Low-pass high-absorption energy selective surface based on magnetic material

Abstract

The invention discloses a low-pass high-absorption energy selection surface based on a magnetic material, which comprises a plurality of periodically distributed units, and each unit comprises a magnetic material layer and an energy selection layer which are tightly attached from top to bottom; wherein the selectable layer comprises a dielectric substrate, and first to seventh metal structures and first to eighth diodes which are arranged on the dielectric substrate. A complete loop is formed through a plurality of diodes, and through impedance matching between a magnetic material and an optional layer, when low-power electromagnetic waves are incident, a low-frequency passband with low insertion loss is realized, and an ultra-wide absorption band is realized at a high-frequency position; when high-power electromagnetic waves are incident, high shielding effectiveness is achieved in a working frequency band, and an ultra-wide absorption band is achieved outside the band. The device is simple in overall design structure, clear in principle, convenient to machine, low in cost and very wide in application prospect.

Description

Technical Field

[0001] The present 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 Art

[0002] Energy Selective Surface (ESS) consists of a frequency selective surface and a diode, and is usually used as a new type of electromagnetic protection technology. In an electromagnetic environment, if a low-power electromagnetic wave is incident on the electromagnetic surface of a periodic structure, it will selectively pass through the required electromagnetic wave band; if it is in an environment hit by a high-power electromagnetic wave, the diode on the electromagnetic surface will be excited to conduct to form a protective shielding feature, thereby reducing the interference and damage of electromagnetic pulses to electronic equipment, that is, achieving the effect of electromagnetic protection.

[0003] Frequency selective surfaces that pass electromagnetic waves within the working frequency band and absorb electromagnetic waves outside the working frequency band have important application needs in the fields of electromagnetic protection and electromagnetic stealth. At present, the main method used for out-of-band absorption is absorbing materials, and their structures are mostly based on metal backplanes to design absorbing characteristics. Compared with the method of absorbing waves by structure and resistance, absorbing materials are easy to design and process, and can achieve better absorbing effects.

[0004] At present, most of the common energy selective surfaces adopt a bandpass type structural design, while the band absorption type is usually only common in frequency selective surfaces, and there has been no report on the band absorption type energy selective surface; the bandpass type energy selective surface can obtain a passband when low-power electromagnetic waves are incident, and the outside of the band is a reflection band, and it is a reflection band when high-power electromagnetic waves are incident. These bandpass type energy selective surfaces lack research on stealth protection characteristics outside the working frequency band; and the design of the working frequency band mostly focuses on the medium and high frequencies, ignoring the importance of the low-frequency passband (VHF), and cannot meet the needs of low-frequency transmission and high-frequency absorption in practical applications. Summary of the invention

[0005] The purpose of the present invention is to provide a low-pass high-absorption energy selective surface based on magnetic materials in view of the deficiencies of the prior art. The structure realizes a low-frequency passband with low insertion loss and an ultra-wide absorption band at high frequencies by cascading and impedance matching a layer of magnetic material with a layer of energy selective surface when low-power electromagnetic waves are incident; when high-power electromagnetic waves are incident, a high shielding effectiveness is achieved within the working frequency band, and an ultra-wide absorption band is achieved outside the band. The overall design structure of the present invention is simple, the principle is clear, it is easy to process, the cost is low, and the application prospect is very broad.

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

[0007] The magnetic material layer comprises a piece of magnetic material, the size of which is the same as the unit size. The magnetic material layer is located above the selectable layer, and the two layers are seamlessly attached, with a thickness of t m Satisfy 0.03λ a ~ 0.05λ a , λ a The wavelength corresponding to the wave absorption starting frequency of the low-pass high-absorption energy selective surface structure based on magnetic materials of the present invention; 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. Among them: one end of the first metal structure is connected to one end of the first diode and one end of the second diode respectively, 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 end of the third diode and the other end of the fourth diode are respectively connected to one end of the seventh metal structure;

[0008] 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, and the other end of the seventh diode and the other end of 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 size of the dielectric substrate is the same as the unit size, and the thickness t d Satisfy 0.003λ a ~0.009λ a , λ a It is the wavelength corresponding to the wave absorption starting frequency of the low-pass high-absorption energy selective surface structure based on magnetic materials of the present invention.

[0009] Preferably, the magnetic material layer adopts a square structure and is seamlessly and closely attached to the energy selection layer below.

[0010] Preferably, the first diode and the fifth diode are symmetrically arranged about the diagonal line of the energy selectable layer, the second diode and the sixth diode are symmetrically arranged about the diagonal line of the energy selectable layer, the third diode and the seventh diode are symmetrically arranged about the diagonal line of the energy selectable layer, and the fourth diode and the eighth diode are symmetrically arranged about the diagonal line of the energy selectable layer.

[0011] Preferably, the first metal structure and the fourth metal structure are symmetrically arranged with respect to the diagonal line of the energy selectable layer, the second metal structure and the fifth metal structure are symmetrically arranged with respect to the diagonal line of the energy selectable layer, the third metal structure and the sixth metal structure are symmetrically arranged with respect to the diagonal line of the energy selectable layer, and the seventh metal structure is symmetrical with respect to the diagonal line of the energy selectable layer.

[0012] Preferably, the dielectric substrate uses Rogers RT5008 with a dielectric constant of 2.2.

[0013] Preferably, the first diode, the second diode, the third diode, the fourth diode, the fifth diode, the sixth diode, the seventh diode and the eighth diode are all SKYWORKS SMP1330.

[0014] Preferably, the thickness ratio of the magnetic material layer to the selectable layer is 32:5.

[0015] Preferably, the magnetic material layer is impedance matched with the energy selective layer, thereby achieving a low passband with low insertion loss and a wider high-frequency absorption band under low power conditions, and a higher shielding effectiveness in the operating frequency band and a wider high-frequency absorption band under high power conditions.

[0016] Specific working principle: When low-power electromagnetic waves are incident, the eight diodes in the energy-selective layer are in the off state, and the diodes at this time can be equivalent to a cut-off capacitor. Then the energy-selective layer can be equivalent to an LC series structure, showing a filtering characteristic of low-frequency transmission and high-frequency reflection, and then through the impedance matching of the magnetic material layer, a low-frequency transmission band can be obtained at low frequencies, and the high frequency will show the effect of an absorber, which can absorb broadband waves.

[0017] When a high-power electromagnetic wave is incident, the eight diodes in the energy-selective layer are in the on state, and the diodes at this time can be equivalent to an on-resistance. Then the energy-selective layer can be equivalent to an inductive structure (the on-resistance is extremely small and negligible), and the overall performance is a filtering characteristic of full-band reflection. Then, through the impedance matching of the magnetic material layer, a reflection band with higher shielding efficiency can be obtained at low frequencies, and at high frequencies, it presents the effect of an absorber like low power, and can perform broadband absorption. The energy-selective layer is equipped with eight diodes to avoid the introduction of an absorbing structure that causes the complete circuit to be unable to be normally conducted, and does not cause an unsatisfactory electromagnetic response.

[0018] Compared with the prior art, the low-pass high-absorption energy selective surface based on magnetic material of the present invention has the following advantages: (1) The present invention is based on a two-layer structure and is designed to have a low-frequency transmission band and a high-frequency absorption band in low-power conditions, and a low-frequency reflection shielding band and a high-frequency absorption band in high-power conditions. By matching the impedance between the energy-selective layer and the magnetic material layer, the stealth and protection performance of the work are improved.

[0019] (2) The low-pass high-absorption energy selective surface provided by the present invention adopts a simple unit structure, efficiently utilizes the state of electromagnetic waves of the diode at different powers, and achieves a good impedance matching effect. The design principle is very clear and has a good guiding significance for this type of work, filling the gap in this type of work in energy selective surfaces. The design structure is very simple and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a three-dimensional structural unit of a low-pass high-absorption energy selective surface based on magnetic materials of the present invention.

[0021] Figure 2 It is a top view of an energy selection layer of a low-pass high-absorption energy selection surface based on magnetic materials according to the present invention.

[0022] Figure 3 It is a front view of a low-pass high-absorption energy selection surface based on magnetic material of the present invention.

[0023] Figure 4 It is a schematic diagram of an equivalent circuit of a low-pass high-absorption energy selective surface based on magnetic materials of the present invention.

[0024] Figure 5 It is a scattering characteristic curve diagram of a low-pass high-absorption energy selective surface based on magnetic material under irradiation with low-power incident electromagnetic waves of the present invention.

[0025] Figure 6It is a scattering characteristic curve diagram of a low-pass high-absorption energy selective surface based on magnetic material under irradiation with high-power incident electromagnetic waves of the present invention.

[0026] Figure 7 This is a comparison diagram of the scattering rates of a low-pass high-absorption energy selective surface based on magnetic materials under irradiation with low-power incident electromagnetic waves of the present invention.

[0027] Figure 8 This is a comparison diagram of the scattering rates of a low-pass high-absorption energy selective surface based on magnetic materials under irradiation with high-power incident electromagnetic waves of the present invention.

[0028] Markings in the figure: 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 DESCRIPTION

[0029] The present invention is further analyzed below in conjunction with specific embodiments.

[0030] like Figure 1 As shown, a low-pass high-absorption energy selective surface based on magnetic material has a vertically arranged structure, including periodically distributed and seamlessly covered units, and each unit includes a magnetic material layer 1 and an energy selective layer 2 from top to bottom.

[0031] like Figure 2As shown, the energy selection 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 through the first diode 1b and the second diode 1c respectively, and the second metal structure 1d and the third metal structure 1e are connected to the seventh metal structure 3a through 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 through the fifth diode 2b and the sixth diode 2c respectively, and the fifth metal structure 2d and the sixth metal structure 2e are connected to the seventh metal structure 3a through 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 size of the dielectric substrate 3b is the same as the unit size and the dielectric substrate used is 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's SMP1330.

[0032] like Figure 3 As shown, the magnetic material layer 1 includes a piece of 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, and the two layers are seamlessly bonded.

[0033] like Figure 4 As shown, the low-pass high-absorption energy selective surface based on magnetic material of the present invention can be equivalent to a specific circuit model. The magnetic material layer 1 can be equivalent to a characteristic impedance of Z m The lossy transmission line, where β m and t m is the propagation constant and thickness of the magnetic material layer 1; the first metal structure 1a, the second metal structure 1d, the third metal structure 1e, the fourth metal structure 2a, the fifth metal structure 2d, the sixth metal structure 2e and the seventh metal structure 3a in the energy-selective layer 2 can be equivalent to an inductor L 1 , the first diode 1b and the fifth diode 2b can be equivalent to a diode D 3 , the second diode 1c and the sixth diode 2c can be equivalent to a diode D 1 The third diode 1f and the seventh diode 2f can be equivalent to a diode D4 , the fourth diode 1g and the eighth diode 2g can be equivalent to a diode D 2 ; The dielectric substrate 3b can be equivalent to a characteristic impedance of Z d The lossy transmission line, where β d and t d is the propagation constant and thickness of the dielectric substrate 3b;

[0034] According to the equivalent circuit model, the ABCD transmission matrix of the magnetic material layer 1, the energy selection layer 2, and the dielectric substrate 3b can be obtained respectively: A 1 B 1 C 1 D 1 The transmission matrix describes a layer of magnetic material 1, where Z m is the characteristic impedance of the magnetic material, β m and t m are the propagation constant and thickness of the magnetic material layer 1.

[0035] A 2 B 2 C 2 D 2 The transfer matrix describes the metal structures and diodes in the energy-selective layer 2, where jwL 1 is the equivalent impedance of the metal structure; Z d is the equivalent impedance of the four diodes. When a low-power electromagnetic wave is incident, Z d Equivalent to 1 / jwC 1 ; When high power electromagnetic wave is incident, Z d Equivalent to R on .

[0036] A 3 B 3 C 3 D 3 The transmission matrix describes the dielectric substrate 3b in the energy-selective layer 2, where Z d is the characteristic impedance of the dielectric substrate 3b, β d and t d are the propagation constant and thickness of the dielectric substrate 3b.

[0037] The ABCD transmission matrix describes the low-pass high-absorption energy selective surface structure of the present invention. According to the matrix, the formulas of transmission coefficient and reflection coefficient can be obtained: Under ideal conditions, Z 0 The impedance is 377Ω for air. With the incident electromagnetic waves of different powers, the diode will show different equivalent impedances, that is, in the case of low-power electromagnetic waves, the diode behaves as a cut-off capacitor; in the case of high-power electromagnetic waves, the diode behaves as an on-resistance. When the magnetic material layer is connected to an equal-sized grounded metal plate, it exhibits a reflective filtering characteristic at low frequencies and an absorbing filtering characteristic at high frequencies. By replacing the metal plate with the energy-selective layer, three different states can be obtained, namely, the working state, the stealth state, and the protection state.

[0038] like Figure 5 As shown, it can be seen that under the condition of low-power electromagnetic wave incidence, the structure of the present invention has a low-frequency passband of DC-1.06GHz with an insertion loss below 3dB. At the same time, there is a wider absorption band at high frequencies, with a bandwidth of more than 90% absorbing effect in the range of 3.56-10.67GHz, and a relative bandwidth of 99.9%.

[0039] like Figure 6 As shown, it can be seen that in the case of high-power electromagnetic wave incidence, the structure of the present invention has a shielding effectiveness protection band of more than 25dB in the range of DC-0.75GHz, and at the same time has a wider absorption band at high frequencies, with a bandwidth of more than 90% absorbing effect in the range of 2.37-7.87GHz, and a relative bandwidth of 107.4%.

[0040] The specific structural parameters are described as follows: Where p is the length and width of the entire unit structure in the x-axis and y-axis directions, and is also the length and width of the magnetic material layer 1, the selectable layer 2 and the dielectric substrate 3b. 1 is the width of the first metal structure 1a and the fourth metal structure 2a, w 2 is the length of the second metal structure 1d, the third metal structure 1e, the fifth metal structure 2d and the sixth metal structure 2e. 1 and d 2 are the length and width of the first to eighth diodes (1b, 1c, 1f, 1g, 2b, 2c, 2f, 2g). 1 is the length of the seventh metal structure 3a, l 2 is the length of the first metal structure 1a and the fourth metal structure 2a. d is the thickness of the dielectric substrate 3b, t m is the thickness of the magnetic material layer 1.

[0041] Figure 7This is a scattering rate curve of the structure of the present invention under low-power electromagnetic wave incidence. It can be seen that the transmittance is more than 80% in the DC-0.5GHz frequency band, and more than 50% (3dB) in the DC-1.1GHz frequency band; and the absorption rate is more than 80% in the high-frequency 2.9-10.9GHz broadband; the reflectivity of the entire band is less than 20%, indicating that it has good stealth characteristics.

[0042] Figure 8 This is a scattering rate curve of the structure of the present invention under high-power electromagnetic wave incidence. It can be seen that the transmittance of the entire band is below 20%, indicating that it has good shielding effectiveness; in the low-frequency DC-0.55GHz broadband, there is a reflectivity of more than 50%, and most of the remaining electromagnetic waves that are not reflected are absorbed by the magnetic material; in the high-frequency 1.75-8.2GHz broadband, there is an absorption rate of more than 80%, which has good stealth protection function.

[0043] It can be seen that the invention has a low insertion loss low-frequency passband at low power and an ultra-wide absorption band at high frequency; it has higher shielding effectiveness at low frequency at high power and still has a wider absorption band at high frequency.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, by replacing the material type / properties of the magnetic material layer and the selectable layer, the dielectric substrate and the diode, or changing the structural form and size, as well as other improvements and modifications, these improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-pass high-absorption energy selective surface based on magnetic materials, comprising a plurality of periodically distributed units, characterized in that: Each unit includes a laminated magnetic material layer and an energy selective layer from top to bottom; The size of the magnetic material layer is the same as the unit size; The selectable layer comprises: a dielectric substrate having the same size as the unit size, 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 respectively, 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 end of the third diode and the other end of 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, and the other end of the seventh diode and the other end of the eighth diode are respectively connected to the other end of the seventh metal structure.

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

3. A low-pass high-absorption energy selective surface based on magnetic material according to claim 2, characterized in that: The side length of the seventh metal structure, excluding the rectangular notch, is equal to that of the first metal structure and the fourth metal structure.

4. The low-pass high-absorption energy selective surface based on magnetic material according to claim 1, characterized in that: The first diode and the fifth diode are symmetrically arranged with respect to the diagonal line of the dielectric substrate, the second diode and the sixth diode are symmetrically arranged with respect to the diagonal line of the dielectric substrate, the third diode and the seventh diode are symmetrically arranged with respect to the diagonal line of the dielectric substrate, and the fourth diode and the eighth diode are symmetrically arranged with respect to the diagonal line of the dielectric substrate.

5. The low-pass high-absorption energy selective surface based on magnetic material according to claim 1, characterized in that: The first metal structure and the fourth metal structure are symmetrically arranged with respect to the diagonal line of the dielectric substrate, the second metal structure and the fifth metal structure are symmetrically arranged with respect to the diagonal line of the dielectric substrate, the third metal structure and the sixth metal structure are symmetrically arranged with respect to the diagonal line of the dielectric substrate, and the seventh metal structure is symmetrical with respect to the diagonal line of the dielectric substrate.

6. The low-pass high-absorption energy selective surface based on magnetic material according to claim 1, characterized in that: The medium used in the dielectric substrate is Rogers RT5008.

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

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

5.

9. A low-pass high-absorption energy selective surface based on magnetic material according to any one of claims 1 to 8, characterized in that: The magnetic material layer is impedance matched with the energy selectable layer, thereby realizing 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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