A low-pass, high-absorption energy selective surface based on magnetic materials

Abstract

This invention discloses a low-pass, high-absorption energy selective surface based on magnetic materials, comprising multiple periodically distributed units. Each unit includes, from top to bottom, a magnetic material layer and an energy selective layer. The energy selective layer includes a dielectric substrate, and first to seventh metal structures and first to eighth diodes disposed on the dielectric substrate. This invention achieves a low-intervention, low-frequency passband with low insertion loss and an ultra-wide absorption band at high frequencies by forming a complete circuit through multiple diodes and impedance matching between the magnetic material and the energy selective layer. When low-power electromagnetic waves are incident, it achieves high shielding effectiveness within the operating frequency band and an ultra-wide absorption band outside the band. The overall design of this invention is simple, the principle is clear, it is easy to manufacture, and it is inexpensive, with broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic protection and stealth technology, and relates to a low-pass, high-absorption energy selective surface based on magnetic materials, which can be applied to electromagnetic compatibility and protection fields such as stealth technology and protection technology. Background Technology

[0002] An Energy Selective Surface (ESS) consists of a frequency selective surface and diodes, and is often used as a novel electromagnetic shielding technology. In an electromagnetic environment, if low-power electromagnetic waves are incident on a periodically structured electromagnetic surface, they will selectively pass through the desired electromagnetic band. In an environment subjected to high-power electromagnetic waves, the diodes on the electromagnetic surface will be activated and conduct, forming a protective shield. This reduces the interference and damage of electromagnetic pulses to electronic equipment, thus achieving the effect of electromagnetic protection.

[0003] Frequency selective surfaces, which transmit electromagnetic waves within their operating frequency band and absorb electromagnetic waves outside their operating frequency band, have important applications in electromagnetic protection and electromagnetic stealth. Currently, the main method for out-of-band absorption is using absorbing materials, whose structures are mostly designed based on metal backplates to achieve their absorption characteristics. Compared to absorbing waves using structures and resistors, absorbing materials are easier to design and manufacture, and can achieve better absorption effects.

[0004] Currently, most common energy selective surfaces adopt a bandpass structure design, while band-absorbing surfaces are usually only found in frequency selective surfaces, and there are no reports on band-absorbing energy selective surfaces. Bandpass energy selective surfaces can obtain a passband under low-power electromagnetic wave incident conditions, and the out-of-band is a reflection band. Under high-power electromagnetic wave incident conditions, it is a reflection band. These bandpass energy selective surfaces lack research on stealth protection characteristics outside the operating frequency band. Furthermore, the design of the operating frequency band mostly focuses on the mid-to-high frequency range, neglecting the importance of the low-frequency passband (VHF), which cannot meet the needs of low-frequency transmission and high-frequency absorption in practical applications. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a low-pass, high-absorption energy selective surface based on magnetic materials. This structure achieves a low-insertion-loss low-frequency passband and an ultra-wide absorption band at high frequencies by cascading a layer of magnetic material with an energy selective surface and performing impedance matching. When low-power electromagnetic waves are incident, it achieves high shielding effectiveness within the operating frequency band and an ultra-wide absorption band outside the band. This invention has a simple overall design, a clear principle, is easy to manufacture, has low cost, and has broad application prospects.

[0006] The present invention provides a low-pass, high-absorption energy selective surface based on magnetic materials with a vertically arranged structure. The structure consists of periodically distributed units (seamlessly arranged in the x and y periodic directions). Each unit has two layers from top to bottom: a magnetic material layer and an energy selective layer.

[0007] The magnetic material layer includes a piece of magnetic material with the same size as the unit cell. This magnetic material layer is located above the selectable layer, and the two layers are seamlessly bonded together with a thickness of t. m Satisfies 0.03λ a ~ 0.05λ a , λ a The wavelength corresponding to the absorption initiation frequency of the low-pass, high-absorption energy selective surface structure based on magnetic materials in this invention is shown.

[0008] The selectable layer includes a dielectric substrate and a first metal structure, a second metal structure, a third metal structure, a fourth metal structure, a fifth metal structure, a sixth metal structure, a seventh metal structure, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, and an eighth diode located on the upper surface of the dielectric substrate. Specifically: one end of the first metal structure is connected to one end of the first diode and one end of the second diode; the other end of the first diode is connected to one end of the second metal structure; the other end of the second diode is connected to one end of the third metal structure; the other end of the second metal structure is connected to one end of the third diode; the other end of the third metal structure is connected to one end of the fourth diode; and the other ends of the third diode and the fourth diode are respectively connected to one end of the seventh metal structure.

[0009] One end of the fourth metal structure is connected to one end of the fifth diode and one end of the sixth diode, respectively. The other end of the fifth diode is connected to one end of the fifth metal structure. The other end of the sixth diode is connected to one end of the sixth metal structure. The other end of the fifth metal structure is connected to one end of the seventh diode. The other end of the sixth metal structure is connected to one end of the eighth diode. The other ends of the seventh diode and the eighth diode are respectively connected to the other end of the seventh metal structure. A rectangular notch is provided in the upper left corner of the seventh metal structure to increase the inductance. The dielectric substrate is the same size as the unit size and has a thickness of t. d Satisfies 0.003λ a ~0.009λ a , λ a This refers to the wavelength corresponding to the absorption initiation frequency of the low-pass, high-absorption energy selective surface structure based on magnetic materials in this invention.

[0010] Preferably, the magnetic material layer has a square structure, with the energy selective layer seamlessly attached underneath.

[0011] Preferably, the first diode and the fifth diode are arranged symmetrically about the diagonal of the selectable layer, the second diode and the sixth diode are arranged symmetrically about the diagonal of the selectable layer, the third diode and the seventh diode are arranged symmetrically about the diagonal of the selectable layer, and the fourth diode and the eighth diode are arranged symmetrically about the diagonal of the selectable layer.

[0012] Preferably, the first metal structure and the fourth metal structure are symmetrically arranged about the diagonal of the selectable layer, the second metal structure and the fifth metal structure are symmetrically arranged about the diagonal of the selectable layer, the third metal structure and the sixth metal structure are symmetrically arranged about the diagonal of the selectable layer, and the seventh metal structure is symmetrical about the diagonal of the selectable layer.

[0013] Preferably, the dielectric substrate uses Rogers RT5008 with a dielectric constant of 2.2.

[0014] Preferably, the first diode, second diode, third diode, fourth diode, fifth diode, sixth diode, seventh diode, and eighth diode are all SKYWORKS SMP1330.

[0015] Preferably, the thickness ratio of the magnetic material layer to the energy-selective layer is 32:5.

[0016] Preferably, the magnetic material layer is impedance matched with the energy selector layer, achieving a low passband with low insertion loss and a wide high-frequency absorption band at low power, and high shielding effectiveness and a wide high-frequency absorption band at high power.

[0017] Specific working principle:

[0018] When low-power electromagnetic waves are incident, the eight diodes in the selectable layer are turned off, and the diodes can be considered equivalent to a cutoff capacitor. The selectable layer can then be considered equivalent to an LC series structure, exhibiting filtering characteristics of low-frequency transmission and high-frequency reflection. Then, through impedance matching of the magnetic material layer, a low-frequency transmission band can still be obtained at low frequencies, while at high frequencies it acts as an absorber, enabling broadband absorption.

[0019] When high-power electromagnetic waves are incident, the eight diodes in the selectable layer become conductive, and these diodes can be considered equivalent to a conducting resistor. The selectable layer then functions as an inductive structure (with negligible on-resistance), exhibiting full-band reflection filtering characteristics. Through impedance matching with the magnetic material layer, a high-efficiency shielding reflection band is achieved at low frequencies, while at high frequencies it functions as an absorber, similar to its low-power counterpart, providing broadband absorption. The use of eight diodes in the selectable layer avoids the inability to complete the circuit due to the absorption structure, ensuring a satisfactory electromagnetic response.

[0020] Compared with the prior art, the low-pass, high-absorption energy selective surface based on magnetic materials of the present invention has the following advantages:

[0021] (1) The present invention is based on a two-layer structure design that has a low-frequency transmission band and a high-frequency absorption band in the low-power case, and a low-frequency reflection shielding band and a high-frequency absorption band in the high-power case. By impedance matching between the energy selector layer and the magnetic material layer, the stealth and protection performance of the operation is improved.

[0022] (2) The low-pass, high-absorption energy selective surface provided by the present invention adopts a simple unit structure, which makes efficient use of the state of electromagnetic waves of the diode under different power, and achieves a good impedance matching effect. The design principle is very clear, which has good guiding significance for this type of work, fills the gap in energy selective surfaces in this type of work, and the design structure is very simple and low cost. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a three-dimensional structural unit of a low-pass, high-absorption energy selective surface based on magnetic materials according to the present invention.

[0024] Figure 2 This is a top view of an energy selectivity layer of a low-pass, high-absorption energy selectivity surface based on magnetic materials according to the present invention.

[0025] Figure 3 This is a front view of a low-pass, high-absorption energy selective surface based on magnetic materials according to the present invention.

[0026] Figure 4 This is an equivalent circuit diagram of a low-pass, high-absorption energy selective surface based on magnetic materials according to the present invention.

[0027] Figure 5 This is a scattering characteristic curve of a low-pass, high-absorption energy selective surface based on magnetic materials under low-power incident electromagnetic wave irradiation, according to the present invention.

[0028] Figure 6This is a scattering characteristic curve of a low-pass, high-absorption energy selective surface based on magnetic materials under high-power incident electromagnetic wave irradiation, according to the present invention.

[0029] Figure 7 This is a comparison diagram of the scattering rate of a low-pass, high-absorption energy selective surface based on magnetic materials under low-power incident electromagnetic wave irradiation, according to the present invention.

[0030] Figure 8 This is a comparison diagram of the scattering rate of a low-pass, high-absorption energy selective surface based on magnetic materials under high-power incident electromagnetic wave irradiation, according to the present invention.

[0031] The diagram is labeled as follows: Magnetic material layer 1, Selective layer 2, First metal structure 1a, First diode 1b, Second diode 1c, Second metal structure 1d, Third metal structure 1e, Third diode 1f, Fourth diode 1g, Fourth metal structure 2a, Fifth diode 2b, Sixth diode 2c, Fifth metal structure 2d, Sixth metal structure 2e, Seventh diode 2f, Eighth diode 2g, Seventh metal structure 3a, Dielectric substrate 3b. Detailed Implementation

[0032] The present invention will be further analyzed below with reference to specific embodiments.

[0033] like Figure 1 As shown, a low-pass, high-absorption energy selective surface based on magnetic materials has a vertically arranged structure, including periodically distributed and seamlessly covered units. Each unit includes a magnetic material layer 1 and an energy selective layer 2 from top to bottom.

[0034] like Figure 2As shown, the selectable layer 2 includes a dielectric substrate 3b and a first metal structure 1a, a second metal structure 1d, a third metal structure 1e, a fourth metal structure 2a, a fifth metal structure 2d, a sixth metal structure 2e, a seventh metal structure 3a, a first diode 1b, a second diode 1c, a third diode 1f, a fourth diode 1g, a fifth diode 2b, a sixth diode 2c, a seventh diode 2f, and an eighth diode 2g located on its upper surface. The lower side of the first metal structure 1a is connected to the second metal structure 1d and the third metal structure 1e via the first diode 1b and the second diode 1c, respectively. The second metal structure 1d and the third metal structure 1e are connected to the seventh metal structure 3a via the third diode 1f and the fourth diode 1g, respectively. The right side of the fourth metal structure 2a is connected to the fifth metal structure 2d and the sixth metal structure 2e via the fifth diode 2b and the sixth diode 2c, respectively. The fifth metal structure 2d and the sixth metal structure 2e are connected to the seventh metal structure 3a via the seventh diode 2f and the eighth diode 2g, respectively. A rectangular notch is provided in the upper left corner of the seventh metal structure 3a. The dielectric substrate 3b is the same size as the unit size and is a Rogers RT5008 with a dielectric constant of 2.2. The first diode 1b, the second diode 1c, the third diode 1f, the fourth diode 1g, the fifth diode 2b, the sixth diode 2c, the seventh diode 2f, and the eighth diode 2g are all SKYWORKS SMP1330.

[0035] like Figure 3 As shown, the magnetic material layer 1 includes a magnetic material, specifically LCXBXJ-12; its size is the same as the unit size, and the magnetic material layer 1 is located above the selectable layer 2, with the two layers seamlessly bonded together.

[0036] like Figure 4 As shown, the low-pass, high-absorption energy selective surface based on magnetic materials of the present invention can be equivalent to a specific circuit model. Magnetic material layer 1 can be equivalent to a surface with a characteristic impedance of Z. m Lossy transmission lines, where β m and t mLet L be the propagation constant and thickness of magnetic material layer 1; the first metal structure 1a, second metal structure 1d, third metal structure 1e, fourth metal structure 2a, fifth metal structure 2d, sixth metal structure 2e, and seventh metal structure 3a in selectable layer 2 can be collectively equivalent to an inductor L1; the first diode 1b and the fifth diode 2b can be equivalent to diode D3; the second diode 1c and the sixth diode 2c can be equivalent to diode D1; the third diode 1f and the seventh diode 2f can be equivalent to diode D4; and the fourth diode 1g and the eighth diode 2g can be equivalent to diode D2; the dielectric substrate 3b can be equivalent to a substrate with a characteristic impedance of Z. d Lossy transmission lines, where β d and t d Let be the propagation constant and thickness of the dielectric substrate 3b;

[0037] Based on the equivalent circuit model, the ABCD transfer matrices for magnetic material layer 1, energy selector layer 2, and dielectric substrate 3b can be obtained respectively:

[0038]

[0039] The A1B1C1D1 transfer matrix describes magnetic material layer 1, where Z m β is the characteristic impedance of the magnetic material. m and t m Let be the propagation constant and thickness of magnetic material layer 1.

[0040]

[0041] The A2B2C2D2 transfer matrix describes the metal structure and diodes in selectable layer 2, where jwL1 is the equivalent impedance of the metal structure; Z d Given the equivalent impedance of four diodes, Z is the impedance when a low-power electromagnetic wave is incident. d Equivalent to 1 / jwC1; When a high-power electromagnetic wave is incident, Z d Equivalent to R on .

[0042]

[0043] The A3B3C3D3 transfer matrix describes the dielectric substrate 3b in the selectable layer 2, where Z d β is the characteristic impedance of dielectric substrate 3b. d and t d Let be the propagation constant and thickness of the dielectric substrate 3b.

[0044]

[0045] The ABCD transmission matrix describes the low-pass, high-absorption energy-selective surface structure of this invention. Formulas for the transmission coefficient and reflection coefficient can be obtained from this matrix:

[0046]

[0047] Under ideal conditions, Z0 is air, and the impedance is 377Ω. With electromagnetic waves of different power incident on the diode, it exhibits different equivalent impedances: under low-power electromagnetic wave incident conditions, the diode acts as a cutoff capacitor; under high-power electromagnetic wave incident conditions, the diode acts as a conduction resistor. When the magnetic material layer is connected to a grounded metal plate of equal size, it exhibits reflection filtering characteristics at low frequencies and absorption filtering characteristics at high frequencies. By replacing the metal plate with the energy-selective layer, three different states can be obtained: operating state, stealth state, and protection state.

[0048] like Figure 5 As shown, under low-power electromagnetic wave incidence, the structure of this invention has a low-frequency passband of DC–1.06 GHz with an insertion loss below 3 dB. Simultaneously, it has a wide absorption band at high frequencies, with a bandwidth of 3.56–10.67 GHz exhibiting an absorption effect of over 90%, and a relative bandwidth of 99.9%.

[0049] like Figure 6 As shown, under the condition of high-power electromagnetic wave incident, the structure of the present invention has a shielding band with a shielding effectiveness of more than 25dB in the DC–0.75GHz range, and at the same time has a wide absorption band at high frequencies, with a wave absorption effect of more than 90% in the bandwidth of 2.37–7.87GHz and a relative bandwidth of 107.4%.

[0050] The specific structural parameters are described below:

[0051] Where p represents the length and width of the entire unit structure along the x and y axes, and also the length and width of the magnetic material layer 1, the selectable layer 2, and the dielectric substrate 3b. w1 represents the width of the first metal structure 1a and the fourth metal structure 2a, and w2 represents the length of the second metal structure 1d, the third metal structure 1e, the fifth metal structure 2d, and the sixth metal structure 2e. d1 and d2 represent the length and width of the first to eighth diodes (1b, 1c, 1f, 1g, 2b, 2c, 2f, 2g). l1 represents the length of the seventh metal structure 3a, and l2 represents the length of the first metal structure 1a and the fourth metal structure 2a. t d t represents the thickness of the dielectric substrate 3b. m denoted as the thickness of magnetic material layer 1.

[0052] Figure 7This is a scattering rate curve of the structure of this invention under low-power electromagnetic wave incident conditions. It can be seen that there is over 80% transmittance in the DC-0.5GHz frequency band, and over 50% (3dB) transmittance in the DC-1.1GHz frequency band; while there is over 80% absorption rate in the high-frequency 2.9-10.9GHz broadband; the overall reflectivity is below 20%, indicating good stealth characteristics.

[0053] Figure 8 This is a scattering rate curve of the structure of this invention under high-power electromagnetic wave incident conditions. It can be seen that the transmittance across the entire waveband is below 20%, indicating excellent shielding effectiveness; in the low-frequency DC-0.55GHz broadband, there is a reflectivity of over 50%, with most of the unreflected electromagnetic waves being absorbed by the magnetic material; in the high-frequency 1.75-8.2GHz broadband, there is an absorption rate of over 80%, demonstrating good stealth protection capabilities.

[0054] It can be seen that the results of this invention have a low insertion loss low-frequency passband at low power and an ultra-wide absorption band at high frequency; at high power, it has high shielding effectiveness at low frequency and still has a wide absorption band at high frequency.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, without departing from the principle of the present invention, changes in the material type / properties of the magnetic material layer and the energy selector layer, as well as the dielectric substrate and the diode, or changes in the structural form, size, and other improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-pass, high-absorption energy selective surface based on magnetic materials, comprising multiple periodically distributed units, characterized in that, Each unit consists of a bonded magnetic material layer and an energy selector layer, from top to bottom. The size of the magnetic material layer is the same as the unit size; The selectable layer includes: a dielectric substrate with the same size as the unit cell, and a first metal structure, a second metal structure, a third metal structure, a fourth metal structure, a fifth metal structure, a sixth metal structure, a seventh metal structure, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, and an eighth diode located on the upper surface of the dielectric substrate; wherein: One end of the first metal structure is connected to one end of the first diode and one end of the second diode, the other end of the first diode is connected to one end of the second metal structure, the other end of the second diode is connected to one end of the third metal structure, the other end of the second metal structure is connected to one end of the third diode, the other end of the third metal structure is connected to one end of the fourth diode, and the other ends of the third diode and the fourth diode are respectively connected to one end of the seventh metal structure. One end of the fourth metal structure is connected to one end of the fifth diode and one end of the sixth diode, respectively. The other end of the fifth diode is connected to one end of the fifth metal structure. The other end of the sixth diode is connected to one end of the sixth metal structure. The other end of the fifth metal structure is connected to one end of the seventh diode. The other end of the sixth metal structure is connected to one end of the eighth diode. The other ends of the seventh diode and the other ends of the eighth diode are respectively connected to the other end of the seventh metal structure. The first diode and the fifth diode are symmetrically arranged about the diagonal of the dielectric substrate; the second diode and the sixth diode are symmetrically arranged about the diagonal of the dielectric substrate; the third diode and the seventh diode are symmetrically arranged about the diagonal of the dielectric substrate; and the fourth diode and the eighth diode are symmetrically arranged about the diagonal of the dielectric substrate. The first metal structure and the fourth metal structure are symmetrically arranged about the diagonal of the dielectric substrate, the second metal structure and the fifth metal structure are symmetrically arranged about the diagonal of the dielectric substrate, the third metal structure and the sixth metal structure are symmetrically arranged about the diagonal of the dielectric substrate, and the seventh metal structure is symmetrical about the diagonal of the dielectric substrate.

2. The low-pass, high-absorption energy selective surface based on magnetic materials according to claim 1, characterized in that, A rectangular notch is provided at one corner of the seventh metal structure.

3. The low-pass, high-absorption energy selective surface based on magnetic materials according to claim 2, characterized in that, The side length of the seventh metal structure, after removing the rectangular notch, is the same as that of the first metal structure and the fourth metal structure.

4. The low-pass, high-absorption energy selective surface based on magnetic materials according to claim 1, characterized in that, The dielectric substrate used is Rogers RT5008.

5. The low-pass, high-absorption energy selective surface based on magnetic materials according to claim 1, characterized in that, The first, second, third, fourth, fifth, sixth, seventh, and eighth diodes are all SKYWORKS SMP1330.

6. The low-pass, high-absorption energy selective surface based on magnetic materials according to claim 1, characterized in that, The thickness ratio of the magnetic material layer to the selectable layer satisfies t m : t d =32:

5.

7. A low-pass, high-absorption energy selective surface based on magnetic materials according to any one of claims 1-6, characterized in that, The magnetic material layer is impedance matched with the energy selector layer, achieving a low passband with low insertion loss and a wide high-frequency absorption band under low power conditions, and a low-frequency reflection shielding band and a wide high-frequency absorption band under high power conditions.

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