An antenna structure and a mobile terminal

Abstract

This application provides an antenna structure and a mobile terminal. The antenna structure includes a radiator and an impedance matching circuit. The radiator includes a first stub and a second stub connected together. The end of the first stub facing away from the second stub is an open end. The first stub includes a feed point. The end of the second stub facing away from the first stub is grounded. The connection point between the first and second stubs is grounded through an inductive structure. The physical length L1 of the first stub and the physical length L2 of the second stub satisfy 4 / 5 ≤ L1 / L2 ≤ 4 / 3. The distance d between the feed point and the end of the first stub facing away from the second stub satisfies d ≤ 1 / 4 × L1. The impedance matching circuit is electrically connected to the feed point and includes an inductor. This application constructs the antenna structure as a co-directional slot antenna, so that the electric fields generated by each part of the radiator of the antenna structure are in the same direction, thereby facilitating the tuning of the radiation pattern of the antenna structure towards the display screen side and optimizing the grip performance of the antenna structure.

Description

[0001] This application is a divisional application. The original application has the application number 202410259371.5 and the original application date is March 4, 2024. The entire contents of the original application are incorporated herein by reference. Technical Field

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

[0003] With the development of mobile communications, the usage rate of mobile terminals is increasing. Network coverage of mobile cellular networks is crucial for mobile communications, and the key equipment used to achieve network coverage in mobile cellular networks is the antenna.

[0004] In current mobile terminals, the frame antenna used to radiate low-frequency signals is typically located on one side of the battery compartment. The length of its radiator is approximately one-quarter of the wavelength corresponding to the center frequency of the antenna's resonant frequency. This antenna has high radiation efficiency in free space. However, when a user holds the mobile terminal, much of the energy radiated by the frame antenna towards the back of the terminal is covered by the hand. Therefore, the radiated energy of the frame antenna decreases significantly when the user holds the terminal, thus affecting its radiation performance.

[0005] Therefore, how to ensure the radiation efficiency of the antenna in free space while effectively reducing the reduction in radiation energy when the mobile terminal is held in hand has become a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] This application provides an antenna structure and a mobile terminal that optimizes the hand grip performance of the antenna structure while ensuring its radiation efficiency in free space, thereby improving the communication performance of the mobile terminal.

[0007] Firstly, this application provides an antenna structure including a radiator and an impedance matching circuit. The radiator includes a first stub and a second stub connected together. The end of the first stub facing away from the second stub is an open end. The first stub includes a feed point. The end of the second stub facing away from the first stub is grounded, and the connection point between the first and second stubs is grounded through an inductive structure. Furthermore, the physical length L1 of the first stub and the physical length L2 of the second stub satisfy 4 / 5 ≤ L1 / L2 ≤ 4 / 3. The distance d between the feed point and the end of the first stub facing away from the second stub satisfies d ≤ 1 / 4 × L1. In addition, the impedance matching circuit is electrically connected to the feed point and includes an inductor. In this application, by constructing the antenna structure as a co-directional slot antenna, the electric fields generated by each part of the radiator of the antenna structure are made to be in the same direction, thereby facilitating the tuning of the radiation pattern of the antenna structure towards the display screen side. This ensures the radiation efficiency of the antenna structure in free space while also optimizing the grip performance of the antenna structure.

[0008] The antenna structure provided in this application can be used to operate in low-frequency bands, wherein the low-frequency bands include at least one communication band within the range of 600MHz-1GHz.

[0009] In addition, the inductor in the impedance matching circuit can be used to perform impedance matching on the antenna structure, thereby adjusting the resonant frequency generated by the antenna structure. In one possible implementation, the inductance value of the inductor in the impedance matching circuit is greater than or equal to 15nH to meet the impedance matching requirements of the antenna structure, which is beneficial for the antenna structure to generate an antenna mode similar to a slot antenna.

[0010] In one possible implementation of this application, the antenna structure further includes a tuning circuit, one end of which is grounded, and the other end of which is electrically connected between the impedance matching circuit and the feed point. Additionally, the tuning circuit includes at least one capacitor. This at least one capacitor in the tuning circuit can be used for frequency tuning; that is, when the corresponding capacitor is electrically connected between the impedance matching circuit and the feed point, the antenna structure can operate in the corresponding communication frequency band.

[0011] In this application, the capacitance value of at least one capacitor in the tuning circuit is less than or equal to 2pF. This is beneficial for the antenna structure to generate an antenna pattern similar to a slot antenna.

[0012] Furthermore, when the tuning circuit includes multiple capacitors, these capacitors are connected in parallel. This allows for switching of the communication frequency band of the antenna structure in the low-frequency band by electrically connecting different capacitors between the impedance matching circuit and the feed point.

[0013] The antenna structure provided in this application may further include a feeding circuit, with an impedance matching circuit electrically connected between the feeding circuit and the feeding point. The feeding circuit can be used for feeding or transmitting radio frequency signals, thereby enabling the antenna structure to receive or transmit radio frequency signals.

[0014] Secondly, this application also provides a mobile terminal. The mobile terminal includes a frame and an antenna structure as described in the first aspect. The frame is circumferentially arranged around the periphery of the mobile terminal, and the radiator of the antenna structure is disposed on one side of the frame. The radiator of the antenna structure can be a conductive part on the frame, such as the conductive frame itself, or the radiator can be a conductive part on a non-conductive frame. The antenna for low-frequency bands in the mobile terminal provided by this application adopts the above-described antenna structure design, which can effectively improve the radiation pattern of the antenna structure facing the display screen side. This ensures the radiation efficiency of the antenna structure in free space while also optimizing the radiation performance of the antenna structure when the mobile terminal is held in hand.

[0015] In one possible implementation of this application, the mobile terminal further includes a mid-frame located within the area enclosed by the border. The end of the second branch facing away from the first branch is connected to the mid-frame to ground the second branch. Additionally, the connection point between the first and second branches is connected to the mid-frame via an inductive structure, thereby grounding the connection point between the first and second branches.

[0016] Since the antenna structure provided in this application operates in the low-frequency band, it is positioned near the bottom of the mobile terminal. The mid-frame includes a battery compartment for housing the battery, which is also positioned near the bottom of the mobile terminal. In one possible implementation of this application, the radiator is located on one side of the frame facing the battery compartment, and along the direction from the second branch to the first branch, the connection point between the first and second branches is lower than the top of the battery compartment. This improves the utilization rate of the portion of the frame opposite the battery compartment and increases the physical length of the radiator, thereby increasing the aperture of the antenna structure.

[0017] This application does not limit the specific arrangement of the inductive structure. For example, the inductive structure may include a grounding tie rod located between the battery compartment and the radiator. One end of the grounding tie rod is connected to the connection point of the first and second branches, and the other end is connected to the middle frame.

[0018] In another possible implementation of this application, the grounding rib, the middle frame, and the edge frame can also be integrally formed. This ensures the reliability of the grounding connection between the first and second branches through the grounding rib, and also helps to improve the structural integration of the mobile terminal. In addition, it makes it easier to control the space occupied by the grounding rib, so as to reserve sufficient space for the battery and thus meet the battery capacity requirements.

[0019] In one possible implementation of this application, the sensory structure can also be an independent structural component, with the sensory portion of the sensory structure connected to the connection point of the first and second branches, and also connected to the middle frame. This can improve the flexibility of the sensory structure's configuration.

[0020] In one possible implementation of this application, a clear space exists between the radiator and the frame. This ensures a good radiation environment for the radiator, thereby improving signal transmission quality and coverage. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a mobile terminal provided in an embodiment of this application;

[0022] Figure 2 This is a schematic diagram illustrating the existing frame antenna configuration in a mobile terminal.

[0023] Figure 3a for Figure 2 Color diagram of the current distribution of the frame antenna shown;

[0024] Figure 3b for Figure 3a The grayscale image corresponding to the color image of the current distribution diagram shown in the figure;

[0025] Figure 4a for Figure 2 Color image of the free-space radiation pattern of the frame antenna shown;

[0026] Figure 4b for Figure 4a The grayscale image corresponding to the color directional pattern shown in the diagram;

[0027] Figure 5a for Figure 2 The color image shows the radiation pattern of the frame antenna when the mobile terminal is held in the left hand position;

[0028] Figure 5b for Figure 5a The grayscale image corresponding to the color directional pattern shown in the diagram;

[0029] Figure 6a for Figure 2 The color image shows the radiation pattern of the frame antenna when the mobile terminal is held in the right hand position.

[0030] Figure 6b for Figure 6a The grayscale image corresponding to the color directional pattern shown in the diagram;

[0031] Figure 7 A simplified schematic diagram of the structure of a mobile terminal provided in an embodiment of this application;

[0032] Figure 8a for Figure 7 A color illustration of the current flow direction of the antenna structure shown.

[0033] Figure 8b for Figure 8a The grayscale image corresponding to the color diagram of the current flow direction shown in the figure;

[0034] Figure 9 for Figure 7 A schematic diagram of the current amplitude distribution of the antenna structure shown;

[0035] Figure 10a A color illustration of the electric field distribution of the antenna structure shown in Figure 7;

[0036] Figure 10b for Figure 10a The grayscale image corresponding to the color diagram of the electric field distribution shown in the figure;

[0037] Figure 11a Color diagram of the antenna structure in free space provided in the embodiments of this application;

[0038] Figure 11b for Figure 11a The grayscale image corresponding to the color directional pattern shown in the diagram;

[0039] Figure 12 The antenna structure provided in the embodiments of this application and Figure 2 The diagram shows a comparison of the radiation efficiency of existing frame antennas in free space.

[0040] Figure 13 The antenna structure provided in the embodiments of this application and Figure 2 The diagram shows a comparison of the radiation efficiency of existing frame antennas when held in hand.

[0041] Figure label:

[0042] 010-Mobile terminal; 011-Cover plate; 012-Display / module; 013-Printed circuit board; 014-Middle frame; 0141-Battery compartment; 015-Back cover;

[0043] 016 - Border; 0161 - Seam;

[0044] 1-Radiator; 101-Feed point; 1a-First stub; 1b-Second stub; 2-Impedance matching circuit; 201-Inductor; 3-Tuning circuit;

[0045] 301 - Capacitor; 4 - Inductive structure; 401 - Grounding tie. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein. The same reference numerals in the figures denote the same or similar structures, and therefore repeated descriptions of them will be omitted. The terms expressing position and direction described in the embodiments of this application are illustrative based on the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this application. The accompanying drawings of the embodiments of this application are only for illustrating relative positional relationships and do not represent actual scale.

[0047] It should be noted that specific details are set forth in the following description to facilitate understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0048] The following explains the terminology that may appear in the embodiments of this application.

[0049] Radiator (or antenna stub): This is the device in an antenna used to receive / transmit electromagnetic waves. In some cases, the term "antenna" is narrowly defined as the radiator, which converts guided wave energy from the transmitter into radio waves, or converts radio waves into guided wave energy, for radiating and receiving radio waves. The modulated high-frequency current energy (or guided wave energy) generated by the transmitter is transmitted to the transmitting radiator via a feed line, where it is converted into electromagnetic wave energy of a specific polarization and radiated in the desired direction. The receiving radiator converts the electromagnetic wave energy of a specific polarization from a specific direction in space back into modulated high-frequency current energy, which is then delivered to the receiver input via a feed line.

[0050] Radiators (or antenna stubs) may include conductors with specific shapes and sizes, such as wires or sheets, and this application does not limit the specific shape. In one embodiment, a linear radiator may be simply referred to as a wire antenna. In one embodiment, a linear radiator may be implemented by a conductive frame, and may also be called a frame antenna. In one embodiment, a linear radiator may be implemented by a support conductor, and may also be called a support antenna. In one embodiment, the wire diameter (e.g., including thickness and width) of the linear radiator, or the radiator of the wire antenna, is much smaller than the wavelength (e.g., the wavelength of the medium) (e.g., less than 1 / 16 of the wavelength), while the electrical length may be comparable to the wavelength (e.g., the wavelength of the medium) (e.g., the electrical length is around 1 / 8 of the wavelength, or 1 / 8 to 1 / 4, or 1 / 4 to 1 / 2, or longer). The main forms of wire antennas include dipole antennas, half-wave dipole antennas, monopole antennas, loop antennas, and inverted F antennas (IFA). For example, in a dipole antenna, each dipole antenna typically includes two radiating stubs, each fed from the feed end of the radiating stub by a feed section. For example, an inverted-F antenna can be considered as a monopole antenna with an added ground path. An inverted-F antenna has one feed point and one ground point, and is called an inverted-F antenna because its side view is inverted-F shaped. In one embodiment, the sheet radiator may include a microstrip antenna or a patch antenna, such as a planar inverted-F antenna (PIFA). In one embodiment, the sheet radiator may be implemented using a planar conductor (e.g., a conductive sheet or conductive coating). In one embodiment, the sheet radiator may include a conductive sheet, such as a copper sheet. In one embodiment, the sheet radiator may include a conductive coating, such as silver paste. The shape of the sheet radiator includes circular, rectangular, and annular shapes, and this application does not limit the specific shape. The structure of a microstrip antenna generally consists of a dielectric substrate, a radiator, and a ground plane, wherein the dielectric substrate is disposed between the radiator and the ground plane.

[0051] Radiators (or antenna stubs) may also include slots or gaps formed on a conductor, for example, closed or semi-closed slots or gaps formed on a grounded conductor surface. In one embodiment, a slotted or slit radiator may be simply referred to as a slot antenna or a gap antenna. In one embodiment, the radial dimension (e.g., including width) of the slot or gap of the slot antenna / gap antenna is much smaller than the wavelength (e.g., the dielectric wavelength) (e.g., less than 1 / 16 of the wavelength), while the electrical length dimension may be comparable to the wavelength (e.g., the dielectric wavelength) (e.g., the electrical length is approximately 1 / 8 of the wavelength, or 1 / 8 to 1 / 4, or 1 / 4 to 1 / 2, or longer). In one embodiment, a radiator with a closed slot or gap may be simply referred to as a closed slot antenna. In one embodiment, a radiator with a semi-closed slot or gap (e.g., an opening added to a closed slot or gap) may be simply referred to as an open slot antenna. In some embodiments, the gap shape is elongated. In some embodiments, the length of the gap is approximately half a wavelength (e.g., the dielectric wavelength). In some embodiments, the length of the gap is approximately an integer multiple of a wavelength (e.g., one dielectric wavelength). In some embodiments, the slot can be fed by transmission lines connected across one or both sides, thereby exciting a radio frequency electromagnetic field on the slot and radiating electromagnetic waves into space. In one embodiment, the radiator of the slot antenna or gap antenna can be implemented by a conductive frame grounded at both ends, also known as a frame antenna; in this embodiment, the slot antenna or gap antenna can be viewed as including a linear radiator, the linear radiator being spaced apart from the ground and grounded at both ends, thereby forming a closed or semi-closed slot or gap. In one embodiment, the radiator of the slot antenna or gap antenna can be implemented by a support conductor grounded at both ends, also known as a support antenna.

[0052] A matching circuit is a circuit associated with adjusting the radiation characteristics of an antenna. In one embodiment, the matching circuit is coupled between the feed circuit and the corresponding radiator. Typically, the matching circuit is coupled between the test mount and the radiator. In one embodiment, the matching circuit has impedance matching and / or frequency tuning functions. It is generally considered part of the antenna.

[0053] A tuning circuit is a circuit associated with adjusting the resonant frequency of an antenna. In one embodiment, the tuning circuit is coupled between the radiator and the ground. In another embodiment, the tuning circuit is coupled between the feed circuit and the radiator. In yet another embodiment, the tuning circuit functions as impedance matching and / or frequency tuning. Typically, it is considered part of the antenna.

[0054] In one embodiment, the matching circuit / tuning circuit may include switches and / or electronic components / devices, where the switches may be electronic components / devices for switching the coupling connection of the radiator. The switches in the matching circuit / tuning circuit may also be referred to as antenna switches. In one embodiment, the matching circuit / tuning circuit may include a filter circuit.

[0055] The grounding / feeding structure may include connectors, such as metal springs, and the radiator is coupled to the ground via the grounding structure and coupled to the feed circuit via the feed structure. In some embodiments, the feed structure may include a transmission line / feed wire, and the grounding structure may include a ground wire.

[0056] A feed line, also called a transmission line, is the connection line between the antenna transceiver and the radiator. Transmission lines can transmit current waves or electromagnetic waves directly, depending on the frequency and type. The connection point on the radiator where the transmission line connects is usually called the feed point. Transmission lines include conductive transmission lines, coaxial transmission lines, waveguides, and microstrip lines. Depending on their implementation, transmission lines can include antenna frames or glass antenna frames. Depending on the carrier, transmission lines can be made of liquid crystal polymer (LCP), flexible printed circuit boards (FPC), or printed circuit boards (PCBs).

[0057] Ground / Plug: This can refer to at least a portion of any grounding layer, ground plane, or grounding metal layer within a mobile terminal (such as a mobile phone), or at least a portion of any combination of the aforementioned grounding layers, ground planes, or grounding components. "Ground / Plug" can be used for grounding components within the mobile terminal, or in other words, can be used as a reference ground for components within the mobile terminal. Typically, large areas / blocks of metal layers within a mobile terminal can serve as "ground / Plug." In one embodiment, "ground / Plug" may include any one or more of the following: a grounding layer of the mobile terminal's circuit board, a ground plane formed by the mobile terminal's mid-frame, a grounding metal layer formed by a thin metal film beneath the screen, a conductive grounding layer of the battery, a metal hinge of a foldable mobile terminal, a metal back cover of the mobile terminal (e.g., when at least a portion of the back cover is metal), and conductive or metal components electrically connected to the aforementioned grounding layer / ground plane / metal layer. In one embodiment, the circuit board may be a printed circuit board (PCB), such as an 8-layer, 10-layer, or 12-to-14-layer board having 8, 10, 12, 13, or 14 layers of conductive material, or components separated and electrically insulated by dielectric or insulating layers such as fiberglass, polymers, etc. In one embodiment, the circuit board includes a dielectric substrate, a ground layer, and a trace layer, the trace layer and the ground layer being electrically connected via vias. In one embodiment, components such as displays, touchscreens, input buttons, transmitters, processors, memory, batteries, charging circuits, and system-on-chip (SoC) devices may be mounted on or connected to the circuit board; or electrically connected to the trace layers and / or ground layers in the circuit board. For example, a radio frequency source is disposed on a trace layer.

[0058] Any of the aforementioned grounding layers, ground planes, or grounding metal layers are made of conductive materials. In one embodiment, the conductive material may be any of the following: copper, aluminum, stainless steel, brass and their alloys, copper foil on an insulating substrate, aluminum foil on an insulating substrate, gold foil on an insulating substrate, silver-plated copper, silver-plated copper foil on an insulating substrate, silver foil on an insulating substrate and tin-plated copper, graphite-impregnated cloth, graphite-coated substrates, copper-plated substrates, brass-plated substrates, and aluminum-plated substrates. Those skilled in the art will understand that grounding layers / ground planes / grounding metal layers may also be made of other conductive materials.

[0059] Grounding: refers to coupling with the aforementioned ground / floor via a grounding structure and / or grounding circuit. In one embodiment, grounding can be achieved through physical grounding, such as through a structural component of the mid-frame to achieve a physical ground (or physical ground) at a specific location on the frame. In another embodiment, grounding can be achieved through device grounding, such as through devices like capacitors / inductors / resistors connected in series or parallel (or device ground).

[0060] Resonant frequency: The resonant frequency is also called the resonance frequency. The resonant frequency can have a frequency range, that is, the frequency range in which resonance occurs. The resonant frequency can be a frequency range where the return loss characteristic is less than -6dB. The point of strongest resonance can be called the resonant point, and the frequency corresponding to the resonant point is the center frequency. The return loss characteristic of the center frequency can be less than -20dB. It should be understood that, unless otherwise specified, when the antenna / radiator in this application generates "first / second...resonance," the first resonance should be the fundamental mode resonance generated by the antenna / radiator, or in other words, the lowest frequency resonance generated by the antenna / radiator. It should be understood that the antenna / radiator can generate one or more antenna modes according to a specific design, and each antenna mode can correspond to a fundamental mode resonance.

[0061] Resonant frequency band: The range of resonant frequencies is the resonant frequency band. The return loss characteristic at any frequency point within the resonant frequency band can be less than -4dB.

[0062] Communication band / operating band: Regardless of the type of antenna, it always operates within a certain frequency range (bandwidth). For example, an antenna that supports the B40 band operates within the frequency range of 2300MHz to 2400MHz, or in other words, the antenna's operating band includes the B40 band.

[0063] The resonant frequency band and the operating frequency band can be the same or can partially overlap. In one embodiment, one or more resonant frequency bands of the antenna can cover one or more operating frequency bands of the antenna.

[0064] Electrical length: Electrical length can be expressed as the ratio of physical length (i.e., mechanical length or geometric length) multiplied by the time it takes for an electrical or electromagnetic signal to travel in a medium to the time required for that signal to travel a distance in free space equal to the physical length of the medium. Electrical length can be expressed by the following formula:

[0065]

[0066] Where L is the physical length, a is the transmission time of the electrical or electromagnetic signal in the medium, and b is the transmission time in free space.

[0067] Alternatively, electrical length can also refer to the ratio of physical length (i.e., mechanical length or geometric length) to the wavelength of the transmitted electromagnetic wave, and electrical length can satisfy the following formula:

[0068]

[0069] Where L is the physical length and λ is the wavelength of the electromagnetic wave.

[0070] In some embodiments of this application, the physical length of the radiator can be understood as falling within ±20%, ±10%, or ±5% of the electrical length of the radiator.

[0071] Wavelength: or operating wavelength, can be the wavelength corresponding to the center frequency of the resonant frequency or the center frequency of the operating frequency band supported by the antenna. For example, assuming the center frequency of the B1 uplink band (resonant frequency from 1920MHz to 1980MHz) is 1955MHz, then the operating wavelength can be the wavelength calculated using this frequency. Not limited to the center frequency, "operating wavelength" can also refer to the wavelength corresponding to the non-center frequency of the resonant frequency or operating frequency band.

[0072] It should be understood that the wavelength of a radiation signal in air can be calculated as follows: (air wavelength, or vacuum wavelength) = speed of light / frequency, where the frequency is the frequency of the radiation signal (MHz), and the speed of light can be taken as 3 × 10⁸ m / s. The wavelength of a radiation signal in a medium can be calculated as follows: Where ε is the relative permittivity of the medium. The wavelength in the embodiments of this application typically refers to the medium wavelength, which can be the medium wavelength corresponding to the center frequency of the resonant frequency, or the medium wavelength corresponding to the center frequency of the operating frequency band supported by the antenna. For example, assuming the center frequency of the B1 uplink band (resonant frequency of 1920MHz to 1980MHz) is 1955MHz, then the wavelength can be the medium wavelength calculated using this frequency. Not limited to the center frequency, the "medium wavelength" can also refer to the medium wavelength corresponding to the non-center frequency of the resonant frequency or operating frequency band. For ease of understanding, the medium wavelength mentioned in the embodiments of this application can be simply calculated using the relative permittivity of the medium filling one or more sides of the radiator.

[0073] End / Point: The term "end / point" in the context of the antenna radiator's first end / second end / feed end / ground end / feed point / ground point / connection point should not be narrowly interpreted as an endpoint or end that is physically disconnected from other radiators. It can also be considered as a point or segment on a continuous radiator. In one embodiment, "end / point" may include a connection / coupling region on the antenna radiator that is coupled to other conductive structures. For example, a feed end / feed point may be a coupling region on the antenna radiator that is coupled to a feed structure (e.g., a region facing a part of the feed structure). Similarly, a ground end / ground point may be a connection / coupling region on the antenna radiator that is coupled to a ground structure.

[0074] Open and Closed Terminals: In some embodiments, open and closed terminals are defined relative to whether or not they are grounded; the closed terminal is grounded, and the open terminal is not grounded. In one embodiment, the open terminal may also be referred to as a floating terminal, a free terminal, an open terminal, or an open-circuit terminal. In one embodiment, the closed terminal may also be referred to as a grounded terminal or a short-circuit terminal. It should be understood that in some embodiments, other conductors can be coupled through the open terminal to transfer coupled energy (which can be understood as transferring current).

[0075] In some embodiments, the open end and the closed end are, for example, relative to other conductors, with the closed end electrically connected to other conductors and the open end not electrically connected to other conductors.

[0076] To put it simply, the "open end" of a radiator can be defined as one end of the radiator that is spaced apart from the floor or coupled to the floor through a capacitive device.

[0077] To put it simply, the "grounding terminal" of a radiator can be understood as: if one end of the radiator is directly connected to the floor or coupled to the floor through an inductive device, it can be regarded as the grounding terminal of the radiator.

[0078] In some embodiments, the understanding of "closed end" can also be from the perspective of current distribution. A closed end or ground end can be understood as a point of high current or low electric field on a radiator. In one embodiment, coupling electronic devices (e.g., inductive devices) through a closed end can maintain the current distribution characteristics of the point of high current / low electric field. In one embodiment, opening a slit at or near the closed end (e.g., filling the slit with insulating material) can maintain the current distribution characteristics of the point of high current / low electric field.

[0079] In some embodiments, the understanding of "open terminal" can also be from the perspective of current distribution. An open terminal or a floating terminal can be understood as a point with a small current or a point with a large electric field on the radiator. In one embodiment, coupling electronic devices (e.g., capacitive devices) through an open terminal can maintain the current distribution characteristics of the point with a small current or a large electric field.

[0080] It should be understood that when an electronic device (e.g., capacitor, inductor, etc.) is coupled at the radiator end of a gap (which, from the perspective of the radiator's structure, resembles a radiator at the opening of an open or suspended end), the radiator end can be a point with a large current / small electric field. In this case, it should be understood that the radiator end at the gap is actually a closed end or a grounded end, etc.

[0081] The current in the same direction / opposite direction mentioned in the embodiments of this application should be understood as the main current on the same side of the conductor being in the same direction / opposite direction. For example, when a current distributed in the same direction is excited on a conductor that is bent or looped (e.g., the current path is also bent or looped), it should be understood that, for example, the main current excited on the conductors on both sides of a looped conductor (e.g., on the conductors on both sides of a gap) is opposite in direction, but it still falls under the definition of current distributed in the same direction in this application. In one embodiment, current in the same direction on a conductor can mean that the current on the conductor has no reversal point. In one embodiment, current in opposite direction on a conductor can mean that the current on the conductor has at least one reversal point. In one embodiment, current in the same direction on two conductors can mean that the current on both conductors has no reversal point and flows in the same direction. In one embodiment, current in opposite direction on two conductors can mean that the current on both conductors has no reversal point and flows in opposite directions. Current in the same direction / opposite direction on multiple conductors can be understood accordingly.

[0082] Relative / Relative Setting: A and B relative setting can refer to A and B being face-to-face. For example, when two radiators are set relative to each other, the two radiators overlap in at least a partial area along a certain direction. In one embodiment, the two relatively set radiators are adjacent to each other and there are no other radiators or conductors other than antenna structures between them.

[0083] Impedance and Impedance Matching: Antenna impedance generally refers to the ratio of voltage to current at the antenna input. Antenna impedance is a measure of the resistance of the antenna to electrical signals. Generally, the input impedance of an antenna is a complex number; the real part is called the input resistance, denoted by Ri; the imaginary part is called the input reactance, denoted by Xi. Antennas with an electrical length much smaller than the operating wavelength have very large input reactances; for example, short dipole antennas have large capacitive reactances, and small-loop antennas have large inductive reactances. The input impedance of a very thin half-wave dipole is approximately 73.1 + j42.5 ohms. In practical applications, for ease of matching, it is generally desirable for the input reactance of a symmetrical dipole to be zero; the length of the dipole in this case is called the resonant length. The length of a resonant half-wave dipole is slightly shorter than half a wavelength in free space; in engineering, it is generally estimated to be shortened by 5%. The input impedance of an antenna is related to factors such as the antenna's geometry, size, feed point location, operating wavelength, and surrounding environment. When the diameter of a wire antenna is relatively large, the input impedance changes more gradually with frequency, and the antenna's impedance bandwidth is wider.

[0084] The primary purpose of studying antenna impedance is to achieve matching between the antenna and the transmission line. To match the transmitting antenna to the transmission line, the antenna's input impedance should equal the characteristic impedance of the transmission line. To match the receiving antenna to the receiver, the antenna's input impedance should equal the complex conjugate of the load impedance. Receivers typically have real impedances. When the antenna impedance is complex, a matching network is needed to eliminate the reactive portion of the antenna and equalize its resistive portion.

[0085] When the antenna and transmission line are matched, the power transmitted from the transmitter to the antenna or from the antenna to the receiver is at its maximum. At this point, no reflected waves appear on the transmission line, the reflection coefficient is zero, and the standing wave ratio (VSWR) is 1. The quality of the antenna-transmission line matching is measured by the reflection coefficient or VSWR at the antenna input. For a transmitting antenna, poor matching will reduce the antenna's radiated power, increase losses on the transmission line, and decrease the transmission line's power capacity. In severe cases, it can even cause transmitter frequency "pulling," meaning a change in the oscillation frequency.

[0086] Antenna radiation pattern: also known as radiation pattern. It refers to the graph showing how the relative field strength (normalized modulus) of the antenna's radiated field changes with direction at a certain distance from the antenna. It is usually represented by two mutually perpendicular planar radiation patterns passing through the direction of maximum radiation of the antenna.

[0087] Radiation efficiency refers to the ratio of the power radiated by an antenna into space (i.e., the power effectively converted into electromagnetic waves) to the active power input to the antenna. The active power input to the antenna equals the antenna's input power minus the power loss. Power loss mainly includes return loss power, ohmic loss power of the metal, and / or dielectric loss power. Both metal loss and dielectric loss are factors affecting radiation efficiency.

[0088] Those skilled in the art will understand that efficiency is generally expressed as a percentage, and there is a corresponding conversion relationship between it and dB. The closer the efficiency is to 0dB, the better the efficiency of the antenna.

[0089] dB: This stands for decibel, a logarithmic concept with base 10. Decibels are used to evaluate the proportional relationship between two physical quantities; they themselves have no physical dimensions. For every 10-fold increase in the ratio between two quantities, their difference can be expressed as 10 decibels. For example: A = 100, B = 10, C = 5, D = 1, then A / D = 20 dB; B / D = 10 dB; C / D = 7 dB; B / C = 3 dB. In other words, a 10-decibel difference between two quantities is a 10-fold difference, a 20-decibel difference is a 100-fold difference, and so on. A 3-decibel difference is a 2-fold difference between the two quantities.

[0090] dBi: Usually mentioned together with dBd. dBi and dBd are units of power gain, both relative values, but with different reference points. The reference point for dBi is an omnidirectional antenna; the reference point for dBd is a dipole. Generally, dBi and dBd are considered to represent the same gain, but the value expressed in dBi is 2.15 dBi larger than that expressed in dBd. For example, for an antenna with a gain of 16 dBd, its gain converted to dBi is 18.15 dBi, generally ignoring the decimal places, hence 18 dBi.

[0091] To facilitate understanding of the antenna structure provided in this application embodiment, its application scenarios are first introduced below. The antenna structure provided in this application embodiment is applicable to mobile terminals employing one or more of the following communication technologies: Bluetooth (BT) communication technology, Global Positioning System (GPS) communication technology, Wireless Fidelity (WiFi) communication technology, Global System for Mobile Communications (GSM) communication technology, Wideband Code Division Multiple Access (WCDMA) communication technology, Long Term Evolution (LTE) communication technology, 5G communication technology, and other future communication technologies. In this application embodiment, the mobile terminal can be, but is not limited to, any form of mobile terminal such as a candybar phone, foldable phone, multi-folding phone, tablet computer, or smart screen.

[0092] Figure 1 This is a schematic diagram of the structure of a mobile terminal provided in an embodiment of this application, such as... Figure 1 As shown, taking a mobile phone as an example, the mobile terminal 010 may include: a cover 011, a display / module 012, a printed circuit board (PCB) 013, a middle frame 014, and a rear cover 015. It should be understood that in some embodiments, the cover 011 may be a glass cover, or it may be replaced with a cover made of other materials, such as an ultra-thin glass cover, a polyethylene terephthalate (PET) cover, etc.

[0093] The cover plate 011 can be set close to the display screen 012. The cover plate 011 mainly serves to protect and prevent dust from the display screen 012.

[0094] In one embodiment, the display screen 012 may include a liquid crystal display (LCD), a light emitting diode (LED) display panel, or an organic light-emitting diode (OLED) display panel, etc., and this application does not limit it.

[0095] The middle frame 014 mainly serves to support the entire machine. Figure 1 The diagram shows PCB 013 positioned between the middle frame 014 and the back cover 015. It should be understood that in one embodiment, PCB 013 may also be positioned between the middle frame 014 and the display screen 012; this application does not impose any limitations on this. The printed circuit board PCB 013 can be made of flame-retardant material (FR-4) dielectric, or it can be made of Rogers dielectric, or a hybrid dielectric of Rogers and FR-4, etc. Here, FR-4 is a designation for a flame-retardant material grade, and Rogers dielectric is a high-frequency board. Electronic components, such as radio frequency chips, are mounted on PCB 013.

[0096] The mobile terminal 010 may also include a battery (not shown in the figure). The battery may be disposed between the middle frame 014 and the back cover 015, or between the middle frame 014 and the display screen 012, and this application does not limit this. In some embodiments, the PCB 013 is divided into a motherboard and a daughterboard, and the battery may also be disposed between the motherboard and the daughterboard, wherein the motherboard may be disposed between the middle frame 014 and the upper edge of the battery, and the daughterboard may be disposed between the middle frame 014 and the lower edge of the battery.

[0097] The mobile terminal 010 may also include a frame 016, which may be formed of a conductive material such as metal. The frame 016 may be connected between the display screen 012 and the back cover 015, and the frame 016 is arranged circumferentially around the periphery of the mobile terminal 010. In addition, in this application, the frame 016 may have four sides surrounding the display screen 015 for fixing the display screen 015.

[0098] In one implementation, the frame 016, primarily composed of conductive material, can be referred to as the conductive frame or metal frame of the mobile terminal 010, suitable for industrial design (ID). In another implementation, the outer surface of the frame 016 is primarily made of conductive material, such as metal, thus forming the appearance of a metal frame. In these implementations, the conductive portion of the outer surface of the frame 016 can be used as an antenna radiator of the mobile terminal 010, and is commonly referred to as a frame antenna.

[0099] In another implementation, the outer surface of the frame 016 is primarily made of a non-conductive material, such as plastic, to create the appearance of a non-metallic frame, suitable for non-metallic IDs. In another implementation, the inner surface of the frame 016 may include a conductive material, such as a metallic material. In this implementation, the inner surface of the frame 016 can be used as an antenna radiator for the mobile terminal 010. It should be understood that the radiator (or the conductive material of the inner surface) disposed on the inner surface of the frame 016 can be positioned close to the non-conductive material of the frame 016 to minimize the internal space occupied by the radiator in the mobile terminal 010 and to bring the radiator closer to the outside of the mobile terminal 010, thereby achieving better signal transmission performance, and can also be referred to as a frame antenna. It should be noted that, in this application, the setting of the antenna radiator against the non-conductive material of the frame 016 means that the antenna radiator can be set tightly against the inner surface of the non-conductive material of the frame 016, for example, the antenna radiator is set on one side of the frame 016; in addition, the setting of the antenna radiator against the non-conductive material of the frame 016 can also mean that the antenna radiator is embedded inside the non-conductive material; or, the setting of the antenna radiator against the non-conductive material of the frame 016 can also mean that the antenna radiator is close to the inner surface of the non-conductive material, for example, there is a certain small gap between the antenna radiator and the inner surface of the non-conductive material. It should be understood that both the aforementioned conductive material and the non-conductive material can be regarded as part of the frame 016.

[0100] In this application, the middle frame 014 may include a border 016. The middle frame 014, including the border 016, acts as a single unit, supporting the electronic components within the device. The cover plate 011 and the rear cover 015 are respectively fitted along both sides of the border 016 to form the outer shell or housing of the mobile terminal 010. Alternatively, in this application, the border 016 may not be considered part of the middle frame 014. That is, in one embodiment of this application, the border 016 can be connected to and integrally formed with the middle frame 014. In another embodiment of this application, the border 016 may include a protrusion extending into the interior of the mobile terminal 010 for connection with the middle frame 014. The protrusion of the border 016 and the middle frame 014 may be connected by, but not limited to, spring clips, screws, welding, etc. Furthermore, in one embodiment, the cover plate 011, the rear cover 015, the border 016, and the middle frame 014 can be collectively referred to as the outer shell or housing of the mobile terminal 010. It should be understood that "outer shell or housing" can be used to refer to part or all of any one of the cover plate 011, back cover 015, frame 016 or middle frame 014, or to part or all of any combination of the cover plate 011, back cover 015, frame 016 or middle frame 014.

[0101] In this application, the back cover 015 can be a back cover made of metal; it can also be a back cover made of non-conductive material, such as a glass back cover, a plastic back cover, or other non-metallic back covers; or it can be a back cover that includes both conductive and non-conductive materials.

[0102] In one embodiment, a back cover 015, which includes conductive material, can replace the middle frame 014 and be integrated with the frame 016 as a single piece to support the electronic components in the device.

[0103] In one embodiment, the conductive portions in the mid-frame 014 and / or the back cover 015 can serve as a reference ground for the mobile terminal 010, wherein the frame 016 and PCB 013 of the mobile terminal, etc., can be grounded by being electrically connected to the mid-frame 014.

[0104] In one embodiment, the frame 016 can at least partially function as an antenna radiator to transmit / receive radio frequency signals. This portion of the frame serving as the radiator may have gaps between itself and other parts of the middle frame 014, or between itself and the middle frame 014, thereby ensuring a good radiation environment for the antenna radiator. In one embodiment, an aperture may be provided near this portion of the frame serving as the antenna radiator. In one embodiment, the aperture may include an aperture disposed inside the mobile terminal 010, for example, an aperture not visible from the exterior surface of the mobile terminal 010. In one embodiment, the internal aperture may be formed by any one or multiple of the middle frame 014, battery, circuit board, back cover 015, display screen 012, and other internal conductive components; for example, the internal aperture may be formed by a structural component of the middle frame 014. In one embodiment, the aperture may also include a slot / slit / opening on the frame 016. In one embodiment, the slot / slit / opening on the frame 016 may be a slit formed on the frame 016, at which the frame 016 is divided into two parts without a direct connection. In one embodiment, the aperture may further include a slit / gap / hole provided on the back cover 015 or the display screen 012. In one embodiment, the back cover 015 includes a conductive material, and the aperture provided in the conductive material may communicate with the slit or gap of the frame 016 to form a continuous aperture on the surface of the mobile terminal 010.

[0105] In one embodiment, the bezel 016 includes a protrusion extending into the interior of the mobile terminal 010 for connection to other portions of the mid-frame 014, or for connection to the mid-frame 014 (in one embodiment, it may also be integrally formed). In one embodiment, the protrusion includes a conductive material, which also allows the protrusion to receive power signals or connect to a ground plane, so that the corresponding bezel portion can be used to transmit / receive radio frequency signals.

[0106] Figure 1The mobile terminal 010 is shown only schematically; the actual shape, size, and construction of these components are not subject to change. Figure 1 limited.

[0107] It should be understood that in the embodiments of this application, the surface where the display screen 012 of the mobile terminal 010 is located can be considered as the front, the surface where the back cover 015 is located as the back, and the surface where the frame 016 is located as the side.

[0108] It should be understood that, in the embodiments of this application, when a user holds the mobile terminal 010 (for example, when the user holds the mobile terminal 010 and unlocks it, or for example, when the user holds the mobile terminal 010 vertically and faces the screen), the orientation of the mobile terminal 010 has a top, a bottom, and two sides located between the top and the bottom.

[0109] Currently, the antenna used in mobile terminal 010 to operate in low frequency bands is usually called a frame antenna. The frame antenna is usually set on the side of the frame corresponding to the side of the mobile terminal and is located near the bottom of the mobile terminal. The low frequency band may include at least one communication frequency band within 600MHz-1GHz.

[0110] Figure 2 This is a schematic diagram illustrating the existing frame antenna configuration in a mobile terminal. Figure 2 Used to display the rear view of the mobile terminal, that is Figure 2 This shows the placement of the bezel antennas when the back cover of the mobile terminal is facing the user. Figure 2 In the design, the radiator 1 of the frame antenna is disposed on one side of the frame 016, with one end of the radiator 1 being an open end and the other end being a grounded end. Furthermore, the physical length of the radiator 1 of the frame antenna is L1, and the electrical length of the radiator 1 with a physical length of L1 is approximately 1 / 4λ, where λ is the wavelength corresponding to the resonance generated by the frame antenna.

[0111] You can continue to refer to Figure 2 The frame antenna also includes an impedance matching circuit 2, which is connected to the feed point 101 of the radiator 1. The impedance matching circuit 2 includes an inductor ( Figure 2 (Not shown in the image), this inductor is used for impedance matching of the frame antenna to adjust the resonant frequency generated by the frame antenna. Furthermore, the inductance value of the inductor in the impedance matching circuit is relatively large, for example, 15nH.

[0112] Figure 2The frame antenna also includes a tuning circuit 3, one end of which is grounded, and the other end is electrically connected between the impedance matching circuit 2 and the feed point 101. The capacitor in the tuning circuit 3 is used to tune the frequency of the frame antenna, and the capacitance value of the capacitor in the tuning circuit 2 is relatively small, for example, 2pF.

[0113] Figure 3a for Figure 2 The color diagram shows the current distribution of the frame antenna. Additionally, Figure 3b for Figure 3a The grayscale image corresponding to the color current distribution diagram shown is also included. Figure 3a and Figure 3b It can be seen that along the Y direction, that is, along the direction from the open end of radiator 1 to the ground end, the current of the frame antenna gradually increases, and the current at the ground end of the frame antenna is the largest.

[0114] Reference Figure 4a , Figure 4a for Figure 2 The color diagram shows the radiation pattern of the frame antenna in free space. Additionally, Figure 4b for Figure 4a The grayscale image corresponding to the color directional pattern shown is also included. Figure 4a and Figure 4b It can be seen that the above Figure 2 The frame antenna shown has good symmetry in its radiation pattern in free space, indicating high radiation efficiency in free space. Furthermore, in free space, the energy of this frame antenna is mostly radiated towards the back cover of the mobile terminal.

[0115] Reference Figure 5a , Figure 5a for Figure 2 The image shows a color diagram of the radiation pattern of the frame antenna when the mobile terminal is held in the left hand. Additionally, Figure 5b for Figure 5a The grayscale image corresponding to the color directional pattern shown is displayed. By comparison... Figure 4a and Figure 5a or Figure 4b and Figure 5b It can be seen that the above Figure 2 The symmetry of the radiation pattern of the frame antenna shown in the figure is significantly reduced when the device is held in the left hand. This is because when the device is held in the left hand, most of the energy radiated by the frame antenna toward the back cover of the mobile terminal is covered by the left hand, and only a small portion of the energy is radiated toward the display screen.

[0116] Figure 6a for Figure 2 The image shows a color diagram of the radiation pattern of the frame antenna when the mobile terminal is held in the right hand. Additionally, Figure 6b for Figure 6aThe grayscale image corresponding to the color directional pattern shown is displayed. By comparison... Figure 4a and Figure 6a or Figure 4b and Figure 6b It can be seen that the above Figure 2 The symmetry of the radiation pattern of the frame antenna shown in the figure decreases significantly when held in the right hand. This is because when held in the right hand, most of the energy radiated by the frame antenna toward the back cover of the mobile terminal is covered by the right hand, and only a small portion of the energy radiates toward the display screen.

[0117] In summary, while the existing bezel antennas exhibit high radiation efficiency in free space, they suffer from poor grip. This is because the energy radiated by these antennas is primarily directed towards the back cover, with less energy radiated towards the display screen. Therefore, improving the energy radiated by the bezel antenna towards the display screen is crucial for enhancing its grip performance.

[0118] In view of this, this application provides an antenna structure that, by constructing the antenna structure as a co-directional slot antenna, achieves the purpose of making the electric fields generated by each part of the radiator of the antenna structure be in the same direction. This facilitates the tuning of the radiation pattern of the antenna structure towards the display screen side, thereby ensuring the radiation efficiency of the antenna structure in free space while also optimizing the grip performance of the antenna structure. To facilitate understanding of the technical solution of this application, the antenna structure provided by this application will be specifically described below with reference to the accompanying drawings and specific embodiments.

[0119] Reference Figure 7 , Figure 7 This is a simplified structural diagram of a mobile terminal provided in an embodiment of this application. Figure 7 It is also used to display the rear view of a mobile terminal. Additionally, Figure 7 The image illustrates the placement of the antenna structure within a mobile terminal. Specifically, the antenna structure includes a radiator 1, which is positioned on one side of a frame 016. In this application, the radiator 1 may be a conductive portion of the frame 016, such as part of the conductive frame itself, or it may be a conductive element on a non-conductive frame; no limitation is imposed here.

[0120] In the antenna structure provided in this application, the radiator 1 includes a first stub 1a and a second stub 1b connected to each other, wherein the first stub 1a and the second stub 1b are arranged along the direction from the top to the bottom of the mobile terminal. Additionally, the side of the frame 016 used to mount the antenna structure has a slot 0161, and the first stub 1a extends away from the second stub 1b to the aforementioned slot 0161. Therefore, the end of the first stub 1a away from the second stub 1b is an open end, and the end of the second stub 1b away from the first stub 1a is grounded. This application does not limit the grounding method of the end of the second stub 1b away from the first stub 1a; for example, such as... Figure 7 As shown, the mobile terminal also includes a mid-frame 014. The end of the second branch 1b facing away from the first branch 1a can be connected to the mid-frame 014 to achieve grounding through the grounding structure of the mid-frame 014. Alternatively, when the frame 016 and the mid-frame 014 are integrally formed or when the frame 016 and the mid-frame 014 are connected through an inductive component, the end of the second branch 1b facing away from the first branch 1a can be grounded through the portion of the frame 016 used for connection to the mid-frame 014.

[0121] The above is merely an exemplary description of the grounding method of the end of the second branch 1b of the radiator 1 that is away from the first branch 1a. In other possible embodiments of this application, the end of the second branch 1b that is away from the first branch 1a can be connected to the ground in any possible way. They will not be listed one by one here, but they should all be understood to fall within the protection scope of this application.

[0122] It is worth mentioning that, in this application, there should be a clearance between the radiator 1 and the ground in the mobile terminal. The clearance refers to the vertical distance between the radiator and the ground. In antenna structures, the size of the clearance directly affects the signal transmission quality and coverage. Generally, the larger the clearance, the less obstruction the signal experiences, and the better the transmission quality.

[0123] As described above regarding the ground in a mobile terminal, the middle frame 014 can serve as ground. Therefore, in one embodiment of this application, there is a clear space gap between the radiator 1 and the middle frame 014. Furthermore, the radiator 1 must also have a clear space gap with other structures within the mobile terminal used for grounding components, to ensure that the radiator 1 has a good radiation environment.

[0124] You can continue to refer to Figure 7 The first branch 1a includes a power supply point 101, wherein the distance d between the power supply point 101 and the end of the first branch 1a that is away from the second branch 1b satisfies: d≤1 / 4×L1, and d can be 1 / 16L1 or 1 / 8L1, etc.

[0125] In addition, in this application, the antenna structure also includes an impedance matching circuit 2, which is connected to the feed point 101, and the impedance matching circuit 2 includes an inductor 201 and a capacitor ( Figure 7 (not shown in the image) and resistance ( Figure 7 (not shown in the image). It is worth mentioning that in the antenna structure provided in this application, the inductor 201 in the impedance matching circuit 2 is used to perform impedance matching on the antenna structure, thereby achieving the purpose of adjusting the resonant frequency generated by the antenna structure.

[0126] The inductance mentioned in the embodiments of this application can be understood as lumped inductance and / or distributed inductance. Lumped inductance refers to inductive components, such as inductor elements; distributed inductance (or distributed inductance) refers to the equivalent inductance formed through a conductive element of a certain length, such as the equivalent inductance formed by a conductor due to curling or rotation.

[0127] In one possible embodiment of this application, the inductance value of inductor 201 in impedance matching circuit 2 is greater than or equal to 15nH to meet the impedance matching requirements of the antenna structure.

[0128] In addition, in this application, the electrical length λ1 of the first branch 1a is controlled to satisfy: 1 / 4×λ≤λ1<3 / 8×λ. For example, λ1 can be 1 / 4λ to 5 / 16λ, etc., where λ is the wavelength corresponding to the resonance generated by the antenna structure. This is beneficial for the antenna structure to generate an antenna mode similar to a slot antenna.

[0129] It is understood that, since the radiator 1 of the antenna structure provided in this application includes a first stub 1a and a second stub 1b, and the electrical length of the first stub 1a is substantially the same as described above... Figure 2 The electrical length of the entire radiating element 1 of the frame antenna shown is therefore, in relation to the above... Figure 2 Compared to the frame antenna shown, the radiator 1 of the antenna structure provided in this application has a larger electrical length, which is beneficial for increasing the aperture of the antenna structure and thus improving the radiation performance of the antenna structure.

[0130] You can continue to refer to Figure 7 In this application, the connection point between the first branch 1a and the second branch 1b is grounded through an inductive structure. The inductive structure can be an inductor or a distributed inductor.

[0131] In addition, the physical length L1 of the first stub 1a and the physical length L2 of the second stub 1b satisfy the following condition: 4 / 5 ≤ L1 / L2 ≤ 4 / 3. That is to say, the physical length L1 of the first stub 1a and the physical length L2 of the second stub 1b are close. Thus, the antenna structure can be constructed in an antenna pattern analogous to a slot antenna, which is beneficial for optimizing the hand grip performance of the antenna structure.

[0132] It is worth mentioning that when the physical length L1 of the first stub 1a and the physical length L2 of the second stub 1b are close, their corresponding electrical lengths are also close. In one possible embodiment of this application, the electrical length λ1 of the first stub 1a and the electrical length λ2 of the second stub 1b satisfy: |λ1-λ2|≤1 / 16×λ, where λ is the wavelength corresponding to the resonance generated by the antenna structure. In a specific embodiment of this application, the electrical length λ1 of the first stub 1a and the electrical length λ2 of the second stub 1b may be equal.

[0133] In one specific embodiment, the physical length L1 of the first branch 1a and the physical length L2 of the second branch 1b can be equal. (Refer to...) Figure 8a , Figure 8a for Figure 7 A color diagram illustrating the current flow of the antenna structure shown. Additionally, Figure 8b for Figure 8a The grayscale image corresponding to the color diagram of the current flow shown is also included. Figure 8a and Figure 8b It can be seen that the current in the first branch 1a flows in the same direction as the current in the second branch 1b. That is, the current in the first branch 1a flows along the open end toward the connection point of the first branch 1a and the second branch 1b, and the current in the second branch 1b flows along the connection point of the first branch 1a and the second branch 1b toward the grounding end of the second branch 1b.

[0134] Additionally, refer to Figure 9 , Figure 9 for Figure 7 The diagram shows the current amplitude distribution of the antenna structure. Figure 9 The dashed lines in the diagram illustrate the changes in current amplitude on the first branch 1a and the second branch 1b. Figure 9 It can be seen that the amplitude of the current in the first branch 1a has a similar trend to the amplitude of the current in the second branch 1b. That is, along the direction of current flow, the amplitude of the current in the first branch 1a gradually increases, and the amplitude of the current in the second branch 1b gradually increases.

[0135] Figure 10a A color illustration of the electric field distribution of the antenna structure shown in Figure 7. Additionally, refer to... Figure 10b , Figure 10b for Figure 10a The grayscale image corresponding to the color diagram of the electric field distribution shown is also included. Figure 10a and Figure 10b It can be seen that the electric field generated by the first stub 1a is in the same direction as the electric field generated by the second stub 1b, both along a direction perpendicular to the frame 016 and pointing outwards from the mobile terminal. This is beneficial for tuning the antenna structure's radiation pattern in front of the screen when held in hand, thus optimizing the antenna structure's hand-held performance.

[0136] Since the antenna structure provided in this application is designed to operate in a low-frequency band, and the low-frequency band includes at least one communication frequency band within the range of 600MHz-1GHz, in order to switch between the various communication frequency bands within the aforementioned low-frequency band so that the antenna structure can operate in the corresponding communication frequency band, such as... Figure 7 As shown, the antenna structure provided in this embodiment may further include a tuning circuit 3. One end of the tuning circuit 3 is grounded, while the other end is electrically connected between the impedance matching circuit 2 and the feed point 101. Additionally, the tuning circuit 3 includes at least one capacitor 301, which can be used for frequency tuning. That is, when the corresponding capacitor is electrically connected between the impedance matching circuit and the feed point, the antenna structure can operate in the corresponding communication frequency band.

[0137] The capacitors mentioned in the embodiments of this application can be understood as lumped capacitance and / or distributed capacitance. Lumped capacitance refers to capacitive components, such as capacitor elements; distributed capacitance (or distributed capacitance) refers to the equivalent capacitance formed by two conductive components separated by a certain gap. Lumped capacitance may include an immutable capacitor C1 and / or a variable capacitor VAC; distributed capacitance may include interdigitated capacitors and / or other forms of distributed capacitance.

[0138] In this application, the capacitance value of at least one capacitor 301 in the tuning circuit 3 is less than or equal to 2pF. For example, the capacitance value of at least one capacitor 301 in the tuning circuit 3 is 1pF or 2pF. This is beneficial for the antenna structure to generate an antenna pattern similar to a slot antenna.

[0139] In one specific embodiment of this application, the capacitance value of each capacitor in the tuning circuit 3 is less than or equal to 2pF. This can improve the screen radiation pattern of the tuned antenna structure when held in hand, thereby optimizing the hand-held performance of the antenna structure.

[0140] It is understood that in this application, when the tuning circuit 3 includes multiple capacitors 301, these multiple capacitors 301 are connected in parallel. In this way, by electrically connecting different capacitors 301 between the impedance matching circuit 2 and the feed point 101, the communication frequency band of the antenna structure in the low-frequency band can be switched.

[0141] The above only describes some components of the antenna structure provided in this application. In addition, the antenna structure also includes a feeding circuit. Figure 7 (not shown in the image), wherein the impedance matching circuit 2 is electrically connected between the power supply circuit and the power supply point 101.

[0142] In this application, the feed circuit (also called the power supply) is a combination of all circuits used for receiving and transmitting radio frequency (RF) signals. The feed circuit may include a transceiver and an RF front-end. In some cases, the term "feed circuit" is narrowly interpreted as a radio frequency integrated circuit (RFIC), which can be considered to include both the RF front-end chip and the transceiver. The feed circuit has the function of converting radio waves (e.g., RF signals) into electrical signals (e.g., digital signals). It is generally considered part of the RF component.

[0143] In some embodiments, the mobile terminal may also include a test socket (or RF socket or RF test socket). This test socket can be used to insert a coaxial cable to test the characteristics of the RF front-end circuitry or the radiator of the antenna. The RF front-end circuitry can be considered as the circuitry coupled between the test socket and the transceiver.

[0144] In some embodiments, the radio frequency front-end circuit can be integrated into a radio frequency front-end chip in the mobile terminal, or the radio frequency front-end circuit and the transceiver can be integrated into a radio frequency chip in the mobile terminal.

[0145] It should be understood that any two feed circuits in the first / second / ...Nth feed circuit of this application can share the same transceiver, for example, by transmitting signals through a radio frequency channel (e.g., a port (pin) of a radio frequency chip) in a transceiver; they can also share a radio frequency front-end circuit, for example, by processing signals through a switch or amplifier in a radio frequency front-end.

[0146] It should also be understood that the two feed circuits in the first / second / ...Nth feed circuit of this application typically correspond to two RF test sockets in a mobile terminal.

[0147] As described above in this application regarding the specific arrangement of the antenna structure, the connection point between the first stub 1a and the second stub 1b is grounded through the inductive structure 4. This application does not limit the specific grounding method of the inductive structure 4. For example, the inductive structure 4 is connected to the middle frame 014, thereby connecting the connection point between the first stub and the second stub to the middle frame 014 through the inductive structure 4.

[0148] Additionally, you can continue to refer to Figure 7 Since the antenna structure provided in this application operates in the low-frequency band, the antenna structure is located near the bottom of the mobile terminal. Furthermore, since the battery is typically located near the bottom of the mobile terminal, and the battery is housed in the battery compartment 0141 of the mid-frame 014, it can be concluded that the battery compartment 0141 of the mid-frame 014 is located near the bottom of the mobile terminal.

[0149] like Figure 7 As shown, in one possible embodiment of this application, the radiator 1 of the antenna structure is located on one side of the frame 016 facing the battery compartment 0141. Furthermore, along the direction from the second branch 1b to the first branch 1a, the connection point of the first branch 1a and the second branch 1b is lower than the top of the battery compartment 0141. This facilitates improved utilization of the portion of the frame 016 opposite to the battery compartment 0141 and increases the physical length of the radiator 1, thereby increasing the aperture of the antenna structure.

[0150] In one possible embodiment of this application, along the direction from the second branch 1b to the first branch 1a, the open end of the first branch 1a can be made lower than the top of the battery compartment 0141, so that the portion of the frame 016 that is disposed opposite to the battery compartment 0141 can be fully utilized, and the effect of expanding the aperture of the antenna structure can still be achieved.

[0151] Since the battery compartment 0141 can also be a grounding structure, in this application, the inductive structure 4 can include a grounding rib 401. One end of the grounding rib 401 is connected to the connection point of the first branch 1a and the second branch 1b, and the other end of the grounding rib 401 is connected to the battery compartment 0141, that is, the other end of the grounding rib 401 is connected to the middle frame 014.

[0152] This application does not limit the specific arrangement of the grounding tie 401. An exemplary embodiment could be a section of bent strip conductor, such as a strip metal conductor. Furthermore, the grounding tie 401 can be either a rigid structural component or a flexible structural component.

[0153] Furthermore, it is understandable that to ensure battery capacity, the battery volume is usually large, resulting in a larger size for the battery compartment 0141. This leads to a smaller space between the battery compartment 0141 and the side of the frame 016. Therefore, in one possible embodiment of this application, the grounding rib 401 of the inductive structure 4 can be integrally formed with the middle frame 014. This effectively reduces the space occupied by the inductive structure 4, thereby avoiding any impact on the dimensions of the battery compartment 0141.

[0154] It is worth mentioning that, since the frame 016 can also be integrally formed with the middle frame 014, in one possible embodiment of this application, the grounding rib 401 of the inductive structure 4, the middle frame 014 and the frame 016 can be integrally formed. This can ensure the reliability of the connection point of the first branch 1a and the second branch 1b being grounded through the grounding rib 401, and it is also conducive to improving the structural integration of the mobile terminal. In addition, it is also convenient to control the space occupied by the grounding rib 401, so as to reserve enough space for the battery and thus meet the battery capacity requirements.

[0155] In another possible embodiment of this application, the inductive structure 4 may also be a separate structural component. For example, the inductive structure 4 may include a printed circuit board (PCB) and at least two conductive connections, wherein the at least two conductive connections are connected by metal traces on the PCB, thereby enabling at least one conductive connection to be connected to the connection point of the first branch 1a and the second branch 1b, and enabling at least one conductive connection to be connected to the battery compartment 0141.

[0156] In another possible embodiment of this application, the inductive structure 4 may also include a flexible printed circuit (FPC), which can be flexibly bent and disposed between the frame 016 and the battery compartment 0141. In addition, one end of the flexible circuit can be connected to the connection point of the first branch 1a and the second branch 1b, and the other end of the flexible circuit can be connected to the battery compartment 0141.

[0157] The above is just an example of how the sensory structure 4 is set. Based on this, the specific setting of the sensory structure 4 can be adapted according to the specific application scenario. They will not be listed one by one here, but they should all be understood to fall within the protection scope of this application.

[0158] Figure 11a Color diagrams of the antenna structure provided in embodiments of this application in free space. Additionally, Figure 11b for Figure 11a The grayscale image corresponding to the color directional pattern shown is also included. Figure 11a and Figure 11b It can be seen that the antenna structure provided in this application has good symmetry in its radiation pattern in free space, thus exhibiting high radiation efficiency in free space. Furthermore, in free space, the energy of this antenna structure is primarily radiated towards the display screen of the mobile terminal.

[0159] Figure 12 The antenna structure provided in the embodiments of this application and Figure 2 The diagram shows a comparison of the radiation efficiency of existing frame antennas in free space. The solid line represents the radiation efficiency of the antenna structure provided in this application in free space, and the dashed line represents... Figure 2 The radiation efficiency of the existing frame antenna in free space is shown. Figure 12 It can be seen that the antenna structure provided in the embodiments of this application is similar to... Figure 2 The existing frame antenna shown has a radiation efficiency close to that in free space.

[0160] Additionally, refer to Figure 13 , Figure 13 The antenna structure provided in the embodiments of this application and Figure 2 The diagram shows a comparison of the radiation efficiency of existing frame antennas when held in hand. The solid line represents the radiation efficiency of the antenna structure provided in this application when held in hand, and the dashed line represents... Figure 2 The radiation efficiency of the existing frame antenna shown is in a hand-held position. Figure 13 It can be seen that, when held in hand, the radiation efficiency of the antenna structure provided in this embodiment is higher than that of the standard antenna. Figure 2 The radiation efficiency of the existing frame antenna is shown.

[0161] In summary, this application constructs an antenna structure similar to a co-directional slot antenna, ensuring that the currents in the first stub 1a and the second stub 1b of the radiator are in the same direction, thereby ensuring that the electric fields of the first stub 1a and the second stub 1b are in the same direction. This facilitates tuning the antenna structure's radiation pattern in front of the screen when held in hand, thus optimizing the antenna structure's hand-holding performance.

[0162] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A mobile terminal, comprising a frame and an antenna structure, the frame being circumferentially disposed around the periphery of the mobile terminal, the antenna structure comprising a radiator and an impedance matching circuit, the radiator being disposed on one side of the frame, characterized in that, The radiator includes a first branch and a second branch connected together. The end of the first branch away from the second branch is an open end. The first branch includes a feed point. The end of the second branch away from the first branch is grounded. The connection point between the first branch and the second branch is grounded through an inductive structure. The currents in the first branch and the second branch are in the same direction. The physical length L1 of the first branch and the physical length L2 of the second branch satisfy the following condition: 4 / 5 ≤ L1 / L2 ≤ 4 / 3; The distance d between the feed point and the end of the first branch away from the second branch satisfies: d≤1 / 4×L1; The impedance matching circuit is electrically connected to the feed point, and the impedance matching circuit includes an inductor connected in series. The sum of the electrical length λ1 of the first stub and the electrical length λ2 of the second stub satisfies: λ1 + λ2 ≥ 1 / 2 × λ, where λ is the wavelength corresponding to the resonance generated by the antenna structure.

2. The mobile terminal as described in claim 1, characterized in that, The antenna structure is designed to operate in low-frequency bands, including at least one communication band within the range of 600MHz to 1GHz.

3. The mobile terminal as described in claim 2, characterized in that, The inductance value of the inductor is greater than or equal to 15nH.

4. The mobile terminal as described in any one of claims 1 to 3, characterized in that, The antenna structure further includes a tuning circuit, one end of which is grounded and the other end of which is electrically connected between the impedance matching circuit and the feed point; the tuning circuit includes at least one capacitor.

5. The mobile terminal as described in claim 4, characterized in that, The capacitance value of the at least one capacitor is less than or equal to 2pF.

6. The mobile terminal as described in claim 4, characterized in that, The tuning circuit includes a plurality of capacitors, which are connected in parallel.

7. The mobile terminal as described in any one of claims 1 to 3, characterized in that, The antenna structure also includes a feeding circuit, and the impedance matching circuit is electrically connected between the feeding circuit and the feeding point.

8. The mobile terminal as described in any one of claims 1 to 3, characterized in that, The mobile terminal also includes a mid-frame, which is located within the area enclosed by the border. The end of the second branch that is away from the first branch is connected to the mid-frame, and the connection point between the first branch and the second branch is connected to the mid-frame through the sensory structure.

9. The mobile terminal as described in claim 8, characterized in that, The middle frame includes a battery compartment, and the radiator is located on one side of the frame facing the battery compartment and along the direction from the second branch to the first branch, the connection point of the first branch and the second branch being below the top of the battery compartment.

10. The mobile terminal as described in claim 9, characterized in that, The inductive structure includes a grounding rib located between the battery compartment and the radiator. One end of the grounding rib is connected to the connection point of the first branch and the second branch, and the other end of the grounding rib is connected to the middle frame.

11. The mobile terminal as described in claim 10, characterized in that, The grounding rib, the middle frame, and the side frame are integrally formed.

12. The mobile terminal as described in claim 9, characterized in that, The sensory structure is an independent structural component. The sensory part of the sensory structure is connected to the connection point of the first branch and the second branch, and is also connected to the middle frame.

13. The mobile terminal as described in claim 8, characterized in that, There is a clear space gap between the radiator and the middle frame.

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