Low-pass high-absorption energy selective surface based on zigzag structure

Abstract

The invention discloses a zigzag structure-based low-pass high-absorption energy selection surface, which comprises a plurality of periodically distributed units, each unit sequentially comprises a frequency selection layer, a dielectric layer and an energy selection layer from top to bottom, the frequency selection layer comprises a first dielectric substrate and a plurality of metal zigzag structures and resistors on the upper surface and the lower surface of the first dielectric substrate, and the metal zigzag structures and the resistors are arranged on the upper surface and the lower surface of the first dielectric substrate. The selectable layer comprises a second dielectric substrate, and a plurality of metal block structures and diodes on the upper surface of the second dielectric substrate; and the frequency selection layer and the selectable layer are separated by the dielectric layer. The energy selection surface and the frequency selection surface are matched in impedance through the dielectric layer, so that when low-power electromagnetic waves are incident, a low-frequency passband with low insertion loss is realized, and a relatively wide absorption frequency band is formed outside the passband; and when high-power electromagnetic waves are incident, a reflection frequency band with relatively high shielding effectiveness is realized in a working frequency band, and a relatively wide absorption frequency band is formed outside the band. The device is simple and clear in overall design structure principle and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic protection and relates to a low-pass high-absorption energy selection surface based on a zigzag structure. Background Art

[0002] In complex electromagnetic environments, the Energy Selective Surface (ESS) is an important and practical periodic electromagnetic surface for dealing with high-power environments. The components of the ESS mainly include the frequency selective surface and the diode. Through the impedance transformation of the diode at different powers, the working state and the protection state can be generated.

[0003] There are many types of frequency selective surfaces in terms of working states: bandpass, low-pass, wave absorption, polarization conversion, etc. Wave absorption is of great significance for electromagnetic protection and stealth. The addition of stealth bands has a great effect on electromagnetic equipment under low-power electromagnetic wave incidence. If it can be both shielded and invisible under high-power electromagnetic wave incidence, it can greatly expand the research direction of energy selective surfaces and meet the needs of practical applications. Wave absorption is usually achieved through two methods: absorbing materials and resonant structures. The resonant structure can obtain absorbing frequency bands of any band by designing different structures and resistors. Compared with absorbing materials, its design principle is clearer and the processing cost is not high, so it is more suitable for practical applications.

[0004] However, most of the energy selective surfaces reported so far target the working frequency band and the protection frequency band, and there is very little research on the stealth frequency band in the frequency selective surfaces. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and to provide a low-pass, high-absorption energy selective surface based on a tortuous structure. The structure cascades and impedance matches the energy selective surface and the frequency selective surface with the dielectric layer. When a low-power electromagnetic wave is incident, a low-frequency passband with low insertion loss is achieved, and a wider absorbing frequency band is formed outside the band; when a high-power electromagnetic wave is incident, a low-frequency reflection band with higher shielding effectiveness is achieved, and a wider absorbing frequency band is formed outside the band.

[0006] The low-pass high-absorption energy selective surface based on a zigzag structure of the present invention is a vertically arranged structure, and the structure is a periodically distributed (seamlessly arranged in two periodic directions of x and y) unit, each unit from top to bottom includes a frequency selective layer, a dielectric layer, and an energy selective layer connected in sequence.

[0007] The frequency selective layer includes a first dielectric substrate; A first metal zigzag structure, a second metal zigzag structure, a third metal zigzag structure, a fourth metal zigzag structure, a first resistor, a second resistor, a third resistor, and a fourth resistor are provided on the upper surface of the first dielectric substrate; the first metal zigzag structure, the second metal zigzag structure, the third metal zigzag structure, and the fourth metal zigzag structure have the same structure, and all include two metal edges and three metal wires, the two metal edges are vertically arranged, and the three metal wires extend perpendicularly to one of the metal edges toward the center of the first dielectric substrate; one metal edge of the first metal zigzag structure is connected to one metal edge of the second metal zigzag structure through a first resistor, another metal edge of the second metal zigzag structure is connected to one metal edge of the third metal zigzag structure through a second resistor, another metal edge of the third metal zigzag structure is connected to one metal edge of the fourth metal zigzag structure through a third resistor, and another metal edge of the fourth metal zigzag structure is connected to another metal edge of the first metal zigzag structure through a fourth resistor; A fifth metal zigzag structure, a sixth metal zigzag structure, a seventh metal zigzag structure, an eighth metal zigzag structure, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor are arranged on the lower surface of the first dielectric substrate; the fifth metal zigzag structure, the sixth metal zigzag structure, the seventh metal zigzag structure and the eighth metal zigzag structure have the same structure and are all in a continuous "bow" shape; one end of the fifth metal zigzag structure is connected to one end of the sixth metal zigzag structure through a fifth resistor, the other end of the sixth metal zigzag structure is connected to one end of the seventh metal zigzag structure through a sixth resistor, the other end of the seventh metal zigzag structure is connected to one end of the eighth metal zigzag structure through a seventh resistor, and the other end of the eighth metal zigzag structure is connected to the other end of the fifth metal zigzag structure through an eighth resistor; the size of the first dielectric substrate is the same as the unit size, and the thickness t d1 Satisfy 0.005λ L ~ 0.008λ L , λ a is the wavelength corresponding to the starting frequency of wave absorption of the structure.

[0008] The energy selectable layer includes a second dielectric substrate and a first metal block structure, a second metal block structure, a third metal block structure, a fourth metal block structure, a fifth metal block structure, a sixth metal block structure, a seventh metal block 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 thereof. One end of the first metal block structure is connected to one end of the second metal block structure and one end of the third metal block structure respectively through the first diode and the second diode, and the other end of the second metal block structure and the other end of the third metal block structure are connected to one end of the seventh metal block structure respectively through the third diode and the fourth diode;

[0009] One end of the fourth metal block structure is connected to one end of the fifth metal block structure and one end of the sixth metal block structure through a fifth diode and a sixth diode, respectively; the other end of the second metal block structure and the other end of the third metal block structure are connected to one end of the seventh metal block structure through a third diode and a fourth diode, respectively; a rectangular notch is provided at the upper left corner of the seventh metal block structure; the size of the second dielectric substrate is the same as the unit size, and the thickness is t d2 Satisfy 0.005λ a ~ 0.008λ a , λ a is the wavelength corresponding to the starting frequency of wave absorption of the structure.

[0010] The size of the dielectric layer is the same as the unit size; the thickness of the dielectric layer is t a Satisfy 0.01λ a ~ 0.03λ a ,λ a It is the wavelength corresponding to the starting frequency of wave absorption of the structure; the dielectric layer plays the role of impedance matching for the frequency selective layer and the energy selective layer.

[0011] Preferably, the width of the metal edges and metal lines in the first metal zigzag structure, the second metal zigzag structure, the third metal zigzag structure, and the fourth metal zigzag structure is smaller than the width of the metal edges and metal lines in the fifth metal zigzag structure, the sixth metal zigzag structure, the seventh metal zigzag structure, and the eighth metal zigzag structure. This is because the metal zigzag structure on the upper surface and the metal zigzag structure on the lower surface produce two resonance points, the metal zigzag structure with a smaller width produces a larger inductance, and the metal zigzag structure with a larger width produces a smaller inductance, and coupling capacitance is generated between the metal lines in the periodic unit, and the inductance and capacitance resonate; therefore, in order to have different resonance points, the widths of the metal zigzag structures on the upper and lower surfaces are inconsistent.

[0012] Preferably, the first to fourth metal meandering structures are arranged to be rotated 45° about the center of the frequency selective layer.

[0013] Preferably, the fifth to eighth metal zigzag structures are arranged to be rotated 45° about the center of the frequency selective layer.

[0014] Preferably, the first to fourth resistors are arranged with a rotation of 45° about the center of the frequency selective layer.

[0015] Preferably, the fifth to eighth resistors are arranged to be rotated 45° with respect to the center of the frequency selective layer.

[0016] 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.

[0017] Preferably, the first metal block structure and the fourth metal block structure are symmetrically arranged about the diagonal of the energy selectable layer, the second metal block structure and the fifth metal block structure are symmetrically arranged about the diagonal of the energy selectable layer, the third metal block structure and the sixth metal block structure are symmetrically arranged about the diagonal of the energy selectable layer, and the seventh metal block structure is symmetrical about the diagonal of the energy selectable layer.

[0018] Preferably, the medium used in the medium layer is air.

[0019] Preferably, the dielectric used in the first dielectric substrate and the second dielectric substrate is Rogers RT5008 with a dielectric constant of 2.2.

[0020] Preferably, the first resistor, the second resistor, the third resistor and the fourth resistor are all resistors with a resistance value of 400Ω.

[0021] Preferably, the fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor are all resistors with a resistance value of 600Ω.

[0022] 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.

[0023] Preferably, the thickness ratio of the first dielectric substrate to the second dielectric substrate is 1:1.

[0024] Preferably, the thickness ratio of the first (or second) dielectric substrate to the dielectric layer is 1:20.

[0025] Preferably, the frequency selective layer and the energy selective layer are impedance matched through a dielectric layer, thereby realizing a low-frequency passband with low insertion loss and a wider high-frequency absorption band outside the band when low-power electromagnetic waves are incident, and a low-frequency reflection band with higher shielding effectiveness and a wider high-frequency absorption band outside the band when high-power electromagnetic waves are incident.

[0026] Specific working principle: When high and low electromagnetic waves are incident, the metal zigzag structures on the upper and lower surfaces of the frequency selection layer are equivalent to large inductance and small inductance respectively, and coupling capacitance will be generated between the metal zigzag structures in the periodic unit, that is, large capacitance and small capacitance will be generated on the upper and lower surfaces respectively, and then the overall frequency selection layer can be equivalent to two RLC parallel structures through the series connection of resistors; when a metal back plate is added to the frequency selection layer, it will show the performance of an absorber, that is, a filtering characteristic of low-frequency reflection and high-frequency absorption. In order to realize a low-pass high-absorption type energy selection surface, the energy selection layer replaces the metal back plate and then matches it through the dielectric layer.

[0027] When low-power electromagnetic waves are incident, the eight diodes in the energy selection layer are in the off state, and the diodes at this time can be equivalent to a cut-off capacitor. Then the energy selection layer can be equivalent to an LC series structure, showing a filtering characteristic of low-frequency transmission and high-frequency reflection; then the frequency selection layer forms a broadband absorber at high frequencies by impedance matching of the dielectric layer and utilizing the high-frequency reflection characteristics of the energy selection layer. At low frequencies, the intermediate frequency selection layer and the energy selection layer both show low-frequency transmission characteristics, that is, a transmission band can be obtained at low frequencies, and broadband absorption can be performed at high frequencies. The energy selection layer is provided with eight diodes because the preferred diodes cannot form a complete circuit in the case of a single number, which will cause the structure to fail to present the required state.

[0028] When high-power electromagnetic waves are 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 entire frequency band presents a reflection filtering characteristic. Then, the frequency-selective layer obtains a high shielding efficiency reflection band at low frequencies through impedance matching of the dielectric layer, and obtains a wider wave absorption bandwidth at high frequencies by utilizing the reflection characteristics of the energy-selective layer.

[0029] Compared with the prior art, the low-pass high-absorption energy selective surface based on a tortuous structure of the present invention has the following advantages: (1) The present invention is based on a three-layer structure to obtain a low-insertion-loss low-frequency passband and a wide-band absorption band outside the band under low-power electromagnetic wave incidence conditions, and to obtain a reflection band with higher shielding effectiveness and a wide-band absorption band outside the band under high-power electromagnetic wave incidence conditions. The upper surface of the frequency-selective layer adopts a plurality of slender metal meander lines, and the lower surface adopts a plurality of thick and long metal meander lines, thereby providing more inductance and effectively reducing the size of the unit. The working absorption bandwidth and protection performance are improved by impedance matching between the frequency-selective layer and the energy-selective layer and the dielectric layer.

[0030] (2) The present invention provides a low-pass high-absorption energy selective surface based on a tortuous structure, which combines the energy selective surface with the absorber, efficiently utilizes the performance of both, achieves a good impedance matching effect, provides a clear principle, and provides ideas for the blank of such work. It can be applied to stealth technology, radar technology, protection technology and electromagnetic interference suppression and other protection fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of a three-dimensional structural unit of a low-pass high-absorption energy selective surface based on a tortuous structure of the present invention; Figure 2 It is a top view of the upper surface of the frequency selection layer of a low-pass high-absorption energy selection surface based on a zigzag structure of the present invention; Figure 3 It is a top view of the lower surface of the frequency selection layer of a low-pass high-absorption energy selection surface based on a zigzag structure of the present invention; Figure 4 It is a top view of an energy selection layer of a low-pass high-absorption energy selection surface based on a tortuous structure of the present invention; Figure 5 It is a front view of a low-pass high-absorption type energy selection surface based on a zigzag structure of the present invention; Figure 6 It is a schematic diagram of an equivalent circuit of a low-pass high-absorption energy selective surface based on a zigzag structure of the present invention; Figure 7 It is a scattering characteristic curve diagram of a low-pass high-absorption type energy selective surface based on a tortuous structure of the present invention under irradiation with a low-power incident electromagnetic wave; Figure 8 It is a scattering characteristic curve diagram of a low-pass high-absorption type energy selective surface based on a tortuous structure of the present invention under irradiation with a high-power incident electromagnetic wave; Fig. 9 It is a comparison diagram of the scattering rate of a low-pass high-absorption type energy selective surface based on a tortuous structure of the present invention when irradiated with a low-power incident electromagnetic wave; Fig.10It is a comparison diagram of the scattering rate of a low-pass high-absorption type energy selective surface based on a tortuous structure of the present invention under irradiation with a high-power incident electromagnetic wave; Markings in the figure: frequency selective layer 1, dielectric layer 2, energy selective layer 3, first dielectric substrate 1a, first metal zigzag structure 1b, second metal zigzag structure 1c, third metal zigzag structure 1d, fourth metal zigzag structure 1e, first resistor 1f, second resistor 1g, third resistor 1h, fourth resistor 1i, second dielectric substrate 2a, fifth metal zigzag structure 2b, sixth metal zigzag structure 2c, seventh metal zigzag structure 2d, eighth metal zigzag structure 2e, fifth resistor 2f, sixth resistor 2g, seventh resistor 2h, eighth resistor 2i, first metal block structure 3a, second metal block structure 3b, third metal block structure 3c, fourth metal block structure 3d, fifth metal block structure 3e, sixth metal block structure 3f, seventh metal block structure 3g, first diode 4a, second diode 4b, third diode 4c, fourth diode 4d, fifth diode 4e, sixth diode 4f, seventh diode 4g, eighth diode 4h. DETAILED DESCRIPTION

[0032] The present invention is further analyzed below in conjunction with specific embodiments.

[0033] like Figure 1 As shown, a low-pass high-absorption energy selective surface based on a tortuous structure has a vertically arranged structure, including periodically distributed and seamlessly covered units, and each unit includes a frequency selective layer 1, a dielectric layer 2, and an energy selective layer 3 from top to bottom.

[0034] like Figure 2 As shown, the upper surface of the frequency selection layer 1 includes a first dielectric substrate 1a and a first metal meandering structure 1b, a second metal meandering structure 1c, a third metal meandering structure 1d, a fourth metal meandering structure 1e, a first resistor 1f, a second resistor 1g, a third resistor 1h, and a fourth resistor 1i located on the upper surface thereof; the first to fourth metal meandering structures (1b, 1c, 1d, 1e) are composed of three thin meandering metal wires; the first to fourth metal meandering structures (1b, 1c, 1d, 1e) are connected by the first to fourth resistors (1f, 1g, 1h, 1i); the size of the first dielectric substrate 1a is the same as the unit size. The resistance value of the first to fourth resistors (1f, 1g, 1h, 1i) is 400Ω.

[0035] like Figure 3As shown, the lower surface of the frequency selection layer 1 includes a first dielectric substrate 1a and a fifth metal meandering structure 2b, a sixth metal meandering structure 2c, a seventh metal meandering structure 2d, an eighth metal meandering structure 2e, a fifth resistor 2f, a sixth resistor 2g, a seventh resistor 2h, and an eighth resistor 2i located on the lower surface thereof; the fifth to eighth metal meandering structures (2b, 2c, 2d, 2e) are composed of two thick meandering metal wires; the fifth to eighth metal meandering structures (2b, 2c, 2d, 2e) are connected by the fifth to eighth resistors (2f, 2g, 2h, 2i); the size of the first dielectric substrate 1a is the same as the unit size. The resistance value of the fifth to eighth resistors (2f, 2g, 2h, 2i) is 600Ω.

[0036] like Figure 4 As shown, the energy selection layer 3 includes a second dielectric substrate 2a and a first metal block structure 3a, a second metal block structure 3b, a third metal block structure 3c, a fourth metal block structure 3d, a fifth metal block structure 3e, a sixth metal block structure 3f, a seventh metal block structure 3g, a first diode 4a, a second diode 4b, a third diode 4c, a fourth diode 4d, a fifth diode 4e, a sixth diode 4f, a seventh diode 4g, and an eighth diode 4h located on the upper surface thereof. The lower side of the first metal block structure 3a is connected to the second metal block structure 3b and the third metal block structure 3c through the first diode 4a and the second diode 4b respectively, and the second metal block structure 3b and the third metal block structure 3c are connected to the seventh metal block structure 3g through the third diode 4c and the fourth diode 4d respectively; the right side of the fourth metal block structure 3d is connected to the fifth metal block structure 3e and the sixth metal block structure 3f through the fifth diode 4e and the sixth diode 4f respectively, and the fifth metal block structure 3e and the sixth metal block structure 3f are connected to the seventh metal block structure 3g through the seventh diode 4g and the eighth diode 4h respectively; a rectangular notch is provided in the upper left corner of the seventh metal block structure 3g; the size of the second dielectric substrate 2a is the same as the unit size and the dielectric substrate used is Rogers RT5008 with a dielectric constant of 2.2; the first to eighth diodes (4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h) all use SKYWORKS's SMP1330.

[0037] like Figure 5 As shown, the medium used in the dielectric layer 2 is air, and its size is the same as the unit size; the dielectric layer 2 is located between the frequency selection layer 1 and the energy selection layer 3.

[0038] like Figure 6 As shown, a low-pass high-absorption energy selective surface based on a zigzag structure of the present invention can be equivalent to a specific circuit model.

[0039] The first metal zigzag structure 1b, the second metal zigzag structure 1c, the third metal zigzag structure 1d, and the fourth metal zigzag structure 1e on the upper surface of the frequency selection layer 1 can be equivalent to an inductor L1; the first resistor 1f, the second resistor 1g, the third resistor 1h, and the fourth resistor 1i can be equivalent to a resistor R1; since the structure is a periodic unit, the first to fourth metal zigzag structures (1b, 1c, 1d, 1e) between the units will have an equivalent coupling capacitor C1; the fifth metal zigzag structure 2b, the sixth metal zigzag structure 2c, the seventh metal zigzag structure 2d, and the eighth metal zigzag structure 2e on the lower surface of the frequency selection layer 1 can be equivalent to an inductor L2; the fifth resistor 2f, the sixth resistor 2g, the seventh resistor 2h, and the eighth resistor 2i can be equivalent to a resistor R2; since the structure is a periodic unit, the fifth to eighth metal zigzag structures (2b, 2c, 2d, 2e) between the units will have an equivalent coupling capacitor C2; the first dielectric substrate 1a in the frequency selection layer 1 can be equivalent to a dielectric substrate with a characteristic impedance of Z d1 The lossy transmission line, where β d1 and t d1 are the propagation constant and thickness of the first dielectric substrate 1a; The dielectric layer 2 can be equivalent to a characteristic impedance of Z a (medium is air) lossless transmission line, where β a and t a is the propagation constant and thickness of dielectric layer 2; The first metal block structure 3a, the second metal block structure 3b, the third metal block structure 3c, the fourth metal block structure 3d, the fifth metal block structure 3e, the sixth metal block structure 3f, and the seventh metal block structure 3g in the energy-selective layer 3 can be equivalent to an inductor L3; the first diode 4a and the fifth diode 4e can be equivalent to a diode D3, the second diode 4b and the sixth diode 4f can be equivalent to a diode D1, the third diode 4c and the seventh diode 4g can be equivalent to a diode D4, and the fourth diode 4d and the eighth diode 4h can be equivalent to a diode D2; the second dielectric substrate 2a can be equivalent to a dielectric substrate with a characteristic impedance Z d2 The lossy transmission line, where β d2 and t d2 are the propagation constant and thickness of the second dielectric substrate 2a.

[0040] According to the equivalent circuit model, the ABCD transmission matrices of the frequency selective layer 1, dielectric layer 2, and energy selective layer 3 can be obtained respectively: The A1B1C1D1 transmission matrix describes the frequency selective layer 1, where Z1 is the impedance of the upper surface of the frequency selective layer 1 (Z1=jwL1+1 / jwC1+R1), and Z2 is the impedance of the lower surface of the frequency selective layer 1 (Z2=jwL2+1 / jwC2+R2);d1 , β d1 and t d1 are the characteristic impedance, propagation constant and thickness of the first dielectric substrate 1a.

[0041] The A2B2C2D2 transmission matrix describes the dielectric layer 2, where β a and t a is the propagation constant and thickness of dielectric layer 2, the characteristic impedance Z of dielectric layer 2 (preferably air) a It is 377Ω.

[0042] The A3B3C3D3 transmission matrix describes the energy-selective layer 3, where Z3 is the impedance of the surface of the energy-selective layer 3 (Z3=jwL3+Z D ); Z D is the equivalent impedance of the diode; Z d2 , β d2 and t d2 are the characteristic impedance, propagation constant and thickness of the second dielectric substrate 2a.

[0043] The ABCD transmission matrix describes a low-pass high-absorption energy selective surface based on a tortuous structure of the present invention. According to the matrix, the formulas of reflection coefficient and transmission coefficient can be obtained: Under ideal conditions, Z0 is air with an impedance of 377Ω. When low-power electromagnetic waves are incident, the diode is equivalent to a cut-off capacitor; when high-power electromagnetic waves are incident, the diode is equivalent to an on-resistance. Three different states can be obtained through the equivalent circuit and the change of impedance, namely, working state, stealth state and protection state.

[0044] like Figure 7 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-1.7GHz 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 3.9-8.87GHz, and a relative bandwidth of 77.8%.

[0045] like Figure 8 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-0.89GHz, 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 2.49-8.73GHz, and a relative bandwidth of 111.2%.

[0046] The specific structural parameters are described as follows: Where p is the length and width of the entire unit structure in the x- and y-axis directions, and is also the length and width of the frequency-selective layer 1, the dielectric layer 2, the energy-selective layer 3, the first dielectric substrate 1a, and the second dielectric substrate 2a. w1 and l1 are the width and length of the first to fourth metal meander structures (1b, 1c, 1d, 1e), and w2 and w3 are the length and width of the thin meander line. w4 and l2 are the width and length of the fifth to eighth metal meander structures (2b, 2c, 2d, 2e), and w5 and w6 are the length and width of the thick meander line. r1 and r2 are the lengths of the first to fourth resistors (1f, 1g, 1h, 1i) and the fifth to eighth resistors (2f, 2g, 2h, 2i). l4 and w8 are the length and width of the first metal block structure 3a and the fourth metal block structure 3d, and l3 and w7 are the width and length of the second to third / fifth to sixth metal block structures (3b, 3c, 3e, 3f) and the seventh metal block structure 3g. d1 and d2 are the length and width of the first to eighth diodes (4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h). d1 is the thickness of the first dielectric substrate 1a, t a2 is the thickness of dielectric layer 2, t d2 is the thickness of the second dielectric substrate 2a.

[0047] Fig. 9 The following is a comparison of the scattering rate characteristic curves of the structure under low-power electromagnetic wave incidence. It can be seen that the transmittance is more than 80% in the DC-0.7GHz frequency band, and more than 50% (3dB) in the DC-1.7GHz frequency band; and the absorption rate is more than 80% in the high-frequency 3.7-9.1GHz broadband; except for the band from the passband to the absorption band, its reflectivity is less than 10%, indicating that it has good stealth characteristics outside the band.

[0048] Fig.10 This is a comparison of the scattering rate characteristic curves of the structure under high-power electromagnetic wave incidence. It can be seen that the transmittance in the DC-8GHz band is almost below 5%, indicating that it has excellent shielding effectiveness; in the low-frequency DC-1.8GHz broadband, the reflectivity is more than 50%, and most of the remaining electromagnetic waves that are not reflected are absorbed by the resistor; in the high-frequency 2.3-8.8GHz broadband, the absorption rate is more than 80%, which has a good stealth protection effect.

[0049] It can be seen that the present invention has a low insertion loss low-frequency passband at low power and an ultra-wide absorption band at high frequency; at high power, it has a higher and broadband shielding effectiveness at low frequency and still has a wider absorption band at high frequency.

[0050] 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 frequency selective layer, the energy selective layer and the dielectric layer (diode and resistor), or changing the structural form, size, and 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 a tortuous structure, comprising a plurality of periodically distributed units, characterized in that: Each unit includes a frequency selection layer, a dielectric layer and an energy selection layer connected in sequence from top to bottom; the sizes of the frequency selection layer, the dielectric layer and the energy selection layer are the same as the size of the unit; The frequency selective layer includes a first dielectric substrate; A first metal zigzag structure, a second metal zigzag structure, a third metal zigzag structure, a fourth metal zigzag structure, a first resistor, a second resistor, a third resistor, and a fourth resistor are provided on the upper surface of the first dielectric substrate; the first metal zigzag structure, the second metal zigzag structure, the third metal zigzag structure, and the fourth metal zigzag structure have the same structure, and all include two metal edges and three metal wires, the two metal edges are vertically arranged, and the three metal wires extend perpendicularly to one of the metal edges toward the center of the first dielectric substrate; one metal edge of the first metal zigzag structure is connected to one metal edge of the second metal zigzag structure through a first resistor, another metal edge of the second metal zigzag structure is connected to one metal edge of the third metal zigzag structure through a second resistor, another metal edge of the third metal zigzag structure is connected to one metal edge of the fourth metal zigzag structure through a third resistor, and another metal edge of the fourth metal zigzag structure is connected to another metal edge of the first metal zigzag structure through a fourth resistor; A fifth metal zigzag structure, a sixth metal zigzag structure, a seventh metal zigzag structure, an eighth metal zigzag structure, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor are provided on the lower surface of the first dielectric substrate; the fifth metal zigzag structure, the sixth metal zigzag structure, the seventh metal zigzag structure, and the eighth metal zigzag structure have the same structure and are all in a continuous "bow" shape, one end of the fifth metal zigzag structure is connected to one end of the sixth metal zigzag structure through a fifth resistor, the other end of the sixth metal zigzag structure is connected to one end of the seventh metal zigzag structure through a sixth resistor, the other end of the seventh metal zigzag structure is connected to one end of the eighth metal zigzag structure through a seventh resistor, and the other end of the eighth metal zigzag structure is connected to the other end of the fifth metal zigzag structure through the eighth resistor; The selectable layer includes a second dielectric substrate and a first metal block structure, a second metal block structure, a third metal block structure, a fourth metal block structure, a fifth metal block structure, a sixth metal block structure, a seventh metal block 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 thereof.

2. The low-pass high-absorption energy selective surface based on a tortuous structure according to claim 1, characterized in that: In the energy selectable layer: One end of the first metal block structure is connected to one end of the second metal block structure and one end of the third metal block structure through a first diode and a second diode, respectively, and the other end of the second metal block structure and the other end of the third metal block structure are connected to one end of the seventh metal block structure through a third diode and a fourth diode, respectively; One end of the fourth metal block structure is connected to one end of the fifth metal block structure and one end of the sixth metal block structure through a fifth diode and a sixth diode respectively, and the other end of the second metal block structure and the other end of the third metal block structure are connected to one end of the seventh metal block structure through a third diode and a fourth diode respectively; a rectangular notch is provided at a corner of the seventh metal block structure.

3. A low-pass high-absorption energy selective surface based on a tortuous structure according to claim 1, characterized in that: The first metal zigzag structure, the second metal zigzag structure, the third metal zigzag structure and the fourth metal zigzag structure are arranged with a rotation of 45° about the center of the frequency selection layer, and the first resistor, the second resistor, the third resistor and the fourth resistor are arranged with a rotation of 45° about the center of the frequency selection layer; the fifth metal zigzag structure, the sixth metal zigzag structure, the seventh metal zigzag structure and the eighth metal zigzag structure are arranged with a rotation of 45° about the center of the frequency selection layer, and the fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor are arranged with a rotation of 45° about the center of the frequency selection layer.

4. A low-pass high-absorption energy selective surface based on a tortuous structure according to claim 1, characterized in that: The width of the metal edges and metal lines in the first metal zigzag structure, the second metal zigzag structure, the third metal zigzag structure and the fourth metal zigzag structure is smaller than the width of the metal edges and metal lines in the fifth metal zigzag structure, the sixth metal zigzag structure, the seventh metal zigzag structure and the eighth metal zigzag structure.

5. The low-pass high-absorption energy selective surface based on a tortuous structure according to claim 1, characterized in that: 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.

6. A low-pass high-absorption energy selective surface based on a tortuous structure according to claim 1, characterized in that: The first metal block structure and the fourth metal block structure are symmetrically arranged about the diagonal line of the energy selectable layer, the second metal block structure and the fifth metal block structure are symmetrically arranged about the diagonal line of the energy selectable layer, the third metal block structure and the sixth metal block structure are symmetrically arranged about the diagonal line of the energy selectable layer, and the seventh metal block structure is symmetrically arranged about the diagonal line of the energy selectable layer.

7. A low-pass high-absorption energy selective surface based on a zigzag structure according to claim 1, characterized in that: The medium used in the medium layer is air.

8. The low-pass high-absorption energy selective surface based on a tortuous structure according to claim 1, characterized in that: The first resistor, the second resistor, the third resistor, and the fourth resistor are all resistors with a resistance value of 400Ω, and the fifth resistor, the sixth resistor, the seventh resistor, and the eighth resistor are all resistors with a resistance value of 600Ω.

9. A low-pass high-absorption energy selective surface based on a tortuous structure according to claim 1, characterized in that: The thickness ratio of the first dielectric substrate to the second dielectric substrate is 1:

1.

10. The low-pass high-absorption energy selective surface based on a tortuous structure according to claim 1, characterized in that: The thickness ratio of the second dielectric substrate to the dielectric layer is 1:20.

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