WO2023160435A1

WO2023160435A1 - Optically transparent diffuse reflection wave absorber capable of absorbing and scattering ultra-wideband microwaves

Info

Publication number: WO2023160435A1
Application number: PCT/CN2023/075952
Authority: WO
Inventors: 朱嘉琦; 宋梓诚; 杨磊; 闵萍萍; 张锐聪; 张智博
Original assignee: 哈尔滨工业大学
Priority date: 2022-02-25
Filing date: 2023-02-14
Publication date: 2023-08-31
Also published as: CN114447623A; CN114447623B

Abstract

The present invention relates to an optically transparent diffuse reflection wave absorber, and provides an optically transparent diffuse reflection wave absorber capable of absorbing and scattering ultra-wideband microwaves. The present invention aims to solve the problems of a narrow absorption band and low absorption frequency band coincidence of existing diffuse reflection wave absorber composition units. The optically transparent diffuse reflection wave absorber is sequentially composed of, from top to bottom, an upper-layer patterned conductive film layer, a first transparent substrate, a first dielectric layer, an intermediate-layer patterned conductive film layer, a second transparent substrate, a second dielectric layer, a bottom low-impedance conductive film layer, and a third transparent substrate; the upper-layer patterned conductive film layer is composed of N×M impedance film units; and the N×M impedance film units are composed of first absorption units and second absorption units. The present invention is used for the optically transparent diffuse reflection wave absorber capable of absorbing and scattering ultra-wideband microwaves.

Description

An Optically Transparent Diffuse Reflection Absorber with Ultra-Broadband Microwave Absorption and Scattering

technical field

The invention relates to an optically transparent diffuse reflection absorber.

Background technique

With the escalation of radar electronic warfare, the low detectability of key targets or vehicles has been focused on research. With the rise of the metasurface concept, artificial resonant units are introduced into the design and manufacture of scattered field reduction structures, and effectively improve the stealth performance of facilities and equipment. According to the principle of achieving low detectability, metasurfaces can be divided into metasurface absorbers and metasurface scatterers.

Metasurface absorbers achieve low microwave scattering by dissipating incident waves and generating resistive heat. Metasurface absorbers are often composed of resonators, dielectric substrates, and reflective floors. With the high degree of freedom of the structure, the properties of the metasurface absorber, such as absorption bandwidth, total thickness, flexibility, etc., can be customized.

Through destructive interference, the metasurface scatterer makes the incident electromagnetic wave be evenly scattered to the second half of the space, realizing low microwave detectability. Similar to the structure of the metasurface absorber, the metasurface scatterer introduces anti-phase reflection units and arranges them to achieve a low scattering effect similar to that of the metasurface absorber.

Since the structure of the absorber is similar to that of the scatterer, a structure can be carefully designed to have both microwave absorption and microwave scattering properties, which is called a diffuse reflection absorber. In order to achieve better scattering reduction, the following conditions should be met at the same time: 1. The two units need to meet broadband absorption and the frequency bands of the two are consistent; 2. The reflection phase difference of the two units in the broadband range should be kept within the range of 135° to 225° (called anti-phase frequency band); 3. The absorption frequency band of the two units and the reflection phase difference anti-phase frequency band need to be consistent.

However, the existing diffuse reflection absorbers have certain defects in performance due to not fully satisfying the above conditions, such as:

1. The absorption frequency bands of the two units are narrow-band absorption or multi-frequency narrow-band, and the absorption frequency bands are inconsistent or have a low degree of overlap, and the anti-phase frequency bands meet the broadband requirements. This will result in an anti-reflection effect similar to that of a conventional metasurface absorber or metasurface scatterer, about 10dB reduction.

2. The absorption frequency bands of the two units are narrow-band absorption, and the absorption frequency bands are consistent, and the anti-phase frequency bands meet the broadband requirements. This will cause the diffuse reflection absorber to achieve an excellent anti-reflection effect in the local narrow-band frequency band. The local narrow-band reduction is about 20dB, and the other working frequency bands are about 10dB reduction. The bandwidth is too narrow to lose practicality.

Based on the analysis of the existing diffuse reflection absorber, it is not difficult to find that the condition of the broadband reflection phase difference of the two units is easy to meet. But on this basis, it is very difficult to satisfy the conditions that the two types of units realize broadband absorption and that the absorption frequency bands of the two types of units are consistent. This makes it difficult for diffuse reflectors to achieve strong scattering field reduction over broadband. Design two structural units such that The difficulty of combining broadband absorption and anti-phase absorption characteristics hinders the simultaneous action of the two mechanisms and limits the further development of low-scattering equipment.

Contents of the invention

The present invention solves the problems of narrow absorption bandwidth and low overlapping of absorption frequency bands in existing diffuse reflection absorbers, and provides an optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering.

An optically transparent diffuse reflective absorber with ultra-broadband microwave absorption and scattering, which consists of an upper patterned conductive film layer, a first transparent substrate, a first dielectric layer, a middle patterned conductive film layer, and The second transparent substrate, the second dielectric layer, the bottom low-impedance conductive film layer and the third transparent substrate;

The upper patterned conductive film layer is composed of N×M impedance film units; the N≥5 columns, the M≥5 rows; the N×M impedance film units are composed of the first absorption unit and the second absorption unit, and the quantity and position of the first absorption unit and the second absorption unit on the first transparent substrate are determined by an optimal coding sequence;

The side length P of the first absorption unit and the second absorption unit is both 8 mm to 25 mm, and the center of the first absorption unit and the second absorption unit is provided with a swastika-shaped transparent conductive film, and no transparent conductive film is provided at other positions. The swastika is formed by connecting four L-shaped structures in a circular array, and the end of the L-shaped structure in the center of the array is connected to the side of the adjacent L-shaped structure; the arm used for connection of the L-shaped structure is the inner arm, and the The arm perpendicular to the arm is the outer arm;

Let the length of the inner arm of the L-shaped structure of the first absorption unit be l ₁ , the length of the outer arm of the L-shaped structure be l ₂ , the width of the inner arm of the L-shaped structure be w ₁ , and the width of the outer arm of the L-shaped structure be w ₂ ; l ₁ =0.2 P～0.3P, l ₂ =0.2P～0.5P, w ₁ =0.05P～0.2P, w ₂ =0.05P～0.2P;

Suppose the length of the inner arm of the L-shaped structure of the second absorption unit is L ₁ , the length of the outer arm of the L-shaped structure is L ₂ , the width of the inner arm of the L-shaped structure is W ₁ , and the width of the outer arm of the L-shaped structure is W ₂ ; L ₁ =0.3P ~0.5P, _L2 =0.2P~0.5P, _W1 =0.05P~0.2P, _W2 =0.2P~0.4P;

The middle layer patterned conductive film layer is provided with a middle layer patterned conductive film unit having the same structure as the impedance film unit and corresponding to the position, and no transparent conductive film is set in the area where the swastika is located on the middle layer patterned conductive film unit, and the middle layer patterned The other positions of the conductive film unit are provided with transparent conductive films.

The beneficial effects of the present invention are:

The present invention uses both the absorption principle of the microwave section and the diffuse reflection absorber of the scattering principle. Using a double-layer complementary resonator unit structure, its broadband absorption performance is less affected by the change of resonator parameters. The unit adopting this design can stably realize broadband microwave absorption performance. Further, by appropriately changing the geometric parameters of the resonator, a unit with an antiphase reflection phase in a wide frequency band can be obtained, so that the phase difference of the unit in a wide frequency band satisfies the range of 135° to 225°. The anti-phase frequency band of the proposed broadband unit is consistent with the absorption frequency band, resulting in significantly stronger scattering field reduction in the arranged structure Effect. The proposed structure reduces the scattered field by more than 20dB in the 8.5GHz-21GHz frequency band. At the same time, good scattering field reduction can still be ensured within an inclination angle of 40°.

The invention is used for an optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering.

Description of drawings

Fig. 1 is a schematic structural diagram of a first absorbing unit contained in an optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering of the present invention, 1 is the upper patterned conductive film layer, 2 is the first transparent substrate, and 3 is The middle patterned conductive film layer, 4 is the second transparent substrate, 5 is the bottom low-impedance conductive film layer, 6 is the third transparent substrate, 7 is the first dielectric layer, and 8 is the second dielectric layer;

Fig. 2 is a schematic structural diagram of a second absorbing unit contained in the optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering of the present invention, 1 is the upper patterned conductive film layer, 2 is the first transparent substrate, and 3 is The middle patterned conductive film layer, 4 is the second transparent substrate, 5 is the bottom low-impedance conductive film layer, 6 is the third transparent substrate, 7 is the first dielectric layer, and 8 is the second dielectric layer;

Fig. 3 is the top view of Fig. 1;

Fig. 4 is the top view of Fig. 2;

5 is a side view of FIG. 1, 1 is the upper patterned conductive film layer, 2 is the first transparent substrate, 3 is the middle layer patterned conductive film layer, 4 is the second transparent substrate, 5 is the bottom low-impedance conductive film layer, 6 is the third transparent substrate, 7 is the first dielectric layer, and 8 is the second dielectric layer;

FIG. 6 is a process diagram of determining an optimal coding sequence in Embodiment 1;

7 is a schematic diagram of the number and position of the first absorption unit and the second absorption unit on the first transparent substrate after the optimal coding sequence is determined in the first embodiment;

Fig. 8 is a schematic diagram of the diffuse reflection absorber after the optimal coding sequence is determined in Embodiment 1;

Fig. 9 is a curve diagram of the absorptivity of the first absorbing unit or the second absorbing unit in an optically transparent diffuse reflective absorber with both ultra-broadband microwave absorption and scattering in Embodiment 1 of period boundary calculation; 1 is the first absorbing unit, 2 is the second absorption unit;

Fig. 10 is a reflection phase curve diagram of the first absorbing unit or the second absorbing unit in an optically transparent diffuse reflective absorber with both ultra-broadband microwave absorption and scattering in Embodiment 1 of periodic boundary calculation; 1 is the first absorbing unit, 2 is the second absorption unit, 3 is the phase difference;

Fig. 11 is a reduced scattering field diagram of an optically transparent diffuse reflection absorber with both ultra-broadband microwave absorption and scattering in Embodiment 1, 1 is field superposition calculation, and 2 is full-wave simulation;

Fig. 12 shows the transformation of the optically transparent diffuse reflective absorber with polarization angle in Embodiment 1 with both ultra-broadband microwave absorption and scattering Scattered field reduction map of ;

Fig. 13 is an optically transparent diffuse reflection absorber with both ultra-broadband microwave absorption and scattering in embodiment 1. The scattering field reduction diagram with the increase of TE wave incident angle;

Fig. 14 is a diagram showing the reduction of the scattering field with the increase of the incident angle of TM waves of the optically transparent diffuse reflection absorber with both ultra-broadband microwave absorption and scattering in Embodiment 1.

Detailed ways

Specific implementation mode 1: In conjunction with Figures 1 to 5, this embodiment is an optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering. It consists of an upper patterned conductive film layer, a second A transparent substrate, a first dielectric layer, a middle patterned conductive film layer, a second transparent substrate, a second dielectric layer, a bottom low-impedance conductive film layer and a third transparent substrate;

In this specific embodiment, the patterned conductive film layer in the middle layer and the resistive film unit have a double-layer complementary structure, and the unit shapes and internal swastikas are exactly the same, and only the location of the conductive film is different.

The two structural units (the first absorbing unit and the second absorbing unit) adopted in this specific embodiment have the same anti-phase frequency band and the absorbing frequency band, both of which have wide-band stable absorption performance, and the phase difference in the wide-band satisfies 135° to the 225° interval, and the absorption frequency band is consistent with the anti-phase frequency band.

In this specific embodiment, absorbing units with different reflection phases are arranged in a specific manner on a two-dimensional plane.

In this specific embodiment, the upper patterned conductive film layer and the middle patterned conductive film layer are obtained by laser etching the resistive film or screen printing the resistive film.

The beneficial effects of this embodiment are:

In this embodiment, a diffuse reflection absorber using both the absorption principle in the microwave section and the scattering principle is used. Using a double-layer complementary resonator unit structure, its broadband absorption performance is less affected by the change of resonator parameters. The unit adopting this design can stably realize broadband microwave absorption performance. Further, by appropriately changing the geometric parameters of the resonator, a unit with an antiphase reflection phase in a wide frequency band can be obtained, so that the phase difference of the unit in a wide frequency band satisfies the range of 135° to 225°. The anti-phase frequency band of the proposed broadband unit is consistent with the absorption frequency band, so that the arranged structure has a significantly stronger scattering field reduction effect. The proposed structure reduces the scattered field by more than 20dB in the 8.5GHz-21GHz frequency band. At the same time, good scattering field reduction can still be ensured within an inclination angle of 40°.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that the first dielectric layer and the second dielectric layer are air dielectric layers or plastic foam, and the relative permittivity is 1-1.2. Others are the same as in the first embodiment.

Embodiment 3: This embodiment differs from Embodiment 1 or Embodiment 2 in that: the thickness of the first dielectric layer and the second dielectric layer is 2 mm to 5 mm. Others are the same as in the first or second embodiment.

Embodiment 4: This embodiment differs from Embodiments 1 to 3 in that: the materials of the first transparent base, the second transparent base and the third transparent base are all PET, PEN or PVC. Others are the same as those in Embodiments 1 to 3.

Embodiment 5: This embodiment differs from Embodiments 1 to 4 in that: the thickness of the first transparent base, the second transparent base and the third transparent base is 0.1mm-0.2mm. Others are the same as the specific embodiments 1 to 4.

Embodiment 6: This embodiment differs from Embodiments 1 to 5 in that: the relative dielectric constants of the first transparent substrate, the second transparent substrate and the third transparent substrate are all 2-4. Others are the same as one of the specific embodiments 1 to 5.

Embodiment 7: This embodiment differs from Embodiments 1 to 6 in that the upper patterned conductive film layer, the middle layer patterned conductive film layer and the bottom low-impedance conductive film layer are all ITO films, silver nano Wire film and copper grid film. Others are the same as those in Embodiments 1 to 6.

Embodiment 8: The difference between this embodiment and one of Embodiments 1 to 7 is: the above The surface resistance of the layer patterned conductive film layer is consistent with that of the middle layer patterned conductive film, and the surface resistance is 100Ω/□～150Ω/□; the surface resistance of the bottom low impedance conductive film layer is less than 15Ω/□. Others are the same as those in Embodiments 1 to 7.

Embodiment 9: This embodiment differs from Embodiments 1 to 8 in that: the thickness of the upper patterned conductive film layer, the middle layer patterned conductive film layer and the bottom low-impedance conductive film layer is 0.01 μm to 100 μm . Others are the same as those in Embodiments 1 to 8.

Embodiment 10: This embodiment differs from Embodiments 1 to 9 in that: the first absorbing unit and the second absorbing unit have a phase difference of 135°-225° within 8.4GHz-20GHz. Others are the same as the specific embodiments 1 to 9.

Adopt the following examples to verify the beneficial effects of the present invention:

Embodiment one:

The upper patterned conductive film layer is composed of N×M resistive film units; the N=21 columns, the M=21 rows; the N×M resistive film units are composed of the first absorption unit and the second absorption unit, and the quantity and position of the first absorption unit and the second absorption unit on the first transparent substrate are determined by an optimal coding sequence;

The side length P of the first absorption unit and the second absorption unit is both 15mm, and the center of the first absorption unit and the second absorption unit is provided with a swastika-shaped transparent conductive film, and no transparent conductive film is provided at other positions. It is formed by connecting four L-shaped structures in a circular array, and the end of the L-shaped structure in the center of the array is connected to the side of the adjacent L-shaped structure; the arm used for connection of the L-shaped structure is an inner arm, which is perpendicular to the inner arm the arm of which is the outer arm;

Let the length of the inner arm of the L-shaped structure of the first absorption unit be l ₁ , the length of the outer arm of the L-shaped structure be l ₂ , the width of the inner arm of the L-shaped structure be w ₁ , and the width of the outer arm of the L-shaped structure be w ₂ ; l ₁ =4mm , l ₂ =4mm, w ₁ =1.5mm, w ₂ =1mm;

Let the length of the inner arm of the L-shaped structure of the second absorption unit be _L1 , the length of the outer arm of the L-shaped structure be _L2 , the width of the inner arm of the L-shaped structure be _W1 , and the width of the outer arm of the L-shaped structure _W2 ; _L1 =6mm, L ₂ =5 mm, W ₁ =1.5 mm, W ₂ =4 mm;

The first medium layer and the second medium layer are air medium layers.

The thickness of the first dielectric layer and the second dielectric layer is 4mm.

The materials of the first transparent base, the second transparent base and the third transparent base are all transparent PET.

The thickness of the first transparent base, the second transparent base and the third transparent base is 0.188mm.

The relative dielectric constants of the first transparent base, the second transparent base and the third transparent base are all 2.65.

The upper patterned conductive film layer, the middle layer patterned conductive film layer and the bottom low impedance conductive film layer are all ITO films.

The surface resistance of the upper patterned conductive film layer is the same as that of the middle layer patterned conductive film, and the surface resistance is 110Ω/□; the surface resistance of the bottom low-impedance conductive film layer is 10Ω/□.

The thickness of the upper patterned conductive film layer, the middle layer patterned conductive film layer and the bottom low impedance conductive film layer is 0.01mm.

Figure 6 is a diagram of the determination process of the optimal coding sequence in Embodiment 1; the quantity and position of the first absorption unit and the second absorption unit on the first transparent substrate are determined by the optimal coding sequence in this embodiment, for 21×21 units The matrix arrangement is optimized. In order to avoid the coupling effect between units, the 21×21 units are divided into 7×7 areas, and each area only contains the first absorption unit or the second absorption unit. The 3×3 units contained in an area are called subunits, and then the 7×7 subunits are filled with unit types for optimization. The specific steps are as follows:

(1) Use the genetic algorithm or other local search algorithms to calculate the scattering far-field pattern to determine the spatial position and adopt the unit type to obtain the unit spatial arrangement: optimize the far-field scattering uniformity of the structure by using the genetic algorithm, where the diffuse reflection absorption The volume scattering pattern is calculated by the field superposition method:

Where k is the wave number of electromagnetic waves in vacuum, x _m,n and y _m,n are the horizontal and vertical coordinates of the subarray unit in the mth row and nth column respectively, E _ELE is the scattering field of the subunit, E _META is the total scattering field of the diffuse absorber, θ and φ are the elevation angle and azimuth angle of the far-field pattern coordinate system, respectively;

(2) The fitness function used by the machine optimization algorithm is the reduction of the scattered field relative to the equal-sized metal plate: the optimal coding sequence is obtained by using the reduction of the scattered field as the optimization function:
Fitness＝-20×lg(max(E _META )/max(E _PEC )) (2)

Among them, E _META and E _PEC are the total scattering field of the diffuse reflector absorber and the total scattering field of the equal-sized good conductor, respectively, and max(E) is the function of selecting the strongest electric field amplitude in the second half of the space;

(3) Genetic algorithm is used to randomly generate a population of diffuse reflector absorbers, and evaluate them. Based on the evaluation results, use selection, crossover, and mutation operators to generate new populations, and cycle until the evolution algebra reaches the upper limit or the scattering field is reduced to meet the requirements, as shown in the figure 7 and Figure 8.

Fig. 9 is a curve diagram of the absorptivity of the first absorbing unit or the second absorbing unit in an optically transparent diffuse reflective absorber with both ultra-broadband microwave absorption and scattering in Embodiment 1 of period boundary calculation; 1 is the first absorbing unit, 2 for the second absorption Unit; Fig. 10 is a reflection phase curve diagram of the first absorbing unit or the second absorbing unit in the optically transparent diffuse reflection absorber with both ultra-broadband microwave absorption and scattering in Embodiment 1 of periodic boundary calculation; 1 is the first absorbing unit , 2 is the second absorption unit, 3 is the phase difference; it can be seen from the figure that the absorption rate of the first absorption unit is higher than 0.9 in the wide frequency band of 7GHz to 20.3GHz, and the absorption rate of the second absorption unit in the wide frequency band of 6GHz to 21GHz It is higher than 0.9, and the change range of the two units in the frequency band is small, and the absorption frequency bands of the two are almost completely overlapped, which ensures that the units used in the diffuse reflection absorber meet the broadband absorption conditions. At the same time, the two anti-phase units change smoothly in the 8.4GHz-20GHz broadband and have a large reflection phase difference (145°-215°), which makes it easier to control the far-field scattering in the broadband. The most important thing is that the absorption band is consistent with the band with a large phase difference to ensure the simultaneous application of the two principles, which will effectively improve the scattering reduction effect.

Fig. 11 is a reduced scattering field diagram of an optically transparent diffuse reflection absorber with both ultra-broadband microwave absorption and scattering in Embodiment 1, 1 is field superposition calculation, and 2 is full-wave simulation; it can be seen from the figure that the finally obtained unit arrangement It exhibits a broadband strong scattering field reduction effect, and the scattering field reduction compared with a good conductor is higher than 20dB in the 8.5GHz-21GHz frequency band. At the same time, compared with the exact solution of full-wave simulation, the result obtained by field superposition calculation has less deviation from it. At the same time, the calculation time of field superposition is extremely short, which is about one-thousandth of that of the full-wave simulation. The extremely short calculation time is conducive to the reduction and optimization of the broadband scattering field for large populations.

Fig. 12 is the scattering field reduction diagram of the optically transparent diffuse reflective absorber with both ultra-broadband microwave absorption and scattering as the polarization angle changes in embodiment one; Fig. 13 is the optically transparent absorber with ultra-broadband microwave absorption and scattering in embodiment one The scattering field reduction diagram of the diffuse reflection absorber with the increase of the incident angle of the TE wave; Figure 14 is the scattering field of the optically transparent diffuse reflection absorber with the increase of the incident angle of the TM wave in Embodiment 1 with both ultra-broadband microwave absorption and scattering Reduced figure. It can be seen from the figure that as the polarization angle of the incident wave changes, the scattering field reduction hardly changes, showing good polarization stability. In the incident angle range of 20 degrees, the scattered field reduction of the structure in the working frequency band is higher than 20dB. At the same time, when the incident angle gradually increases to 40 degrees, the scattered field reduction can still be maintained above 10dB in the working frequency band, indicating that the scattered field is reduced. Good angular stability. It can be proved that the structure has good polarization stability and angular stability.

Claims

An optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering is characterized in that it consists of an upper patterned conductive film layer, a first transparent substrate, a first dielectric layer, and a middle patterned conductive film layer from top to bottom. A film layer, a second transparent substrate, a second dielectric layer, a bottom low-impedance conductive film layer and a third transparent substrate;

The upper patterned conductive film layer is composed of N×M impedance film units; the N≥5 columns, the M≥5 rows; the N×M impedance film units are composed of the first absorption unit and the second absorption unit, and the quantity and position of the first absorption unit and the second absorption unit on the first transparent substrate are determined by an optimal coding sequence;

The side length P of the first absorption unit and the second absorption unit is both 8 mm to 25 mm, and the center of the first absorption unit and the second absorption unit is provided with a swastika-shaped transparent conductive film, and no transparent conductive film is provided at other positions. The swastika is formed by connecting four L-shaped structures in a circular array, and the end of the L-shaped structure in the center of the array is connected to the side of the adjacent L-shaped structure; the arm used for connection of the L-shaped structure is the inner arm, and the The arm perpendicular to the arm is the outer arm;

Let the length of the inner arm of the L-shaped structure of the first absorption unit be l 1 , the length of the outer arm of the L-shaped structure be l 2 , the width of the inner arm of the L-shaped structure be w 1 , and the width of the outer arm of the L-shaped structure be w 2 ; l 1 =0.2 P～0.3P, l 2 =0.2P～0.5P, w 1 =0.05P～0.2P, w 2 =0.05P～0.2P;

Suppose the length of the inner arm of the L-shaped structure of the second absorption unit is L 1 , the length of the outer arm of the L-shaped structure is L 2 , the width of the inner arm of the L-shaped structure is W 1 , and the width of the outer arm of the L-shaped structure is W 2 ; L 1 =0.3P ~0.5P, L2 =0.2P~0.5P, W1 =0.05P~0.2P, W2 =0.2P~0.4P;

The middle layer patterned conductive film layer is provided with a middle layer patterned conductive film unit having the same structure as the impedance film unit and corresponding to the position, and no transparent conductive film is set in the area where the swastika is located on the middle layer patterned conductive film unit, and the middle layer patterned The other positions of the conductive film unit are provided with transparent conductive films.
An optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering according to claim 1, characterized in that the first dielectric layer and the second dielectric layer are air dielectric layers or plastic foams, relatively The dielectric constants are all 1-1.2.
An optically transparent diffuse reflective absorber with ultra-broadband microwave absorption and scattering according to claim 1, characterized in that the thickness of the first dielectric layer and the second dielectric layer is 2 mm to 5 mm.
An optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering according to claim 1, characterized in that the materials of the first transparent substrate, the second transparent substrate and the third transparent substrate are all PET, PEN or PVC.
An optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering according to claim 1, characterized in that the thickness of the first transparent substrate, the second transparent substrate and the third transparent substrate is 0.1 mm ~ 0.2mm.
An optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering according to claim 1, characterized in that the relative dielectric of the first transparent substrate, the second transparent substrate and the third transparent substrate The constants are 2-4.
An optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering according to claim 1, characterized in that the upper patterned conductive film layer, the middle layer patterned conductive film layer and the bottom low impedance conductive film layer The film layers are all ITO films, silver nanowire films and copper grid films.
According to claim 1, an optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering is characterized in that the surface resistance of the upper patterned conductive film layer is the same as that of the middle layer patterned conductive film layer, and the surface The resistance is 100Ω/□˜150Ω/□; the surface resistance of the bottom low-impedance conductive film layer is less than 15Ω/□.
An optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering according to claim 1, characterized in that the upper patterned conductive film layer, the middle layer patterned conductive film layer and the bottom low impedance conductive film layer The thickness of the film layer is 0.01 μm-100 μm.
An optically transparent diffuse reflection absorber with ultra-broadband microwave absorption and scattering according to claim 1, characterized in that the first absorbing unit and the second absorbing unit have an angle of 135° within 8.4GHz～20GHz ~225° phase difference.