Self-decoupling metamaterial antenna array realized based on substrate punching

Abstract

The invention discloses a self-decoupling metamaterial antenna array realized based on substrate punching. The self-decoupling metamaterial antenna array comprises at least two metamaterial antenna units, each metamaterial antenna unit comprises a radiation unit and a feed unit, the radiation unit comprises a middle-layer substrate and a plurality of metallized through holes which are arranged on a top-layer dielectric substrate and are periodically distributed, and the two radiation units of the adjacent metamaterial antenna units share the metallized through hole located at the junction; the feed unit comprises a microstrip line arranged on the lower surface of the bottom layer dielectric substrate, a metal ground plane is arranged on the upper surface of the bottom layer dielectric substrate, and a gap used for coupling feed is formed in the metal ground plane. On the basis of not introducing additional decoupling circuits or decoupling elements, the isolation degree of adjacent units is improved, a good decoupling function is obtained, meanwhile, the array structure is simple and easy to integrate, and the millimeter wave multi-input and multi-output wireless communication system has potential application prospects.

Description

Technical Field

[0001] The present invention relates to the field of mobile communication antennas, and particularly to a self-decoupling antenna array for a metamaterial antenna achieved by punching holes in a substrate. Background Art

[0002] In recent years, with the sharp increase in data transmission requirements, the millimeter-wave (mm-Wave) spectrum has gradually become a key component of the fifth-generation (5G) mobile communication system. However, the millimeter-wave band faces significant spatial loss and blocking problems, resulting in a substantial decrease in the signal-to-noise ratio. Multiple-input multiple-output (MIMO) technology enhances the signal-to-noise ratio by utilizing spatial diversity, improving the transmission rate without consuming additional spectrum resources, thereby greatly enhancing the channel capacity of the communication system. Therefore, combining millimeter-wave and MIMO technologies has become one of the key trends in promoting 5G communication development. Nevertheless, when two or more antennas are closely arranged, mutual coupling inevitably occurs, which may weaken the performance of the antennas and even the entire system. In view of this, studying how to effectively reduce the mutual coupling between millimeter-wave antennas is particularly important and practically significant for improving system efficiency.

[0003] In the past decade, scholars have developed various decoupling means. The most common decoupling techniques can be classified into the following three categories. The first category of decoupling technique is to block the propagation of the coupling field through a decoupling structure, usually achieved by using metamaterials, defected ground planes, resonator decoupling structures. The second category is to introduce additional coupling paths to cancel the original coupling, such as neutralization lines, decoupling surfaces and other decoupling techniques. The third category is to achieve self-decoupling without introducing additional decoupling structures by utilizing the characteristics or operating modes of the antennas themselves.

[0004] As a type of metamaterial antenna, the current research on the decoupling technology of metasurface antennas mainly focuses on the microwave band. For example, in the article "Self-Decoupled Multiantennas With Coupling Modes Identification and Suppression", grooves are etched on the metasurface antenna to suppress the high-coupling characteristic modes to improve isolation. However, its bandwidth is limited, only 9%, and the broadband characteristics of the metasurface antenna are not fully utilized. In the article "Dual-Band Metasurface-Based Closely Packed Antennas by Controlling Surface Wave Propagation", a method of loading metal posts and side patches is proposed to directly suppress the propagation of surface waves and achieve good isolation. However, this method cannot solve the coupling problem of multi-element antennas. In "High Isolation H-Plane Placed Metasurface MIMO Antenna Using Characteristic Field Cancelation", metal vias are used to control the superposition electric field intensity to achieve good decoupling effects, but the distance between the two antennas is greater than 0.8λ.

[0005] Due to its characteristics such as wide bandwidth, stable gain, and easy excitation, the metasurface antenna has become an ideal candidate antenna in millimeter-wave systems. However, most of the existing decoupling technologies can only provide narrowband decoupling effects. In addition, although some decoupling methods perform well in the microwave band, due to the limitations of processing technology, these methods are not ideal for direct application in the millimeter-wave band. So far, the research on the decoupling of metasurface antenna arrays in the millimeter-wave band is still blank. Therefore, it is particularly important to develop a simple and broadband millimeter-wave antenna decoupling technology. Summary of the Invention

[0006] To achieve the above research goals, the purpose of the present invention is to provide a self-decoupling antenna array of metamaterial antennas based on substrate drilling. The antenna structure is relatively simple, has good decoupling effects, and the number of units can be extended to multi-element antenna decoupling.

[0007] To achieve the purpose of the present invention, a self-decoupling metamaterial antenna array based on substrate drilling provided by the present invention includes at least two metamaterial antenna units;

[0008] Each metamaterial antenna unit includes a radiation unit and a feeding unit. The radiation unit includes an intermediate layer substrate and a plurality of metallized vias arranged periodically on the top layer dielectric substrate, and two radiation units of adjacent metamaterial antenna units share the metallized via located at the junction; the feeding unit includes a microstrip line disposed on the lower surface of the bottom layer dielectric substrate, and a metal ground plane is provided on the upper surface of the bottom layer dielectric substrate, and a slot for coupled feeding is formed on the metal ground plane.

[0009] Further, the shared metallized via between two radiation units forms a shared radiator structure. By using the shared metallized via between two radiation units as the shared radiator of the two, the overall size of the antenna in the y direction can be reduced.

[0010] Further, the decoupling effect is adjusted by changing any one or more of the size of the metallized via, the arrangement of the metallized via, the number of the metallized via, and the number of the shared metallized via.

[0011] Further, an air medium is introduced on the intermediate layer substrate to broaden the isolation bandwidth. Introducing the air medium helps to reduce the dielectric constant of the intermediate layer substrate, thereby effectively expanding the decoupling bandwidth.

[0012] Further, the way to introduce the air medium is to set air vias on the intermediate layer substrate.

[0013] Further, the air vias are located between two metamaterial antenna units.

[0014] Further, the way to introduce the air medium can also be to set a notch on the intermediate layer substrate.

[0015] Further, the notch is located between two metamaterial antenna units.

[0016] Further, the slot is an H-shaped slot. Using the H-shaped slot can optimize the antenna input matching and impedance matching levels.

[0017] Further, due to the periodically arranged metallized vias and two radiation units sharing the metallized via located at the junction, the amplitudes of the coupled fields at the coupled feeding positions of the coupled antennas are equal but the phases are opposite, which prompts the currents to cancel each other at this position, thereby forming a weak current region and realizing the decoupling of the antenna array.

[0018] Further, the basic radiation unit of the antenna is formed by drilling metallized vias on the top layer dielectric substrate, and the arrangement of the metallized vias is a quasi-regular hexagonal structure of 2×4×5×4×2, and air vias are provided on both sides of the center position of the shared metallized via on the intermediate layer substrate.

[0019] Furthermore, on the intermediate substrate and between the two antenna elements, two columns of five rows of a total of ten air holes are symmetrically distributed, and the air holes will broaden the decoupling bandwidth problem of the antenna.

[0020] Compared with the existing technology, the beneficial effects and advantages of the present invention are as follows:

[0021] The present invention introduces an innovative self-decoupling technology, which is specifically designed for metamaterial antennas in the form of substrate drilling, and is applied to the millimeter-wave communication field. This technology forms metal columns by drilling periodically arranged metallized vias on the substrate to replace the metal sheets of traditional metasurface antennas, and adjacent metamaterial antenna elements share the metallized vias located at the junction, which can effectively regulate the coupling field distribution between adjacent antennas. Utilizing the characteristics that the current field amplitudes at the feeding points of adjacent coupled antennas are equal but the phases are opposite, a weak current region is formed in the coupling region, thereby improving the isolation of the antenna array. This method does not require additional decoupling circuits or components, simplifying the overall structure. Description of the Drawings

[0022] Figure 1 It is a three-dimensional structural schematic diagram of a self-decoupling metamaterial antenna array implemented based on substrate drilling provided by an embodiment of the present invention;

[0023] Figure 2 It is a top view of the top-layer drilled dielectric surface in an embodiment of the present invention;

[0024] Figure 3 It is a simulation diagram of the reflection coefficient of an embodiment of the present invention;

[0025] Figure 4 It is a simulation diagram of the gain of an embodiment of the present invention;

[0026] Figures 5a to 5c It is the radiation pattern of the first input port at each resonance point in an embodiment of the present invention, Figures 5a to 5c successively being the radiation patterns at 28 GHz, 32 GHz, and 36 GHz.

[0027] Figure 6 It is a schematic diagram of the distribution of metallized vias with different numbers and arrangements in an embodiment of the present invention.

[0028] Figure 7 It is a schematic diagram of opening a notch on the intermediate-layer substrate in an embodiment of the present invention. Detailed Embodiment

[0029] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0030] In the description of the present invention, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc., it is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0031] In the description of the present invention, the meaning of several is one or more, the meaning of multiple is more than two. Understandings such as greater than, less than, exceeding, etc. do not include the present number, and understandings such as above, below, within, etc. include the present number. If the first and second are described only for the purpose of distinguishing technical features, they should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or the sequence relationship of the indicated technical features.

[0032] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installation, connection, etc. should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0033] A self-decoupling metamaterial antenna array realized by punching holes in a substrate, comprising at least two metamaterial antenna units;

[0034] Each metamaterial antenna unit includes a radiation unit and a feeding unit. The radiation unit includes an intermediate layer substrate and a plurality of metallized vias arranged periodically on the top layer dielectric substrate, and two radiation units of adjacent metamaterial antenna units share the metallized via at the junction. The shared metallized via between the two radiation units forms a shared radiator structure; the feeding unit includes a microstrip line disposed on the lower surface of the bottom layer dielectric substrate, and a metal ground plane is provided on the upper surface of the bottom layer dielectric substrate. A slot for coupling feeding is opened on the metal ground plane, and the slot is an H-shaped slot.

[0035] Among them, the decoupling effect is adjusted by changing any one or more of the size of the metallized via, the arrangement mode of the metallized via, the number of the metallized vias, and the number of the shared metallized vias.

[0036] Among them, an air medium can be introduced on the intermediate layer substrate to broaden the isolation bandwidth. Preferably, the way to introduce the air medium is to set air vias on the intermediate layer substrate, and the air vias are located between two metamaterial antenna units; or, the way to introduce the air medium is to set a notch on the intermediate layer substrate, and the notch is located between two metamaterial antenna units.

[0037] By drilling metallized vias in the substrate and using the metallized vias instead of traditional metal sheets as radiators, combined with the arrangement of the metallized vias and the design of sharing radiators, the coupling field amplitudes at the feeding positions of the coupled antennas are made equal but opposite in phase, prompting the current to cancel out at this position, thereby forming a weak current region and achieving decoupling of the antenna array.

[0038] In the embodiments of the present invention, in order to make the metamaterial antenna unit resonate in the required frequency band and form a weak field region at the feeding position near the coupled unit to achieve port decoupling, the metallized vias as radiators can adopt a quasi - hexagonal arrangement of 2×4×5×4×2. Four metallized vias at the upper, lower, left, and right of the junction are shared by adjacent metamaterial antenna units. However, this decoupling method is not limited to this specific structure. According to the required resonant frequency band, the decoupling effect can be adjusted by flexibly adjusting any one or more parameters such as the size of each metallized via, the arrangement of the metallized vias, the number of shared metallized vias, and the spacing between the metallized vias, with strong flexibility.

[0039] At the position between two antenna units on the middle - layer substrate, two columns of five rows, a total of ten air vias are symmetrically distributed. The air vias will broaden the decoupling bandwidth problem of the antenna. The air vias do not have to be arranged in two columns of five rows and can be adjusted accordingly according to the influence of the air vias on the decoupling bandwidth.

[0040] The following combines Figures 1 - 7 to explain in detail the structure and performance of the self - decoupling antenna array of the above - mentioned metamaterial antenna based on substrate drilling.

[0041] Refer to Figure 1 and Figure 2, A self - decoupling metamaterial antenna array realized by substrate drilling provided by an embodiment of the present invention includes at least two metamaterial antenna units, and each metamaterial antenna unit includes a radiation unit and a feeding unit part. Among them, the dielectric substrate where the radiation unit is located includes two layers of dielectric substrates, namely a top - layer dielectric substrate 11 and an intermediate - layer substrate 12. In some embodiments of the present invention, the top - layer dielectric substrate 11 and the intermediate - layer substrate 12 are a combination of two Rogers5880 high - frequency plates with the same thickness. The dielectric constant of the dielectric substrate is 2.2, the size is 12mm×25mm, and the thickness is 0.508mm. The radiation unit includes the intermediate - layer substrate 12 and metallized vias (21, 22, 3) arranged in a 2×4×5×4×2 - like regular - hexagon pattern on the top - layer dielectric substrate 11. And the two radiation units share four metallized vias 3 at the junction to form a shared radiator structure, and the size of each metallized via is the same. And ten air vias 4 are drilled in two rows and five columns below and between the two radiation units on the intermediate - layer substrate 12 and fed by a microstrip line through a slot. That is, 21, 3, 61 and 71 form a metamaterial antenna unit, 22, 3, 62 and 72 form another metamaterial antenna unit, and the two share the metallized via 3 at the junction; the feeding unit is printed on the lower surface of the bottom - layer dielectric substrate 13 (feeding substrate). The feeding unit includes a first microstrip line 71 or a second microstrip line 72 printed on the lower surface of the bottom - layer dielectric substrate 13, and metal ground planes 5 are provided on the lower surface of the intermediate - layer substrate 12 and the upper surface of the bottom - layer dielectric substrate 13, and slots (61, 62) for coupled feeding are etched on the two metal ground planes 5. In other embodiments, the number and arrangement of the metallized vias can also adopt other methods, such as Figure 6 As shown, 4 different arrangement methods are shown in the figure, and the shared metallized vias are outlined by a dashed line box in the figure. The method of introducing air medium can also adopt other methods, such as Figure 7 As shown, a notch 8 is opened on the intermediate - layer substrate 12.

[0042] In some embodiments of the present invention, the diameter of the metallized vias is 1.4mm, and the distance between adjacent metallized vias is 0.2mm.

[0043] In some embodiments of the present invention, the diameter of the air vias 4 is 1.6mm, and the distance between adjacent air vias 4 is 0.2mm.

[0044] In some embodiments of the present invention, the widths of the first microstrip line 71 and the second microstrip line 72 are both 0.74mm. The center - to - center distance d between the two metamaterial antenna units is 5.1mm, which is approximately 0.537 times the free - space wavelength at the center frequency.

[0045] In some embodiments of the present invention, the bottom dielectric substrate 13 is a thin Rogers 5880 dielectric substrate with a dielectric constant of 2.2 and a height of 0.254 mm.

[0046] In some embodiments of the present invention, the gap is an H-shaped gap.

[0047] In order to further illustrate the good performance of the self-decoupling antenna array of the metamaterial antenna based on the substrate perforation provided by the present invention, the electromagnetic simulation software HFSS is used to model and simulate this embodiment. Figure 3 -5 is the simulation result of the H-plane coupled broadband millimeter-wave substrate perforated metamaterial antenna.

[0048] like Figure 3 As shown, the S parameter simulation result diagram of this embodiment is given. The bandwidth of the self-decoupling antenna array with a reflection coefficient less than -10dB is 26.42GHz-36.06GHz, the absolute bandwidth is 9.64GHz, and the relative working frequency bandwidth is about 30%. Two resonant frequencies are generated at 28.9GHz and 34.7GHz, and the two resonant frequencies work together to produce good broadband performance. At the same time, the bandwidth of the self-decoupling antenna array with an isolation less than -20dB and a gain drop of <3dB is 27.94GHz-35.16GHz, the absolute bandwidth is 7.22GHz, the relative working frequency bandwidth is about 23%, and the maximum isolation value is nearly 50dB.

[0049] like Figure 4 As shown, a gain simulation result diagram of this embodiment is given. The maximum gain of the antenna is 8.11dBi, and the gain fluctuation within the impedance bandwidth of 27.94GHz-35.16GHz is less than 3dBi.

[0050] Figures 5a to 5c The first input port ( Figure 1 The radiation pattern of the structure port1) shown in the figure at 28GHz, 32GHz, and 36GHz. It is observed that the cross polarization is low in the entire passband and the radiation performance is good. Among them, X-pol is cross polarization and Co-pol is main polarization.

[0051] Experimental results show that the antenna array of the embodiment of the present invention achieves 23% S11<-10dB impedance bandwidth and S21<-20dB decoupling bandwidth, significantly reducing the maximum coupling of the H-plane to -50dB, and the antenna shows a maximum gain of about 8.1dB in the working frequency band. This achievement provides an efficient and concise solution for improving the performance of millimeter wave communication systems.

[0052] An embodiment of the present invention proposes a self - decoupling technique for a metamaterial antenna suitable for substrate drilling and applies it to millimeter - wave communication. The traditional two - dimensional planar metasurface antenna is extended to a three - dimensional structure. By introducing metallized vias in the dielectric substrate to replace the original method of etching metal sheets, and through the arrangement of these metallized vias and the way of sharing radiators, using the characteristics that the field amplitudes at the feeding position of the adjacent - coupling current field are equal but the phases are opposite, a weak - current region is formed, thereby improving the isolation of the antenna array. In addition, drilling air vias 4 in the middle - layer substrate 13 further broadens the isolation bandwidth of the array, and the maximum coupling in the H - plane can be reduced to about - 50 dB within a bandwidth of 23%.

[0053] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A self - decoupling metamaterial antenna array realized based on substrate punching, characterized in that, Comprising at least two metamaterial antenna units; Each metamaterial antenna unit includes a radiation unit and a feeding unit. The radiation unit includes an intermediate layer substrate and a plurality of metallized vias arranged periodically on the top layer dielectric substrate, and two radiation units of adjacent metamaterial antenna units share the metallized via located at the junction; The feeding unit includes a microstrip line disposed on the lower surface of the bottom layer dielectric substrate, and a metal ground plane is provided on the upper surface of the bottom layer dielectric substrate, and a slot for coupled feeding is formed on the metal ground plane.

2. The self-decoupling metamaterial antenna array implemented based on substrate punching according to claim 1, wherein The metallized vias shared between two radiation units form a shared radiator structure.

3. The self - decoupling metamaterial antenna array implemented based on substrate punching according to claim 1, characterized in that, The decoupling effect is adjusted by changing any one or more of the size of the metallized vias, the spacing between the metallized vias, the arrangement mode of the metallized vias, the number of the metallized vias, and the number of the shared metallized vias.

4. The self-decoupling metamaterial antenna array implemented based on substrate punching according to claim 1, wherein, An air medium is introduced on the intermediate layer substrate to broaden the isolation bandwidth.

5. The self-decoupling metamaterial antenna array implemented based on substrate punching according to claim 4, characterized in that, The way to introduce the air medium is to provide air vias on the intermediate layer substrate.

6. The self-decoupling metamaterial antenna array implemented based on substrate punching according to claim 5, wherein, The air vias are located between two metamaterial antenna units.

7. The self - decoupling metamaterial antenna array implemented based on substrate punching according to claim 4, wherein, The way to introduce the air medium can also be to provide a notch on the intermediate layer substrate.

8. The self - decoupling metamaterial antenna array implemented based on substrate punching according to claim 7, characterized in that, The notch is located between two metamaterial antenna units.

9. The self-decoupling metamaterial antenna array implemented based on substrate punching according to claim 1, wherein, The slot is an H-shaped slot.

10. A self-decoupling metamaterial antenna array realized based on substrate punching according to any one of claims 1-9, characterized in that Due to the periodically arranged metallized vias and two radiation units sharing the metallized via located at the junction, the current cancellation occurs at the coupled antenna feeding point to achieve the decoupling of the antenna array.

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