0.33W / kg. Compared to the specified safety limit of 1.6 W / kg, the SAR of 1g tissue with this inverted-F antenna at both 5.51 GHz and 7GHz operating frequencies is greater than the safety limit of 1.6 W / kg.

[0083] By comparison Figure 13 and Figure 14 The SAR distribution results show that energy absorption is mainly concentrated in the surface tissue, and attenuates rapidly in the depth direction inside the head phantom. This distribution characteristic verifies that the inverted-F antenna provided in this embodiment can minimize the risk of electromagnetic radiation exposure while maintaining high-efficiency radiation. The research results confirm that the integration of metamaterial arrays on the inverted-F antenna body achieves dual benefits, namely, improving antenna performance without sacrificing user safety in wearable device applications.

[0084] It is understood that the inverted-F antenna provided in the embodiments of this application provides key design verification for applications in head-worn devices, medical wearable devices, and other near-field wireless systems for the human body that require strict compliance with specific absorption rate requirements.

[0085] In this embodiment, a metamaterial array is provided on the side of the radiator of the inverted-F antenna body away from the target radiation direction to suppress the reverse radiation of the inverted-F antenna. This enables directional focusing of the main beam of the inverted-F antenna and suppresses the reverse radiation, thereby reducing the SAR of the wearable device containing the inverted-F antenna, reducing the user's electromagnetic radiation exposure, and improving the safety of the wearable device.

[0086] Optionally, the metamaterial array includes multiple periodically arranged metamaterial units, which are used to modulate the electromagnetic radiation direction of the inverted-F antenna body.

[0087] Figure 15 This is a schematic diagram of the structure of the metamaterial unit provided in an embodiment of this application. Figure 15 As shown, exemplarily, the size of the metamaterial unit provided in this application embodiment can be... .

[0088] Figure 15 The metamaterial units shown are similar to those described above, and will not be repeated here.

[0089] Figure 16This is a schematic diagram of the performance curves of the metamaterial unit provided in an embodiment of this application. Figure 16 As shown in the figure, curve 161 represents the S of the metamaterial unit. 11 The parameter curve, curve 162, represents the radiation efficiency curve of the metamaterial unit, where the horizontal axis represents frequency (GHz) and the vertical axis represents decibels (dB). For example, point 1 in curve 161 indicates that the operating frequency is 5.15 GHz at -9.98 dB, and point 2 in curve 161 indicates that the operating frequency is 7.2 GHz at -11.09 dB.

[0090] from Figure 16 As can be seen from curve 161, this size is compact. The metamaterial unit exhibits strong absorption peaks, reaching -9.98 dB at 5.15 GHz and 11.09 dB at 7.2 GHz. This metamaterial unit structure enables broadband operation from 5 GHz to 7.2 GHz. This performance makes the metamaterial unit suitable for 5G and Wi-Fi 6E applications in wearable devices. Figure 16 As can be seen from curve 161, this metamaterial unit can achieve an extremely deep resonance of approximately -60 dB at 6 GHz; from Figure 16 As can be seen from curve 162, this metamaterial unit exhibits high radiation efficiency in the operating frequency band from 5.15 GHz to 7.2 GHz.

[0091] The following is combined with Figure 17 Regarding the above Figure 1 The metamaterial array shown in the dashed box 14 is... The performance of the array will be explained.

[0092] Figure 17 This is a schematic diagram of the performance curves of the metamaterial array provided in an embodiment of this application. Figure 17 As shown in the figure, curve 171 represents the S of the metamaterial array. 11 The parameter curves, specifically curve 172, represent the radiation efficiency curves of the metamaterial array. The horizontal axis represents frequency (GHz), and the vertical axis represents decibels (dB). For example, point 1 in curve 171 indicates that at -10.46 dB, the corresponding operating frequency is 4.95 GHz; point 2 in curve 171 indicates that at -10.27 dB, the corresponding operating frequency is 7.13 GHz.

[0093] from Figure 17 Middle curve 171 and Figure 16Analysis of the results of curve 161 shows that the metamaterial array provided in this application embodiment maintains the same frequency band operating characteristics as the metamaterial unit, that is, it can work effectively in the 5GHz - 7.2 GHz frequency band, covering the working broadband frequency band of wearable devices (5G band and Wi-Fi 6E band).

[0094] In this embodiment of the application, the metamaterial array includes multiple periodically arranged metamaterial units, and each metamaterial unit is used to regulate the electromagnetic radiation direction of the inverted F antenna body to suppress the reverse radiation of the inverted F antenna body toward the human body and improve the radiation efficiency.

[0095] Optionally, the metamaterial unit provided in this application embodiment supports broadband electromagnetic response in a target frequency band, which is between 5 GHz and 7.2 GHz.

[0096] This performance can be achieved through Figure 16 The performance curves of the metamaterial units shown herein are illustrated and will not be elaborated upon here.

[0097] It is understood that the operating broadband characteristics of the metamaterial unit provided in this application embodiment can meet the operating broadband frequency band requirements of wearable devices, that is, the inverted-F antenna integrated with the metamaterial array containing the metamaterial unit provided in this application embodiment can be applied to wearable devices.

[0098] Optionally, the metamaterial unit satisfies a target planar dimension that is adapted to the spatial layout of the wearable device.

[0099] For example, the target planar size of the metamaterial unit can be less than or equal to 8mm × 8mm.

[0100] For example, the spatial layout of a wearable device can be limited antenna mounting space for wearable AR glasses, such as the thickness of the temple back plate of the wearable AR glasses being less than 5mm.

[0101] Optionally, the inverted-F antenna provided in this application embodiment further includes a substrate and a ground plane, wherein the metamaterial array and the radiator are integrated on the same side surface of the substrate, and the ground plane is integrated on the other side surface of the substrate.

[0102] For example, the substrate can be made of FR4 (glass fiber epoxy resin) or polyimide film, etc. It is understood that the substrate serves as an insulating substrate in the inverted-F antenna provided in this embodiment of the application, used to support the metamaterial array and conductive structures such as the radiator.

[0103] In this embodiment, the substrate uses standard printed circuit board (PCB) materials (such as FR4 epoxy resin board) and scalable manufacturing processes to reduce mass production costs, making it suitable for mass market promotion and offering high cost-effectiveness and scalability.

[0104] For example, the ground plane can be a conductive metal layer such as copper foil. It is understood that the ground plane serves as the reference ground of the inverted-F antenna provided in this embodiment of the application, forming a resonant circuit with the radiator and short-circuit structure.

[0105] It is understood that the embodiments of this application integrate the metamaterial array and the radiator on the same side surface of the substrate, and integrate the ground plane on the other side surface of the substrate, so as to stably form a resonant electric field or magnetic field, ensuring the wide operating frequency band (such as 5 GHz - 7.2 GHz) of the inverted F antenna. At the same time, by setting the metamaterial array and the radiator on the same side, the electromagnetic radiation direction of the radiator can be directly controlled by the metamaterial array, thereby reducing SAR.

[0106] Optionally, the input impedance of the inverted-F antenna provided in this application embodiment is matched with the output impedance of the wearable device. The input impedance is determined according to the geometric parameters of the inverted-F antenna body, including the radiator structure parameters.

[0107] For example, the structural parameters of the radiator include the length of the main radiating arm, and the dimensional parameters of the areas where the feed point and short-circuit structure are located. The length of the main radiating arm and the dimensional parameters of the areas where the feed point and short-circuit structure are located are similar to those described above and will not be repeated here.

[0108] Optionally, the length of the inverted-F antenna provided in this application embodiment meets a preset size, which is adapted to the spatial layout of the wearable device.

[0109] For example, the preset size can be 24mm. This application does not limit the size of the preset size; it can be determined according to actual application requirements.

[0110] For example, the length of the inverted-F antenna provided in this application embodiment is less than or equal to 24 mm.

[0111] The spatial layout for wearable devices is similar to that described above, and will not be repeated here.

[0112] In summary, the inverted-F antenna provided in this application has the following beneficial effects:

[0113] 1) Compared to related technologies where AR glasses require compact, low-profile antennas that do not compromise the aesthetics and ergonomics of the product, this application's embodiments, through the design of compact metamaterial units and metamaterial arrays, adapt to the limited installation space of wearable AR glasses. This allows for seamless integration without compromising the aesthetics and ergonomics of the wearable AR glasses, effectively solving the space constraints of wearable devices while maintaining effective electromagnetic properties.

[0114] 2) Compared to related technologies where AR or VR applications require high-speed, low-latency connections in the 5G (5.5 GHz-6 GHz) and Wi-Fi 6E (6 GHz-7.2 GHz) bands, traditional inverted-F antennas suffer from bandwidth limitations. The inverted-F antenna provided in this application achieves dual-band resonance in the 6.02 GHz and 7.23 GHz bands, maintaining high radiation efficiency across the entire operating frequency band of 5G (5.5 GHz-6 GHz) and Wi-Fi 6E (6 GHz–7.2 GHz). This provides a reliable low-latency connection for AR or VR applications;

[0115] 3) Compared to the omnidirectional antennas in related technologies that waste energy in non-target radiation directions and reduce the effective gain of AR applications, in the embodiments of this application, the integration of metamaterial arrays can enhance the directivity of the inverted F antenna, so that the radiated energy is focused in the end-fire direction (away from the user's head), and at the same time, improve the signal strength of AR or VR streaming media transmission, real-time cloud computing and low-latency wireless communication.

[0116] 4) Compared to related technologies where antennas placed close to the human head may exceed SAR safety limits and pose health risks to users, in this application's example, the metamaterial array can suppress the reverse radiation of the inverted-F antenna, minimizing the electromagnetic radiation exposure to the user's head (e.g., reverse radiation suppression rate). This caused the SAR value to drop to (10g tissue) effectively reduces user health risks.

[0117] Optionally, embodiments of this application also provide a wearable device, including: a wearable device body and an inverted-F antenna as described in the above embodiments.

[0118] For example, wearable devices can be smart bracelets, AR glasses, and VR glasses.

[0119] Optionally, the wearable device includes wearable glasses, with the inverted-F antenna integrated into the back cover of the temple of the wearable glasses.

[0120] For example, wearable glasses can be wearable AR glasses and wearable VR glasses, etc.

[0121] Optionally, the temple back cover includes a temple back plate into which the inverted F antenna is embedded, and the temple back plate is located on the side of the temple away from the human body.

[0122] For example, the thickness of the temple backplate is less than 5 mm.

[0123] Compared to related technologies, the metal frames and displays of wearable AR and VR glasses can cause multipath effects, leading to beamforming distortion in the millimeter-wave band (28 / 39 GHz) and reducing the equivalent isotropic radiated power (EIRP) by 12-15 dB. In the wearable glasses provided in this application, a multi-layered metal shielding layer (such as a copper foil and silver paste composite layer) can be formed on the temple backplate and bonded to the grounding system with conductive adhesive (such as silver epoxy resin). The multi-layered metal shielding structure, through the synergistic effect of different materials (the high conductivity of copper and the high adhesion of silver paste), forms a low-impedance electromagnetic shielding path, suppressing multipath interference in the millimeter-wave band; the flexible properties of the conductive adhesive ensure a tight fit between the multi-layered metal shielding layer and the temple frame, reducing electromagnetic leakage.

[0124] In summary, the inverted-F antenna and wearable device provided in this application embodiment can be integrated into the back cover of the temple of a wearable device such as AR glasses to minimize radiation toward the human head. At the same time, a layer of metamaterial array further attenuates unwanted electromagnetic waves. This configuration achieves high positive gain, stable radiation pattern, efficient power transmission and SAR compliance by adopting a compact metamaterial array and optimized inverted-F antenna layout, and can be seamlessly integrated with AR glasses.

[0125] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. An inverted-F antenna, characterized by, Comprising: a inverted-F antenna body and a metamaterial array, wherein the inverted-F antenna body comprises a radiator that transmits electromagnetic waves toward a target radiation direction; the metamaterial array is disposed on a side of the radiator that is away from the target radiation direction to suppress back radiation of the inverted-F antenna.

2. The inverted-F antenna according to claim 1, wherein the metamaterial array comprises a plurality of periodically arranged metamaterial units that are configured to regulate the electromagnetic radiation direction of the inverted-F antenna body.

3. The inverted-F antenna according to claim 2, wherein the metamaterial units support broadband electromagnetic responses within a target frequency band, the target frequency band being between 5 GHz and 7.2 GHz.

4. The inverted-F antenna according to claim 2, wherein the metamaterial units satisfy a target planar size that is adapted to a spatial layout of a wearable device.

5. The inverted-F antenna according to any one of claims 1 to 4, wherein Further comprising: a substrate and a ground plate; the metamaterial array and the radiator are integrated on a same side surface of the substrate, and the ground plate is integrated on another side surface of the substrate.

6. The inverted-F antenna according to any one of claims 1 to 4, wherein, an input impedance of the inverted-F antenna body matches an output impedance of the wearable device, the input impedance being determined according to geometric parameters of the inverted-F antenna body, the geometric parameters including radiator structure parameters.

7. The inverted-F antenna according to any one of claims 1 to 4, wherein a length of the inverted-F antenna satisfies a preset size that is adapted to a spatial layout of the wearable device.

8. A wearable device, comprising: Comprising: a wearable device body and the inverted-F antenna as claimed in any one of claims 1 to 7.

9. The wearable device of claim 8, wherein, the wearable device comprises wearable glasses, and the inverted-F antenna is integrated in a temple back cover of the wearable glasses.

10. The wearable device of claim 9, wherein, the temple back cover comprises a temple back plate, the inverted-F antenna is embedded in the temple back plate, and the temple back plate is located on a side of a temple that is away from a human body.

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