Electromagnetic wave absorber

Abstract

The electromagnetic wave absorber comprises a matching impedance layer, a temperature control phase change resonance layer, a magnetic control phase change regulation and control layer and a metal reflection layer which are sequentially stacked, wherein the temperature-control phase-change resonance layer comprises a base body layer, a plurality of temperature-control phase-change units which are periodically arranged on the base body layer, and a heating layer which is attached to the surface of one side of the base body layer; the heating layer is used for adjusting the temperature of the temperature control phase change unit, so that the conductivity of the temperature control phase change resonance layer is changed; the magnetic control phase change regulation and control layer comprises a magnetic control coil and magnetic control phase change units which are periodically arranged; the magnetic control coil is used for applying magnetic fields with different sizes to the magnetic control phase change unit, so that the magnetic conductivity of the magnetic control phase change material structure is changed; and the arrangement period sizes of the temperature control phase change units and the magnetic control phase change units are between nanometer magnitude and millimeter magnitude. According to the electromagnetic wave absorber, the wave absorbing frequency capable of absorbing waves can be switched and adjusted within a larger range, and therefore the requirements of various different application scenes can be better met.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave technology, and in particular to an electromagnetic wave absorber. Background Technology

[0002] Electromagnetic wave absorbers play an indispensable role in fields such as military stealth, electromagnetic compatibility, and microwave protection. With the widespread application of electromagnetic wave absorbers, the frequency band and intensity of the electromagnetic waves they can absorb often need to be dynamically adjusted according to changes in environment or mission requirements. For example, aircraft need to cope with radar waves of different frequencies at different flight stages, placing an urgent demand on absorbers that are "real-time adjustable and intelligently responsive."

[0003] Therefore, how to maximize the dynamic control range of electromagnetic wave absorber absorption performance has become an important research direction and technical challenge in this field. Summary of the Invention

[0004] The purpose of this invention is to provide an electromagnetic absorber that can dynamically adjust the absorption frequency over a wide frequency band, which is beneficial for meeting the application needs of different scenarios.

[0005] To solve the above-mentioned technical problems, the present invention provides an electromagnetic absorber, comprising a matching impedance layer, a temperature-controlled phase change resonant layer, a magnetically controlled phase change modulation layer, and a metal reflective layer stacked sequentially.

[0006] The temperature-controlled phase change resonant layer includes a substrate layer and a plurality of temperature-controlled phase change units arranged periodically on the substrate layer, as well as a heating layer disposed on one side surface of the substrate layer; the heating layer is used to adjust the temperature of the temperature-controlled phase change units so as to change the conductivity of the temperature-controlled phase change resonant layer.

[0007] The magnetically controlled phase change control layer includes a magnetically controlled coil and magnetically controlled phase change units arranged in a periodic manner; the magnetically controlled coil is used to apply magnetic fields of different magnitudes to the magnetically controlled phase change units to cause the magnetic permeability of the magnetically controlled phase change material structure to change.

[0008] The arrangement period of both the temperature-controlled phase change unit and the magneto-controlled phase change unit is between the nanometer and millimeter scales.

[0009] In one optional embodiment of this application, the temperature-controlled phase change unit includes a rare earth nickelate unit, a vanadium dioxide unit, or a modified vanadium dioxide unit; wherein the modified vanadium dioxide unit is a vanadium dioxide unit doped with any one of tungsten, fluorine, aluminum, or titanium.

[0010] In one optional embodiment of this application, the substrate layer includes a polyimide layer, an epoxy resin layer, a polydimethylsiloxane layer, a polyurethane polymer layer, or a ceramic layer.

[0011] In one optional embodiment of this application, the heating layer includes an indium tin oxide film, a fluorine-doped tin oxide film, a silver nanowire mesh film, a graphene film, or a micro resistance wire mesh.

[0012] In one optional embodiment of this application, the magnetized phase transition unit includes a ferrite structure unit, a magnetite structure unit, a nickel-zinc ferrite structure unit, or a cobalt ferrite structure unit.

[0013] In one optional embodiment of this application, both the temperature-controlled phase change unit and the magnetically controlled phase change unit include any one or more combinations of square ring structure units, circular ring structure units, cross-shaped structure units, Jerusalem cross-shaped structure units, and I-shaped structure units.

[0014] In one optional embodiment of this application, the matching impedance layer is a quartz glass sheet; the heating layer is disposed in conjunction with the quartz glass sheet.

[0015] In an optional embodiment of this application, the matching impedance layer includes multiple impedance structure layers stacked sequentially; and the dielectric constant of each impedance structure layer increases progressively from the upper surface to the lower surface of the matching impedance layer; the lower surface of the matching impedance layer is the surface close to the temperature-controlled phase change resonant layer.

[0016] In one optional embodiment of this application, the impedance structure layer includes at least two structural layers selected from silicon dioxide, magnesium fluoride, aluminum oxide, polyethylene terephthalate, or cyclic olefin copolymer.

[0017] In one optional embodiment of this application, the metal reflective layer is any one of a copper layer, a silver layer, an aluminum layer, or a gold layer; and the thickness of the metal reflective layer is greater than a set skin depth threshold.

[0018] The present invention provides an electromagnetic absorber comprising a matched impedance layer, a temperature-controlled phase change resonant layer, a magnetically controlled phase change modulation layer, and a metal reflective layer stacked sequentially. The temperature-controlled phase change resonant layer includes a substrate layer and a plurality of temperature-controlled phase change units periodically arranged on the substrate layer, as well as a heating layer disposed on one side surface of the substrate layer. The heating layer is used to regulate the temperature of the temperature-controlled phase change units to change the conductivity of the temperature-controlled phase change resonant layer. The magnetically controlled phase change modulation layer includes a magnetically controlled coil and periodically arranged magnetically controlled phase change units. The magnetically controlled coil is used to apply magnetic fields of different magnitudes to the magnetically controlled phase change units to change the permeability of the magnetically controlled phase change material structure. The periodic dimensions of the arrangement of the temperature-controlled phase change units and the magnetically controlled phase change units are both between the nanometer and millimeter scales.

[0019] The electromagnetic wave absorber of this application utilizes two different phase change materials to form periodically arranged temperature-controlled phase change units and magnetically controlled phase change units. Through the coupling effect between the temperature-controlled phase change units and the magnetically controlled phase change units, electromagnetic wave absorption is achieved in a wider frequency range. Furthermore, by utilizing the adjustable conductivity and permeability of the temperature-controlled phase change units and the magnetically controlled phase change units under the control of temperature and magnetic field, the absorption frequency of the electromagnetic wave absorber can be switched and adjusted within a wider range, thereby better meeting the needs of various application scenarios. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the exploded structure of the electromagnetic absorber provided in the embodiments of this application;

[0022] Figure 2 A schematic diagram illustrating the switching function of the electromagnetic absorber between absorption and reflection provided in an embodiment of this application;

[0023] Figure 3 A schematic diagram of the coordinates of the electromagnetic wave reflection loss of the electromagnetic absorber, as measured by the vector network analyzer provided in the embodiments of this application. Detailed Implementation

[0024] The core of this invention is to provide an electromagnetic absorber that enables dynamic adjustment and switching of the electromagnetic absorption frequency within a wider range, meeting the needs of various application scenarios.

[0025] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of the electromagnetic absorber provided in an embodiment of this application.

[0027] In one specific embodiment of this application, the electromagnetic absorber may include:

[0028] The matching impedance layer 1, the temperature-controlled phase change resonant layer 3, the magnetically controlled phase change modulation layer 4, and the metal reflective layer 5 are stacked sequentially.

[0029] The temperature-controlled phase change resonant layer 3 includes a substrate layer 32 and a plurality of temperature-controlled phase change units 31 arranged periodically on the substrate layer 32, as well as a heating layer 2 disposed on one side surface of the substrate layer 32; the heating layer 2 is used to adjust the temperature of the temperature-controlled phase change units 31 so as to change the conductivity of the temperature-controlled phase change resonant layer 3.

[0030] The magnetically controlled phase change control layer 4 includes a magnetically controlled coil 42 and magnetically controlled phase change units 41 arranged in a periodic manner; the magnetically controlled coil 42 is used to apply magnetic fields of different magnitudes to the magnetically controlled phase change units 41 so as to change the magnetic permeability of the magnetically controlled phase change material structure.

[0031] The arrangement period size of the temperature-controlled phase change unit 31 and the magnetically controlled phase change unit 41 is between the nanometer and millimeter scales.

[0032] like Figure 1 As shown, in this application, a temperature-controlled phase change resonant layer 3 and a magnetically controlled phase change control layer 4 are sequentially stacked on the metal reflective layer 5. The temperature-controlled phase change resonant layer 3 has multiple temperature-controlled phase change units 31 arranged periodically on the substrate layer 32. The period size of the arrangement of each temperature-controlled phase change unit 31 is between the nanometer and millimeter scales. For example, the period size of the temperature-controlled phase change unit 31 can be 5 mm, specifically set based on the target frequency to be absorbed by the electromagnetic absorber. Based on the cooperation between each temperature-controlled phase change unit 31 and the metal reflective layer 5, a resonant structure for the target electromagnetic wave is formed, preventing the target electromagnetic wave incident on the electromagnetic absorber from being reflected. Furthermore, the dielectric loss, magnetic loss, and dielectric loss of the substrate layer 32 generated by the temperature-controlled phase change unit 41 and the magnetically controlled phase change unit 41 work together to consume and absorb the energy of the electromagnetic wave, thereby achieving the purpose of wave absorption.

[0033] Based on this, the temperature-controlled phase change unit 31 and the magnetically controlled phase change unit 41 in this application are formed of two different phase change materials. The conductivity of the temperature-controlled phase change unit 31 can change with different temperatures, while the magnetically controlled phase change unit 41 exhibits significant changes in permeability under different magnetic fields. Therefore, in practical applications, the temperature of each temperature-controlled phase change unit 31 can be controlled by the heating layer 2 to change its conductivity. At the same time, the magnetic field strength of the environment where the magnetically controlled phase change unit 41 is located can be controlled by the magnetically controlled coil 42 to change its permeability. During the absorption of incident electromagnetic waves, the electromagnetic parameter changes between the temperature-controlled phase change unit 31 and the magnetically controlled phase change unit 41 are mutually coupled and enhanced through the synergistic effect of thermal stimulation and the external magnetic field. This makes the electromagnetic absorber adjustable and improve in terms of absorption bandwidth, absorption peak shift, and absorption intensity, thereby meeting more diverse application scenarios.

[0034] In addition, Figure 1 The embodiment shown is illustrated with the temperature-controlled phase change unit 31 having a roughly columnar structure. However, in practical applications, the temperature-controlled phase change unit 31 can also be a thin-film structure unit. This application does not impose specific restrictions on this, as long as it has electrical conductivity in the process of achieving the wave absorption function.

[0035] Furthermore, the shape of each temperature-controlled phase change unit 31 in this application can be any one or more combinations of square ring structure units, circular ring structure units, cross-shaped structure units, Jerusalem cross-shaped structure units, and I-shaped structure units. For example, each temperature-controlled phase change unit 31 can be a directional ring structure unit with a period size of 5 mm. In addition, the shape and structure of each magneto-controlled phase change unit 41 can be the same as or different from that of the temperature-controlled phase change unit 31, and no specific restrictions are placed on this in this application.

[0036] Based on this, the temperature-controlled phase change unit 31 in this application may include a rare earth nickelate unit, a vanadium dioxide unit, or a modified vanadium dioxide unit; wherein, the modified vanadium dioxide unit is a vanadium dioxide unit doped with any one of tungsten, fluorine, aluminum, or titanium.

[0037] like Figure 2 As shown, the rare earth nickelate unit in this embodiment can be samarium nickelate (… Samarium nickelate units are material structures that can switch between insulating and metallic states. For conventional samarium nickelate materials, the phase transition critical temperature is approximately 130°C. Near this critical temperature, a transition between a primary metallic state and an insulating state can occur, resulting in a several-order-of-magnitude abrupt change in conductivity. In practical applications, samarium nickelate units are formed epitaxially on a substrate layer 32 using pulsed laser deposition or magnetron sputtering techniques. For example, they can be formed on a substrate (i.e., substrate layer 32) with a small in-plane lattice constant. The samarium nickelate units are deposited in a periodic arrangement. During the formation of the samarium nickelate units, the compressive strain effect is used to optimize the lattice mismatch between the samarium nickelate units and the substrate, thereby reducing and stabilizing the phase transition temperature of the samarium nickelate units at about 60°C. This can greatly reduce the difficulty of temperature control of the heating layer 2.

[0038] Based on this, the temperature of the samarium nickelate unit can be controlled within the range of 50°C to 100°C through the heating layer 2. When the temperature of the samarium nickelate unit is higher than the phase transition critical temperature, it exhibits a metallic state with high conductivity, thereby achieving the function of absorbing waves. For example, when the samarium nickelate unit is in a metallic state, the electromagnetic absorber exhibits strong absorption characteristics in the 8-12GHz X-band, with an absorption rate of over 90%. However, when the temperature of the samarium nickelate unit is lower than the phase transition critical temperature, it exhibits an insulating state with low conductivity. At this time, the samarium nickelate unit is equivalent to a "transparent" dielectric layer relative to electromagnetic waves, and therefore does not have the function of absorbing waves. In this case, the metal reflective layer 5 can reflect the incident electromagnetic waves.

[0039] Therefore, the heating layer 2 in this embodiment controls the temperature of the samarium nickelate unit similarly to a temperature control switch in an electromagnetic wave absorber. When the electromagnetic wave absorber needs to activate its absorption function, the heating layer 2 heats the samarium nickelate unit above the phase transition critical temperature. Conversely, when the electromagnetic wave absorber needs to deactivate its absorption function, the heating layer 2 regulates its temperature below the phase transition critical temperature, thus making the electromagnetic wave absorber essentially a reflective device for electromagnetic waves. Therefore, the electromagnetic wave absorber in this embodiment can not only adjust the absorption frequency based on actual needs but also control the activation and deactivation of the absorption function.

[0040] Furthermore, by precisely controlling the heating power to maintain the samarium nickelate unit in the critical region of phase transition (mixed phase state), continuous and fine adjustment of the absorption intensity and resonant frequency can be achieved, thereby realizing continuous control of the absorption frequency of the electromagnetic absorber.

[0041] Of course, the temperature-controlled phase change unit 31 in this application is not limited to samarium nickelate units. For example, the temperature-controlled phase change unit 31 can also be a vanadium dioxide unit or a modified vanadium dioxide unit. Vanadium dioxide, like other phase change materials, is capable of switching between metallic and insulating states. Its critical phase change temperature is approximately 68°C. Near this critical temperature, vanadium dioxide undergoes a first-order phase change from a low-temperature monoclinic phase (semiconductor / insulator state) to a high-temperature rutile phase (metallic state), and its conductivity can increase sharply by 4-5 orders of magnitude within an extremely narrow temperature range. Therefore, the vanadium dioxide unit can also be used to control the on / off operation of the electromagnetic wave absorber's absorption function.

[0042] Modified vanadium dioxide units are material units doped with elements such as tungsten, fluorine, aluminum, and titanium in vanadium dioxide. Compared with conventional vanadium dioxide units, the phase transition characteristics of vanadium dioxide can be changed to a certain extent by doping with modified elements. For example, the phase transition critical temperature of modified vanadium dioxide units doped with tungsten (W) can be effectively reduced from 68°C to room temperature or lower, thereby reducing the difficulty of temperature control of heating layer 2. Another example is that modified vanadium dioxide units doped with fluorine (F) can reduce the phase transition thermal hysteresis loop, making the switching behavior of the electromagnetic wave absorber sharper. It can be seen that modified vanadium dioxide units can have better environmental adaptability.

[0043] Based on this, the substrate layer 32 in the temperature-controlled phase change resonant layer 3 mainly serves to support the temperature-controlled phase change unit 31. It can be any structural layer selected from polyimide, epoxy resin, polydimethylsiloxane, polyurethane polymer, or ceramic layers. As a support for the temperature-controlled phase change unit 31, the substrate layer 32 can preferably be formed using materials with low loss and good mechanical and thermal stability, such as a single-crystal oxide substrate (e.g., ...). Functional ceramics or high-temperature resistant polymers, etc., are not subject to excessive restrictions in this application.

[0044] In addition, the temperature-controlled phase change unit 31 disposed on the substrate layer 32 may protrude from the upper surface of the substrate layer 32 (i.e., the surface near the matching impedance layer 1) or be embedded inside the substrate layer 32. This application does not specifically limit this.

[0045] Furthermore, the heating layer 2 used to control the temperature of the temperature-controlled phase change unit 31 on the substrate layer 32 can be attached to the lower surface of the substrate layer 32, or it can be located on one side of the upper surface of the substrate layer 32 and attached to the matching impedance layer 1.

[0046] In one optional embodiment of this application, the heating layer 2 may include an indium tin oxide film, a fluorine-doped tin oxide film, a silver nanowire mesh film, a graphene film, or a micro resistance wire mesh.

[0047] Taking the heating layer 2 bonded to the matching impedance layer 1 as an example, the matching impedance layer 1 can be a quartz glass sheet, thereby forming a transparent conductive heating film on the lower surface of the quartz glass sheet by magnetron sputtering. That is, it can be any one of the following films: indium tin oxide film, fluorine-doped tin oxide film, silver nanowire mesh film, and graphene film.

[0048] In addition, the heating layer 2 can also be a mesh of tiny resistance wires attached to a quartz glass plate, which heats up the temperature-controlled phase change unit 31 by passing electricity, thus achieving the same technical solution of this application.

[0049] In addition, in another optional embodiment of this application, the heating layer 2 may also include two side structures respectively disposed on the upper and lower sides of the substrate layer 32. For example, a quartz glass sheet may be disposed on the upper surface of the substrate layer 32 and a heating film may be deposited on the quartz glass sheet, while a heating coil 20 may be formed on the lower surface of the substrate layer 32. Through the combined synergistic effect of the heating film and the heating coil 20, a more uniform and rapid temperature control and adjustment of the temperature-controlled phase change unit 31 can be achieved.

[0050] Based on any of the above embodiments, the main function of the magnetically controlled phase change control layer 4 located between the temperature-controlled phase change resonant layer 3 and the metal reflective layer 5 is to generate magnetic medium loss of the incident electromagnetic wave energy, thereby achieving the purpose of absorbing electromagnetic waves.

[0051] In another optional embodiment of this application, the magnetically controlled phase transition unit 41 in the magnetically controlled phase transition control layer 4 may include a ferrite structure unit, a magnetite structure unit, a nickel-zinc ferrite structure unit, or a cobalt ferrite structure unit.

[0052] Similar to the temperature-controlled phase change unit 31 described above, the magnetically controlled phase change unit 41 in this embodiment is also a structural unit formed of a phase change material. The difference is that the magnetically controlled phase change unit 41 is a phase change material whose permeability changes with the magnetic field of its environment. This magnetically controlled phase change unit 41 can be formed from a composite material with magnetic particles or from a magnetorheological material. For example, the magnetically controlled phase change unit 41 can specifically be a ferrite structural unit, a magnetite structural unit, a nickel-zinc ferrite structural unit, a cobalt ferrite structural unit, or other magnetic alloys. In short, the goal is to ensure that the permeability or complex permittivity of the magnetically controlled phase change unit 41 changes continuously and reversibly with the magnitude or direction of the magnetic field. For example, nickel-zinc ferrite micropowder can be composited with epoxy resin, cast into a film, and then embedded into a pre-wound planar spiral copper coil. It is understood that the planar spiral coil is a heating coil 20 used to heat the temperature-controlled phase change unit 31; the heating coil 20 and the magnetically controlled phase change unit 41 are integrated in a stacked, coplanarly embedded or three-dimensionally interwoven manner, thereby improving the structural compactness of the electromagnetic absorber to a certain extent.

[0053] The magnetic control coil 42 that provides different magnetic fields for the magnetic control phase change unit 41 can be an excitation coil arranged around the outer periphery of each magnetic control phase change unit 41. That is, each magnetic control phase change unit 41 can be located inside the ring of the magnetic control coil 42 and not in direct contact with the magnetic control coil 42. In short, it is sufficient to provide a uniform magnetic field to the space where the magnetic control phase change unit 41 is located.

[0054] Furthermore, similar to the temperature-controlled phase change unit 31 described above, the magnetic phase control unit in this embodiment can be in the form of a columnar structure, and specifically can be any one or more combinations of square ring structure unit, circular ring structure unit, cross-shaped structure unit, Jerusalem cross-shaped structure unit and I-shaped structure unit; for example, each magnetic phase control unit includes a circular ring structure unit and a cross-shaped structure unit disposed within its ring.

[0055] Based on any of the above embodiments, the matching impedance layer 1 in this application is disposed on the upper surface of the temperature-controlled phase change resonant layer 3, serving as the first interface for electromagnetic wave incidence. Its core function is to achieve a smooth transition of wave impedance. This matching impedance layer 1 is formed by selecting a low-loss dielectric material (such as silicon dioxide, magnesium fluoride, or a specific polymer) with a specific dielectric constant and thickness. This minimizes Fresnel reflection of electromagnetic waves at the air-material interface, forcing most of the incident electromagnetic wave energy to enter the absorbing material, creating prerequisites for subsequent loss and absorption. To achieve a wider bandwidth absorption effect, the matching impedance layer 1 can also be designed as a multi-layered gradient impedance structure, thereby simulating an ideal impedance gradient channel.

[0056] In an optional embodiment of this application, the matching impedance layer 1 may include multiple layers of impedance structures stacked sequentially; and the dielectric constant of each impedance structure layer increases progressively from the upper surface to the lower surface of the matching impedance layer 1; the lower surface of the matching impedance layer 1 is the surface close to the temperature-controlled phase-change resonant layer 3. To achieve wider bandwidth matching, the matching impedance layer 1 may adopt a multilayer dielectric stacked structure, with the dielectric constant of each impedance structure layer set in a progressively increasing manner; the thickness of each impedance structure layer may be the same, for example, approximately equal to 1 / 4 wavelength of the target frequency or increasing progressively, which is equivalent to forming a continuous impedance structure, significantly widening the matching bandwidth.

[0057] Each impedance structure layer may include at least two of the following: a silicon dioxide layer, a magnesium fluoride layer, an aluminum oxide layer, a polyethylene terephthalate layer, or a cyclic olefin copolymer layer; as long as the final impedance structure layer can satisfy the requirement of a progressively increasing dielectric constant.

[0058] Based on the above discussion, the metal reflective layer 5 in the electromagnetic absorber can be any one of a copper layer, a silver layer, an aluminum layer, or a gold layer; and the thickness of the metal reflective layer 5 is greater than a set skin depth threshold, which is the skin depth of the electromagnetic wave in the metal reflective layer 5.

[0059] The metal reflective layer 5, located at the bottom of the structure, acts as an ideal electromagnetic "barrier," reflecting almost all the residual electromagnetic wave energy that has penetrated the temperature-controlled phase-change resonant layer 3 and the magnetically controlled phase-change modulation layer 4 but was not completely absorbed. This causes the energy to undergo another loss process, thus forming a highly efficient wave-absorbing structure that greatly improves the absorption efficiency of a single incident energy. Furthermore, when the temperature-controlled phase-change unit 31 is in an insulating state, it can also act as an electromagnetic wave reflective layer to strongly reflect electromagnetic waves.

[0060] In summary, the electromagnetic wave absorber of this application utilizes two different phase change materials to form periodically arranged temperature-controlled phase change units and magnetically controlled phase change units. Through the coupling effect between the temperature-controlled and magnetically controlled phase change units, electromagnetic wave absorption over a wider frequency range is achieved. Furthermore, by utilizing the adjustable conductivity and magnetic flux density of the temperature-controlled and magnetically controlled phase change units under temperature and magnetic field control, the absorption frequency of the electromagnetic wave absorber can be switched and adjusted over a wider range, thereby better meeting the needs of various application scenarios.

[0061] In one optional embodiment of this application, the electromagnetic absorber comprises, from top to bottom:

[0062] Matching impedance layer 1, which uses a 1.5 mm quartz glass sheet as a substrate, and on the upper surface of the substrate, a multilayer impedance structure layer with progressively increasing dielectric constant is stacked from top to bottom.

[0063] A 100 nm thick indium tin oxide film is deposited on the lower surface of a quartz glass plate as a heating electrode;

[0064] The upper surface is integrated with The resonant unit of the square ring array has a polyimide (PI) matrix with a thickness of 2.0 mm;

[0065] A magnetically controlled phase change control layer 4 is formed of a ferrite-polymer composite material to form a magnetically controlled phase change unit 41, wherein a heating coil 20 is embedded in the magnetically controlled phase change control layer 4.

[0066] And copper foil as a total reflection backplate.

[0067] like Figure 2 and Figure 3 As shown, Figure 3A schematic diagram of the coordinates of the electromagnetic wave reflection loss of the electromagnetic absorber, as measured by the vector network analyzer provided in the embodiments of this application.

[0068] In this embodiment, the electromagnetic absorber operates without any thermal excitation. The square ring array is at room temperature. The square ring is in an insulating state; tests using a vector network analyzer show that, within the 8-18 GHz range, it behaves as a broadband strong reflector of electromagnetic waves, i.e., in an "off" state.

[0069] When a direct current is applied to the heating electrode and the heating coil 20, the temperature of the SmNiO3 square ring array can be raised to above 70°C, causing the SmNiO3 square ring array to transform into a metallic state. Without the application of an external magnetic field, the electromagnetic absorber exhibits excellent broadband absorption performance in the X-band, with an effective absorption frequency band (reflection loss ≤ -10 dB) covering 7.2 GHz to 12.72 GHz, and an absorption peak is observed at 9.04 GHz, with a peak value of -28.49 dB.

[0070] When in When the square ring array processes the metallic state and has a microwave absorption function, when a constant magnetic field of 0.1 T is applied to the magnetic phase change unit 41 through the magnetic control coil 42, the absorption characteristics of the electromagnetic absorber undergo an overall frequency shift, and the effective absorption frequency band shifts to 12.28 GHz to 18 GHz, covering the main range of the Ku band. At the same time, a new absorption peak appears at 15.28 GHz, and its reflection loss is further reduced to -38.83 dB, showing a stronger electromagnetic loss capability.

[0071] Thus, it can be seen that the electromagnetic absorber in this embodiment realizes the "on" and "off" of the macroscopic absorption function; at the same time, the magnetic field control realizes the continuous and reversible shift of the absorption frequency band from the X band to the Ku band, and the absorption performance is maintained or even enhanced during the tuning process, which verifies the effectiveness and practicality of the thermo-magnetic dual-field synergistic control mechanism.

[0072] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0073] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. An electromagnetic absorber, characterized in that, It includes a matching impedance layer, a temperature-controlled phase change resonant layer, a magnetically controlled phase change modulation layer, and a metal reflective layer stacked sequentially. The temperature-controlled phase change resonant layer includes a substrate layer and a plurality of temperature-controlled phase change units arranged periodically on the substrate layer, as well as a heating layer disposed on one side surface of the substrate layer; the heating layer is used to adjust the temperature of the temperature-controlled phase change units so as to change the conductivity of the temperature-controlled phase change resonant layer. The magnetically controlled phase change control layer includes a magnetically controlled coil and magnetically controlled phase change units arranged in a periodic manner; the magnetically controlled coil is used to apply magnetic fields of different magnitudes to the magnetically controlled phase change units to cause the magnetic permeability of the magnetically controlled phase change material structure to change. The arrangement period of both the temperature-controlled phase change unit and the magneto-controlled phase change unit is between the nanometer and millimeter scales.

2. The electromagnetic absorber as described in claim 1, characterized in that, The temperature-controlled phase change unit includes a rare earth nickelate unit, a vanadium dioxide unit, or a modified vanadium dioxide unit; wherein the modified vanadium dioxide unit is a vanadium dioxide unit doped with any one of tungsten, fluorine, aluminum, or titanium.

3. The electromagnetic absorber as described in claim 1, characterized in that, The substrate layer includes a polyimide layer, an epoxy resin layer, a polydimethylsiloxane layer, a polyurethane polymer layer, or a ceramic layer.

4. The electromagnetic absorber as described in claim 1, characterized in that, The heating layer includes an indium tin oxide thin film, a fluorine-doped tin oxide thin film, a silver nanowire mesh thin film, a graphene thin film, or a micro resistance wire mesh.

5. The electromagnetic absorber as described in claim 1, characterized in that, The magneto-controlled phase transition unit includes a ferrite structure unit, a magnetite structure unit, a nickel-zinc ferrite structure unit, or a cobalt ferrite structure unit.

6. The electromagnetic absorber as described in claim 1, characterized in that, Both the temperature-controlled phase change unit and the magnetically controlled phase change unit include any one or more combinations of square ring structure units, circular ring structure units, cross-shaped structure units, Jerusalem cross-shaped structure units, and I-shaped structure units.

7. The electromagnetic absorber as described in claim 1, characterized in that, The matching impedance layer is a quartz glass sheet; the heating layer is attached to the quartz glass sheet.

8. The electromagnetic absorber as described in claim 1, characterized in that, The matching impedance layer includes multiple impedance structure layers stacked sequentially; and the dielectric constant of each impedance structure layer increases progressively from the upper surface to the lower surface of the matching impedance layer; the lower surface of the matching impedance layer is the surface close to the temperature-controlled phase change resonant layer.

9. The electromagnetic absorber as described in claim 8, characterized in that, The impedance structure layer includes at least two of the following structural layers: a silicon dioxide layer, a magnesium fluoride layer, an aluminum oxide layer, a polyethylene terephthalate layer, or a cyclic olefin copolymer layer.

10. The electromagnetic absorber as described in claim 1, characterized in that, The metal reflective layer is any one of a copper layer, a silver layer, an aluminum layer, or a gold layer; and the thickness of the metal reflective layer is greater than a set skin depth threshold.

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