A microwave broadband absorber integrating SSPP structure and magnetic film

Abstract

The present invention provides a microwave broadband absorber integrating SSPP structure and magnetic film, including an absorbing structure and a metal bottom plate; the SSPP structure utilizes the dispersion effect to realize slow wave transmission in a frequency band, and then realizes the absorption of electromagnetic waves through the ohmic loss of silver paste; the magnetic film utilizes the localization and slow wave characteristics of the SSPP structure to realize the loss absorption of low-frequency electromagnetic waves; the metal bottom plate provides a reflection surface to make the transmission zero; the SSPP structure includes a plurality of first absorbers and second absorbers with the same structure; the first absorber and the second absorber both include a dielectric plate and a plurality of pairs of mutually perpendicular silver paste strips laid on the dielectric plate. Two different types of absorbing mechanisms are introduced. Through the design of the two structures, the two absorbing mechanisms can be well combined to realize broadband absorption, and the disadvantage of heavy magnetic materials is overcome. The microwave broadband absorber has the characteristics of thin thickness, light weight and wide absorption frequency band.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic wave absorption, and in particular relates to a microwave broadband absorber integrating an SSPP structure and a magnetic film. Background Art

[0002] In the field of national defense and military, absorbing materials can avoid tracking and detection by enemy radars, making weapons and equipment disappear from the field of view of enemy radar detectors, thereby improving the battlefield survivability of weapons and equipment; in daily life, absorbing materials can be used to reduce electromagnetic leakage of various electronic devices and reduce the negative impact of electromagnetic waves on the human body and the environment. Therefore, absorbing materials are widely used in both military and civilian fields.

[0003] The artificial surface plasmon (SSPP) structure has a dispersion curve similar to that of surface plasmons, and can excite a surface wave on the surface of the metal structure. The surface wave is localized at the interface of the medium / metal / air, and its group velocity is less than the speed of light in a vacuum. People can adjust the dispersion characteristics of the SSPP by adjusting the parameters of the artificial structure, thereby exciting slow waves in a specified frequency band, and then absorb electromagnetic waves by introducing lossy materials. This is the first absorption mechanism.

[0004] Magnetic absorbers filled with magnetic absorbents have the advantages of simple process and easy use. They are relatively mature in technology and widely used in engineering. This is the second absorption mechanism. However, since magnetic materials have no structural strength and need to be coated on the surface of objects, their typical weight per square meter is generally between 1.5 and 4 kg, and their thickness is between 0.5 and 1 mm, so the use of magnetic materials will greatly increase the weight.

[0005] At present, there have been studies on electromagnetic wave absorption based on SSPP. For example, the literature (Merging absorption bands of plasmonic structures via dispersion engineering) proposed a broadband electromagnetic wave absorber with customizable absorption, but the thickness of the absorber is 10 mm.

[0006] There are also studies on combining SSPP absorbers with magnetic materials. For example, the paper (Integrating absorber with non-planar plasmonic structure for k-vector matching absorption enhancement) proposes a broadband absorber that integrates magnetic materials and SSPP. However, this solution is just a simple combination of planar magnetic materials and three-dimensional SSPP. The magnetic material greatly increases the mass of the structure. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a microwave broadband absorber integrating an SSPP structure and a magnetic film.

[0008] The present invention provides a microwave broadband absorber integrating an SSPP structure and a magnetic film, comprising an absorbing structure and a metal bottom plate arranged in sequence from top to bottom;

[0009] The wave absorbing structure includes an SSPP structure and a magnetic film; the SSPP structure uses the dispersion effect to achieve slow wave transmission in a frequency band, and then absorbs electromagnetic waves through the ohmic loss of the silver paste; the magnetic film uses the localization and slow wave characteristics of the SSPP structure to achieve loss absorption of low-frequency electromagnetic waves; the metal bottom plate provides a reflection surface to make the transmission zero;

[0010] The SSPP structure includes a plurality of first absorbers and second absorbers with the same structure; the first absorbers and the second absorbers both include a dielectric plate and a plurality of pairs of mutually perpendicular silver paste strips laid on the dielectric plate; a pair of the silver paste strips are respectively parallel to the metal base plate and perpendicular to the metal base plate; the lengths of the plurality of pairs of mutually perpendicular silver paste strips increase from top to bottom; the two ends of each of the first absorbers are respectively perpendicularly connected to a second absorber; two of the first absorbers and two of the second absorbers constitute an absorbing unit of the SSPP; and the central axis of the absorbing unit is perpendicular to the metal base plate.

[0011] Furthermore, the magnetic film is located on a side of the dielectric plate away from the silver paste strip.

[0012] Furthermore, the thickness of the magnetic film does not exceed 0.2 mm.

[0013] Furthermore, the metal base plate is a conductive material capable of totally reflecting electromagnetic waves.

[0014] Furthermore, the dielectric board is a FR-4 substrate.

[0015] Furthermore, the dispersion curve and wave absorption performance of the structure can be changed by adjusting the logarithm and length of the mutually perpendicular silver paste strips.

[0016] The invention provides a microwave broadband absorber integrating an SSPP structure and a magnetic film, comprising an absorber structure and a metal bottom plate arranged in sequence from top to bottom; the absorber structure comprises an SSPP structure and a magnetic film; the SSPP structure utilizes a dispersion effect to realize slow-wave transmission of a frequency band, and then realizes the absorption of electromagnetic waves through the ohmic loss of silver paste; the magnetic film utilizes the localization and slow-wave characteristics of the SSPP structure to realize the loss absorption of low-frequency electromagnetic waves; the metal bottom plate provides a reflection surface to make the transmission zero; the SSPP structure comprises a plurality of first absorbers and second absorbers with the same structure; the first absorber and the second absorber both comprise a dielectric plate and a plurality of pairs of mutually perpendicular silver paste strips laid on the dielectric plate; a pair of the silver paste strips are respectively parallel to the metal bottom plate and perpendicular to the metal bottom plate; the lengths of the plurality of pairs of mutually perpendicular silver paste strips increase in sequence from top to bottom; the two ends of each of the first absorbers are respectively perpendicularly connected to a second absorber; two of the first absorbers and two of the second absorbers constitute an absorbing unit of the SSPP; the central axis of the absorbing unit is perpendicular to the metal bottom plate.

[0017] The SSPP structure and magnetic film introduce two different types of wave absorption mechanisms respectively. Through the design of the two structures, these two wave absorption mechanisms can be well combined to achieve broadband wave absorption and overcome the disadvantage of heavy magnetic materials. The microwave broadband absorber has the characteristics of thin thickness, light weight and wide absorption frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic structural diagram of a microwave broadband absorber integrating an SSPP structure and a magnetic film provided in an embodiment of the present invention;

[0020] Figure 2 The dispersion diagram and wave velocity diagram of the SSPP provided by the embodiment of the present invention, wherein (a) is the dispersion curve and (b) is the wave velocity;

[0021] Figure 3 Energy distribution diagram of a microwave broadband absorber integrating an SSPP structure and a magnetic film provided in an embodiment of the present invention;

[0022] Figure 4Electromagnetic parameter diagram of a magnetic film provided by an embodiment of the present invention;

[0023] Figure 5 A reflection coefficient curve diagram of a simulated microwave broadband absorber integrating an SSPP structure and a magnetic film provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, the embodiment of the present invention partially provides a microwave broadband absorber integrating SSPP structure and magnetic film, comprising an absorbing structure 1 and a metal bottom plate 2 arranged in sequence from top to bottom, wherein the height of the absorbing structure 1 is h.

[0026] The wave-absorbing structure 1 includes a SSPP structure 11 and a magnetic film 12; the SSPP structure 11 uses the dispersion effect to achieve slow-wave transmission in a frequency band, and then absorbs electromagnetic waves through the ohmic loss of the silver paste; the magnetic film 12 uses the locality and slow-wave characteristics of the SSPP structure 11 to achieve loss absorption of low-frequency electromagnetic waves; the metal base plate 2 provides a reflection surface to make the transmission zero. The silver paste material used in the SSPP structure 11 has a certain ohmic loss itself and can absorb high-frequency electromagnetic waves. At low frequencies, the SSPP structure 11 also has a certain local effect on electromagnetic waves, which enhances the effect of electromagnetic waves and magnetic materials, so that the very thin magnetic film 12 also has a good wave-absorbing effect. In addition, the slow-wave characteristics of the SSPP structure 11 are also reflected at low frequencies. According to the following formula, under slow waves, slower wave speeds are also conducive to the absorption of magnetic materials at low frequencies:

[0027] ;

[0028] in, and are the magnetic permeability and dielectric constant of the absorbing material respectively; f is the frequency; h is the material thickness; is the wave speed; The wave impedance in vacuum is 377Ω, is the input impedance of the absorbing material, is the reflection coefficient, and Absorption is the absorption rate.

[0029] The SSPP structure 11 includes a plurality of first absorbers 111 and second absorbers 112 of the same structure; the first absorbers 111 and the second absorbers 112 both include a dielectric plate 113 and a plurality of pairs of mutually perpendicular silver paste strips 114 laid on the dielectric plate 113; the dielectric plate 113 only plays a supporting role, while the plurality of pairs of mutually perpendicular silver paste strips 114 can excite SSPP; a pair of silver paste strips 114 are respectively parallel to the metal base plate 2 and perpendicular to the metal base plate 2; the lengths of the plurality of pairs of mutually perpendicular silver paste strips 114 increase from top to bottom; the two ends of each first absorber 111 are respectively vertically connected to a second absorber 112; the two first absorbers 111 and the two second absorbers 112 constitute an absorbing unit of SSPP; the central axis of the absorbing unit is perpendicular to the metal base plate 2. In the embodiment of the present invention, the logarithm of the mutually perpendicular silver paste strips 114 of an absorber is 12, and the width of the silver paste strips 114 is 0.2 mm; the parameters of the microwave broadband absorber are as follows: the length of the metal base plate p=10 mm, the height of the absorbing structure is h=5 mm, the longest length of the silver paste strip parallel to the metal base plate a=9.1 mm, the length of the silver paste strip perpendicular to the metal base plate b=4.6 mm, the shortest length of the silver paste strip parallel to the metal base plate d=4.7 mm, the thickness of the dielectric plate t=0.75 mm, and the thickness of the magnetic film u=0.15 mm.

[0030] Optionally, the magnetic film 12 is located on a side of the dielectric plate 113 away from the silver paste strip 114 .

[0031] Optionally, the thickness of the magnetic film 12 does not exceed 0.2 mm.

[0032] Optionally, the metal base plate 2 is a conductive material capable of totally reflecting electromagnetic waves.

[0033] Optionally, the dispersion curve and wave absorption performance of the control structure can be changed by adjusting the logarithm and length of the mutually perpendicular silver paste strips 114 .

[0034] The CST STUDIO SUITE software was used to perform theoretical calculations on the model. The mutually perpendicular silver paste strips 114 of different lengths have the following characteristics: Figure 2In the dispersion curve shown in , the shortest length of the silver paste strips 114 parallel to the metal base plate 2 is denoted as line Ⅰ, and the longest length of the silver paste strips 114 parallel to the metal base plate 2 is denoted as line Ⅱ. Among them, the silver paste strips 114 parallel to the metal base plate 2 have a lower cutoff frequency, and the silver paste strips 114 perpendicular to the metal base plate 2 have a longer cutoff frequency. Each pair of mutually perpendicular silver paste strips 114 will absorb electromagnetic waves near the cutoff frequency. A structure composed of multiple mutually perpendicular silver paste strips 114 of different lengths can achieve broadband absorption. Furthermore, the group velocity of mutually perpendicular silver paste strips 114 of different lengths was calculated, proving that the group velocity of the SSPP structure 11 near the cutoff frequency is close to 0, and the wave velocity can be effectively reduced below the cutoff frequency.

[0035] like Figure 3 As shown in the figure, SSPP can localize electromagnetic waves near the silver paste strip 114 on one side of the dielectric plate 113. When the horizontal axis in the figure is at 7 GHz, SSPP strengthens the coupling between the electromagnetic waves and the magnetic film, so that the energy at the magnetic film is significantly enhanced, and the low-frequency absorption performance of the magnetic material is improved; at 12 GHz, the magnetic material has almost no effect on the local characteristics of SSPP, and does not destroy the high-frequency absorption performance of SSPP.

[0036] like Figure 4 As shown, the magnetic film 12 has large electric loss and magnetic loss. Under the effect of the localization and slow wave characteristics of SSPP, low-frequency absorption can be achieved with only a very thin magnetic film 12, overcoming the disadvantage of traditional magnetic materials that increase weight.

[0037] like Figure 5 As shown, the microwave broadband absorber can achieve an absorption rate greater than 90% in the 5.2-18 GHz band.

[0038] The FR-4 substrate with a relative dielectric constant of 4.3 and a loss tangent of 0.025 is used as the dielectric plate 113, and the silver paste strip 114 with a square resistance of 1.5 Ohm / sq is used as the structure for exciting SSPP. The 0.15 mm thick magnetic film 12 is used, and other thin film materials with high wave absorption can also be used. The metal base plate 2 can be made of copper, iron, aluminum and other metals as a reflective surface.

[0039] The performance of the present invention is better than the SSPP absorber recorded in the literature mentioned in the background technology; compared with the absorber based on magnetic materials, the microwave broadband absorber of the present invention has the advantage of significant weight reduction.

[0040] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A microwave broadband absorber integrating SSPP structure and magnetic film, characterized in that: It includes a wave absorbing structure and a metal bottom plate arranged in sequence from top to bottom; The wave absorbing structure includes an SSPP structure and a magnetic film; the SSPP structure uses the dispersion effect to achieve slow wave transmission in a frequency band, and then absorbs electromagnetic waves through the ohmic loss of the silver paste; the magnetic film uses the localization and slow wave characteristics of the SSPP structure to achieve loss absorption of low-frequency electromagnetic waves; the metal bottom plate provides a reflection surface to make the transmission zero; The SSPP structure comprises a plurality of first absorbers and second absorbers of the same structure; the first absorbers and the second absorbers each comprise a dielectric plate and a plurality of pairs of mutually perpendicular silver paste strips laid on the dielectric plate; a pair of the silver paste strips are respectively parallel to the metal bottom plate and perpendicular to the metal bottom plate; the lengths of the plurality of pairs of mutually perpendicular silver paste strips increase from top to bottom; the two ends of each of the first absorbers are respectively perpendicularly connected to a second absorber; two of the first absorbers and two of the second absorbers constitute an absorber unit of the SSPP; the central axis of the absorber unit is perpendicular to the metal bottom plate; The magnetic film is located at a side of the dielectric plate away from the silver paste strip.

2. The microwave broadband absorber according to claim 1, characterized in that: The thickness of the magnetic film does not exceed 0.2 mm.

3. The microwave broadband absorber according to claim 1, characterized in that: The metal bottom plate is a conductive material capable of totally reflecting electromagnetic waves.

4. The microwave broadband absorber according to claim 1, characterized in that: The dielectric plate is a FR-4 substrate.

5. The microwave broadband absorber according to claim 1, characterized in that: The dispersion curve and wave absorption performance of the structure can be changed by adjusting the logarithm and length of the mutually perpendicular silver paste strips.

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