A low-frequency electromagnetic energy selective surface structure

Abstract

This invention discloses a low-frequency electromagnetic energy selective surface structure in the field of electromagnetic protection technology. The structure comprises a double-layer energy selective surface, including a first surface layer and a second surface layer, which are correspondingly arranged. Both the first and second surface layers are composed of a periodic metal structure loaded with PIN diodes. This invention utilizes the impedance change characteristics of PIN diodes under strong and weak fields. Under strong electromagnetic pulses, the diodes automatically conduct to form a low-impedance shielding mesh, achieving protection performance close to that of a metal shield. Under normal communication conditions with weak fields, the diodes are cut off, exhibiting high capacitive reactance. Combined with the structural resonance of the ring-cross unit, efficient wave transmission is achieved in the L / S band.

Description

Technical Field

[0001] This utility model relates to the field of electromagnetic protection technology, and in particular to a low-frequency electromagnetic energy selective surface structure. Background Technology

[0002] In recent years, high-power microwave weapon technology has developed rapidly, and the strong electromagnetic pulse environment it generates can pose a serious threat to weaponry. Therefore, research on strong electromagnetic protection for weaponry is of great significance. Metal shielding is a common means of strong electromagnetic protection, but while shielding against external interference, it also blocks the transmission of working signals. To achieve compatibility between shielding high-energy electromagnetic waves and transmitting low-energy working signals, an energy selection mechanism needs to be introduced. Energy selective surfaces are a novel type of strong electromagnetic protection structure based on this mechanism, possessing electromagnetic environment adaptive characteristics. They can effectively achieve the function of transmitting low-energy signals and isolating strong electromagnetic pulses, solving the problem of electromagnetic protection and transmit / receive compatibility. In related technologies, CN118645814B discloses a high-shielding-effective energy selective surface that can generate a passband in the C-band, ensuring that the protected antenna can normally receive and transmit signals, and has a fast roll-off characteristic, achieving high shielding effectiveness throughout the C-band even with high power density incident light. CN112117546B discloses a C-band ultra-wideband energy selective surface with an absolute operating bandwidth of 4 GHz. For example, CN115566437B discloses an X-band broadband energy selective surface that adaptively changes its operating state according to the spatial field strength, allowing low-power signals to pass through with low loss while blocking the entry of strong electromagnetic energy, effectively reducing the insertion loss of low-power signals and improving protection performance. CN115458948B discloses a high-frequency ultra-wideband energy selective surface that can achieve electromagnetic protection in the C / X / Ku bands.

[0003] However, existing technologies mainly target electromagnetic protection in higher frequency bands such as C, X, or Ku, but the shielding effectiveness in some frequency bands is less than 20dB, resulting in low protection effectiveness. Effective electromagnetic protection cannot be achieved in lower frequency bands such as L and S bands. Therefore, we propose a low-frequency electromagnetic energy selective surface structure. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention provides a low-frequency electromagnetic energy selective surface structure. It uses a central circular cross unit connected to a PIN diode to form a periodic unit. By adjusting the shape, geometry, number of energy selective surface layers, and interlayer distance of the periodic unit, the resonant characteristics of the energy selective surface are optimized, thereby achieving the goal of low-energy high-pass and strong energy protection in the low-frequency L / S band.

[0005] The purpose of this utility model is achieved as follows: a low-frequency electromagnetic energy selective surface structure, comprising a structure body, wherein the structure body adopts a double-layer energy selective surface, the structure body includes a first surface layer and a second surface layer, the first surface layer and the second surface layer are correspondingly arranged, and the structure of the first surface layer and the second surface layer are both composed of a metal periodic structure loaded with PIN diodes.

[0006] Optionally, the first surface layer and the second surface layer are distributed vertically, and the first surface layer and the second surface layer have the same structure and are symmetrical in position.

[0007] Optionally, the spacing between the first surface layer and the second surface layer is 10 mm.

[0008] Optionally, the periodic structure of the first surface layer includes metal units and PIN diodes. The metal units are arranged in a ring, and a metal cross structure is provided on the outer side of the metal units. The periodic structure is composed of metal units and PIN diodes connected alternately.

[0009] Optionally, the number of metal units is multiple, and the connection between adjacent metal units is composed of two PIN diodes, wherein the two PIN diodes are oriented in opposite directions.

[0010] Optionally, the PIN diode has a resistance of R = 2Ω and a junction capacitance of C = 0.05pF.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0012] 1. By utilizing the impedance change characteristics of PIN diodes under strong and weak fields, the diodes automatically conduct under the action of strong electromagnetic pulses to form a low-impedance shielding mesh, with protection performance close to that of a metal shield; while under the weak field conditions of normal communication, the diodes are cut off and exhibit high capacitive reactance. Combined with the structural resonance of the ring-cross unit, efficient wave transmission is achieved in the L / S band.

[0013] 2. By setting up a double-layer symmetrical circular ring cross unit and a reverse parallel PIN diode, the circular ring structure excites magnetic dipole resonance to enhance low-frequency coupling, and the cross metal extends polarization stability; the reverse parallel diode group not only achieves full polarization response, but also forms a steep field strength threshold switching through distributed parameter control, so that the structure of this application has both wide bandwidth, low insertion loss and high protection dynamic filtering characteristics. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0015] Figure 1 This is a diagram of the low-frequency electromagnetic energy selective surface periodic structure provided by this utility model.

[0016] Figure 2 This is a schematic diagram of the insertion loss in the low-pass state provided by this utility model.

[0017] Figure 3 This is a schematic diagram of the shielding effectiveness under strong electromagnetic environment provided by this utility model. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] like Figures 1 to 3 The low-frequency electromagnetic energy selective surface structure shown includes a structure body. The structure body adopts a double-layer energy selective surface. The structure body includes a first surface layer and a second surface layer, which are correspondingly arranged. The structure of the first surface layer and the second surface layer is composed of a metal periodic structure loaded with PIN diodes.

[0020] It should be noted that energy selective surface technology utilizes the significant impedance difference of PIN diodes under zero-bias and forward-biased conditions to achieve energy selection. Under a strong field, the diode induces conduction due to the electromagnetic field, which can be equivalent to an inductor and resistor in series. The energy selective surface then functions like a complete metal shield, enhancing its ability to reflect electromagnetic fields and thus improving protection. Under a weak field, the diode is in the off state, acting as a capacitor and exhibiting transparency to electromagnetic wave transmission. Therefore, it enables low-energy signals to pass through while isolating strong electromagnetic pulses, solving the problem of electromagnetic protection and transceiver compatibility.

[0021] This application uses a central circular cross unit connected to a PIN diode to form a periodic unit. By adjusting the shape, geometry, number of energy selective surface layers and interlayer distance of the periodic unit, as well as adjusting the diode performance, the resonant characteristics of the energy selective surface are optimized and adjusted, thereby achieving low-energy high-pass and strong energy protection in the low-frequency L / S band.

[0022] Specifically, the first surface layer and the second surface layer are distributed vertically, the first surface layer and the second surface layer have the same structure and are symmetrical in position, and the interval between the first surface layer and the second surface layer is 10mm.

[0023] Furthermore, the identical structure with symmetrical upper and lower sections can ensure better impedance matching during electromagnetic wave transmission, reduce interface reflection loss, and the 10mm interlayer distance can form an effective resonant cavity effect in the L / S band, enhancing the field coupling effect in the low-frequency band.

[0024] Furthermore, when the PIN diode is conducting under a strong field, the synergistic effect of the double-layer structure can form a stronger equivalent shielding network, improving the reflection capability of strong electromagnetic pulses; under a weak field, the symmetrical wave transmission path maintains signal transmission efficiency and achieves more stable transmit and receive compatibility.

[0025] Furthermore, the double-layer symmetrical structure generates enhanced electromagnetic resonance in a specific frequency band through precise spacing control. The 10mm spacing creates a coupling space on the order of half a wavelength between the two energy selective surfaces, which optimizes the transmission characteristics in the low-frequency band and ensures the in-phase superposition of the two reflective surfaces during strong field protection. The two surface layers with identical structures can ensure the consistency of electromagnetic parameters and avoid polarization sensitivity or frequency deviation problems caused by asymmetry. The vertical distribution further expands the working bandwidth through spatial filtering, ultimately achieving a dynamic balance between high transmission and strong protection in the low-frequency band.

[0026] Specifically, the periodic structure of the first surface layer includes metal units and PIN diodes. The metal units are arranged in a ring, and a metal cross structure is arranged on the outside of the metal units. The periodic structure is composed of metal units and PIN diodes connected alternately.

[0027] Furthermore, by adopting a periodic unit structure with an integrated metal cross on the outer side of the ring, combined with the alternating connection of PIN diodes, the field control capability of the energy selective surface can be significantly improved.

[0028] First, the ring structure can excite ring current resonance, enhancing the magnetic field coupling effect in the low-frequency band, while the outer cross metal expands the working bandwidth through the cross-polarized electric field distribution. The alternating connection of PIN diodes forms a continuous conduction path under strong fields, achieving efficient electromagnetic shielding; under weak fields, it maintains signal transmission through the discrete capacitance effect.

[0029] Furthermore, this combined structure utilizes the composite resonance characteristics of a ring and a cross to simultaneously optimize wave transmission and protection performance in the L / S band. Specifically, the ring dominates low-frequency magnetic resonance, the cross structure suppresses high-frequency parasitic resonance, and the distributed layout of diodes ensures the uniformity of the field strength threshold response, ultimately achieving wide-bandwidth, low-insertion-loss intelligent electromagnetic control.

[0030] Specifically, there are multiple metal units, and the connection between adjacent metal units consists of two PIN diodes. The two PIN diodes are oriented in opposite directions, and the resistance of the PIN diodes is R=2Ω, and the junction capacitance is C=0.05pF.

[0031] Furthermore, the anti-parallel structure ensures that one diode is always in a low-impedance conducting state regardless of the change in electromagnetic field polarity, guaranteeing a stable omnidirectional conductive network under strong field conditions and enhancing the reliability of electromagnetic pulse protection. R=2Ω achieves rapid conduction loss. Simultaneously, the 0.05pF junction capacitance forms a high-Q LC resonant circuit in weak fields. Combined with the distributed parameters of the metal unit, deep resonance is generated in the transparent state, effectively reducing insertion loss in the low-frequency band (L / S band). This overcomes the polarity sensitivity problem of a single diode while maintaining high-frequency cutoff characteristics through distributed small capacitors, ultimately achieving intelligent electromagnetic control with wide incident angles and full polarization compatibility.

[0032] For example, this utility model provides a low-frequency electromagnetic energy selective surface, employing a dual-layer energy selective surface design. The upper and lower layers have identical structures, are symmetrically positioned, and are spaced 10mm apart. Each energy selective surface layer consists of a periodic metal structure loaded with PIN diodes. The periodic structure is formed by alternating connections of central circular cross-shaped metal units and PIN diodes. The connection points between the central circular cross-shaped metal units are composed of two PIN diodes with opposite directions. The PIN diodes have a resistance of 2Ω and a junction capacitance of 0.05pF. After the upper and lower energy selective surfaces are composited with 10mm thick PMI foam and trimmed to the test size, insertion loss and shielding effectiveness are tested respectively.

[0033] In the figure, the horizontal axis represents frequency and the vertical axis represents insertion loss. It can be seen that the insertion loss of the energy selective surface sample designed based on the embodiment is less than 1 dB in the 1-4 GHz frequency range, which meets the requirement of broadband low insertion loss in the L / S band.

[0034] like Figure 3 As shown in the figure, the protection effect test results obtained by the sample in the waveguide are shown. The horizontal axis is frequency and the vertical axis is protection effectiveness. It can be seen from the figure that the protection effectiveness is greater than 30dB in the frequency range of 1 to 4 GHz, which meets the requirement of broadband high protection effectiveness in the L / S band.

[0035] The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A low-frequency electromagnetic energy selective surface structure, comprising a structure, characterized in that: The structure employs a dual-layer energy selective surface, comprising a first surface layer and a second surface layer, with the first and second surface layers correspondingly arranged. Both the first and second surface layers are composed of a periodic metal structure loaded with PIN diodes.

2. A low frequency electromagnetic energy selective surface structure according to claim 1, characterized in that: The first surface layer and the second surface layer are arranged vertically, and the first surface layer and the second surface layer have the same structure and are symmetrical in position.

3. A low frequency electromagnetic energy selective surface structure according to claim 2, wherein: The spacing between the first surface layer and the second surface layer is 10 mm.

4. A low frequency electromagnetic energy selective surface structure according to claim 1, wherein: The periodic structure of the first surface layer includes metal units and PIN diodes. The metal units are arranged in a ring, and a metal cross structure is provided on the outside of the metal units. The periodic structure is composed of metal units and PIN diodes connected alternately.

5. A low frequency electromagnetic energy selective surface structure according to claim 4, wherein: The number of metal units is multiple, and the connection between adjacent metal units is composed of two PIN diodes, wherein the two PIN diodes are oriented in opposite directions.

6. A low frequency electromagnetic energy selective surface structure according to claim 1, wherein: The PIN diode has a resistance of R = 2Ω and a junction capacitance of C = 0.05pF.

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