A 2.5D band-stop energy selective surface based on metal vias

Abstract

The present invention discloses a 2.5D band-stop energy selective surface based on metal through-holes, comprising a plurality of periodically distributed units, each of which is mainly composed of a three-layer dielectric substrate, four layers of metal, and three groups of through-holes, wherein the four layers of metal are, from top to bottom, a first frequency-selective layer, a first energy-selective layer, a second energy-selective layer, and a second frequency-selective layer; the three groups of through-holes respectively penetrate the three layers of dielectric substrates to connect adjacent metal layers; a PIN diode is arranged on the metal strip of the energy-selective layer. When low-power is incident, the diode is cut off and the metal through-hole transmission path is cut off. When high-power is incident, the diode is turned on and the metal through-hole transmission causes the current path length to change, and the equivalent inductance changes accordingly, thereby achieving adaptive change of the stop band when incident waves of different powers are incident. The present invention changes the operating frequency band by changing the stop band, making it easier to protect against high-power microwaves and solving the problem of fixed operating frequency band of existing energy selective surfaces.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and further relates to a 2.5D band-stop energy selective surface based on metal vias in the field of electromagnetic field and microwave technology, which can be used as a strong electromagnetic pulse protective shield for normal intensity signal transmission and strong electromagnetic signal shielding. Background Art

[0002] Strong electromagnetic environments pose a variety of threats to electronic communications equipment. The most common strong electromagnetic environment in nature is lightning. Lightning protection devices and lightning rods are common in areas prone to lightning. Furthermore, many systems also take protective measures to protect against the destructive effects of high-altitude electromagnetic pulses (EMPs). High-power electromagnetic environments, as a means of attack, can be intentionally used to damage electronic systems. Lightning electromagnetic pulses (EMPs), naturally occurring high-energy signals, have a frequency band of approximately 0-20 MHz and can generate extremely high field strengths below 1 MHz. High-power electromagnetic pulses (HPEPs), typically generated by high-altitude nuclear explosions, concentrate their energy primarily below 300 MHz. Ultra-wideband electromagnetic pulses (UWBEPs) have an extremely wide frequency band, covering the entire microwave band. High-power microwaves, on the other hand, have a narrower frequency band, with a center frequency between 1 and 300 GHz.

[0003] High-power electromagnetic pulses (HEPs) interfere with and damage electronic systems in three stages: penetration, transmission, and destruction. First, the EEP enters the system through the "front door" and "back door," where it is converted into high currents and voltages that vary in time and space. The energy is then transmitted through the system's internal circuits to vulnerable components, such as electronic components and chips. Finally, this high-energy signal generates significant heat within the components or directly breaks them down, damaging the entire system. High-power electromagnetic protection generally addresses these three key aspects. First, coupling pathways can be blocked by adding protective devices at the "front door" and "back door" to prevent HEPs from entering the system. Second, limiting and filtering the propagation path within the system can be implemented to prevent damage to components. Finally, the electronic equipment's inherent anti-interference capabilities can be enhanced, such as by using high-voltage components. A new approach to EEP protection is to attenuate the various coupling pathways of strong EEPs in space to a level that the system can withstand through reflection, absorption, and isolation.

[0004] Using switching elements to shield electromagnetic waves within the passband has obvious problems: it requires a bias circuit, making this protection mode unsuitable for dealing with sudden high-power electromagnetic pulse interference. Energy-selective surfaces utilize the induced electric field generated by high-power electromagnetic pulses to turn on the diode, allowing the switching characteristics of the PIN diode and the frequency-selective surface to work together to form a metal mesh structure to shield electromagnetic waves. However, most existing energy-selective surfaces have fixed frequency bands that are difficult to change, making them ineffective in dealing with complex environments where operating frequencies are constantly changing. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned existing technologies and fill the gap in the adaptive change of the working frequency band of the energy selective surface, a 2.5D band-stop energy selective surface based on metal vias is proposed. It aims to solve the problem that the frequency band of the existing energy selective surface is fixed and difficult to change, and it cannot cope with the complex environment of constantly changing working frequency. It can meet the function of adaptively changing the protection band as the incident wave power changes.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A 2.5D band-stop energy selective surface based on metal vias, comprising a plurality of periodically distributed units, each unit comprising, from top to bottom, a first frequency selective layer, a first energy selective layer, a second energy selective layer, and a second frequency selective layer;

[0008] The first energy selection layer and the second energy selection layer have the same structure, both including a second metal square ring and four outer metal patches, four inner metal patches, four metal strips and four diodes located in the second metal square ring, wherein one outer metal patch and one inner metal patch are connected by a metal strip, the middle part of each metal strip is interrupted to form a gap, and a diode is provided in the gap to connect the two parts; wherein the positive poles of the diodes are connected to one side of the outer metal patches, and the negative poles of the diodes are connected to one side of the inner metal patches;

[0009] The inner metal patch of the first energy selection layer is connected to the inner metal patch of the second energy selection layer through a second group of metal through holes;

[0010] The outer metal patch of the first energy selection layer is connected to the first frequency selection layer through a first group of metal through holes, and the outer metal patch of the second energy selection layer is connected to the second frequency selection layer through a third group of metal through holes.

[0011] In one embodiment, the four outer metal patches and the four inner metal patches are symmetrical about the center of the second metal square ring.

[0012] In one embodiment, the first frequency selection layer and the second frequency selection layer have the same structure, both including a first metal square ring and four metal circular rings located in the first metal square ring, four square metal patches and four metal patches, the four square metal patches are located at the four top corners of a square, the metal circular ring is connected to the square metal patch with a corner of the square metal patch adjacent to the first metal square ring as the center of the metal circular ring, each metal patch is located between two square metal patches to connect the two square metal patches, and the first group of metal through holes is located at the center of the metal circular ring to connect the first frequency selection layer and the first energy selection layer.

[0013] In one embodiment, the first frequency selective layer metal structure is symmetrical about the horizontal, vertical and diagonal lines, and the first energy selective layer metal structure is symmetrical about the horizontal, vertical and diagonal lines.

[0014] In one embodiment, the metal circular ring and the first metal square ring in the first frequency selection layer are not connected with each other with a gap; the metal patch is in the shape of an "I" and is in a straight line with the center of the square metal patch.

[0015] In one embodiment, the unit period p of the periodically distributed unit is 10 mm; the outer radius r2 of the metal ring is 0.96 mm, and the inner radius r1 is 0.8 mm; the side length l1 of the square metal patch is 2.4 mm; the outer branch length l2 of the metal patch is 1.2 mm, the inner branch length l3 is 0.8 mm, and the branch width w1 is 0.2 mm; the width w2 of the first metal square ring is 0.1 mm; the width w2 of the second metal square ring is 0.1 mm; the outer metal patch is in the shape of a "mountain", the branch width w3 is 0.2 mm, and the branch length l4 is 1.35 mm; the metal strip width w3 is 0.2 mm, and the notch length l5 is 0.4 mm; the spacing g1 of the second group of metal through holes is 1 mm.

[0016] In one embodiment, the outer metal patch and the inner metal patch are both in a "mountain" shape and are connected by a metal strip on the side away from each branch.

[0017] In one embodiment, the first group of metal through holes is located at the end of the middle branch of the outer metal patch to connect the first frequency selection layer and the first energy selection layer; the second group of metal through holes is located at the end of the middle branch of the inner metal patch to connect the first energy selection layer and the second energy selection layer.

[0018] In one embodiment, in the first selective layer, the width of the end branches of the outer metal patch and the inner metal patch is smaller than the diameter of the metal through-holes of the second group of metal through-holes; the outer metal patch and the inner metal patch are the same size and are oriented at a 90° angle; the width of the branches of the outer metal patch and the inner metal patch is equal to the width of the metal strip.

[0019] In one embodiment, the equivalent circuit structures corresponding to the diode in the cut-off and on states are different. Under low-power incidence, the diode in the cut-off state is equivalent to a 0.13pF capacitor, and under high-power incidence, the diode in the on state is equivalent to a 2.1Ω resistor.

[0020] The specific working principle of the present invention is:

[0021] In the present invention, diodes are placed in the gaps between the metal strips of the first and second energy-selective layers. The current path lengths of the diodes differ between the on and off states, resulting in different equivalent inductances in the corresponding equivalent circuits, which in turn varies the frequency response and the stopband. The coupling between the first and second frequency-selective layers, and between the first and second energy-selective layers, influences the frequency response and creates a wide stopband. When a low-power electromagnetic wave signal is transmitted through the surface, the induced electric field is weak, and the coupling voltage across the diode is lower than its conduction threshold, causing the diode to be in the off state. In this case, the current path is short, and the stopband (guard band) falls in the higher-frequency Band 2, while the transmission band (operating band) falls in the lower-frequency Band 1. When a high-power electromagnetic wave signal is transmitted through the surface, the induced electric field is strong, and the coupling voltage across the diode is higher than its conduction threshold, causing the diode to be in the on state. In this case, the current path is long, and the stopband (guard band) shifts to the lower-frequency Band 1, while the transmission band (operating band) falls in the higher-frequency Band 2. This achieves protection against high-power microwaves and electronic communications equipment.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention adaptively controls the on-off state of the diode under the incidence of electromagnetic wave signals of different powers, so that the length of the current transmission path changes, and the equivalent circuit changes accordingly, thereby changing its frequency response result. Specifically, when a low-power electromagnetic wave signal is incident, the diode is cut off, and the first group of metal through-holes used to connect the first frequency-selective layer and the first energy-selective layer cannot transmit current. When a high-power electromagnetic wave signal is incident, the diode is turned on, and the first group of metal through-holes can transmit current. Therefore, the current transmission path length of the diode in the on state is longer than that in the off state, and the equivalent inductance is larger, so the stop band moves to a low frequency, and the operating frequency band changes accordingly. The present invention realizes the protection of the energy selective surface against high-power microwaves through the change of the stop band, which is different from the mainstream design of low insertion loss when low-power electromagnetic waves are incident in a fixed frequency band and high shielding effectiveness when high-power electromagnetic waves are incident. It provides a new idea and method for the energy selective surface to protect against high-power microwaves. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of an embodiment of the present invention;

[0025] Figure 21 is a schematic diagram of an energy selective layer structure according to an embodiment of the present invention;

[0026] Figure 3 is a schematic diagram of the frequency selection layer structure according to an embodiment of the present invention;

[0027] Figure 4 is a schematic diagram of an equivalent circuit according to an embodiment of the present invention;

[0028] Figure 5 FIG. 1 is a diagram of a frequency response characteristic curve of an embodiment of the present invention in two states: a diode cutoff state and a diode conduction state. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0030] The present invention provides a 2.5D band-stop energy selective surface based on metal vias, comprising a plurality of periodically distributed units, each of which is mainly composed of a three-layer dielectric substrate, four layers of metal and three groups of through holes. Figure 1 As shown, the four metal layers, from top to bottom, are the first frequency-selective layer 1, the first energy-selective layer 3, the second energy-selective layer 5, and the second frequency-selective layer 7. These layers are printed on the upper surface of the first dielectric substrate 8, the lower surface of the first dielectric substrate 8 or the upper surface of the second dielectric substrate 9, the lower surface of the second dielectric substrate 9 or the upper surface of the third dielectric substrate 10, and the lower surface of the third dielectric substrate 10, respectively. The three groups of metal vias, from top to bottom, are the first group of metal vias 2, the second group of metal vias 4, and the third group of metal vias 6. The first group of metal vias 2 penetrates the first dielectric substrate 8 to connect the first frequency-selective layer 1 and the first energy-selective layer 3. The second group of metal vias 4 penetrates the second dielectric substrate 9 to connect the first energy-selective layer 3 and the second energy-selective layer 5. The third group of metal vias 6 penetrates the third dielectric substrate 10 to connect the second energy-selective layer 5 and the second frequency-selective layer 7. In the present invention, the first frequency-selective layer 1 and the second frequency-selective layer 7 have the same structure; the first energy-selective layer 3 and the second energy-selective layer 5 have the same structure.

[0031] like Figure 2As shown, taking the first energy selection layer 3 as an example, it includes a second metal square ring 21, four outer metal patches 27, four inner metal patches 24, four metal strips 26 and four diodes 23. The second metal square ring 21 is located at the outermost side of the unit. Each metal patch, metal strip and diode is located in the second metal square ring 21 and is symmetrically distributed with respect to the center of the second metal square ring 21. For ease of description, in the present invention, the length direction of the second metal square ring 21 is defined as the horizontal and vertical directions. An outer metal patch 27 and an inner metal patch 24 are connected by a metal strip 26. The middle part of each metal strip 26 is interrupted to form a gap, and a diode 23 is placed in the gap to connect the two interrupted parts. In the present invention, the outer metal patch 27 refers to the distance between it and the center of the second metal square ring 21, which is greater than the distance between the inner metal patch 24 and the center of the second metal square ring 21. In the present invention, the anode of each diode 23 is connected to one side of the corresponding outer metal patch 27 , and the cathode of each diode 23 is connected to one side of the corresponding inner metal patch 24 .

[0032] The inner metal patch 24 of the first energy selection layer 3 is connected to the inner metal patch 24 of the second energy selection layer 5 through the second group of metal through-holes 4; the outer metal patch 27 of the first energy selection layer 3 is connected to the first frequency selection layer 1 through the first group of metal through-holes 2; the outer metal patch 27 of the second energy selection layer 5 is connected to the second frequency selection layer 7 through the third group of metal through-holes 6.

[0033] The present invention employs a PIN diode mounted on the metal strips of the energy-selective layer. When low-power microwaves are incident on the energy-selective layer, the PIN diode is in the off state. In this state, the high impedance of the diode blocks the transmission path between the metal vias, preventing current from forming an effective conduction path through the metal strips and the vias. Because the current path is blocked, the energy-selective layer has a low equivalent inductance in this state, resulting in a higher resonant frequency. In this state, the frequency response stopband of the present invention lies in a higher frequency range, allowing low-power microwave signals to pass. When high-power microwaves are incident on the energy-selective layer, the strong electric field of the microwaves causes the PIN diode to transition from the off state to the on state. At this point, the diode's impedance is significantly reduced, the transmission path between the metal vias is opened, and current can form an effective conduction path through the metal strips and the vias. Due to the open current path, the equivalent inductance of the energy-selective layer increases in this state, causing its resonant frequency to decrease. At this point, the stopband of the energy-selective surface shifts toward lower frequencies, reflecting or absorbing high-power microwaves, thereby providing effective protection against high-power microwaves. The stopband shift described in the present invention is achieved by switching the PIN diode between the on and off states. The diode's on and off states directly affect the current path length between the metal vias, thereby changing the energy-selective layer's equivalent inductance. This change in equivalent inductance further influences the resonant frequency, enabling the stopband to adaptively adjust according to the power of the incident microwaves. This adaptive change enables the energy-selective surface to automatically adjust its operating frequency band to different incident microwave powers, thereby achieving transmission of low-power microwaves and protection against high-power microwaves.

[0034] In a further embodiment of the present invention, both the outer metal patch 27 and the inner metal patch 24 are shaped like a "mountain," consisting of three parallel branches perpendicularly connected to a base strip, and connected by a metal strip 26 on the side of the base strip away from the branches. This structure creates new inductance and capacitance interlacing between the three parallel branches and the gaps between them, optimizing passband flatness. Furthermore, the strip connecting the inner and outer metal patches significantly increases the effective inductance of the energy-selective layer, further miniaturizing the overall structure.

[0035] Preferably, the parallel branches in the single outer metal patch 27 and the inner metal patch 24 of the present invention are of the same length. The first group of metal vias 2, located at the middle branch ends of the three parallel branches of the outer metal patch 27, connect the first frequency-selective layer 1 and the first energy-selective layer 3; the second group of metal vias 4, located at the middle branch ends of the three parallel branches of the inner metal patch 24, connect the first energy-selective layer 3 and the second energy-selective layer 5. Connecting the upper and lower layers through metal vias adds a new transmission path, realizing the 2.5D structural design of the present invention. While significantly increasing the equivalent inductance of the overall structure and thus improving the degree of miniaturization, it also provides new ideas for energy-selective surface design.

[0036] Preferably, the outer metal patch 27 and the inner metal patch 24 are the same size, ensuring the same equivalent inductance. The three parallel branches of the outer metal patch 27 are oriented perpendicularly to the three parallel branches of the inner metal patch 24, forming a 90° angle between them. This ensures polarization stability. Furthermore, preferably, the three parallel branches of the outer metal patch 27 are oriented horizontally, while the three parallel branches of the inner metal patch 24 are oriented vertically.

[0037] In a further embodiment of the present invention, the width of the branch at the end of the outer metal patch 27 and the inner metal patch 24 is smaller than the diameter of the metal vias of the second group of metal vias 4, ensuring that interlayer transmission does not leak and increasing structural stability. Preferably, the width of the branch at the end of the outer metal patch 27 and the inner metal patch 24 is equal to the width of the metal strip 26.

[0038] In a further embodiment of the present invention, Figure 3 As shown, taking the first frequency-selective layer 1 as an example, it includes four metal rings 11, four square metal patches 13, four metal patches 14, and a first metal square ring 15. The first metal square ring 15 is located at the outermost side of the unit, and each metal ring and metal patch is located within the first metal square ring 15. The four square metal patches 13 are located at the four vertex positions of a square. The square and the first metal square ring 15 preferably have a common center, and each side is parallel or perpendicular to each side of the first metal square ring 15. In the present invention, the sides of the first metal square ring 15 are preferably horizontal or vertical. In the present invention, the metal structure of the first frequency-selective layer 1 is preferably symmetrical about the horizontal, vertical, and diagonal lines. Correspondingly, the metal structure of the first energy-selective layer 3 is also preferably symmetrical about the horizontal, vertical, and diagonal lines. The metal ring 11 is connected to the square metal patch 13 with a corner of the square metal patch 13 adjacent to the first metal square ring 15 (i.e., the corner closest to a vertex of the first metal square ring 15) as the center of the metal ring 12, and each metal patch 14 is located between two square metal patches 13 to connect the two square metal patches 13; the first group of metal through holes 2 is located at the center of the metal ring 12 to connect the first frequency selection layer 1 and the first energy selection layer 3.

[0039] In a further embodiment of the present invention, the metal circular ring 11 and the first metal square ring 15 in the first frequency-selective layer 1 are not connected with each other with a gap, thereby ensuring that there is a wide gap between them, which will not affect the frequency response; the metal patch 14 is in the shape of an "I", and the structure is composed of three parallel branches vertically connected to the basic strip. The three parallel branches and the gaps between the branches respectively form new inductors and capacitors, which optimizes the passband flatness and is preferably in a straight line with the center of the square metal patch 13.

[0040] Figure 4The principle of the present invention is shown. In the figure, Z0 is the wave impedance in free space, with a magnitude of 377 Ω, and Z1 is the impedance corresponding to the dielectric substrate. Combining Figure 1 , Figure 2 , Figure 3 Analyzing the equivalent schematic diagram, on the first frequency selection layer 1, C1 corresponds to the gap between the first metal square ring 15 and the metal circular ring 11, C2 is in parallel with L1 corresponding to the metal circular ring 11, and C3 is in parallel with L2 corresponding to the square metal patch 13 and the metal patch 14; on the first energy selection layer, C4 corresponds to the gap between the second metal square ring 21 and the outer metal patch 27, L3 corresponds to the outer metal patch 27, and L4 is in parallel with the PIN corresponding to the metal strip 26 for connection and the diode 23 placed at the notch therein. When the diode 23 is cutoff, it is equivalent to a capacitor, and when the diode 23 is conducting, it is equivalent to a resistor. The two states of the diode 23 affect the change of the equivalent inductance. C5 is in parallel with L5 corresponding to the inner metal patch 24. The first frequency selection layer 1 is the same as the second frequency selection layer 7, and the first energy selection layer 3 is the same as the second energy selection layer 5.

[0041] The following further illustrates the technical effects of the present invention in combination with simulation experiments:

[0042] The diode 23 is a BAR6402V model diode produced by Infineon Technologies AG. The equivalent circuit structures corresponding to the cutoff and conducting states are different. Under low-power incidence, the diode 23 is in the cutoff state and is equivalent to a 0.13 pF capacitor, and under high-power incidence, the diode 23 is in the conducting state and is equivalent to a 2.1 Ω resistor. The first dielectric substrate 8, the second dielectric substrate 9, and the third dielectric substrate 10 use F4B as the dielectric, with a dielectric constant of 2.65 and a thickness of 3 mm. The first group of metal vias 2, the second group of metal vias 4, and the third group of metal vias 6 have the same size, with a length equal to the thickness of the dielectric substrate, which is 3 mm, and a radius of 0.15 mm. The unit period p = 10 mm; the outer radius r2 of the metal circular ring 11 is 0.96 mm, and the inner radius rl is 0.8 mm; the side length l1 of the square metal patch 13 is 2.4 mm; the outer branch length l2 of the metal patch 14 is 1.2 mm, the inner branch length l3 is 0.8 mm, and the branch width wl is 0.2 mm; the width w2 of the first metal square ring 15 is 0.1 mm; the width w2 of the second metal square ring 21 is 0.1 mm; the outer metal patch 27 is in the shape of a "mountain", with a branch width w3 of 0.2 mm and a branch length l4 of 1.35 mm; the width w3 of the metal strip 26 is 0.2 mm, and the notch length l5 is 0.4 mm; the pitch gl of the second group of metal vias 4 is 1 mm.

[0043] The S-parameter curve obtained by modeling and simulating the embodiment of the present invention using the commercial simulation software CST Studio Suite 2020 is as Figure 5 shown. Figure 5The horizontal axis is the frequency value in GHz, and the vertical axis is the S parameter in dB. Figure 5 As shown, the current path lengths of the diode in the on and off states vary, corresponding to different equivalent inductances in the equivalent circuit. This results in a change in the frequency response and the stopband. When a low-power electromagnetic wave signal is transmitted through the surface, the induced electric field is weak, and the coupling voltage across the diode is lower than its conduction threshold, placing the diode in the off state. At this point, the current path is short, and the stopband (protection band) falls within the higher-frequency band (6.78-7.77 GHz), while the transmission band (operating band) falls within the lower-frequency band (5.62-6.32 GHz). When a high-power electromagnetic wave signal is transmitted through the surface, the induced electric field is strong, and the coupling voltage across the diode is higher than its conduction threshold, placing the diode in the on state. At this point, the current path is long, and the stopband (protection band) shifts to the lower-frequency band (5.62-6.32 GHz), while the transmission band (operating band) falls within the higher-frequency band (6.78-7.77 GHz). This achieves protection against high-power microwaves and electronic communications equipment. The frequency band 1 (5.62-6.32 GHz) and the frequency band 2 (6.78-7.77 GHz) are based on a stopband protection standard greater than 10 dB.

[0044] Although the specific embodiments of the present invention are described in detail in conjunction with the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

[0045] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A 2.5D band-stop energy selective surface based on metal vias, comprising a plurality of periodically distributed units, each unit comprising, from top to bottom, a first frequency selective layer (1), a first energy selective layer (3), a second energy selective layer (5) and a second frequency selective layer (7); The first energy selection layer (3) and the second energy selection layer (5) have the same structure, both comprising a second metal square ring (21) and four outer metal patches (27), four inner metal patches (24), four metal strips (26) and four diodes (23) located in the second metal square ring (21), wherein one outer metal patch (27) and one inner metal patch (24) are connected by a metal strip (26), the middle part of each metal strip (26) is interrupted to form a gap, and a diode (23) is provided in the gap to connect the two parts; wherein the positive pole of each diode (23) is connected to one side of the outer metal patch (27), and the negative pole of each diode (23) is connected to one side of the inner metal patch (24); The inner metal patch (24) of the first energy selection layer (3) is connected to the inner metal patch (24) of the second energy selection layer (5) via a second group of metal through holes (4); The outer metal patch (27) of the first energy selection layer (3) is connected to the first frequency selection layer (1) through a first group of metal through holes (2), and the outer metal patch (27) of the second energy selection layer (5) is connected to the second frequency selection layer (7) through a third group of metal through holes (6); The first frequency selection layer (1) and the second frequency selection layer (7) have the same structure, both comprising a first metal square ring (15) and four metal circular rings (11) located in the first metal square ring (15), four square metal patches (13) and four metal patches (14), the four square metal patches (13) being located at the four vertices of a square, the metal circular ring (11) being connected to the square metal patch (13) with a corner of the square metal patch (13) adjacent to the first metal square ring (15) as the metal circular ring center (12), each metal patch (14) being located between two square metal patches (13) to connect the two square metal patches (13), the first group of metal through holes (2) being located at the metal circular ring center (12) to connect the first frequency selection layer (1) and the first energy selection layer (3).

2. The 2.5D band-stop energy selective surface based on metal vias according to claim 1, characterized in that: The four outer metal patches (27) and the four inner metal patches (24) are respectively symmetrical about the center of the second metal square ring (21).

3. The 2.5D band-stop energy selective surface based on metal vias according to claim 1, characterized in that: The metal structure of the first frequency selection layer (1) is symmetrical about the horizontal, vertical and diagonal lines, and the metal structure of the first energy selection layer (3) is symmetrical about the horizontal, vertical and diagonal lines.

4. The 2.5D band-stop energy selective surface based on metal vias according to claim 1, characterized in that: The metal circular ring (11) and the first metal square ring (15) in the first frequency selection layer (1) are not connected with each other with a gap; the metal patch (14) is in the shape of an "I" character and is in a straight line with the center of the square metal patch (13).

5. The 2.5D band-stop energy selective surface based on metal vias according to claim 4, characterized in that: The unit period of the periodically distributed unit is p=10mm; the outer radius r2=0.96mm and the inner radius r1=0.8mm of the metal ring (11); the side length l1=2.4mm of the square metal patch (13); the outer branch length l2=1.2mm of the metal patch (14), the inner branch length l3=0.8mm, and the branch width w1=0.2mm; the first metal square ring (15) has a width w2=0.1mm; the second metal square ring (21) has a width w2=0.1mm; the outer metal patch (27) is in the shape of a "mountain", the branch width w3=0.2mm, and the branch length l4=1.35mm; the metal strip (26) has a width w3=0.2mm and a notch length l5=0.4mm; and the spacing g1=1mm of the second group of metal through holes (4).

6. The 2.5D band-stop energy selective surface based on metal vias according to any one of claims 1 to 5, characterized in that: The outer metal patch (27) and the inner metal patch (24) are both in the shape of a mountain, and are connected by a metal strip (26) on the side away from each branch.

7. The 2.5D band-stop energy selective surface based on metal vias according to claim 6, characterized in that: The first group of metal through holes (2) is located at the middle branch end of the outer metal patch (27) and connects the first frequency selection layer (1) and the first energy selection layer (3); the second group of metal through holes (4) is located at the middle branch end of the inner metal patch (24) and connects the first energy selection layer (3) and the second energy selection layer (5).

8. The 2.5D band-stop energy selective surface based on metal vias according to claim 6, characterized in that: In the first selective layer (3), the width of the end branches of the outer metal patch (27) and the inner metal patch (24) is smaller than the diameter of the metal through-holes of the second group of metal through-holes (4); the outer metal patch (27) and the inner metal patch (24) are of the same size and are oriented at an angle of 90°; the width of the branches of the outer metal patch (27) and the inner metal patch (24) is equal to the width of the metal strip (26).

9. The 2.5D band-stop energy selective surface based on metal vias according to claim 1, characterized in that: The diode (23) has different equivalent circuit structures in the cut-off and on states. Under low-power incident conditions, the diode (23) is equivalent to a 0.13pF capacitor in the cut-off state, and is equivalent to a 2.1Ω resistor in the on state under high-power incident conditions.

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