Patent Description:
With the development of mobile communications technologies, a terminal notebook computer is required to support more and more frequency bands, and a MIMO (Multiple-Input Multiple-Output) antenna is more and more widely applied to terminal notebook computers. Referring to <FIG> that shows an antenna structure designed for a conventional notebook computer, the antenna structure includes two IFA antenna units that are adjacent to each other at an interval. A left IFA antenna unit has a first feed point <NUM>. A right IFA antenna unit has a second feed point <NUM>. When the first feed point <NUM> is excited, a current is coupled to the second feed point <NUM> through an antenna floor <NUM>. As a result, an isolation between the two IFA antenna units is decreased.

To resolve the problem that the isolation between the two IFA antenna units is low, a T-shaped decoupling structure <NUM> is added between the two IFA antenna units, as shown in <FIG>. Then, the first feed point <NUM> is excited. In this way, part of a current flowing from the first feed point <NUM> is coupled to the T-shaped decoupling structure <NUM> through the antenna floor <NUM>, thereby reducing an amount of the current flowing to the second feed point <NUM>, and increasing an isolation between the two IFA antenna units. However, the T-shaped decoupling structure <NUM> in <FIG> implements decoupling for a target decoupling frequency band mainly by adjusting a length of a decoupling stub. Generally, a smallest length of the decoupling stub is a quarter of a wavelength corresponding to the target decoupling frequency band. For example, operating frequency bands of the IFA antenna units are <NUM> and <NUM>, respectively. The T-shaped decoupling structure <NUM> includes two decoupling stubs of different lengths, to implement decoupling for the two frequency bands: <NUM> and <NUM>. The longer decoupling stub is configured to implement decoupling for the <NUM> frequency band; and the shorter decoupling stub is configured to implement decoupling for the <NUM> frequency band. As a result, a total length d2 of decoupling stubs of the T-shaped decoupling structure <NUM> for decoupling a <NUM> and <NUM> dual-band antenna needs to reach at least <NUM>, and a total length d of the antenna needs to reach at least <NUM>.

However, as shown in <FIG>, space reserved for an antenna becomes increasingly smaller due to a development trend towards greatly increasing a screen-to-body ratio of a terminal notebook computer product. It is hard for the foregoing large-size antenna to meet a requirement for a small-size antenna in a future terminal product having a greater screen-to-body ratio. Especially, during design of a MIMO multi-band antenna, when two antennas operate at a same frequency and are disposed adjacent to each other, an isolation between the two antennas is greatly decreased. Therefore, how to miniaturize an antenna while increasing an isolation between two antennas becomes a technical challenge to be met by an antenna designer. <CIT> discloses an antenna system with high isolation characteristics.

The present invention provides an antenna decoupling structure according to independent claim <NUM>. The dependent claims set out preferred embodiments. This application provides an antenna decoupling structure, an antenna, and a terminal, to implement decoupling for a target decoupling frequency band by using a constituted LC resonant structure, implement antenna miniaturization, and increase an isolation between antennas.

According to a first aspect, this application provides an antenna decoupling structure. The antenna decoupling structure includes a grounding stub and a capacitor structure, where a first end of the grounding stub is connected to an antenna floor, to form an equivalent inductor; and a first end of the capacitor structure is connected to the antenna floor, and a second end of the capacitor structure is connected to a second end of the grounding stub, so that the equivalent inductor and the capacitor structure form an LC resonant structure, where a parameter corresponding to the LC resonant structure meets a decoupling requirement for a first target decoupling frequency band.

In this way, a capacitance of the capacitor structure and an inductance of the equivalent inductor L are adjusted to ensure that a resonant frequency of the LC resonant structure is the same as the target decoupling frequency band, thereby implementing decoupling for the target decoupling frequency band. Because the resonant frequency depends on the inductance and the capacitance that correspond to the LC resonant structure, antenna miniaturization can be realized by reducing a size of each portion of the decoupling structure. Different resonant modes can be formed by adjusting the parameter corresponding to the LC resonant structure, thereby meeting decoupling requirements for different target decoupling frequency bands.

The antenna decoupling structure provided in this application further includes a first decoupling stub and a second decoupling stub, where the first decoupling stub and the second decoupling stub are respectively disposed on two sides of the grounding stub; a first end of the first decoupling stub is connected to the second end of the grounding stub, and a length of the first decoupling stub meets a decoupling requirement for a second target decoupling frequency band; and a first end of the second decoupling stub is connected to the second end of the grounding stub, and a length of the second decoupling stub meets a decoupling requirement for a third target decoupling frequency band, where the parameter corresponding to the LC resonant structure meets a decoupling requirement for a first target decoupling frequency band, and the first target decoupling frequency band is a lowest frequency band among the first target decoupling frequency band, the second target decoupling frequency band, and the third target decoupling frequency band.

In this way, decoupling for three frequency bands can be implemented by using the LC resonant structure, the first decoupling stub, and the second decoupling stub, respectively, thereby implementing decoupling for a plurality of operating frequency bands.

Furthermore, the length of the first decoupling stub is a quarter of a wavelength corresponding to a center frequency of the second target decoupling frequency band; the length of the second decoupling stub is a quarter of a wavelength corresponding to a center frequency of the third target decoupling frequency band; and an open end formed after bending of the first decoupling stub is disposed opposite to an open end formed after bending of the second decoupling stub.

In this way, the lengths of the first decoupling stub and the second decoupling stub meet the decoupling requirements for the target decoupling frequency bands; and miniaturization is guaranteed. As the open end formed after bending of the first decoupling stub is disposed opposite to the open end formed after bending of the second decoupling stub, space occupied by the first decoupling stub and the second decoupling stub can be further reduced.

In an implementation, the capacitor structure uses a lumped parameter capacitor.

In this way, convenience is brought for implementing miniaturization of the decoupling structure because a size of the lumped parameter capacitor is small.

In an implementation, the capacitor structure is formed by coupling a capacitive coupling stub to the grounding stub that is disposed opposite to a first end of the capacitive coupling stub at an interval, and a second end of the capacitive coupling stub is connected to the antenna floor.

In this way, structures of the capacitive coupling stub and the grounding stub are coupled to form a required capacitor structure, so that a small quantity of components can be added outside the coupled structure.

In an implementation, a plurality of coupling slots are formed between the first end of the capacitive coupling stub and the first end of the grounding stub.

In this way, the plurality of coupling slots are formed between the first end of the capacitive coupling stub and the first end of the grounding stub, which increases a coupling area, and a capacitance of the capacitor structure.

In an implementation, the grounding stub includes a first grounding sub-stub and a second grounding sub-stub that are disposed in an L-shaped form, a first end of the first grounding sub-stub is perpendicularly connected to the antenna floor, a second end of the first grounding sub-stub is perpendicularly connected to a first end of the second grounding sub-stub, and a first groove is formed in a side, facing the antenna floor, of the second grounding sub-stub; and the capacitive coupling stub includes a first capacitive coupling sub-stub and a second capacitive coupling sub-stub that are disposed in a T-shaped form, a first end of the first capacitive coupling sub-stub is disposed in the first groove and opposite to the first groove at an interval, a second end of the first capacitive coupling sub-stub is perpendicularly connected to the antenna floor, a first end of the second capacitive coupling sub-stub is perpendicularly connected to the first capacitive coupling sub-stub, and the second capacitive coupling sub-stub is disposed opposite to a second end of the second grounding sub-stub at an interval.

In this way, the first groove is formed in the grounding stub, and a structure of the capacitive coupling stub is designed to T-shaped to match the first groove, so that the plurality of coupling slots are formed between the capacitive coupling stub and the grounding stub, which increases a capacitance of the coupling capacitor.

In an implementation, the grounding stub includes a first grounding sub-stub, a second grounding sub-stub, and a third grounding sub-stub, a first end of the first grounding sub-stub is perpendicularly connected to the antenna floor, a second end of the first grounding sub-stub is perpendicularly connected to a first end of the second grounding sub-stub, a second end of the second grounding sub-stub is perpendicularly connected to a first end of the third grounding sub-stub, and a second end of the third grounding sub-stub faces the antenna floor; and the capacitive coupling stub includes a third capacitive coupling sub-stub and a fourth capacitive coupling sub-stub, a first end of the third capacitive coupling sub-stub is perpendicularly connected to the antenna floor, a second end of the third capacitive coupling sub-stub is perpendicularly connected to the fourth capacitive coupling sub-stub, a second groove is formed in a side, away from the antenna floor, of the fourth capacitive coupling sub-stub, and the second end of the third grounding sub-stub is disposed in the second groove and opposite to the second groove at an interval.

In this way, the second groove is formed in the capacitive coupling stub, and the third grounding sub-stub disposed opposite to the second groove at an interval is designed on the grounding stub in a matching manner, so that the plurality of coupling slots are formed between the capacitive coupling stub and the grounding stub, which increases a capacitance of the coupling capacitor.

In an implementation, the first target decoupling frequency band ranges from <NUM> to <NUM>, the second target decoupling frequency band ranges from <NUM> to <NUM>, and the third target decoupling frequency band ranges from <NUM> to <NUM>; the grounding stub includes a first grounding sub-stub, a second grounding sub-stub, and a third grounding sub-stub, a first end of the first grounding sub-stub is perpendicularly connected to the antenna floor, a second end of the first grounding sub-stub is perpendicularly connected to a first end of the second grounding sub-stub, a second end of the second grounding sub-stub is perpendicularly connected to a first end of the third grounding sub-stub, and a second end of the third grounding sub-stub faces the antenna floor; the capacitive coupling stub includes a third capacitive coupling sub-stub and a fourth capacitive coupling sub-stub, a first end of the third capacitive coupling sub-stub is perpendicularly connected to the antenna floor, a second end of the third capacitive coupling sub-stub is perpendicularly connected to the fourth capacitive coupling sub-stub, a second groove is formed in a side, away from the antenna floor, of the fourth capacitive coupling sub-stub, and the second end of the third grounding sub-stub is disposed in the second groove and opposite to the second groove at an interval; a shortest horizontal distance between a first side edge of the first grounding sub-stub and the fourth capacitive coupling sub-stub is <NUM>, a shortest horizontal distance between a second side edge of the first grounding sub-stub and the fourth capacitive coupling sub-stub is <NUM>, a distance between the antenna floor and a first side edge of the second grounding sub-stub is <NUM>, and a distance between the antenna floor and a second side edge of the second grounding sub-stub is <NUM>; the first end of the first decoupling stub and the second end of the second grounding sub-stub are connected to each other and form a first connection point, and the first decoupling stub extends from the first connection point in a direction away from the antenna floor by <NUM>, in a direction parallel to the antenna floor and away from the third capacitive coupling sub-stub by <NUM>, in a direction away from the antenna floor by <NUM>, and in a direction parallel to the antenna floor and close to the third capacitive coupling sub-stub by <NUM>, sequentially; and an open end of the second decoupling stub is disposed opposite to an open end of the first decoupling stub, and the second decoupling stub extends from the open end in a direction away from the first decoupling stub by <NUM>, in a direction close to the antenna floor by <NUM>, in a direction close to the first decoupling stub by <NUM>, and in a direction close to and perpendicular to the antenna floor, sequentially, and is then connected to the first connection point.

In this way, the antenna decoupling structure can be applied to an NR antenna, to implement decoupling for operating frequency bands of the NR antenna.

According to a second aspect, this application provides a MIMO antenna. The MIMO antenna includes a first antenna unit, a second antenna unit, and the antenna decoupling structure according to the first aspect, where the antenna decoupling structure is disposed at a preset location between the first antenna unit and the second antenna unit, and is configured to increase an isolation between the first antenna unit and the second antenna unit.

In this way, different resonant modes can be formed by adjusting the parameter corresponding to the LC resonant structure, thereby implementing decoupling for different operating frequency bands of the first antenna unit and the second antenna unit.

In an implementation, the first antenna unit includes a feed stub, a floor stub, and a first radiation stub, where the floor stub includes a first floor sub-stub and a second floor sub-stub; a first end of the first floor sub-stub is connected to the antenna floor; a second end of the first floor sub-stub is connected to a first end of the second floor sub-stub; a second end of the second floor sub-stub is disposed opposite to the feed stub at an interval, to form a coupling capacitor; the floor stub and the feed stub form a left-handed antenna mode, and a parameter corresponding to the left-handed antenna mode meets a frequency requirement for the first antenna unit at a first operating frequency band; the second end of the second floor sub-stub is connected to the first radiation stub, the first radiation stub and the feed stub form a first monopole antenna mode, and a parameter corresponding to the first monopole antenna mode meets a frequency requirement for the first antenna unit at a second operating frequency band; and the first operating frequency band is less than the second operating frequency band.

In this way, the feed stub, the floor stub, and the first radiation stub constitute the two antenna modes: the left-handed antenna mode and the first monopole antenna mode that can resonate with different frequencies. A resonant frequency of a left-handed antenna depends on an inductance and a capacitance. Compared with a length of an IFA antenna, a monopole antenna, or another antenna that can be as small as a quarter of a wavelength, a length of the left-handed antenna can be as small as one eighth of the wavelength. Therefore, a size of the first antenna unit can be further reduced.

In an implementation, the first antenna unit further includes a second radiation stub, where the second radiation stub and the first radiation stub are respectively disposed on two sides of the floor stub, a first end of the second radiation stub is connected to the first end of the second floor sub-stub, the first radiation stub, the second floor sub-stub, the second radiation stub, and the feed stub form a balanced antenna mode, and a parameter corresponding to the balanced antenna mode meets a frequency requirement for the first antenna unit at a third operating frequency band; the second radiation stub, the second floor sub-stub, and the feed stub form a second monopole antenna mode, and a parameter corresponding to the second monopole antenna mode meets a frequency requirement for the first antenna unit at a fourth operating frequency band; and the first operating frequency band is less than the fourth operating frequency band, the fourth operating frequency band is less than the third operating frequency band, and the third operating frequency band is less than the second operating frequency band.

In this way, the feed stub, the floor stub, the first radiation stub, and the second radiation stub constitute the four antenna modes: the left-handed antenna mode, the first monopole antenna mode, the second monopole antenna mode, and the balanced antenna mode that can resonate with different frequencies, so that the first antenna unit can cover more operating frequency bands.

In an implementation, the floor stub further includes a third floor sub-stub, a first end of the third floor sub-stub is perpendicularly connected to the second end of the second floor sub-stub, a third groove is formed in a side, away from the antenna floor, of the feed stub, and a second end of the third floor sub-stub is disposed in the third groove and opposite to the third groove at an interval; and the second radiation stub includes a horizontal radiation stub and a vertical radiation stub, a first end of the horizontal radiation stub is connected to the first end of the second floor sub-stub, a second end of the horizontal radiation stub is connected to a first end of the vertical radiation stub, and a second end of the vertical radiation stub faces the antenna floor.

In this way, the second radiation stub is bent, so that a horizontal dimension of the antenna unit can be further reduced.

In an implementation, the MIMO antenna is used as a WIFI MIMO tri-band antenna, where operating frequency bands of the WIFI MIMO tri-band antenna are <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>, respectively; a shortest horizontal distance between the first floor sub-stub and the third floor sub-stub is <NUM>, a distance between a first side edge of the second floor sub-stub and the antenna floor is <NUM>, a distance between a second side edge of the second floor sub-stub and the antenna floor is <NUM>, a distance between a first side edge of the first radiation stub and a second side edge of the first radiation stub is <NUM>, a distance between a second end of the first radiation stub and a first side edge of the first floor sub-stub is <NUM>, a distance between the second end of the first radiation stub and the second end of the horizontal radiation stub is <NUM>, a distance between a first side edge of the vertical radiation stub and a first side edge of the horizontal radiation stub is <NUM>, a distance between the first side edge of the vertical radiation stub and a second side edge of the horizontal radiation stub is <NUM>, and a distance between the first side edge of the horizontal radiation stub and the antenna floor is <NUM>; and the third groove is <NUM> wide and <NUM> high, and an opening of the third groove is <NUM> wide.

In this way, the antenna unit can cover the operating frequency bands of the WIFI MIMO tri-band antenna.

In an implementation, the MIMO antenna is used as an NR antenna, where operating frequency bands of the NR antenna are <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>, respectively; the first floor sub-stub extends from the first end of the first floor sub-stub in a direction away from the antenna floor by <NUM> and in a direction parallel to the antenna floor by a first preset distance, sequentially, and is connected to the first end of the second floor sub-stub; a distance between a first side edge and a second side edge of the first radiation stub is <NUM>, a shortest distance between a second end of the first radiation stub and the third groove is <NUM>, a distance between a second end of the first radiation stub and the second end of the horizontal radiation stub is <NUM>, and a distance between a first side edge and a second side edge of the vertical radiation stub is <NUM>; and the third groove is <NUM> wide and <NUM> high.

In this way, the antenna unit can cover the operating frequency bands of the NR antenna.

According to a third aspect, this application provides a terminal, including the MIMO antenna according to the second aspect.

In this way, a development trend towards a greater screen-to-body ratio of a terminal product can be met.

Reference numerals in the accompanying drawings are as follows:.

The technical solutions of the embodiments of the present invention are clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely some rather than all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

For ease of understanding of the technical solutions of this application, the following briefly describes a concept: an isolation of an antenna.

"Isolation" (isolation) is a ratio of a transmit power of an antenna unit to a received power of another antenna unit, where a unit of the ratio may be dB. An isolation of an antenna is used to quantitatively represent a strength of coupling between antenna units. The unit of the isolation may be dB. A logarithm, to a base of <NUM>, of a ratio of a transmit power to a received power, namely, lg, is used to represent a value of the isolation whose counting unit is dB. A greater value of the isolation indicates a smaller degree of interference between two antenna units. A MIMO antenna, having characteristics such as a high channel capacity and high channel reliability, is more and more widely applied to various wireless communications systems. However, antenna units of an antenna are adjacent to each other because accommodating space of the antenna is limited. As a result, an isolation of the antenna is low. Especially, when two antenna units of the antenna are at a same operating frequency band, a coupling function between the antenna units is serious, and an isolation of the antenna is greatly decreased.

To increase the isolation of the antenna, in an implementation, a T-shaped decoupling structure may be added between the two antenna units.

<FIG> that is a schematic structural diagram of an antenna having a T-shaped decoupling structure. The antenna includes two IFA antenna units and the T-shaped decoupling structure <NUM> between the two IFA antenna units. During excitation of a first feed point <NUM>, the T-shaped decoupling structure <NUM> generates a resonant frequency that is the same as operating frequency bands of the IFA antenna units, so that part of a current is coupled to the T-shaped decoupling structure <NUM> through the antenna floor <NUM>, thereby reducing an amount of the current flowing to the second feed point <NUM>, and increasing an isolation between the two IFA antenna units.

Because a length of the IFA antenna unit is related to a frequency, a higher frequency indicates a shorter wavelength and a shorter length of the IFA antenna unit; and a lower frequency indicates a longer wavelength and a longer length of the IFA antenna unit. For example, the IFA antenna unit in <FIG> includes two radiation stubs, to cover two operating frequency bands: <NUM> and <NUM>. A length of the longer radiation stub is a quarter of a wavelength corresponding to <NUM>; and a length of the shorter radiation stub is a quarter of a wavelength corresponding to <NUM>. It can be determined, through calculation, that a total antenna length d1 of the IFA antenna units is <NUM> according to a relationship between a wavelength and a frequency. The T-shaped decoupling structure <NUM> implements decoupling by generating a resonant frequency that is the same as the operating frequency band of the IFA antenna unit. Therefore, the T-shaped decoupling structure <NUM> also includes two decoupling stubs of different lengths, to implement decoupling for the two frequency bands: <NUM> and <NUM>. The longer decoupling stub is configured to implement decoupling for the <NUM> frequency band; and the shorter decoupling stub is configured to implement decoupling for the <NUM> frequency band. Similarly, it can be determined, through calculation, that a total horizontal length d2 of the T-shaped decoupling structure <NUM> is also <NUM>. Therefore, a total horizontal length d of the antenna having the T-shaped decoupling structure <NUM> shown in <FIG> reaches at least <NUM>. However, this dimension of the antenna may not meet a requirement for miniaturization of the antenna.

This application provides a MIMO antenna, to resolve a problem that a dimension of an antenna cannot meet a requirement for miniaturization of the antenna. The following describes a structure of the MIMO antenna in this embodiment of this application with reference to the accompanying drawings.

First, the antenna decoupling structure of the MIMO antenna is described below.

<FIG> is a schematic structural diagram of an antenna decoupling structure according to an example of this application not comprising all the features of the claimed invention, that is however useful for the understanding of the invention. The antenna decoupling structure <NUM> includes a capacitor structure and a grounding stub <NUM> connected to the capacitor structure. A first end of the grounding stub <NUM> is connected to an antenna floor <NUM>, to form an equivalent inductor L. A first end of the capacitor structure is connected to the antenna floor <NUM>, and a second end of the capacitor structure is connected to a second end of the grounding stub <NUM>, so that the equivalent inductor L and the capacitor structure form an LC resonant structure.

In this embodiment of this application, a capacitance of the capacitor structure and an inductance of the equivalent inductor L are adjusted to ensure that a resonant frequency of the LC resonant structure is the same as the target decoupling frequency band, thereby implementing decoupling. The antenna decoupling structure <NUM> in this embodiment of this application mainly includes the capacitor structure and the grounding stub <NUM> that is used for forming the equivalent inductor L. To reduce a size of the antenna decoupling structure <NUM>, that is, shorten a coupling path of a current, it needs to be ensured that a size of the grounding stub <NUM> is as small as possible. Then, the capacitance is adjusted according to a relationship between a resonant frequency, and an inductance and a capacitance, to ensure that the resonant frequency of the LC resonant structure is the same as the target decoupling frequency band. A specific shape and size of the antenna decoupling structure <NUM> in this embodiment of this application may be determined through simulation and experiments according to a decoupling requirement for the target decoupling frequency band.

The capacitor structure is not limited in this example of this application. In an implementation, as shown in <FIG>, a lumped parameter capacitor 31A may be connected in series between the second end of the grounding stub <NUM> and the antenna floor <NUM>. In another implementation, as shown in <FIG>, a capacitive coupling stub 31B is added. A second end of the capacitive coupling stub 31B is connected to the antenna floor <NUM>; and a first end of the capacitive coupling stub 31B is disposed opposite to the second end of the grounding stub <NUM> at an interval. In this way, the first end of the capacitive coupling stub 31B and the second end of the grounding stub <NUM> form a coupling capacitor, as shown in a dashed block in <FIG>. The coupling capacitor is a capacitor structure. The capacitor structure may be a standard capacitor board structure, or a 3D coupling capacitor structure. An area, opposite to the first end of the capacitive coupling stub 31B, of the second end of the grounding stub <NUM> is a coupling area of the coupling capacitor. A distance between the second end of the grounding stub <NUM> and the first end of the capacitive coupling stub 31B is a coupling distance. In this embodiment of this application, it may be considered that a height of a gap between the second end of the grounding stub <NUM> and the first end of the capacitive coupling stub 31B is equivalent to the coupling distance. A capacitance of the coupling capacitor is in direct proportion to the coupling area, but is in inverse proportion to the coupling distance. Therefore, the capacitance can be increased by increasing the coupling area or decreasing the coupling distance. Neither of shapes of the capacitive coupling stub 31B and the grounding stub <NUM> is limited in this embodiment of this application, provided that the capacitive coupling stub 31B and the grounding stub <NUM> are at least partially opposite to each other in an up-down direction.

In an implementation, the capacitor structure may be that shown in <FIG>. The grounding stub <NUM> may include a first grounding sub-stub <NUM> and a second grounding sub-stub <NUM> that are disposed in an L-shaped form, a first end of the first grounding sub-stub <NUM> is perpendicularly connected to the antenna floor <NUM>, a second end of the first grounding sub-stub <NUM> is perpendicularly connected to a first end of the second grounding sub-stub <NUM>, and a first groove <NUM> is formed in a side, facing the antenna floor <NUM>, of the second grounding sub-stub <NUM>. Correspondingly, the capacitive coupling stub 31B includes a first capacitive coupling sub-stub 31B <NUM> and a second capacitive coupling sub-stub 31B2 that are disposed in a T-shaped form, a first end of the first capacitive coupling sub-stub 31B <NUM> is disposed in the first groove <NUM> and opposite to the first groove <NUM> at an interval, a second end of the first capacitive coupling sub-stub 31B <NUM> is perpendicularly connected to the antenna floor <NUM>, a first end of the second capacitive coupling sub-stub 31B2 is perpendicularly connected to the first capacitive coupling sub-stub 31B <NUM>, and the second capacitive coupling sub-stub 31B2 is disposed opposite to a second end of the second grounding sub-stub <NUM> at an interval. In this way, the first groove is formed in the grounding stub <NUM>, and a structure of the capacitive coupling stub 31B is designed to T-shaped to match the first groove, so that a plurality of coupling slots are formed between the capacitive coupling stub 31B and the grounding stub <NUM>, which increases a capacitance of the coupling capacitor.

In another implementation, the capacitor structure may be that shown in <FIG>. A third grounding sub-stub <NUM> is connected to the second end of the second grounding sub-stub <NUM>, a first end of the third grounding sub-stub <NUM> is perpendicularly connected to the second end of the second grounding sub-stub <NUM>, and a second end of the third grounding sub-stub <NUM> faces the antenna floor <NUM>. Correspondingly, the capacitive coupling stub 31B includes a third capacitive coupling sub-stub 31B3 and a fourth capacitive coupling sub-stub 31B4, a first end of the third capacitive coupling sub-stub 31B3 is perpendicularly connected to the antenna floor <NUM>, a second end of the third capacitive coupling sub-stub 31B3 is perpendicularly connected to the fourth capacitive coupling sub-stub 31B4, a second groove 31B5 is formed in a side, away from the antenna floor <NUM>, of the fourth capacitive coupling sub-stub 31B4, and the second end of the third grounding sub-stub <NUM> is disposed in the second groove 31B5 and opposite to the second groove 31B5 at an interval. In this way, the second groove is formed in the capacitive coupling stub, and the third grounding sub-stub disposed opposite to the second groove at an interval is designed on the grounding stub in a matching manner, so that the plurality of coupling slots are formed between the capacitive coupling stub 31B and the grounding stub <NUM>, which increases a capacitance of the coupling capacitor.

Because a resonant frequency of the antenna decoupling structure provided in this embodiment of this application depends on the inductance and the capacitance that correspond to the LC resonant structure, antenna miniaturization can be realized by reducing a size of each portion of the decoupling structure.

Decoupling for two frequency bands <NUM> and <NUM> is used as an example. A horizontal length d2 of the antenna decoupling structure <NUM> in <FIG> is <NUM>, and is <NUM> shorter than that of the T-shaped decoupling structure. Therefore, a requirement for miniaturization of an antenna can be met by applying, to the antenna, the antenna decoupling structure provided in this embodiment of this application.

<FIG> is a schematic structural diagram of a MIMO antenna according to an example of this application not comprising all the features of the claimed invention, that is however useful for the understanding of the invention. The MIMO antenna includes a first antenna unit <NUM>, a second antenna unit <NUM>, and the antenna decoupling structure <NUM> according to the foregoing embodiment. The antenna decoupling structure <NUM> is disposed at a preset location between the first antenna unit <NUM> and the second antenna unit <NUM>.

Structures of the first antenna unit <NUM> and the second antenna unit <NUM> are not limited in this embodiment of this application. For example, the first antenna unit <NUM> may be an IFA antenna, a PIFA antenna, a left-handed antenna, or the like; and a structure of the second antenna unit <NUM> may be the same as or different from that of the first antenna unit <NUM>.

Operating frequency bands of the first antenna unit <NUM> and the second antenna unit <NUM> are not limited in this application. The first antenna unit <NUM> and the second antenna unit <NUM> may have at least one same operating frequency band. For example, if operating frequency bands of the first antenna unit <NUM> are <NUM> and <NUM>, and operating frequency bands of the second antenna unit <NUM> are <NUM> and <NUM>, the first antenna unit <NUM> and the second antenna unit <NUM> have one same operating frequency band: <NUM>. For another example, if operating frequency bands of the first antenna unit <NUM> are <NUM> and <NUM>, and operating frequency bands of the second antenna unit <NUM> are <NUM> and <NUM>, the first antenna unit <NUM> and the second antenna unit <NUM> have two same operating frequency bands: <NUM> and <NUM>, that are two common operating frequency bands of existing WIFI antennas.

A target decoupling frequency band of the antenna decoupling structure <NUM> is not limited in this embodiment of this application. For example, the antenna decoupling structure <NUM> may be configured to implement decoupling for any one or two of frequency bands: <NUM>, <NUM>, and <NUM>. In other words, the antenna decoupling structure <NUM> in this embodiment of this application can decouple a single-band antenna or a dual-band antenna. If the antenna decoupling structure <NUM> is configured to decouple a single-band antenna, that is, the first antenna unit <NUM> and the second antenna unit <NUM> have a same operating frequency band, parameters corresponding to the antenna decoupling structure <NUM> (these parameters include a shape and a size of the grounding stub, a capacitance of the capacitor structure, and the like) can resonate with a frequency that is the same as the target decoupling frequency band. If the antenna decoupling structure <NUM> is configured to decouple a dual-band antenna, that is, the first antenna unit <NUM> and the second antenna unit <NUM> have two same operating frequency bands, the parameters corresponding to the antenna decoupling structure <NUM> can form two resonant modes. The two resonant modes can respectively resonate with frequencies that are the same as the two target decoupling frequency bands.

The following further describes the MIMO antenna having the antenna decoupling structure <NUM> capable of decoupling two frequency bands: <NUM> and <NUM>.

As shown in <FIG>, the first antenna unit <NUM> and the second antenna unit <NUM> have two same operating frequency bands: <NUM> and <NUM>. The antenna decoupling structure <NUM> may be determined through simulation and experiments, to implement decoupling for two frequency bands: <NUM> and <NUM>, so that under an excitation condition of the <NUM> frequency band, a left-handed mode in the antenna decoupling structure <NUM> is a strongest resonant mode, as a current mode shown in <FIG>; and under an excitation condition of the <NUM> frequency band, a loop mode in the antenna decoupling structure <NUM> is a strongest resonant mode, as a current mode shown in <FIG>. The excitation condition of the <NUM> frequency band is used as an example. During excitation of a first feed point <NUM>, a current flowing through the antenna floor <NUM> indirectly excites the antenna decoupling structure <NUM>, and the current mode shown in <FIG> is formed in the antenna decoupling structure <NUM>, so that the LC resonant structure can generate a <NUM> resonant frequency. Therefore, the current flowing through the antenna floor <NUM> is coupled to the LC resonant structure, which reduces a current flowing to a second feed point <NUM>, and increases an isolation between the first antenna unit and the second antenna unit. The first feed point <NUM> is a feed point of the first antenna unit <NUM>. The second feed point <NUM> is a feed point of the second antenna unit <NUM>.

In this example of this application, the antenna decoupling structure <NUM> capable of decoupling a <NUM> and <NUM> dual-band antenna is determined through simulation and experiments. As shown in <FIG>, a horizontal length d2 is <NUM>. It can be determined, through calculation, that lengths d1 of the first antenna unit and the second antenna unit are both <NUM> according to a relational expression between a wavelength and a frequency. A total horizontal length d of the MIMO antenna is <NUM>. Compared with the MIMO antenna in <FIG>, the MIMO antenna in <FIG> has a smaller size, thereby meeting a requirement for miniaturization of the antenna.

Still referring to <FIG>, <FIG>, and <FIG>, <FIG> shows a performance curve of the first antenna unit <NUM> in <FIG> in a simulation experiment; <FIG> shows a performance curve of the second antenna unit <NUM> in <FIG> in a simulation experiment; and <FIG> shows isolation curves of the MIMO antenna in <FIG> and the MIMO antenna in <FIG> in a simulation experiment. Each of the performance curves of the first antenna unit <NUM> and the second antenna unit <NUM> includes a return loss, radiation efficiency, and system efficiency. Both units of the radiation efficiency and the system efficiency may be dB. If values of the radiation efficiency and the system efficiency are represented by using a counting unit dB, a value closer to <NUM> dB indicates that the radiation efficiency and the system efficiency are closer to <NUM>%. It can be learned, from curves of return losses in <FIG> and <FIG>, that the first antenna unit <NUM> and the second antenna unit <NUM> have two same operating frequency bands: <NUM> and <NUM>. It can be learned, from <FIG>, that both the radiation efficiency and the system efficiency of the first antenna unit <NUM> at the two operating frequency bands of <NUM> and <NUM> are close to <NUM>%. It can be learned, from <FIG>, that both the radiation efficiency and the system efficiency of the second antenna unit <NUM> at the two operating frequency bands of <NUM> and <NUM> are close to <NUM>%. It can be learned, from <FIG>, that after the antenna decoupling structure <NUM> in this embodiment of this application is added, both isolations at the frequency bands of <NUM> and <NUM> are increased by about 5dB, so that the isolations at the frequency bands of <NUM> and <NUM> are about -<NUM> dB and -<NUM> dB, respectively, thereby completely meeting an isolation requirement.

In summary, all of the radiation efficiency, the system efficiency, and the isolation of the MIMO antenna provided in the foregoing embodiment of this application are satisfactory. In addition, the horizontal dimension d2 of the antenna decoupling structure <NUM> is <NUM> shorter than that of the T-shaped decoupling structure <NUM>.

An embodiment of this application further provides a structure of an antenna unit. The structure of the antenna unit may be the first antenna unit in the foregoing embodiment.

<FIG> is a schematic structural diagram of another MIMO antenna according to an example of this application not comprising all the features of the claimed invention, that is however useful for the understanding of the invention. In a first antenna unit <NUM> in this MIMO antenna, a feed stub <NUM>, a floor stub <NUM>, and a first radiation stub <NUM> constitute two antenna modes: a left-handed antenna mode and a first monopole antenna mode that can resonate with different frequencies. A structure of the second antenna unit <NUM> may be the same as or different from that of the first antenna unit <NUM>. This is not limited in this application.

As shown in <FIG>, the left-handed antenna mode of the first antenna unit <NUM> includes the feed stub <NUM> and the floor stub <NUM>. The floor stub <NUM> includes a first floor sub-stub <NUM> and a second floor sub-stub <NUM>. A first end of the first floor sub-stub <NUM> is connected to the antenna floor <NUM>. A second end of the first floor sub-stub <NUM> is connected to a first end of the second floor sub-stub <NUM>. A second end of the second floor sub-stub <NUM> is disposed opposite to the feed stub <NUM> at an interval, to form a coupling capacitor. In this way, the floor stub <NUM> and the feed stub <NUM> form a left-handed antenna mode, and a parameter corresponding to the left-handed antenna mode meets a frequency requirement for the first antenna unit at a first operating frequency band. The first operating frequency band may be any one of the following frequency bands: <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and the like. This is not limited in this embodiment of this application.

It can be ensured, by adjusting shapes and sizes of the floor stub <NUM> and the feed stub <NUM> and performing determining with reference to simulation and experiments, that the parameter corresponding to the left-handed antenna mode meets a communications requirement for the first antenna unit at the first operating frequency band. For details about the left-handed antenna mode, refer to description of the LC resonant structure in the foregoing embodiment. In the left-handed antenna mode, a feed point is connected to a capacitor in series and then connected to a radiator for radiation. Owing to existence of a distributed capacitor, a resonant frequency of the left-handed antenna mode depends on an equivalent inductance and capacitance of the composite structure, so that the left-handed antenna mode has a small size. A difference between the left-handed antenna mode and the LC resonant structure lies in that resonance of the left-handed antenna mode is directly excited by the first feed point <NUM> of the first antenna unit <NUM>, but resonance of the LC resonant structure is indirectly excited by exciting a current generated by the first feed point <NUM> to flow through the antenna floor. A structure of the coupling capacitor formed in the left-handed antenna mode is not limited in this application. For details, refer to the capacitor structure of the LC resonant structure in the foregoing embodiment.

A resonant frequency of a left-handed antenna depends on an inductance and a capacitance. Compared with a length of an IFA antenna, a monopole antenna, or another antenna that can be as small as a quarter of a wavelength, a length of the left-handed antenna can be as small as one eighth of the wavelength. Therefore, a size of the first antenna unit <NUM> can be further reduced. The first monopole antenna mode of the first antenna unit <NUM> includes the feed stub <NUM> and the first radiation stub <NUM>. The second end of the second floor sub-stub <NUM> is connected to the first radiation stub <NUM>, the first radiation stub <NUM> and the feed stub <NUM> form a first monopole antenna mode, and a parameter corresponding to the first monopole antenna mode meets a frequency requirement for the first antenna unit <NUM> at a second operating frequency band. The second operating frequency band may be different from the first operating frequency band, and may be any one of the following operating frequency bands: <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and the like. This is not limited in this embodiment of this application.

Transmit-to-received conversion efficiency of the antenna is highest when the length of the antenna is a quarter of a wavelength of a radio signal. Therefore, a best length of the first radiation stub <NUM> in the first monopole antenna mode can be obtained by calculating a wavelength based on a center transmit frequency and a center received frequency, namely, a center frequency of the second operating frequency band of the first antenna unit and dividing the wavelength by <NUM>. For example, if the center frequency of the second operating frequency band is <NUM>, a wavelength λ corresponding to <NUM> can be calculated according to a relational expression v=fλ between a frequency f and the wavelength λ. Further, it can be calculated that a length of the first radiation stub <NUM> is λ/<NUM>.

It can be learned that a lower frequency corresponds to a greater length of the first radiation stub <NUM>. Therefore, to reduce the size of the first antenna unit <NUM>, the left-handed antenna in the first antenna unit <NUM> should be configured to resonant with a low frequency, and the first monopole antenna mode should be configured to resonant with a low frequency.

For example, the first operating frequency band is <NUM>, and the second operating frequency band is <NUM>. As shown in <FIG>, in the MIMO antenna, horizontal lengths d1 of the first antenna unit and the second antenna unit are both <NUM>; a horizontal length d2 of the antenna decoupling structure <NUM> is <NUM>; and a total horizontal length d of the antenna is <NUM> that is <NUM> shorter than the total horizontal length of the antenna in <FIG>.

In this way, the antenna unit can cover more operating frequency bands. An embodiment of this application provides another structure of an antenna unit. The structure of the antenna unit may be the first antenna unit in the foregoing embodiment.

<FIG> is a schematic structural diagram of still another MIMO antenna according to an example of this application not comprising all the features of the claimed invention, that is however useful for the understanding of the invention. <FIG> shows still another structure of the first antenna unit. The structure of the first antenna unit in <FIG> is substantially the same as the structure of the first antenna unit in <FIG>; and a difference between the two structures is that the first antenna unit <NUM> in <FIG> is additionally provided with a second radiation stub <NUM>. The second radiation stub <NUM> and the first radiation stub <NUM> are respectively disposed on two sides of the floor stub <NUM>. A first end of the second radiation stub <NUM> is connected to the first end of the second floor sub-stub <NUM>.

The feed stub <NUM>, the floor stub <NUM>, the first radiation stub <NUM>, and the second radiation stub <NUM> of the first antenna unit <NUM> in <FIG> constitute four antenna modes: a left-handed antenna mode, a first monopole antenna mode, a second monopole antenna mode, and a balanced antenna mode that can resonate with different frequencies, so that the first antenna unit <NUM> can cover more operating frequency bands.

As shown in <FIG>, the left-handed antenna mode and the first monopole antenna mode in this embodiment of this application are the same as those in the foregoing embodiment.

The first radiation stub <NUM>, the second floor sub-stub <NUM>, the second radiation stub <NUM>, and the feed stub <NUM> form the balanced antenna mode. A parameter corresponding to the balanced antenna mode meets a frequency requirement for the first antenna unit <NUM> at a third operating frequency band. The third operating frequency band may be any one of the following frequency bands: <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and the like. This is not limited in this embodiment of this application.

The second radiation stub <NUM>, the second floor sub-stub <NUM>, and the feed stub <NUM> form the second monopole antenna mode. The second radiation stub <NUM> may be bent to reduce horizontal space occupied by the second radiation stub <NUM>. For example, as shown in <FIG>, the second radiation stub <NUM> is divided into a horizontal radiation stub <NUM> and a vertical radiation stub <NUM> that are perpendicularly connected to each other; a first end of the horizontal radiation stub <NUM> is connected to the first end of the second floor sub-stub <NUM>; a second end of the horizontal radiation stub <NUM> is connected to a first end of the vertical radiation stub <NUM>; and a second end of the vertical radiation stub <NUM> faces the antenna floor <NUM>. A parameter corresponding to the second monopole antenna mode meets a frequency requirement for the first antenna unit at a fourth operating frequency band. The fourth operating frequency band may be any one of the following frequency bands: <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and the like. This is not limited in this embodiment of this application.

A length of the first radiation stub <NUM> may be a quarter of a wavelength corresponding to a center frequency of the second operating frequency band. A total length of the second radiation stub and the second floor sub-stub <NUM> may be a quarter of a wavelength corresponding to the fourth operating frequency band. A total length of the first radiation stub <NUM>, the second floor sub-stub <NUM>, and the second radiation stub <NUM> may be a half of a wavelength corresponding to the third operating frequency band. To implement size minimization of the first antenna unit <NUM>, the first operating frequency band is less than the fourth operating frequency band, the fourth operating frequency band is less than the third operating frequency band, and the third operating frequency band is less than the second operating frequency band. For example, the first operating frequency band is <NUM>, the second operating frequency band is <NUM>, the third operating frequency band is <NUM>, and the fourth operating frequency band is <NUM>.

In summary, the first antenna unit provided in the foregoing embodiment of this application can cover a plurality of operating frequency bands by constituting a plurality of antenna modes. Therefore, the foregoing antenna unit can be applied to a WIFI MIMO tri-band antenna or an NR antenna. Operating frequency bands of the WIFI MIMO tri-band antenna are <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>, respectively. Operating frequency bands of the NR antenna are <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>, respectively.

The following describes scenarios in which the foregoing first antenna unit is applied to the WIFI MIMO tri-band antenna and the NR antenna, respectively.

The scenario in which the foregoing first antenna unit is applied to the WIFI MIMO tri-band antenna is shown in <FIG>. Horizontal lengths d1 of the first antenna unit and the second antenna unit are both <NUM>. A horizontal length d2 of the antenna decoupling structure <NUM> is <NUM>. A total horizontal length d of the MIMO antenna is <NUM> that is <NUM> shorter than the total horizontal length of the MIMO antenna in <FIG>. Still referring to <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>, <FIG> is a schematic diagram of a current mode of the first antenna unit in <FIG> at the <NUM> frequency band; <FIG> is a schematic diagram of a current mode of the first antenna unit in <FIG> at the <NUM> frequency band; <FIG> is a schematic diagram of a current mode of the first antenna unit in <FIG> at the <NUM> frequency band; <FIG> is a schematic diagram of a current mode of the first antenna unit in <FIG> at the <NUM> frequency band; <FIG> is a diagram of a performance curve of a decoupling structure-free antenna in <FIG>; <FIG> is a diagram of a performance curve of an antenna that includes a decoupling structure and that is in <FIG>; and <FIG> is a diagram of comparison between isolation curves of the antenna in <FIG> and a decoupling structure-free antenna in <FIG>. In <FIG> and <FIG>, S1,<NUM> denotes a curve of a return loss of the first antenna unit; S2,<NUM> denotes a curve of a return loss of the second antenna unit; and S2,<NUM> denotes isolation curves of the first antenna unit and the second antenna unit.

It can be learned, from <FIG>, <FIG>, that the first antenna unit provided in the embodiments of this application is in different current modes at different operating frequency bands. As shown in <FIG>, the first antenna unit is in the left-handed antenna mode at the operating frequency band of <NUM>. As shown in <FIG>, the first antenna unit is in the second monopole antenna mode at the operating frequency band of <NUM>. As shown in <FIG>, the first antenna unit is in the balanced antenna mode at the operating frequency band of <NUM>. As shown in <FIG>, the first antenna unit is in the first monopole antenna mode at the operating frequency band of <NUM>.

It can be learned, from curves of return losses in <FIG> and <FIG>, that a MIMO antenna using the first antenna unit provided in this application can cover the operating frequency bands of the WIFI MIMO tri-band antenna: <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>. It can be learned, from <FIG>, that after using the antenna decoupling structure <NUM> provided in this embodiment of this application, isolations of the antenna in <FIG> at the operating frequency bands: <NUM>, <NUM>, <NUM>, and <NUM> are all increased, and are all less than -<NUM> dB, thereby completely meeting an isolation requirement.

<FIG> shows a size of the foregoing first antenna unit when the first antenna unit is applied to the WIFI MIMO tri-band antenna. The floor stub <NUM> includes a first floor sub-stub <NUM>, a second floor sub-stub <NUM>, and a third floor sub-stub <NUM>. A first end of the third floor sub-stub <NUM> is perpendicularly connected to the second end of the second floor sub-stub <NUM>, a third groove <NUM> is formed in a side, away from the antenna floor <NUM>, of the feed stub <NUM>, and a second end of the third floor sub-stub <NUM> is disposed in the third groove <NUM> and opposite to the third groove <NUM> at an interval to form the coupling capacitor. The second radiation stub <NUM> includes a horizontal radiation stub <NUM> and a vertical radiation stub <NUM> that are perpendicularly connected to each other; a first end of the horizontal radiation stub <NUM> is connected to the first end of the second floor sub-stub <NUM>; a second end of the horizontal radiation stub <NUM> is connected to a first end of the vertical radiation stub <NUM>; and a second end of the vertical radiation stub <NUM> faces the antenna floor <NUM>. A shortest horizontal distance a<NUM> between the first floor sub-stub <NUM> and the third floor sub-stub <NUM> is <NUM>. A distance a<NUM> between a first side edge of the second floor sub-stub <NUM> and the antenna floor <NUM> is <NUM>. A distance as between a second side edge of the second floor sub-stub <NUM> and the antenna floor <NUM> is <NUM>. The first side edge of the second floor sub-stub <NUM> is a side edge parallel to and close to the antenna floor. The second side edge of the second floor sub-stub <NUM> is a side edge parallel to and away from the antenna floor. A distance a<NUM> between a first side edge of the first radiation stub <NUM> and a second side edge of the first radiation stub <NUM> is <NUM>. A distance as between a second end of the first radiation stub <NUM> and a first side edge of the first floor sub-stub <NUM> is <NUM>. The first side edge of the first radiation stub <NUM> is a side edge parallel to and close to the antenna floor. The second side edge of the first radiation stub <NUM> is a side edge parallel to and away from the antenna floor. The first side edge of the first floor sub-stub <NUM> is a side edge perpendicular to the antenna floor and close to the feed stub <NUM>. A distance a<NUM> between the second end of the first radiation stub <NUM> and the second end of the horizontal radiation stub <NUM> is <NUM>. A distance a<NUM> between a first side edge of the vertical radiation stub <NUM> and a first side edge of the horizontal radiation stub <NUM> is <NUM>. A distance as between the first side edge of the vertical radiation stub <NUM> and a second side edge distance of the horizontal radiation stub <NUM> is <NUM>. A distance a<NUM> between the first side edge of the horizontal radiation stub <NUM> and the antenna floor <NUM> is <NUM>. A shortest horizontal distance a<NUM> between the vertical radiation stub <NUM> and the second floor sub-stub <NUM> is <NUM>. The first side edge of the vertical radiation stub <NUM> is a side edge parallel to and close to the antenna floor. The first side edge of the horizontal radiation stub <NUM> is a side edge parallel to and close to the antenna floor. The second side edge of the horizontal radiation stub <NUM> is a side edge parallel to and away from the antenna floor. A width a<NUM> of the third groove <NUM> is <NUM>. A height a<NUM> of the third groove <NUM> is <NUM>. A width a<NUM> of an opening of the third groove <NUM> is <NUM>. The opening of the third groove is at a center location in a width direction of the third groove <NUM>.

Another antenna decoupling structure is described before the scenario in which the foregoing antenna unit is applied to the NR antenna. The antenna decoupling structure <NUM> can decouple more operating frequency bands, thereby matching the foregoing antenna unit and being applied to the NR antenna.

<FIG> is a schematic structural diagram of an antenna decoupling structure <NUM> according to an embodiment of this application.

The antenna decoupling structure <NUM> provided in this embodiment of this application is substantially the same as the antenna decoupling structure <NUM> provided in the foregoing embodiments. A difference between the two structures is that the antenna decoupling structure <NUM> provided in this embodiment of this application is additionally provided with a first decoupling stub <NUM> and a second decoupling stub <NUM>.

As shown in <FIG>, the antenna decoupling structure <NUM> provided in this embodiment of this application includes an LC resonant structure, the first decoupling stub <NUM>, and the second decoupling stub <NUM>. A capacitor structure in the LC resonant structure in this embodiment of this application may be formed by coupling a capacitive coupling stub 31B and a grounding stub <NUM> disposed opposite to the capacitive coupling stub 31B at an interval, as shown in <FIG>; or may use a lumped parameter capacitor 31A, as shown in <FIG>. For details about the LC resonant structure in this embodiment of this application, refer to description of the LC resonant structure in the foregoing embodiments. A first end of the first decoupling stub <NUM> is connected to the second end of the grounding stub <NUM>. A first end of the second decoupling stub <NUM> is connected to the second end of the grounding stub <NUM>. The first decoupling stub <NUM> and the second decoupling stub <NUM> are respectively disposed on two sides of the grounding stub <NUM>. A parameter corresponding to the LC resonant structure can meet the decoupling requirement for a first target decoupling frequency band. A length of the first decoupling stub <NUM> can meet the decoupling requirement for a second target decoupling frequency band. A length of the second decoupling stub <NUM> can meet the decoupling requirement for a third target decoupling frequency band. Shapes and sizes of the first decoupling stub <NUM> and the second decoupling stub <NUM> are not limited in this application. For example, the length of the first decoupling stub <NUM> may be a quarter of a wavelength corresponding to a center frequency of the second target decoupling frequency band; and the length of the second decoupling stub <NUM> may be a quarter of a wavelength corresponding to a center frequency of the third target decoupling frequency band. An open end formed after bending of the first decoupling stub <NUM> may be disposed opposite to an open end formed after bending of the second decoupling stub <NUM>, thereby reducing space occupied by the first decoupling stub <NUM> and the second decoupling stub <NUM>.

According to the antenna decoupling structure <NUM> in <FIG> or <FIG>, decoupling for three frequency bands can be implemented by using the LC resonant structure, the first decoupling stub <NUM>, and the second decoupling stub <NUM>, respectively, thereby implementing decoupling for these operating frequency bands. The LC resonant structure may be configured to implement decoupling for the lowest frequency band among the three target decoupling frequency bands, thereby obtaining a smallest size of the antenna decoupling structure <NUM>.

The antenna decoupling structure <NUM> in <FIG> or <FIG> may be configured to decouple a WIFI MIMO tri-band antenna having three same operating frequency bands, or an NR antenna using <NUM> (5th generation mobile networks). Operating frequency bands of the WIFI MIMO tri-band antenna are <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>, respectively. Operating frequency bands of the NR antenna are <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>, respectively.

It should be understood that the antenna decoupling structure <NUM> in <FIG> or <FIG> may be used with the first antenna unit <NUM> and the second antenna unit <NUM> in <FIG> or <FIG>, or used with an antenna of another type. This is not limited in this application.

For example, the foregoing antenna decoupling structure and antenna unit are jointly applied to the NR antenna, that is, the first target decoupling frequency band is <NUM>, the second target decoupling frequency band is <NUM>, and the third target decoupling frequency band is <NUM>. As shown in <FIG>, a horizontal length d2 of the antenna decoupling structure <NUM> is <NUM>, and is <NUM> shorter than that of an existing T-shaped decoupling structure.

<FIG> is a schematic structural diagram of yet another MIMO antenna according to an embodiment of this application. The antenna includes a first antenna unit <NUM>, a second antenna unit <NUM>, and an antenna decoupling structure <NUM>. The first antenna unit <NUM> uses the first antenna unit <NUM> shown in <FIG>. The antenna decoupling structure <NUM> uses the antenna decoupling structure <NUM> in <FIG> or <FIG>. A structure of the second antenna unit may be the same as that of the first antenna unit.

For example, the foregoing antenna decoupling structure and antenna unit are jointly applied to the NR antenna. According to the MIMO antenna in <FIG>, horizontal lengths d1 of the first antenna unit <NUM> and the second antenna unit <NUM> are both <NUM>; a horizontal length d2 of the antenna decoupling structure <NUM> is <NUM>; and a total horizontal length d of the MIMO antenna is <NUM> that is <NUM> shorter than the total horizontal length of the MIMO antenna in <FIG>.

Still referring to <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>, <FIG> are schematic diagrams of current distribution of an antenna decoupling structure <NUM>-free MIMO antenna when a first feed point is excited under excitation conditions of frequency bands: <NUM>, <NUM>, and <NUM>, respectively; <FIG> are schematic diagrams of current distribution of the MIMO antenna in <FIG> when a first feed point is excited under excitation conditions of frequency bands: <NUM>, <NUM>, and <NUM>, respectively; <FIG>, and <FIG> are schematic diagrams of current modes of the antenna decoupling structure <NUM> in <FIG> corresponding to frequency bands: <NUM>, <NUM>, and <NUM>, respectively; <FIG> is a diagram of a performance curve of an antenna decoupling structure-free MIMO antenna (as shown in <FIG>); <FIG> is a diagram of a performance curve of a MIMO antenna (as shown in <FIG>) having an antenna decoupling structure; and <FIG> is a diagram of comparison, in a simulation experiment, between isolation curves of the antenna decoupling structure-free MIMO antenna (as shown in <FIG>) and the MIMO antenna (as shown in <FIG>) having the antenna decoupling structure <NUM> in <FIG>. In the schematic diagrams of current distribution, a lighter color of a portion of the second antenna unit indicates a greater amount of a current coupled to this portion of the second antenna unit. In <FIG> and <FIG>, S1,<NUM> denotes a curve of a return loss of the first antenna unit; S2,<NUM> denotes a curve of a return loss of the second antenna unit; and S2,<NUM> denotes isolation curves of the first antenna unit and the second antenna unit.

It can be learned, from <FIG>, that for the antenna decoupling structure-free MIMO antenna, a heavy current is coupled to the second antenna unit when the first feed point is exited under excitation conditions of different frequency bands, so that an isolation difference is generated between the first antenna unit and the second antenna unit. With reference to <FIG> and <FIG>, a current is mainly coupled to the LC resonant structure of the antenna decoupling structure <NUM> through the antenna floor <NUM> when the first feed point is excited at the <NUM> frequency band, thereby reducing an amount of the current flowing to the second antenna unit. With reference to <FIG> and <FIG>, a current is mainly coupled to the first decoupling stub <NUM> of the antenna decoupling structure <NUM> through the antenna floor <NUM> when the first feed point is excited at the <NUM> frequency band, thereby reducing an amount of the current flowing to the second antenna unit. With reference to <FIG> and <FIG>, a current is mainly coupled to the second decoupling stub <NUM> of the antenna decoupling structure <NUM> through the antenna floor <NUM> when the first feed point is excited at the <NUM> frequency band, thereby reducing an amount of the current flowing to the second antenna unit. In summary, according to the antenna decoupling structure provided in this embodiment of this application, decoupling for three frequency bands are implemented by using the LC resonant structure, the first decoupling stub <NUM>, and the second decoupling stub <NUM>, respectively, thereby implementing decoupling for a plurality of operating frequency bands. It can be learned, from <FIG> and <FIG>, that the antenna in <FIG> has a plurality of operating frequency bands that can cover the operating frequency bands of the 5GNR antenna: <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM>. It can be learned, from <FIG>, that after the antenna decoupling structure is used, isolations of the antenna at the frequency bands of <NUM>, <NUM>, and <NUM> are greatly increased, thereby completely meeting an isolation requirement.

In summary, according to the antenna provided in this embodiment of this application, the total horizontal length of the antenna can be reduced, so that antenna miniaturization is realized, and decoupling can be implemented at more frequency bands.

Referring to FIG. <FIG> shows dimensions of the foregoing first antenna unit when the first antenna unit is applied to the NR antenna; and <FIG> shows dimensions of an antenna decoupling structure configured to decouple the NR antenna.

As shown in <FIG>, the first floor sub-stub <NUM> extends from the first end of the first floor sub-stub <NUM> in a direction away from the antenna floor <NUM> by b<NUM> (b<NUM>=<NUM>) and in a direction parallel to the antenna floor <NUM> by a first preset distance, sequentially, and is connected to the first end of the second floor sub-stub <NUM>; a distance b<NUM> between a first side edge and a second side edge of the first radiation stub <NUM> is <NUM>, a shortest distance b<NUM> between a second end of the first radiation stub <NUM> and the third groove <NUM> is <NUM>, a distance b<NUM> between a second end of the first radiation stub <NUM> and the second end of the horizontal radiation stub <NUM> is <NUM>, and a distance b<NUM> between a first side edge and a second side edge of the vertical radiation stub <NUM> is <NUM>; and a width b<NUM> of the third groove <NUM> is <NUM>, and a height b<NUM> of the third groove <NUM> is <NUM>. The total length of the floor stub <NUM> and a coupling capacitor composed of a third floor sub-stub <NUM> and the third groove <NUM> form a left-handed antenna mode whose resonant frequency meets a frequency requirement for a first operating frequency band: <NUM>. Both the first radiation stub <NUM> and the second radiation stub <NUM> may be stubs having uniform widths, or may be stubs whose open ends are both wide, as shown in <FIG>. This is not limited in this application.

As shown in <FIG>, the grounding stub <NUM> includes a first grounding sub-stub <NUM>, a second grounding sub-stub <NUM>, and a third grounding sub-stub <NUM>, a first end of the first grounding sub-stub <NUM> is perpendicularly connected to the antenna floor <NUM>, a second end of the first grounding sub-stub <NUM> is perpendicularly connected to a first end of the second grounding sub-stub <NUM>, a second end of the second grounding sub-stub <NUM> is perpendicularly connected to a first end of the third grounding sub-stub <NUM>, and a second end of the third grounding sub-stub <NUM> faces the antenna floor <NUM>; and the capacitive coupling stub 31B includes a third capacitive coupling sub-stub 31B3 and a fourth capacitive coupling sub-stub 31B4, a first end of the third capacitive coupling sub-stub 31B3 is perpendicularly connected to the antenna floor <NUM>, a second end of the third capacitive coupling sub-stub 31B3 is perpendicularly connected to the fourth capacitive coupling sub-stub 31B4, a second groove 31B5 is formed in a side, away from the antenna floor <NUM>, of the fourth capacitive coupling sub-stub 31B4, and the second end of the third grounding sub-stub <NUM> is disposed in the second groove 31B5 and opposite to the second groove 31B5 at an interval, to form a coupling capacitor.

A shortest horizontal distance c<NUM> between a first side edge of the first grounding sub-stub <NUM> and the fourth capacitive coupling sub-stub 31B4 is <NUM>, and a shortest horizontal distance c<NUM> between a second side edge of the first grounding sub-stub <NUM> and the fourth capacitive coupling sub-stub 31B4 is <NUM>. The first side edge of the first grounding sub-stub <NUM> is a side edge perpendicular to the antenna floor <NUM> and close to the fourth capacitive coupling sub-stub 31B4. The second side edge of the first grounding sub-stub <NUM> is a side edge perpendicular to the antenna floor <NUM> and away from the fourth capacitive coupling sub-stub 31B4. A distance c<NUM> between the antenna floor <NUM> and a first side edge of the second grounding sub-stub <NUM> is <NUM>. A distance c<NUM> between the antenna floor <NUM> and a second side edge of the second grounding sub-stub <NUM> is <NUM>. The first side edge of the second grounding sub-stub <NUM> is a side edge parallel to and close to the antenna floor <NUM>. The second side edge of the second grounding sub-stub <NUM> is a side edge parallel to and away from the antenna floor <NUM>.

For example, the length of the first decoupling stub <NUM> may be a quarter of a wavelength corresponding to a center frequency of the second target decoupling frequency band; and the length of the second decoupling stub <NUM> may be a quarter of a wavelength corresponding to a center frequency of the third target decoupling frequency band. However, the first decoupling stub <NUM> and the second decoupling stub <NUM> may be bent for a plurality of times, to reduce horizontal space occupied by the first decoupling stub <NUM> and the second decoupling stub <NUM>.

In an implementation, as shown in <FIG>, the first end of the first decoupling stub <NUM> and the second end of the second grounding sub-stub <NUM> are connected to each other and form a first connection point, and the first decoupling stub <NUM> extends from the first connection point in a direction away from the antenna floor <NUM> by c<NUM> (c<NUM>=<NUM>), in a direction parallel to the antenna floor <NUM> and away from the third capacitive coupling sub-stub 31B3 by c<NUM> (c<NUM>=<NUM>), in a direction away from the antenna floor <NUM> by c<NUM> (c<NUM>=<NUM>), and in a direction parallel to the antenna floor <NUM> and close to the third capacitive coupling sub-stub 31B3 by c<NUM> (c<NUM>=<NUM>), sequentially; and an open end of the second decoupling stub <NUM> is disposed opposite to an open end of the first decoupling stub <NUM>, and the second decoupling stub <NUM> extends from the open end in a direction away from the first decoupling stub <NUM> by c<NUM> (c<NUM>=<NUM>), in a direction close to the antenna floor <NUM> by c<NUM> (c<NUM>=<NUM>), in a direction close to the first decoupling stub <NUM> by c<NUM> (c<NUM>=<NUM>), and in a direction close to and perpendicular to the antenna floor <NUM>, sequentially, and is then connected to the first connection point.

The antenna decoupling structure and the MIMO antenna provided in the embodiments of this application may be applied to a terminal. The terminal may be any device having a wireless communication function, such as a personal computer, a tablet computer, or a mobile phone. This is not limited in this application. For example, the MIMO antenna in <FIG> may be applied to a WIFI tri-band antenna of a terminal notebook computer. For another example, the MIMO antenna in <FIG> may be applied to an NR antenna of a terminal notebook computer.

An implementation process of the antenna decoupling structure and the antenna is not limited in the embodiments of this application. For example, the process may be printing using a printed circuit board (printed circuit board, PCB) or a flexible printed circuit (flexible printed circuit, FPC) or forming through laser-direct-structuring (laser-direct-structuring, LDS). <FIG> is a schematic diagram of a prepared MIMO antenna according to an embodiment of this application. The MIMO antenna in <FIG> includes a first antenna unit <NUM>, a second antenna unit <NUM>, and an antenna decoupling structure <NUM> that are all attached to a dielectric substrate <NUM>. An extended side of the dielectric substrate <NUM> is perpendicular to the antenna floor <NUM>.

Claim 1:
An antenna decoupling structure, comprising a grounding stub (<NUM>), a capacitor structure, a first decoupling stub (<NUM>) and a second decoupling stub (<NUM>), wherein
a first end of the grounding stub is connected to an antenna floor (<NUM>), to form an equivalent inductor; and
a first end of the capacitor structure is connected to the antenna floor, and a second end of the capacitor structure is connected to a second end of the grounding stub, so that the equivalent inductor and the capacitor structure form an LC resonant structure, wherein a parameter corresponding to the LC resonant structure meets a decoupling requirement for a first target decoupling frequency band;
the first decoupling stub and the second decoupling stub are respectively disposed on two sides of the grounding stub;
a first end of the first decoupling stub is connected to the second end of the grounding stub, and a length of the first decoupling stub meets a decoupling requirement for a second target decoupling frequency band; and
a first end of the second decoupling stub is connected to the second end of the grounding stub, and a length of the second decoupling stub meets a decoupling requirement for a third target decoupling frequency band, wherein the first target decoupling frequency band is a lowest frequency band among the first target decoupling frequency band, the second target decoupling frequency band, and the third target decoupling frequency band, characterized in that:
the length of the first decoupling stub is a quarter of a wavelength corresponding to a center frequency of the second target decoupling frequency band;
the length of the second decoupling stub is a quarter of a wavelength corresponding to a center frequency of the third target decoupling frequency band; and
an open end formed after bending of the first decoupling stub is disposed opposite to an open end formed after bending of the second decoupling stub.