2.5 D band-stop energy selective surface based on metal via holes

Abstract

The invention discloses a 2.5 D band-stop energy selection surface based on metal through holes, which comprises a plurality of periodically distributed units, each unit is mainly composed of three layers of dielectric substrates, four layers of metal and three groups of through holes, and the four layers of metal are a first frequency selection layer, a first selectable layer, a second selectable layer and a second frequency selection layer from top to bottom; the three groups of through holes respectively penetrate through the three layers of dielectric substrates and are used for connecting adjacent metal layers; a PIN diode is arranged on an optional layer metal strip, the diode is cut off during low-power incidence, a metal through hole transmission path is cut off, the diode is conducted during high-power incidence, the length of a current path is changed through metal through hole transmission, equivalent inductance changes accordingly, and self-adaptive change of a stop band during incidence of incident waves with different powers is achieved. According to the invention, the working frequency band is changed through the change of the stop band, high-power microwaves are protected more easily, and the problem that the working frequency band of an existing energy selective surface is fixed is solved.

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 for a strong electromagnetic pulse protective cover for normal intensity signal transmission and strong electromagnetic signal shielding. Background Art

[0002] For electronic communication equipment, the threat of strong electromagnetic environment comes from many aspects. The most common strong electromagnetic environment in nature is lightning. In areas with high incidence of lightning, lightning protection devices and lightning rods are common. In addition, many systems will also take some protective measures to avoid the destructive effects of high-altitude electromagnetic pulses. As a means of attack, high-power electromagnetic environment can be used intentionally to destroy electronic systems. Lightning electromagnetic pulses are naturally generated high-energy signals with a frequency band of about 0-20MHz, and can produce extremely high field strengths below 1MHz; high-power electromagnetic pulses are usually generated by high-altitude nuclear explosions, and their energy is mainly concentrated below 300MHz; the frequency band of ultra-wideband electromagnetic pulses is extremely wide and can cover the entire microwave band; while the frequency band of high-power microwaves is narrower, with a center frequency between 1-300GHz.

[0003] The interference and damage of high-power electromagnetic pulses to electronic systems can be divided into three stages, namely penetration, transmission, and destruction. First, the electromagnetic pulse enters the system through the "front door" and "back door" and is converted into high current and high voltage that vary with time and space; then the energy is transmitted to relatively fragile parts, such as electronic components and chips, through the circuit inside the system; finally, this high-energy signal will generate high heat inside the device or directly break down the device, thereby destroying the entire system. High-power electromagnetic protection also generally starts from these three aspects. First, the coupling path can be cut off, and high-power electromagnetic pulses can be blocked from entering the system by adding protective equipment at the "front door" and "back door"; secondly, the propagation path inside the system can be limited, filtered and other measures can be taken to prevent it from damaging components; finally, the anti-interference ability of the electronic equipment itself can be improved, such as using high-voltage resistant components. Among them, for various coupling channels of strong electromagnetic pulses in space, attenuating them to a level that the system can withstand through reflection, absorption, isolation and other methods is a new idea for electromagnetic pulse protection today.

[0004] There is an obvious problem in using the start and disconnection of switching elements to shield electromagnetic waves in the passband, that is, a bias circuit is required to achieve this. This protection mode is not conducive to dealing with the interference of sudden high-power electromagnetic pulses on the system. The energy selective surface uses the induced electric field excited by the high-power electromagnetic pulse on it to turn on the diode, so that the switching characteristics of the PIN diode and the frequency selective surface work together to form a metal grid structure to shield electromagnetic waves. However, most of the existing energy selective surfaces have fixed frequency bands and are difficult to change, so there are few countermeasures in the complex environment where the operating frequency is constantly changing. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art 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, which aims to solve the problem that the frequency band of the existing energy selective surface is fixed and difficult to change, and cannot cope with the complex environment of constantly changing working frequency, and can meet the function of adaptively changing the protection frequency 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 a first frequency selective layer, a first energy selective layer, a second energy selective layer and a second frequency selective layer from top to bottom;

[0008] The first energy-selective layer has the same structure as the second energy-selective layer, and both include 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 arranged 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 selectable layer is connected to the inner metal patch of the second energy selectable 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 vertex positions 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 with 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 in the first frequency selection layer and the first metal square ring 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 units 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 vias are 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 vias are 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 branches at the ends 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 an angle of 90°; 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 diode has different equivalent circuit structures in the off state and the on state. Under low-power incident light, the diode is equivalent to a 0.13pF capacitor in the off state, and under high-power incident light, the diode is equivalent to a 2.1Ω resistor in the on state.

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

[0021] In the present invention, a diode is placed in the gap in the middle of the metal strip of the first energy selection layer and the second energy selection layer. The current path length of the diode is different in different states of conduction and cutoff, and the equivalent inductance of the corresponding equivalent circuit is different, so that the frequency response result changes and the stop band changes. The first frequency selection layer and the second frequency selection layer and the first energy selection layer and the second energy selection layer are coupled with each other, thereby affecting the frequency response and producing a wide stop band. When a low-power electromagnetic wave signal is emitted through the surface, the induced electric field generated is weak, and the coupling voltage at both ends of the diode is lower than its conduction threshold, and the diode is in the cut-off state. At this time, the current path is short, and the stop band, i.e., the protection band, is located in the higher frequency band 2, and the wave-transmitting band, i.e., the working band, is located in the lower frequency band 1; when a high-power electromagnetic wave signal is emitted through the surface, the induced electric field generated is strong, and the coupling voltage at both ends of the diode is higher than its conduction threshold, and the diode is in the conduction state. At this time, the current path is long, and the stop band, i.e., the protection band, changes to the lower frequency band 1, and the wave-transmitting band, i.e., the working band, is located in the higher frequency band 2. In this way, the function of protecting high-power microwaves and protecting electronic communication equipment is achieved.

[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 selection layer and the first energy selection 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 working frequency band changes accordingly. The present invention realizes the protection of the energy selection 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, and provides a new idea and method for the energy selection surface to protect high-power microwaves. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] Figure 2is 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 a frequency selection layer structure according to an embodiment of the present invention;

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

[0028] Figure 5 It is a schematic diagram of a frequency response characteristic curve of an embodiment of the present invention in two states: a diode cut-off 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 discloses 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 are, from top to bottom, the first frequency selection layer 1, the first energy selection layer 3, the second energy selection layer 5 and the second frequency selection layer 7, and 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 through holes are, from top to bottom, the first group of metal through holes 2, the second group of metal through holes 4 and the third group of metal through holes 6. The first group of metal through holes 2 penetrates the first dielectric substrate 8 to connect the first frequency selection layer 1 and the first energy selection layer 3, the second group of metal through holes 4 penetrates the second dielectric substrate 9 to connect the first energy selection layer 3 and the second energy selection layer 5, and the third group of metal through holes 6 penetrates the third dielectric substrate 10 to connect the second energy selection layer 5 and the second frequency selection layer 7. In the present invention, the first frequency selection layer 1 has the same structure as the second frequency selection layer 7; the first energy selection layer 3 has the same structure as the second energy selection layer 5.

[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, and each metal patch, metal strip and diode are located in the second metal square ring 21, and are respectively distributed symmetrically 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 side of the second metal square ring 21 is defined as horizontal and vertical. An outer metal patch 27 and an inner metal patch 24 are connected by a metal strip 26, and 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; and 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 sets a PIN diode on the metal strip of the energy selection layer. When low-power microwaves are incident on the energy selection layer, the PIN diode is in a cut-off state. At this time, the high impedance characteristics of the diode cause the transmission path between the metal through holes to be cut off, and the current cannot form an effective conduction path through the metal strips and the through holes. Since the current path is blocked, the equivalent inductance of the energy selection layer in this state is small, resulting in a higher resonant frequency. At this time, the frequency response stop band of the present invention is located in a higher frequency range, allowing low-power microwave signals to pass through. When high-power microwaves are incident on the energy selection layer, the strong electric field of the microwaves will cause the PIN diode to change from a cut-off state to a conduction state. At this time, the impedance of the diode is significantly reduced, the transmission path between the metal through holes is turned on, and the current can form an effective conduction path through the metal strips and the through holes. Due to the conduction of the current path, the equivalent inductance of the energy selection layer in this state increases, resulting in a decrease in its resonant frequency. At this time, the stop band of the energy selection surface moves toward the low-frequency direction, forming a reflection or absorption of the high-power microwave, thereby achieving effective protection against high-power microwaves. The stop band change described in the present invention is achieved by switching the conduction and cut-off states of the PIN diode. The conduction and cutoff states of the diode directly affect the current path length between the metal vias, thereby changing the equivalent inductance of the energy selective layer. The change in equivalent inductance further affects the resonant frequency, allowing the stop band to be adaptively adjusted according to the power of the incident microwave. This adaptive change enables the energy selective surface to automatically adjust its operating frequency band when microwaves of different powers are incident, thereby achieving transmission of low-power microwaves and protection against high-power microwaves.

[0034] In a further embodiment of the present invention, the outer metal patch 27 and the inner metal patch 24 are both in the shape of a "mountain", that is, they are formed by three parallel branches vertically connected on the base strip, and are connected by a metal strip 26 on the side of the base strip away from each branch. Through this structure, the three parallel branches of the inner and outer metal patches of the "mountain" shape and the gaps between the branches form new inductance and capacitance interlacing, respectively, optimizing the passband flatness; and the structure of the strip connecting the inner and outer metal patches significantly increases the energy-selective layer equivalent inductance, making the overall structure more miniaturized.

[0035] Preferably, in the single outer metal patch 27 and the inner metal patch 24 of the present invention, the lengths of the parallel branches are the same. The first group of metal through holes 2 is located at the middle branch end of the three parallel branches of the outer metal patch 27, connecting 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 three parallel branches of the inner metal patch 24, connecting the first energy selection layer 3 and the second energy selection layer 5. By connecting the upper and lower layers through metal through holes, a new transmission path is added, realizing the 2.5D structural design of the present invention, which significantly increases the equivalent inductance of the overall structure and thus improves the degree of miniaturization, while providing a new idea for the design of energy selection surfaces.

[0036] Preferably, the outer metal patch 27 of the present invention has the same size as the inner metal patch 24, ensuring that their equivalent inductances are the same. In the outer metal patch 27, the direction of its three parallel branches is perpendicular to the direction of the three parallel branches of the inner metal patch 24, that is, the two directions are at an angle of 90°. This ensures polarization stability. It is further preferred that the length direction of the three parallel branches of the outer metal patch 27 is in the horizontal direction, and the length direction of the three parallel branches of the inner metal patch 24 is in the longitudinal direction.

[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 through hole of the second group of metal through holes 4, which ensures that there will be no leakage during transmission between layers and increases the structural stability. Preferably, the width of the branch 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 selection 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, wherein the first metal square ring 15 is located at the outermost side of the unit, and each metal ring and metal patch are located in the first metal square ring 15. The four square metal patches 13 are located at the four vertex positions of a square, and 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. The present invention preferably has each side of the first metal square ring 15 in the horizontal or vertical direction. The present invention preferably has the metal structure of the first frequency selection layer 1 symmetrical about the horizontal, vertical and diagonal lines, and accordingly, it is also preferred that the metal structure of the first energy selection layer 3 is 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 12 of the metal ring, 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 12 of the metal ring 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 selection 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 base 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 selective layer 1, C1 corresponds to the gap between the first metal square ring 15 and the metal ring 11, C2 is in parallel with L1 corresponding to the metal 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 selective 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 used 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, and C5 is in parallel with L5 corresponding to the inner metal patch 24. The first frequency selective layer 1 is the same as the second frequency selective layer 7, and the first energy selective layer 3 is the same as the second energy selective layer 5.

[0041] The technical effects of the present invention will be further described below in combination with simulation experiments:

[0042] The diode 23 is of the BAR6402V model 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 the dielectric F4B, 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 ring 11 is 0.96 mm, and the inner radius r1 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 w1 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 spacing g1 between the second group of metal vias 4 is 1 mm.

[0043] The S-parameter curves obtained by modeling and simulating the embodiment of the present invention using the commercial simulation software CST Studio Suite 2020 are 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 length is different in different states of the diode being turned on and off, and the equivalent inductance of the corresponding equivalent circuit is different, so that the frequency response result changes and the stopband changes. When a low-power electromagnetic wave signal is emitted through the surface, the induced electric field generated is weak, and the coupling voltage at both ends of the diode is lower than its conduction threshold, and the diode is in the cut-off state. At this time, the current path is short, and the stopband, i.e., the protection frequency band, is located in the higher frequency band 2 6.78-7.77GHz, and the wave-transmitting band, i.e., the working frequency band, is located in the lower frequency band 1 5.62-6.32GHz; when a high-power electromagnetic wave signal is emitted through the surface, the induced electric field generated is strong, and the coupling voltage at both ends of the diode is higher than its conduction threshold, and the diode is in the conduction state. At this time, the current path is long, and the stopband, i.e., the protection frequency band, changes to the lower frequency band 1 5.62-6.32GHz, and the wave-transmitting band, i.e., the working frequency band, is located in the higher frequency band 2 6.78-7.77GHz. In this way, the function of protecting high-power microwaves and protecting electronic communication equipment is achieved. The frequency band 1 5.62-6.32 GHz and the frequency band 2 6.78-7.77 GHz are based on a stop band protection greater than 10 dB.

[0044] Although the specific implementation of the present invention is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in 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 protection scope 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-selective layer (3) and the second energy-selective 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 arranged in the gap to connect the two parts; wherein the positive electrode of the diode (23) is connected to one side of the outer metal patch (27), and the negative electrode of the diode (23) is connected to one side of the inner metal patch (24); The inner metal patch (24) of the first energy selectable layer (3) is connected to the inner metal patch (24) of the second energy selectable 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).

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 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).

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

5. The 2.5D band-stop energy selective surface based on metal vias according to claim 3, 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).

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

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

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

9. The 2.5D band-stop energy selective surface based on metal vias according to claim 7, characterized in that: In the first energy selection layer (3), the widths of the end branches of the outer metal patch (27) and the inner metal patch (24) are 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 at a 90° angle; the branch widths of the outer metal patch (27) and the inner metal patch (24) are equal to the width of the metal strip (26).

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

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