HK1233771B - Antenna and mobile terminal - Google Patents

Description

Antenna and mobile terminal

Technical Field

The present invention relates to the field of antenna technology, and in particular to an antenna and a mobile terminal.

Background Art

With the advent of LTE (Long Term Evolution), the fourth generation of mobile communications, bandwidth requirements for mobile devices, such as cell phones, are increasing. Designing an antenna with a wide bandwidth that can meet current and future 2G/3G/4G communications requirements is a significant challenge, given the increasing thinness of cell phones and the limited space available for antennas. This is particularly true when it comes to antenna bandwidth that covers low-frequency bands (698-960MHz) while also meeting the requirements of cell phone miniaturization.

Some existing antenna solutions in mobile phones, such as planar inverted-F antennas (PIFA), inverted-F antennas (IFA), monopole antennas, T-type antennas, and loop antennas, are difficult to miniaturize because the antenna length must be at least one-quarter to one-half of the low-frequency wavelength.

Summary of the Invention

Embodiments of the present invention provide an antenna and a mobile terminal capable of reducing size.

An embodiment of the present invention provides an antenna, including a first radiating portion, a matching circuit, and a feed source. The first radiating portion includes a first radiator, a second radiator, and a capacitor structure. The first end of the first radiator is connected to the feed source through the matching circuit, and the feed source is connected to a ground portion. The second end of the first radiator is connected to the first end of the second radiator through the capacitor structure, and the second end of the second radiator is connected to the ground portion. The first radiating portion is used to generate a first resonant frequency, and the length of the second radiator is one-eighth of the wavelength of the first resonant frequency.

In a first possible implementation manner, the first end of the second radiator and the second end of the first radiator are close to each other and maintain a distance therebetween, so as to form the capacitor structure.

In a second possible implementation, the capacitance structure is a capacitor, and the second end of the first radiator is connected to the first end of the second radiator through the capacitance structure. Specifically, the second end of the first radiator is connected to the first end of the second radiator through the capacitor.

In a third possible implementation, the capacitor structure includes a first branch structure and a second branch structure, the first branch structure includes at least a pair of first branches parallel to each other, the second branch structure includes at least one second branch, there is a gap between the first branches and the first branches, and the second branch is located between the two first branches and has a gap with the first branch.

In combination with any one of the above possible implementations, in a fourth possible implementation, the antenna further includes a second radiating portion, a first end of the second radiating portion is connected to the second end of the first radiator, and the second radiating portion and the capacitor structure generate a first high-frequency resonant frequency.

In combination with any one of all the above possible implementations, in a fifth possible implementation, the antenna also includes a third radiating portion, the first end of the third radiating portion is connected to the first end of the second radiator, and the third radiating portion and the capacitor structure generate a second high-frequency resonant frequency.

In combination with any one of all the above possible implementations, in a sixth possible implementation, the antenna also includes a fourth radiating portion, the first end of the fourth radiating portion is connected to the first end of the second radiator, and the fourth radiating portion and the capacitor structure generate a low-frequency resonant frequency and a high-order resonant frequency.

On the other hand, the present invention provides a mobile terminal, comprising an antenna, a radio frequency processing unit and a baseband processing unit, wherein:

The antenna includes a first radiating portion, a matching circuit, and a feed power source. The first radiating portion includes a first radiator, a second radiator, and a capacitor structure. The first end of the first radiator is connected to the feed power source via the matching circuit, and the feed power source is connected to a ground portion. The second end of the first radiator is connected to the first end of the second radiator via the capacitor structure, and the second end of the second radiator is connected to the ground portion. The first radiating portion is configured to generate a first resonant frequency, and the length of the second radiator is one-eighth of the wavelength of the first resonant frequency.

The baseband processing unit is connected to the power feeder via the radio frequency processing unit;

The antenna is used to transmit the received wireless signal to the RF processing unit, or convert the transmission signal of the RF processing unit into electromagnetic waves and send them out; the RF processing unit is used to perform frequency selection, amplification, and down-conversion on the wireless signal received by the antenna, and convert it into an intermediate frequency signal or a baseband signal and send it to the baseband processing unit, or to up-convert and amplify the baseband signal or intermediate frequency signal sent by the baseband processing unit and send it out through the antenna; the baseband processing unit processes the received intermediate frequency signal or the baseband signal.

In a first possible implementation manner, the first end of the second radiator and the second end of the first radiator are close to each other and maintain a distance therebetween, thereby forming the capacitor structure.

In a second possible implementation, the capacitance structure is a capacitor, and the second end of the first radiator is connected to the first end of the second radiator through the capacitance structure. Specifically, the second end of the first radiator is connected to the first end of the second radiator through the capacitor.

In a third possible implementation, the capacitor structure includes a first branch structure and a second branch structure, the first branch structure includes at least a pair of first branches parallel to each other, the second branch structure includes at least one second branch, there is a gap between the first branches and the first branches, and the second branch is located between the two first branches and has a gap with the first branch.

In combination with any of the above embodiments, in a fourth possible implementation, the antenna also includes a second radiating portion, a first end of the second radiating portion is connected to the second end of the first radiator, and the second radiating portion and the capacitor structure generate a first high-frequency resonant frequency.

In combination with any of the above embodiments, in a fifth possible implementation, the antenna also includes a third radiating portion, the first end of the third radiating portion is connected to the first end of the second radiator, and the third radiating portion and the capacitor structure generate a second high-frequency resonant frequency.

In combination with any of the above embodiments, in a sixth possible implementation method, the antenna also includes a fourth radiating portion, the first end of the fourth radiating portion is connected to the first end of the second radiator, and the fourth radiating portion and the capacitor structure generate a low-frequency resonant frequency and a high-order resonant frequency.

In a seventh possible implementation, the first radiating portion is located on the antenna support.

The antenna and mobile terminal provided by the embodiments of the present invention utilize the first end and the second end of the second radiator to form a parallel distributed inductor in the principle of a composite left-handed transmission line, and the capacitance structure is a series distributed capacitance structure in the principle of the composite left-handed transmission line, so that the length of the second radiator is one-eighth of the low-frequency wavelength, thereby reducing the length of the antenna and further reducing the volume of the mobile terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

FIG1 is a schematic diagram of an antenna provided by a first embodiment of the present invention;

FIG2 is a schematic diagram of an equivalent circuit of the antenna shown in FIG1 ;

FIG3 is a schematic diagram of the resonant frequency generated by the antenna shown in FIG1 ;

FIG4 is a schematic diagram of an antenna provided in a second embodiment of the present invention;

FIG5 is a schematic diagram of an antenna provided in a third embodiment of the present invention;

FIG6 is a schematic diagram of an antenna provided in a fourth embodiment of the present invention;

FIG7 is a schematic diagram of the resonant frequency generated by the antenna shown in FIG6;

FIG8 is a frequency response diagram of the antenna shown in FIG6;

FIG9 is a diagram of the radiation efficiency of the antenna shown in FIG6 ;

10 is a schematic diagram of an assembly of a circuit board and an antenna of a mobile terminal provided by the present invention;

FIG11 is another schematic diagram of the assembly of the circuit board and antenna of the mobile terminal provided by the present invention.

DETAILED DESCRIPTION

The technical solutions in the embodiments of the present invention will be clearly described below with reference to the accompanying drawings in the embodiments of the present invention.

Referring to Figure 1 , an antenna 100 according to a first embodiment of the present invention includes a first radiating portion 30, a matching circuit 20, and a power supply 40. The first radiating portion 30 includes a first radiator 34, a second radiator 32, and a capacitor structure located between the first radiator 34 and the second radiator 32 (the capacitor structure is not labeled in Figure 1 ; see 36a in Figure 4 and 36c in Figure 6 , both of which are capacitor structures). A first end of the first radiator 34 is connected to the power supply 40 via the matching circuit 20, and the power supply 40 is connected to the ground portion 10. A second end of the first radiator 34 is connected to a first end of the second radiator 32 via the capacitor structure, and a second end of the second radiator 32 is connected to the ground portion 10. The first radiating portion 30 is configured to generate a first resonant frequency, and the length of the second radiator 32 is one-eighth the wavelength of the first resonant frequency. The first resonant frequency may correspond to f1 in Figures 3 and 7 .

The first resonant frequency may be a low-frequency resonant frequency.

The antenna 100 provided in an embodiment of the present invention utilizes the first end and the second end of the second radiator 32 to form a parallel distributed inductor in the principle of a composite left-handed transmission line, and the capacitance structure is a series distributed capacitance structure in the principle of the composite left-handed transmission line, so that the length of the second radiator 32 is one eighth of the low-frequency wavelength, thereby reducing the length of the antenna 100.

The second end of the second radiator 32 is connected to the ground portion 10. The capacitor structure is designed between the second end of the first radiator 34 and the first end of the second radiator 32, and is connected in series with the second radiator 32. The second radiator 32 and the capacitor structure generate a low-frequency resonant frequency. For an antenna, the factors that determine the resonant frequency include capacitance and inductance. The second radiator 32 is equivalent to an inductor, so the second radiator 32 and the capacitor structure generate a low-frequency resonant frequency. As shown in Figure 1, the first radiator 34, the second radiator 32, and the capacitor structure together form the core components of the left-handed transmission line principle. The signal flow path passes through the capacitor structure and then through the parallel inductor to connect to the ground portion 10, forming a left-handed transmission structure. Among them, the first end and the second end of the second radiator 32 constitute a parallel distributed inductor in the left-hand transmission line principle, and the capacitance structure is a series distributed capacitance structure in the left-hand transmission line principle. Its equivalent circuit diagram is shown in Figure 2. According to the left-hand transmission line principle, the length of the second radiator 32 is one-eighth of the low-frequency wavelength, that is, the length of the antenna 100 is one-eighth of the low-frequency wavelength. Compared with the antenna length of the prior art, which must be at least one-quarter to one-half of the low-frequency wavelength, the antenna 100 of the embodiment of the present invention has the advantage of small size.

Specifically, the capacitor structure and the distributed inductance between the second end and the first end of the second radiator 32 conform to the left-hand transmission line principle, and the generated first resonant frequency (for example, the first resonant frequency can be a low-frequency resonant frequency) f1, please refer to Figure 3. Since the factors that determine the size of the first resonant frequency include capacitance value and inductance value, the resonant frequency can be adjusted by changing the length of the distributed inductance between the first end and the second end of the second radiator 32, and the resonant frequency can also be fine-tuned by changing the size of the series distributed capacitor structure.

Furthermore, if the first resonant frequency (low-frequency resonant frequency) of the antenna 100 needs to be lowered, the gap in the capacitor structure needs to be reduced and/or the inductance value needs to be increased. For example, by reducing the distance between the second end of the first radiator 34 and the first end of the second radiator 32, the capacitor structure value can be increased. By increasing the length between the first and second ends of the second radiator 32, the distributed inductance value between the first and second ends of the second radiator 32 can be increased. If the first resonant frequency (low-frequency resonant frequency) of the antenna 100 needs to be adjusted toward a high-frequency resonant frequency, the gap in the capacitor structure needs to be increased and/or the inductance value needs to be reduced. For example, by increasing the distance between the second end of the first radiator 34 and the first end of the second radiator 32, the capacitor structure value can be reduced. By reducing the length between the first and second ends of the second radiator 32, the distributed inductance value between the first and second ends of the second radiator 32 can be reduced.

In one embodiment of the present invention, as shown in FIG1 , the first end of the second radiator 32 and the second end of the first radiator 34 are close to each other and maintain a distance therebetween, thereby forming the capacitor structure.

In another embodiment of the present invention, as shown in Figure 4, the capacitor structure 36a can be a capacitor (the capacitor can be a separate electronic component), and the second end of the first radiator 34 is connected to the first end of the second radiator 32 through the capacitor structure 36a. Specifically, the second end of the first radiator 34 is connected to the first end of the second radiator 32 through the capacitor.

As shown in FIG1 , in an optional embodiment, the first radiator 34 and the second radiator 32 may be microstrip lines disposed on a circuit board 200. In this case, the first radiating portion 30, the matching circuit 20, and the ground portion 10 are all disposed on the circuit board, that is, the first radiating portion 30, the matching circuit 20, and the ground portion 10 may be disposed in the same plane of the circuit board 200.

In other embodiments, the first radiator 34 and the second radiator 32 may also be metal sheets. In this case, the first radiator 34 and the second radiator 32 may be formed on a bracket, and the bracket is an insulating medium as shown in Figure 10. Optionally, the first radiator 34 and the second radiator 32 may also be suspended.

It should be understood that the embodiment of the present invention does not limit the shape of the second radiator 32. The second radiator 32 may be substantially L-shaped. In other embodiments, the second radiator 32 may be C-shaped, M-shaped, S-shaped, W-shaped, N-shaped, or other serpentine shapes. The serpentine shape of the second radiator 32 can further shorten the length of the second radiator 32, thereby further reducing the size of the antenna 100.

As shown in FIG1 , in an optional embodiment, the grounding portion 10 is the ground of the circuit board 200. In other embodiments, the grounding portion 10 may also be a grounding metal plate.

Please refer to Figure 3, which shows a frequency-standing wave ratio (VSWR) graph (frequency response graph) of antenna 100 shown in Figure 1. The horizontal axis represents frequency (Frequency, abbreviated as Freq) in gigahertz (GHz), and the vertical axis represents VSWR. The first resonant frequency (low-frequency resonant frequency) f1 generated by antenna 100 shown in Figure 1 is approximately 800 MHz (megahertz).

Please refer to Figure 4, which is an antenna 100a according to a second embodiment of the present invention. The antenna 100a provided in the second embodiment has a structure substantially the same as that of the antenna 100 provided in the first embodiment (please refer to Figure 1), and performs similar functions. The difference is that a capacitor structure 36a is connected between the second end of the first radiator 34a and the first end of the second radiator 32a. In an optional embodiment, the capacitor structure 36a may be a multilayer capacitor or a distributed capacitor. In other embodiments, the capacitor structure 36a may be a variable capacitor or a plurality of capacitors connected in series or in parallel. The capacitor structure 36a may be a variable capacitor, so that the value of the variable capacitor may be changed according to actual needs, so that the low-frequency resonant frequency of the antenna 100 of the present invention may be changed by adjusting the value of the variable capacitor, thereby improving the convenience of use.

Please refer to Figure 5, which shows an antenna 100b according to a third embodiment of the present invention. The antenna 100b provided in the third embodiment has a substantially identical structure to the antenna 100 provided in the first embodiment (see Figure 1), and performs similar functions. The difference lies in that the capacitor structure 36b includes a first branch structure 35b and a second branch structure 37b. The first branch structure 35b includes at least a pair of mutually parallel first branches 350b, and the second branch structure 37b includes at least one second branch 370b. The first branches 350b have gaps between them, and the second branch 370b is located between the first branches 350b and has a gap with the first branch 350b. In other words, the capacitor structure 36b is formed by the first branches 350b and the second branches 370b.

As shown in Figure 5, in an optional embodiment, there are two first branches 350b that are parallel to each other, and there is a certain gap between two adjacent first branches 350b. There are three second branches 370b that are parallel to each other, and one first branch 350b is inserted between two adjacent second branches 370b.

In other embodiments, the number of first branches 350b may be four or more, but each two adjacent first branches 350b have a certain gap between them and are parallel to each other. Meanwhile, the number of second branches 370b may be three or more, with each first branch 350b inserted between two adjacent second branches 370b. In general, each two adjacent second branches 370b have a certain gap between them and are parallel to each other, and each first branch 350b is inserted between two adjacent second branches 370b. Furthermore, the number of second branches 370b is one more than the number of first branches 350b. Of course, the reverse is also possible, that is, the number of first branches 350b is one more than the number of second branches 370b, and each two adjacent first branches 350b have a certain gap between them and are parallel to each other, and each second branch 370b is inserted between two adjacent first branches 350b.

Please refer to Figure 6, which is an antenna 100c of the fourth embodiment of the present invention. The antenna 100c provided in the fourth embodiment has basically the same structure as the antenna 100b provided in the third embodiment (please refer to Figure 5), and the functions implemented are similar. The difference is that the antenna 100c also includes a second radiating portion 39c, and the first end of the second radiating portion 39c is connected to the second end of the first radiator 34c. The second radiating portion 39c and the capacitor structure 36c generate a first high-frequency resonant frequency, as shown in Figure 7. The first high-frequency resonant frequency can correspond to f6 in Figure 7.

As a further improvement of the present invention, the antenna 100c further includes at least one third radiating portion 38c. A first end of the third radiating portion 38c is connected to a first end of the second radiator 32c. The third radiating portion 38c and the capacitor generate a second high-frequency resonant frequency, wherein the second high-frequency resonant frequency may correspond to f4 or f5 in FIG. 7 . In this embodiment, the antenna 100c includes two third radiating portions 38c, each generating two second high-frequency resonant frequencies, corresponding to f4 and f5 in FIG. 7 , respectively. One of the third radiating portions 38c is located between the other third radiating portion 38c and the second radiating portion 39c. That is, one third radiating portion 38c is close to the second radiating portion 39c, while the other third radiating portion 38c is further away from the second radiating portion 39c. The third radiating portion 38c closer to the second radiating portion 39c may correspond to the second high-frequency resonant frequency f5, while the third radiating portion 38c further away from the second radiating portion 39c may correspond to the second high-frequency resonant frequency f4.

It is understood that in this embodiment, the third radiating portion 38c away from the second radiating portion 39c corresponds to the second high-frequency resonant frequency f4, the third radiating portion 38c close to the second radiating portion 39c corresponds to the second high-frequency resonant frequency f5, and the second radiating portion 39c corresponds to the first high-frequency resonant frequency f6. Optionally, f4 may correspond to the third radiating portion 38c or the second radiating portion 39c close to the second radiating portion 39c, f5 may correspond to the third radiating portion 38c and the second radiating portion 39c away from the second radiating portion 39c, and f6 may correspond to the second high-frequency resonant frequency f4 of the third radiating portion 38c away from the second radiating portion 39c or the second high-frequency resonant frequency f5 of the third radiating portion 38c close to the second radiating portion 39c. Specifically, how f4-f6 correspond to the third radiating portion 38c away from the second radiating portion 39c, the third radiating portion 38c near the second radiating portion 39c, and the second radiating portion 39c can be determined based on the lengths of the third radiating portion 38c away from the second radiating portion 39c and the third radiating portion 38c near the second radiating portion 39c. The longer the length, the lower the corresponding frequency. For example, if the third radiating portion 38c near the second radiating portion 39c is longer than the second radiating portion 39c, and the second radiating portion 39c is longer than the third radiating portion 38c away from the second radiating portion 39c, then the third radiating portion 38c near the second radiating portion 39c corresponds to f4, the second radiating portion 39c corresponds to f5, and the length of the third radiating portion 38c away from the second radiating portion 39c corresponds to f6.

Optionally, each third radiating portion 38c is in a “匚” shape, and the two third radiating portions 38c form two parallel branches, and the two have a common endpoint, which is connected to the first end of the second radiator 32c.

As a further improvement of the embodiment of the present invention, one end of the fourth radiating portion 37 c is connected to the first end of the second radiator 32 c , and the other end of the fourth radiating portion 37 c is in an open state.

Optionally, the fourth radiating portion 37c and the second radiator 32c may be located on the same side of the capacitor structure 36c.

The fourth radiation portion 37 c and the capacitor structure 36 c generate a low-frequency resonance frequency and a high-order resonance frequency, wherein the low-frequency resonance frequency may correspond to f2 in FIG. 7 , and the high-order resonance frequency may correspond to f3 in FIG. 7 .

Optionally, the fourth radiation portion 37c is in a “匚” shape.

In an optional embodiment, the fourth radiating portion 37c is opposite to one of the third radiating portions 38c (for example, the third radiating portion 38c away from the second radiating portion 39c), and the open end of the fourth radiating portion 37c is opposite to and does not contact the open end of one of the third radiating portions 38c to form a coupling structure. It can be understood that the open end of the fourth radiating portion 37c is opposite to and does not contact the open end of one of the third radiating portions 38c, and may not form a coupling structure.

In other embodiments, the antenna 100 of the fourth embodiment may include only the second radiating portion 39c and/or at least one third radiating portion 38c and/or the fourth radiating portion 37c in addition to the first radiator 34 and the second radiator 32. That is, the second radiating portion 39c, the third radiating portion 38c, and the fourth radiating portion 37c may be combined in any manner. The number of second radiating portions 39c, third radiating portions 38c, and fourth radiating portions 37c may also be increased or decreased based on actual needs.

The antenna 100 can generate multiple resonant frequencies as shown in Figure 7, where f1 is the low-frequency resonant frequency generated by the second radiator 32c as the first resonant frequency, f2 is the low-frequency resonant frequency generated by the fourth radiating part 37c, f3 is the high-order resonant frequency generated by the fourth radiating part 37c, f4 and f5 are the second high-frequency resonant frequencies generated by the two third radiating parts 38c, and f6 is a high-frequency resonant frequency generated by the second radiating part 39c, so that the antenna 100 of the embodiment of the present invention is a wide antenna 100 that can cover high and low frequencies.

Resonant frequencies f1 and f2 can cover the low frequency bands of GSM/WCDMA/UMTS/LTE, resonant frequency f3 is used to cover the frequency band LTE B21, and high-frequency resonant frequencies f4, f5, and f6 cover the high frequency bands of DCS/PCS/WCDMA/UMTS/LTE.

In an optional embodiment, f1=800MHz, f2=920MHz, f3=1800MHz, f4=2050MHz, f5=2500MHz, and f6=2650MHz. In other words, the low frequency of the antenna 100 of the present invention covers the 800MHz-920MHz frequency band, and the high frequency covers the 1800MHz-2650MHz frequency band.

Figure 8 is a frequency-standing wave ratio (VSWR) graph (frequency response graph) for antenna 100c shown in Figure 6 , where the abscissa represents frequency (Frequency, abbreviated as Freq) in gigahertz (GHz), and the ordinate represents VSWR in decibels (dB). Figure 8 shows that antenna 100 can excite dual low-frequency resonances, which, combined with multiple high-frequency resonances, generate broadband high-frequency coverage.

FIG9 is a graph showing the radiation efficiency of the antenna 100 shown in FIG6 , wherein the horizontal axis represents frequency and the vertical axis represents gain. FIG9 shows that the radiation efficiency of the antenna 100c is relatively good.

In summary, the antenna 100c of the present invention can generate low-frequency resonant frequencies and high-frequency resonant frequencies. The low-frequency frequency can cover the 800MHz-920MHz frequency band, and the high-frequency frequency can cover the 1800MHz-2650MHz frequency band. By adjusting the distributed inductance and series capacitance, the resonant frequency can cover the frequency band required by the current 2G/3G/4G communication system.

Furthermore, since the second end of the first radiator 34c is electrically connected to the first end of the second radiator 32c via the capacitor structure 36c, the antenna 100c can generate different resonant frequencies by adjusting the position of the capacitor structure 36c between the second end of the first radiator 34c and the first end of the second radiator 32c. Specifically, the size of the capacitor structure can be determined by the area of the metal plates, the distance between the two parallel metal plates, and the dielectric constant of the medium between the two parallel metal plates. The calculation formula is: C = er * A / d, where C is the capacitance value, er is the dielectric constant of the medium between the two parallel metal plates, A is the cross-sectional area of the two parallel metal plates, and d is the distance between the two parallel metal plates. Therefore, the capacitance value can be adjusted by adjusting the values of er, A, and d.

Please refer to FIG. 10 and FIG. 11 , which illustrate a mobile terminal provided by an embodiment of the present invention. The mobile terminal may be an electronic device such as a mobile phone, a tablet computer, or a personal digital assistant.

The mobile terminal 300 of the present invention includes an antenna 100, a radio frequency processing unit, and a baseband processing unit. The radio frequency processing unit and the baseband processing unit can be arranged on a circuit board 300. The baseband processing unit is connected to the feed power source 40 of the antenna 100 through the radio frequency processing unit. The antenna 100 is used to transmit the received wireless signal to the radio frequency processing unit, or convert the transmission signal of the radio frequency processing unit into an electromagnetic wave and send it out; the radio frequency processing unit is used to perform frequency selection, amplification, and down-conversion processing on the wireless signal received by the antenna, and convert it into an intermediate frequency signal or a baseband signal and send it to the baseband processing unit, or to up-convert and amplify the baseband signal or intermediate frequency signal sent by the baseband processing unit and send it out through the antenna; the baseband processing unit processes the received intermediate frequency signal or the baseband signal.

The antenna in the mobile terminal can be any of the antennas in the above-mentioned antenna embodiments. The baseband processing unit can be connected to the circuit board. As shown in Figure 10, in one embodiment, the first radiating portion 30 of the antenna 100 can be located on the antenna bracket 200. The antenna bracket 200 can be an insulating medium, arranged on one side of the circuit board 300, arranged in parallel with the circuit board 300, or fixed on the circuit board 300. Optionally, the first radiating portion 30 of the antenna can also be in a suspended state (as shown in Figure 11), wherein the second radiating portion 39c, the third radiating portion 38c and the fourth radiating portion 37c can also be located on the antenna bracket 200. Of course, the second radiating portion 39c, the third radiating portion 38c and the fourth radiating portion 37c can also be in a suspended state.

The mobile terminal provided in an embodiment of the present invention utilizes the first end and the second end of the second radiator 32 of the antenna 100 to form a parallel distributed inductor in the composite left-handed transmission line principle, and the capacitance structure is a series distributed capacitance structure in the composite left-handed transmission line principle, so that the length of the second radiator 32 is one eighth of the low-frequency wavelength, thereby reducing the length of the antenna 100 and further reducing the volume of the mobile terminal.

The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims (25)

1. An antenna, characterized in that: the antenna includes a first radiating part, a matching circuit, and a power supply; the first radiating part includes a first radiator, a second radiator, and a capacitor structure; a first end of the first radiator is connected to the power supply through the matching circuit; the power supply is connected to a ground; a second end of the first radiator is connected to the first end of the second radiator through the capacitor structure; and a second end of the second radiator is connected to the ground; wherein the first radiating part is used to generate a first resonant frequency; the length of the second radiator is one-eighth of the wavelength corresponding to the first resonant frequency; wherein a left-handed transmission structure is formed by the signal flow path passing through the capacitor structure and then through a parallel distributed inductor connected to the ground; wherein the parallel distributed inductor between the first end and the second end of the second radiator constitutes the left-handed transmission structure; and wherein the first resonant frequency can be adjusted by changing the length of the distributed inductor between the first end and the second end of the second radiator or by changing the value of the capacitor structure. 2. The antenna as claimed in claim 1, wherein the first end of the second radiator and the second end of the first radiator are close to each other and maintain a distance, forming the capacitor structure. 3. The antenna as described in claim 1, wherein the capacitor structure is a capacitor. 4. The antenna as claimed in claim 1, wherein the capacitor structure comprises a first branch structure and a second branch structure, the first branch structure comprises at least a pair of parallel first branches, the second branch structure comprises at least one second branch, the first branches have a gap between them, and the second branch is located between the two first branches and has a gap with the first branches. 5. The antenna according to any one of claims 1-4, wherein the antenna further comprises a second radiating part, a first end of the second radiating part is connected to a second end of the first radiating body, and the second radiating part and the capacitor structure generate a first high-frequency resonant frequency. 6. The antenna as claimed in claim 1, wherein the antenna further comprises a third radiating part, a first end of the third radiating part being connected to a first end of the second radiator, and the third radiating part and the capacitor structure generating a second high-frequency resonant frequency. 7. The antenna as claimed in claim 1, wherein the antenna further comprises a fourth radiating part, a first end of the fourth radiating part being connected to a first end of the second radiator, and the fourth radiating part and the capacitor structure generating a low-frequency resonant frequency and a high-order resonant frequency. 8. The antenna as claimed in claim 1, wherein the first resonant frequency is a low-frequency resonant frequency. 9. The antenna as claimed in claim 8, wherein the low-frequency resonant frequency is 800MHz. 10. The antenna as claimed in claim 1, wherein the shape of the second radiator includes any one of the following: L-shaped, C-shaped, M-shaped, S-shaped, W-shaped, and N-shaped. 11. The antenna as claimed in claim 1, wherein the first radiating part, the matching circuit and the grounding part are disposed in the same plane of the circuit board. 12. The antenna as claimed in claim 1, wherein the first radiator and the second radiator are formed on a support, wherein the support is made of an insulating material. 13. A mobile terminal, characterized in that it comprises an antenna, a radio frequency processing unit, and a baseband processing unit, wherein, The antenna includes a first radiating section, a matching circuit, and a power supply. The first radiating section includes a first radiator, a second radiator, and a capacitor structure. A first end of the first radiator is connected to the power supply through the matching circuit, and the power supply is connected to a ground. A second end of the first radiator is connected to the first end of the second radiator through the capacitor structure, and the second end of the second radiator is connected to the ground. The first radiating section is used to generate a first resonant frequency. The length of the second radiator is one-eighth of the wavelength corresponding to the first resonant frequency. The signal flow path passes through the capacitor structure and then through a parallel distributed inductor to the ground, forming a left-handed transmission structure. The first end and the second end of the second radiator constitute the parallel distributed inductor in the left-handed transmission structure. The first resonant frequency can be adjusted by changing the length of the distributed inductor between the first end and the second end of the second radiator or by changing the value of the capacitor structure. The baseband processing unit is connected to the power supply through the radio frequency processing unit; The antenna is used to transmit the received wireless signal to the radio frequency processing unit, or to convert the transmitted signal of the radio frequency processing unit into electromagnetic waves and send them out; the radio frequency processing unit is used to perform frequency selection, amplification, and down-conversion processing on the wireless signal received by the antenna, and convert it into an intermediate frequency signal or a baseband signal and send it to the baseband processing unit, or to perform up-conversion and amplification on the baseband signal or intermediate frequency signal sent by the baseband processing unit and send it out through the antenna; the baseband processing unit processes the received intermediate frequency signal or the baseband signal. 14. The mobile terminal as claimed in claim 13, wherein the first end of the second radiator and the second end of the first radiator are close to each other and maintain a distance, forming the capacitor structure. 15. The mobile terminal as described in claim 13, wherein the capacitor structure is a capacitor, and the second end of the first radiator is connected to the first end of the second radiator through the capacitor structure, specifically: the second end of the first radiator is connected to the first end of the second radiator through the capacitor. 16. The mobile terminal as claimed in claim 13, wherein the capacitor structure includes a first branch structure and a second branch structure, the first branch structure includes at least a pair of parallel first branches, the second branch structure includes at least one second branch, the first branches have a gap between them, and the second branch is located between the two first branches and has a gap with the first branches. 17. The mobile terminal as described in any one of claims 13-16, wherein the antenna further comprises a second radiating part, a first end of the second radiating part is connected to a second end of the first radiator, and the second radiating part and the capacitor structure generate a first high-frequency resonant frequency. 18. The mobile terminal as claimed in claim 13, wherein the antenna further includes a third radiating part, a first end of the third radiating part is connected to a first end of the second radiator, and the third radiating part and the capacitor structure generate a second high-frequency resonant frequency. 19. The mobile terminal as claimed in claim 13, wherein the antenna further includes a fourth radiating part, a first end of the fourth radiating part is connected to a first end of the second radiator, and the fourth radiating part and the capacitor structure generate a low-frequency resonant frequency and a high-order resonant frequency. 20. The mobile terminal as claimed in claim 13, wherein the first radiator and the second radiator are metal sheets. 21. The mobile terminal as described in claim 13, wherein the first resonant frequency is a low-frequency resonant frequency. 22. The mobile terminal as described in claim 21, wherein the low-frequency resonant frequency is 800MHz. 23. The mobile terminal as claimed in claim 13, wherein the shape of the second radiator includes any one of the following: L-shaped, C-shaped, M-shaped, S-shaped, W-shaped, and N-shaped. 24. The mobile terminal as claimed in claim 13, wherein the first radiating part, the matching circuit and the grounding part are disposed in the same plane of the circuit board. 25. The mobile terminal as claimed in claim 13, wherein the first radiator and the second radiator are formed on a support, wherein the support is made of an insulating material.