A liquid medium based high-isolation reconfigurable four-port MIMO slot antenna

Abstract

The application discloses a liquid medium-based high-isolation reconfigurable four-port MIMO slot antenna, which comprises a MIMO antenna layer, a liquid medium layer and a floor layer arranged in sequence from top to bottom, wherein the MIMO antenna layer is parallel to the floor layer, the MIMO antenna layer and the floor layer are connected through a coaxial feeder, four slot antennas are arranged on the MIMO antenna layer, and the four slot antennas are arranged in sequence by rotating around a center point by 90 degrees; the application realizes the reconfigurable MIMO antenna by loading a medium container and a ring-shaped neutral line, analyzes the equivalent dielectric constant of different liquid contents in the medium container by using an equivalent capacitance model method, adjusts the volume of the liquid material to change the equivalent dielectric constant of the medium container, changes the equivalent wavelength of the radiation and decoupling structure of the antenna, and thus realizes the characteristics that the antenna has good matching and high isolation on different frequency bands, and simultaneously satisfies the reconfigurable characteristics of frequency and isolation.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium. Background Technology

[0002] With the rapid development of communication technology and the surge in user demand, wireless communication systems are evolving towards miniaturization, multifunctionality, and high capacity. As a crucial component of communication equipment, antennas need to operate across multiple frequency bands to achieve multifunctional and multi-mode signal transmission. However, they also need to address challenges such as compact layout, severe coupling, and electromagnetic interference resulting from increased antenna density. Reconfigurable and decoupling technologies can effectively address these challenges, providing new ideas and solutions for future communication system design. Reconfigurable antennas can reconfigure various electrical parameters in real time according to different system requirements, changing the antenna's operating state—essentially using a single antenna to perform the functions of multiple antennas to adapt to diverse application environments. Therefore, reconfigurable antennas offer advantages over traditional antennas, increasing the system's operating frequency band coverage and compressing the space of MIMO (multiple-input multiple-output) communication systems, thus improving integration. However, switch-based reconfigurable designs, such as electrically reconfigurable and optically reconfigurable designs, typically operate in discrete states, limiting their reconfigurability. Furthermore, as communication systems become increasingly integrated, the mutual coupling between antennas becomes a critical issue. Combining reconfigurable design with decoupling technology can achieve reconfigurable characteristics in terms of operating frequency and isolation.

[0003] In recent years, liquid reconfigurable antennas have attracted widespread attention. Liquid materials possess properties such as fluidity, adaptability, stability, flexibility, low cost, and scalability. Compared with switching antennas, liquid reconfigurable antennas can achieve continuous reconfigurability. However, most common liquid antennas are terminal single antennas, and research on liquid reconfigurable MIMO array antennas is relatively limited.

[0004] Regarding the frequency and isolation reconfigurability of MIMO antennas, the invention with patent publication number CN114843762A discloses a frequency reconfigurable four-port MIMO antenna. This antenna achieves frequency reconfigurability by switching on and off a PIN diode, exhibits good radiation characteristics at 2.5GHz and 3.0GHz, and utilizes an EBG structure to achieve high isolation between adjacent antenna elements.

[0005] However, to achieve high isolation and tunability, current reconfigurable antennas are mainly divided into two categories: switch-based antennas, which focus on using electronic devices such as PIN diodes and varactor diodes to adjust the antenna structure and achieve reconfigurable frequency, polarization, or radiation pattern; and non-switch-based antennas, which rely on the properties of some novel materials to achieve reconfigurability by changing the material properties. Switch-based reconfigurable techniques are typically limited to discrete frequency bands and polarization states, resulting in limited reconfiguration capabilities. Material-based tunability techniques offer better reconfiguration capabilities but are less commonly used in MIMO array antennas. Furthermore, to address the challenges of compact layout and severe coupling caused by increased antenna density, array antennas need to suppress the mutual coupling between antenna elements.

[0006] In summary, existing technologies typically involve mounting RF MEMS systems, PIN diodes, and capacitors onto the antenna as switching devices, combined with decoupling techniques such as decoupling networks to achieve frequency and isolation reconfigurable MIMO antennas. While PIN diode-based switching designs can increase antenna bandwidth, functionality, and system capacity, they significantly increase design complexity and size, making control more difficult and limiting reconfigurability. Material-based reconfigurable technologies offer better reconfiguration capabilities but are less commonly used in MIMO array antenna design. Furthermore, traditional decoupling designs for miniaturized reconfigurable MIMO antennas struggle to achieve wideband or multi-band decoupling. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to provide a high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium. The present invention realizes a reconfigurable MIMO antenna by loading a dielectric container and a ring neutralization line. Using the equivalent capacitance model method, the equivalent dielectric constant of different liquid contents in the dielectric container is analyzed. The volume of the liquid material is adjusted to change the equivalent dielectric constant of the dielectric container, thereby changing the equivalent wavelength of the antenna's radiation and decoupling structure. This achieves good matching and high isolation characteristics of the antenna in different frequency bands, while satisfying the reconfigurable characteristics of frequency and isolation.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium includes a MIMO antenna layer 1, a liquid medium layer 2, and a ground plane layer 3 placed sequentially from top to bottom. The MIMO antenna layer 1 is parallel to the ground plane layer 3 and the MIMO antenna layer 1 and the ground plane layer 3 are connected by a coaxial feed line. Four slot antennas are arranged on the MIMO antenna layer 1, and the four slot antennas are arranged sequentially by rotating 90 degrees around the center point.

[0010] The MIMO antenna layer 1 includes a top dielectric substrate 5 with chamfered corners, a radiating structure 4 printed on the upper surface of the top dielectric substrate 5, and a decoupling structure 6 printed on the lower surface of the top dielectric substrate 5.

[0011] The liquid medium layer 2 includes a medium container 15 with a filling hole and a liquid material 16 located in the medium container 15.

[0012] The radiating structure 4 includes rectangular slots 9 located on the upper surface of the top dielectric substrate 5 and respectively arranged perpendicular to its four chamfered corners, and grounded coplanar waveguide feed lines 10 arranged perpendicular to the four rectangular slots 9 respectively. The ends of the rectangular slots 9 are connected to the circular slots 12 located at the center of the top dielectric substrate 5, and the rectangular slots 9 are separated by non-radiating rectangular slots 11.

[0013] The floor layer 3 includes a bottom dielectric substrate 8 placed horizontally at the bottom and four coaxial connectors 7 located on the bottom dielectric substrate 8. The coaxial connectors 7 are respectively connected to four corresponding grounded coplanar waveguide feed lines 10 through coaxial feed lines.

[0014] The area of ​​the bottom dielectric substrate 8 is (48.0-70.0mm)*(48.0-70.0mm), and the thickness is 0.254-0.508mm.

[0015] The decoupling structure 6 includes an annular neutralization line 13 printed on the lower surface of the top dielectric substrate 5 and a metal via 14 located inside the top dielectric substrate 5. The annular neutralization line 13 is connected to the midpoint of the long side of the non-radiative rectangular slit 11 of the radiating structure 4 through the metal via 14.

[0016] The medium container 15 is a hollow cylinder with a bottom radius of 18.20-20.40 mm, a height of 4.80-7.60 mm, and a container wall thickness of 0.80-1.20 mm.

[0017] The height of the liquid material 16 is 0.52mm-3.80mm, the filling rate p is 0.13-0.95, and the liquid material 16 is ethanol.

[0018] The overall profile height of the antenna is 5.80-8.60mm; the area of ​​the top dielectric substrate 5 is (42.0-48.0mm)*(42.0-48.0mm), the chamfer width is 9.50-12.50mm, and the thickness is 0.254-0.508mm.

[0019] The rectangular slot 9 has a length of 9.0-12.0 mm and a width of 3.20-3.80 mm; the grounded coplanar waveguide feed line 10 has a length of 11.50-14.50 mm and a width of 1.05-1.35 mm, and the center distance of the grounded coplanar waveguide feed line 10 from the opening of the rectangular slot 9 is 2.20-3.10 mm; the non-radiative rectangular slot 11 has a length of 9.80-14.20 mm and a width of 4.60-6.10 mm; and the circular slot 12 has a radius of 14.20-16.80 mm.

[0020] The inner ring radius of the annular neutralization line 13 is 10.20-13.40 mm, and the ring width of the annular neutralization line 13 is 0.40-0.80 mm; the radius of the metal through hole 14 is 0.25-0.50 mm.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. The present invention achieves continuous reconfigurable characteristics by changing the filling rate of liquid material 16 in the medium container 15, without increasing the size of the antenna radiator, and can achieve a wide frequency tunable range (2.80 to 3.70 GHz, with a relative tunable range of 27.7%) with a small container volume.

[0023] 2. By loading a ring neutral line 13 structure, the current conducted through the ring neutral line 13 can cancel the coupling current between the two antennas at a small spacing (d=0.233λ0, f0=3.30GHz), thereby improving the port isolation and achieving good high isolation characteristics (≥15dB) for the antenna in different frequency bands, while satisfying the reconfigurable characteristics of operating frequency and isolation.

[0024] 3. This invention does not load switch-type electronic devices, so it will not produce negative effects caused by electronic components. By loading the liquid dielectric layer 2 and the decoupling structure 6, a reconfigurable antenna with high isolation is achieved. Moreover, the equivalent working dimensions of each part of the liquid reconfigurable antenna will change synchronously, which can minimize the distortion of the antenna pattern.

[0025] 4. The MIMO antenna proposed in this invention has the characteristics of simple structure and miniaturization. By connecting the end of the rectangular slot 9 to the circular slot 12, the frequency band is widened to the low frequency, realizing broadband operation. Its compact structural size (0.45λ×0.45λ@3.3GHz) is suitable for wireless communication systems.

[0026] In summary, the high-isolation frequency-reconfigurable four-port MIMO array antenna proposed in this invention achieves continuous frequency reconfigurability by adjusting the content of liquid material 16 in the dielectric container 15 to change the equivalent dielectric constant without increasing the radiator size. This solves the problem of limited reconfiguration capability and limitations of current reconfigurable antennas. Since the equivalent working dimensions of each part of the liquid reconfigurable antenna will change synchronously, by loading the ring neutralization line 13, the distortion of the antenna pattern can be minimized while achieving high-isolation reconfigurability. For miniaturization design, this invention uses the idea of ​​widening the end of the slot to connect the rectangular slot 9 to the circular slot 12 located in the center of the top dielectric substrate 5 to broaden the frequency band to low frequencies, achieving a compact structural size. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the antenna of the present invention.

[0028] Figure 2 This is a side view of the antenna structure of the present invention.

[0029] Figure 3 is a schematic diagram of the MIMO antenna layer structure of the present invention, wherein Figure 3(a) is a schematic diagram of the radiation structure 4 of the present invention, and Figure 3(b) is a schematic diagram of the decoupling structure 6 of the present invention.

[0030] Figure 4 This is a schematic diagram of the structure of the liquid medium layer 2 of the present invention.

[0031] Figure 5 This is a return loss curve of the liquid material 16 in the medium container 15 of the present invention under different filling rates P.

[0032] Figure 6 shows the S-parameters and envelope correlation coefficients of the liquid material 16 in the medium container 15 of the present invention at several filling ratios P; wherein, Figure 6(a) shows the S-parameters and envelope correlation coefficients of the liquid material 16 in the medium container 15 of the present invention at a filling ratio P = 0.13, Figure 6(b) shows the S-parameters and envelope correlation coefficients of the liquid material 16 in the medium container 15 of the present invention at a filling ratio P = 0.78, and Figure 6(c) shows the S-parameters and envelope correlation coefficients of the liquid material 16 in the medium container 15 of the present invention at a filling ratio P = 0.95.

[0033] Figure 7 shows the radiation patterns of the resonant frequencies of the liquid material 16 in the medium container 15 of the present invention at several fill ratios P. Among them, Figure 7(a) shows the radiation pattern of the liquid material 16 in the medium container 15 of the present invention at a resonant frequency of 3.70 GHz at a fill ratio P = 0.13, Figure 7(b) shows the radiation pattern of the liquid material 16 in the medium container 15 of the present invention at a resonant frequency of 3.30 GHz at a fill ratio P = 0.78, and Figure 7(c) shows the radiation pattern of the liquid material 16 in the medium container 15 of the present invention at a resonant frequency of 2.80 GHz at a fill ratio P = 0.95.

[0034] The components are as follows: 1. MIMO antenna layer; 2. Liquid dielectric layer; 3. Ground layer; 4. Radiation structure; 5. Top dielectric substrate; 6. Decoupling structure; 7. Coaxial connector; 8. Bottom dielectric substrate; 9. Rectangular slot; 10. Grounded coplanar waveguide feed line; 11. Non-radiating rectangular slot; 12. Circular slot; 13. Ring neutralization line; 14. Metal via; 15. Dielectric container; 16. Liquid material. Detailed Implementation

[0035] The technical solution adopted by the present invention will be described in detail below with reference to the accompanying drawings.

[0036] like Figure 1 , Figure 2 As shown, a high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium includes a MIMO antenna layer 1, a liquid medium layer 2, and a ground plane layer 3 placed sequentially from top to bottom. The MIMO antenna layer 1 is parallel to the ground plane layer 3 and the MIMO antenna layer 1 and the ground plane layer 3 are connected by a coaxial feed line. Four slot antennas are arranged on the MIMO antenna layer 1, and the four slot antennas are arranged sequentially by rotating 90 degrees around the center point.

[0037] The MIMO antenna layer 1 includes a top dielectric substrate 5 with chamfered corners. A radiating structure 4 is printed on the upper surface of the top dielectric substrate 5, and a decoupling structure 6 is printed on the lower surface of the top dielectric substrate 5. The material of the top dielectric substrate 5 is FR4.

[0038] The overall profile height of the antenna is 7.00 mm. The radiating structure 4 and the decoupling structure 6 are both metal layers and are printed on the upper and lower surfaces of the top dielectric substrate 5 using PCB technology. The top dielectric substrate 5 has an area of ​​45.0 mm * 45.0 mm, a chamfer width of 11.00 mm, and a thickness of 0.500 mm.

[0039] As shown in Figure 3(a), the radiating structure 4 includes four rectangular slots 9 located on the upper surface of the top dielectric substrate 5 and respectively set perpendicular to its four chamfered corners and serving as radiators, and four grounded coplanar waveguide feed lines 10 respectively placed perpendicular to the four rectangular slots 9. The grounded coplanar waveguide feed lines 10 are used to couple and feed the rectangular slots 9. The ends of the four rectangular slots 9 are connected to the circular slot 12 located in the center of the top dielectric substrate 5 to achieve the effect of widening the frequency band. The rectangular slots 9 are separated by non-radiating rectangular slots 11.

[0040] The rectangular slot 9 has a length of 10.0 mm and a width of 3.50 mm; the grounded coplanar waveguide feed line 10 has a length of 13.00 mm and a width of 1.20 mm, and the center of the grounded coplanar waveguide feed line 10 is 2.50 mm away from the opening of the rectangular slot 9; the non-radiative rectangular slot 11 has a length of 10.80 mm and a width of 5.50 mm; the circular slot 12 has a radius of 16.00 mm; the inner ring radius of the annular neutralization line 13 is 11.40 mm, and the ring width of the annular neutralization line 13 is 0.60 mm; the metal through hole 14 has a radius of 0.30 mm.

[0041] As shown in Figure 3(b), the decoupling structure 6 includes an annular neutralization line 13 printed on the lower surface of the top dielectric substrate 5 and a metal via 14 located inside the top dielectric substrate 5. The annular neutralization line 13 is connected to the midpoint of the long side of the non-radiative rectangular slot 11 of the radiating structure 4 (i.e., the point of maximum coupling current) through the metal via 14. The current conducted through the annular neutralization line 13 can cancel the coupling current between two adjacent rectangular slots 9, thereby improving the port isolation and realizing in-band decoupling.

[0042] The floor layer 3 includes a bottom dielectric substrate 8 placed horizontally at the bottom and four coaxial connectors 7 located on the bottom dielectric substrate 8. The four coaxial connectors 7 are respectively connected to four corresponding grounded coplanar waveguide feed lines 10 through coaxial feed lines. The material of the bottom dielectric substrate 8 is FR4.

[0043] The bottom dielectric substrate 8 has an area of ​​50.0mm*50.0mm and a thickness of 0.500mm.

[0044] like Figure 4 As shown, the liquid medium layer 2 includes a medium container 15 with filling holes and a liquid material 16 located in the medium container 15.

[0045] The medium container 15 is a hollow cylinder with a bottom radius of 20.00 mm and a height of 6.00 mm. The container wall thickness of the medium container 15 is 1.00 mm. It is printed using 3D printing technology with PC material, which has a dielectric constant of 2.7 and a loss tangent of 0.02. A filling hole with a diameter of 1.5 mm is opened in the center of the upper wall of the medium container 15 for injecting liquid material 16.

[0046] The height of the liquid material 16 is 0.52mm-3.80mm, the filling rate p is 0.13-0.95, the liquid material 16 is ethanol, and the dielectric constant is 25.

[0047] like Figure 5 As shown, the return loss diagram of the liquid material 16 in the dielectric container 15 under different filling ratios P ​​is given. It can be seen that by adjusting the filling ratio P of the liquid material 16 from 0.13 to 0.95, the resonant frequency of the reconfigurable antenna can be varied between 3.70 GHz and 2.80 GHz, with a maximum frequency tuning range of 27.7%, realizing continuous frequency reconfigurability characteristics in a wide bandwidth.

[0048] As shown in Figures 6(a)-(c), the S-parameters and envelope correlation coefficients of the liquid material 16 in the medium container 15 are given under several fill ratios P ​​(P=0.13, P=0.78, P=0.95). It can be seen that the coupling between adjacent radiating elements of the MIMO antenna in the reconfigurable frequency band is less than -15dB, which shows high port isolation. Secondly, the envelope correlation coefficient (ECC) between adjacent radiating elements in each frequency band is less than 0.05, indicating that the independence of the decoupling ports is good. Within the tuning range, the antenna can obtain good MIMO diversity performance.

[0049] Figures 7(a)-(c) show the radiation patterns of the liquid material 16 in the dielectric container 15 at several filling ratios P ​​(P = 0.13, P = 0.78, P = 0.95) corresponding to the resonant frequencies. It can be seen that the antenna exhibits good radiation characteristics in all three operating states. As shown in Figure 7(a), when the filling ratio P of the liquid material 16 in the dielectric container 15 is 0.13, the resonant frequency of the antenna is 3.70 GHz. The corresponding antenna pattern indicates that the antenna has stable radiation performance at the resonant frequency.

[0050] The liquid reconfigurability proposed in this invention is achieved by adjusting the filling rate of the liquid material 16 in the medium container 15. Ethanol is used as the liquid material. The MIMO antenna can still achieve its purpose when different liquid materials are selected. Selecting a material with a higher dielectric constant, lower loss, and more stable performance can further broaden the reconfigurable tuning range and improve the antenna's radiation performance. Furthermore, by changing or combining other decoupling techniques (the ring neutralization line 13), the MIMO antenna can also achieve its purpose.

[0051] The high isolation frequency reconfigurable MIMO antenna proposed in this invention is characterized by a dielectric container 15 filled with liquid material 16, a ring neutralization line decoupling structure (ring neutralization line 13), and a miniaturized radiating structure (radiating structure 4).

[0052] Furthermore, the dielectric container 15 provides reconfigurable conditions for the antenna. Adjusting the filling rate P of the liquid material 16 in the dielectric container 15 can change its equivalent dielectric constant, thereby achieving continuous frequency reconfigurable characteristics.

[0053] The ring neutral line decoupling structure (ring neutral line 13) can effectively improve the isolation in the reconfigurable frequency band. The current conducted through the ring neutral line 13 can cancel the coupling current between adjacent antennas and suppress the coupling between adjacent units.

[0054] The miniaturized radiating structure (radiating structure 4) includes a rectangular slot antenna (rectangular slot 9), a grounded coplanar waveguide feed line 10, a non-radiating slot 11, and a circular slot 12. Connecting the four rectangular slot antennas (rectangular slots 9) to the circular slot 12 located in the center can effectively improve the operating bandwidth, extend the frequency band to low frequencies, and realize the miniaturized design of the antenna (0.45λ×0.45λ@3.3GHz).

[0055] Furthermore, the medium container 15 is printed using 3D printing technology, and the printing material is PC material with a dielectric constant of 2.7 and a loss tangent of 0.02; the liquid material 16 is ethanol with a dielectric constant of 25.

[0056] Application prospects of this invention:

[0057] This invention can be applied to the design of high-isolation frequency-reconfigurable antennas in MIMO communication systems, enabling the array antenna to operate over a wide tuning range while maintaining high isolation.

[0058] Traditional switch-type reconfigurable antennas generally have limited reconfiguration capabilities and are difficult to control. In contrast, the frequency and isolation reconfigurable MIMO antenna based on liquid materials in this invention has a simple structure, is easy to implement, and can achieve continuous frequency reconfigurability and high isolation. When applied to novel wireless communication systems, it can significantly reduce system complexity and improve system capacity and performance.

[0059] Previous reconfigurable antennas could adapt to various communication standards, but they suffered from negative impacts on electronic components, resulting in higher losses and costs. The present invention proposes a reconfigurable antenna achieved by loading a dielectric container filled with liquid material between the antenna layer and the ground plane. This material offers advantages such as strong adaptability, good scalability, and low cost. Furthermore, the neutralization line structure proposed in this invention achieves wideband decoupling using a single structure, maintaining high isolation throughout the reconfigurable frequency band. In addition, the equivalent operating dimensions of each part of the antenna change synchronously, thus minimizing antenna pattern distortion.

Claims

1. A high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium, characterized in that: The MIMO antenna layer (1), liquid medium layer (2) and ground layer (3) are placed from top to bottom. The MIMO antenna layer (1) is parallel to the ground layer (3) and the MIMO antenna layer (1) and the ground layer (3) are connected by a coaxial feed line. Four slot antennas are provided on the MIMO antenna layer (1) and the four slot antennas are arranged in sequence around the center point by rotating 90 degrees. The MIMO antenna layer (1) includes a top dielectric substrate (5) with chamfered edges. A radiating structure (4) is printed on the upper surface of the top dielectric substrate (5), and a decoupling structure (6) is printed on the lower surface of the top dielectric substrate (5). The radiation structure (4) includes rectangular slots (9) located on the upper surface of the top dielectric substrate (5) and perpendicular to its four corners, and grounded coplanar waveguide feed lines (10) placed perpendicular to the four rectangular slots (9). The ends of the rectangular slots (9) are connected to the circular slots (12) located in the center of the top dielectric substrate (5). The rectangular slots (9) are separated by non-radiating rectangular slots (11).

2. The high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium according to claim 1, characterized in that: The liquid medium layer (2) includes a medium container (15) with a filling hole and a liquid material (16) located in the medium container (15).

3. The high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium according to claim 1, characterized in that: The floor layer (3) includes a bottom dielectric substrate (8) placed horizontally at the bottom and four coaxial connectors (7) located on the bottom dielectric substrate (8). The coaxial connectors (7) are respectively connected to the four corresponding grounded coplanar waveguide feed lines (10) through coaxial feed lines. The area of ​​the bottom dielectric substrate (8) is (48.0-70.0mm)*(48.0-70.0mm), and the thickness is 0.254-0.508mm.

4. The high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium according to claim 1, characterized in that: The decoupling structure (6) includes an annular neutralization line (13) printed on the lower surface of the top dielectric substrate (5) and a metal via (14) located inside the top dielectric substrate (5). The annular neutralization line (13) is connected to the midpoint of the long side of the non-radiative rectangular slot (11) of the radiating structure (4) through the metal via (14).

5. The high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium according to claim 2, characterized in that: The medium container (15) is a hollow cylinder with a bottom radius of 18.20-20.40 mm and a height of 4.80-7.60 mm. The container wall thickness of the medium container (15) is 0.80-1.20 mm. The height of the liquid material (16) is 0.52mm-3.80mm, the filling rate p is 0.13-0.95, and the liquid material (16) is ethanol.

6. The high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium according to claim 1, characterized in that: The overall profile height of the antenna is 5.80-8.60mm; the area of ​​the top dielectric substrate (5) is (42.0-48.0mm)*(42.0-48.0mm), the chamfer width is 9.50-12.50mm, and the thickness is 0.254-0.508mm.

7. The high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium according to claim 1, characterized in that: The rectangular slot (9) has a length of 9.0-12.0 mm and a width of 3.20-3.80 mm; the grounded coplanar waveguide feed (10) has a length of 11.50-14.50 mm and a width of 1.05-1.35 mm, and the center of the grounded coplanar waveguide feed (10) is 2.20-3.10 mm away from the opening of the rectangular slot (9); the non-radiative rectangular slot (11) has a length of 9.80-14.20 mm and a width of 4.60-6.10 mm; and the circular slot (12) has a radius of 14.20-16.80 mm.

8. A high-isolation reconfigurable four-port MIMO slot antenna based on a liquid medium according to claim 4, characterized in that: The inner ring radius of the annular neutralization line (13) is 10.20-13.40 mm, and the ring width of the annular neutralization line (13) is 0.40-0.80 mm; the radius of the metal through hole (14) is 0.25-0.50 mm.

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