CN117394030A

CN117394030A - Antenna assembly and electronic equipment

Info

Publication number: CN117394030A
Application number: CN202311528626.5A
Authority: CN
Inventors: 黄文晖
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2023-11-15
Filing date: 2023-11-15
Publication date: 2024-01-12

Abstract

The application provides an antenna assembly and electronic equipment. The antenna assembly includes a signal source, a reference ground, an antenna radiator, and a first tuning circuit. The antenna radiator comprises a first free end, a first grounding end, a feed point and a first connecting point arranged between the feed point and the first free end. The first ground terminal is electrically connected to the reference ground. The feed point is electrically connected to the signal source. The first connection point is electrically connected to the ground reference through the first tuning circuit. The antenna radiator between the first grounding end and the first free end generates a first resonance mode supporting a first target frequency band under the excitation of a signal source, and the first resonance mode is a 1/4 wavelength mode. The antenna radiator and the first tuning circuit between the first grounding end and the first connecting point generate a second resonance mode supporting the first target frequency band under the excitation of the signal source, and the second resonance mode is a 1/2 wavelength mode. The antenna assembly and the electronic device can give consideration to communication performance and SAR value.

Description

Antenna assembly and electronic equipment

Technical Field

The application relates to the technical field of wireless communication, in particular to an antenna assembly and electronic equipment.

Background

With the release of new standards of the human absorptivity (Specific absorption rate, SAR) of domestic electromagnetic radiation, how to further reduce the SAR value on the premise of ensuring the communication performance becomes a technical problem to be solved.

Disclosure of Invention

The application provides an antenna assembly and electronic equipment capable of further reducing SAR value under the premise of ensuring communication performance.

In one aspect, the present application provides an antenna assembly comprising

A signal source;

a reference ground; a kind of electronic device with high-pressure air-conditioning system

The antenna unit comprises an antenna radiator and a first tuning circuit, wherein the antenna radiator comprises a first free end, a first grounding end, a feed point arranged between the first free end and the first grounding end and a first connection point arranged between the feed point and the first free end, the first grounding end is electrically connected with the reference ground, the feed point is electrically connected with the signal source, the first connection point is electrically connected with the reference ground through the first tuning circuit, the antenna radiator between the first grounding end and the first free end generates a first resonance mode supporting a first target frequency band under the excitation of the signal source, the first resonance mode is a 1/4 wavelength mode, the antenna radiator between the first grounding end and the first connection point generates a second resonance mode supporting the first target frequency band under the excitation of the signal source, and the second resonance mode is a 1/2 wavelength mode.

On the other hand, the application also provides electronic equipment, which comprises a frame, a circuit board and an antenna assembly, wherein an accommodating space is formed by surrounding the frame, the circuit board is arranged in the accommodating space, a signal source, a reference ground and a first tuning circuit are arranged on the circuit board, and an antenna radiator is arranged on the frame.

The antenna assembly comprises a signal source, a reference ground and an antenna unit, wherein the antenna unit comprises an antenna radiator and a first tuning circuit, a first connecting point arranged between a feed point and a first free end of the antenna radiator is electrically connected with the reference ground through the first tuning circuit, a first resonance mode supporting a first target frequency band can be generated between the first grounding end and the first free end of the antenna radiator under the excitation of the signal source, a second resonance mode supporting the first target frequency band can be generated between the first grounding end and the first connecting point of the antenna radiator and by the first tuning circuit under the excitation of the signal source, so that a plurality of current strong points formed by the first resonance mode and the second resonance mode exist on the antenna radiator, the first resonance mode is a 1/4 wavelength mode, the second resonance mode is a 1/2 wavelength mode, and therefore the current strong points are distributed at different positions of the antenna radiator, the current strong points on the antenna radiator are split, and the value can be reduced. In addition, the first resonant mode and the second resonant mode support the first target frequency band at the same time, so that the communication performance is not reduced, i.e. the SAR value is further reduced on the premise of ensuring the communication performance.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below.

Fig. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of an antenna assembly according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of an antenna radiator including a first radiating section and a second radiating section in the antenna assembly shown in fig. 2;

fig. 4 is a schematic structural diagram of an antenna radiator of the antenna assembly shown in fig. 2, having a first resonant current corresponding to a first resonant mode;

fig. 5 is a schematic structural diagram of an antenna radiator of the antenna assembly shown in fig. 2 having a second resonant current corresponding to a second resonant mode;

fig. 6 is a schematic diagram of a first tuning circuit of the antenna assembly shown in fig. 2, including an inductor;

fig. 7 is a schematic structural diagram of the antenna assembly shown in fig. 6 further including a matching circuit;

FIG. 8 is a schematic diagram of the antenna assembly of FIG. 7 showing the length of the antenna radiator between the first connection point and the first free end, the length of the antenna radiator between the first free end and the first ground end, and the length of the antenna radiator between the feed point and the first ground end;

Fig. 9 is a schematic structural diagram of a second resonant mode of the antenna assembly shown in fig. 7 forming a second current weak point at a target point;

fig. 10 is a schematic diagram of current intensity variation of a first resonant mode and a second resonant mode of an antenna assembly according to an embodiment of the present disclosure;

fig. 11 is a schematic structural diagram of three antenna assemblies according to an embodiment of the present disclosure;

fig. 12 is a graph of return loss for the three antenna assemblies shown in fig. 11;

FIG. 13 is a simulation diagram of current distribution corresponding to a portion of the three antenna elements shown in FIG. 11;

fig. 14 is a schematic diagram of the antenna assembly shown in fig. 7 further including a parasitic element, the parasitic element including a parasitic stub and a second tuning circuit;

fig. 15 is a schematic structural diagram of the antenna assembly shown in fig. 14, having a third resonant current corresponding to a third resonant mode on a parasitic branch;

fig. 16 is a schematic structural diagram of the antenna assembly shown in fig. 14 with a fourth resonant current corresponding to a fourth resonant mode on a parasitic branch;

fig. 17 is a schematic diagram of a second tuning circuit of the antenna assembly of fig. 14 including an inductor;

fig. 18 is a schematic diagram of the antenna assembly of fig. 17 illustrating the length of the parasitic branch between the second connection point and the second free end, and the length of the parasitic branch between the second free end and the second ground end.

Detailed Description

The technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings. It is apparent that the embodiments described herein are only some examples and not all. All other embodiments obtained by those of ordinary skill in the art based on the embodiments provided herein without undue burden are within the scope of the present application.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

The terms first, second and the like in the description and in the claims of the present application and in the description of the figures above are used for distinguishing between different objects and not for describing a particular sequential order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example: an assembly or device incorporating one or more components is not limited to the listed one or more components, but may alternatively include one or more components not listed but inherent to the illustrated product, or one or more components that may be provided based on the illustrated functionality.

The terms "end" and "point" in the description and claims of the present application and the above description of the drawings may refer to a small section of a body with respect to the entirety of the corresponding body, or to a corresponding port, i.e., the "end" is not to be interpreted as an end in a narrow sense, and the "point" is not to be interpreted as a point in a narrow sense.

Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of an electronic device 1000 according to an embodiment of the present application, and fig. 2 is a schematic structural diagram of an antenna assembly 100 according to an embodiment of the present application. The electronic device 1000 may be a device having wireless communication functions such as a cell phone, tablet, watch, etc. In the embodiment of the present application, a mobile phone is taken as an example. The electronic device 1000 includes a bezel 300, a circuit board 200, and an antenna assembly 100. The antenna assembly 100 includes a signal source 10, a reference ground 11, and an antenna element 12.

The material of the frame 300 may include one or more of metal, alloy, plastic, ceramic, glass, etc. The frame 300 encloses a receiving space 34. In one possible embodiment, the bezel 300 includes a first sub-bezel 30, a second sub-bezel 31, a third sub-bezel 32, and a fourth sub-bezel 33 that are connected end to end in sequence. The first sub-frame 30 is disposed opposite the third sub-frame 32. The second sub-frame 31 is disposed opposite to the fourth sub-frame 33. The bending connection manner between the first sub-frame 30 and the second sub-frame 31, between the second sub-frame 31 and the third sub-frame 32, between the third sub-frame 32 and the fourth sub-frame 33, and between the fourth sub-frame 33 and the first sub-frame 30 is not particularly limited. For example: the first sub-frame 30 and the second sub-frame 31, the second sub-frame 31 and the third sub-frame 32, the third sub-frame 32 and the fourth sub-frame 33 and the first sub-frame 30 may be bent in a right angle shape, or the first sub-frame 30 and the second sub-frame 31, the second sub-frame 31 and the third sub-frame 32, the third sub-frame 32 and the fourth sub-frame 33 and the first sub-frame 30 may be bent in a circular arc shape. The first sub-frame 30, the second sub-frame 31, the third sub-frame 32 and the fourth sub-frame 33 form an accommodating space 34 therebetween. The circuit board 200, the antenna assembly 100, and the like can be accommodated in the accommodation space 34.

The circuit board 200 may include a primary circuit board and/or a secondary circuit board of the electronic device 1000. The circuit board 200 is disposed in the accommodating space 34. When divided by the number of structural layers, the circuit board 200 may be one of a single-sided circuit board, a double-sided circuit board, and a multi-layered circuit board. When divided by bending characteristics, the circuit board 200 may be one of a flexible circuit board, a hard circuit board, and a soft and hard combined board. When divided in a molding process, the circuit board 200 may be one of a printed circuit board (Printed Circuit Boards, PCB), a flexible printed circuit board (Flexible Printed Circuit, FPC), a laser circuit board (Laser Direct Structuring, LDS), and the like. The circuit board 200 includes a ground plane.

The signal source 10 provides an excitation signal to the antenna element 12. The signal source 10 may include a transceiver, and may also include a transceiver and a radio frequency front end module. Wherein the transceiver comprises a transmitter and a receiver. The transceiver is capable of transmitting and receiving radio frequency signals. The rf front-end module is electrically connected between the transceiver and the antenna unit 12, and is capable of performing power amplification on the rf signal transmitted between the transceiver and the antenna unit 12, filtering out spurious signals, and the like. The signal source 10 is disposed on the circuit board 200.

The reference potential of the reference ground 11 is zero. Specifically, the reference ground 11 refers to a ground portion of the electronic device 1000 that is not affected by any ground configuration and is considered to be conductive. The potential convention of reference ground 11 is zero. For example: the reference ground 11 may include a ground layer of a main circuit board, a ground layer of a sub-circuit board, a metal piece of a middle frame, and a conductive piece electrically connecting one or more of the ground layer of the main circuit board, the ground layer of the sub-circuit board, the metal piece of the middle frame, etc. in the electronic device 1000. The ground 11 is referred to in the following embodiments by taking the ground layer of the circuit board 200 as an example. In other words, the reference ground 11 is disposed on the circuit board 200.

The antenna unit 12 includes an antenna radiator 120 and a first tuning circuit 121. The antenna radiator 120 is provided to the frame 300. Alternatively, the antenna radiator 120 may be provided on the inner surface of the bezel 300, or the antenna radiator 120 may be integrated on the bezel 300, or the antenna radiator 120 may be provided on the outer surface of the bezel 300. In other words, the antenna radiator 120 may be an internal antenna radiator, or the antenna radiator 120 may be a metal middle frame antenna radiator, or the antenna radiator 120 may be an external antenna radiator. In the following embodiments, the antenna radiator 120 is exemplified by a metal center antenna radiator unless explicitly described. The material of the antenna radiator 120 may include at least one conductive material such as metal, alloy, carbon fiber, etc. The first tuning circuit 121 may include a capacitance and/or an inductance, etc. The number of capacitors and the number of inductors included in the first tuning circuit 121 are not particularly limited. When the first tuning circuit 121 includes a plurality of capacitors, the plurality of capacitors may be connected in series or in parallel. When the first tuning circuit 121 includes a plurality of inductors, the plurality of inductors may be connected in series or in parallel. When the first tuning circuit 121 includes one or more capacitors and one or more inductors, the inductors and the capacitors may be connected in series or in parallel. The first tuning circuit 121, which may be inductive or capacitive, may be matched accordingly depending on the frequency band supported by the antenna radiator 120. The first tuning circuit 121 is disposed on the circuit board 200.

The antenna radiator 120 includes a first free end a, a first ground end B, a feeding point C disposed between the first free end a and the first ground end B, and a first connection point D disposed between the feeding point C and the first free end a. The first free end a may be understood as an end of the antenna radiator 120 that is not electrically connected to the conductive member or is provided with a break between the conductive member and the conductive member. The first ground terminal B may be understood as an end or port of the antenna radiator 120 electrically connected to the reference ground 11. The feeding point C may be understood as a port of the antenna radiator 120 receiving the excitation signal. The first connection point D may be understood as a port at which the antenna radiator 120 is electrically connected to the first tuning circuit 121.

In one possible embodiment, as shown in fig. 2, the antenna radiator 120 is in a straight line shape, one end of the antenna radiator 120 forms the first free end a, and the other end of the antenna radiator 120 forms the first ground end B. The feeding point C is arranged between the first free end A and the first grounding end B and is spaced from the first free end A and the first grounding end B. The first connection point D may be disposed between the feeding point C and the first free end a, and spaced apart from the feeding point C and the first free end a; alternatively, the first connection point D may be provided at the first free end a.

In the present embodiment, the antenna radiator 120 may be provided at one of the first sub-frame 30, the second sub-frame 31, the third sub-frame 32, and the fourth sub-frame 33.

Of course, in other possible embodiments, as shown in fig. 3, the antenna radiator 120 may include a first radiating section 1201 and a second radiating section 1202 connected in a bent manner, where an end of the first radiating section 1201 away from the second radiating section 1202 may form the first free end a, and an end of the second radiating section 1202 away from the first radiating section 1201 may form the first ground end B. The feeding point C may be provided at the first radiating section 1201 or the second radiating section 1202. When the feeding point C is disposed on the first radiating section 1201, the first connection point D is disposed on the first radiating section 1201; when the feeding point C is disposed in the second radiating section 1202, the first connection point D may be disposed in the first radiating section 1201 or in the second radiating section 1202.

In the present embodiment, the antenna radiator 120 may be provided in two adjacent ones of the first sub-frame 30, the second sub-frame 31, the third sub-frame 32, and the fourth sub-frame 33. For example: one of the first radiation section 1201 and the second radiation section 1202 is arranged on the first sub-frame 30, and the other is arranged on the second sub-frame 31 or the fourth sub-frame 33; alternatively, one of the first radiation section 1201 and the second radiation section 1202 is provided on the third sub-frame 32, and the other is provided on the second sub-frame 31 or the fourth sub-frame 33.

Wherein the feed point C is electrically connected to the signal source 10. The feeding point C may be directly or indirectly electrically connected to the signal source 10. For example: the feeding point C and the signal source 10 may be directly welded, or electrically connected through electrical connectors such as coaxial lines, microstrip lines, conductive elastic sheets, conductive adhesives, etc.

The first ground terminal B is electrically connected to the reference ground 11. The first grounding terminal B may be directly electrically connected to the reference ground 11, or may be indirectly electrically connected to the reference ground. For example: the first grounding end B and the reference ground 11 may be directly welded or electrically connected through electrical connectors such as conductive wires, conductive elastic sheets, conductive adhesives, etc.

The first connection point D is electrically connected to the reference ground 11 through the first tuning circuit 121. In other words, the first tuning circuit 121 is electrically connected between the first connection point D and the reference ground 11. The first tuning circuit 121 may be directly electrically connected to the first connection point D or may be indirectly electrically connected to the first connection point D. For example: the first tuning circuit 121 and the first connection point D may be directly welded, or electrically connected through an electrical connection member such as a conductive wire, a conductive spring, or a conductive adhesive. The first tuning circuit 121 may be directly electrically connected to the reference ground 11 or may be indirectly electrically connected to the reference ground. For example: the first tuning circuit 121 and the reference ground 11 may be directly soldered, or electrically connected through an electrical connection such as a conductive wire, a conductive spring, or a conductive adhesive.

As shown in fig. 4, the antenna radiator 120 between the first ground terminal B and the first free terminal a is configured to generate a first resonant mode supporting the first target frequency band under the excitation of the signal source 10, where the first resonant mode is a 1/4 wavelength mode. It can be appreciated that the first resonant current corresponding to the first resonant mode is distributed between the first ground terminal B and the first free terminal a of the antenna radiator 120. The first resonant current corresponding to the first resonant mode may be referred to as I1 shown in dashed lines in fig. 4. It should be noted that, since the first resonant current is an alternating current, the direction of the first resonant current changes periodically, and thus the direction I1 in the drawing is only one possible flow direction of the first resonant current. The antenna radiator 120 may receive and/or transmit electromagnetic wave signals of a first target frequency band in the first resonant mode.

The first target frequency band is not specifically limited in this application. For example: the first target frequency band may be located in a low frequency (less than or equal to 1 GHz) band; alternatively, the first target frequency band may be located in a medium-high frequency (greater than 1GHz and less than or equal to 3 GHz) frequency band, or the first target frequency band may be located in an ultra-high frequency (greater than 3 GHz) frequency band. The first target frequency band may be a 4G LTE frequency band or a 5G NR frequency band. In the following embodiments, the first target frequency band includes LTE B3 and LTE B1, where not explicitly described. Compared with the frequency band with smaller uplink duty cycle of the actual network such as N41, N78 and the like, the uplink duty cycle of the actual network of LTE B3 and LTE B1 (4G, 1.7 GHz-1.9 GHz) is larger, and the power rollback needs to be considered, so that the technical problem to be solved by the method has greater significance on LTE B3 and LTE B1.

In one possible embodiment, when the antenna radiator 120 between the first ground terminal B and the first free terminal a generates a strong and weak resonant current under the excitation of the signal source 10, and the resonant current generated at the first ground terminal B is relatively strong, and the resonant current generated at the first free terminal a is relatively weak, the antenna radiator 120 between the first ground terminal B and the first free terminal a may be considered to generate a first resonant mode under the excitation of the signal source 10, the first resonant mode being a 1/4 wavelength mode. In other words, the first resonant mode forms a first current strong point at the first ground terminal B, a first current weak point at the first free terminal a, and the current intensity between the first ground terminal B and the first free terminal a gradually decreases.

In another possible embodiment, when the electrical length of the antenna radiator 120 between the first ground terminal B and the first free terminal a is equal to or close to 1/4 wavelength of the first target frequency band, it can be considered that the antenna radiator 120 between the first ground terminal B and the first free terminal a can generate a first resonance mode under the excitation of the signal source 10, the first resonance mode being a 1/4 wavelength mode. Wherein, the electrical length of the antenna radiator 120 between the first ground terminal B and the first free terminal a is equal to k1 PL 1. k1 is the ratio of the transmission time of the electric or electromagnetic wave signal in the first target frequency band in the medium to the transmission time in the free space; PL1 is the physical length of the antenna radiator 120 between the first ground terminal B and the first free terminal a. Taking the example that the first target frequency band includes LTE B3 and LTE B1, the 1/4 wavelength of the first target frequency band may be 35mm to 55mm, that is, when the electrical length of the antenna radiator 120 between the first ground terminal B and the first free terminal a is between 35mm and 55mm, it may be considered that the antenna radiator 120 between the first ground terminal B and the first free terminal a may generate a first resonant mode under the excitation of the signal source 10, and the first resonant mode is a 1/4 wavelength mode.

As shown in fig. 5, the antenna radiator 120 and the first tuning circuit 121 between the first ground terminal B and the first connection point D are configured to generate a second resonance mode supporting the first target frequency band under the excitation of the signal source 10, where the second resonance mode is a 1/2 wavelength mode. It can be understood that the second resonant current corresponding to the second resonant mode is distributed between the first ground B of the antenna radiator 120 and the first connection point D, and the first tuning circuit 121. The second resonant current corresponding to the second resonant mode may be referred to as I2 shown in dashed lines in fig. 5. It should be noted that, since the second resonant current is an alternating current, the direction of the second resonant current changes periodically, and thus the direction I2 in the drawing is only one possible flow direction of the second resonant current. The antenna radiator 120 may receive and/or transmit electromagnetic wave signals of the first target frequency band in the second resonant mode.

Wherein the second resonant mode is concurrent with the first resonant mode. In other words, the first resonant current corresponding to the first resonant mode and the second resonant current corresponding to the second resonant mode are distributed in the antenna radiator 120 at the same time. Since the second resonant mode and the first resonant mode are different wavelength modes, the current intensity point of the second resonant mode is different from the current intensity point of the first resonant mode, so that the current intensity point of the antenna radiator 120 can be dispersed, and the SAR reduction effect is realized.

In one possible implementation, when the antenna radiator 120 between the first ground terminal B and the first connection point D generates a resonant current that is weakened and strengthened by the excitation of the signal source 10, and the resonant current generated at the first ground terminal B and the first connection point D is relatively strong, and there is a current weakness between the first ground terminal B and the first connection point D, the antenna radiator 120 between the first ground terminal B and the first connection point D and the first tuning circuit 121 may be considered to generate a second resonant mode under the excitation of the signal source 10, where the second resonant mode is a 1/2 wavelength mode. In other words, the second resonant mode forms a second current strong point at the first ground terminal B, forms a third current strong point at the first connection point D, and gradually decreases and then gradually increases the current intensity between the first ground terminal B and the first connection point D.

In another possible embodiment, when the sum of the electrical length of the antenna radiator 120 between the first ground terminal B and the first connection point D and the equivalent electrical length of the first tuning circuit 121 is equal to or close to 1/2 wavelength of the first target frequency band, it can be considered that the antenna radiator 120 between the first ground terminal B and the first connection point D and the first tuning circuit 121 can generate a second resonance mode under the excitation of the signal source 10, and the second resonance mode is a 1/2 wavelength mode. Wherein, the electrical length of the antenna radiator 120 between the first ground terminal B and the first connection point D is equal to k1 PL 2. k1 is the ratio of the transmission time of the electric or electromagnetic wave signal in the first target frequency band in the medium to the transmission time in the free space; PL2 is the physical length of the antenna radiator 120 between the first ground terminal B and the first connection point D. Taking the first target frequency band including LTE B3 and LTE B1 as an example, the 1/2 wavelength of the first target frequency band may be 70mm to 110mm, that is, when the sum of the electrical length of the antenna radiator 120 between the first ground terminal B and the first connection point D and the equivalent electrical length of the first tuning circuit 121 is located between 70mm to 110mm, it may be considered that the antenna radiator 120 between the first ground terminal B and the first connection point D and the first tuning circuit 121 may generate the second resonant mode under the excitation of the signal source 10, and the second resonant mode is the 1/2 wavelength mode.

The antenna assembly 100 provided by the application comprises a signal source 10, a reference ground 11 and an antenna unit 12, wherein the antenna unit 12 comprises an antenna radiator 120 and a first tuning circuit 121, since a first connection point D arranged between a feed point C and a first free end A in the antenna radiator 120 is electrically connected with the reference ground 11 through the first tuning circuit 121, a first resonance mode supporting a first target frequency band can be generated between a first grounding end B and the first free end A of the antenna radiator 120 under the excitation of the signal source 10, a second resonance mode supporting the first target frequency band can be generated between the first grounding end B and the first connection point D of the antenna radiator 120 and the first tuning circuit 121 under the excitation of the signal source 10, a plurality of current strong points formed by the first resonance mode and the second resonance mode exist on the antenna radiator 120, the first resonance mode is a 1/4 wavelength mode, the second resonance mode is a 1/2 wavelength mode, and therefore the plurality of current strong points are distributed at different positions of the antenna radiator 120, and the effect of the current strong points on the antenna radiator 120 can be reduced. In addition, the first resonant mode and the second resonant mode support the first target frequency band at the same time, so that the communication performance of the first target frequency band is not reduced, namely, the SAR value is further reduced on the premise of ensuring the communication performance.

As shown in fig. 6, the first tuning circuit 121 is inductive. Optionally, the first tuning circuit 121 includes an inductor; alternatively, the first tuning circuit 121 includes a plurality of inductors connected in series; alternatively still, the first tuning circuit 121 comprises at least one inductance and at least one capacitance, wherein the effect of the inductance is greater than the effect of the capacitance. In one possible implementation, the first tuning circuit 121 includes an inductor. The first tuning circuit 121 is connected in series between the reference ground 11 and the first connection point D of the antenna radiator 120.

The first tuning circuit 121 is inductive, and can correspondingly prolong the electrical length of the antenna radiator 120, which is more beneficial for the antenna radiator 120 between the first grounding end B and the first connection point D, and the first tuning circuit 121 to generate a second resonance mode supporting a low frequency band or a middle-high frequency band under the excitation of the signal source 10, so as to facilitate solving the technical problems that the uplink space occupation of the actual networks such as LTE B3 and LTE B1 is relatively large, and the frequency band needing to consider the power back cannot consider the communication performance and the SAR value.

As shown in fig. 7, the antenna unit 12 further includes a matching circuit 122 electrically connected between the feeding point C and the signal source 10. The matching circuit 122 may be directly or indirectly electrically connected to the feeding point C. For example: the feeding point C and the signal source 10 may be directly welded, or electrically connected through electrical connectors such as conductive wires, conductive spring plates, conductive adhesives, etc. The matching circuit 122 may be directly electrically connected to the signal source 10 or indirectly electrically connected to the signal source. For example: the matching circuit 122 and the signal source 10 may be directly welded, or electrically connected through electrical connectors such as conductive wires, conductive spring plates, conductive adhesives, etc. The matching circuit 122 may include a capacitance and/or an inductance, etc. The number of capacitors and the number of inductors included in the matching circuit 122 are not particularly limited in this application. When the matching circuit 122 includes a plurality of capacitors, the plurality of capacitors may be connected in series or in parallel. When the matching circuit 122 includes a plurality of inductors, the plurality of inductors may be connected in series or in parallel. When the matching circuit 122 includes one or more capacitors, and one or more inductors, the inductors may be connected in series or in parallel with the capacitors. The matching circuit 122 is disposed on the circuit board 200.

Alternatively, the matching circuit 122 may include a capacitor and an inductor in series; alternatively, the matching circuit 122 may also include a capacitor and an inductor connected in parallel; alternatively, the matching circuit 122 may also include an inductor, a first capacitor and a second capacitor, where the inductor is connected in parallel with the first capacitor and then connected in series with the second capacitor; alternatively, the matching circuit 122 may also include a first inductor, a second inductor, and a capacitor, where the first inductor and the capacitor are connected in parallel and then connected in series with the second inductor; alternatively, the matching circuit 122 may also include an inductor, a first capacitor and a second capacitor, where the inductor is connected in series with the first capacitor and then connected in parallel with the second capacitor; alternatively, the matching circuit 122 may also include a first inductor, a second inductor, and a capacitor, where the first inductor is connected in series with the capacitor and then connected in parallel with the second inductor; alternatively, the matching circuit 122 may also include a first matching branch formed by connecting a first inductor and a first capacitor in parallel, and a second matching branch formed by connecting a second inductor and a second capacitor in parallel, where the first matching branch is connected in series with the second matching branch; alternatively, the matching circuit 122 may include a third matching branch formed by connecting the first inductor and the first capacitor in series, and a fourth matching branch formed by connecting the second inductor and the second capacitor in series, where the third matching branch is connected in parallel with the fourth matching branch.

The matching circuit 122 is configured to achieve impedance matching of the first resonant mode and/or the second resonant mode. As can be appreciated, the matching circuit 122 is configured to achieve impedance matching of the first resonant mode; alternatively, the matching circuit 122 is configured to implement impedance matching of the second resonant mode; alternatively, the matching circuit 122 is configured to perform impedance matching in the first resonant mode and impedance matching in the second resonant mode. Impedance matching refers to an operation state in which the load impedance and the internal impedance of the signal source 10 are matched with each other to obtain the maximum power output. When the matching circuit 122 is used to achieve impedance matching of the first resonant mode, it can be understood that when the matching circuit 122 is in the first resonant mode, the internal resistance of the signal source 10 is equal to the load impedance, i.e. the impedance of the antenna radiator 120 between the first ground terminal B and the first free terminal a, and the phases are the same. When the matching circuit 122 is used to implement impedance matching of the second resonant mode, it can be understood that when the matching circuit 122 is used to implement impedance matching of the second resonant mode, the internal resistance of the signal source 10 is equal to the load impedance and the phase is the same, and at this time, the load impedance is the sum of the impedance of the antenna radiator 120 between the first ground terminal B and the first connection point D and the impedance of the first tuning circuit 121.

By having the antenna unit 12 further comprise a matching circuit 122 electrically connected between the feed point C and the signal source 10, the matching circuit 122 is configured to achieve impedance matching of the first resonant mode and/or the second resonant mode, the reflected signal of the antenna radiator 120 may be reduced, and the efficiency of the antenna assembly 100 may be improved.

As shown in fig. 8, the length of the antenna radiator 120 between the first connection point D and the first free end a is less than or equal to 1/4 of the length of the antenna radiator 120 between the first free end a and the first ground end B. It will be appreciated that the first connection point D is located on a side of the midpoint of the antenna radiator 120 facing away from the first ground terminal B and relatively close to the first free end a. In this embodiment, the first free end a is one end of the antenna radiator 120, the first ground end B is the other end of the antenna radiator 120, and the length of the antenna radiator 120 between the first free end a and the first ground end B can be understood as the overall length of the antenna radiator 120. The length of the antenna radiator 120 between the first connection point D and the first free end a can be referred to as L1 in fig. 8. The length of the antenna radiator 120 between the first free end a and the first ground end B can be referred to L2 shown in fig. 8. In one possible embodiment, the first target frequency band includes LTE B3 and LTE B1, the length of the antenna radiator 120 between the first free end a and the first ground end B may be 35mm to 55mm, and the length of the antenna radiator 120 between the first connection point D and the first free end a may be less than or equal to 10mm.

By making the length of the antenna radiator 120 between the first connection point D and the first free end a less than or equal to 1/4 of the length of the antenna radiator 120 between the first free end a and the first ground end B, the excitation of the second resonance mode is facilitated on the antenna radiator 120 between the first ground end B and the first connection point D, and the length of the antenna radiator 120 itself can be used more, reducing the design difficulty of the first tuning circuit 121.

As shown in fig. 8, the length of the antenna radiator 120 between the feeding point C and the first ground terminal B is less than or equal to 1/4 of the length of the antenna radiator 120 between the first free end a and the first ground terminal B. It will be appreciated that the feed point C is located on the side of the midpoint of the antenna radiator 120 facing away from the first free end a and relatively close to the first ground end B. The length of the antenna radiator 120 between the feeding point C and the first ground terminal B may be referred to L3 shown in fig. 8. In one possible embodiment, the first target frequency band includes LTE B3 and LTE B1, and the length of the antenna radiator 120 between the feeding point C and the first ground B may be less than or equal to 15mm.

By making the length of the antenna radiator 120 between the feeding point C and the first ground terminal B smaller than or equal to 1/4 of the length of the antenna radiator 120 between the first free terminal a and the first ground terminal B, excitation of the first resonance mode is facilitated on the antenna radiator 120 between the first ground terminal B and the first free terminal a, and other modes excited on the antenna radiator 120 can be reduced.

The first resonant mode forms a first current strong point at the first ground terminal B, forms a first current weak point at the first free terminal a, and gradually reduces the current intensity between the first ground terminal B and the first free terminal a. The second resonance mode forms a second current strong point at the first grounding end B, forms a third current strong point at the first connecting point D, and gradually reduces and then gradually increases the current intensity between the first grounding end B and the first connecting point D.

It can be understood that the antenna radiator 120 has a first current strong point, a second current strong point and a third current strong point, and the first current strong point and the second current strong point are both formed at the first ground terminal B, but since the first current strong point and the second current strong point are the current strong points of the first resonant mode and the second resonant mode respectively, and the second resonant mode not only has the second current strong point but also has the third current strong point formed at the first connection point D, the current strong points of the antenna radiator 120 can be dispersed with respect to the antenna radiator 120 generating only one resonant mode, so that the SAR value can be further reduced under the premise of ensuring the communication performance.

In one possible embodiment, as shown in fig. 9, the second resonant mode forms a second current weakness at the target point E. It can be appreciated that the second resonant mode forms a second current strong point at the first ground terminal B, a third current strong point at the first connection point D, a second current weak point at the target point E, a current intensity gradually decreasing from the first connection point D to the target point E, and a current intensity gradually increasing from the target point E to the first ground terminal B. The target point E is located between the first connection point D and the feeding point C. Optionally, the target point E is relatively close to the first connection point D and relatively far from the feeding point C; alternatively, the target point E is relatively close to the feeding point C and relatively far from the first connecting point D; alternatively, the target point E is located at the midpoint between the first connection point D and the feeding point C.

Because the feeding point C is close to the first grounding end B and is favorable for exciting the first resonant mode, and the first connecting point D is close to the first free end a and is favorable for exciting the second resonant mode, the second resonant mode forms a second current weak point at the target point E, and the target point E is located between the first connecting point D and the feeding point C, so that the antenna radiator 120 between the feeding point C and the first grounding end B in the first resonant mode has stronger resonant current, and the antenna radiator 120 between the feeding point C and the first grounding end B in the second resonant mode has stronger resonant current, thereby ensuring the resonant current intensity of the first resonant mode and the second resonant mode, and ensuring the antenna assembly 100 to have better communication performance supporting the first target frequency band.

As shown in fig. 10, the feeding point C is moved to be close to the first ground end B of the antenna radiator 120, and the inductor is only connected to the first free end a close to the antenna radiator 120 to reduce the SAR value, without increasing the area and length of the antenna radiator 120. As shown in fig. 10, after the end of the antenna radiator 120 is connected to the inductor, the boundary condition of the antenna is changed, so that the antenna assembly 100 includes two resonant mode components, namely, a 1/4 wavelength mode of the inverted-F antenna and a half-wavelength mode of the loop antenna introduced by the inductor. According to the radiation principles of the inverted-F antenna and the loop antenna, the 1/4 wavelength mode of the inverted-F antenna generates a strong current point Imax1 at the first grounding end B, the half-wavelength mode of the loop antenna simultaneously generates strong current points Imax2 and Imax3 at the first grounding end B and the first connecting point D, so that the strong current point Imax on the antenna radiator 120 is equal to the sum of Imax1 and Imax2, the strong point splitting effect on the antenna radiator 120 is achieved, and the requirement of reducing the SAR value of the LTE B3/B1 frequency band is met.

Referring to fig. 11 and fig. 12, fig. 11 (a) is a schematic view of a part of the structure of an electronic device 1000 according to an embodiment of the present application; fig. 11 (b) is a schematic diagram of the electronic device 1000 of fig. (a) with the antenna assembly 100 removed from the first tuning circuit 121; fig. 11 (c) is a schematic structural diagram of the electronic device 1000 of fig. (a), in which the antenna assembly 100 has the first tuning circuit 121 removed and the length of the antenna radiator 120 increased. Curve (d) in fig. 12 is a return loss curve of the antenna assembly 100 in the electronic device 1000 in fig. 11 (a); curve (e) in fig. 12 is the return loss curve corresponding to the electronic device of (b) in fig. 11; curve (f) in fig. 12 is a return loss curve corresponding to the electronic device in fig. 11 (c). From the curves (d), e and f) in fig. 12, it can be seen that all three electronic devices can support LTE B3/B1 bands. As shown in table 1, table 1 shows SAR value measured data of the antenna element shown in fig. 11 (a), fig. b, and fig. c). As can be seen from table 1, in the electronic device 1000 of the scheme (a), the antenna module 100 and the electronic device of the scheme (c) can obtain a SAR value reduction of about 30% compared with the electronic device of the scheme (b), and the effect is remarkable. Meanwhile, compared with the antenna assembly 100 in the electronic device 1000 in the diagram (a), the antenna assembly 100 in the diagram (c) in the embodiment of the application does not need to increase the area and the length of the antenna radiator 120, occupies a small space, and is convenient for the layout of the antenna assembly 100 in the electronic device 1000.

Table 1:

referring to fig. 11 and 13, fig. 13 (g) is a current distribution simulation diagram corresponding to the antenna assembly 100 in the electronic device 1000 of fig. 11 (a); fig. 13 (h) is a current distribution simulation diagram corresponding to the antenna assembly in the electronic device in fig. 11 (B), and it can be seen from fig. 13 (g) and (h) that the antenna assembly 100 in the (a) diagram provided in the embodiment of the present application has two obvious hot spots, the two hot spots are respectively located at the first connection point D and the first ground terminal B of the antenna radiator 120, and only one hot spot is located at the return ground terminal, so that the technical effects of the dual resonance mode can be demonstrated.

Further, as shown in fig. 14, the antenna assembly 100 further includes a parasitic element 13. The parasitic element 13 includes a parasitic stub 130 and a second tuning circuit 131. The parasitic dendrites 130 are disposed on the border 300. Alternatively, the parasitic dendrite 130 may be provided on an inner surface of the bezel 300, or the parasitic dendrite 130 may be integrated on the bezel 300, or the parasitic dendrite 130 may be provided on an outer surface of the bezel 300. In other words, the parasitic dendrite 130 may be an internal parasitic dendrite, or the parasitic dendrite 130 may be a metal middle frame parasitic dendrite, or the parasitic dendrite 130 may be an external parasitic dendrite. The parasitic dendrite 130 is exemplified by a metal center parasitic dendrite in the following embodiments, unless explicitly stated. The material of the parasitic branch 130 may include at least one conductive material such as metal, alloy, carbon fiber, etc. The second tuning circuit 131 may include a capacitance and/or an inductance, etc. The number of capacitors and the number of inductors included in the second tuning circuit 131 are not particularly limited in this application. When the second tuning circuit 131 includes a plurality of capacitors, the plurality of capacitors may be connected in series or in parallel. When the second tuning circuit 131 includes a plurality of inductors, the plurality of inductors may be connected in series or in parallel. When the second tuning circuit 131 includes one or more capacitors and one or more inductors, the inductors and the capacitors may be connected in series or in parallel. The second tuning circuit 131 may be matched inductively or capacitively, respectively, depending on the frequency bands supported by the parasitic stub 130. The second tuning circuit 131 is disposed on the circuit board 200.

The parasitic branch 130 includes a second free end F, a second ground end G, and a second connection point H disposed between the second free end F and the second ground end G. The second free end F may be understood as the end or port of the parasitic stub 130 coupled to the antenna radiator 120. The second ground G may be understood as the parasitic stub 130 electrically connected to an end or port of the reference ground 11. The second connection point H may be understood as a port at which the parasitic branch 130 is electrically connected to the second tuning circuit 131.

In one possible embodiment, the parasitic branch 130 is linear, one end of the parasitic branch 130 forms the second free end F, and the other end of the parasitic branch 130 forms the second ground end G. The second connection point H is disposed between the second free end F and the second ground end G, and is spaced apart from the second free end F and the second ground end G. In the present embodiment, the parasitic branch 130 may be disposed in one of the first sub-frame 30, the second sub-frame 31, the third sub-frame 32, and the fourth sub-frame 33.

Of course, in other possible embodiments, the parasitic branch 130 may include a first parasitic segment and a second parasitic segment that are connected in a bent manner, where an end of the first parasitic segment away from the second parasitic segment forms the second free end F, and an end of the second parasitic segment away from the first parasitic segment forms the second ground end G. The second connection point H may be provided at the first parasitic segment or the second parasitic segment. In the present embodiment, the parasitic branch 130 may be disposed in two adjacent ones of the first sub-frame 30, the second sub-frame 31, the third sub-frame 32, and the fourth sub-frame 33. For example: one of the first parasitic segment and the second parasitic segment is arranged on the first sub-frame 30, and the other is arranged on the second sub-frame 31 or the fourth sub-frame 33; alternatively, one of the first parasitic segment and the second parasitic segment is disposed on the third sub-frame 32, and the other is disposed on the second sub-frame 31 or the fourth sub-frame 33.

The second free end F forms a coupling gap with the first free end a. In other words, the parasitic stub 130 and the antenna radiator 120 are coupled through a coupling gap, that is, the parasitic stub 130 and the antenna radiator 120 may achieve transmission of radiation energy through the coupling gap. Wherein the size of the coupling gap may be 0.5mm to 2mm.

The second ground terminal G is electrically connected to the reference ground 11. The second ground terminal G may be directly or indirectly electrically connected to the reference ground 11. For example: the second ground terminal G and the reference ground 11 may be directly welded, or electrically connected through electrical connectors such as conductive wires, conductive elastic sheets, conductive adhesives, etc.

The second connection point H is electrically connected to the reference ground 11 through the second tuning circuit 131. In other words, the second tuning circuit 131 is electrically connected between the second connection point H and the reference ground 11. The second tuning circuit 131 may be directly electrically connected to the second connection point H or may be indirectly electrically connected to the second connection point H. For example: the second tuning circuit 131 and the second connection point H may be directly welded, or electrically connected through an electrical connection member such as a conductive wire, a conductive spring, or a conductive adhesive. The second tuning circuit 131 may be directly electrically connected to the reference ground 11 or indirectly electrically connected to the reference ground. For example: the second tuning circuit 131 and the reference ground 11 may be directly soldered, or electrically connected through electrical connectors such as conductive wires, conductive spring plates, conductive adhesives, etc.

As shown in fig. 15, the parasitic branch 130 between the second ground terminal G and the second free terminal F is configured to generate a third resonance mode supporting the second target frequency band under the excitation of the signal source 10, where the third resonance mode is a 1/4 wavelength mode. It is understood that the third resonant current corresponding to the third resonant mode is distributed between the second ground terminal G and the second free terminal F of the parasitic branch 130. The third resonant current corresponding to the third resonant mode may be referred to as I3 shown in fig. 15. It should be noted that, since the third resonant current is an alternating current, the direction of the third resonant current changes periodically, and thus the direction I3 in the drawing is only one possible flow direction of the third resonant current. The parasitic stub 130 may receive and/or transmit electromagnetic wave signals of the second target frequency band in the third resonant mode.

The second target frequency band is not specifically limited in this application. For example: the second target frequency band may be located in a low frequency (less than or equal to 1 GHz) band; alternatively, the second target frequency band may be located in a medium-high frequency (greater than 1GHz and less than or equal to 3 GHz) frequency band, or the second target frequency band may be located in an ultra-high frequency (greater than 3 GHz) frequency band. The second target frequency band may be different from the first target frequency band. In one possible embodiment, the center frequency of the second target frequency band may be higher than the center frequency of the first target frequency band.

In one possible embodiment, when the parasitic branch 130 between the second ground terminal G and the second free terminal F generates a strong and weak resonant current under the excitation of the signal source 10, and the resonant current generated at the second ground terminal G is relatively strong, and the resonant current generated at the second free terminal F is relatively weak, the parasitic branch 130 between the second ground terminal G and the second free terminal F may be considered to generate a third resonant mode under the excitation of the signal source 10, the third resonant mode being a 1/4 wavelength mode. In other words, the third resonant mode forms a strong current point at the second ground terminal G, a weak current point at the second free terminal F, and the current intensity between the second ground terminal G and the second free terminal F gradually decreases.

In another possible embodiment, when the electrical length of the parasitic stub 130 between the second ground terminal G and the second free terminal F is equal to or close to 1/4 wavelength of the second target frequency band, the parasitic stub 130 between the second ground terminal G and the second free terminal F may be considered to generate a third resonant mode under excitation of the signal source 10, the third resonant mode being a 1/4 wavelength mode. Wherein the electrical length of the parasitic branch 130 between the second ground terminal G and the second free terminal F is equal to k2 PL 3. k2 is the ratio of the transmission time of the electric or electromagnetic wave signal in the second target frequency band in the medium to the transmission time in the free space; PL3 is the physical length of the parasitic stub 130 between the second ground terminal G and the second free terminal F.

As shown in fig. 16, the parasitic branch 130 and the second tuning circuit 131 between the second ground terminal G and the second connection point H are configured to generate a fourth resonance mode supporting the second target frequency band under the excitation of the signal source 10, where the fourth resonance mode is a 1/2 wavelength mode. It can be understood that the fourth resonant current corresponding to the fourth resonant mode is distributed between the second ground terminal G of the parasitic branch 130 and the second connection point H, and the second tuning circuit 131. The fourth resonant current corresponding to the fourth resonant mode may be referred to as I4 in fig. 16. It should be noted that, since the second parasitic current is an alternating current, the direction of the fourth resonant current changes periodically, and thus the direction I4 in the drawing is only one possible flow direction of the fourth resonant current. The parasitic stub 130 may receive and/or transmit electromagnetic wave signals of the second target frequency band in the fourth resonant mode.

In one possible implementation, when the parasitic branch 130 between the second ground G and the second connection point H generates a resonant current that is weakened by strength and then strengthened by strength under the excitation of the signal source 10, and the resonant current generated at the second ground G and the second connection point H is relatively strong and has a current weakness between the second ground G and the second connection point H, the parasitic branch 130 between the second ground G and the second connection point H and the second tuning circuit 131 may be considered to generate a fourth resonant mode under the excitation of the signal source 10, and the fourth resonant mode is a 1/2 wavelength mode. In other words, the fourth resonant mode forms a strong current point at the second ground terminal G, forms a strong current point at the second connection point H, and gradually decreases and then gradually increases the current intensity between the second ground terminal G and the second connection point H.

In another possible embodiment, when the sum of the electrical length of the parasitic branch 130 between the second ground G and the second connection point H and the equivalent electrical length of the second tuning circuit 131 is equal to or close to 1/2 wavelength of the second target frequency band, the parasitic branch 130 between the second ground G and the second connection point H and the second tuning circuit 131 may be considered to generate a fourth resonance mode under excitation of the signal source 10, the fourth resonance mode being a 1/2 wavelength mode. Wherein the electrical length of the parasitic branch 130 between the second ground G and the second connection point H is equal to k2 PL 4. k2 is the ratio of the transmission time of the electric or electromagnetic wave signal in the second target frequency band in the medium to the transmission time in the free space; PL4 is the physical length of the parasitic stub 130 between the second ground G and the second connection point H.

In this embodiment, the parasitic branch 130 has a plurality of current strong points formed by the third resonant mode and the fourth resonant mode, where the third resonant mode is a 1/4 wavelength mode and the fourth resonant mode is a 1/2 wavelength mode, so that the plurality of current strong points are distributed at different positions of the parasitic branch 130, thereby achieving the effect of current strong point splitting on the parasitic branch 130 and reducing the SAR value. In addition, the third resonance mode and the fourth resonance mode support the second target frequency band at the same time, so that the communication performance of the second target frequency band is not reduced, namely the SAR value is further reduced on the premise of ensuring the communication performance.

As shown in fig. 17, the second tuning circuit 131 is inductive. Optionally, the second tuning circuit 131 includes an inductor; alternatively, the second tuning circuit 131 includes a plurality of inductors connected in series; alternatively still, the second tuning circuit 131 comprises at least one inductance and at least one capacitance, wherein the effect of the inductance is greater than the effect of the capacitance. In one possible implementation, the second tuning circuit 131 includes an inductor. The second tuning circuit 131 is connected in series between the reference ground 11 and the second connection point H of the parasitic branch 130.

The second tuning circuit 131 is inductive, and can correspondingly prolong the electrical length of the parasitic branch 130, which is more beneficial for the parasitic branch 130 between the second ground terminal G and the second connection point H, and the second tuning circuit 131 to generate a fourth resonance mode supporting the low frequency band or the middle-high frequency band under the excitation of the signal source 10, so as to facilitate solving the technical problem that the communication performance and the SAR value cannot be considered in the frequency band needing to consider the power backoff in the low frequency band or the middle-high frequency band.

As shown in fig. 18, the length of the parasitic branch 130 between the second connection point H and the second free end F is less than or equal to 1/4 of the length of the parasitic branch 130 between the second free end F and the second ground end G. It will be appreciated that the second connection point H is located on a side of the midpoint of the parasitic branch 130 facing away from the second ground terminal G and relatively close to the second free terminal F. In this embodiment, the second free end F is one end of the parasitic branch 130, the second ground end G is the other end of the parasitic branch 130, and the length of the parasitic branch 130 between the second free end F and the second ground end G can be understood as the overall length of the parasitic branch 130. The length of the parasitic stub 130 between the second connection point H and the second free end F can be referred to as L4 in fig. 18. The length of the parasitic stub 130 between the second free end F and the second ground end G can be referred to L5 in fig. 18.

In one possible embodiment, the center frequency of the second target frequency band may be higher than the center frequency of the first target frequency band, the length of the parasitic stub 130 between the second free end F and the second ground end G may be smaller than the length of the antenna radiator 120 between the first free end a and the first ground end B, and the length of the parasitic stub 130 between the second connection point H and the second free end F may be smaller than the length of the antenna radiator 120 between the first connection point D and the first free end a.

The length of the parasitic branch 130 between the second free end F and the second ground end G is smaller than or equal to 1/4 of the length of the parasitic branch 130 between the second free end F and the second connection point H, so that excitation of the fourth resonance mode is facilitated on the parasitic branch 130 between the second ground end G and the second connection point H, the length of the parasitic branch 130 can be utilized more, and the design difficulty of the second tuning circuit 131 is reduced.

The features mentioned in the description, in the claims and in the drawings may be combined with one another at will as far as they are relevant within the scope of the present application. The advantages and features described for the antenna apply in a corresponding manner to the electronic device 1000.

While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the present application, and that variations, modifications, alternatives and alterations of the above embodiments may be made by those skilled in the art within the scope of the present application, which are also to be regarded as being within the scope of the protection of the present application.

Claims

1. An antenna assembly, comprising:

a signal source;

2. The antenna assembly of claim 1, wherein the first tuning circuit is inductive; the antenna unit further comprises a matching circuit electrically connected between the feed point and the signal source, the matching circuit being adapted to achieve impedance matching of the first resonance mode and/or to achieve impedance matching of the second resonance mode.

3. The antenna assembly of claim 1, wherein a length of the antenna radiator between the first connection point and the first free end is less than or equal to 1/4 a length of the antenna radiator between the first free end and the first ground end.

4. The antenna assembly of claim 1, wherein a length of the antenna radiator between the feed point and the first ground is less than or equal to 1/4 a length of the antenna radiator between the first free end and the first ground.

5. The antenna assembly of any one of claims 1-4, wherein the first resonant mode forms a first current strong point at the first ground terminal, a first current weak point at the first free terminal, and a current strength between the first ground terminal and the first free terminal gradually decreases; the second resonance mode forms a second current strong point at the first grounding end, forms a third current strong point at the first connecting point, and gradually reduces and then gradually increases the current intensity between the first grounding end and the first connecting point.

6. The antenna assembly of claim 5, wherein the second resonant mode forms a second current weakness at a target point, the target point being located between the first connection point and the feed point.

7. The antenna assembly of any one of claims 1 to 4, further comprising a parasitic element, the parasitic element comprising a parasitic stub and a second tuning circuit, the parasitic stub comprising a second free end, a second ground end, and a second connection point disposed between the second free end and the second ground end, the second free end and the first free end forming a coupling gap therebetween, the second ground end being electrically connected to the reference ground, the second connection point being electrically connected to the reference ground through the second tuning circuit, the parasitic stub between the second ground end and the second free end producing a third resonant mode supporting a second target frequency band under excitation of the signal source, the third resonant mode being a 1/4 wavelength mode, the parasitic stub between the second ground end and the second connection point, the second tuning circuit producing a fourth resonant mode supporting the second target frequency band under excitation of the signal source, the fourth resonant mode being a 1/2 wavelength mode.

8. The antenna assembly of claim 7, wherein the second tuning circuit is inductive.

9. The antenna assembly of claim 7, wherein a length of the parasitic stub between the second connection point and the second free end is less than or equal to 1/4 a length of the parasitic stub between the second free end and the second ground end.

10. An electronic device, comprising a frame, a circuit board, and the antenna assembly of any one of claims 1 to 9, wherein the frame encloses a housing space, the circuit board is disposed in the housing space, the signal source, the reference ground, and the first tuning circuit are disposed on the circuit board, and the antenna radiator is disposed on the frame.