Frequency selection wave absorber with wave trapping characteristic

Abstract

The invention discloses a frequency selection wave absorber with a wave trapping characteristic. The wave absorber is sequentially provided with a loss layer, an air layer and a reflecting layer from top to bottom. The loss layer comprises a first dielectric substrate and an absorption unit arranged on the upper surface of the first dielectric substrate, the absorption unit comprises a first metal patch and a resistor patch, the first metal patch comprises an inner ring rectangular patch, an edge rectangular patch and an E-shaped patch, the edge rectangular patch is connected with the corner of the inner ring rectangular patch through the rectangular patch, and the edge rectangular patch is connected with the E-shaped patch through the resistor patch; and the E-shaped patch is connected with the edge rectangular patch. The reflecting layer comprises a second dielectric substrate and a reflecting unit arranged on the upper surface of the second dielectric substrate, the reflecting unit comprises a second metal patch, and an annular gap is formed in the second metal patch. The invention solves the technical problem that the existing frequency selective surface is difficult to realize the integration of broadband absorption and specific frequency point notch at the same time, and has the advantages of simple structure, insensitive polarization, wide absorption bandwidth, adjustable notch and the like.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave modulation technology, and specifically to a frequency-selective absorber with notch characteristics. Background Technology

[0002] Against the backdrop of rapid development in information technology, electromagnetic waves, as the core carrier of information transmission, have crucial application value in fields such as radar stealth, wireless communication, electromagnetic compatibility, aerospace, and satellite communication due to their precise control technology. Frequency selective surfaces (FSS), as a two-dimensional periodic array structure with spatial filtering characteristics, are composed of metal patches or slotted elements. By changing the element structure, they can selectively transmit or reflect electromagnetic waves in specific frequency bands, thus possessing frequency selection capabilities.

[0003] With the continuous upgrading of modern wireless communication and radar technology, the industry has put forward higher requirements for the control and utilization of electromagnetic wave propagation. Traditional frequency selective surfaces can only achieve a single transmission or reflection function, and cannot simultaneously meet the integrated application requirements of absorbing waves in a specific frequency band and transmitting waves in other frequency bands. They are difficult to adapt to the usage scenarios of radar antenna radomes and other equipment that require both stealth and communication. Therefore, frequency selective surfaces with notching characteristics have become a research hotspot in the field of electromagnetics. Summary of the Invention

[0004] The purpose of this invention is to provide a frequency-selective absorber with notch characteristics to solve the technical problem that existing frequency-selective surfaces cannot simultaneously achieve broadband absorption and specific frequency notch filtering.

[0005] To achieve the above objectives, the technical solution provided by the present invention is: a frequency selective absorber with notch characteristics, wherein a loss layer, an air layer and a reflection layer are arranged sequentially from top to bottom; The loss layer includes a first dielectric substrate and an absorption unit disposed on the upper surface of the first dielectric substrate. The absorption unit includes a first metal patch and a resistor patch, and the resistor patch is electrically connected to the first metal patch. The first metal patch includes an inner ring rectangular patch, an edge rectangular patch, and a mountain-shaped patch. The edge rectangular patch is connected to the corner of the inner ring rectangular patch through the rectangular patch, and the mountain-shaped patch is connected to the edge rectangular patch. The reflective layer includes a second dielectric substrate and a reflective unit disposed on the upper surface of the second dielectric substrate. The reflective unit includes a second metal patch with an annular slit.

[0006] To optimize the above technical solution, the specific limitations also include: The edge rectangular patch includes a first edge rectangular patch and a second edge rectangular patch; Furthermore, the first edge rectangular patch is symmetrically disposed on the outer side of one set of opposite corners of the inner ring rectangular patch, and the first edge rectangular patch is connected to the corresponding corner of the inner ring rectangular patch through the first rectangular patch; The second edge rectangular patch is symmetrically arranged on the outer side of another set of opposite corners of the inner ring rectangular patch, and the second edge rectangular patch is connected to the corresponding corner of the inner ring rectangular patch through the second rectangular patch.

[0007] The mountain-shaped patch includes a first mountain-shaped patch and a second mountain-shaped patch; Furthermore, the first mountain-shaped patch is connected to the first edge rectangular patch, and the second mountain-shaped patch is connected to the second edge rectangular patch.

[0008] The first mountain-shaped patch is composed of a first main branch and a first horizontal branch. One end of the first main branch is vertically connected to the middle of the first horizontal branch, and the other end of the first main branch is connected to the side of the first edge rectangular patch away from the inner ring rectangular patch. The first horizontal branch is parallel to the side of the first edge rectangular patch. The second mountain-shaped patch is composed of a second main branch and a second horizontal branch. One end of the second main branch is vertically connected to the middle of the second horizontal branch, and the other end of the second main branch is connected to the side of the second edge rectangular patch away from the inner ring rectangular patch. The second horizontal branch is parallel to the side of the second edge rectangular patch.

[0009] The number of resistor patches is four, and the four resistor patches are respectively disposed on the upper surface of the four sides of the inner ring rectangular patch, and the four resistor patches are distributed in a 90° rotational symmetry.

[0010] Furthermore, the inner ring rectangular patch, the edge rectangular patch, the mountain-shaped patch, and the rectangular patch are continuous patterns on the same metal layer.

[0011] The annular gap is parallel to the four sides of the second dielectric substrate and is rotationally symmetrical along the central normal.

[0012] Furthermore, the center of the annular gap coincides with the center of the second metal patch, and the width of the annular gap is 0.4 mm and the length is 10 mm.

[0013] The center of the inner ring rectangular patch coincides with the center of the first dielectric substrate, and the outer side of the inner ring rectangular patch has a length of 3.1 mm and a width of 0.5 mm.

[0014] Furthermore, the relative permittivity of the first dielectric substrate and the second dielectric substrate is 3.66, and the loss tangent is 0.004.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves high absorption over a wide frequency band by using a multimode resonant network composed of inner ring rectangular patches, edge rectangular patches, and mountain-shaped patches in the loss layer, combined with the Joule loss of the resistive patches. At the same time, by utilizing the annular gap in the reflective layer, a high-reflection notch frequency point is precisely generated within the absorption frequency band, successfully overcoming the technical problem that traditional frequency selective surfaces can only achieve single transmission or reflection and cannot simultaneously meet the requirements of integrated absorption and notch filtering.

[0016] This invention allows for arbitrary movement of the notch position within a wide absorption frequency band by adjusting the geometry of the gap, thereby adapting to the specific frequency requirements of different communication, radar, or IFF systems without changing the overall number of layers or substrate material. It offers a high degree of design freedom and is easy to implement in engineering.

[0017] In this invention, the resistive patch in the loss layer is primarily responsible for broadband energy dissipation, while the annular gap in the reflective layer independently generates notch reflection. The two are decoupled in phase by an air layer, allowing the absorption bandwidth and notch depth to be optimized separately without interference. The reflectivity increases sharply at the notch frequency, while the absorption rate in other frequency bands remains almost unaffected, resulting in stable and reliable cooperative performance.

[0018] This invention utilizes the multimode resonance effect formed by the inner ring, the edge rectangular patch, and the mountain-shaped patch, as well as the optimization of impedance matching by the air layer, to maintain a high absorption rate over a wide operating frequency band, with a relative bandwidth significantly greater than that of traditional single-resonant mode absorbers. Attached Figure Description

[0019] Figure 1 This is a side view of the frequency-selective absorber with notch characteristics according to the present invention.

[0020] Figure 2 This is a schematic diagram of the three-dimensional structure of the frequency-selective absorber with notch characteristics according to the present invention.

[0021] Figure 3 This is a schematic diagram of the loss unit structure in the frequency-selective absorber with notch characteristics of the present invention.

[0022] Figure 4 This is a schematic diagram of the reflective unit structure in the frequency-selective absorber with notch characteristics of the present invention.

[0023] Figure 5 The figure shows the simulation results of the frequency-selective absorber with notch characteristics according to the present invention.

[0024] In the figure: 1. Absorption unit; 2. First dielectric substrate; 3. Air layer; 4. Reflection unit; 5. Second dielectric substrate; 6. Resistor patch; 7. Inner ring rectangular patch; 8. First edge rectangular patch; 9. Second edge rectangular patch; 10. First mountain-shaped patch; 11. Second mountain-shaped patch; 12. First rectangular patch; 13. Second rectangular patch; 14. Annular gap. Detailed Implementation

[0025] The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0026] In the description of this invention, it should also be noted that: The orientations or positional relationships described herein are based on the relationships shown in the accompanying drawings and are only for the purpose of facilitating the description of the present invention and simplifying the description. They are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In this embodiment, for the sake of description, the orientation to the right in the figure is taken as the foreground.

[0027] Furthermore, terms such as "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise expressly specified and limited, terms such as "installation," "connection," or "joining" in this invention should be interpreted broadly, for example: they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections via an intermediate medium, or internal connections between two components.

[0028] Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] In some implementations, such as Figure 1 As shown, the present invention provides a frequency selective absorber with notch characteristics, which is provided with a loss layer, an air layer (3) and a reflection layer from top to bottom; The loss layer is mainly responsible for broadband dissipation absorption of incident electromagnetic waves. It includes a first dielectric substrate (2) and an absorption unit (1) disposed on the upper surface of the first dielectric substrate (2). The absorption unit (1) includes a first metal patch and a resistor patch (6). The resistor patch (6) is electrically connected to the first metal patch and is disposed on the upper surface of the first dielectric substrate (2). In some implementations, such as Figure 2As shown, the first metal patch includes an inner ring rectangular patch (7), an edge rectangular patch and a mountain-shaped patch. The edge rectangular patch is connected to the corner of the inner ring rectangular patch (7) through the rectangular patch, and the mountain-shaped patch is connected to the edge rectangular patch. The edge rectangular patch includes two first edge rectangular patches (8) and two second edge rectangular patches (9), which extend the current path length, introduce additional resonant modes, and thus broaden the absorption bandwidth; at the same time, they serve as transition structures to couple the inner loop current to the outer mountain-shaped patch, thereby achieving the superposition of multiple resonant modes.

[0030] The first edge rectangular patch (8) is symmetrically arranged on the outer side of one of the diagonals of the inner ring rectangular patch (7), and the first edge rectangular patch (8) is connected to the corresponding corner of the inner ring rectangular patch (7) through the first rectangular patch (12); The second edge rectangular patch (9) is symmetrically arranged on the outside of another set of opposite corners of the inner ring rectangular patch (7). The second edge rectangular patch (9) is connected to the corresponding corner of the inner ring rectangular patch (7) through the second rectangular patch (13).

[0031] In some embodiments, the inner ring rectangular patch (7) serves as the main electric field concentration area, generating a strong surface current under the excitation of incident electromagnetic waves. Its ring structure determines the fundamental resonant frequency, and its center coincides with the center of the first dielectric substrate (2). The outer side length of the inner ring rectangular patch (7) is a=3.1mm, and the width is wm=0.5mm.

[0032] The mountain-shaped patch includes two first mountain-shaped patches (10) and two second mountain-shaped patches (11); The first mountain-shaped patch (10) is connected to the first edge rectangular patch (8), and the second mountain-shaped patch (11) is connected to the second edge rectangular patch (9).

[0033] The first mountain-shaped patch (10) is composed of a first main branch and a first horizontal branch. One end of the first main branch is vertically connected to the middle of the first horizontal branch, and the other end of the first main branch is connected to the side of the first edge rectangular patch (8) away from the inner ring rectangular patch (7). The first horizontal branch is parallel to the side of the first edge rectangular patch (8). The second mountain-shaped patch (11) is composed of a second main branch and a second horizontal branch. One end of the second main branch is vertically connected to the middle of the second horizontal branch, and the other end of the second main branch is connected to the side of the second edge rectangular patch (9) away from the inner ring rectangular patch (7). The second horizontal branch is parallel to the side of the second edge rectangular patch (9).

[0034] Due to its T-shaped or mountain-shaped branch structure, the mountain-shaped patch can generate multiple local current standing wave nodes, significantly increasing the equivalent inductance and capacitance, thereby introducing additional absorption poles at higher frequencies. By adjusting its branch length, the high-frequency absorption edge can be precisely controlled, making the entire absorption band flatter and wider.

[0035] In some implementations, the inner ring rectangular patch (7), the two first edge rectangular patches (8), the two second edge rectangular patches (9), the two first mountain-shaped patches (10), the two second mountain-shaped patches (11), the two first rectangular patches (12), and the two second rectangular patches (13) are an integral structure of continuous patterns on the same metal layer, ensuring low contact resistance and structural stability.

[0036] The long side a1 of the first edge rectangular patch (8) is 4mm, and the short side a2 is 4mm. The second edge rectangular patch (9) is the same as the first edge rectangular patch (8). The first long side L1 of the first mountain-shaped patch (10) is 2.8mm, the second long side L3 is 2.5mm, and the bottom horizontal length L2 is 2.4mm. The second mountain-shaped patch (11) is the same as the first mountain-shaped patch (10). Figure 3 As shown.

[0037] There are four resistor patches (6). The four resistor patches (6) are respectively set on the upper surface of the four sides of the inner ring rectangular patch (7), and the four resistor patches (6) are distributed in a 90° rotational symmetry.

[0038] In some implementations, the four resistive patches (6) have a resistance of 220 ohms. When the electromagnetic wave excites the surface current, the current flows through the resistive patches and generates Joule heat, thereby converting the electromagnetic energy into heat energy and dissipating it. The four symmetrically distributed resistors ensure that energy is absorbed uniformly regardless of the polarization direction of the incident wave, achieving polarization insensitivity.

[0039] The reflective layer is mainly used to provide a total reflection background and introduce frequency selection characteristics through the annular slit (14) on it to form a specific notch frequency. It includes a second dielectric substrate (5) and a reflective unit (4) disposed on the upper surface of the second dielectric substrate (5). The reflective unit (4) includes a second metal patch with an annular slit (14) on it.

[0040] The annular gap (14) is parallel to the four sides of the second dielectric substrate (5) and is rotationally symmetrical along the central normal.

[0041] In some implementations, such as Figure 4 As shown, the center of the annular gap (14) coincides with the center of the second metal patch. The gap width of the annular gap (14) is d=0.4mm and the gap length is a4=10mm.

[0042] In some implementations, the annular slot structure is equivalent to an electrically small loop antenna, generating strong magnetic dipole resonances near a specific frequency (determined by the slot perimeter). At this resonant frequency, the slot allows some electromagnetic energy to penetrate the reflective layer (i.e., the reflection coefficient amplitude decreases, and transmission increases), but because there is still an absorbing structure above the loss layer, the actual behavior is that the total reflectivity of the absorber at this frequency increases sharply (i.e., notch wave). The annular slot disrupts the absorption conditions, causing the absorber to refuse absorption at this frequency and strongly reflect electromagnetic waves, thus forming a notch wave characteristic.

[0043] Both the first dielectric substrate 2 and the second dielectric substrate 5 are square plates with a relative permittivity of 3.66 and a loss tangent of 0.004. The side length of the first dielectric substrate 2 and the second dielectric substrate 5 is p = 16 mm, and the thickness is t = 0.8 mm. An air layer, serving as a spacer, is used to adjust the electromagnetic coupling strength between the loss layer and the reflective layer and affects the overall resonance characteristics; its thickness is h = 7 mm. Figure 1 and 3 As shown.

[0044] In some implementations, the loss layer converts incident electromagnetic energy into Joule heat through resistive patches (6), achieving broadband absorption; the annular slit (14) of the reflective layer generates strong reflection at a specific frequency, disrupting the absorption conditions, thereby creating a high-reflection window (i.e., notch characteristics) within the absorption band. The thickness of the air layer (3) can be independently adjusted to optimize the balance between absorption bandwidth and notch depth. The three work together to enable the absorber to maintain a high absorption rate within a wide frequency band while achieving near total reflection at a specified frequency, meeting the integrated requirements of radar stealth and communication band wave transmission.

[0045] In some implementations, the absorptivity of the frequency-selective absorber with notch characteristics is simulated using commercial simulation software, and the results are as follows: Figure 5 As shown. From Figure 5 As can be seen from the present invention, the frequency-selective absorber with notch characteristics proposed in this invention can achieve absorption in the 4.22GHz~5.69GHz frequency band with a loss rate of over 80%. At the same time, it can achieve strong reflection at specific frequency points, thus realizing notch characteristics.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A frequency-selective absorber with notch characteristics, characterized in that, From top to bottom, there are a loss layer, an air layer, and a reflective layer; The loss layer includes a first dielectric substrate and an absorption unit disposed on the upper surface of the first dielectric substrate. The absorption unit includes a first metal patch and a resistor patch, and the resistor patch is electrically connected to the first metal patch. The first metal patch includes an inner ring rectangular patch, an edge rectangular patch, and a mountain-shaped patch. The edge rectangular patch is connected to the corner of the inner ring rectangular patch through the rectangular patch, and the mountain-shaped patch is connected to the edge rectangular patch. The reflective layer includes a second dielectric substrate and a reflective unit disposed on the upper surface of the second dielectric substrate. The reflective unit includes a second metal patch with an annular slit.

2. The frequency-selective absorber with notch characteristics according to claim 1, characterized in that: The edge rectangular patch includes a first edge rectangular patch and a second edge rectangular patch; The first edge rectangular patch is symmetrically arranged on the outer side of one set of opposite corners of the inner ring rectangular patch, and the first edge rectangular patch is connected to the corresponding corner of the inner ring rectangular patch through the first rectangular patch; The second edge rectangular patch is symmetrically arranged on the outer side of another set of opposite corners of the inner ring rectangular patch, and the second edge rectangular patch is connected to the corresponding corner of the inner ring rectangular patch through the second rectangular patch.

3. A frequency-selective absorber with notch characteristics according to claim 2, characterized in that: The mountain-shaped patch includes a first mountain-shaped patch and a second mountain-shaped patch; The first mountain-shaped patch is connected to the first edge rectangular patch, and the second mountain-shaped patch is connected to the second edge rectangular patch.

4. A frequency-selective absorber with notch characteristics according to claim 3, characterized in that: The first mountain-shaped patch is composed of a first main branch and a first horizontal branch. One end of the first main branch is vertically connected to the middle of the first horizontal branch, and the other end of the first main branch is connected to the side of the first edge rectangular patch away from the inner ring rectangular patch. The first horizontal branch is parallel to the side of the first edge rectangular patch. The second mountain-shaped patch is composed of a second main branch and a second horizontal branch. One end of the second main branch is vertically connected to the middle of the second horizontal branch, and the other end of the second main branch is connected to the side of the second edge rectangular patch away from the inner ring rectangular patch. The second horizontal branch is parallel to the side of the second edge rectangular patch.

5. A frequency-selective absorber with notch characteristics according to claim 1, characterized in that: The number of resistor patches is four, and the four resistor patches are respectively disposed on the upper surface of the four sides of the inner ring rectangular patch, and the four resistor patches are distributed in a 90° rotational symmetry.

6. A frequency-selective absorber with notch characteristics according to claim 1, characterized in that: The inner ring rectangular patch, the edge rectangular patch, the mountain-shaped patch, and the rectangular patch are continuous patterns on the same metal layer.

7. A frequency-selective absorber with notch characteristics according to claim 1, characterized in that: The annular gap is parallel to the four sides of the second dielectric substrate and is rotationally symmetrical along the central normal.

8. A frequency-selective absorber with notch characteristics according to claim 1, characterized in that: The center of the annular gap coincides with the center of the second metal patch. The width of the annular gap is 0.3mm~0.5mm and the length is 9mm~10mm.

9. A frequency-selective absorber with notch characteristics according to claim 1, characterized in that: The center of the inner ring rectangular patch coincides with the center of the first dielectric substrate, and the outer side length of the inner ring rectangular patch is 3.0mm~3.5mm, and the width is 0.4mm~0.6mm.

10. A frequency-selective absorber with notch characteristics according to claim 1, characterized in that: The relative permittivity of the first dielectric substrate and the second dielectric substrate is 3.5~3.8, and the loss tangent is 0.003~0.005.

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