A frequency reconfigurable MIMO antenna

Abstract

This application belongs to the field of antenna technology and relates to a frequency-reconfigurable MIMO antenna, comprising: a dielectric layer, a radiating layer disposed on the upper surface of the dielectric layer, and a floor layer disposed on the lower surface of the dielectric layer; the radiating layer comprises: two radiating elements, thereby forming a MIMO antenna; the radiating elements comprise: a radiating patch and a microstrip line connected to the radiating patch; the radiating patch has a "9" structure, wherein the two "9" structures are axially symmetrically distributed, with the openings facing away from each other; a diode and an air band gap are disposed at the closed end of the "9" structure to achieve frequency reconfiguration. The present application can achieve frequency reconfiguration of the MIMO antenna.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to a frequency reconfigurable MIMO antenna. Background Art

[0002] With the rapid development of modern radio equipment and communication systems, the demand for the number of antennas on platforms such as aircraft, ships, and satellites is increasing. This trend not only significantly expands the space occupied by antennas and increases the quality and manufacturing costs of communication systems, but also further aggravates the deterioration of the electromagnetic environment. Therefore, how to achieve high-efficiency transmission and improve system performance within limited spectrum resources has become a key topic in modern antenna research.

[0003] Therefore, MIMO antennas emerged as a result and are gradually becoming one of the core technologies in the field of 5G wireless communications. In existing technologies, MIMO antennas are composed of multiple independent antenna units, which can improve communication capacity and frequency utilization, making a significant contribution to the development of modern communications.

[0004] However, with the rapid development of communication systems in recent years, spectrum resources have gradually decreased, and the rapid increase in the number of antennas has led to a more serious deterioration of electromagnetic compatibility, and the requirements of equipment for antennas have become increasingly higher. In this context, how to further improve transmission efficiency has become a hot research issue. Summary of the Invention

[0005] Based on this, it is necessary to provide a frequency-reconfigurable MIMO antenna to address the above technical problems, which can realize the frequency reconfiguration of the MIMO antenna and improve the transmission efficiency.

[0006] A frequency reconfigurable MIMO antenna comprises: a dielectric layer, a radiation layer arranged on the upper surface of the dielectric layer, and a floor layer arranged on the lower surface of the dielectric layer;

[0007] The radiation layer includes: two radiation units, so that the antenna forms a MIMO antenna;

[0008] The radiation unit includes: a radiation patch and a microstrip line connected to the radiation patch;

[0009] The radiation patch has a "9" structure, with two "9" structures axially symmetrically distributed and the openings facing back to back; a diode and an air band gap are provided on the closed end of the "9" structure to achieve frequency reconfiguration.

[0010] In one embodiment, the "9" structure includes: a first portion, a second portion, and a third portion, all of which are "L"-shaped structures;

[0011] One end of the first part is connected to one end of the second part, the other end of the first part is connected to one end of the third part via a diode, an air gap is provided between the other end of the second part and one end of the third part, and the other end of the third part is connected to the microstrip line.

[0012] In one embodiment, the straight line where the other end of the second portion lies is not collinear with the straight line where one end of the third portion lies.

[0013] In one embodiment, a distance between the first portion and the short side of the dielectric layer is smaller than a distance between the third portion and the short side of the dielectric layer.

[0014] In one embodiment, the microstrip line is connected to a position close to the other end of the third portion.

[0015] In one embodiment, the floor layer is provided on the lower surface of the dielectric layer at a position corresponding to the microstrip line, and the floor layer is a rectangular structure with three sides collinear with the dielectric layer.

[0016] In one embodiment, a decoupling structure is further provided on the lower surface of the dielectric layer;

[0017] The decoupling structure includes: a first component connected to the floor layer;

[0018] The first component is a "T"-shaped structure, and the "T"-shaped structure is arranged at a position corresponding to the symmetry axis on the radiation layer.

[0019] In one embodiment, the "T"-shaped structure includes: a first section and a second section;

[0020] One end of the first section is connected to the floor layer, and the other end is vertically connected to the midpoint of the second section.

[0021] In one embodiment, the decoupling structure further comprises: a second component provided on the floor layer;

[0022] The second component is two L-shaped grooves axially symmetrically distributed about the first component;

[0023] The "L"-shaped groove includes: a first section and a second section; the first section is adjacent to and parallel to the first section; the second section is perpendicular to the first section.

[0024] In one embodiment, the width of the first component is equal to the width of the radiating patch.

[0025] The frequency-reconfigurable MIMO antenna is designed with a radiating layer that can regulate the operating frequency by controlling the switching state of the PIN diode, dynamically adjusting the antenna's resonant frequency so that the antenna operates in two desired modes and three frequency bands, achieving three-band resonant operation and frequency reconfiguration. This increases the antenna's channel width, covers many air interface standards for wireless communications, and better utilizes spectrum resources. It achieves high-efficiency radiation and transmission under limited spectrum resources, with good omnidirectional radiation performance, and can meet the needs of different communication scenarios. At the same time, a decoupling structure is designed to improve the isolation between antenna units, reduce the strong electromagnetic coupling between units, and lower the envelope correlation coefficient, ensuring the normal operation performance of the antenna and good decoupling effect. It also achieves miniaturization, achieves good communication effects, and thus ensures the efficiency and stability of the entire communication system. Compared with the existing technology, in which the mutual influence between antenna units is also enhanced when the antenna size is small, this application has significant advantages. In addition, the MIMO antenna of the present application is designed with a printed monopole antenna as the antenna unit. It is light in weight, small in size, low in cost, compact in structure, and simple to manufacture. It can be widely used in wireless communication system terminals, especially in radio equipment detection, satellite communication, mobile communication and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is an overall schematic diagram of a frequency reconfigurable MIMO antenna in one embodiment;

[0027] Figure 2 is a schematic diagram of a radiating element of a frequency reconfigurable MIMO antenna in one embodiment;

[0028] Figure 3 is a schematic diagram of a decoupling structure of a frequency reconfigurable MIMO antenna in one embodiment;

[0029] Figure 4 An equivalent circuit model of a diode in a conducting state of a frequency reconfigurable MIMO antenna in one embodiment;

[0030] Figure 5 An equivalent circuit model of a diode in a cut-off state of a frequency reconfigurable MIMO antenna in one embodiment;

[0031] Figure 6 This is a surface current distribution diagram of a radiating element of a frequency reconfigurable MIMO antenna at a resonant frequency of 3.67 GHz before loading a diode in one embodiment;

[0032] Figure 7 This is a surface current distribution diagram of a radiating element of a frequency reconfigurable MIMO antenna at a resonant frequency of 5.30 GHz before loading a diode in one embodiment;

[0033] Figure 8 FIG1 is a surface current distribution diagram of a radiation element of a frequency reconfigurable MIMO antenna in mode 1 (resonance frequency 3.67 GHz) after loading a diode in one embodiment;

[0034] Figure 9 FIG1 is a surface current distribution diagram of a radiation element of a frequency reconfigurable MIMO antenna in mode 1 (resonance frequency 5.30 GHz) after loading a diode in one embodiment;

[0035] Figure 10 FIG1 is a surface current distribution diagram of a radiation element of a frequency reconfigurable MIMO antenna in mode 2 (resonance frequency 4.87 GHz) after loading a diode in one embodiment;

[0036] Figure 11 A schematic diagram of the dimensions of a frequency reconfigurable MIMO antenna in one embodiment;

[0037] Figure 12 FIG1 is a schematic diagram of another size of a frequency reconfigurable MIMO antenna in one embodiment;

[0038] Figure 13 FIG1 is an S-parameter diagram of a frequency reconfigurable MIMO antenna in mode 1 according to an embodiment;

[0039] Figure 14 is an S-parameter diagram of a frequency-reconfigurable MIMO antenna in mode 2 according to an embodiment;

[0040] Figure 15 1 is a graph of peak gains of a frequency reconfigurable MIMO antenna in two modes in one embodiment;

[0041] Figure 16 1 is a diagram showing antenna efficiency of a frequency reconfigurable MIMO antenna in two modes according to an embodiment;

[0042] Figure 17 is a graph of envelope correlation coefficients of a frequency reconfigurable MIMO antenna in two modes in one embodiment;

[0043] Figure 18 1 is a diversity gain diagram of a frequency reconfigurable MIMO antenna in two modes in one embodiment;

[0044] Figure 19 is a far-field two-dimensional radiation pattern of a frequency reconfigurable MIMO antenna in mode 1 (resonant frequency 3.67 GHz) in one embodiment;

[0045] Figure 201 is a far-field two-dimensional radiation pattern of a frequency reconfigurable MIMO antenna in mode 1 (resonant frequency 5.30 GHz) in one embodiment;

[0046] Figure 21 1 is a far-field two-dimensional radiation pattern of a frequency reconfigurable MIMO antenna in mode 2 (resonant frequency 4.87 GHz) in one embodiment.

[0047] Reference numerals:

[0048] dielectric layer 1;

[0049] Radiation layer 2, radiation patch 21, first portion 211, second portion 212, third portion 213, microstrip line 22, diode 23, air band gap 24;

[0050] Floor layer 3 , first component 31 , first section 311 , second section 312 , second component 32 , first section 321 , second section 322 . DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in this application without creative work are within the scope of protection of this application.

[0052] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0053] In addition, the terms "first," "second," and so on, used in this application are for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, and so on, unless otherwise specifically defined.

[0054] In this application, unless otherwise specified or limited, the terms "connect," "fix," etc. should be understood in a broad sense. For example, "fix" can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean internal communication between two elements or an interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0055] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0056] This application provides a frequency reconfigurable MIMO antenna, such as Figures 1 to 3 As shown, in one embodiment, it includes: a dielectric layer, a radiation layer and a floor layer.

[0057] The dielectric layer is a supporting component, providing a bearing space for the radiation layer and the floor layer; specifically, the dielectric layer is a rectangular structure, and the two radiation units of the radiation layer are arranged in a mirror image.

[0058] The radiation layer is a radiation component, which is arranged on the upper surface of the dielectric layer, and includes: two radiation units, so that the antenna forms a MIMO antenna; the radiation unit includes: a radiation patch and a microstrip line, and the two ends of the microstrip line are respectively connected to the radiation patch and the edge of the dielectric layer; the radiation patch is in a "9" structure, the two "9" structures are axially symmetrically distributed, and the openings of the two "9" structures are set back to back; a diode (such as a PIN diode) and an air band gap are provided on the closed end of the "9" structure, which can support different current paths to achieve resonance in different frequency bands and frequency reconfiguration, and improve the resonance depth and resonant frequency of the frequency.

[0059] The floor layer is a grounding component and is arranged on the lower surface of the dielectric layer.

[0060] Preferably, the "9" structure includes: a first portion, a second portion, and a third portion; the first portion, the second portion, and the third portion are all "L"-shaped and arranged sequentially; specifically, one end of the first portion is connected to one end of the second portion, the other end of the first portion is connected to one end of the third portion via a diode, an air gap is provided between the other end of the second portion and one end of the third portion, and the other end of the third portion is connected to a microstrip line. This arrangement can achieve dual-frequency resonance and increase the resonance depth.

[0061] Further preferably, the straight line where the other end of the second part is located is not collinear with the straight line where one end of the third part is located, so as to improve S 11 performance, increasing resonance depth.

[0062] More preferably, the distance between the first portion and the short side of the dielectric layer is smaller than the distance between the third portion and the short side of the dielectric layer, so as to further increase the resonance depth.

[0063] Further preferably, the microstrip line is connected to a position near the other end of the third part, and in the horizontal and vertical directions, the distance between the microstrip line and the first part is smaller than the distance between the microstrip line and the second part, so as to change the current path of the electromagnetic wave, ensure the resonance depth and resonance frequency at the high frequency when the PIN diode is turned on, and realize multi-band operation.

[0064] In another embodiment, the floor layer is provided on the lower surface of the dielectric layer at a position corresponding to the microstrip line, and the floor layer is a rectangular structure with three sides collinear with the dielectric layer to achieve grounding and improve impedance matching of the monopole antenna.

[0065] Preferably, the length of the floor layer is equal to the length of the dielectric layer, the width of the floor layer is smaller than the width of the dielectric layer, the width of the floor layer is greater than the length of the microstrip line, and the floor layer partially overlaps with the third part of the radiation patch to ensure the resonant frequency of multiple bands, especially the resonant frequency at low frequencies, and expand the resonant frequency band.

[0066] In another embodiment, a decoupling structure is further provided on the lower surface of the dielectric layer. The decoupling structure includes a first component connected to the floor layer; the first component is a T-shaped structure positioned corresponding to the axis of symmetry on the radiating layer. The provision of the first component can provide an additional current path, effectively reducing the current flow from the excitation port to the non-excitation port, and improving the isolation between the radiating elements.

[0067] Preferably, the "T"-shaped structure includes: a first section and a second section; one end of the first section is connected to the floor layer, and the other end is vertically connected to the midpoint of the second section to further provide an additional shunt path, effectively reducing the mutual coupling effect and filtering out the coupling current on the floor layer.

[0068] Further preferably, the length of the first section is greater than the length of the second section, so as to increase the resonance depth and improve the isolation of the antenna at low frequencies.

[0069] More preferably, the decoupling structure further includes: a second component disposed on the floor layer; the second component comprises two L-shaped slots axially symmetrically distributed about the first component; the L-shaped slots comprise a first section and a second section; the first section is adjacent to and parallel to the first segment, the length of the first section being less than the width of the floor layer; the second section is perpendicular to the first section, that is, perpendicular to the first segment and parallel to the second segment; the widths of the first segment, the second segment, the first section, and the second section are all equal. The second component can filter out surface wave currents on the floor, thereby further improving the isolation between the two antenna units and achieving high antenna isolation.

[0070] Further preferably, the length of the second section is greater than that of the first section, and the length of the second section is greater than that of the second segment, so as to avoid coupling with the radiation patch, increase the high-frequency resonance frequency and depth, and enable the antenna to maintain good isolation at both low and high frequencies.

[0071] More preferably, the width of the first component is equal to the width of the radiation patch (all parts of the radiation patch are of equal width) to improve the coupling degree of the antenna, avoid the generation of new resonance modes, maintain the continuity of the electromagnetic field distribution, and ensure the resonance depth.

[0072] In this application, the circuit characteristics of the PIN diode are different in different working states.

[0073] like Figure 4 and Figure 5 As shown in the figure, when conducting, a PIN diode is equivalent to an RL series resonant circuit, with an inductor and a resistor in series. When off, it is equivalent to an RLC parallel resonant circuit, with a resistor and a capacitor in parallel, which are then connected in series with the inductor. Based on this characteristic of the PIN diode, changing the voltage across the diode can change the on-off state of the PIN diode, thereby changing the structure of the antenna, distributing the current in different parts and achieving antenna reconfiguration.

[0074] Table 1 shows the different mode combinations caused by the switching state of the PIN diode. When using simulation software to simulate the working state of the PIN diode, a very small resistor can be used to represent the forward-biased state of the PIN diode, and a high-resistance capacitor can be used to represent the reverse-biased state of the PIN diode, thereby simulating the conduction and cutoff of the PIN diode.

[0075] Table 1: Different mode combinations resulting from PIN diode switching states

[0076]

[0077] like Figure 6 and Figure 7As shown, analysis shows that when the antenna works at 3.67GHz, the current intensity of the horizontal section of the second part and the vertical section of the third part of the antenna radiation patch is relatively large, which is consistent with the characteristic of long resonant branches in the low frequency band; when the antenna is switched to 5.30GHz, the current intensity of the third part of the antenna radiation patch is relatively large, which is consistent with the characteristic of short resonant branches in the high frequency band. It can be seen that the current distribution intensity at the edge of the branch at the two resonant frequencies is larger than that of other parts, and it is also particularly obvious at the turning point of the branch. This is because the electromagnetic waves radiated by the microstrip antenna generally come from non-continuous parts such as the turning point of the oscillator, open ports or mutations; in addition, the current distribution shown in the figure also confirms the 3.67GHz and 5.30GHz λ The lengths of the / 4 current paths are 21.35 mm and 13.15 mm respectively. High frequencies are generated by shorter antenna branches, and low frequencies are generated by longer antenna branches, which are consistent with the size range of theoretical calculations (the specific theoretical calculations belong to the existing technology).

[0078] like Figure 8 and Figure 9 As shown in Figure 1, the surface current distribution of the radiating unit in dual frequency mode 1 is Figure 6 as well as Figure 7 resemblance.

[0079] like Figure 10 As shown in Figure 2, in Mode 2, the PIN diode disconnects the capacitor, which is equivalent to a high resistor, and blocks the current from flowing to the longer low-frequency oscillator. The current is mainly distributed in the high-frequency oscillator. Therefore, in Mode 2, the antenna resonates only at a frequency of 4.87 GHz.

[0080] The frequency-reconfigurable MIMO antenna is designed with a radiating layer that can regulate the operating frequency by controlling the switching state of the PIN diode, dynamically adjusting the antenna's resonant frequency so that the antenna operates in two desired modes and three frequency bands, achieving three-band resonant operation and frequency reconfiguration. This increases the antenna's channel width, covers many air interface standards for wireless communications, and better utilizes spectrum resources. It achieves high-efficiency radiation and transmission under limited spectrum resources, with good omnidirectional radiation performance, and can meet the needs of different communication scenarios. At the same time, a decoupling structure is designed to improve the isolation between antenna units, reduce the strong electromagnetic coupling between units, and lower the envelope correlation coefficient, ensuring the normal operation performance of the antenna and good decoupling effect. It also achieves miniaturization, achieves good communication effects, and thus ensures the efficiency and stability of the entire communication system. Compared with the existing technology, in which the mutual influence between antenna units is also enhanced when the antenna size is small, this application has significant advantages. In addition, the MIMO antenna of the present application is designed with a printed monopole antenna as the antenna unit. It is light in weight, small in size, low in cost, compact in structure, and simple to manufacture. It can be widely used in wireless communication system terminals, especially in radio equipment detection, satellite communication, mobile communication and other fields.

[0081] In a specific embodiment, Figure 11 and Figure 12 As shown, the dielectric layer is made of FR4 material with parameters of εr=4.4, tanδ=0.02, length and width are both 25mm, and thickness H=0.8mm.

[0082] The size parameters are shown in Tables 2 and 3.

[0083] Table 2: Dimensional parameters 1

[0084]

[0085] Table 3: Dimensional parameters 2

[0086]

[0087] like Figure 13 and Figure 14 As shown, the S at the resonant frequency in the two modes 11 Both are less than -10dB, indicating that the antenna has a good matching effect at the resonant frequency. In Mode 1, the antenna resonates in the dual frequency bands of 3.67GHz and 5.30GHz; in Mode 2, the antenna resonates in the frequency band of 4.87GHz. 21 The value reflects the mutual coupling between antenna units. The S value of the center resonant frequency of the antenna in Mode 1 and Mode 2 is21 The values ​​are all less than -10dB.

[0088] like Figure 15 As shown in the figure, it can be seen that the peak gains of the antenna in its operating frequency band are: 3.16~3.48dBi in the 3.59~3.72GHz band of mode 1, 4.70~5.08dBi in the 5.14~5.55GHz band of mode 1, and 2.01~3.92dBi in the 4.45~5.23GHz band of mode 2. The antenna radiation performance is good.

[0089] like Figure 16 As shown in Figure 1, the highest antenna radiation efficiency in Mode 1 and Mode 2 operating frequencies reaches 98.01% and 97.33% respectively.

[0090] like Figure 17 As shown, it can be seen that the envelope correlation coefficient (ECC) value of the antenna is maintained below 0.03 within the operating frequency band. This value is much lower than the 0.5 threshold usually required for MIMO antennas, indicating that the diversity performance of the MIMO antenna in this application is good.

[0091] like Figure 18 As shown in the figure, it can be seen that for the two modes, the diversity gain (DG) values ​​of the antenna in the working frequency band are both within 9.8~10.0dB, showing good diversity benefits.

[0092] like Figures 19 to 21 As shown in the figure, when the antenna operates in Mode 1 (5.30 GHz), the radiation patterns of the E-plane and H-plane of the antenna are approximately in the shape of an "8". When operating in Mode 1 (3.65 GHz) and Mode 2 (4.87 GHz), the radiation patterns of the E-plane and H-plane of the antenna are basically circular, showing omnidirectional radiation characteristics, indicating that the radiation power of the two frequency bands covers the surrounding area well, ensuring wide coverage and efficient transmission of the antenna signal.

[0093] In summary, the overall size of the antenna of the present application is 25mmx50mm, which can realize frequency reconfiguration of mode 1 (3.59~3.72GHz, 5.14~5.55GHz) and mode 2 (4.45~5.23GHz), and has a short response delay and compact design; through frequency reconstruction, the antenna operating frequency band covers three frequency bands: 3.59~3.72GHz, 5.14~5.55GHz, and 4.45~5.23GHz; when the PIN diode is turned on, the antenna operates in the 3.59~3.72GHz and 5.14~5.55GHz bands, with resonant frequencies of 3.67GHz and 5.30GHz respectively, the antenna efficiency is as high as 98.01%, and the peak gain of the antenna at the operating frequency is 2.5%. The antenna achieves a gain of 5.08 dBi. When the PIN diode is cut off, the antenna operates in the 4.45-5.23 GHz frequency band with a resonant frequency of 4.87 GHz. The antenna efficiency reaches 97.33%, and the peak gain at the operating frequency reaches 3.92 dBi. The added decoupling structure improves isolation by 10 dB. The antenna achieves isolation better than 10 dB across the operating frequency band, with a maximum isolation of 18 dB. This excellent decoupling performance ensures high isolation. The antenna's envelope correlation coefficient is less than 0.03 in both operating modes, and the diversity gain is between 9.8 and 10 dB. The antenna exhibits excellent radiation performance, high diversity gain, and good performance. The antenna's radiation pattern is circular, enabling omnidirectional radiation. Overall, the antenna features a simple structure, multiple operating frequency bands, and high isolation.

[0094] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0095] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A frequency reconfigurable MIMO antenna, characterized in that: include: A dielectric layer, a radiation layer provided on the upper surface of the dielectric layer, and a floor layer provided on the lower surface of the dielectric layer; The radiation layer includes: two radiation units, so that the antenna forms a MIMO antenna; The radiation unit includes: a radiation patch and a microstrip line connected to the radiation patch; The radiating patch is in a "9" structure, with two "9" structures axially symmetrically distributed and the openings facing each other. A diode and an air band gap are provided at the closed end of the "9" structure to achieve frequency reconfiguration. The "9" structure includes: a first part, a second part and a third part, all of which are "L" shaped structures; One end of the first part is connected to one end of the second part, the other end of the first part is connected to one end of the third part via a diode, an air gap is provided between the other end of the second part and one end of the third part, and the other end of the third part is connected to the microstrip line; The straight line where the other end of the second portion lies is not collinear with the straight line where one end of the third portion lies.

2. The frequency reconfigurable MIMO antenna according to claim 1, wherein: The distance between the first portion and the short side of the dielectric layer is smaller than the distance between the third portion and the short side of the dielectric layer.

3. The frequency reconfigurable MIMO antenna according to claim 2, wherein: The microstrip line is connected to a position close to the other end of the third part.

4. The frequency reconfigurable MIMO antenna according to any one of claims 1 to 3, characterized in that: The floor layer is arranged on the lower surface of the dielectric layer at a position corresponding to the microstrip line, and the floor layer is a rectangular structure with three sides collinear with the dielectric layer.

5. The frequency reconfigurable MIMO antenna according to any one of claims 1 to 3, characterized in that: A decoupling structure is also provided on the lower surface of the dielectric layer; The decoupling structure includes: a first component connected to the floor layer; The first component is a "T"-shaped structure, and the "T"-shaped structure is arranged at a position corresponding to the symmetry axis on the radiation layer.

6. The frequency reconfigurable MIMO antenna according to claim 5, characterized in that: The "T"-shaped structure includes: a first section and a second section; One end of the first section is connected to the floor layer, and the other end is vertically connected to the midpoint of the second section.

7. The frequency reconfigurable MIMO antenna according to claim 6, characterized in that: The decoupling structure further includes: a second component provided on the floor layer; The second component is two "L"-shaped grooves axially symmetrically distributed about the first component; The "L"-shaped groove includes: a first section and a second section; the first section is adjacent to and parallel to the first section; the second section is perpendicular to the first section.

8. The frequency reconfigurable MIMO antenna according to claim 7, characterized in that: The width of the first component is equal to the width of the radiation patch.

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