Antenna and terminal device

Abstract

The invention provides an antenna and terminal equipment, and belongs to the technical field of antennas. The antenna comprises a main radiation branch, a parasitic branch and a switching circuit. The main radiation branch knot is divided into a first radiation branch knot and a second radiation branch knot by the feed point. The end, away from the feed point, of the second radiation branch is grounded, the first radiation branch supports a first frequency band, and the main radiation branch supports a second frequency band and a third frequency band. One end of the parasitic branch and the first radiation branch have a break joint, the other end of the parasitic branch is grounded, and the parasitic branch supports a fourth frequency band shared by Bluetooth, WiFi and cellular networks. Two ends of the switch circuit are respectively connected with the feed point and the radio frequency end. The switch circuit has a first mode, a second mode and a third mode. In the first mode, the second mode and the electrical third mode, the radio frequency end and the antenna are respectively in impedance matching in the first frequency band, the second frequency band and the third frequency band. No matter which mode is in, the radio frequency end is matched with impedance of the parasitic branch knot in the fourth frequency band. And the Bluetooth, the WiFi and the cellular network all have relatively good performance.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of antennas, and in particular to an antenna and a terminal device. BACKGROUND

[0002] An antenna is an important communication device in a terminal device, and is used to be electrically connected with a radio frequency end in the terminal device. When the impedance of the antenna at a certain frequency band matches the impedance of the radio frequency end, the antenna can work at the frequency band. That is, the antenna can convert the electrical signal transmitted by the radio frequency end into electromagnetic waves of the frequency band and radiate to the outside of the terminal device, or the antenna can convert the received electromagnetic waves of the frequency band into electrical signals and transmit to the radio frequency end.

[0003] In the related art, with the development of terminal devices such as smart phones, in order to reduce the size of the antenna in the terminal device, the antenna is designed to be a fusion antenna, that is, the antenna can simultaneously support Bluetooth, WiFi and cellular network. There is a common frequency band among Bluetooth, WiFi and cellular network, and in addition, the cellular network also works at other frequency bands. If the antenna only works at other frequency bands, the performance of Bluetooth and WiFi will be poor.

[0004] Therefore, how to ensure that Bluetooth, WiFi and cellular network have good performance at the same time is a key problem to be solved. SUMMARY

[0005] The present disclosure provides an antenna and a terminal device, which can solve the technical problems existing in the related art. The technical solutions of the antenna and the terminal device are as follows.

[0006] In a first aspect, the present disclosure provides an antenna, which comprises a main radiation branch, a parasitic branch and a switch circuit.

[0007] The main radiation branch has a feed point, the feed point divides the main radiation branch into a first radiation branch and a second radiation branch, one end of the second radiation branch away from the feed point is grounded, the first radiation branch is used to support a first frequency band, and the main radiation branch is used to support a second frequency band and a third frequency band, wherein the first frequency band, the second frequency band and the third frequency band are frequency bands used by a cellular network;

[0008] There is a gap between one end of the parasitic branch and the first radiation branch, and the other end of the parasitic branch is grounded, and the parasitic branch is used to support a fourth frequency band, wherein the fourth frequency band is a common frequency band of Bluetooth, WiFi and cellular network;

[0009] One end of the switch circuit is connected with the feed point, and the other end is connected with a radio frequency end, the switch circuit is used to match the impedance of the radio frequency end and the main radiation branch, and the switch circuit has a first mode, a second mode and a third mode.

[0010] In the first mode, the radio frequency end and the first radiation branch are impedance matched at the first frequency band, and the radio frequency end and the parasitic branch are impedance matched at the fourth frequency band;

[0011] In the second mode, the radio frequency end and the main radiation branch are impedance matched at the second frequency band, and the radio frequency end and the parasitic branch are impedance matched at the fourth frequency band;

[0012] In the third mode, the radio frequency end and the main radiation branch are impedance matched at the third frequency band, and the radio frequency end and the parasitic branch are impedance matched at the fourth frequency band.

[0013] In a possible implementation, the switch circuit comprises a first inductor, a first capacitor, a second inductor, a second capacitor, a first branch and a second branch;

[0014] One end of the first inductor is connected to the feed point, and the other end is grounded, the first capacitor is connected in parallel with the first inductor, the second inductor is connected in series with the first capacitor, one end of the second capacitor is connected to the second inductor, and the other end is grounded, and the second inductor is further connected to the radio frequency end;

[0015] One end of the first branch is connected to the second inductor, and the other end is grounded through the first switch, one end of the second branch is connected to the feed point, and the other end is grounded through the second switch;

[0016] In the first mode, the first switch is closed, and the second switch is opened;

[0017] In the second mode, the first switch is opened, and the second switch is closed;

[0018] In the third mode, the first switch and the second switch are both opened.

[0019] In a possible implementation, the first branch has a third inductor;

[0020] The second branch has a fourth inductor.

[0021] In a possible implementation, the uplink frequency of the second frequency band is 1.92GHz-1.98GHz, and the downlink frequency is 2.11GHz-2.17GHz;

[0022] The switch circuit further comprises a third branch, one end of the third branch is connected to the feed point, and the other end is grounded through a third switch, and the switch circuit further comprises a fourth mode;

[0023] In the second mode, the second switch is closed, the third switch is opened, the radio frequency end and the main radiation branch are impedance matched at the uplink frequency, and the radio frequency end and the parasitic branch are impedance matched at the fourth frequency band, and the antenna is used for transmitting signals.

[0024] In the fourth mode, the second switch is opened, the third switch is closed, the radio frequency end and the main radiation branch are impedance matched at the downlink frequency, and the radio frequency end and the parasitic branch are impedance matched at the fourth frequency band, and the antenna is used for receiving signals.

[0025] In a possible implementation, the third branch has a fifth inductor, the fifth inductor is grounded through the third switch and is in parallel with the fourth inductor, and the inductance value of the fifth inductor is different from the inductance value of the fourth inductor.

[0026] In a possible implementation, the switch circuit further includes a fourth branch, one end of the fourth branch is connected with the feed point, and the other end is grounded through a fourth switch.

[0027] The switch circuit further includes a fifth mode, in the fifth mode, the second switch and the fourth switch are closed, the first switch is opened, the radio frequency end and the main radiation branch are impedance matched at the fifth frequency band, and the radio frequency end and the parasitic branch are impedance matched at the fourth frequency band.

[0028] In a possible implementation, if the length of the first radiation branch is L1, 4mm≤L1≤13mm.

[0029] In a possible implementation, if the length of the first radiation branch is L1, L1=1 / (4λ1), where λ1 is the wavelength of an electromagnetic wave at a first frequency, and the first frequency is within the frequency range of the first frequency band.

[0030] In a possible implementation, if the length of the main radiation branch is L2, 11mm≤L2≤24mm.

[0031] In a possible implementation, if the length of the main radiation branch is L2, L2=1 / (4λ2), where λ2 is the wavelength of an electromagnetic wave at a second frequency, and the second frequency is within the frequency range of the second frequency band or the third frequency band.

[0032] In a possible implementation, if the length of the parasitic branch is L3, 4mm≤L3≤15mm.

[0033] In a possible implementation, a length of the parasitic branch is L3, and L3 = 1 / (4λ3), where λ3 is a wavelength of an electromagnetic wave at a third frequency, and the third frequency is in a frequency range of the fourth frequency band.

[0034] In a second aspect, the present disclosure provides a terminal device, which comprises the antenna according to any one of the first aspect.

[0035] The technical solutions provided by the present disclosure have at least the following beneficial effects:

[0036] The present disclosure provides an antenna, and the switch circuit is in the first mode, the second mode and the third mode, and the antenna can work in the fourth frequency band. In this way, the Bluetooth, WiFi and cellular network can all have good performance. Even if the cellular network works in other frequency bands, the Bluetooth and WiFi can also have good performance.

[0037] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings, which are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure. In the drawings:

[0039] Figure 1 is a structural schematic diagram of an antenna according to an embodiment of the present disclosure;

[0040] Figure 2 is a structural schematic diagram of a switch assembly according to an embodiment of the present disclosure;

[0041] Figure 3 is a schematic diagram of a first mode of a switch assembly according to an embodiment of the present disclosure;

[0042] Figure 4 is a schematic diagram of a second mode of a switch assembly according to an embodiment of the present disclosure;

[0043] Figure 5 is a schematic diagram of a third mode of a switch assembly according to an embodiment of the present disclosure;

[0044] Figure 6 is a structural schematic diagram of a switch assembly according to an embodiment of the present disclosure;

[0045] Figure 7 is a schematic diagram of a second mode of a switch assembly according to an embodiment of the present disclosure;

[0046] Figure 8This is a schematic diagram of a fourth mode of a switching assembly shown in an embodiment of this disclosure;

[0047] Figure 9 This is a schematic diagram of a fifth mode of a switching assembly shown in an embodiment of this disclosure;

[0048] Figure 10 This is a schematic diagram of the structure of a switching assembly shown in an embodiment of this disclosure;

[0049] Figure 11 This is a schematic diagram of the structure of an antenna shown in an embodiment of this disclosure.

[0050] Legend:

[0051] 1. Main radiating branch; 11. First radiating branch; 12. Second radiating branch;

[0052] 2. Parasitic branches;

[0053] 3. Switching circuit, 31. First inductor, 32. First capacitor, 33. Second inductor, 34. Second capacitor, 35. Third inductor, 36. Fourth inductor, 37. Fifth inductor, 38. Sixth inductor;

[0054] 301, First Branch Road; 302, Second Branch Road; 303, Third Branch Road; 304, Fourth Branch Road;

[0055] 3a. First switch; 3b. Second switch; 3c. Third switch; 3d. Fourth switch;

[0056] 100. A crack;

[0057] 200, Feed point;

[0058] 300, Radio Frequency Terminal.

[0059] The accompanying drawings have illustrated specific embodiments of this disclosure, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this disclosure to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings.

[0061] The terms used in the embodiments of the present disclosure are used only to explain embodiments of the present disclosure, and are not intended to limit the present disclosure. Unless otherwise defined, technical terms or scientific terms used herein have the same meaning as understood by those skilled in the art to which the present disclosure belongs. The terms "first", "second", "third", and the like used in the description of the present patent application and the claims are not intended to denote any sequence, quantity, or importance, but are only used to distinguish different components. Similarly, "one" or "a" and the like do not mean a quantity limitation, but mean that at least one exists. "Include" or "contain" and the like mean that the elements or objects appearing before "include" or "contain" cover the elements or objects listed after "include" or "contain" and their equivalents, and do not exclude other elements or objects. "Connected" or "connected" and the like are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right", and the like are only used to represent relative positional relationships, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0062] The antenna is an important communication device in the terminal device, which is electrically connected with the radio frequency end in the terminal device. When the impedance of the antenna at a certain frequency band matches the impedance of the radio frequency end, the antenna can work at the frequency band. That is, the antenna can convert the electrical signal transmitted by the radio frequency end into electromagnetic wave of the frequency band and radiate to the outside of the terminal device, or the antenna can convert the received electromagnetic wave of the frequency band into electrical signal and transmit to the radio frequency end.

[0063] In the related art, with the development of terminal devices such as smart phones, in order to reduce the size of the antenna in the terminal device, the antenna is designed as a fusion antenna, that is, the antenna can simultaneously support Bluetooth, WiFi and cellular network. Among them, there is a common frequency band between Bluetooth, WIFI and cellular network, in addition to which the cellular network also works at other frequency bands. If the antenna only works at other frequency bands, the performance of Bluetooth and WiFi will be poor.

[0064] Therefore, how to ensure that Bluetooth, WiFi and cellular network have good performance at the same time is a key problem to be solved.

[0065] In view of the above technical problems, the present disclosure provides an antenna, such as Figure 1As shown, the antenna comprises a main radiation branch 1, a parasitic branch 2 and a switch circuit 3. The main radiation branch 1 has a feed point 200, which divides the main radiation branch 1 into a first radiation branch 11 and a second radiation branch 12. The second radiation branch 12 is grounded at one end away from the feed point 200, and the first radiation branch 11 is used to support a first frequency band, and the main radiation branch 1 is used to support a second frequency band and a third frequency band. Among them, the first frequency band, the second frequency band and the third frequency band are frequency bands used by the cellular network. The parasitic branch 2 has a gap 100 between one end and the first radiation branch 11, and the other end is grounded, and the parasitic branch 2 is used to support a fourth frequency band. Among them, the fourth frequency band is a shared frequency band of Bluetooth, WiFi and cellular network. One end of the switch circuit 3 is connected with the feed point 200, and the other end is connected with a radio frequency end 300, and the switch circuit 3 is used to match the impedance of the radio frequency end 300 and the main radiation branch 1, and the switch circuit 3 has a first mode, a second mode and a third mode. In the first mode, the radio frequency end 300 and the first radiation branch 11 are impedance matched in the first frequency band, and the radio frequency end 300 and the parasitic branch 2 are impedance matched in the fourth frequency band. In the second mode, the radio frequency end 300 and the main radiation branch 1 are impedance matched in the second frequency band, and the radio frequency end 300 and the parasitic branch 2 are impedance matched in the fourth frequency band. In the third mode, the radio frequency end 300 and the main radiation branch 1 are impedance matched in the third frequency band, and the radio frequency end 300 and the parasitic branch 2 are impedance matched in the fourth frequency band.

[0066] Among them, when the antenna receives a signal, the received electromagnetic wave is converted into an electrical signal and transmitted to the radio frequency end 300. When the antenna transmits a signal, the radio frequency end 300 transmits an electrical signal to the feed point 200, and the antenna converts the electrical signal into an electromagnetic wave and radiates it outward. When the impedance of the first radiation branch 11, the main radiation branch 1 and the parasitic branch 2 matches the impedance of the radio frequency end 300, the antenna can receive or radiate signals of the first frequency band, the second frequency band and the third frequency band, and the fourth frequency band respectively. The impedance of the radio frequency end 300 can be set to 50Ω, and when the impedance of the first radiation branch 11 is close to the impedance of the radio frequency end 300 (such as 48Ω-52Ω), it means that the impedance of the first radiation branch 11 matches the impedance of the radio frequency end 300.

[0067] The parasitic branch 2 is used to support the fourth frequency band, which means that the parasitic branch 2 can best receive or radiate the fourth frequency band, and the parasitic branch 2 can also receive or radiate frequency bands close to the fourth frequency band. Similarly, the first radiation branch 11 can also receive or radiate frequency bands close to the first frequency band, and the main radiation branch 1 can also receive or radiate frequency bands close to the second frequency band and the third frequency band.

[0068] The technical solution provided in this disclosure ensures that the antenna impedance in the fourth frequency band matches the impedance of the RF terminal 300 regardless of the operating state of the switching circuit. Therefore, the antenna can always operate in the fourth frequency band. This enables Bluetooth, WiFi, and cellular networks to all have good performance. Even if the cellular network operates in other frequency bands, Bluetooth and WiFi can still maintain good performance.

[0069] The implementation of switch circuit 3 will be illustrated below.

[0070] In some examples, such as Figure 2 As shown, the switching circuit 3 includes a first inductor 31, a first capacitor 32, a second inductor 33, a second capacitor 34, a first branch 301, and a second branch 302. One end of the first inductor 31 is connected to the feed point 200, and the other end is grounded. The first capacitor 32 is connected in parallel with the first inductor 31, and the second inductor 33 is connected in series with the first capacitor 32. One end of the second capacitor 34 is connected to the second inductor 33, and the other end is grounded. The second inductor 33 is also connected to the RF terminal 300. One end of the first branch 301 is connected to the second inductor 33, and the other end is grounded through the first switch 3a. One end of the second branch 302 is connected to the feed point 200, and the other end is grounded through the second switch 3b.

[0071] like Figure 3 As shown, in the first mode, the first switch 3a is closed and the second switch 3b is open.

[0072] like Figure 4 As shown, in the second mode, the first switch 3a is open and the second switch 3b is closed.

[0073] like Figure 5 As shown, in the third mode, both the first switch 3a and the second switch 3b are open.

[0074] The closing or opening of the first switch 3a and the second switch 3b can adjust the inductance of the switching circuit, thereby adjusting the impedance of the antenna at different frequencies, so that the impedance of the antenna matches the impedance of the RF terminal 300, thus enabling the antenna to switch between different frequency bands.

[0075] For example, such as Figure 2 As shown, the first branch 301 has a third inductor 35, which is grounded through the first switch 3a. The second branch 302 has a fourth inductor 36, which is grounded through the second switch 3b.

[0076] The first frequency band has a frequency range of 2.5GHz-2.7GHz, and the inductance value of the third inductor 35 is less than 0.4nH. Alternatively, a zero-ohm resistor can be used as the third inductor 35.

[0077] In some examples, the uplink frequency of the second frequency band is 1.92 GHz-1.98 GHz, and the downlink frequency is 2.11 GHz-2.17 GHz. The uplink frequency is the frequency range in which the antenna transmits signals of the second frequency band. The downlink frequency is the frequency range in which the antenna receives signals of the second frequency band. Since the second frequency band and the first frequency band are quite different, in order to enhance the effect of the antenna receiving and transmitting the second frequency band, the antenna switches to a different frequency range when receiving and transmitting the second frequency band.

[0078] Therefore, as Figure 6 indicated, the switch circuit 3 further includes a third branch 303. One end of the third branch 303 is connected to the feed point, and the other end is grounded through a third switch 3c. The switch circuit 3 further includes a fourth mode.

[0079] As Figure 7 indicated, in the second mode, the second switch 3b is closed, and the third switch 3c is open. The radio frequency end 300 and the main radiation branch 1 are impedance matched at the uplink frequency, and the radio frequency end 300 and the parasitic branch 2 are impedance matched at the fourth frequency band. The antenna is used for transmitting signals.

[0080] As Figure 8 indicated, in the fourth mode, the second switch 3b is open, and the third switch 3c is closed. The radio frequency end 300 and the main radiation branch 1 are impedance matched at the downlink frequency, and the radio frequency end 300 and the parasitic branch 2 are impedance matched at the fourth frequency band. The antenna is used for receiving signals.

[0081] Exemplarily, as Figure 6 indicated, the third branch 303 has a fifth inductor 37, the fifth inductor 37 is grounded through the third switch 3c, and is connected in parallel with the fourth inductor 36. The inductance value of the fifth inductor 37 is different from the inductance value of the fourth inductor 36. For example, the fifth inductor 37 and the fourth inductor 36 can be 50 nH and 30 nH respectively.

[0082] In some examples, as Figure 6 indicated, the switch circuit 3 further includes a fourth branch 304. One end of the fourth branch 304 is connected to the feed point 200, and the other end is grounded through a fourth switch 3d.

[0083] As Figure 9 indicated, the switch circuit 3 further includes a fifth mode. In the fifth mode, the second switch 3b and the fourth switch 3d are closed, and the first switch 3a is open. The radio frequency end 300 and the main radiation branch 1 are impedance matched at a fifth frequency band, and the radio frequency end 300 and the parasitic branch 2 are impedance matched at the fourth frequency band. The main radiation branch 1 or the first radiation branch 11 is used to support the fifth frequency band. In this way, the bandwidth of the antenna can be increased, thereby improving the performance of the antenna.

[0084] Exemplarily, as Figure 6As shown, the switching circuit also includes a sixth inductor 38, which is grounded through the fourth switch 3d and connected in parallel with the fourth inductor 36. When both the second switch 3b and the fourth switch 3d are closed, the sixth inductor 38 and the fourth inductor 36 are connected in parallel, which reduces the inductance value of the switching circuit, thereby switching the antenna to the fifth frequency band.

[0085] Furthermore, when the switching circuit also includes a fifth inductor 37 and a third switch 3c, both the third switch 3c and the fourth switch 3d can be closed. Since the inductance values ​​of the fifth inductor 37 and the fourth inductor 36 are different, when both the third switch 3c and the fourth switch 3d are closed, the fifth inductor 37 and the fourth inductor 36 can be connected in parallel to produce other inductance values, enabling the antenna to switch to the sixth frequency band.

[0086] Or, such as Figure 10 As shown, the second switch 3b, the third switch 3c, and the fourth switch 3d are all closed, and the fourth inductor 36, the fifth inductor 37, and the sixth inductor 38 are connected in parallel to produce other inductance values, so that the antenna can switch to the seventh frequency band.

[0087] In some examples, the first switch 3a, the second switch 3b, the third switch 3c, and the fourth switch 3d constitute a 4*SPST (four-way single-pole single-throw) switch or a 4PST (four-pole single-throw) switch.

[0088] The structural dimensions of the antenna are illustrated below.

[0089] In some examples, such as Figure 1 As shown, let the length of the first radial branch 11 be L1, then 4mm≤L1≤13mm.

[0090] Specifically, Where c is the speed of electromagnetic wave propagation in vacuum, f1 is the operating frequency of the first frequency band, and ε is the dielectric constant of the terminal device. The frequency range of the first frequency band is 2.5 GHz to 2.7 GHz. Therefore, when calculating L1, f1 can be taken as 2.6 GHz. Taking f1 as the midpoint of the first frequency band ensures that the antenna has good performance at any frequency within the first frequency band.

[0091] In some examples, such as Figure 1 As shown, if the length of the main radiating branch 1 is L2, then 11mm≤L2≤24mm.

[0092] Specifically, Wherein, c is the propagation speed of electromagnetic wave in vacuum, f2 is the operating frequency of the second frequency band or the third frequency band, and ε is the dielectric constant of the terminal device. The uplink frequency of the second frequency band is 1.92GHz-1.98GHz, and the downlink frequency is 2.11GHz-2.17GHz. The uplink frequency of the third frequency band is 1.71GHz-1.78GHz, and the downlink frequency is 1.81GHz-1.88GHz. When calculating L2, the value of f2 can be 1.85GHz. Since the frequency range of the second frequency band and the third frequency band is close, L3 can be calculated according to the frequency of the second frequency band or the frequency of the third frequency band. Then the radiation frequency of the main radiation branch 1 can be adjusted through the switch circuit, so as to realize the switching of the second frequency band and the third frequency band.

[0093] In some examples, as shown in FIG. 1, the length of the parasitic branch 2 is L3, and 4mm≤L3≤15mm. Figure 1

[0094] Specifically, Wherein, c is the propagation speed of electromagnetic wave in vacuum, f1 is the operating frequency of the first frequency band, and ε is the dielectric constant of the terminal device. The frequency range of the fourth frequency band is 2.3GHz-2.4GHz. When calculating L3, the value of f3 can be 2.35GHz. f3 takes the middle value of the fourth frequency band, so that the antenna has good performance at any frequency of the fourth frequency band.

[0095] The embodiments of the present disclosure further provide a terminal device, which comprises the above antenna.

[0096] Wherein, the antenna is arranged in the interior of the terminal device. It can be understood that the parasitic branch 2, the first radiation branch 11 and the second radiation branch 12 can be adaptively arranged according to the collineation in the interior of the terminal device without affecting the performance of the antenna. As shown in FIG. 1, the second radiation branch can be arranged in an L shape to reduce the length of the antenna. Figure 2

[0097] ​​The terminal device in the embodiments of the present application can be a mobile phone, a tablet computer, a notebook computer, a smart bracelet, a smart watch, a smart helmet, smart glasses, etc. The terminal device can also be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a terminal device in a 5G network, or a terminal device in a future evolved Public Land Mobile Network (PLMN), etc., and the embodiments of the present application are not limited thereto.

[0098] The technical solution provided by the embodiments of the present application can enable the antenna to always work in the fourth frequency band, thereby enabling the Bluetooth, WiFi and cellular network to have good performance. In this way, the performance of the terminal device in receiving and sending information can be improved.

[0099] The above only describes optional embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the principles of the present application shall be included in the protection scope of the present application.

Claims

1. An antenna, characterized in that, The antenna includes a main radiating stub (1), a parasitic stub (2), and a switching circuit (3); The main radiating stub (1) has a feed point (200), which divides the main radiating stub (1) into a first radiating stub (11) and a second radiating stub (12). The end of the second radiating stub (12) away from the feed point (200) is grounded. The first radiating stub (11) is used to support a first frequency band, and the main radiating stub (1) is used to support a second frequency band and a third frequency band. The first frequency band, the second frequency band, and the third frequency band are frequency bands used by cellular networks. There is a gap (100) between one end of the parasitic branch (2) and the first radiating branch (11), the other end of the parasitic branch (2) is grounded, and the parasitic branch (2) is used to support a fourth frequency band, wherein the fourth frequency band is a shared frequency band of Bluetooth, WiFi and cellular networks; One end of the switching circuit (3) is connected to the feed point (200), and the other end is connected to the radio frequency terminal (300). The switching circuit (3) is used to perform impedance matching between the radio frequency terminal (300) and the main radiating stub (1). The switching circuit (3) has a first mode, a second mode and a third mode. In the first mode, the RF terminal (300) and the first radiating stub (11) are impedance matched in the first frequency band, and the RF terminal (300) and the parasitic stub (2) are impedance matched in the fourth frequency band. In the second mode, the RF terminal (300) and the main radiating stub (1) are impedance matched in the second frequency band, and the RF terminal (300) and the parasitic stub (2) are impedance matched in the fourth frequency band. In the third mode, the RF terminal (300) and the main radiating stub (1) are impedance matched in the third frequency band, and the RF terminal (300) and the parasitic stub (2) are impedance matched in the fourth frequency band.

2. The antenna according to claim 1, characterized in that, The switching circuit (3) includes a first inductor (31), a first capacitor (32), a second inductor (33), a second capacitor (34), a first branch (301), and a second branch (302); One end of the first inductor (31) is connected to the feed point (200), and the other end is grounded. The first capacitor (32) is connected in parallel with the first inductor (31). The second inductor (33) is connected in series with the first capacitor (32). One end of the second capacitor (34) is connected to the second inductor (33), and the other end is grounded. The second inductor (33) is also connected to the radio frequency terminal (300). One end of the first branch (301) is connected to the second inductor (33), and the other end is grounded through the first switch (3a). One end of the second branch (302) is connected to the feed point (200), and the other end is grounded through the second switch (3b). In the first mode, the first switch (3a) is closed and the second switch (3b) is open; In the second mode, the first switch (3a) is open and the second switch (3b) is closed; In the third mode, both the first switch (3a) and the second switch (3b) are open.

3. The antenna according to claim 2, characterized in that, The first branch (301) has a third inductor (35), which is grounded through the first switch (3a); The second branch (302) has a fourth inductor (36), which is grounded through the fourth inductor (36).

4. The antenna according to claim 3, characterized in that, The uplink frequency of the second frequency band is 1.92GHz-1.98GHz, and the downlink frequency is 2.11GHz-2.17GHz; The switching circuit (3) further includes a third branch (303), one end of which is connected to the feed point, and the other end is grounded through a third switch (3c). The switching circuit (3) also includes a fourth mode. In the second mode, the second switch (3b) is closed, the third switch (3c) is open, the RF terminal (300) and the main radiating stub (1) are impedance matched at the uplink frequency, and the RF terminal (300) and the parasitic stub (2) are impedance matched at the fourth frequency band, and the antenna is used to transmit signals; In the fourth mode, the second switch (3b) is open, the third switch (3c) is closed, the RF terminal (300) and the main radiating stub (1) are impedance matched at the downlink frequency, and the RF terminal (300) and the parasitic stub (2) are impedance matched at the fourth frequency band, and the antenna is used to receive signals.

5. The antenna according to claim 4, characterized in that, The third branch (303) has a fifth inductor (37), which is grounded through the third switch (3c) and connected in parallel with the fourth inductor (36). The inductance value of the fifth inductor (37) is different from that of the fourth inductor (36).

6. The antenna according to claim 2, characterized in that, The switching circuit (3) further includes a fourth branch (304), one end of which is connected to the feed point (200), and the other end is grounded through the fourth switch (3d); The switching circuit (3) further includes a fifth mode in which the second switch (3b) and the fourth switch (3d) are closed, the first switch (3a) is open, the radio frequency terminal (300) and the main radiating stub (1) are impedance matched in the fifth frequency band, and the radio frequency terminal (300) and the parasitic stub (2) are impedance matched in the fourth frequency band.

7. The antenna according to any one of claims 1-6, characterized in that, Let the length of the first radiating branch (11) be L1, then 4mm≤L1≤13mm.

8. The antenna according to claim 1, characterized in that, Let the length of the main radiating branch (1) be L2, then 11mm≤L2≤24mm.

9. The antenna according to any one of claims 1-6, characterized in that, Let the length of the parasitic branch (2) be L3, then 4mm≤L3≤15mm.

10. A terminal device, characterized in that, The terminal device includes the antenna as described in any one of claims 1-9.

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