Metamaterial antenna applied to Internet of Things communication and preparation method thereof

Abstract

The invention provides a metamaterial antenna applied to Internet of Things communication and a preparation method. According to the metamaterial antenna, a grounding layer is spin-coated on a first surface of a substrate layer; the second surface of the substrate layer is spin-coated with a metamaterial unit layer; the first surface is opposite to the second surface; the substrate layer is composed of polylactic acid, plant oil-based epoxy resin and a phase solvent; a feed layer is etched on the first surface of the grounding layer; the grounding layer is composed of copper particles. The first surface of the metamaterial unit layer is spin-coated with a matching layer; the metamaterial unit layer is composed of graphene nanopowder, a solvent and a dispersing agent; the first surface of the matching layer is spin-coated with a protective layer; the matching layer is composed of a polyimide solution; and the protective layer is formed by spin-coating a polyimide solution and an antistatic agent. According to the metamaterial antenna, a multi-layer composite structure is utilized, and the overall size of the metamaterial antenna is effectively reduced. And by adopting the biodegradable material, the preparation cost and the environmental influence are reduced.

Description

Technical Field

[0001] The present application relates to the field of Internet of Things communication technology, and in particular to a metamaterial antenna used in Internet of Things communication and a preparation method thereof. Background Art

[0002] Internet of Things (IoT) communication is a key technology for data transmission and information exchange between devices in the IoT. It supports efficient connectivity between devices, sensors, and platforms, enabling intelligent systems to function in diverse scenarios, such as smart homes, industrial automation, smart cities, and agricultural IoT. The fundamental requirements for IoT communication are low power consumption, low latency, a large number of connections, and diverse capabilities.

[0003] IoT communication antennas are key components used to transmit and receive wireless signals in IoT devices. Since IoT devices are typically compact and low-power, the antenna requirements are particularly stringent. However, traditional antennas still have certain limitations, hindering their ability to provide more efficient, flexible, and adaptable performance.

[0004] A metamaterial antenna is an antenna designed and manufactured using metamaterial technology. It achieves special manipulation of electromagnetic waves through artificially designed microstructures, thereby achieving performance that exceeds that of traditional antennas. Therefore, applying metamaterial antennas to IoT communications can overcome the limitations of traditional antennas and provide more efficient, flexible and adaptable performance.

[0005] At present, there are many types of traditional metamaterial antenna structures. However, due to the demand for miniaturization and lightweight in IoT communications, traditional metamaterial antenna structures have certain difficulties in miniaturization, which in turn has a certain impact on the preparation cost of metamaterial antenna structures. Summary of the Invention

[0006] In view of this, the purpose of this application is to propose a metamaterial antenna and a preparation method for Internet of Things communications. This metamaterial antenna and a preparation method for Internet of Things communications have the advantages of utilizing a multi-layer composite structure and being able to effectively reduce the overall size of the metamaterial antenna by stacking functional layers. It is suitable for space-constrained Internet of Things devices and solves the problems existing in the prior art.

[0007] Based on the above objectives, the present application provides a metamaterial antenna for Internet of Things communications, comprising: a protective layer, a matching layer, a metamaterial unit layer, a substrate layer, a ground layer, and a feeding layer; the feeding layer is coupled with the metamaterial unit layer for feeding;

[0008] The ground layer is spin-coated on the first surface of the substrate layer; the metamaterial unit layer is spin-coated on the second surface of the substrate layer; the first surface and the second surface are arranged opposite to each other; the substrate layer is composed of polylactic acid, vegetable oil-based epoxy resin and a compatibilizer;

[0009] The feed layer is etched on the first surface of the ground layer; the ground layer is composed of copper particles;

[0010] The matching layer is spin-coated on the first surface of the metamaterial unit layer; the metamaterial unit layer is composed of graphene nanopowder, solvent and dispersant;

[0011] A protective layer is spin-coated on the first surface of the matching layer; the matching layer is composed of a polyimide solution; and the protective layer is spin-coated with a polyimide solution and an antistatic agent.

[0012] Based on the same inventive concept, an embodiment of the present application further provides a method for preparing a metamaterial antenna for IoT communication, comprising:

[0013] Mixing polylactic acid, a vegetable oil-based epoxy resin, and a compatibilizer in a twin-screw extruder at 180° C. to 200° C. to obtain a substrate mixture; hot-pressing the substrate mixture in a hot press and cooling it to room temperature to obtain a substrate layer;

[0014] adding graphene nanopowder and a dispersant to a solvent, and sequentially performing ultrasonic treatment and filtering treatment to obtain a suspension; spin-coating the suspension on the second surface of the substrate layer to form a graphene film layer; performing a first heat treatment on the graphene film layer, and forming a metamaterial unit structure on the graphene film layer by photolithography to obtain a metamaterial unit layer;

[0015] Applying a polyamic acid solution to the first surface of the metamaterial unit layer by spin coating to perform a second heat treatment to obtain a matching layer;

[0016] Depositing metal copper particles on the first surface of the substrate layer by a laser direct writing method to obtain a grounding layer;

[0017] Coating photoresist on the first surface of the ground layer, and etching a microstrip line pattern using an etching solution to obtain a feed layer;

[0018] A polyimide solution and an antistatic agent are mixed to obtain a protective layer solution; the protective layer solution is applied to the first surface of the matching layer by a spin coating method and a third heat treatment is performed to obtain a protective layer.

[0019] In a possible implementation, the ratio of the polylactic acid, the plant oil-based epoxy resin and the phase solvent is: (7-7.5): (2.5-3): (0.25-0.45), and the phase solvent is a maleic anhydride grafted phase solvent.

[0020] In a possible implementation, the solvent is ethanol, the dispersant is polyvinyl pyrrolidone, the addition ratio of the graphene nanopowder is 0.5-2 wt%, and the addition ratio of the dispersant is 0.1 wt%.

[0021] In a possible implementation, the antistatic agent is single-walled carbon nanotubes, and the addition ratio of the antistatic agent is 0.1 to 0.8 wt %.

[0022] In a possible implementation, the ultrasonic treatment time is 30 to 50 minutes, and the ultrasonic treatment power is 200 to 300W.

[0023] In a possible implementation, the first heat treatment includes: performing heat treatment in an oven at a temperature of 150 to 250° C., and the time for the first heat treatment is 30 to 50 minutes.

[0024] In a possible implementation, the second heat treatment includes: heating to 80° C. for 30 minutes, heating to 180° C. for 40 minutes, and heating to 280° C. for 50 minutes.

[0025] In a possible implementation, the third heat treatment includes: heating to 80° C. for 30 minutes, heating to 180° C. for 40 minutes, and heating to 280° C. for 50 minutes.

[0026] In a possible implementation, the laser power of the laser direct writing method is 15W, and the scanning speed is 120mm / s.

[0027] As can be seen from the above, the metamaterial antenna and preparation method for Internet of Things communication provided by the present application include: a protective layer, a matching layer, a metamaterial unit layer, a substrate layer, a ground layer and a feed layer; the feed layer is coupled and fed with the metamaterial unit layer; the first surface of the substrate layer is spin-coated with the ground layer; the second surface of the substrate layer is spin-coated with the metamaterial unit layer; the first surface and the second surface are arranged opposite to each other; the substrate layer is composed of polylactic acid, vegetable oil-based epoxy resin and a compatibilizer; the first surface of the ground layer is etched with the feed layer; the ground layer is composed of copper particles; the first surface of the metamaterial unit layer is spin-coated with the matching layer; the metamaterial unit layer is composed of graphene nanopowder, solvent and dispersant; the first surface of the matching layer is spin-coated with a protective layer; the matching layer is composed of a polyimide solution; the protective layer is spin-coated with a polyimide solution and an antistatic agent. The present application utilizes a multi-layer composite structure and, by stacking functional layers, can effectively reduce the overall size of the metamaterial antenna, making it suitable for space-constrained IoT devices. At the same time, in the multi-layer composite structure provided by the present invention, the cooperation of the matching layer and the protective layer is provided to reduce signal reflection and improve the power transmission efficiency of the antenna. An antistatic agent is introduced into the protective layer to avoid electrostatic damage, improve the long-term reliability of the antenna, and adapt to complex electromagnetic environments. Furthermore, in the preparation process, the overall structure is mostly combined by spin coating, which is conducive to large-scale application. At the same time, biodegradable materials are used as the substrate layer, and graphene nanopowder is used to replace metal films such as copper and silver. Therefore, the present invention combines the concept of green environmental protection in the preparation process, thereby reducing preparation costs and environmental impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in this application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are merely embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 This is a schematic diagram of the structure of a metamaterial antenna applied to Internet of Things communications according to an embodiment of the present application;

[0030] Figure 2 This is a flow chart of a method for preparing a metamaterial antenna for IoT communication according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0032] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should have the usual meanings understood by people with ordinary skills in the field to which this application belongs. The "first", "second" and similar words used in the embodiments of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0033] As mentioned in the background technology section, traditional IoT communication antennas have certain performance limitations and cannot fully meet the stringent requirements of IoT devices for miniaturization, low power consumption, and high efficiency. They also have poor adaptability and are unable to flexibly respond to complex and diverse IoT application scenarios. Although metamaterial antennas achieve special manipulation of electromagnetic waves through artificially designed microstructures and have significant performance advantages, existing metamaterial antennas face technical bottlenecks in further miniaturization and are unable to meet the requirements of IoT devices for lightweight structures and compact size. In addition, the preparation cost of metamaterial antennas is constrained by miniaturization technology and can be high, which affects their widespread application and market promotion, making it difficult to fully unleash the potential of IoT communications for high efficiency, low power consumption, and a large number of connections.

[0034] Based on the above considerations, the embodiment of the present application proposes a metamaterial antenna for Internet of Things communication and a preparation method, including: a protective layer, a matching layer, a metamaterial unit layer, a substrate layer, a ground layer and a feed layer; the feed layer is coupled and fed with the metamaterial unit layer; the first surface of the substrate layer is spin-coated with the ground layer; the second surface of the substrate layer is spin-coated with the metamaterial unit layer; the first surface and the second surface are arranged opposite to each other; the substrate layer is composed of polylactic acid, vegetable oil-based epoxy resin and a compatibilizer; the first surface of the ground layer is etched with the feed layer; the ground layer is composed of copper particles; the first surface of the metamaterial unit layer is spin-coated with the matching layer; the metamaterial unit layer is composed of graphene nanopowder, solvent and dispersant; the first surface of the matching layer is spin-coated with a protective layer; the matching layer is composed of a polyimide solution; the protective layer is spin-coated with a polyimide solution and an antistatic agent. The present application utilizes a multi-layer composite structure and, by stacking functional layers, can effectively reduce the overall size of the metamaterial antenna, making it suitable for space-constrained IoT devices. At the same time, in the multi-layer composite structure provided by the present invention, the cooperation of the matching layer and the protective layer is provided to reduce signal reflection and improve the power transmission efficiency of the antenna. An antistatic agent is introduced into the protective layer to avoid electrostatic damage, improve the long-term reliability of the antenna, and adapt to complex electromagnetic environments. Furthermore, in the preparation process, the overall structure is mostly combined by spin coating, which is conducive to large-scale application. At the same time, biodegradable materials are used as the substrate layer, and graphene nanopowder is used to replace metal films such as copper and silver. Therefore, the present invention combines the concept of green environmental protection in the preparation process, thereby reducing preparation costs and environmental impact.

[0035] The technical solutions of the embodiments of the present application are described in detail below through specific examples.

[0036] refer to Figure 1 The metamaterial antenna for Internet of Things communication of the embodiment of the present application includes: a protective layer 1, a matching layer 2, a metamaterial unit layer 3, a substrate layer 4, a ground layer 5 and a feed layer 6; the feed layer 6 is coupled and fed with the metamaterial unit layer 3; the first surface of the substrate layer 4 is spin-coated with the ground layer 5; the second surface of the substrate layer 4 is spin-coated with the metamaterial unit layer 3; the first surface and the second surface are arranged opposite to each other; the substrate layer 4 is composed of polylactic acid, vegetable oil-based epoxy resin and a compatibilizer; the first surface of the ground layer 5 is etched with the feed layer 6; the ground layer 5 is composed of copper particles; the first surface of the metamaterial unit layer 3 is spin-coated with the matching layer 2; the metamaterial unit layer 3 is composed of graphene nanopowder, solvent and dispersant; the first surface of the matching layer 2 is spin-coated with the protective layer 1; the matching layer 2 is composed of a polyimide solution; the protective layer 1 is spin-coated with a polyimide solution and an antistatic agent.

[0037] The materials in the following examples were all purchased commercially; the plant oil-based epoxy resin was prepared from plant oils (soybean oil, rapeseed oil, linseed oil) by epoxidation reaction, and was a single-component epoxy resin; the polyamic acid solution was diluted with 20% (total solution) of NMP solvent; and room temperature was 25±5°C.

[0038] In this embodiment, according to Figure 1 As shown, this embodiment proposes a metamaterial antenna for Internet of Things communication, including a substrate layer 4, a metamaterial unit layer 3, a ground layer 5, a feed layer 6, a matching layer 2 and a protective layer 1. The back of the substrate layer 4 is spin-coated with a ground layer 5, the back of the ground layer 5 is etched with a feed layer 6, the surface of the metamaterial unit layer 3 is spin-coated with a matching layer 2, the surface of the matching layer 2 is spin-coated with a protective layer 1, and the feed layer 6 and the metamaterial unit layer 3 are fed by magnetic field coupling.

[0039] Substrate layer 4 is composed of polylactic acid, a plant oil-based epoxy resin, and a compatibilizer. Substrate layer 4 is the foundation of the metamaterial antenna and is made of a material with a low dielectric constant. This embodiment uses a mixture of polylactic acid and plant oil-based epoxy resin as the material for substrate layer 4. Polylactic acid is derived from plants (such as corn and sugarcane), while plant oil-based epoxy resin is derived from plant oils. Both are renewable resources. Polylactic acid can be degraded under certain conditions, making it environmentally friendly and reducing long-term ecological pollution caused by waste materials. Therefore, in this embodiment, the preparation of substrate layer 4 incorporates the concept of green environmental protection. The compatibilizer is a maleic anhydride-grafted compatibilizer.

[0040] Metamaterial unit layer 3 is composed of graphene nanopowder, a solvent, and a dispersant. Metamaterial unit layer 3 imparts unique electromagnetic properties to the antenna. In this embodiment, graphene nanopowder replaces metal films such as copper and silver. Graphene is derived from carbon-based materials and is environmentally friendly, while metal materials (such as copper and silver) can cause pollution during production and disposal. Graphene's raw materials are widely available (such as graphite ore and carbide), resulting in lower production costs and abundant resource reserves, meeting the needs of sustainable green and environmentally friendly development. The solvent is ethanol, and the dispersant is polyvinyl pyrrolidone.

[0041] The matching layer 2 is composed of a polyimide solution. The function of the matching layer 2 is to achieve impedance matching to improve the radiation efficiency of the antenna. In this embodiment, the matching layer 2 is prepared by spin coating a polyimide solution, which has the advantage of stable performance.

[0042] Protective layer 1 is composed of a spin-coated polyimide solution and an antistatic agent. Located at the outermost layer of the antenna, protective layer 1 primarily protects the internal structure from environmental influences. Therefore, this embodiment still utilizes the polyimide solution design and incorporates an antistatic agent. As a result, protective layer 1 in this embodiment can function as matching layer 2 to some extent while also providing protection. The antistatic agent is single-walled carbon nanotubes.

[0043] The grounding layer 5 is composed of copper particles and is located at the bottom of the antenna. It mainly plays a grounding role to ensure the normal operation of the antenna.

[0044] The feeding layer 6 is responsible for transmitting the signal to the radiation layer, thereby realizing the emission and reception of electromagnetic waves.

[0045] Based on the same inventive concept, corresponding to any of the above-mentioned embodiments and methods, the present application also provides a method for preparing a metamaterial antenna for use in Internet of Things communications.

[0046] refer to Figure 2 The method for preparing the metamaterial antenna for Internet of Things communication comprises:

[0047] Step S201, polylactic acid, a vegetable oil-based epoxy resin, and a compatibilizer are mixed in a twin-screw extruder at 180° C. to 200° C. to obtain a substrate mixture; the substrate mixture is hot-pressed in a hot press and cooled to room temperature to obtain a substrate layer;

[0048] Step S202: adding graphene nanopowder and a dispersant to a solvent, and sequentially performing ultrasonic treatment and filtration treatment to obtain a suspension; spin-coating the suspension on the second surface of the substrate layer to form a graphene thin film layer; performing a first heat treatment on the graphene thin film layer, and forming a metamaterial unit structure on the graphene thin film layer by photolithography to obtain a metamaterial unit layer;

[0049] Step S203, applying a polyamic acid solution to the first surface of the metamaterial unit layer by spin coating, and performing a second heat treatment to obtain a matching layer;

[0050] Step S204, depositing metal copper particles on the first surface of the substrate layer using a laser direct writing method to obtain a grounding layer;

[0051] Step S205, coating a photoresist on the first surface of the ground layer, and etching a microstrip line pattern using an etching solution to obtain a feed layer;

[0052] Step S206 , mixing the polyimide solution and the antistatic agent to obtain a protective layer solution; applying the protective layer solution to the first surface of the matching layer by spin coating and performing a third heat treatment to obtain a protective layer.

[0053] Regarding step S201 , in some embodiments, the ratio of the polylactic acid, the plant oil-based epoxy resin, and the phase solvent is: (7-7.5): (2.5-3): (0.25-0.45), and the phase solvent is a maleic anhydride grafted phase solvent.

[0054] In this embodiment, the preparation process of the substrate layer 4 is to prepare polylactic acid, vegetable oil-based epoxy resin and a phase solvent, and the weight ratio between polylactic acid, vegetable oil-based epoxy resin and the phase solvent is: 7:2.5:0.45, and then mix them in a twin-screw extruder at 180°C to obtain a substrate mixture. After the substrate mixture is extruded through the twin-screw extruder, it is immediately loaded into a mold and then hot-pressed using a hot press (pressure of 8 MPa) to ensure the uniformity and density of the substrate, and then cooled to room temperature to obtain the substrate layer 4.

[0055] Regarding step S202, in some embodiments, the solvent is ethanol, the dispersant is polyvinyl pyrrolidone, the addition ratio of the graphene nanopowder is 0.5-2 wt%, and the addition ratio of the dispersant is 0.1 wt%.

[0056] In some embodiments, the first heat treatment includes: performing heat treatment in an oven at a temperature of 150 to 250° C., and the time for the first heat treatment is 30 to 50 minutes.

[0057] In some embodiments, the ultrasonic treatment time is 30 to 50 minutes, and the ultrasonic treatment power is 200 to 300W.

[0058] In this embodiment, the spin coating process of the metamaterial unit layer 3 is as follows: prepare graphene nanopowder, solvent and dispersant, the graphene nanopowder is added in a ratio of 0.5wt% and the dispersant is added in a ratio of 0.1wt%, add the graphene nanopowder and dispersant (polyvinyl pyrrolidone) to the solvent (ethanol), and perform ultrasonic treatment and filtration treatment in sequence. Specifically, after adding the solvent, stir for 10 minutes, then perform ultrasonic treatment for 30 minutes, and the ultrasonic power is 300W. After ultrasonic treatment, filter to remove undispersed graphene or impurities to obtain a uniform suspension, and then use spin coating (spin coating speed: 2000 rpm, time 50s) to form a graphene thin film layer on the substrate layer 4 (natural drying after spin coating), and then perform a first heat treatment. The first heat treatment is specifically as follows: heat treatment in an oven at a temperature of 150°C for 50 minutes. After treatment, a metamaterial unit structure is formed on the graphene thin film layer by photolithography etching to obtain the metamaterial unit layer 3.

[0059] Regarding step S203, in some embodiments, the second heat treatment includes: heating to 80°C for 30 minutes, heating to 180°C for 40 minutes, and heating to 280°C for 50 minutes.

[0060] In this embodiment, a polyamic acid solution is prepared, and a matching layer 2 is formed on the surface of the metamaterial unit layer 3 by spin coating (spin coating speed 2000 rpm, time 50 s) (natural drying after spin coating), and then a second heat treatment is performed to obtain the matching layer 2.

[0061] Regarding step S204 and step S205, in some embodiments, the laser power of the laser direct writing method is 15W, and the scanning speed is 120mm / s.

[0062] In this embodiment, metal copper particles are prepared. The metal copper particles are used as conductive materials for the ground layer 5 and the feed layer 6. Correspondingly, corresponding photoresist and etching solution are also required. In this embodiment, the etching solution is ferric chloride solution. A laser direct writing method (laser power 15W, scanning speed 120mm / s) is used to form a ground layer 5 on the back of the substrate layer 4, that is, the metal copper particles are directly deposited on the back of the substrate layer 4 to form a continuous ground layer 5. Then, photoresist is coated on the surface of the ground layer 5. The coating method is spin coating (spin coating speed 2000rpm, time 50s), and the photoresist thickness is controlled to 8μm. Then, it is dried (drying for 8min at 80℃). Then, ultraviolet exposure technology is used to transfer the microstrip line pattern to the photoresist layer through a mask. The microstrip line pattern is etched out using an etching method using an etching solution. Specifically, a developing solution (2.38%) is used. The sample was treated with TMAH solution, and the microstrip line pattern area of ​​the copper layer was revealed after development. The sample was immersed in the etching solution, and the exposed copper area was etched to form a microstrip line pattern. The overall etching time was 10 minutes. After that, the sample was washed with pure water to remove the residual etching solution, and then acetone was used to remove the remaining photoresist to complete the preparation of the feed layer 6.

[0063] Regarding step S206 , in some embodiments, the antistatic agent is single-walled carbon nanotubes, and the addition ratio of the antistatic agent is 0.1-0.8 wt %.

[0064] In some embodiments, the third heat treatment includes: heating to 80° C. for 30 min, heating to 180° C. for 40 min, and heating to 280° C. for 50 min.

[0065] In this embodiment, a polyimide solution and an antistatic agent were prepared and mixed using a mixing device. The antistatic agent was added at a ratio of 0.1 wt % to obtain a protective layer 1 solution. The protective layer 1 solution was then applied to the matching layer 2 using a spin coating method (spin coating speed of 2000 rpm, time of 60 seconds) to obtain a protective layer 1. A third heat treatment was then performed to complete the spin coating of the protective layer 1. Both the second and third heat treatments employed a stepwise heating method, first to 80°C for 30 minutes, then to 180°C for 40 minutes, and finally to 280°C for 50 minutes.

[0066] In another feasible embodiment, the method for preparing the metamaterial antenna for IoT communication of the present application can also be implemented by the following steps:

[0067] Prepare polylactic acid, vegetable oil-based epoxy resin and a phase solvent, the weight ratio between polylactic acid, vegetable oil-based epoxy resin and the phase solvent is: 7.5:3:0.25, and then mix them in a twin-screw extruder at 200°C to obtain a substrate mixture. After the substrate mixture is extruded through the twin-screw extruder, it is immediately loaded into a mold and then hot-pressed using a hot press (pressure of 8 MPa) to ensure the uniformity and density of the substrate, and then cooled to room temperature to obtain a substrate layer 4.

[0068] Prepare graphene nanopowder, solvent and dispersant, with the graphene nanopowder added in a ratio of 2wt% and the dispersant added in a ratio of 0.1wt%. Add the graphene nanopowder and dispersant (polyvinyl pyrrolidone) to the solvent (ethanol), and perform ultrasonic treatment and filtration treatment in sequence. Specifically, after adding the solvent, stir for 10 minutes, then perform ultrasonic treatment for 50 minutes, and the ultrasonic power is 200W. After ultrasonic treatment, filter to remove undispersed graphene or impurities to obtain a uniform suspension, and then use spin coating (spin coating speed: 2000rpm, time 50s) to form a graphene thin film layer on the substrate layer 4 (natural drying after spin coating), and then perform a first heat treatment. The specific method of the first heat treatment is: heat treatment in an oven at a temperature of 250°C for 30 minutes. After treatment, use a photolithography etching method to form a metamaterial unit structure on the graphene thin film layer to obtain a metamaterial unit layer 3.

[0069] A polyamic acid solution was prepared, and a matching layer 2 was formed on the surface of the metamaterial unit layer 3 by spin coating (spin coating speed 2000 rpm, time 50 s) (natural drying after spin coating), and then a second heat treatment was performed to obtain the matching layer 2.

[0070] Prepare metal copper particles. The metal copper particles are used as conductive materials for the ground layer 5 and the feed layer 6. Correspondingly, corresponding photoresist and etching solution need to be prepared. In this embodiment, the etching solution is a ferric chloride solution. A laser direct writing method (laser power 15W, scanning speed 120mm / s) is used to form a ground layer 5 on the back of the substrate layer 4. That is, the metal copper particles are directly deposited on the back of the substrate layer 4 to form a continuous ground layer 5. Then, photoresist is coated on the surface of the ground layer 5. The coating method is spin coating (spin coating speed 2000rpm, time 50s), and the photoresist thickness is controlled to 8μm. Then, it is dried (at 80℃, dried for 8min). Then, ultraviolet exposure technology is used to transfer the microstrip line pattern to the photoresist layer through a mask. The microstrip line pattern is etched out using an etching method using an etching solution. Specifically, a developing solution (2.38%) is used. The sample was treated with TMAH solution, and the microstrip line pattern area of ​​the copper layer was revealed after development. The sample was immersed in the etching solution, and the exposed copper area was etched to form a microstrip line pattern. The overall etching time was 10 minutes. After that, the sample was washed with pure water to remove the residual etching solution, and then acetone was used to remove the remaining photoresist to complete the preparation of the feed layer 6.

[0071] A polyimide solution and an antistatic agent were prepared and mixed using a mixing device at a ratio of 0.8 wt% to obtain a protective layer 1 solution. The protective layer 1 solution was then applied to the matching layer 2 using spin coating (2000 rpm, 60 seconds) to obtain a protective layer 1. A third heat treatment was then performed to complete the spin coating of the protective layer 1. Both the second and third heat treatments employed a stepwise heating method, first to 80°C for 30 minutes, then to 180°C for 40 minutes, and finally to 280°C for 50 minutes.

[0072] It can be seen from the above embodiments that the preparation method of the metamaterial antenna for Internet of Things communication described in the embodiments of the present application is as follows: polylactic acid, vegetable oil-based epoxy resin and a compatibilizer are mixed at 180°C to 200°C in a twin-screw extruder to obtain a substrate mixture; the substrate mixture is hot-pressed by a hot press and cooled to room temperature to obtain a substrate layer; graphene nanopowder and a dispersant are added to the solvent, and ultrasonic treatment and filtration treatment are performed in sequence to obtain a suspension; the suspension is spin-coated on the second surface of the substrate layer to form a graphene film layer; the graphene film layer is subjected to a first heat treatment, and the graphene film layer is etched by photolithography. The metamaterial unit structure is formed on the graphene film layer by etching to obtain a metamaterial unit layer; a polyamide acid solution is spin-coated on the first surface of the metamaterial unit layer and subjected to a second heat treatment to obtain a matching layer; metal copper particles are deposited on the first surface of the substrate layer by laser direct writing to obtain a grounding layer; a photoresist is coated on the first surface of the grounding layer and a microstrip line pattern is etched using an etching solution to obtain a feeding layer; a polyimide solution and an antistatic agent are mixed to obtain a protective layer solution; the protective layer solution is applied to the first surface of the matching layer by spin coating and subjected to a third heat treatment to obtain a protective layer. The embodiments of the present application provide significant technical effects for the development of metamaterial antennas for Internet of Things communications through careful material selection, ratio optimization and process control. The use of polylactic acid, vegetable oil-based epoxy resin and compatibilizer as substrate materials not only ensures the uniformity and density of the substrate, but also achieves lightweight and environmentally friendly characteristics, meeting the requirements of Internet of Things devices for miniaturized antenna size and lightweight. By using ultrasonic dispersion, spin coating, and photolithography in the preparation of graphene as the core functional layer, a metamaterial unit layer with high conductivity and low loss characteristics was successfully constructed, thereby greatly improving the electromagnetic performance of the antenna, including signal propagation efficiency, gain, and sensitivity. Furthermore, a multi-layer preparation structure was adopted, in which the matching layer improved the transmission and reflection characteristics of electromagnetic waves, and the ground layer and feed layer formed a high-precision conductive structure through laser direct writing and etching processes, providing technical support for reducing manufacturing complexity and improving conductive efficiency. The methods used in the entire preparation process, such as spin coating, heat treatment, and laser direct writing, are mature and easy to industrialize, significantly reducing production costs. At the same time, the process parameters can be flexibly adjusted to adapt to different application requirements, with excellent flexibility and adaptability. In addition, the introduction of a protective layer using a polyimide solution and an antistatic agent composite enhances the environmental adaptability and long-term durability of the antenna, effectively resisting electromagnetic interference from the external environment, and extending the service life of the antenna. The overall approach has significant advantages in terms of environmentally friendly and economical material selection, efficient and simple preparation process, and strong controllability of process parameters. It lays a technical foundation for promoting the widespread and popularization of metamaterial antennas with superior performance and controllable costs in IoT communication applications, and is an important innovation and breakthrough in traditional antenna development.

[0073] It should be noted that the method of the embodiment of the present application can be performed by a single device, such as a computer or server. The method of this embodiment can also be applied in a distributed scenario and performed by multiple devices working together. In such a distributed scenario, one of the multiple devices may only perform one or more steps of the method of the embodiment of the present application, and the multiple devices will interact with each other to complete the method.

[0074] It should be noted that the above description is limited to some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in an order different from that described in the above embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0075] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application (including the claims) is limited to these examples. Within the scope of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0076] The embodiments of the present application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of this application.

Claims

1. A metamaterial antenna for Internet of Things communications, characterized in that: include: Protection layer, matching layer, metamaterial unit layer, substrate layer, ground layer and feed layer; The feeding layer is coupled with the metamaterial unit layer for feeding; The ground layer is spin-coated on the first surface of the substrate layer; the metamaterial unit layer is spin-coated on the second surface of the substrate layer; the first surface and the second surface are arranged opposite to each other; the substrate layer is composed of polylactic acid, vegetable oil-based epoxy resin and a compatibilizer; The feed layer is etched on the first surface of the ground layer; the ground layer is composed of copper particles; The matching layer is spin-coated on the first surface of the metamaterial unit layer; the metamaterial unit layer is composed of graphene nanopowder, solvent and dispersant; A protective layer is spin-coated on the first surface of the matching layer; the matching layer is composed of a polyimide solution; and the protective layer is spin-coated with a polyimide solution and an antistatic agent.

2. A method for preparing a metamaterial antenna for Internet of Things communication according to claim 1, characterized in that: include: Mixing polylactic acid, a vegetable oil-based epoxy resin, and a compatibilizer in a twin-screw extruder at 180° C. to 200° C. to obtain a substrate mixture; hot-pressing the substrate mixture in a hot press and cooling it to room temperature to obtain a substrate layer; adding graphene nanopowder and a dispersant to a solvent, and sequentially performing ultrasonic treatment and filtering treatment to obtain a suspension; spin-coating the suspension on the second surface of the substrate layer to form a graphene film layer; performing a first heat treatment on the graphene film layer, and forming a metamaterial unit structure on the graphene film layer by photolithography to obtain a metamaterial unit layer; Applying a polyamic acid solution to the first surface of the metamaterial unit layer by spin coating to perform a second heat treatment to obtain a matching layer; Depositing metal copper particles on the first surface of the substrate layer by a laser direct writing method to obtain a grounding layer; Coating photoresist on the first surface of the ground layer, and etching a microstrip line pattern using an etching solution to obtain a feed layer; Mixing a polyimide solution and an antistatic agent to obtain a protective layer solution; The protective layer solution is coated on the first surface of the matching layer by a spin coating method and then subjected to a third heat treatment to obtain a protective layer.

3. The method according to claim 2, characterized in that The ratio of the polylactic acid, the plant oil-based epoxy resin and the phase solvent is: (7-7.5): (2.5-3): (0.25-0.45), and the phase solvent is a maleic anhydride grafted phase solvent.

4. The method according to claim 2, characterized in that The solvent is ethanol, the dispersant is polyvinyl pyrrolidone, the addition ratio of the graphene nanopowder is 0.5-2 wt%, and the addition ratio of the dispersant is 0.1 wt%.

5. The method according to claim 2, characterized in that The antistatic agent is single-walled carbon nanotubes, and the addition ratio of the antistatic agent is 0.1-0.8 wt %.

6. The method according to claim 2, characterized in that The ultrasonic treatment time is 30 to 50 minutes, and the ultrasonic treatment power is 200 to 300W.

7. The method according to claim 2, characterized in that The first heat treatment includes: performing heat treatment in an oven at a temperature of 150 to 250° C., and the time for the first heat treatment is 30 to 50 minutes.

8. The method according to claim 2, characterized in that The second heat treatment includes: heating to 80° C. for 30 minutes, heating to 180° C. for 40 minutes, and heating to 280° C. for 50 minutes.

9. The method according to claim 2, characterized in that The third heat treatment includes: heating to 80° C. for 30 minutes, heating to 180° C. for 40 minutes, and heating to 280° C. for 50 minutes.

10. The method according to claim 2, characterized in that The laser power of the laser direct writing method is 15W, and the scanning speed is 120mm / s.

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