CN117393994A

CN117393994A - Antenna system and terminal device

Info

Publication number: CN117393994A
Application number: CN202211285478.4A
Authority: CN
Inventors: 魏鲲鹏; 李余占; 白陶龙
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2022-07-04
Filing date: 2022-07-04
Publication date: 2024-01-12
Also published as: CN114883791B; CN114883791A

Abstract

The application relates to the technical field of antennas, and provides an antenna system and terminal equipment, wherein the antenna system comprises: the first radiation branch, the second radiation branch and the third radiation branch are provided with a first gap between the first radiation branch and the second radiation branch, and a second gap between the second radiation branch and the third radiation branch; a first feeding point and a first return point are arranged on the first radiation branch, a second return point and a third return point are arranged on the second radiation branch, and a second feeding point and a fourth return point are arranged on the third radiation branch; the antenna system further includes: the first radiation branch is connected with the second radiation branch through the first capacitor, and the second radiation branch is connected with the third radiation branch through the second capacitor. The antenna system can improve the antenna efficiency, ensure the working bandwidth and reduce the SAR value.

Description

Antenna system and terminal device

Technical Field

The application relates to the technical field of antennas, in particular to an antenna system and terminal equipment.

Background

With the rapid development of terminal devices and the increasingly promoted use demands of people, the terminal devices are increasingly widely applied to the production and life of people, and the requirements of users on the communication quality and safety of the terminal devices are also higher.

The communication quality of the terminal device depends to a large extent on the performance of the terminal antenna provided on the terminal device. With the popularity of the fifth Generation mobile communication technology (5 th-Generation, 5G) and the higher screen ratio, the space left for the terminal antenna on the terminal device is smaller and smaller, which results in more challenges for the design process of the terminal antenna.

Liquid crystal display (liquid crystal display, LCD) screens are used in some terminal devices, and the iron frame of the LCD screen needs to be grounded through a spring plate, so that the grounding mode can affect the performance of the antenna, and the efficiency of the antenna is reduced. In addition, when a Chip On Flex (COF) technology is used, a flexible substrate circuit is arched, so that the antenna clearance is directly reduced, the parameters of the antenna are deteriorated, and particularly, the efficiency of the antenna in an intermediate frequency Band such as Band1 or Band3 is reduced, and the communication quality is affected.

Disclosure of Invention

The application provides an antenna system and terminal equipment, which can improve the antenna efficiency of the antenna system, ensure the working bandwidth and reduce the value of the specific absorption rate (specific absorption rate, SAR) of electromagnetic radiation.

In a first aspect, an antenna system is provided, comprising: the first radiation branch, the second radiation branch and the third radiation branch are provided with a first gap between the first radiation branch and the second radiation branch, and a second gap between the second radiation branch and the third radiation branch; a first feeding point and a first return point are arranged on the first radiation branch, a second return point and a third return point are arranged on the second radiation branch, and a second feeding point and a fourth return point are arranged on the third radiation branch; the antenna system further includes: the first radiation branch is connected with the second radiation branch through the first capacitor, and the second radiation branch is connected with the third radiation branch through the second capacitor.

In the antenna system, the first radiating branch is connected with the second radiating branch through the first capacitor, and the second radiating branch is connected with the third radiating branch through the second capacitor, so that current on the main radiator can be led to other parasitic radiators, uniform transverse current is formed on the main radiator and the parasitic radiator, the radiating volume of the effective radiator is enlarged, namely the radiating caliber of the antenna is enlarged, and the efficiency of the whole antenna system is improved.

The second radiation branch is respectively provided with a second return point and a third return point, so that the second radiation branch can form a current loop under the excitation of signals, and therefore, the current can be uniformly distributed on the second radiation branch to form a resonant mode with half wavelength, and compared with a resonant mode with quarter wavelength of only one return point, the efficiency of the antenna system can be improved.

Meanwhile, the antenna system can lead a large amount of current on the main radiator to other parasitic radiators through the arrangement of the first capacitor and the second capacitor, so that SAR hot spots are dispersed. After the SAR hot spot is dispersed, the SAR value can be correspondingly reduced, and the position of the SAR hot spot can not be directly held when a user holds the terminal equipment, so that the maximum transmitting power of the terminal equipment is not required to be reduced by a larger extent in the scene of the head-hand model, the SAR value can meet the regulation requirement only by reducing or not reducing by a smaller extent, the large reduction of TRP is avoided, the uniformity of the reduction of the maximum transmitting power in the scene of the head-hand model at the left side and the right side of the terminal equipment is improved, and the excessive fluctuation of the TRP in different scenes is further avoided.

In some possible implementations, the first feed point is for feeding a high frequency signal and/or an intermediate frequency signal, and the second feed point is for feeding a low frequency signal.

When the first feed point feeds in the high-frequency signal, a current loop can be formed on the second radiation branch, and the current excited by the high-frequency signal can be uniformly distributed on the second radiation branch, so that the efficiency of the antenna system at high frequency is improved. When the first feed point feeds in an intermediate frequency signal, through the arrangement of the first capacitor and the second capacitor, the current on the first radiation branch serving as a main radiator can be led to the second radiation branch and the third radiation branch serving as parasitic radiators, and uniform transverse current is formed on the three radiation branches, so that the radiation volume of an effective radiator is enlarged, namely the radiation caliber of an antenna is enlarged, and the efficiency of the antenna system at the intermediate frequency is improved. When the second feeding point feeds in a low-frequency signal, the current on the third radiation branch serving as the main radiator can be led to the second radiation branch and the first radiation branch serving as the parasitic radiator through the arrangement of the first capacitor and the second capacitor, so that the efficiency of the antenna system at low frequency is improved.

In some possible implementations, the first feeding point is located at an end of the first radiating branch near the second radiating branch, the second return point is located at an end of the second radiating branch near the first radiating branch, and the second return point and the first feeding point are connected through the first capacitor.

In some possible implementations, the first return point is located at an end of the first radiating branch that is remote from the second radiating branch; the second feed point is located the one end that the third radiation branch is close to the second radiation branch, and the fourth place of returning is located the one end that the third radiation branch kept away from the second radiation branch, and the third place of returning is located the one end that the second radiation branch is close to the third radiation branch, and second feed point and third place of returning pass through the second electric capacity and connect.

The first radiation branch is connected with the second radiation branch through the first capacitor, and the second radiation branch is connected with the third radiation branch through the second capacitor, so that current on the main radiator can be led to other parasitic radiators, uniform transverse current is formed on the main radiator and the parasitic radiator, the radiation volume of the effective radiator is enlarged, namely the radiation caliber of the antenna is enlarged, and the efficiency of the whole antenna system is improved.

The second radiation branch is respectively provided with a second return point and a third return point, so that the second radiation branch can form a current loop under the excitation of a high-frequency signal or an intermediate-frequency signal, and therefore, current can be uniformly distributed on the second radiation branch to form a resonant mode with half wavelength, and compared with a resonant mode with a quarter wavelength with only one return point, the efficiency of an antenna system can be improved.

In some possible implementations, the method further includes: a first switch and a second switch; the first feed point and the second return point are grounded through a first switch; the second feeding point and the third return point are grounded through a second switch.

When the antenna system is excited by signals with different frequencies, the first switch and the second switch can be switched to corresponding channels to select a matching circuit which enables the current frequency to reach a tuning state, so that the antenna system can reach a resonance mode under the excitation of the signals with different frequencies, the antenna performance of the antenna system at a plurality of frequencies can meet radiation requirements, and the antenna system has broadband characteristics.

In some possible implementations, the first return point is located at an end of the first radiating branch that is remote from the second radiating branch; the second feed point is located the one end that the third radiation branch kept away from the second radiation branch, and the fourth place of returning is located the one end that the third radiation branch is close to the second radiation branch, and the third place of returning is located the one end that the second radiation branch is close to the third radiation branch, and the third place of returning is connected through the second electric capacity with the fourth place of returning.

When the second feeding point is located at one end of the third radiating branch and is far away from the second radiating branch, and the fourth return point is located at one end of the third radiating branch and is close to the second radiating branch, the third radiating branch is singly an inverted-F-shaped antenna (IFA), the whole third radiating branch is a main radiator, the second feeding point is located at one end of the third radiating branch and is close to the second radiating branch, and the fourth return point is located at one end of the third radiating branch and is far away from the second radiating branch, so that the main radiator is long, the effective radiating volume is large, and the antenna efficiency is improved.

In some possible implementations, the antenna system further includes: a first switch and a second switch; the first feed point and the second return point are grounded through a first switch; the third return point and the fourth return point are grounded through a second switch.

In some possible implementations, the form of the matching circuit connected to each path of the first switch is different, and the form of the matching circuit connected to each path of the second switch is different. The different matching circuit forms on each passage of the first switch and the second switch can respectively meet the resonance states of signals with different frequencies, so that the antenna system has broadband characteristics.

In some possible implementations, a fifth return point is also provided on the first radiating branch, the fifth return point being located between the first feed point and the first return point. By setting the fifth pass point, the current distribution on the first radiation branch can be more uniform, and the SAR value is further reduced.

In some possible implementations, the antenna system further includes: a third switch; the fifth pass point is grounded through the third switch.

When the antenna system is excited by signals with different frequencies, the third switch can be switched to the corresponding channel to select the matching circuit which enables the current frequency to reach the tuning state, so that the antenna system can reach the resonance mode under the excitation of the signals with different frequencies, the antenna performance of the antenna system at a plurality of frequencies can meet the radiation requirement, the broadband characteristic is achieved, and the SAR value in the broadband range is reduced.

In some possible implementations, the form of the matching circuit to which each path of the third switch is connected is different. The different forms of the matching circuits on the paths of the third switch can respectively meet the resonance states of signals with different frequencies, so that the antenna system has broadband characteristics.

In some possible implementations, the distance of the first feed point from the first slot is greater than or equal to a first distance threshold.

In some possible implementations, the antenna system further includes a third capacitor, and the first feed point is connected to the first feed source through the third capacitor in series.

If the first feeding point is disposed at a position close to the first slot, a bonding pad (so-called feeding tongue) corresponding to the first feeding point and a spring piece contacted with the bonding pad transfer a strong point of an electric field to a PCB where the bonding pad is located (i.e. a non-clearance area of an antenna) through the first slot, and at this time, the performance of the antenna is reduced due to the existence of the PCB. In this embodiment, the first feeding point is set to be greater than the first distance threshold with the first gap interval, and the first feeding point is connected with the first feed source through the third capacitor in series, so that the first radiating branch forms a left-hand antenna, and strong points of an electric field distributed on the first radiating branch are prevented from being transferred to a non-headroom region of the antenna through the first gap by the spring piece connected with the feeding tongue and the first feeding point, the influence of the existence of the PCB on the antenna performance is avoided, and the antenna performance can be ensured.

In some possible implementations, the antenna system is applied to a terminal device, where the terminal device includes a universal serial bus USB connector, and a distance between a first side of the second radiating branch and the USB connector is less than or equal to a second distance threshold, and the first side of the second radiating branch is a side where the second return point and the third return point are located.

By setting the distance between the first side of the second radiation branch and the USB connector of the first radiation branch and the USB connector to be smaller than or equal to the second distance threshold value, signal coupling can be realized between the first side of the second radiation branch and the USB connector, and the USB connector is used as a parasitic radiation branch of the second radiation branch. The existing USB connector on the terminal equipment is used as a parasitic radiation branch, so that the volume of an effective radiator can be increased by means of the existing structure of the terminal equipment on the premise that the volume of an antenna system is not increased, and the antenna efficiency is improved.

In some possible implementations, the first capacitance is a distributed-parameter capacitance and/or a lumped-parameter capacitance, and the second capacitance is a distributed-parameter capacitance and/or a lumped-parameter capacitance. The first capacitor and the second capacitor can be lumped parameter capacitors, distributed parameter capacitors or a combination of the first capacitor and the second capacitor, and the implementation mode is flexible.

In a second aspect, a terminal device is provided, where the electronic terminal includes any one of the antenna systems according to the first aspect.

Drawings

Fig. 1 is a schematic structural diagram of an example of a terminal device provided in an embodiment of the present application;

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

fig. 3 is an example of an antenna system according to an embodiment of the present application;

FIG. 4 is an equivalent schematic diagram of an example zero-order mode provided in an embodiment of the present application;

fig. 5 is a schematic diagram of another antenna system according to an embodiment of the present disclosure;

fig. 6 is a schematic diagram of another antenna system according to an embodiment of the present disclosure;

fig. 7 is a schematic diagram of another antenna system according to an embodiment of the present disclosure;

fig. 8 is a schematic diagram of another antenna system according to an embodiment of the present disclosure;

FIG. 9 is a graph showing current distribution in different parasitic modes of a second radiation branch according to an embodiment of the present application;

fig. 10 is a graph of parameters of an example antenna system provided in an embodiment of the present application under different matching modes;

FIG. 11 is a graph of parameters of yet another example of an antenna system provided in an embodiment of the present application under different matching patterns;

fig. 12 is a graph comparing parameters of an example antenna system and a common antenna system according to an embodiment of the present application;

Fig. 13 is a graph comparing parameters of an example antenna system and a common antenna system in a B3 band according to an embodiment of the present application;

fig. 14 is a graph comparing parameters of an example antenna system and a common antenna system in a B1 band according to an embodiment of the present application;

fig. 15 is a graph comparing parameters of an example antenna system and a common antenna system in a B7 band according to an embodiment of the present application;

fig. 16 is a graph comparing radiation efficiency of an example antenna system and a common antenna system according to an embodiment of the present application;

fig. 17 is a diagram illustrating SAR values of an example antenna system and a common antenna system according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Wherein, in the description of the embodiments of the present application, "/" means or is meant unless otherwise indicated, for example, a/B may represent a or B; "and/or" herein is merely an association relationship describing an association object, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. In addition, in the description of the embodiments of the present application, "plurality" means two or more than two.

The terms "first," "second," "third," and the like, are used below for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", or a third "may explicitly or implicitly include one or more such feature.

The antenna system provided by the embodiment of the application can be applied to terminal devices such as mobile phones, tablet computers, wearable devices, vehicle-mounted devices, augmented reality (augmented reality, AR)/Virtual Reality (VR) devices, notebook computers, ultra-mobile personal computer (UMPC), netbooks, personal digital assistants (personal digital assistant, PDA) and the like, and the specific types of the terminal devices are not limited.

Referring to fig. 1, a schematic structure diagram of a terminal device 100 according to an embodiment of the present application is provided. As shown in a diagram of fig. 1, the terminal device 100 provided in the embodiment of the present application may sequentially include a screen and a cover plate 101, a metal housing 102, an internal structure 103, and a rear cover 104 from top to bottom along the z-axis.

The screen and the cover 101 may be used to implement a display function of the terminal device 100. The metal housing 102 may serve as a main body frame of the terminal device 100, providing rigid support for the terminal device 100. The internal structure 103 may include a collection of electronic and mechanical components that perform the functions of the terminal device 100. For example, the internal structure 103 may include a shield, screws, ribs, etc. The rear cover 104 may be a back surface of the terminal device 100, and glass, ceramic, plastic, etc. may be used for the rear cover 104 in various implementations.

The antenna system provided in the embodiment of the present application can be applied to the terminal device 100 shown in a diagram a in fig. 1, and is used for supporting the wireless communication function of the terminal device 100. In some embodiments, the antenna system may be disposed on the metal housing 102 of the terminal device 100. In other embodiments, the antenna system to which the antenna scheme relates may be provided on the rear cover 104 of the terminal device 100, or the like.

As an example, taking the metal shell 102 as an example with a metal bezel architecture, fig. 1 b and c illustrate a schematic of the composition of the metal shell 102. The b diagram in fig. 1 is illustrated with the short side of the terminal device where the antenna system is disposed, and the c diagram in fig. 1 is illustrated with the long side of the terminal device where the antenna system is disposed. Of course, the antenna system may also be distributed over the short side of the terminal device and the long side adjacent to the short side. Taking the b-diagram in fig. 1 as an example for illustration, the metal housing 102 may be made of a metal material, such as an aluminum alloy. As shown in b-chart in fig. 1, the metal housing 102 may be provided with a reference ground. The reference ground may be a metallic material having a large area for providing a largely rigid support while providing a zero potential reference for the individual electronic components. In the example shown in b-diagram in fig. 1, a metal bezel may also be provided at the periphery of the reference ground. The metal frame may be a complete closed metal frame, and the metal frame may include a metal strip partially or fully suspended. In other implementations, the metal bezel may also be a metal bezel broken by one or more slits as shown in figure 1 b. For example, in the example shown in b of fig. 1, the metal frame may be provided with a slit 1, a slit 2 and a slit 3 at different positions, respectively. These slits may interrupt the metal rim, thereby obtaining independent metal knots. In some embodiments, some or all of the metal branches may be used as radiating branches of the antenna, so as to implement structural multiplexing in the antenna setting process and reduce the difficulty of antenna setting. When the metal branch is used as a radiation branch of the antenna, the positions of the gaps arranged at one end or two ends of the metal branch can be flexibly selected according to the arrangement of the antenna.

In the example shown in b-diagram in fig. 1, one or more metal pins may also be provided on the metal bezel. In some examples, screw holes may be provided on the metal pins for securing other structural members by screws. In other examples, the metal pin may be coupled to the feed point so that the antenna is fed through the metal pin when the metal pin-connected metal stub is used as a radiating stub of the antenna. In other examples, the metal pins may also be coupled with other electronic components to implement corresponding electrical connection functions. In the embodiment of the present application, in the b and c diagrams in fig. 1, the metal pins may be coupled to the feeding point or may be grounded.

In this example, an illustration of the arrangement of the printed wiring board (printed circuit board, PCB) on the metal housing is also shown. Taking a main board (main board) and a sub board (sub board) sub board design as an example. In other examples, the motherboard and the die may also be connected, such as an L-shaped PCB design. In some embodiments of the present application, a motherboard (e.g., PCB 1) may be used to carry electronic components that perform the functions of terminal device 100. Such as a processor, memory, radio frequency module, etc. A small board, such as PCB2, may also be used to carry electronic components. Such as a universal serial bus (Universal Serial Bus, USB) interface, related circuitry, a sound box (spaak box), etc. As another example, the platelet may also be used to carry radio frequency circuitry or the like corresponding to antennas disposed at the bottom (i.e., the negative y-axis portion of the terminal device).

It should be noted that various radiation branches (a first radiation branch, a second radiation branch, a third radiation branch, a radiation branch 1, a radiation branch 2, a radiation branch 3, and the like) and various radiators mentioned below are the above metal radiation branches.

With the popularity of 5G and the higher screen ratio, the space left for the antenna on the terminal device is smaller and smaller, so that the antenna of the terminal device meets more challenges in the design process. The antenna of the terminal equipment can be used for expanding the bandwidth by arranging a plurality of metal radiation branches to form an antenna system, so that the terminal equipment supports wider frequency bands, the product specification is ensured, and the antenna efficiency is ensured. For example, the antenna system on the terminal equipment can be provided with three metal radiation branches, and the communication frequency band in the range of 700MHz to 2.69GHz can be covered by debugging the matching circuit. A common antenna system of a terminal device may refer to the scheme shown in fig. 2, including: three radiators of radiation branch 1, radiation branch 2 and radiation branch 3. Signals of different frequency bands can be fed through the feed source 1 or the feed source 2. When the feed source 1 is adopted for feeding, the radiation branch 1 can be used as a main radiator, the radiation branch 2 and the radiation branch 3 can be used as parasitic radiators, and signals in a frequency band, such as intermediate frequency signals or high frequency signals, can be commonly transmitted and received. When the feed source 2 is adopted for feeding, the radiation branch 3 can be used as a main radiator, the radiation branch 2 and the radiation branch 1 can be used as parasitic radiators, and signals in another frequency range, such as low-frequency signals, can be received and transmitted together. In general, a series capacitor C1 may be added between the feed 1 and the feed point of the antenna, and a series capacitor C2 may be added between the feed 2 and the feed point of the antenna. Wherein C1 and C2 can be used to adjust the matching on the path and block the dc signal. Here, C1 and C2 in series are one illustration of a matching circuit, and are not intended to limit the form of the matching circuit.

However, when the antenna system shown in fig. 2 is used for transmitting the signal fed by the feed source 1, the current distribution on the radiation branch 1 serving as the main radiator is relatively concentrated, so that a SAR hot spot is formed on the radiation branch 1. If a user holds the terminal equipment, the user can easily hold the position of the SAR hot spot on the radiation branch 1, and the SAR value at the moment is easy to exceed the standard in a large range. In order to make the SAR value meet the regulation requirement, larger-amplitude power backoff is needed to be carried out on the frequency band with the SAR exceeding standard, namely, the maximum transmitting power of the frequency band in the SAR scene is greatly reduced to ensure that the SAR value meets the regulation requirement. But this can reduce the total radiated power (total radiated power, TRP) of the antenna system by a large amount, affecting the communication quality.

According to the antenna system, the capacitance is arranged between the adjacent metal radiation branches, and the zero-order modes of the antenna system in different frequency bands (namely, the modes of enabling the antenna system to reach the resonance state) are more easily constructed by adjusting the capacitance value of the capacitance. In the antenna system, the capacitors are arranged between the adjacent metal radiating branches, so that the current intensively distributed on the main radiator can be led to the parasitic radiator, and uniform transverse current is formed on the main radiator and the parasitic radiator. Meanwhile, through arranging the capacitor between the adjacent metal radiation branches, the current intensively distributed by the main radiator can be led to the parasitic radiator, and compared with the traditional mode that a large amount of current is concentrated on the main radiator, the SAR hot spot is dispersed. In general, when the antenna system is disposed at a side of the terminal device, a user holds the terminal device and approaches the head (similar to the head-hand model of the antenna system in SAR test), so that the SAR value meets the requirement of the rule, the maximum transmitting power of the terminal device is controlled to be reduced by a larger extent. After the SAR hot spot is dispersed, the SAR value can be correspondingly reduced, and the handheld position of the user is not the position of the SAR hot spot, so that the maximum transmitting power of the terminal equipment is not required to be reduced by a larger extent in the scene of the head-hand model, and the SAR value can meet the regulation requirement only by reducing or not reducing by a smaller extent, thereby improving the uniformity of the reducing of the maximum transmitting power in the scene of the head-hand model of the terminal equipment, avoiding the overlarge fluctuation of the TRP in different scenes and ensuring the communication quality.

The antenna system provided by the embodiment of the application can be applied to the terminal equipment shown as the a diagram in fig. 1.

For easy understanding, the following embodiments of the present application will take a terminal device having a structure shown in fig. 1 as an example, and specifically describe an antenna system provided in the embodiments of the present application with reference to the accompanying drawings and application scenarios.

Fig. 3 is a schematic structural diagram of an example antenna system according to an embodiment of the present application. The antenna system has the structure shown in fig. 3, and comprises: the first radiation branch 301, the second radiation branch 302 and the third radiation branch 303, wherein a first gap 304 is formed between the first radiation branch 301 and the second radiation branch 302, and a second gap 305 is formed between the second radiation branch 302 and the third radiation branch 303. The first radiation branch 301 is provided with a first feeding point 306 and a first return point 310, the second radiation branch 302 is provided with a second return point 307 and a third return point 308, and the third radiation branch 303 is provided with a second feeding point 309 and a fourth return point 311. The antenna system further includes: a first capacitor C301 and a second capacitor C302, the first radiating branch 301 and the second radiating branch 302 being connected by C301, the second radiating branch 302 and the third radiating branch 303 being connected by C302.

Alternatively, the first feed point 306 may be used to feed the first frequency band signal and the second frequency band signal, and the second feed point may be used to feed the third frequency band signal. For example, the first feeding point 306 is used to feed a high frequency signal and/or an intermediate frequency signal, and the second feeding point is used to feed a low frequency signal.

Alternatively, the third radiating branch may have an L-shaped structure, or may have a "straight" structure, and fig. 3 illustrates an L-shaped structure.

Taking the scenario of transmitting signals by the antenna system as an example, when the first feeding point 306 feeds high-frequency signals or intermediate-frequency signals, the first radiating branch 301 connected to the first feeding point 306 is used as a main radiator, and other radiating branches can be used as parasitic radiators to jointly transmit signals fed to the first feeding point 306. Since C301 is connected between the first radiating branch 301 and the second radiating branch 302, by tuning the capacitance of C301, the capacitance of C301 is matched with the frequency of the transmitted signal, and a zero order mode is easier to construct. The arrangement of C301 is such that a substantial amount of current that would otherwise have concentrated on the first radiating branch 301 flows through C301 to the second radiating branch 302, and the arrangement of C302 may continue to flow current concentrated on the second radiator through C302 to the third radiating branch 303.

When the second feeding point 309 feeds a low frequency signal, the third radiating branch 303 connected to the second feeding point 309 acts as a main radiator, and the other radiating branches may act as parasitic radiators, jointly emitting the low frequency signal fed to the second feeding point 309. Since C302 is connected between the second radiating branch 302 and the third radiating branch 303, it is easier to construct a zero order mode by tuning the capacitance of C302 to match the frequency of the transmitted signal. The arrangement of C302 is such that a substantial amount of the charge that would otherwise have accumulated on the third radiation branch 303 flows through C302 to the second radiation branch 302, and the arrangement of C301 may continue to flow the charge accumulated on the second radiation branch 302 through C301 to the first radiation branch 301.

Optionally, the C301 may be a distributed parameter capacitor, or may be a lumped parameter capacitor, or may be a combination of a distributed parameter capacitor and a lumped parameter capacitor; the C302 may be a distributed parameter capacitor, a lumped parameter capacitor, or a combination of a distributed parameter capacitor and a lumped parameter capacitor. The specific form of C301 and C302 is not limited in the embodiment of the present application as long as the capacitance values of C301 and C302 meet the debug requirement, so that the antenna system reaches the resonance state.

Therefore, the first radiating branch 301 is connected with the second radiating branch 302 through the C301, and the second radiating branch 302 is connected with the third radiating branch 303 through the C302, so that the current on the main radiator can be led to other parasitic radiators, uniform transverse current is formed on the main radiator and the parasitic radiator, the radiating volume of the effective radiator is enlarged, namely the radiating caliber of the antenna is enlarged, and the efficiency of the whole antenna system is improved.

In addition, if only one return point is provided on the second radiating branch 302 according to the conventional antenna scheme, current distribution on the second radiating branch 302 is not uniform and the resonance mode is a quarter wavelength resonance mode. In the embodiment shown in fig. 3, the second radiation branch 302 is provided with a second return point 307 and a third return point 308 at two ends, so that the second radiation branch 302 can form a current loop under the excitation of a high-frequency signal or an intermediate-frequency signal, and therefore, the current can be more uniformly distributed on the second radiation branch 302 to form a resonant mode with a half wavelength, and the efficiency of the antenna system can be improved compared with a resonant mode with a quarter wavelength.

In general, when the radiation branches in the antenna system are arranged on the long side of the terminal device, a user holds the terminal device and approaches to the head (similar to the head-hand model of the antenna system in SAR test), so that the user can easily directly hold the position of the SAR hot spot on the radiation branches on the long side of the terminal device. At this time, the human body is exposed to larger radiation, which is shown by larger SAR value exceeding standard under SAR test scene. In order for the SAR value to meet the requirements of the regulations, the SAR test may be passed by reducing the maximum transmit power of the terminal device by a larger magnitude. In the embodiment shown in fig. 3, by the arrangement of C301 and C302, a large amount of current on the main radiator can be led to other parasitic radiators, thereby dispersing SAR hot spots. After the SAR hot spot is dispersed, the SAR value can be correspondingly reduced, and the position of the SAR hot spot can not be directly held when a user holds the terminal equipment, so that the maximum transmitting power of the terminal equipment is not required to be reduced by a larger extent in the scene of the head-hand model, the SAR value can meet the regulation requirement only by reducing or not reducing by a smaller extent, the large reduction of TRP is avoided, the uniformity of the reduction of the maximum transmitting power in the scene of the head-hand model at the left side and the right side of the terminal equipment is improved, and the excessive fluctuation of the TRP in different scenes is further avoided.

In the embodiment shown in fig. 3, the first feeding point 306 is illustrated as being located at an end of the first radiating branch 301 near the second radiating branch 302, the second feeding point 309 is illustrated as being located at an end of the third radiating branch 303 near the second radiating branch 302, the third return point 308 is illustrated as being located at an end of the second radiating branch 302 near the third radiating branch 303, and the second return point 307 is illustrated as being located at an end of the second radiating branch 302 near the first radiating branch 301. Alternatively, the fourth return point 311 may be located at an end of the third radiation branch 303 distant from the second radiation branch 302, or at a position near the middle of the third radiation branch 303. Wherein the second feeding point 309 on the third radiating branch 303 is connected to the third return point 308 on the second radiating branch 302 through C302; the second return point 307 on the second radiating branch 302 is connected by C301 and a first feed point 306 on the first radiating branch 301. Alternatively, the first feed point 306 may be connected to feed 1 through C303; the second feed point 309 may be connected to feed 2 through C304 or directly to feed 2. The series capacitances C303 and C304 in fig. 3 are examples of a kind of matching circuit, respectively.

A brief description will be given here of a state in which the antenna is in the zero order mode. The composite left-hand/right-hand transmission line (CRLH-TL) was a new type of left-hand material proposed in 2002 at the earliest, and for the CRLH-TL structure, there is a special non-zero frequency point on the transition section of the left-hand passband and the right-hand passband, where the phase constant β=0 of the electromagnetic wave. If the distribution structure and the matching form of the antenna are properly adjusted, the left-hand transmission line and the right-hand transmission line can have equal characteristic impedance, and a zero-order resonator can be obtained. The resonant frequency of the zero-order resonator is determined by the equivalent inductance and the equivalent capacitance of the composite left-hand and right-hand transmission line, and is irrelevant to the size of the resonator, so that the frequency is irrelevant, and a small-size antenna can be realized. Such zero The order resonator can be made into a zero order resonant antenna. An equivalent schematic diagram for an antenna in the zero order mode (i.e. a zero order resonant antenna) can be seen in fig. 4. FIG. 4 is an illustration of an equivalent schematic diagram of a single radiating branch in the zero-order mode, where Rt is the radiating impedance of the single radiating branch, ΔZ is the internal phase change of the radiating branch, L _R ' equivalent inductance of radiation branch, C _L ' delta Z is equivalent series capacitance of radiation branch, C _L ' Δz is the equivalent parallel capacitance of the radiating branches. The equivalent schematic diagram shown in fig. 4 is applied to the antenna system shown in fig. 3, and the capacitance values of C301 and C302 are adjusted, which is equivalent to the capacitance value of the equivalent series capacitor in the equivalent schematic diagram shown in fig. 4, so that the zero order mode of the antenna system is conveniently constructed, uniform transverse current is formed, the radiation efficiency is improved, SAR hot spots are dispersed, and the amplitude-decreasing equalization of the maximum transmitting power in the scene of the head-hand mode at the left side and the right side of the terminal equipment is improved.

In some embodiments, the first feed point 306 may be located proximate to the first slot 304, i.e., the first feed point 306 is disposed proximate to the first slot 304 (not shown). In some embodiments, the first feeding point 306 may also be disposed at a distance from the first slot 304, e.g., the first feeding point 306 and the first slot 304 are spaced apart by greater than or equal to the first distance threshold, rather than being disposed at the port of the first radiating stub 301 next to the first slot 304. Alternatively, the first distance threshold may be 3 mm, 4 mm, or 5 mm, which is not limited in this embodiment. Optionally, the antenna system further comprises a third capacitor C303, and the first feed point 306 is connected to feed 1 (i.e. the first feed) via a series connection C303. If the first feeding point 306 is disposed in the position close to the first slot 304, the pad (so-called feeding tongue) corresponding to the first feeding point 306 and the spring piece contacting the pad will transfer the strong point of the electric field to the PCB where the pad is located (i.e. the non-headroom area of the antenna) through the first slot 304, and the presence of the PCB will cause a decrease in the performance of the antenna. In this embodiment, by setting the first feeding point 306 to be spaced from the first slot 304 by more than the first distance threshold, and connecting the first feeding point 306 to the feed source 1 through the series connection C303, the first radiating branch 301 may form a left-handed antenna, so as to avoid that the feeding tongue and the shrapnel connected to the first feeding point 306 transfer the strong points of the electric field distributed on the first radiating branch 301 to the non-headroom of the antenna through the first slot 304, thereby avoiding the influence of the existence of the PCB on the antenna performance, and thus ensuring the antenna performance.

In some embodiments, the antenna system may also be as shown in fig. 5, unlike the embodiment shown in fig. 3, in the antenna system shown in fig. 5, the second feeding point 309 is located at an end of the third radiating branch 303 away from the second radiating branch 302, and the fourth return point 311 is located at an end of the third radiating branch 303 close to the second radiating branch 302. In fig. 5, a fourth return location 311 on the third radiating branch 303 is connected by C302 and a third return location 308 on the second radiating branch 302. Alternatively, the first feed point 306 may be connected to feed 1 through C303; the second feed point 309 may be connected to feed 2 through C304. Series capacitances C303 and C304 in fig. 4 are examples of a matching circuit, respectively. In fig. 3, the second feeding point 309 on the third radiating branch 303 is located near one end of the second radiating branch 302, the fourth return point 311 is located far from one end of the second radiating branch 302, and the third radiating branch 303 is solely in the form of a left-hand antenna, and the part from the position of the second feeding point 309 to the position of the fourth return point 311 is used as a main radiator, and the rest is used as a parasitic radiator, so that the main radiator is shorter. In the embodiment shown in fig. 5, when the second feeding point 309 is located at an end far from the second radiating branch 302 and the fourth return point 311 is located at an end near to the second radiating branch 302, the third radiating branch 303 is solely an inverted-F-shaped antenna (IFA), and the entire third radiating branch 303 is a main radiator, which is longer than the third radiating branch 303 in the embodiment of fig. 3, so that the antenna efficiency is improved.

In some embodiments, the feed point or return point of the antenna system may be provided with a multi-pole, multi-throw switch. Wherein, each channel of the multi-pole multi-throw switch can be provided with a matching circuit in different forms to adapt to signals with different frequencies. When the antenna system is excited by signals with different frequencies, the switch can be switched to the corresponding channel to select the matching circuit which enables the current frequency to reach the tuning state, so that the antenna system can reach the resonance mode under the excitation of the signals with different frequencies, the antenna performance of the antenna system at a plurality of frequencies can meet the radiation requirement, and the antenna system has the broadband characteristic. Such as the circuit configuration shown in figures a and b of fig. 6. In the example shown in fig. 6, a is based on fig. 3, a first switch SW1 is provided at a first feeding point 306 and a second return point 307, and a second switch SW2 is provided at a second feeding point 309 and a third return point 308. Fig. 6 b is an example based on fig. 5, in which a first switch SW1 is provided at the first feeding point 306 and the second return point 307, and a second switch SW2 is provided at the third return point 308 and the fourth return point 311. Fig. 6 a and b illustrate that SW1 and SW2 are four-pole four-throw switches, and SW1 includes four channels of channel 1, channel 2, channel 3 and channel 4, and SW2 includes four channels of channel 1, channel 2, channel 3 and channel 4. In practical applications, SW1 and SW2 may also be other multi-pole multi-throw switches, such as a three-pole three-throw switch, a five-pole five-throw switch, etc., and the specific number of channels is not limited in the embodiments of the present application. Optionally, different matching circuits are further disposed on the paths switched by SW1 and SW2, so as to adapt to signals with different frequencies, and the form of the matching circuits on the channels of SW1 and SW2 is not limited in the embodiments of the present application. The form of the matching circuit connected to each channel of SW1 and SW2 in fig. 6 is merely an example, and actually the matching circuits on different channels may be T-type, pi-type, L-type, etc., and specifically may be any one or a combination of multiple forms of series capacitance, series inductance, parallel capacitance, and parallel inductance, which is not limited to the embodiment of the present application.

A fifth return point 312 may also be added to the first radiating stub 301 based on the various embodiments described above. Alternatively, the fifth pass point 312 may be grounded directly through a set of matching circuits or may be grounded through a multiple pole, multiple throw switch. Based on the embodiment shown in fig. 6 a and b, the schematic circuit structures of the fifth return point 312 and the third switch SW3 may be shown in fig. 7 a and b (the matching circuit connected to each path of SW1 and SW2 is omitted in fig. 7). In some embodiments, the fifth return point 312 in fig. 7 may be located between the first return point 310 and the first feed point 306, for example, may be located in the middle of the first radiating branch 301, or may be located near the first return point 310 or near the first feed point 306. In fig. 7, the fifth return point 312 is exemplified by the ground of SW 3. SW3 in fig. 7 may also be a four pole four throw switch, or may be other multiple pole multiple throw switches, and the specific number of channels may be adjusted according to the frequency band supported. The form of the matching circuit respectively connected with each channel of SW3, for example, channel 1, channel 2, channel 3 and channel 4, may be T-type, pi-type, L-type, etc., and specifically may be any one or more of a combination of a plurality of forms of series capacitance, series inductance, parallel capacitance and parallel inductance. The matching circuits to which the different channels of SW3 are connected may be as shown in a diagram of fig. 7. If the antenna system needs to support more frequency bands or the bandwidth occupied by the supported frequency bands is wider, a switch containing more channels can be selected to add various matching circuits to adapt to the more frequency bands; conversely, if the antenna system needs to support fewer frequency bands or the bandwidth occupied by the supported frequency bands is narrow, the switch with fewer channels can be selected, and the requirement of antenna tuning can be met without a plurality of different matching circuits.

On the basis of the above embodiments, the antenna system can also act as a parasitic radiation stub by means of a universal serial bus (universal serial bus, USB) connector on the located terminal device. The housing of the USB connector is of a metal structure and is mounted by solder joints and electrically connected to a reference ground. As shown in fig. 8, the USB connector 313 may be closer to the first side of the second radiating branch 302, and the distance between the two may be less than or equal to the second distance threshold, for example, less than 1 cm or 5 mm, so that signal coupling may be implemented, and the signal coupling may be used as a parasitic radiating branch of the second radiating branch. The first side of the second radiating branch 302 is the side where the second return point 307 and the third return point 308 are located (the side close to the PCB board as shown in fig. 8). In this embodiment, the use of the existing USB connector 313 as the parasitic radiating stub can ensure that the volume of the effective radiator is increased by means of the existing structure of the terminal device without increasing the volume of the antenna system, thereby improving the antenna efficiency.

In some embodiments, the high frequency signal may be, for example, a signal of the B7 band of long term evolution (long term evolution, LTE); the intermediate frequency signal may be, for example, a wideband code division multiple access (wideband code division multiple access, WCDMA) or a signal of a frequency band such as B1, B2, B3 of LTE; the low frequency signal may be, for example, a signal in a frequency band such as B5, B8, or B18 of WCDMA or LTE. Of course, the high-frequency signal may also be a 5G high-frequency signal, the intermediate-frequency signal may also be a 5G intermediate-frequency signal, and the low-frequency signal may also be a 5G low-frequency signal.

In order to more clearly explain the technical effects achieved by the technical solution of the present application, the detailed description will be made using various data obtained by simulation based on the structure and layout of the antenna system shown in fig. 8.

In some embodiments, when the feed source 1 feeds a high-frequency signal, the antenna system may have two resonant modes, wherein the first resonant mode is a resonant mode of the main radiator at the position of the first radiating branch 301, and the current is mainly distributed on the first radiating branch 301; the second resonant mode is a USB branch parasitic mode where current is primarily distributed over the second radiating branch 302. The two resonant modes are resonant modes of high-frequency signals with different frequencies, for example, the first resonant mode may be a resonant mode corresponding to the transmitting frequency of B7, and the second resonant mode may be a resonant mode corresponding to the receiving frequency of B7; for another example, the first resonant mode may be a resonant mode corresponding to the receiving frequency of B7, and the second resonant mode may be a resonant mode corresponding to the transmitting frequency of B7. In fig. 8, the second radiating stub 302 is positioned opposite the USB connector 313, which may be referred to as a USB stub.

The second resonance mode (USB branch parasitic mode) will be described in detail herein. At this time, the USB stub acts as a parasitic radiator, and the current profile can be seen in fig. 9. Based on the embodiment shown in fig. 8, when the feed source 1 feeds a high-frequency signal (such as the signal of B7), if only the second return point 307 is reserved on the second radiating branch 302 and the parasitic mode of the third return point 308 is not reserved, the parasitic mode is an opening-to-back parasitic mode, the equivalent schematic diagram can be seen in fig. 9, and the current distribution diagram can be seen in fig. 9B; if only the third return site 308 is reserved on the second radiating branch 302 and the parasitic mode of the second return site 307 is not reserved as the parasitic mode of the port-to-port, the equivalent schematic diagram can be seen in the graph c in fig. 9, and the current distribution diagram can be seen in the graph d in fig. 9; if the second return location 307 and the third return location 308 are reserved on the second radiation branch 302, the parasitic mode is a parasitic mode of the current loop, the equivalent schematic diagram can be seen in e diagram in fig. 9, and the current distribution diagram can be seen in f diagram in fig. 9. Comparing the three parasitic modes shown in fig. 9, in the parasitic mode of the current loop, the path opened by SW2 may be directly connected to the reference ground (i.e. directly back to ground), and the current is most concentrated on the second radiating branch 302.

The a-graph in fig. 10 is a data comparison graph of different matching forms of whether the path opened by SW2 is a direct ground return. In graph a of fig. 10, the horizontal axis represents frequency in GHz and the vertical axis represents decibel (dB). In fig. 10, F1 represents a match on the path opened by SW2, f1=0 represents a case where the path opened by SW2 is branched back to ground, f1=2pf represents a case where the match on the path opened by SW2 is a capacitance of 2pF in parallel, and data without F1 indicates a case where the path of selected SW2 is open. In graph a of fig. 10, G1 represents the capacitance of the capacitor connected in parallel at the third return point 308, which is only one example. As can be seen from the a-graph in fig. 10, in the case that the SW2 is opened to directly return to the ground, the current on the second radiating branch 302 is most concentrated, and the S11, total Efficiency (TE) and radiating efficiency (radiation efficiency, RE) are improved compared with other matching forms.

Fig. 10 b is a graph comparing data of the fully open mode, the mouth-to-mouth parasitic mode, and the current loop parasitic mode without the return point on the second radiating branch 302. In fig. 10 b, a curve S11-a is a curve of the reflection coefficient corresponding to the mode of the full open circuit where none of the second-loop point and the third-loop point on the second radiation branch is present; the curve S11-B is a curve of reflection coefficient corresponding to the parasitic mode of the third return point on the second radiation branch point, which is connected with 1nH in series and has no second return point; the curve S11-C is a curve of reflection coefficient corresponding to a parasitic mode of a current loop with the second return point and the third return point, wherein the second return point and the third return point are included on the second radiation branch, the second return point is connected with 6nH in series, and the third return point is connected with 6nH in series; the curve RE-A is a curve of radiation efficiency corresponding to a full open circuit mode which is not available in a third return point of the second return point; the curve RE-B is a curve of radiation efficiency corresponding to a third return point on the second radiation branch and is connected in series with 1nH, and no port-to-port parasitic mode of the second return point exists; the curve RE-C is a curve of radiation efficiency corresponding to a parasitic mode of a current loop with the second return point and the third return point, wherein the second return point and the third return point are included on the second radiation branch, the second return point is connected with 6nH in series, and the third return point is connected with 6nH in series. In fig. 10, a and b, the data on the horizontal axis is in GHz and the data on the vertical axis is in dB. As can be seen from the b graph in fig. 10, in the frequency band from 2.5GHz to 2.8GHz, the parasitic mode of the current loop is compared with the parasitic mode of the port-to-port, the total efficiency and the radiation efficiency of the antenna system are improved, and S11 is reduced, so that the performance of the antenna system is improved.

In some embodiments, the second feed point 309 may also be located at a port of the third radiating branch 303 proximate to the second radiating branch 302. Fig. 11 is data obtained by simulation based on the capacitance of 0.6pF in parallel with the second return point 307 and the capacitance of 0.6pF in parallel with the third return point. Under excitation of a high-frequency signal, a graph a in fig. 11 is a current distribution diagram in the case where the second feeding point is grounded (the path of SW2 is not directly grounded but is grounded through a matching circuit), in which the current is mainly distributed on the second radiation branch 302 and part of the current is distributed on the third radiation branch 303; the b-graph in fig. 11 shows the current distribution in the case of the second feed point being grounded (the path of SW2 being directly grounded), in which case the current is mainly distributed over the second radiating branch 302 and the current distributed over the third radiating branch 303 is significantly less. It can be seen that the matching form at the second feeding point can adjust the parasitic mode of the third radiating branch 303, affect the current distribution on the third radiating branch 303, and by setting the second feeding point back to ground, adjust the current concentration on the second radiating branch 302. The graph c in fig. 11 is a data curve in different scenarios. In graph c in fig. 11, curves S11-D are curves of reflection coefficients in the case where the second return point is connected in parallel with 0.6pF, the third return point is connected in parallel with 0.6pF, and the second feeding point is not connected back to ground; the curve S11-E is a curve of the reflection coefficient under the condition that the second return point is connected with 0.6pF in parallel, the third return point is connected with 0.6pF in parallel, and the second feed point returns to the ground; the curve RE-D is a curve of radiation efficiency under the condition that the second return point is connected with 0.6pF in parallel, the third return point is connected with 0.6pF in parallel, and the second feed point is not connected with the ground; the curve RE-E is a curve of radiation efficiency under the condition that the second return point is connected with 0.6pF in parallel, the third return point is connected with 0.6pF in parallel, and the second feed point returns to the ground; curve TE-D is a curve of the total efficiency in the case where the second return point is connected in parallel with 0.6pF and the third return point is connected in parallel with 0.6pF, and the second feeding point is not connected back to ground; curve TE-E is a curve of the total efficiency with the second return point connected in parallel with 0.6pF and the third return point connected in parallel with 0.6pF, the second feed point being connected back to ground. As can be seen from the c-diagram in fig. 11, when the second feeding point is grounded, S11 is reduced, radiation efficiency, and overall efficiency are improved as compared with the case where the second feeding point is not grounded.

Note that, the matching pattern shown in the c-chart in fig. 11 is only an example, and the present embodiment is not limited thereto. It should be noted that, the data related to the embodiment of the present application are all data with good parameters obtained by simulation in a matching form. Based on the antenna system shown in fig. 8, after debugging, the widths of the first slot 304 and the second slot 305 are 1 millimeter, the antenna clearance is 0.8 millimeter, C301 is 0.4pF, C302 is 0.6pF, the matching circuit between the feed source 1 and the first feeding point 306 is a series connection of 1.2pF capacitor, an inductance of 20nH is connected in parallel, the matching circuit between the feed source 2 and the second feeding point 304 is a series connection of 1nH inductor, and a plurality of groups of data are obtained by measurement, which can be seen in the following.

The a diagram in fig. 12 is a current distribution diagram of a conventional antenna scheme (i.e., an original scheme, such as the scheme of the antenna system shown in fig. 2) under signal excitation in the B3 frequency band, and it is obvious that the current is mainly distributed on the radiating branch 3 (corresponding to the first radiating branch 301 in the present application). The B diagram in fig. 12 shows the current distribution diagram of the antenna system (i.e. the new scheme) under the signal excitation of the B3 band, and it can be seen that the current is mainly distributed on the first radiation branch 301 and the second radiation branch 302. In the technical scheme (i.e. the new scheme) of the application, the antenna system can form uniform transverse current on the first radiation branch 301 and the second radiation branch 302 under the excitation of the intermediate frequency signal, and compared with the traditional antenna scheme, the volume of an effective radiator is increased, so that SAR hot spots can be dispersed, and the antenna efficiency of the antenna system in the intermediate frequency band is improved.

Fig. 13, 14 and 15 are graphs of reflection coefficient S11, radiation efficiency and total efficiency of the antenna system in the B3, B1 and B7 frequency bands, respectively, and the horizontal axis in GHz and the vertical axis in dB in fig. 13, 14 and 15. Table 1 is a comparison of the average of the total efficiencies of new scheme (N) and original scheme (O) for B3, B1 and B7 and the bandwidth at sideband efficiency (-6 dB).

As can be seen in conjunction with fig. 13, 14 and 15 and table 1, the overall efficiency is improved by 0.6dB, 0.9dB and 1.4dB, respectively, regardless of B3, B1 or B7; the bandwidths of the side band efficiency of-6 dB are also expanded, and the bandwidths of the side band efficiency of-6 dB of B3, B1 and B7 are respectively increased by 53MHz, 78MHz and 125MHz.

TABLE 1

In another embodiment, the improvement in radiation efficiency within the bandwidth may be seen in fig. 16. In fig. 16, the radiation efficiency of B3, B1, B7 in the left head hand (beside head and hand left, BHHL) and right head hand (beside head and hand right, BHHR) respectively is shown to be improved by 0.5dB to 0.8dB over the original scheme.

The improvement data about the SAR value can be seen in fig. 17, where the data on the vertical axis represents the SAR value, the identification of the horizontal axis characterizes the different frequency bands, and is illustrated in fig. 17 as including B3, B1, and B7. Panel a in FIG. 17 is a graph comparing the 0mm Body SAR values for the original and new protocols at B3, B1 and B7, and panel B in FIG. 17 is a graph comparing the 5mm Body SAR values for the original and new protocols at B3, B1 and B7. For the sake of a clearer comparison of the sizes, the SAR values in fig. 17 are normalized data. As can be seen from the data in fig. 7, in the case of the 0mm Body SAR, the SAR value of B3 of the new scheme is reduced by 0.26, the SAR value of B1 of the new scheme is reduced by 0.54, and the SAR value of B7 of the new scheme is reduced by 0.05, compared with the original scheme, wherein the SAR value of B1 of the new scheme is reduced by 20.6%, and the optimization effect is remarkable. In the 5mm Body SAR scene, compared with the original scheme, the SAR value of B3 of the new scheme is reduced by 0.01, the SAR value of B1 of the new scheme is reduced by 0.06, and the SAR value of B7 of the new scheme is reduced by 0.02, wherein the SAR value of B1 of the new scheme is reduced by 5.88%, and the optimization effect is remarkable.

Examples of the antenna system provided by the present application are described in detail above. It will be appreciated that the corresponding terminal device, in order to implement the above-mentioned functions, comprises corresponding hardware structures for performing the respective functions.

In the several embodiments provided in this application, it should be understood that the disclosed structure may be implemented in other ways. For example, the structural embodiments described above are merely illustrative, e.g., the division of modules or units is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another apparatus, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and the parts shown as units may be one physical unit or a plurality of physical units, may be located in one place, or may be distributed in a plurality of different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An antenna system, comprising: the device comprises a first radiation branch, a second radiation branch and a third radiation branch, wherein a first gap is formed between the first radiation branch and the second radiation branch, and a second gap is formed between the second radiation branch and the third radiation branch;

a first feeding point and a first return point are arranged on the first radiation branch, a second return point and a third return point are arranged on the second radiation branch, and a second feeding point and a fourth return point are arranged on the third radiation branch;

the antenna system further comprises: the first radiation branch is connected with the second radiation branch through the first capacitor, and the second radiation branch is connected with the third radiation branch through the second capacitor;

The first feed point is located at one end of the first radiation branch close to the second radiation branch, and the second feed point is located at one end of the third radiation branch close to the second radiation branch.

2. The antenna system according to claim 1, characterized in that the first feed point is for feeding high frequency signals and/or intermediate frequency signals and the second feed point is for feeding low frequency signals.

3. The antenna system of claim 1, wherein the second return point is located at an end of the second radiating stub that is proximate to the first radiating stub, the second return point and the first feed point being connected by the first capacitance.

4. The antenna system of claim 3, wherein the first return point is located at an end of the first radiating branch remote from the second radiating branch;

the second feed point is located at one end of the third radiation branch close to the second radiation branch, the fourth return point is located at one end of the third radiation branch far away from the second radiation branch, the third return point is located at one end of the second radiation branch close to the third radiation branch, and the second feed point and the third return point are connected through the second capacitor.

5. The antenna system of claim 4, further comprising: a first switch and a second switch;

the first feed point and the second return point are grounded through the first switch;

the second feeding point and the third return point are grounded through the second switch.

6. The antenna system of claim 3, wherein the first return point is located at an end of the first radiating branch remote from the second radiating branch;

the second feed point is located at one end of the third radiation branch, far away from the second radiation branch, the fourth return point is located at one end of the third radiation branch, close to the second radiation branch, the third return point is located at one end of the second radiation branch, close to the third radiation branch, and the third return point and the fourth return point are connected through the second capacitor.

7. The antenna system of claim 6, further comprising: a first switch and a second switch;

the third return point and the fourth return point are grounded through the second switch.

8. An antenna system according to claim 5 or 7, wherein the form of the matching circuit to which each of the paths of the first switch is connected is different and the form of the matching circuit on each of the paths of the second switch is different.

9. The antenna system of claim 3, wherein a fifth return location is further provided on the first radiating stub, the fifth return location being located between the first feed point and the first return location.

10. The antenna system of claim 9, further comprising: a third switch;

the fifth return point is grounded through the third switch.

11. The antenna system of claim 10, wherein the form of the matching circuit to which each path of the third switch is connected is different.

12. The antenna system of claim 3, wherein a distance of the first feed point from the first slot is greater than or equal to a first distance threshold.

13. The antenna system of claim 12, further comprising a third capacitor, wherein the first feed point is coupled to the first feed by connecting the third capacitor in series.

14. The antenna system according to any of claims 1 to 7, 9 to 13, applied to a terminal device comprising a universal serial bus, USB, connector, characterized in that the distance of the first side of the second radiating branch from the USB connector is less than or equal to a second distance threshold, the first side of the second radiating branch being the side where the second return point and the third return point are located.

15. The antenna system according to any of claims 1 to 7, 9 to 13, characterized in that the first capacitance is a distributed parameter capacitance and/or a lumped parameter capacitance, and the second capacitance is a distributed parameter capacitance and/or a lumped parameter capacitance.

16. A terminal device comprising an antenna system according to any of claims 1 to 15.