Antenna structure and terminal device

Abstract

Provided in the embodiments of the present application are an antenna structure and a terminal device, relating to the technical field of electronic devices and being used for increasing bandwidth and reducing SAR. The antenna structure comprises: a first radiator formed on a first frame, a second radiator formed on a second frame, a third radiator arranged in an internal space enclosed by a frame, and a first matching network. The first radiator comprises a first end portion away from a first gap and a second end portion close to the first gap, and the second radiator comprises a first end portion close to the first gap and a second end portion away from the first gap; the third radiator is arranged along a first direction, and the orthographic projection of the third radiator on the frame at least partially overlaps with the first frame and the second frame; and the third radiator comprises a first end portion close to the first radiator and a second end portion close to the second radiator; a feed point is provided on the third radiator; and the second end portion of the third radiator is electrically connected to the second end portion of the second radiator by means of the first matching network.

Description

Antenna structure and terminal equipment

[0001] This application claims priority to Chinese patent application filed on August 27, 2024, with application number 202411192413.4 and entitled "Antenna Structure and Terminal Equipment", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electronic equipment technology, and in particular to an antenna structure and terminal equipment. Background Technology

[0003] With the rapid development of electronic technology, mobile phones and other wireless electronic devices with communication functions are becoming increasingly popular. Electronic devices typically include antennas to enable wireless communication, but these also generate electromagnetic radiation. The electromagnetic radiation from mobile phones and other wireless products has always been a matter of close public concern.

[0004] Given the impact of electromagnetic radiation from electronic devices on the human body, relevant industries have also put forward clear control requirements for the specific absorption rate (SAR) of antennas. SAR is a biophysical indicator that measures the potential impact of radio frequency electromagnetic radiation on human health. It is commonly used to assess the absorption rate of radio frequency energy generated by mobile phones, wireless network devices, or other wireless communication technologies. However, high-performance antennas and low SAR are often contradictory; the better the antenna performance, the higher its SAR. Therefore, there is an urgent need to design antenna solutions with low SAR and high efficiency. Summary of the Invention

[0005] This application provides an antenna structure and terminal device to reduce SAR in electronic devices and improve antenna efficiency of terminal devices.

[0006] The solution adopted in this application embodiment is as follows:

[0007] In a first aspect, embodiments of this application provide an antenna structure applied to a terminal device. The terminal device includes a frame, which includes a first frame and a second frame distributed along a first direction, with a first gap between the first frame and the second frame. The antenna structure includes: a first radiator formed on the first frame, a second radiator formed on the second frame, a third radiator disposed in the internal space enclosed by the frame, and a first matching network. The first radiator includes a first end away from the first gap and a second end near the first gap, with a grounding point provided at the first end of the first radiator. The second radiator includes a first end near the first gap and a second end away from the first gap. The third radiator is disposed along the first direction, and its orthographic projection on the frame at least partially overlaps with the first frame and the second frame. The third radiator includes a first end near the first radiator and a second end near the second radiator, with a feed point provided on the third radiator. The second end of the third radiator is electrically connected to the second end of the second radiator through the first matching network.

[0008] The antenna structure provided in this application embodiment sets a third radiator in the internal space enclosed by the frame. On the one hand, it does not occupy the frame resources. On the other hand, a current in the opposite direction to that in the first and second radiators can be formed on the third radiator, which can effectively increase the bandwidth and reduce SAR.

[0009] In one possible implementation, the length of the third radiator in the first direction is greater than the length of the second radiator in the first direction.

[0010] In one possible implementation, the feed point is located at the first end of the third radiator or between the first end and the second end.

[0011] In one possible implementation, a second matching network is also included. The second end of the first radiator is electrically connected to the first end of the second radiator via the second matching network. The capacitance value of the second matching network is adjustable, thereby allowing adjustment of the operating frequency of the antenna structure. The first and second matching networks enable the antenna to form two resonances, thus extending the antenna's operating frequency.

[0012] In one possible implementation, the first matching network comprises any one or more combinations of capacitors, inductors, microstrip lines, or resistors.

[0013] In one possible implementation, the antenna structure further includes a first tuning circuit, a first terminal of which is electrically connected to the second radiator, and a second terminal of which is grounded; the first tuning circuit includes a switching switch and multiple tuning devices, the switch being used to switch the connection relationship between the second radiator and the multiple tuning devices to change the operating frequency band of the antenna structure.

[0014] In one possible implementation, the first end of the first tuning circuit is electrically connected to the first or second end of the second radiator. The location of the first tuning circuit can have different benefits, and the specific configuration can be determined according to the actual application scenario.

[0015] In one possible implementation, the antenna structure further includes a fourth radiator. The first radiator, the second radiator, and the fourth radiator are arranged along a first direction. There is a second gap between the fourth radiator and the second radiator. The fourth radiator is coupled to the second radiator through the second gap. If there is sufficient frame resources, a fourth radiator can also be provided to expand the bandwidth of the antenna structure.

[0016] In one possible implementation, the fourth radiator includes a first end and a second end in a first direction, wherein the first end of the fourth radiator is close to the second slot and the second end of the fourth radiator is far from the second slot. The antenna structure also includes a second tuning circuit, the first end of which is electrically connected to the first end of the fourth radiator and the second end of which is grounded. The second tuning circuit includes a switching switch and a plurality of tuning devices. The switch is used to switch the connection relationship between the fourth radiator and the plurality of tuning devices to change the operating frequency band of the antenna structure.

[0017] Secondly, embodiments of this application provide a terminal device, which includes a frame, a first radiator, a second radiator, a third radiator, and a first matching network. The frame includes a first frame and a second frame distributed along a first direction, with a first gap between the first frame and the second frame. The first radiator is formed on the first frame, the second radiator is formed on the second frame, and the third radiator is disposed in the internal space enclosed by the frame. The first radiator includes a first end away from the first gap and a second end near the first gap, with a grounding point provided at the first end. The second radiator includes a first end near the first gap and a second end away from the first gap. The third radiator is disposed along the first direction, and its orthographic projection on the frame at least partially overlaps with the first frame and the second frame. The third radiator includes a first end near the first radiator and a second end near the second radiator, with a feed point provided on the third radiator. The second end of the third radiator is electrically connected to the second end of the second radiator through the first matching network.

[0018] In one possible implementation, the length of the third radiator in the first direction is greater than the length of the second radiator in the first direction.

[0019] In one possible implementation, the feed point is located at the first end of the third radiator or between the first end and the second end.

[0020] In one possible implementation, a second matching network is also included, wherein the second end of the first radiator is electrically connected to the first end of the second radiator via the second matching network, and the capacitance value of the second matching network is adjustable.

[0021] In one possible implementation, the first matching network comprises any one or more combinations of capacitors, inductors, microstrip lines, or resistors.

[0022] In one possible implementation, the terminal device further includes a first tuning circuit, a first terminal of which is electrically connected to the second radiator, and a second terminal of which is grounded.

[0023] The first tuning circuit includes a switching switch and multiple tuning devices. The switch is used to switch the connection relationship between the second radiator and the multiple tuning devices to change the operating frequency band of the terminal device.

[0024] In one possible implementation, a first terminal of the first tuning circuit is electrically connected to a first or second terminal of the second radiator.

[0025] In one possible implementation, the terminal device further includes a fourth radiator, with the first radiator, the second radiator and the fourth radiator arranged along a first direction, and a second gap between the fourth radiator and the second radiator, through which the fourth radiator is coupled to the second radiator.

[0026] In one possible implementation, the fourth radiator includes a first end and a second end in a first direction, wherein the first end of the fourth radiator is close to the second gap and the second end of the fourth radiator is far from the second gap. The terminal device also includes a second tuning circuit, the first end of which is electrically connected to the first end of the fourth radiator and the second end of which is grounded. The second tuning circuit includes a switching switch and a plurality of tuning devices. The switch is used to switch the connection relationship between the fourth radiator and the plurality of tuning devices to change the operating frequency band of the terminal device. Attached Figure Description

[0027] Figure 1 is a schematic diagram of a terminal device provided in an embodiment of this application;

[0028] Figure 2 is a schematic diagram of a general antenna structure;

[0029] Figure 3 is a schematic diagram of the head SAR and body SAR antenna structures;

[0030] Figure 4 is a schematic diagram of another terminal device provided in an embodiment of this application;

[0031] Figure 5 is a schematic diagram of an antenna structure provided in an embodiment of this application;

[0032] Figure 6 is a schematic diagram of another antenna structure provided in an embodiment of this application;

[0033] Figure 7 is a schematic diagram of the first matching network provided in an embodiment of this application;

[0034] Figure 8 is a schematic diagram of the first tuning circuit provided in an embodiment of this application;

[0035] Figure 9 is a current distribution diagram of an antenna structure provided in an embodiment of this application;

[0036] Figure 10 is a schematic diagram of the S-parameters of an antenna structure provided in an embodiment of this application;

[0037] Figure 11 is a schematic diagram of the radiation efficiency of an antenna structure provided in an embodiment of this application;

[0038] Figure 12 is a schematic diagram of another antenna structure provided in an embodiment of this application;

[0039] Figure 13 is a current distribution diagram of another antenna structure provided in an embodiment of this application;

[0040] Figure 14 is a schematic diagram of the S-parameters of another antenna structure provided in an embodiment of this application;

[0041] Figure 15 is a schematic diagram of the radiation efficiency of another antenna structure provided in an embodiment of this application;

[0042] Figure 16 is a schematic diagram of another antenna structure provided in an embodiment of this application;

[0043] Figure 17 is a current distribution diagram of another antenna structure provided in an embodiment of this application;

[0044] Figure 18 is a schematic diagram of the S-parameters of another antenna structure provided in an embodiment of this application;

[0045] Figure 19 is a schematic diagram of the radiation efficiency of another antenna structure provided in the embodiment of this application;

[0046] Figure 20 is a schematic diagram of another antenna structure provided in an embodiment of this application. Detailed Implementation

[0047] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0048] In the following description, the terms "first," "second," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units refer to two or more processing units.

[0049] Furthermore, in the embodiments of this application, "upper," "lower," "left," and "right" are not limited to the orientation of the components schematically placed in the accompanying drawings. It should be understood that these directional terms can be relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the components in the accompanying drawings. In the accompanying drawings, for clarity, the thickness of layers and regions is exaggerated, and the dimensional proportions between the parts in the drawings do not reflect the actual dimensional proportions.

[0050] In the embodiments of this application, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. In addition, the term "electrical connection" can be a direct electrical connection or an indirect electrical connection through an intermediate medium.

[0051] In this application, the term "module" typically refers to a logically divided functional structure. A "module" can be implemented purely in hardware, or a combination of hardware and software. In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, or both A and B existing simultaneously.

[0052] In this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being better or more advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0053] The antenna structure provided in this application embodiment can be applied to terminal devices such as mobile phones, tablets, smartwatches, and personal digital assistants (PDAs) to transmit and receive radio waves to transmit and exchange wireless signals. For ease of explanation, this application embodiment uses a mobile phone as an example to illustrate the technical solution of this application. Figures A and B in Figure 1 are schematic diagrams of the structure of the terminal device provided in this application embodiment. The terminal device may include: a frame 10, a display screen 20 covering one side of the frame and a back cover 30 covering the other side of the frame, and an antenna (not shown in the figure) located between the display screen 20 and the back cover 30.

[0054] The terminal device may also include a middle plate (not shown) located in the receiving space enclosed by the frame 10, the display screen 20 and the back cover 30. Circuit boards and batteries may be installed on the middle plate. Various components such as processors, memory, cameras, speakers, receivers, microphones, indicators and sensors may be installed on the circuit boards.

[0055] The frame 10 may include a left frame and a right frame that are positioned opposite each other, as well as a top frame and a bottom frame that connect the left and right frames; the frames are connected to each other to form a rectangular structure, and a certain curvature or chamfer may be formed at the connection points. The frame 10 may be integrally formed with the back cover 30, or integrally formed with the middle plate, or it may be fixedly connected to the back cover 30 and / or the middle plate through an assembly method.

[0056] The frame 10 can be a metal frame, such as copper, magnesium alloy or stainless steel; it can also be a non-metal frame, such as a plastic frame, glass frame, ceramic frame; or it can be a frame that combines metal and non-metal.

[0057] When the frame 10 may include a metal frame, the metal frame can be used as a radiator of the antenna. In a specific implementation, the metal frame can be broken into multiple metal segments through one or more gaps, and some or all of these metal segments can be used as radiators of the antenna, thereby achieving structural reuse.

[0058] The display screen 20 is used to realize the display function of the terminal device. It can be a curved screen or a non-curved screen. The display screen 20 can include a display panel and a cover plate. The cover plate is attached to the display panel to protect the display panel and receive user operations. The display panel can be a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, an active-matrix organic light-emitting diode (AMOLED) display, a flexible light-emitting diode (FLED) display, a mini light-emitting diode display, a micro light-emitting diode display, quantum dot light-emitting diodes (QLED), etc.

[0059] The back cover 30 can be a metal back cover, or a glass back cover, a ceramic back cover, or a plastic back cover, etc. The material of the back cover 30 is not particularly limited in this embodiment.

[0060] The device may have one or more antennas, which may be used to transmit and receive low-frequency signals, intermediate-frequency signals, and / or high-frequency signals. The antennas may be located in or near any of the four border areas of the terminal device: top, bottom, left, and right.

[0061] The antenna can be implemented using flexible printed circuit (FPC), laser-direct-structuring (LDS) antennas, metal device antennas (MDA), or metal frames, or a combination of at least two of these methods. This application does not impose any particular limitation on the specific implementation of the antenna. The MDA antenna is a low-cost antenna implementation that utilizes an aluminum alloy or other metal structural component embedded in a housing as the antenna radiator. The radiator is formed within a non-metallic housing (such as a plastic frame). In some embodiments, the MDA antenna is also referred to as a pattern-decorative antenna, in-mold injection molding antenna, or other names.

[0062] This application does not limit the communication system used by the terminal device. For example, the terminal device can be applied to the following communication systems: Global System for Mobile Communication (GSM), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), General Packet Radio Service (GPRS), Long Term Evolution (LTE) system, LTE-Advanced (A), Universal Mobile Telecommunications System (UMTS), and other future communication systems.

[0063] For wireless communication terminal devices, the specific absorption rate (SAR) is a biophysical indicator that measures the potential health effects of radio electromagnetic radiation. It is commonly used to assess the absorption rate of radio frequency energy generated by mobile phones, wireless terminal devices, or other wireless communication technologies.

[0064] SAR (Radio Frequency Absorption) represents the amount of radio frequency energy absorbed per unit mass of tissue (e.g., per kilogram of human body) per unit time. According to international safety standards, wireless devices used by the public should have their SAR values ​​limited to a certain range, such as less than 1.6 watts per kilogram (W / kg) on ​​average for an adult. A lower SAR means less radiation impact on the body, while excessively high SAR can lead to long-term thermal effects, such as fatigue or increased cancer risk. Manufacturers need to conduct rigorous testing to ensure that their products are designed to meet SAR limits to protect users' health and safety.

[0065] High-performance antennas and low SAR are often contradictory; the better the antenna performance, the higher the SAR. Therefore, there is an urgent need to design antenna schemes with low SAR and high efficiency. Taking mobile phones and other terminal devices as examples, Figure 2 presents a general frame antenna scheme. Figure A in Figure 2 shows a partial structural schematic diagram of the terminal device, and Figure B shows an equivalent schematic diagram of the frame antenna of the terminal device. For example, the frame 10 of the terminal device may include a first frame 11 and a second frame 12. The antenna 40 of the terminal device may include a first radiator 41 and a second radiator 42. The first radiator 41 and the second radiator 42 are connected by a matching network M. The first radiator 41 can be formed on the first frame 11, and the second radiator 42 can be formed on the second frame 12. The antenna frequency is adjusted by the matching network M between the two radiators to improve the antenna efficiency. However, such an antenna structure has a large SAR reduction. Figure 3 shows a schematic diagram of the head SAR and body SAR of this antenna. Referring to Table 1, Table 1 shows the head SAR and body SAR values ​​of this antenna structure at different frequencies.

[0066] Table 1

[0067] SAR refers to the electromagnetic power absorbed per unit mass of human tissue, measured in W / kg. 10g represents the volume of biological tissue fluid in units of 10g (equivalent to 10cm). 3 The standard is used for testing; the right head SAR value refers to the SAR value when the user places the phone on the right side of their head; the 5mm SAR behind the body refers to the SAR value when the back of the phone is 5mm away from the user's body, and the 5mm SAR to the left of the body refers to the SAR value when the left side of the phone is 5mm away from the user's body. The normalized SAR value refers to the SAR value normalized to -4dB. As can be seen from Table 1, the antenna bandwidth shown in Figure 2 is relatively narrow, and the head-mode SAR value and body SAR value are relatively large, resulting in poor free-space radiation performance.

[0068] To address the aforementioned issues, this application provides a terminal device with an improved antenna structure, thereby reducing the SAR value of the terminal device. Referring to FIG4, FIG4 shows a simplified view of the terminal device provided in this application embodiment. The terminal device may include a frame 10, which may include a first frame 11 and a second frame 12 distributed along a first direction. A first gap 101 is provided between the first frame 11 and the second frame 12. The terminal device may also include other structures or components, which are not shown in FIG4.

[0069] Referring to Figures 4 and 5, Figure A in Figure 5 shows a first perspective view of the antenna structure, and Figure B in Figure 5 shows a second perspective view of the antenna structure. The antenna structure 40 may include a first radiator 41, a second radiator 42, and a third radiator 43. The first radiator 41 is formed on a first frame 11, and the second radiator 42 is formed on a second frame 12. A first gap 101 exists between the first radiator 41 and the second radiator 42. The first radiator 41 may include a first end 411 away from the first gap 101 and a second end 412 near the first gap 101. The second radiator 42 may include a first end 421 near the first gap 101 and a second end 422 away from the first gap 101. The antenna structure shown in Figure 5 is merely an example to illustrate the structure and positional relationship of the first radiator 41, the second radiator 42, and the third radiator 43. The antenna structure may also include components not shown or labeled in Figure 5. Therefore, the antenna structure 40 will be described here in conjunction with Figures 4, 5, and 6.

[0070] For example, the aforementioned frame 10 can be a metal frame, in which case the first frame 11 can serve as the first radiator 41, and the second frame 12 can serve as the second radiator 42. The first radiator 41 and the second radiator 42 are metal frame antennas. In some other possible implementations, the frame can also be a non-metallic frame, and the first radiator 41 and the second radiator 42 can also serve as MDA antennas. In this case, the first radiator 41 can be formed within the first frame 11 by in-mold injection molding, and the second radiator 42 can be formed within the second frame 12 by in-mold injection molding.

[0071] In the embodiments of this application, the end of the radiator cannot be narrowly understood as a point. It can also be considered as a segment of the radiator that may include an endpoint (the endpoint of the radiator can be any point on the edge of the radiator). For example, the first end of the radiator can be considered as the radiator within a certain distance from the first endpoint of the radiator. For example, the radiator within 1 / 3 of the length can be considered as the first end of the radiator. The second end of the radiator can also be understood accordingly.

[0072] Due to the limited border resources of the terminal device, please refer to Figure 4. Although the border 10 may also include a third border 13 in the first direction, the third border 13 may be used as an antenna for other frequency bands. For example, the antenna structure provided in this application embodiment can be used as a middle high band (MHB) antenna, and the third border may be used as a low band (LB) antenna. Therefore, the antenna structure provided in this application embodiment may not be able to be further extended on the border 10. In this application embodiment, the third radiator is disposed in the internal space enclosed by the border of the terminal device. For example, referring to Figure 5, the third radiator 43 may be disposed on a bracket or substrate. The substrate may be the motherboard or other circuit board of the terminal device. Alternatively, the third radiator 43 may also be fixed in the internal space enclosed by the border in other ways.

[0073] Referring to Figures 4, 5, and 6, Figure 6 is an equivalent schematic diagram of the antenna structure provided in the embodiment of this application. The third radiator 43 is disposed along the first direction, and the length of the third radiator 43 in the first direction is greater than the length of the second radiator 42 in the first direction. The orthographic projection of the third radiator 43 on the frame overlaps at least partially with the first frame 11 and the second frame 12. The third radiator 43 may also include a first end 431 and a second end 432 in the first direction. The first end 431 of the third radiator 43 is close to the first radiator 41, and the second end of the third radiator 43 is close to the second radiator 42. The second end of the third radiator 43 is electrically connected to the second end 422 of the second radiator 42 through the first matching network M1.

[0074] For example, a feed point may be provided on the third radiator 43. The feed point is also called the antenna input point. The antenna feed point refers to the interface used by the antenna to receive the signal to be transmitted. The feed point may be provided at the first end 431 of the third radiator 43 or between the first end 431 and the second end 432. A grounding point may be provided on the first radiator 41.

[0075] For example, the third radiator 43 can be a metal sheet, such as a steel bracket, or it can also be a flexible circuit board, an LDS antenna, etc. For instance, if the third radiator 43 is a steel bracket, it can be fixedly mounted on the circuit board of the terminal device, reducing both head SAR and body SAR without occupying the frame size.

[0076] The antenna structure 40 may also include a second matching network M2. The first end 421 of the second radiator 42 can be electrically connected to the second end 412 of the first radiator 41 through the second matching network M2. The capacitance value of the second matching network M2 is adjustable. For example, the second matching network M2 can be an adjustable capacitor. By adjusting the capacitance value of the second matching network M2, the antenna structure 40 can be tuned, thereby adjusting the operating frequency of the antenna structure 40.

[0077] For example, the second end 432 of the third radiator 43 can be electrically connected to the first matching network M1, and the first matching network M1 can also be electrically connected to the second end 422 of the second radiator 42. Referring to Figures 7(a) to (e), the first matching network M1 can be any one or a combination of capacitors, inductors, microstrip lines or resistors. This application embodiment does not limit this.

[0078] Please refer to Figure 6. The antenna structure 40 may also include a first tuning circuit 45. The first end of the first tuning circuit 45 may be electrically connected to the second radiator 42, and the second end of the first tuning circuit 45 is grounded. Referring to Figure 8, the first tuning circuit 45 may include a switching switch and multiple tuning devices. For example, the first tuning circuit 45 may include switches S1, S2, and S3. The switches are used to switch the connection relationship between the second radiator 42 and multiple tuning devices to adjust the operating frequency of the antenna structure 40. For example, switch S1 is used to switch the conduction state of tuning device Z1, switch S2 is used to switch the conduction state of tuning device Z2, and switch S3 is used to switch the conduction state of tuning device Z3. Here, tuning devices Z1, Z2, and Z3 may be capacitors, or they may be resistors, inductors, or other tuning devices. The first tuning circuit 45 may also include a greater number of switches and tuning devices.

[0079] The feed point on the third radiator 43 can be set at the first end 431 of the third radiator 43 or between the first end 431 and the second end 432. Depending on the feed point position on the third radiator 43, the device selection or parameters of the first matching network M1 can be different in order to achieve better antenna radiation efficiency.

[0080] Referring to Figure 6, in one possible implementation, the feed point of the third radiator 43 is located at the first end 431 of the third radiator 43. The first matching network M1 can be any one or a combination of capacitors, inductors, microstrip lines, or resistors. The antenna structure 40 provided in this embodiment can form two resonances. By adjusting the second matching network M2 and the first tuning circuit 45, the antenna structure 40 can adjust these two resonances. Specifically, the first radiator 41, the second radiator 42, and the third radiator 43 can form the first resonance, where the currents of the first radiator 41 and the second radiator 42 and the third radiator 43 are opposite, which can reduce SAR. The second radiator 42 and the third radiator 43 can form the second resonance, where the currents of the first radiator 41 and the second radiator 42 and the third radiator 43 are in the same direction, which can improve the radiation efficiency of the antenna structure 40.

[0081] Figure 9A shows the current distribution of the first resonance, Figure 9B shows the current distribution of the second resonance, Figure 10 shows a schematic diagram of the S-parameters of the antenna structure provided in this embodiment, and Figure 11 shows a schematic diagram of the radiation efficiency of the antenna structure provided in this embodiment. In Figure 10, the horizontal axis represents frequency in GHz, and the vertical axis represents the S11 parameter in dB. The S11 parameter is a type of S-parameter, representing the reflection coefficient. This parameter characterizes the antenna's transmission efficiency. Specifically, the smaller the S11 value, the smaller the antenna return loss, the less energy reflected back by the antenna itself, and the more energy actually enters the antenna. As can be seen from Figure 10, the antenna structure provided in this embodiment can generate two resonances, covering a wide frequency range. By adjusting the frequencies of the two resonances, it can cover mid-to-high frequencies.

[0082] In Figure 11, the horizontal axis represents frequency in GHz, and the vertical axis represents the antenna's radiation efficiency. Radiation efficiency is a measure of an antenna's radiation capability. As those skilled in the art will understand, efficiency is generally expressed as a percentage, and there is a corresponding conversion relationship between it and dB. The closer the efficiency is to 0 dB, the better the antenna's efficiency. As can be seen from Figure 11, the antenna structure provided in this embodiment can meet the radiation efficiency requirements in the mid-to-high frequency bands.

[0083] The first resonance can be adjusted by adjusting the second matching network M2. The first end of the first tuning circuit 45 can be electrically connected to the second end 422 of the second radiator 42. The second resonance can be adjusted by adjusting the first tuning circuit 45.

[0084] As can be seen from Figures 9 to 11, at the first resonance, the current direction on the third radiator 43 is opposite to the current direction on the second radiator 42 and the first radiator 41, which can effectively reduce head SAR and body SAR. At the second resonance, the current in the first radiator 41 is in the same direction as the current in the second radiator 42 and the third radiator 43, which can improve the radiation efficiency of the antenna structure 40.

[0085] By adjusting the second matching network M2 and the first tuning circuit 45, the bandwidth of the antenna structure 40 can cover the entire mid-to-high frequency band, increase antenna stubs, and widen the antenna bandwidth, thus achieving good coverage on both the receiving and transmitting sides. Table 2 shows the SAR values ​​of the antenna structure provided in the embodiments of this application.

[0086] Table 2

[0087] Comparing Table 1 and Table 2, it can be seen that, compared with the antenna structure shown in Figure 2, the antenna structure provided in this application embodiment has reduced head SAR and body SAR, which can effectively reduce head SAR and body SAR.

[0088] In another possible implementation, the feed point on the third radiator 43 can be located between the first end 431 and the second end 432. For example, referring to Figure 12, the feed point on the third radiator 43 can be located in the middle of the third radiator 43. The middle can be understood as the central region of the radiator, that is, the region formed at a certain distance from the midpoint of the radiator. The midpoint of the radiator can be the geometric center (the length of the radiator on both sides of the geometric midpoint is the same); or, the midpoint of the radiator can also be the midpoint of the electric length of the radiator (the electric length of the radiator on both sides of the midpoint is the same).

[0089] In this case, the first matching network M1 can be a capacitor or a 0-ohm resistor. The first terminal of the first tuning circuit 45 can be electrically connected to the first terminal 421 of the second radiator 42. Based on the antenna structure 40 provided in this embodiment, a resonance can be formed, which reduces SAR while increasing antenna bandwidth. Figure 13 shows a schematic diagram of the current distribution of the antenna structure provided in this embodiment, and Table 3 shows the SAR values ​​of the antenna structure provided in this embodiment.

[0090] Table 3

[0091] Comparing Tables 1 and 3, it can be seen that, compared with the antenna structure shown in Figure 2, the head SAR and body SAR of the antenna structure provided in this application embodiment are reduced.

[0092] Figure 14 shows a schematic diagram of the S-parameters of the antenna structure provided in this embodiment, and Figure 15 shows a schematic diagram of the radiation efficiency of the antenna structure provided in this embodiment. Combining Figures 14 and 15, it can be seen that the antenna structure provided in this embodiment has a resonance. By adjusting this resonance frequency, the antenna structure achieves good impedance matching in the frequency band of approximately 1.8 GHz to 2.6 GHz, with S11 less than -10 dB. Referring to Figure 15, the antenna's system efficiency is good in the mid-to-high frequency band, meeting the radiation efficiency requirements.

[0093] In some possible implementations, if the border resources of the terminal device are sufficient, referring to Figure 2, the border may also include a third border 13. The first border 11, the second border 12 and the third border 13 are arranged along the first direction. The third border 13 can also be used as the antenna structure provided in the embodiments of this application. There is a first gap 101 between the first border 11 and the second border 12, and a second gap 102 between the second border 12 and the third border 13.

[0094] Referring to Figure 16, the antenna structure 40 may further include a fourth radiator 44, which may be formed on the third frame 13. That is, the first radiator 41, the second radiator 42 and the fourth radiator 44 are arranged along the first direction, and there is a second gap 102 between the fourth radiator 44 and the second radiator 42. The fourth radiator 44 is coupled to the second radiator 42 through the second gap 102.

[0095] The fourth radiator 44 may include a first end 441 and a second end 442 in a first direction, wherein the first end 441 of the fourth radiator 44 is close to the second slit 102, and the second end 442 of the fourth radiator 44 is away from the second slit 102.

[0096] The antenna structure 40 may further include a second tuning circuit 46. The second tuning circuit 46 may include a first terminal and a second terminal. The first terminal of the second tuning circuit 46 is electrically connected to the first end 441 of the fourth radiator 44, and the second terminal of the second tuning circuit 46 is grounded. The second tuning circuit 46 may include a switching switch and multiple tuning devices. The switch is used to switch the connection relationship between the fourth radiator 44 and the multiple tuning devices to change the operating frequency band of the antenna structure 40. The structure of the second tuning circuit 46 can refer to the structure and principle of the first tuning circuit described above, and will not be repeated in this embodiment. The first tuning circuit and the second tuning circuit 46 may also be other types or structures of tuning circuits, not limited to the structures provided in this embodiment.

[0097] After adding a fourth radiator 44 and a second tuning circuit 46, the antenna structure can form three resonances by adjusting the second matching network M2, the first tuning circuit 45, and the second tuning circuit 46. Figures A, B, and C in Figure 17 show the current distribution of the three resonances of the antenna structure provided in this embodiment. Figure 18 shows a schematic diagram of the S-parameters of the antenna structure provided in this embodiment. By adjusting the frequencies of the three resonances, the antenna structure can have good impedance matching in the range of 1.7 GHz to 2.8 GHz. Figure 19 shows a schematic diagram of the radiation efficiency of the antenna structure provided in this embodiment. Combining Figures 18 and 19, after adding the fourth radiator 44, the antenna bandwidth is further expanded and the efficiency is improved while reducing SAR. The resonant frequency of the antenna structure can be adjusted by adjusting the size of the second matching network M2, the first tuning circuit, the second tuning circuit, the second slot, and the size of the fourth radiator, resulting in a wider coverage band. The antenna bandwidth is expanded while reducing head SAR and body SAR. The antenna scheme provided in this embodiment increases the antenna bandwidth by adding parasitics. By adjusting the dimensions of M1, M2, M3, the coupling gap, and the parasitic structure, the bandwidth can be made to cover the entire mid-to-high frequency band.

[0098] Table 4 shows the head SAR and body SAR values ​​of the antenna structure provided in the embodiments of this application.

[0099] Table 4

[0100] Comparing Tables 1 and 4, it can be seen that, compared with the antenna structure shown in Figure 2, the head SAR and body SAR of the antenna structure provided in this application embodiment are reduced.

[0101] Alternatively, in another possible implementation, based on Figure 12 and referring to Figure 20, the antenna structure 40 may further include a fourth radiator 44, which may be formed on the third frame 13. That is, the first radiator 41, the second radiator 42 and the fourth radiator 44 are arranged along the first direction, and there is a second gap 102 between the fourth radiator 44 and the second radiator 42. The fourth radiator 44 is coupled to the second radiator 42 through the second gap 102.

[0102] In the above embodiments, the feed point of the antenna structure is located on the third radiator. In some other possible implementations, the feed point of the antenna structure can be moved to different branches and different locations; or, other feed points can be added to the antenna structure. Furthermore, corresponding to the first and second tuning circuits described above, they can also be located on different antenna radiators or in different positions to switch the resonant frequency of the antenna structure.

[0103] The above embodiments use a mobile phone as an example to illustrate the solution provided in this application. The terminal device provided in this application can also be a tablet computer, smartwatch, or other terminal device; this application does not limit the specific terminal device. Furthermore, the antenna structure provided in this application is not limited to high-frequency antennas on the side bezel of the terminal device; it can also be applied to bezel antennas in different locations, such as the bottom or top bezel. The antenna frequency band can also be applied to other frequency bands, such as the wireless fidelity (Wi-Fi) band.

[0104] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An antenna structure, characterized in that, Applied to a terminal device, the terminal device includes a frame, the frame includes a first frame and a second frame distributed along a first direction, and a first gap is provided between the first frame and the second frame; The antenna structure includes: a first radiator formed on the first frame, a second radiator formed on the second frame, a third radiator disposed in the internal space enclosed by the frames, and a first matching network; The first radiator includes a first end away from the first gap and a second end close to the first gap. The first end of the first radiator is provided with a grounding point. The second radiator includes a first end close to the first gap and a second end away from the first gap. The third radiator is disposed along the first direction, and the orthographic projection of the third radiator on the frame overlaps at least partially with the first frame and the second frame. The third radiator includes a first end near the first radiator and a second end near the second radiator. The third radiator is provided with a feed point, and the second end of the third radiator is electrically connected to the second end of the second radiator through the first matching network.

2. The antenna structure according to claim 1, characterized in that, The length of the third radiator in the first direction is greater than the length of the second radiator in the first direction.

3. The antenna structure according to claim 2, characterized in that, The feed point is located at the first end of the third radiator or between the first end and the second end.

4. The antenna structure according to claim 3, characterized in that, It also includes a second matching network, through which the second end of the first radiator is electrically connected to the first end of the second radiator, and the capacitance value of the second matching network is adjustable.

5. The antenna structure according to claim 3 or 4, characterized in that, The first matching network includes any one or more combinations of capacitors, inductors, microstrip lines, or resistors.

6. The antenna structure according to any one of claims 3 to 5, characterized in that, The antenna structure further includes a first tuning circuit, a first terminal of which is electrically connected to the second radiator, and a second terminal of which is grounded. The first tuning circuit includes a switching switch and multiple tuning devices. The switch is used to switch the connection relationship between the second radiator and the multiple tuning devices to change the operating frequency band of the antenna structure.

7. The antenna structure according to claim 6, characterized in that, The first terminal of the first tuning circuit is electrically connected to the first or second end of the second radiator.

8. The antenna structure according to any one of claims 1 to 7, characterized in that, The antenna structure further includes a fourth radiator. The first radiator, the second radiator, and the fourth radiator are arranged along the first direction. There is a second gap between the fourth radiator and the second radiator. The fourth radiator is coupled to the second radiator through the second gap.

9. The antenna structure according to claim 8, characterized in that, The fourth radiator includes a first end and a second end in a first direction, wherein the first end of the fourth radiator is close to the second gap, and the second end of the fourth radiator is far from the second gap. The antenna structure also includes a second tuning circuit, wherein a first end of the second tuning circuit is electrically connected to the first end of the fourth radiator, and a second end of the second tuning circuit is grounded. The second tuning circuit includes a switching switch and multiple tuning devices. The switch is used to switch the connection relationship between the fourth radiator and the multiple tuning devices to change the operating frequency band of the antenna structure.

10. A terminal device, characterized in that, The terminal device includes a frame, a first radiator, a second radiator, a third radiator, and a first matching network. The frame includes a first frame and a second frame distributed along a first direction. There is a first gap between the first frame and the second frame. The first radiator is formed on the first frame, the second radiator is formed on the second frame, and the third radiator is disposed in the internal space enclosed by the frame. The first radiator includes a first end away from the first gap and a second end close to the first gap. The first end of the first radiator is provided with a grounding point. The second radiator includes a first end close to the first gap and a second end away from the first gap. The third radiator is disposed along the first direction, and the orthographic projection of the third radiator on the frame overlaps at least partially with the first frame and the second frame. The third radiator includes a first end near the first radiator and a second end near the second radiator. The third radiator is provided with a feed point, and the second end of the third radiator is electrically connected to the second end of the second radiator through the first matching network.

11. The terminal device according to claim 10, characterized in that, The length of the third radiator in the first direction is greater than the length of the second radiator in the first direction.

12. The terminal device according to claim 11, characterized in that, The feed point is located at the first end of the third radiator or between the first end and the second end.

13. The terminal device according to claim 12, characterized in that, It also includes a second matching network, through which the second end of the first radiator is electrically connected to the first end of the second radiator, and the capacitance value of the second matching network is adjustable.

14. The terminal device according to claim 13, characterized in that, The first matching network includes any one or more combinations of capacitors, inductors, microstrip lines, or resistors.

15. The terminal device according to any one of claims 10 to 14, characterized in that, The terminal device further includes a first tuning circuit, a first terminal of which is electrically connected to the second radiator, and a second terminal of which is grounded. The first tuning circuit includes a switching switch and multiple tuning devices. The switch is used to switch the connection relationship between the second radiator and the multiple tuning devices to change the operating frequency band of the terminal device.

16. The terminal device according to claim 15, characterized in that, The first terminal of the first tuning circuit is electrically connected to the first or second end of the second radiator.

17. The terminal device according to any one of claims 10 to 16, characterized in that, The terminal device further includes a fourth radiator. The first radiator, the second radiator, and the fourth radiator are arranged along the first direction. There is a second gap between the fourth radiator and the second radiator. The fourth radiator is coupled to the second radiator through the second gap.

18. The terminal device according to claim 17, characterized in that, The fourth radiator includes a first end and a second end in a first direction, wherein the first end of the fourth radiator is close to the second gap, and the second end of the fourth radiator is far from the second gap. The terminal device further includes a second tuning circuit, wherein a first end of the second tuning circuit is electrically connected to the first end of the fourth radiator, and a second end of the second tuning circuit is grounded. The second tuning circuit includes a switching switch and multiple tuning devices. The switch is used to switch the connection relationship between the fourth radiator and the multiple tuning devices to change the operating frequency band of the terminal device.

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