A broadband sidewall patterned absorbing honeycomb structure

Abstract

This invention belongs to the field of electronic materials technology, specifically a broadband sidewall patterned absorbing honeycomb structure. By designing strip-shaped resistive films with equal widths spaced parallel to the Z-direction of the honeycomb aperture and distributed throughout the inner wall of the honeycomb cells, a spiral-like structure of resistive film stripes is formed on the inner wall of the honeycomb cells. This effectively improves the anisotropy of the equivalent dielectric constant of the absorbing honeycomb structure, thus making the structure polarization insensitive. Furthermore, this structural design minimizes the impact of pattern misalignment due to manufacturing precision issues. Moreover, the spiral-like structure creates alternating impedances along the aperture direction, resulting in more reflections and absorptions on the inner wall of the honeycomb cells after the incident wave is incident, due to the angle of the strip-shaped resistive films. This effectively improves impedance matching with air over a broadband range, thereby achieving ultra-wideband absorption performance of 2–18 GHz.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, specifically a broadband sidewall patterned absorbing honeycomb structure. Background Technology

[0002] With the advancement of technology and the widespread use of electronic devices, electromagnetic interference has become an increasingly prominent problem. Absorbing materials can effectively reduce interference between different devices, improving signal clarity and transmission quality. In the field of communications, especially in 5G and the upcoming 6G technologies, absorbing materials play a crucial role in enhancing the stability and reliability of signal transmission. Honeycomb structures, as a classic structure found in nature, have been widely used in the design and fabrication of absorbing materials. The core material of a honeycomb absorbing structure provides excellent mechanical properties, allowing it to be used as a load-bearing component, while the absorbing coating provides good electromagnetic loss performance. Therefore, honeycomb absorbing structures are dual-functional materials that integrate load-bearing and wave absorption. When electromagnetic waves are incident on hexagonal honeycomb cells, the absorbing coating on the cell walls causes multiple reflections of the electromagnetic waves, a process that significantly dissipates electromagnetic wave energy, thus achieving absorption.

[0003] Current traditional microwave absorbing honeycomb manufacturing processes, such as CN105818453A and CN105297530A, involve first manufacturing aramid paper honeycomb and microwave absorbing paste, then attaching the paste to the aramid paper honeycomb through an impregnation process, and finally forming the microwave absorbing honeycomb through curing and other steps. Its advantages are mature technology and simple manufacturing, but its disadvantages are also obvious. Due to the influence of gravity, it is difficult to ensure the uniformity of the microwave absorbing paste on the honeycomb wall during the impregnation process. Furthermore, this manufacturing process results in a simple structure, making it difficult to perform patterned designs on the honeycomb.

[0004] Currently, non-patterned honeycomb structures suffer from limited design flexibility and low freedom in electromagnetic property control. To increase this flexibility, patterned absorbing honeycomb structures are essential. The stretched honeycomb manufacturing process solves this problem. Its process involves screen printing absorbing coating onto blank aramid paper, followed by gluing, paper stacking, stretching, and drying. This results in a product with good uniformity and allows for flexible sidewall pattern design. However, the stretched honeycomb manufacturing process requires precise stacking of the aramid paper. If the upper and lower sheets are not aligned, the designed pattern will misalign after folding into a honeycomb, affecting the electromagnetic absorption effect and causing polarization sensitivity. Summary of the Invention

[0005] To address the aforementioned problems and shortcomings, and to resolve the issues of uneven distribution of absorbing paste on the honeycomb wall and the impact on electromagnetic absorption effect caused by inaccurate paper alignment in the stretching honeycomb manufacturing process, a broadband sidewall patterned absorbing honeycomb structure is proposed. This structure achieves greater than 90% effective absorption of incident electromagnetic waves in a broadband range of 2–18 GHz, is unaffected by process alignment, and its absorption performance can be controlled according to the stretching angle. Furthermore, the structure is insensitive to polarization.

[0006] A broadband sidewall patterned absorbing honeycomb structure includes an absorbing structure and a metal base plate; the absorbing structure is set on the metal base plate and is composed of several hexagonal absorbing honeycomb units, the side length of each hexagon is R, and the height of each honeycomb is h.

[0007] The inner wall of each absorbing cell is loaded with a periodic resistive film; the specific loading method is as follows: the strip resistive film is arranged at a 45° angle with the Z direction of the cell aperture, and the adjacent resistive films are parallel to each other and spaced D apart to fully cover the inner wall of each absorbing cell; 0 < W < R, 0 < D < R.

[0008] The absorbing cell unit achieves polarization insensitivity by stretching one diagonal of its hexagon and changing the two included angles θ corresponding to that diagonal, where θ = 132 to 138°.

[0009] Furthermore, the width of the strip resistive film

[0010] Furthermore, the honeycomb is made of aramid fiber paper, whose real part of relative permittivity ε r The loss angle is 2.3, the loss tangent tanδ is 0.001, R = 2.75 mm, and h = 30 mm.

[0011] Furthermore, θ = 136°.

[0012] Furthermore, the resistive film is made on aramid paper by screen printing, and its sheet resistance is 900-1100Ω / sq.

[0013] In summary, the present invention has the following outstanding advantages:

[0014] 1. The resistive film is printed on aramid paper using screen printing technology, which ensures the uniformity of the resistive film on the honeycomb sidewall.

[0015] 2. By using a spiral-like structure design and controlling the stretching angle θ, the anisotropy of the equivalent dielectric constant of the absorbing cell is effectively improved, thus making the structure insensitive to polarization, and the structure is almost unaffected by pattern misalignment.

[0016] 3. The spiral-like structure design creates directional oblique alternating impedance along the aperture direction (Z direction). As a result, after the incident wave is incident, the angle of the strip resistive film causes it to form more reflections and absorptions on the inner wall of the honeycomb aperture, effectively improving the impedance matching with air in the broadband range, thereby achieving ultra-wideband absorption performance of 2-18 GHz. Attached Figure Description

[0017] Figure 1 This is a top view of the bonding method in the honeycomb processing technology of the embodiment;

[0018] Figure 2 This is a schematic diagram illustrating the control of the honeycomb stretching angle in an embodiment.

[0019] Figure 3 This is a schematic diagram of the structure of Example 1;

[0020] Figure 4 Reflectance curves at different angles were stretched for Example 1;

[0021] Figure 5 The reflectance curve is shown in Example 2. Detailed Implementation

[0022] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0023] A broadband sidewall patterned absorbing honeycomb structure, the specific structure of which is as follows: Figure 3 As shown.

[0024] In this embodiment, the honeycomb fabrication process involves first printing a resistive film onto blank aramid paper using screen printing, followed by steps such as gluing, paper stacking, stretching, and drying. Figure 1 As shown; the arrow points to the adhesive application area. Then, the aramid paper printed with the resistive film is precisely stacked, and the honeycomb shape is controlled by machine stretching. Figure 2 As shown. In actual processing, the stretching angle θ is controlled by measuring the stretching distance l between the upper and lower sheets.

[0025] Example 1

[0026] like Figure 3 As shown, in this embodiment of planar printing design, the resistive films are strip-shaped (rectangular) and parallel to each other, with the spacing between adjacent resistive films... The angle between the length direction of the resistive film and the honeycomb aperture direction (Z direction) is 45°, and the sheet resistance of the resistive film is 1000 Ω / sq. The honeycomb is made of aramid fiber paper, and its relative permittivity real part ε r The loss tangent tanδ is 0.001. The cell height h = 30 mm, and the cell diameter R = 2.75 mm.

[0027] The equivalent electromagnetic parameters of the honeycomb are adjusted by regulating the stretching angle θ, making them tend to be biaxially isotropic. Figure 4 The reflectivity curves are shown for stretching angles θ = 136° and 120°. It can be seen that when the stretching angle θ = 120°, the overlap between the x-polarized and y-polarized reflectivity curves is not ideal, but when the stretching angle is 136°, the x-polarized and y-polarized curves almost overlap. Furthermore, this structure achieves ultra-wideband absorption from 2 to 18 GHz.

[0028] Example 2

[0029] As mentioned earlier, the honeycomb manufacturing process requires precise stacking of aramid paper during actual production. If the upper and lower sheets are not aligned, the designed pattern will be misaligned after folding into a honeycomb. However, the structure of this invention will not be adversely affected by pattern misalignment. In the electromagnetic simulation software CST, this embodiment simulates the situation where the upper and lower sheets are not aligned. Figure 5 The reflectance curves from aligned to misaligned 2R are shown, and it can be seen that paper misalignment does not cause a significant change in the reflectance curves.

[0030] As can be seen from the above embodiments, the present invention, by designing strip resistive films with equal widths spaced parallel to the Z-direction of the honeycomb aperture and fully distributed on the inner wall of the honeycomb cells, ultimately forms a spiral structure of resistive film stripes on the inner wall of the honeycomb cells. This effectively improves the anisotropy of the equivalent dielectric constant of the absorbing honeycomb structure, thus making the structure insensitive to polarization. Furthermore, this structural design has minimal impact from pattern misalignment due to process precision during manufacturing. Moreover, the spiral structure design creates alternating impedances along the aperture direction (Z-direction), resulting in more reflections and absorptions on the inner wall of the honeycomb cells after the incident wave is incident due to the angle of the strip resistive films. This effectively improves impedance matching with air over a wide bandwidth, thereby achieving ultra-wideband absorption performance of 2–18 GHz.

Claims

1. A broadband sidewall patterned absorbing honeycomb structure, characterized in that: It includes an absorbing structure and a metal base plate; the absorbing structure is set on the metal base plate and consists of several hexagonal absorbing honeycomb units, the side length of each hexagon is R, and the height of each honeycomb is h. The inner wall of each absorbing cell is loaded with a periodic resistive film; the specific loading method is as follows: the strip resistive film is placed at a 45° angle with the Z direction of the cell aperture, with adjacent resistive films parallel to each other and spaced D apart to fully cover the inner wall of each absorbing cell. 0 < W < R, 0 < D < R; The absorbing cell unit achieves polarization insensitivity by stretching one diagonal of its hexagon and changing the two included angles θ corresponding to that diagonal, where θ = 132 to 138°. The width of the strip resistive film 2. The broadband sidewall patterned absorbing honeycomb structure as described in claim 1, characterized in that: The honeycomb is made of aramid fiber paper, and its real part of relative permittivity ε r The loss angle is 2.3, the loss tangent tanδ is 0.001, R = 2.75 mm, and h = 30 mm.

3. The broadband sidewall patterned absorbing honeycomb structure as described in claim 1, characterized in that: The value of θ is 136°.

4. The broadband sidewall patterned absorbing honeycomb structure as described in claim 1, characterized in that: The resistive film is made on aramid paper by screen printing, and its sheet resistance is 900-1100Ω / sq.

5. The broadband sidewall patterned absorbing honeycomb structure as described in claim 4, characterized in that: The sheet resistance is 1000Ω / sq.

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