Ultra-wideband passive electromagnetic shielding surface based on Kramers-Kronig relation

Abstract

The invention relates to an ultra-wide-band passive electromagnetic shielding surface based on a Kramers-Kronig relationship, which comprises a plurality of ultra-wide-band passive electromagnetic shielding units, the ultra-wide-band passive electromagnetic shielding units are arranged according to an incident angle of radiated electromagnetic waves to form the ultra-wide-band passive electromagnetic shielding surface, the distances between the ultra-wide-band passive electromagnetic shielding units are the same, and the ultra-wide-band passive electromagnetic shielding units are arranged in a staggered manner. The discrete source is located at a central position of the ultra-wideband passive electromagnetic shielding surface. According to the ultra-wideband passive electromagnetic shielding unit, in the process that the incident angle of electromagnetic waves is increased to 65 degrees, the electromagnetic wave reflection coefficients of the units working at different incident angles are all below-10 dB, and the electromagnetic wave absorption performance is all above 90%; all structural parameters are simple and adjustable, electromagnetic shielding surfaces working at other frequencies can be obtained by adjusting the parameters through the same design method, and effective work in other frequency ranges is achieved; the materials used in the method are common materials, large-scale expansion is easy, and the method has the advantages of being passive, easy to process and low in cost.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic shielding surfaces, in particular to an ultra-wideband passive electromagnetic shielding surface based on Kramers-Kronig relationship. Background Art

[0002] With the rapid development of electronic information technology, various electronic and electrical equipment are increasingly widely used, which brings convenience to people's production and life, but also brings serious problems such as electromagnetic radiation and electromagnetic interference. As an effective solution for electromagnetic shielding, electromagnetic shielding surfaces have been widely developed because they can effectively absorb electromagnetic waves entering the shielding material.

[0003] In order to achieve broadband absorption effect, traditional electromagnetic shielding surfaces usually need to have a large thickness. For example, the pyramidal absorbing materials commonly used in electromagnetic shielding rooms generally have a thickness of more than 30 mm in order to achieve the far-field shielding effect of electromagnetic waves, and when the incident angle of electromagnetic waves increases, its working effect is significantly deteriorated. In recent years, the rapid development of electromagnetic metamaterial technology has provided a feasible idea for the realization of ultra-wideband passive electromagnetic shielding surfaces. The metamaterial structural unit is composed of a periodic arrangement of sub-wavelength-scale artificial resonance units. The change of its equivalent dielectric constant and magnetic permeability can be achieved by artificially controlling the unit structure parameters, which provides a feasible idea for obtaining the desired dispersion response. However, the electromagnetic properties of metamaterials originate from the strong dispersion of the absorption resonance zone, and the dispersion is inevitably accompanied by large losses and a narrow working frequency band. In order to broaden the electromagnetic wave absorption band, multi-layer metamaterials and multi-size metal pattern nested metamaterials have been widely studied. However, the thickness of the multi-layer metamaterial absorber is large; the absorption peaks of the multi-size metal pattern nested metamaterial are severely coupled, and only a limited expansion of the working frequency band can be achieved on a limited size. Summary of the invention

[0004] In order to solve the problem of large loss and narrow operating frequency of traditional metamaterial structural units, the purpose of the present invention is to provide a passive, low-cost, wide operating frequency range, high-performance ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship, comprising a plurality of ultra-wideband passive electromagnetic shielding units, wherein the plurality of ultra-wideband passive electromagnetic shielding units are arranged according to the incident angle of the radiated electromagnetic wave to form an ultra-wideband passive electromagnetic shielding surface, the spacing between the ultra-wideband passive electromagnetic shielding units is the same, and the discrete source is located at the center of the ultra-wideband passive electromagnetic shielding surface.

[0006] The ultra-wideband passive electromagnetic shielding unit comprises a first dielectric substrate, a second dielectric substrate, a third dielectric substrate, a metal pattern and a metal grounding layer. The first dielectric substrate and the second dielectric substrate are placed horizontally, the first dielectric substrate is located above the second dielectric substrate, the third dielectric substrate is sandwiched between the first dielectric substrate and the second dielectric substrate, the board surface of the third dielectric substrate is perpendicular to the board surfaces of the first dielectric substrate and the second dielectric substrate, the first dielectric substrate, the second dielectric substrate and the third dielectric substrate jointly form an I-shape, the metal pattern is printed on a side board surface of the third dielectric substrate, the metal grounding layer forms the back surface, the metal grounding layer is used to connect the first dielectric substrate, the second dielectric substrate and the third dielectric substrate, and the plane where the metal grounding layer is located is perpendicular to the board surfaces of the first dielectric substrate, the second dielectric substrate and the third dielectric substrate.

[0007] When the incident angle of the electromagnetic wave increases to 65°, the electromagnetic wave reflection coefficients of the ultra-wideband passive electromagnetic shielding units working at different incident angles are all below -10dB, the electromagnetic wave absorption performance is all above 90%, and the absorption bandwidth remains approximately stable.

[0008] The ultra-wideband passive electromagnetic shielding surface has an operating frequency range of 8 GHz to 12 GHz, a relative bandwidth of 40%, and achieves near-perfect absorption of electromagnetic waves within a 4 GHz bandwidth.

[0009] The metal pattern is roughly in the shape of a circular ring, with two parallel lines extending inward from an opening on one side of the circular ring, the two parallel lines have the same length, and a resistor R is welded between the two parallel lines; for a given discrete source, an ultra-wideband passive electromagnetic shielding unit operating at different incident angles is obtained by adjusting the resistance value of the resistor R and the structural parameters of the metal pattern, and the structural parameters of the metal pattern include r, m, n and t, wherein r is the inner diameter of the circular ring, m is the spacing between the two parallel lines, the width of the circular ring and the line width of the two parallel lines are both n, and t is the length of the two parallel lines.

[0010] The first dielectric substrate, the second dielectric substrate and the third dielectric substrate are all made of Rogers low-loss plate, the dielectric constants of the first dielectric substrate, the second dielectric substrate and the third dielectric substrate are all 4.64, and the loss tangents of the first dielectric substrate, the second dielectric substrate and the third dielectric substrate are all 0.015; the metal grounding layer is made of a copper plate with a thickness of 0.018 mm.

[0011] It can be seen from the above technical scheme that the beneficial effects of the present invention are as follows: first, in the ultra-wideband passive electromagnetic shielding unit of the present invention, when the electromagnetic wave incident angle increases to 65°, the electromagnetic wave reflection coefficient of the unit working at different incident angles is all below -10dB, and the electromagnetic wave absorption performance is all above 90%; second, for a given discrete source, the present invention arranges the above units according to the incident angle of the discrete source radiation, thereby realizing an ultra-wideband passive electromagnetic shielding surface, the surface has an operating frequency range of 8GHz to 12GHz, a relative bandwidth of 40%, and can achieve near-perfect absorption of electromagnetic waves within a bandwidth range of 4GHz, providing a feasible idea for realizing ideal electromagnetic shielding of discrete sources; third, the unit structure of the present invention is uniform and unified, and each structural parameter is simple and adjustable. The electromagnetic shielding surface working at other frequencies can be obtained by adjusting the parameters by the same design method, so as to realize effective operation in other frequency ranges; fourth, the materials used in the present invention are all common materials, which are easy to expand on a large scale and have the advantages of being passive, easy to process and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the present invention;

[0013] Figure 2 It is a structural schematic diagram of the ultra-wideband passive electromagnetic shielding unit in the present invention;

[0014] Figure 3 It is a schematic diagram of the structure of the metal pattern in the present invention;

[0015] Figure 4 It is the reflection parameter simulation result of the ultra-wideband passive electromagnetic shielding unit of the present invention working at different incident angles;

[0016] Figure 5 This is the electric field distribution diagram of the present invention under the condition of a given discrete source and a frequency of 8 GHz;

[0017] Figure 6 It is the electric field distribution diagram of the present invention under the condition of a given discrete source and a frequency of 10 GHz.

[0018] Figure 7 This is the electric field distribution diagram of the present invention under the condition of a given discrete source and a frequency of 12 GHz. DETAILED DESCRIPTION

[0019] like Figure 1 As shown, an ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship includes a plurality of ultra-wideband passive electromagnetic shielding units 8, wherein the plurality of ultra-wideband passive electromagnetic shielding units 8 are arranged according to the incident angle of the radiated electromagnetic wave to form an ultra-wideband passive electromagnetic shielding surface 1, the spacing between the ultra-wideband passive electromagnetic shielding units 8 is the same, and the discrete source 2 is located at the center of the ultra-wideband passive electromagnetic shielding surface 1.

[0020] like Figure 2 As shown, the ultra-wideband passive electromagnetic shielding unit 8 includes a first dielectric substrate 3, a second dielectric substrate 4, a third dielectric substrate 5, a metal pattern 6 and a metal grounding layer 7. The first dielectric substrate 3 and the second dielectric substrate 4 are placed horizontally, the first dielectric substrate 3 is located above the second dielectric substrate 4, the third dielectric substrate 5 is sandwiched between the first dielectric substrate 3 and the second dielectric substrate 4, the board surface of the third dielectric substrate 5 is perpendicular to the board surfaces of the first dielectric substrate 3 and the second dielectric substrate 4, the first dielectric substrate 3, the second dielectric substrate 4, and the third dielectric substrate 5 together form an I-shape, the metal pattern 6 is printed on one side of the board surface of the third dielectric substrate 5, the metal grounding layer 7 forms the back, the metal grounding layer 7 is used to connect the first dielectric substrate 3, the second dielectric substrate 4 and the third dielectric substrate 5, and the plane where the metal grounding layer 7 is located is perpendicular to the board surfaces of the first dielectric substrate 3, the second dielectric substrate 4 and the third dielectric substrate 5. The first dielectric substrate 3, the second dielectric substrate 4, and the third dielectric substrate 5 are all made of Rogers low-loss plates, and the dielectric constants of the first dielectric substrate 3, the second dielectric substrate 4, and the third dielectric substrate 5 are all 4.64, and the loss tangents of the first dielectric substrate 3, the second dielectric substrate 4, and the third dielectric substrate 5 are all 0.015; the metal grounding layer 7 is made of a copper plate with a thickness of 0.018 mm. Since the constitutive parameters of the ultra-wideband passive electromagnetic shielding unit 8, namely the dielectric constant and the magnetic permeability, satisfy the Krammers-Kronig relationship, it means that there is a mutually restrictive relationship between the real part and the imaginary part of the constitutive parameters. Therefore, if the imaginary part (or real part) of the constitutive parameter is controlled, the real part (or imaginary part) of the constitutive parameter can be correspondingly regulated. Based on the above principle, multiple resonances are introduced, and the lumped parameter element, namely the resistor R, is introduced into the resonant unit metal pattern 6. By changing the resistance value of the resistor R, the purpose of regulating the working bandwidth of the ultra-wideband passive electromagnetic shielding unit 8 is achieved.

[0021] When the incident angle of the electromagnetic wave increases to 65°, the electromagnetic wave reflection coefficient of the ultra-wideband passive electromagnetic shielding unit 8 working at different incident angles is below -10dB, the electromagnetic wave absorption performance is above 90%, and the absorption bandwidth remains approximately stable. The operating frequency range of the ultra-wideband passive electromagnetic shielding surface 1 is 8GHz to 12GHz, the relative bandwidth is 40%, and near-perfect absorption of electromagnetic waves is achieved within a bandwidth range of 4GHz.

[0022] like Figure 3As shown, the metal pattern 6 is roughly in the shape of a ring, and two parallel lines 9 are extended inward from an opening on one side of the ring. The two parallel lines 9 have the same length, and a resistor R is welded between the two parallel lines 9. For a given discrete source 2, by adjusting the resistance value of the resistor R and the structural parameters of the metal pattern 6, an ultra-wideband passive electromagnetic shielding unit 8 working at different incident angles is obtained. The structural parameters of the metal pattern 6 include r, m, n and t, wherein r is the inner diameter of the ring, m is the spacing between the two parallel lines 9, the width of the ring and the line width of the two parallel lines 9 are both n, and t is the length of the two parallel lines 9.

[0023] By adjusting the resistance value of the resistor R and the structure of the metal pattern 6, the dispersion of the equivalent constitutive parameters of the unit at different incident angles is precisely controlled, and the ultra-wideband passive electromagnetic shielding unit 8 working at different incident angles is obtained. The specific parameter data are shown in Table 1. Figure 1 As shown, for a given discrete source, its position is defined as (0, 0), the vertical distance from the electromagnetic wave radiated by the discrete source to the ultra-wideband passive electromagnetic shielding surface 1 is d, the unit at the vertical distance d from the discrete source, i.e. the position (d, 0), is defined as 0° unit U1, the incident angle of 5° for the electromagnetic wave radiated by the discrete source on the shielding surface is unit U2, and U3, U4, U5...U15 are defined by analogy for each increase of 5°. The ultra-wideband passive electromagnetic shielding surface 1 is composed of the above-mentioned ultra-wideband passive electromagnetic shielding units 8 arranged according to the incident angle of the electromagnetic wave radiated by the given discrete source.

[0024] Table 1 Parameters of ultra-wideband passive electromagnetic shielding units working at different incident angles

[0025]

[0026] In order to verify the sensitivity of the ultra-wideband passive electromagnetic shielding surface 1 to the incident angle, the ultra-wideband passive electromagnetic shielding unit 8 is simulated and optimized based on the electromagnetic simulation software CST. Figure 4 It can be seen that when the frequency is between 8 GHz and 12 GHz and the electromagnetic wave incident angle increases from 0° to 65°, the electromagnetic wave reflection coefficient of the ultra-wideband passive electromagnetic shielding surface 1 is below -10dB, and its electromagnetic wave absorption performance is above 90%, that is, the ultra-wideband passive electromagnetic shielding surface 1 can also effectively absorb electromagnetic waves when the electromagnetic waves are obliquely incident.

[0027] For a given discrete source 2, the electric field distribution obtained by simulation at frequencies of 8 GHz, 10 GHz and 12 GHz shown in the ultra-wideband passive electromagnetic shielding surface 1 is as follows: Figure 5 , Figure 6 and Figure 7As shown, it can be seen that the absorption effect is different under different frequencies. Obviously, the absorption effect is the best at 8GHz, but almost no electromagnetic waves penetrate the absorption surface at each frequency, the electric field distribution is relatively flat, and there is no obvious standing wave effect. Therefore, the constructed ultra-wideband passive electromagnetic shielding surface 1 can achieve a good shielding effect for electromagnetic waves radiated by a given discrete source 2 in the near field.

[0028] The ultra-wideband passive electromagnetic shielding unit 8 has a uniform and unified structure, uses common materials, is easy to expand on a large scale, and has the advantages of being passive, easy to process, and low-cost.

[0029] To sum up, in the ultra-wideband passive electromagnetic shielding unit 8 of the present invention, when the electromagnetic wave incident angle increases to 65°, the electromagnetic wave reflection coefficient of the unit working at different incident angles is all below -10dB, and the electromagnetic wave absorption performance is all above 90%; for a given discrete source 2, the present invention arranges the above-mentioned units according to the radiation incident angle of the discrete source 2, thereby realizing an ultra-wideband passive electromagnetic shielding surface, the surface operating frequency range is 8GHz to 12GHz, the relative bandwidth is 40%, and it can achieve near-perfect absorption of electromagnetic waves within the 4GHz bandwidth range, providing a feasible idea for realizing the ideal electromagnetic shielding of discrete sources; the unit structure of the present invention is uniform and unified, and each structural parameter is simple and adjustable. The electromagnetic shielding surface working at other frequencies can be obtained by adjusting the parameters by the same design method, so as to realize effective operation in other frequency ranges; the materials used in the present invention are all common materials, which are easy to expand on a large scale and have the advantages of being passive, easy to process and low cost.

[0030] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship, characterized in that: The invention comprises a plurality of ultra-wideband passive electromagnetic shielding units (8), wherein the plurality of ultra-wideband passive electromagnetic shielding units (8) are arranged according to the incident angle of the radiated electromagnetic wave to form an ultra-wideband passive electromagnetic shielding surface (1), the spacings between the ultra-wideband passive electromagnetic shielding units (8) are the same, and the discrete source (2) is located at the center of the ultra-wideband passive electromagnetic shielding surface (1).

2. The ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship according to claim 1, characterized in that: The ultra-wideband passive electromagnetic shielding unit (8) comprises a first dielectric substrate (3), a second dielectric substrate (4), a third dielectric substrate (5), a metal pattern (6) and a metal grounding layer (7). The first dielectric substrate (3) and the second dielectric substrate (4) are placed horizontally, the first dielectric substrate (3) is located above the second dielectric substrate (4), the third dielectric substrate (5) is sandwiched between the first dielectric substrate (3) and the second dielectric substrate (4), the plate surface of the third dielectric substrate (5) is perpendicular to the plate surfaces of the first dielectric substrate (3) and the second dielectric substrate (4), the first dielectric substrate (3), the second dielectric substrate (4) and the third dielectric substrate (5) together form an I-shaped plate, the metal pattern (6) is printed on one side of the plate surface of the third dielectric substrate (5), the metal grounding layer (7) forms the back surface, the metal grounding layer (7) is used to connect the first dielectric substrate (3), the second dielectric substrate (4) and the third dielectric substrate (5), and the plane where the metal grounding layer (7) is located is perpendicular to the plate surfaces of the first dielectric substrate (3), the second dielectric substrate (4) and the third dielectric substrate (5).

3. The ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship according to claim 1, characterized in that: When the incident angle of the electromagnetic wave increases to 65°, the electromagnetic wave reflection coefficient of the ultra-wideband passive electromagnetic shielding unit (8) working at different incident angles is all below -10dB, the electromagnetic wave absorption performance is all above 90%, and the absorption bandwidth remains approximately stable.

4. The ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship according to claim 1, characterized in that: The ultra-wideband passive electromagnetic shielding surface (1) has an operating frequency range of 8 GHz to 12 GHz, a relative bandwidth of 40%, and achieves near-perfect absorption of electromagnetic waves within a 4 GHz bandwidth range.

5. The ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship according to claim 2, characterized in that: The metal pattern (6) is roughly in the shape of a ring, with an opening on one side of the ring extending inwardly from two parallel lines (9), the two parallel lines (9) having the same length, and a resistor R welded between the two parallel lines (9); for a given discrete source (2), by adjusting the resistance value of the resistor R and the structural parameters of the metal pattern (6), an ultra-wideband passive electromagnetic shielding unit (8) operating at different incident angles is obtained, and the structural parameters of the metal pattern (6) include r, m, n and t, wherein r is the inner diameter of the ring, m is the spacing between the two parallel lines (9), the width of the ring and the line width of the two parallel lines (9) are both n, and t is the length of the two parallel lines (9).

6. The ultra-wideband passive electromagnetic shielding surface based on the Kramers-Kronig relationship according to claim 2, characterized in that: The first dielectric substrate (3), the second dielectric substrate (4), and the third dielectric substrate (5) are all made of Rogers low-loss plate materials; the dielectric constants of the first dielectric substrate (3), the second dielectric substrate (4), and the third dielectric substrate (5) are all 4.64; the loss tangents of the first dielectric substrate (3), the second dielectric substrate (4), and the third dielectric substrate (5) are all 0.015; and the metal grounding layer (7) is made of a copper plate with a thickness of 0.018 mm.

Images