Frequency tunable energy selection unit and surface

Abstract

The application provides a frequency-adjustable energy selection unit and surface, comprising a three-layer metal unit, a diode combination and a dielectric substrate design, realizes a working frequency agility function based on manual control through an applied bias voltage and an energy selection function controlled adaptively through sensing spatial energy, and has multiple functions of working frequency selection, working frequency band agility and spatial energy selection. The application solves the problem of unadjustable working frequency of the energy selection surface, so that the energy selection surface can not only realize strong electromagnetic protection, but also resist electronic interference, greatly expanding the function of the energy selection surface.

Description

Technical Field

[0001] This invention mainly relates to the field of electromagnetic protection technology, and in particular to a frequency-adjustable energy selection unit and surface. Background Technology

[0002] With the rapid development of electronic information technology, the integration, intelligence, and miniaturization of various electronic information devices are constantly improving. Their frequencies are increasing, energy consumption is decreasing, and performance is significantly enhanced. However, this also greatly increases the sensitivity and vulnerability of electronic information devices to electromagnetic interference and attacks. Simultaneously, with the proliferation of electronic devices, the electromagnetic environment is becoming increasingly complex, with mutual interference and influence between different devices. Therefore, there is an urgent need to improve the adaptability of electronic devices in complex electromagnetic environments, namely, their resistance to electromagnetic interference and electromagnetic damage.

[0003] Currently, most protection against strong electromagnetic threats relies on "backdoor" measures such as filtering, shielding, and grounding, and these have been studied relatively extensively. However, research on "frontdoor" protection methods is insufficient. Current methods primarily involve adding high-power limiters to the front-end circuit. While high-power attenuators can significantly reduce the current flowing into the circuit, they also affect the passage of normal signals. Another approach is to add filters or frequency selective surfaces (FSS) at the front end. While these can isolate high-power signals outside the band, they cannot protect against strong electromagnetic threats within the band. Furthermore, although front-end filters or FSSs can isolate high-power signals outside the band, they cannot adaptively change their operating state according to changes in the electromagnetic environment, and therefore cannot effectively protect against strong electromagnetic pulses within the passband.

[0004] Energy Selective Surfaces (ESS) are adaptive electromagnetic protection devices designed to protect against strong electromagnetic pulses. For example, patent document CN101754668A discloses an ESS with low-pass electromagnetic energy characteristics, achieving protection below the L-band. ESS primarily utilizes PIN diodes to replace a portion of the metal grid, forming a periodic structure. By leveraging the significant impedance difference between PIN diodes under zero-bias and forward-biased conditions, the voltage induced across the diodes is controlled by the intensity of the incident electromagnetic field, thus controlling the diode's on / off state. This results in a protective structure that is equivalent to a disconnected metal structure before and after diode conduction, and an equivalent to a complete metal shielding mesh, thereby generating different transmission characteristics for the incident electromagnetic field and achieving adaptive protection. ESS can adaptively shield against strong electromagnetic pulses without affecting the normal operation of electronic equipment, and its development and design are of great significance for strong electromagnetic pulse protection. Subsequently, patent document CN112103660A discloses a C-band broadband ESS, and patent document CN113131221A discloses an X-band ESS. The energy-selective surface technology proposed in existing patent literature addresses the problem of strong electromagnetic field protection within the operating band from a new perspective, effectively protecting against strong electromagnetic signals without affecting the normal operation of the equipment. However, the operating frequency band of the energy-selective protective surface proposed in these patents is fixed and cannot be changed once designed, resulting in low practicality. Furthermore, in complex electromagnetic environments, a fixed operating frequency band is susceptible to interference, making it difficult to solve the problem of anti-interference.

[0005] Comparing operating frequency bands, publicly available literature has not yet reported on energy selective surfaces with adjustable operating frequencies. Since many current communication systems require frequency agility and interference resistance, the development of energy selective surfaces with variable operating frequency bands is of great significance. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention proposes a frequency-tunable energy selection unit and surface. This invention introduces the concept of an adjustable energy selection surface and provides a specific implementation method, overcoming the drawback of the non-tunable operating frequency of energy selection surfaces. This enables the energy selection surface to not only provide strong electromagnetic protection but also resist electronic interference, greatly expanding the functionality of the energy selection surface.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A frequency-tunable energy selection unit includes a top metal unit, a first dielectric substrate, an intermediate metal unit, a second dielectric substrate, and a bottom metal unit stacked sequentially from bottom to top; the adjustable energy selection unit has a metal via through the center of the top metal unit, the first dielectric substrate, the intermediate metal unit, the second dielectric substrate, and the bottom metal unit, and the top metal unit, the intermediate metal unit, and the bottom metal unit are connected to each other through the metal via.

[0009] The top metal unit includes an outer metal frame and a cross-shaped metal plate located at the center of the metal frame. The four sides of the cross-shaped metal plate are respectively opposite to the four sides of the metal frame, and a pair of diodes connected in parallel are loaded in the gaps between them. Each pair of diodes includes a PIN diode and a varactor diode. All diodes in this metal unit have the same positive and negative polarity.

[0010] The intermediate metal unit includes two long metal strips that intersect perpendicularly in a cross shape. The two long metal strips intersect at their respective midpoints, and a metal via is connected to the midpoint of the two long metal strips.

[0011] The structural design of the bottom metal unit is the same as that of the top metal unit.

[0012] The capacitance of each varactor diode in the top metal unit and the bottom metal unit is adjusted by the applied bias voltage, while the switching on and off of the PIN diode is autonomously controlled by spatial electromagnetic waves.

[0013] Furthermore, the first dielectric substrate and the second dielectric substrate of the present invention are made of the same material and have the same thickness.

[0014] Furthermore, in this invention, when an external power supply is applied, the metal frames of the top and bottom metal units are connected to the same terminal of the power supply, while the elongated metal strip of the middle metal unit is connected to the other terminal of the power supply. The positive and negative terminals of the power supply are opposite to the positive and negative terminals of the diodes in the top and bottom metal units. This can be divided into two cases, as detailed below:

[0015] When all diode anodes are connected to the cross-shaped metal plate and all diode cathodes are connected to the metal frame, the metal frames of the top and bottom metal units are connected to the positive terminal of the power supply, and the long metal plate of the middle metal unit is connected to the negative terminal of the power supply.

[0016] When all diode negative terminals are connected to the cross-shaped metal plate and all diode positive terminals are connected to the metal frame, the metal frames of the top and bottom metal units are connected to the negative terminal of the power supply, and the long metal plate of the middle metal unit is connected to the positive terminal of the power supply.

[0017] Furthermore, the four sides of the cross-shaped metal sheet of the present invention are perpendicular to the four sides of the metal frame, and the relative gaps are equal.

[0018] Furthermore, the adjustable energy selection unit of the present invention has a square cross-section, and the metal frame is a square metal frame, the side length of which is equal to the side length of the adjustable energy selection unit.

[0019] Furthermore, the lengths of the two elongated metal strips in this invention are both equal to the side length of the adjustable energy selection unit, and the two elongated metal strips are parallel to the transverse and longitudinal sides of the adjustable energy selection unit, respectively.

[0020] Furthermore, the two long metal strips of this invention have equal widths.

[0021] Furthermore, the present invention realizes the frequency regulation function and energy selection function of the energy selection unit through a combination of semiconductor devices composed of PIN diodes and varactor diodes. The capacitance value of the varactor diode is manually adjusted by the applied DC bias voltage, while the switching on and off of the PIN diode is autonomously controlled by spatial electromagnetic waves.

[0022] Specifically, when the electromagnetic energy in the space is lower than the design threshold, the PIN diode is in a non-conducting state, and the PIN diode is equivalent to a capacitor. The PIN diode, varactor diode, and each metal unit together generate a bandpass electromagnetic response, and the signal in the band can pass through. At this time, the total capacitance of the PIN diode and varactor diode is controlled by the DC bias voltage applied to the varactor diode. The operating frequency band of the energy selection unit is adjusted by changing the magnitude of the DC bias voltage applied to the varactor diode.

[0023] When the electromagnetic energy in the space exceeds the design threshold, the PIN diode is turned on by the radio frequency signal induced on the metal structure, which is equivalent to a resistor. The varactor diode is short-circuited, the passband of the energy selection unit is turned off, and the electromagnetic signal is reflected.

[0024] Based on any of the frequency-tunable energy selection units described above, the present invention provides a frequency-tunable energy selection surface, which includes a series of frequency-tunable energy selection units arranged in a periodic array.

[0025] Compared with the prior art, the technical effects of the present invention are as follows:

[0026] This invention provides a smart electromagnetic material that can improve the resistance of electronic devices to electromagnetic damage and electromagnetic interference, namely a frequency-tunable energy selection unit, and further proposes a frequency-tunable energy selection surface based on the frequency-tunable energy selection unit.

[0027] The energy selection surface includes a series of frequency-adjustable energy selection units arranged in a periodic array. Through the structural design of the energy selection units, specifically including the design of a three-layer metal unit, a diode combination, and a dielectric substrate, the system achieves both a frequency agility function based on manual control via an applied bias voltage and an energy selection function based on adaptive control via sensing spatial energy. It has multiple functions including operating frequency selection, operating frequency band agility, and spatial energy selection.

[0028] In this invention, the combination and placement of diodes are specially designed to achieve both manual and adaptive control. In weak electromagnetic environments, i.e., when the electromagnetic energy in space is low and below the design threshold, the PIN diode does not conduct. The operating frequency band of the energy selection unit can be adjusted by the magnitude of the DC bias voltage applied to the varactor diode. This adjustment process can be manually controlled or automatically designed to suppress electromagnetic interference. When the spatial electromagnetic energy exceeds the design threshold, this invention can adaptively sense the energy intensity and control the conduction state of the PIN diode by sensing the energy of the spatial electromagnetic waves, thus closing the operating passband and shielding the electromagnetic waves. This process is adaptively controlled by the device and can be used for electromagnetic protection, safeguarding electronic equipment, and suppressing electronic interference, greatly expanding the functionality of the energy selection surface. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the top metal unit according to an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of an interlayer metal unit in one embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of the bottom metal unit according to an embodiment of the present invention;

[0034] Figure 5 The equivalent circuit model diagram of an energy selection unit with adjustable frequency when the PIN diode is not conducting under weak electromagnetic energy environment;

[0035] Figure 6The equivalent circuit model diagram of an energy selection unit with adjustable frequency when the PIN diode is turned on under strong electromagnetic energy environment;

[0036] Figure 7 This is a diagram showing the transmission parameters of a frequency-adjustable energy selection unit under different states in one embodiment of the present invention;

[0037] The image is labeled as follows:

[0038] 1. Top-layer metal unit; 11. First metal frame; 12. First cross-shaped metal sheet;

[0039] 2. First dielectric substrate;

[0040] 3. Intermediate layer metal unit; 31. First long strip metal sheet; 32. Second long strip metal sheet;

[0041] 4. Second dielectric substrate;

[0042] 5. Bottom metal unit; 51. First metal frame; 52. First cross-shaped metal piece;

[0043] 6. Metal vias;

[0044] 7. Varactor diode;

[0045] 8. PIN diode. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0047] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0048] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0051] Reference Figure 1 In one embodiment of the present invention, a frequency-adjustable energy selection unit is provided, comprising, from bottom to top, a top metal unit 1, a first dielectric substrate 2, an intermediate metal unit 3, a second dielectric substrate 4, and a bottom metal unit 5. A metal via 6 is provided at the center of the adjustable energy selection unit, penetrating the top metal unit 1, the first dielectric substrate 2, the intermediate metal unit 3, the second dielectric substrate 4, and the bottom metal unit 5. The top metal unit 1, the intermediate metal unit 3, and the bottom metal unit 5 are connected through the metal via 6. In a preferred embodiment of the present invention, the first dielectric substrate 2 and the second dielectric substrate 4 are made of the same material and have the same thickness. During manual power supply, the top metal unit 1 and the bottom metal unit 5 are connected to the same pole of the power supply, and the intermediate metal unit 3 is connected to the other pole of the power supply. The positive and negative poles of the power supply are opposite to the positive and negative poles of the diodes in the top and bottom metal units.

[0052] Reference Figure 2 In one embodiment of the present invention, the adjustable energy selection unit has a square cross-section, and the top metal unit 1 includes a first metal frame 11 on the periphery and a first cross-shaped metal piece 12 located at the center of the first metal frame 11. The first metal frame 11 is a square frame, and the side length of the first metal frame 11 is equal to the side length of the adjustable energy selection unit, both being p. The width of the metal piece used in the first metal frame is s. The first cross-shaped metal piece 12 has a symmetrical structure in all directions, and the width and length of the four sides of the first cross-shaped metal piece 12 are equal, let the length be c. A metal via 6 passes through the center of the first cross-shaped metal piece 12.

[0053] Reference Figure 2The four sides of the first cross-shaped metal piece 12 are respectively opposite to the four sides of the first metal frame 11, and a pair of diodes are loaded in the gaps between the opposite sides. The four sides of the first cross-shaped metal piece 12 are perpendicular to the four sides of the first metal frame 11, and the gaps between the opposite sides are equal, with a gap distance of f. Each pair of diodes includes a varactor diode 7 and a PIN diode 8; all diodes have the same polarity, and the positive terminals of all diodes are connected to the first cross-shaped metal piece 12, and the negative terminals of all diodes are connected to the first metal frame 11, or all the negative terminals of all diodes are connected to the first cross-shaped metal piece 12, and the positive terminals of all diodes are connected to the first metal frame 11.

[0054] Reference Figure 3 In one embodiment of the present invention, the adjustable energy selection unit has a square cross-section. The intermediate metal unit 3 includes two long metal strips that intersect perpendicularly in a cross shape, namely a first long metal strip 31 and a second long metal strip 32. The lengths of the first long metal strip 31 and the second long metal strip 32 are both equal to the side length p of the adjustable energy selection unit. The two long metal strips are parallel to the horizontal and vertical sides of the adjustable energy selection unit, respectively. The first long metal strip 31 and the second long metal strip 32 intersect at their respective midpoints. A metal via 6 passes through the intersection of the first long metal strip 31 and the second long metal strip 32 and connects to the midpoint of the two long metal strips. Preferably, the widths of the metal strips used for the first long metal strip 31 and the second long metal strip 32 are equal, denoted as w.

[0055] The structural design of the bottom metal unit is the same as that of the top metal unit. (Refer to...) Figure 4 In one embodiment of the present invention, the adjustable energy selection unit has a square cross-section. The bottom metal unit 5 includes a second metal frame 51 on the periphery and a second cross-shaped metal piece 52 located at the center of the second metal frame 51. The second metal frame 51 is a square frame, and the side length of the second metal frame 51 is equal to the side length of the adjustable energy selection unit, both being p. The width of the metal piece used in the first metal frame is s. The second cross-shaped metal piece 52 has a symmetrical structure in all directions, and the width and length of the four sides of the second cross-shaped metal piece 52 are equal, let the length be c. A metal via 6 passes through the center of the second cross-shaped metal piece 52.

[0056] Reference Figure 4The four sides of the second cross-shaped metal piece 52 are respectively opposite to the four sides of the second metal frame 51, and a pair of diodes are loaded in the gaps between the opposite sides. The four sides of the second cross-shaped metal piece 52 are perpendicular to the four sides of the second metal frame 51, and the gaps between the opposite sides are equal, with a gap distance of f. Each pair of diodes includes a varactor diode 7 and a PIN diode 8; all diodes have the same positive and negative polarity, and the positive terminals of all diodes are connected to the second cross-shaped metal piece 52, and the negative terminals of all diodes are connected to the second metal frame 51, or all the negative terminals of all diodes are connected to the second cross-shaped metal piece 52, and the positive terminals of all diodes are connected to the second metal frame 51.

[0057] In a preferred embodiment, each layer of metal unit adopts Figure 2 , 3 In the design structure shown in Figure 4, when manually powered, the top metal unit 1 and the bottom metal unit 5 are connected to the same pole of the power supply, while the middle metal unit 3 is connected to the other pole of the power supply. Specifically, there are two cases:

[0058] When the positive terminals of all diodes in the top and bottom metal units are connected to the cross-shaped metal sheet in the metal unit, and the negative terminals of all diodes are connected to the metal frame in the metal unit, the metal frames of the top and bottom metal units are connected to the positive terminal of the power supply, and the long metal sheet of the middle metal unit is connected to the negative terminal of the power supply.

[0059] When the negative terminals of all diodes in the top and bottom metal units are connected to the cross-shaped metal sheet in the metal unit, and the positive terminals of all diodes are connected to the metal frame in the metal unit, the metal frames of the top and bottom metal units are connected to the negative terminal of the power supply, and the long metal sheet of the middle metal unit is connected to the positive terminal of the power supply.

[0060] The capacitance of each varactor diode in the top metal unit 1 and the bottom metal unit 5 is adjusted by an applied DC bias voltage, while the switching on and off of the PIN diode is autonomously controlled by spatial electromagnetic waves. The varactor diode controls the operating frequency of the energy selection unit, while the PIN diode controls the attenuation of the electromagnetic signal by the energy selection unit. The control methods and modulation effects of the two types of diodes are different and independent of each other.

[0061] In a preferred embodiment, each layer of metal unit adopts Figure 2 , 3 The design structure shown in Figure 4, Figure 5 The equivalent circuit model diagram of an energy selection unit with adjustable frequency when the PIN diode is not conducting under weak electromagnetic energy environment; Figure 6This is an equivalent circuit model diagram of an energy selection unit with adjustable frequency when the PIN diode is conducting under strong electromagnetic energy conditions. L1 represents the cross-shaped metal plates in the top and bottom metal units, L2 represents the metal frames in the top and bottom metal units, and Ls represents the two intersecting long strip metal plates in the middle metal unit. This invention achieves frequency regulation and energy selection functions through a semiconductor device combination consisting of a PIN diode 8 and a varactor diode 7. The varactor diode 7 is regulated by a DC bias voltage, while the PIN diode 8 is controlled by a radio frequency signal in space. Specifically, when a reverse bias voltage is applied to both the varactor diode 7 and the PIN diode 8, the capacitance of the varactor diode 7 changes with the magnitude of the bias voltage, while the equivalent capacitance of the PIN diode 8 remains constant. Therefore, the two diodes are equivalent to variable capacitors, and the total capacitance changes with the DC bias voltage.

[0062] When subjected to an RF signal, PIN diode 8 exhibits switching characteristics. In a space with strong electromagnetic energy, when PIN diode 8 is conducting, it is equivalent to a very small resistor (less than 10 ohms), which is short-circuited for the RF signal. At this time, the varactor diode 7 connected in parallel with it is also short-circuited. Therefore, the two diodes are equivalent to an RF switch, and the switching on and off is controlled by the strength of the RF signal.

[0063] The specific work process is as follows:

[0064] When the electromagnetic energy in the space is low, below the design threshold, the PIN diode is in a non-conducting state. The PIN diode and varactor diode together are equivalent to a variable capacitor Cv, which can be controlled by an external DC bias voltage. The circuit as a whole is a second-order bandpass filter. By changing Cv, the position of the passband can be controlled, thereby adjusting the operating frequency of the energy selection surface. That is, the PIN diode, varactor diode, and each metal unit together generate a bandpass electromagnetic response, allowing signals within the band to pass through. At this time, the total capacitance of the PIN diode and varactor diode is controlled by the DC bias voltage applied to the varactor diode. By changing the magnitude of the DC bias voltage applied to the varactor diode, the operating frequency band of the energy selection unit can be adjusted.

[0065] When the electromagnetic energy in the space is large, exceeding the design threshold, the PIN diode is turned on by the RF signal induced on the metal structure, equivalent to a fixed resistor Rv. The varactor diode is short-circuited, and the entire circuit is equivalent to three parallel inductors. The passband of the energy selection unit is turned off, the electromagnetic signal is reflected, the electromagnetic wave cannot propagate, and strong electromagnetic signals are shielded.

[0066] This invention, through the aforementioned scheme, specifically the design of a three-layer metal unit, diode combination, and dielectric substrate, achieves an energy selection surface with adjustable operating frequency by combining PIN diodes and varactor diodes. The operating frequency of the energy selection unit is changed by controlling the application of different DC bias voltages to the varactor diodes, and the attenuation of electromagnetic signals by the energy selection unit is controlled by the PIN diodes. The energy selection unit can adaptively sense spatial electromagnetic energy without requiring manual control to adjust the attenuation of electromagnetic signals. In particular, it exhibits low signal attenuation under low electromagnetic energy and high signal attenuation under high electromagnetic energy.

[0067] The DC bias voltage applied to the varactor diode can be manually adjusted according to the application, thus the present invention achieves a combination of manual control and strong electromagnetic adaptive sensing control.

[0068] The structure of this invention has universal characteristics. Based on the above structural design, those skilled in the art can modify its specific structural parameters (including but not limited to the width and length of the metal sheet / metal strip / metal frame, the material of the metal sheet / metal strip / metal frame, the selection of the two types of diodes, the size and material of the dielectric substrate, etc.), and the operating frequency band can be moved to other frequency bands.

[0069] In a preferred embodiment, each layer of metal unit adopts Figure 2 , 3 As shown in Figure 4, when an external power supply is applied, the metal frames around the top and bottom metal units are connected to the positive terminal of the power supply, and the long strip metal of the middle metal unit is connected to the negative terminal of the power supply.

[0070] This invention has been verified through simulation and experimentation, and a prototype has been developed; the test results are consistent with expectations. In one specific embodiment, a method is adopted... Figure 1 The structure shown employs different metal units in each layer. Figure 2 , 3 The design structure shown in Figure 4 uses NXP's BA-51-02 PIN diode, F4B dielectric substrate with a thickness h of 2.2 mm, and MACOM's MA46H12 varactor diode. Detailed parameter values ​​for other components are given in Table 1.

[0071] Table 1. Frequency-tunable energy-selective surface structure parameters (unit: mm)

[0072]

[0073] The transmission parameters of the frequency-tunable energy selection unit under different states are as follows: Figure 3As shown, in low electromagnetic energy environments, the transmission curve of the frequency-adjustable energy selection unit can be controlled by adjusting the capacitance of the varactor diode. The center frequency can be adjusted from approximately 5.5 GHz to 3.3 GHz, demonstrating a significant control effect. This function can be used to resist electromagnetic interference. Under strong electromagnetic signals, the signal passband is closed, the transmission coefficient is less than 30 dB, and strong electromagnetic waves are reflected. This function can be used to resist strong electromagnetic damage.

[0074] All diode models in this invention can be replaced by other diodes with the same characteristics. The thickness and dielectric constant of the dielectric substrate can be adjusted appropriately. The dimensions of each metal unit layer in this invention can be scaled down for application to other frequency bands. The feeding method in this invention can be varied depending on the arrangement of the diodes. In addition to being used for electromagnetic damage and electromagnetic interference suppression, this invention can also be used to apply electronic interference. The control method of the PIN diode and varactor diode combination proposed in this invention can also be used to design artificial electromagnetic structures with other functions.

[0075] Based on the frequency-tunable energy selection unit provided in any of the above embodiments, one embodiment of the present invention provides a frequency-tunable energy selection surface, which includes a series of frequency-tunable energy selection units arranged in a periodic array.

[0076] When the electromagnetic energy in space is below the design threshold, this invention has a spatial filtering function, allowing electromagnetic waves within the operating frequency band to pass through. By applying a bias voltage, the inter-junction capacitance of the varactor diode can be controlled, thereby regulating the operating frequency of this invention. This regulation process is manually controlled and can be used to resist electromagnetic interference. When the spatial electromagnetic energy exceeds the design threshold, this invention can adaptively sense the energy intensity and control the conduction state of the PIN diode by sensing the energy of the spatial electromagnetic waves, so that the operating passband is closed and the electromagnetic waves are shielded. This process is adaptively controlled by the device and is used to resist electromagnetic damage.

[0077] This invention possesses dual characteristics of frequency and energy regulation. In the frequency domain, it functions as a spatial filter, acting as a bandpass filter, with its operating frequency band adjustable via an applied bias voltage. In the energy domain, it functions as an energy low-pass selector. This invention can change its operating state in two ways. First, under manual control, the operating frequency can be adjusted within a certain range using a DC bias voltage. Second, it senses the electromagnetic energy in space and attenuates the electromagnetic signal to varying degrees: when the electromagnetic field energy is less than a set energy threshold, the attenuation is minimal, and the signal is received by the system via the operating frequency band; when the electromagnetic field energy exceeds the set threshold, the attenuation is significant, and the signal cannot be received. This invention is applied to the "front door" protection of electronic systems, adaptively protecting them from strong electromagnetic pulse threats. It can also be used for communication anti-interference, significantly improving the survivability and anti-interference capabilities of electronic equipment in complex environments.

[0078] Compared with other existing patents, this invention is the first to realize the energy selection protection feature with adjustable operating frequency. The adjustable effect is obvious, and the protection capability is superior to that in existing literature, which is innovative.

[0079] Matters not covered in this invention are common knowledge.

[0080] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A frequency-tunable energy selection unit, characterized in that, It includes a top metal unit, a first dielectric substrate, a middle metal unit, a second dielectric substrate, and a bottom metal unit stacked from top to bottom; the adjustable energy selection unit has a metal via hole in the center that passes through the top metal unit, the first dielectric substrate, the middle metal unit, the second dielectric substrate, and the bottom metal unit, and the top metal unit, the middle metal unit, and the bottom metal unit are connected to each other through the metal via hole. The top metal unit includes an outer metal frame and a cross-shaped metal plate located at the center of the metal frame. The four sides of the cross-shaped metal plate are respectively opposite to the four sides of the metal frame, and a pair of diodes connected in parallel are loaded in the gaps between them. Each pair of diodes includes a PIN diode and a varactor diode. All diodes in this metal unit have the same positive and negative polarity. The intermediate metal unit includes two long metal strips that intersect perpendicularly in a cross shape. The two long metal strips intersect at their respective midpoints, and a metal via is connected to the midpoint of the two long metal strips. The structural design of the bottom metal unit is the same as that of the top metal unit. The capacitance of each varactor diode in the top metal unit and the bottom metal unit is adjusted by the applied bias voltage, while the switching on and off of the PIN diode is autonomously controlled by spatial electromagnetic waves. All diode anodes are connected to cross-shaped metal plates, all diode cathodes are connected to metal frames, the metal frames of the top and bottom metal units are connected to the positive terminal of the power supply, and the long metal strips of the middle metal units are connected to the negative terminal of the power supply. Alternatively, all diode negative terminals are connected to the cross-shaped metal plate, all diode positive terminals are connected to the metal frame, the metal frames of the top and bottom metal units are connected to the negative terminal of the power supply, and the long metal plate of the middle metal unit is connected to the positive terminal of the power supply. The frequency regulation and energy selection functions of the energy selection unit are realized by combining semiconductor devices composed of PIN diodes and varactor diodes. The capacitance of the varactor diode is manually adjusted by the applied DC bias voltage, while the switching on and off of the PIN diode is autonomously controlled by spatial electromagnetic waves. When the electromagnetic energy in the space is lower than the design threshold, the PIN diode is in a non-conducting state, and the PIN diode is equivalent to a capacitor. The PIN diode, varactor diode and each metal unit together generate a bandpass electromagnetic response, and the signal in the band can pass through. At this time, the total capacitance of the PIN diode and varactor diode is controlled by the DC bias voltage applied to the varactor diode. The operating frequency band of the energy selection unit is adjusted by changing the magnitude of the DC bias voltage applied to the varactor diode. When the electromagnetic energy in the space exceeds the design threshold, the PIN diode is turned on by the radio frequency signal induced on the metal structure, which is equivalent to a resistor. The varactor diode is short-circuited, the passband of the energy selection unit is turned off, and the electromagnetic signal is reflected.

2. The frequency-adjustable energy selection unit according to claim 1, characterized in that, The first dielectric substrate and the second dielectric substrate are made of the same material and have the same thickness.

3. The frequency-tunable energy selection unit according to claim 1 or 2, characterized in that, When an external power supply is applied, the metal frames of the top and bottom metal units are connected to the same pole of the power supply, and the long metal strip of the middle metal unit is connected to the other pole of the power supply. The positive and negative poles of the power supply are opposite to the positive and negative poles of the diodes in the top and bottom metal units.

4. The frequency-adjustable energy selection unit according to claim 3, characterized in that, The four sides of the cross-shaped metal sheet are perpendicular to the four sides of the metal frame, and the gaps between them are equal.

5. The frequency-tunable energy selection unit according to claim 4, characterized in that, The adjustable energy selection unit has a square cross-section, and the metal frame is a square metal frame with a side length equal to the side length of the adjustable energy selection unit.

6. The frequency-tunable energy selection unit according to claim 4, characterized in that, The length of the elongated metal strip is equal to the side length of the adjustable energy selection unit, and the two elongated metal strips are parallel to the horizontal and vertical sides of the adjustable energy selection unit, respectively.

7. A frequency-tunable energy selective surface, characterized in that, It includes a series of frequency-tunable energy selection units arranged in a periodic array as described in any one of claims 1-6.

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