A square structure based dual-polarized frequency selective absorption aperture

Abstract

The application discloses a kind of square structure-based dual polarization frequency selective absorption aperture array;It relates to the technical field of frequency selective wave-absorbing structure, including a plurality of dense array arrangement square hole, each square hole is surrounded by four rectangular frequency selective absorption body unit splicing, the long side of adjacent two frequency selective absorption units is spliced with each other, and the frequency selective absorption unit between adjacent two square holes is oppositely arranged;Frequency selective absorption unit is divided into upper and lower parts along the length direction, the upper part is provided with carbon loss circuit for absorbing incident electromagnetic wave, and the lower part is provided with multi-frequency point resonance structure for frequency selection;The upper part and the lower part of adjacent two frequency selective absorption units are not connected;The application has the ability of simultaneously frequency selection and absorption to X polarized electromagnetic wave and Y polarized electromagnetic wave, and the frequency selective absorption response of dual polarization presents high consistency;At the same time, it has air convection channel, which significantly improves the heat dissipation capacity;It can be widely applied to various engineering scenes.

Description

Technical Field

[0001] This application relates to the field of frequency selective absorbing structure technology, and in particular to a dual-polarized frequency selective absorbing aperture array based on a square structure. Background Technology

[0002] Frequency-selective absorbers are a class of composite electromagnetic structures capable of simultaneously achieving "highly efficient transmission in a specific frequency band and good absorption in other frequency bands" on a single aperture surface. Unlike traditional frequency-selective surfaces that can only reflect or transmit, frequency-selective absorbers convert out-of-band electromagnetic wave energy into heat energy by introducing a loss mechanism, thereby avoiding secondary scattering or system self-interference problems caused by out-of-band reflection. Since its introduction in the early 21st century, frequency-selective absorbers have received widespread attention in fields such as radar stealth radomes, electromagnetic compatibility shielding, and low-observable platforms, becoming one of the hot research directions in electromagnetic metamaterials.

[0003] In engineering implementation, typical frequency-selective absorbers usually employ a cascaded "absorbing layer + frequency-selective layer" approach. The absorbing layer generally uses periodic cells with lumped resistance or a uniform carbon loss coating, responsible for absorbing out-of-band electromagnetic waves; the frequency-selective layer consists of metal patches or slotted apertures, responsible for controlling the transmission response within the passband. While this layered design approach achieves the basic function, it often leads to an increase in the overall structural thickness and a more complex manufacturing process. More importantly, existing designs have long suffered from an irreconcilable conflict between heat dissipation capacity, polarization adaptation, wide-angle stability, and structural simplicity. Summary of the Invention

[0004] To achieve a dual-polarized frequency-selective absorbing structure, this application provides a dual-polarized frequency-selective absorbing aperture array based on a square structure.

[0005] This application provides a dual-polarization frequency-selective absorption aperture array based on a square structure, employing the following technical solution:

[0006] A dual-polarization frequency selective absorption aperture array based on a square structure is characterized in that: it includes a number of square apertures arranged in a dense array, each square aperture is formed by splicing four rectangular frequency selective absorber units, the long sides of two adjacent frequency selective absorber units are spliced ​​together, and the frequency selective absorber units between two adjacent square apertures are arranged opposite each other.

[0007] The frequency selective absorption unit is divided into upper and lower parts along its length. The upper part is equipped with a carbon loss circuit for absorbing incident electromagnetic waves, and the lower part is equipped with a multi-frequency resonant structure for frequency selection. The upper and lower parts of two adjacent frequency selective absorption units are not connected.

[0008] Optionally, the frequency selective absorption unit includes a dielectric substrate and a metal functional layer covering the dielectric substrate; in a single square hole, the outer layer is a metal functional layer and the inner layer is a dielectric substrate; the carbon loss circuit and the multi-frequency resonant structure are disposed on the metal functional layer.

[0009] Optionally, the upper part of the metal functional layer is provided with a concave groove, and the two protruding parts of the concave groove are connected to the side wall of the metal functional layer and are provided with carbon paste.

[0010] Five elongated slots are arranged in parallel and spaced apart between the two protrusions. The five elongated slots are symmetrically arranged along the axis of the length of the metal functional layer. The elongated slot in the middle connects the concave slot with the side wall of the metal functional layer. The two elongated slots near the two protrusions on both sides of the concave slot connect with the concave slot, and the other two elongated slots connect with the side wall of the metal functional layer.

[0011] The carbon loss circuit consists of carbon paste, a meandering metal strip at the top of the concave slot, and strip-shaped metal strips on both sides of the concave slot.

[0012] Optionally, except for the elongated slot located in the middle, the other elongated slots are of equal length.

[0013] Optionally, the lower part of the metal functional layer has an I-shaped groove, two horizontal grooves, and four F-shaped grooves; the bottom of the four F-shaped grooves are respectively connected to the ends of each horizontal segment of the I-shaped groove, and the pattern formed after connection is a centrally symmetrical pattern; the two horizontal grooves are arranged at intervals along the width direction of the metal functional layer and are symmetrically arranged about the central axis in the length direction; the two horizontal grooves are respectively arranged between the two F-shaped grooves and are equidistant from the two F-shaped grooves; the multi-frequency resonant structure is composed of horizontal grooves, F-shaped grooves, and I-shaped grooves.

[0014] Optionally, the two horizontal segments of the F-shaped groove are of equal length, and one of the horizontal segments is located in the middle of the vertical segment.

[0015] Optionally, the length of the transverse groove is greater than the length of the transverse segment of the F-shaped groove, and the distance between the transverse groove and the rib of the I-shaped groove is equal to the distance between the F-shaped groove and the rib of the I-shaped groove.

[0016] In summary, this application includes the following beneficial technical effects:

[0017] The aforementioned dual-polarization frequency-selective absorbing structure possesses the ability to simultaneously select and absorb X-polarized and Y-polarized electromagnetic waves, and the dual-polarization frequency-selective absorption response exhibits high consistency. Furthermore, it features an air convection channel, significantly enhancing heat dissipation. In addition, its simple structure, ease of fabrication, convenient use, and low cost make it widely applicable in fields such as aircraft stealth, high-power radar radomes, satellite communication terminals, new energy vehicle radar, IoT devices, and UAV data link systems. It is particularly suitable for engineering scenarios that demand high levels of heat dissipation performance, stealth characteristics, dual-polarization features, and low-cost mass production. Attached Figure Description

[0018] Figure 1 This is an overall schematic diagram of a dual-polarized frequency-selective absorbing structure in one embodiment;

[0019] Figure 2 A front view of a frequency selective absorbing unit of a dual-polarized frequency selective absorbing structure in one embodiment;

[0020] Figure 3 This is a side view of a frequency selective absorbing unit of a dual-polarized frequency selective absorbing structure in one embodiment;

[0021] Figure 4 This is a top view of a frequency selective absorbing unit of a dual-polarized frequency selective absorbing structure in one embodiment;

[0022] Figure 5 This is an S-parameter curve of the frequency selective absorbing unit of a dual-polarized frequency selective absorbing structure for an X-polarized incident wave in one embodiment.

[0023] Figure 6 This is an S-parameter curve of the frequency selective absorbing unit of a dual-polarized frequency selective absorbing structure for a Y-polarized incident wave in one embodiment.

[0024] Figure 7 This is a graph showing the absorption rate of a frequency-selective absorbing unit of a dual-polarized frequency-selective absorbing structure for a Y-polarized incident wave in one embodiment.

[0025] Figure 8 The diagram shows the S-curve parameters of a dual-polarized frequency-selective absorbing structure for an X-polarized incident wave in one embodiment.

[0026] Figure 9 The diagram shows the S-curve parameters of a dual-polarized frequency-selective absorbing structure for an X-polarized incident wave in one embodiment.

[0027] Figure 10 This is a graph showing the absorption rate of a dual-polarized frequency-selective absorbing structure for X-polarized and Y-polarized incident waves in one embodiment.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Metal functional layer; 2. Dielectric substrate; 3. Carbon paste; 4. Winding metal strip; 5. Strip metal strip. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1-10 This application will be described in further detail.

[0031] This application discloses a dual-polarization frequency selective absorption aperture array based on a square structure; the absorption aperture array consists of a number of densely arranged square apertures, each square aperture is formed by splicing four rectangular frequency selective absorber units, the long sides of two adjacent frequency selective absorber units are spliced ​​together, and the frequency selective absorber units between two adjacent square apertures are arranged opposite each other.

[0032] The frequency selective absorption unit includes a dielectric substrate and a metal functional layer covering the dielectric substrate; in a single square hole, the outer layer is a metal functional layer and the inner layer is a dielectric substrate; the carbon loss circuit and the multi-frequency resonant mechanism are disposed on the metal functional layer.

[0033] The frequency selective absorption unit is divided into upper and lower parts along its length. The upper part is equipped with a carbon loss circuit for absorbing incident electromagnetic waves, and the lower part is equipped with a multi-frequency resonant structure for frequency selection. The upper and lower parts of two adjacent frequency selective absorption units are not connected.

[0034] The above settings can achieve dual polarization; when there are two or more square holes, the square hole array is set (e.g., forming a linear array or a square array) to improve the frequency selection performance (characterized by S11, S21) and absorption performance (characterized by absorption rate), avoid introducing additional interference, avoid causing secondary electromagnetic radiation, and avoid leakage of electromagnetic waves.

[0035] Specifically, the carbon loss circuit consists of carbon paste, a meandering metal strip at the top of the concave slot, and strip metal strips on both sides of the concave slot.

[0036] The upper part of the metal functional layer has a concave groove, and the two protruding parts of the concave groove are connected to the side wall of the metal functional layer and are provided with carbon paste.

[0037] Five elongated slots are arranged in parallel and spaced intervals between the two protruding parts. The five elongated slots are symmetrically arranged along the axis of the metal functional layer. The middle elongated slot connects the concave slot to the side wall of the metal functional layer. The two elongated slots on the two protruding sides near the concave slot connect to the concave slot. The other two elongated slots connect to the side wall of the metal functional layer. After these five slots are cut in the metal functional layer, a meandering metal strip is formed at the top and strip-shaped metal strips are formed on both sides. Except for the middle elongated slot, the other elongated slots are of equal length. The above arrangement can change the current response and current excitation, thereby improving the absorption performance.

[0038] The lower part of the metal functional layer has an I-shaped groove, two horizontal grooves, and four F-shaped grooves. The bottom of the four F-shaped grooves is connected to the ends of the horizontal segments of the I-shaped grooves, forming a centrally symmetrical pattern. The two horizontal grooves are spaced apart along the width of the metal functional layer and are symmetrically arranged about the central axis in the length direction. The two horizontal grooves are respectively located between the two F-shaped grooves and are equidistant from the two F-shaped grooves. The multi-frequency resonant structure is composed of the I-shaped groove, the F-shaped groove, and the horizontal grooves. The two horizontal segments of the F-shaped groove are of equal length, and one of the horizontal segments is located in the middle of the vertical segment. The length of the horizontal groove is greater than the length of the horizontal segment of the F-shaped groove, and the distance between the horizontal groove and the rib of the I-shaped groove is equal to the distance between the F-shaped groove and the rib of the I-shaped groove.

[0039] The F-shaped structure design introduces three additional resonant frequencies in the 5G to 15G frequency band for the frequency-selective absorption unit: two at low frequencies and three at high frequencies, thereby improving the absorption efficiency of the unit at both high and low frequencies.

[0040] The working process of this application embodiment is as follows: when the frequency-selective absorbing unit is placed horizontally, the incident Y-polarized electromagnetic wave will be frequency-selected and absorbed by the frequency-selective absorbing unit.

[0041] When the frequency-selective absorbing unit is placed vertically, the incident X-polarized electromagnetic wave will be frequency-selected and absorbed by the frequency-selective absorbing unit.

[0042] When the frequency-selective absorbing units are placed vertically and the resulting frequency-selective absorbing component array is set, the width direction of the functional area is the electromagnetic wave incident direction. In the electromagnetic wave incident absorption area, a first patch made of metal and a second patch made of carbon are connected to form a carbon loss circuit to resistively absorb the incident electromagnetic waves outside the gateband. Electromagnetic waves within the gateband are emitted from the absorption area and incident on the selection area. After passing through the multi-frequency resonant structure formed by the slots, they resonate and are emitted, realizing the frequency-selective absorption function and the bandpass gating characteristic (two frequency-selective absorbing units placed horizontally can handle Y-polarized electromagnetic waves; two frequency-selective absorbing units placed vertically can handle X-polarized electromagnetic waves; four frequency-selective absorbing units form a frequency-selective absorbing component to realize the dual-polarized frequency-selective absorption characteristic).

[0043] When electromagnetic waves are incident, those that coincide with the absorption frequency band form a closed loop and are consumed by heat; those that coincide with the selective frequency point enter the selective region and then propagate out through the selective region.

[0044] The aforementioned dual-polarization frequency-selective absorbing structure possesses the ability to simultaneously select and absorb both X-polarized and Y-polarized electromagnetic waves, with a highly consistent frequency-selective absorption response. It also features air convection channels, significantly enhancing heat dissipation. Furthermore, its simple structure, ease of fabrication, convenient use, and low cost make it widely applicable in fields such as aircraft stealth, high-power radar radomes, satellite communication terminals, new energy vehicle radar, IoT devices, and UAV data link systems. It is particularly suitable for engineering scenarios with high requirements for heat dissipation performance, stealth characteristics, dual-polarization features, and low-cost mass production. This frequency-selective absorbing structure has two absorption bands at low and high frequencies. When two electromagnetic waves probe, most of the energy is absorbed by the structure, resulting in very low electromagnetic wave reflection efficiency, making it difficult to detect the structure through reflected echoes, thus achieving stealth characteristics.

[0045] In one specific embodiment, the dielectric layer is made of FR4 material (dielectric constant of 4.3, loss tangent of 0.02), and has a rectangular structure with a length of 21 mm, a width of 11 mm, and a thickness of 1 mm; the functional layer is made of copper as the metallic material and carbon as the non-metallic material (sheet resistance of 80 Ω).

[0046] The dual-polarization frequency-selective absorption unit and dual-polarization frequency-selective absorption structure were simulated, analyzed, and optimized using the electromagnetic full-wave simulation software CST. The S-parameters of the frequency-selective absorption unit, the absorption rate of the frequency-selective absorption unit for Y-polarized electromagnetic waves, the S-parameters of the frequency-selective absorption structure, and the absorption rates of the frequency-selective absorption structure for X-polarized and Y-polarized electromagnetic waves were studied.

[0047] like Figure 5 and Figure 6As shown, when the frequency selective absorption unit is placed horizontally, it exhibits frequency selectivity for Y-polarized incident electromagnetic waves. Its operating bandwidth is 9.22GHz-10.01GHz. Within the entire operating frequency band, S11 is less than -10dB, reaching a minimum of -33dB, while S21 approaches -1dB within the operating frequency band. This demonstrates that the frequency selective absorption unit has excellent frequency selectivity. A single frequency selective absorption unit only exhibits single-polarization characteristics, and when placed horizontally, it only has frequency selective absorption for Y-polarized electromagnetic waves.

[0048] like Figure 7 As shown, when the frequency selective absorption unit is placed horizontally, it exhibits frequency selective absorption characteristics for Y-polarized incident electromagnetic waves. The absorption rate is around 0.2 in the operating bandwidth of 9.22GHz-10.01GHz, indicating that most electromagnetic waves are successfully radiated within the operating bandwidth. The absorption rate is mostly above 0.9 on both sides of the operating frequency band, indicating that most electromagnetic waves are absorbed by the frequency selective absorption unit, proving that the frequency selective absorption unit has excellent frequency selective absorption capability.

[0049] like Figure 8 and Figure 9 As shown, the S11 and S21 curves of the frequency selective absorption structure exhibit high consistency under the incident conditions of X-polarized and Y-polarized electromagnetic waves, proving that the frequency selective absorption structure can simultaneously handle electromagnetic waves of these two polarizations. Due to array coupling, the operating bandwidth of the frequency selective absorption structure is slightly wider and shifts to higher frequencies compared to the frequency selective absorption unit. The operating bandwidth of this frequency selective absorption structure is 9.60GHz-10.29GHz. Within the entire operating frequency band, for both X-polarized and Y-polarized incident waves, S11 is below -10dB, while S21 approaches -1dB within the operating frequency band, demonstrating the superior frequency selectivity of this frequency selective absorption structure for both X-polarized and Y-polarized incident waves.

[0050] like Figure 10 As shown, the frequency-selective absorption structure exhibits frequency-selective absorption characteristics for both X-polarized and Y-polarized incident electromagnetic waves. Due to array coupling, the absorption rate of the frequency-selective absorption structure at the operating bandwidth is slightly higher than that of the frequency-selective absorption unit. The absorption rate is around 0.3 in the operating bandwidth of 9.60 GHz-10.29 GHz, indicating that most electromagnetic waves are successfully radiated within the operating bandwidth. The absorption rates on both sides of the operating frequency band are mostly above 0.9, indicating that most electromagnetic waves are absorbed by the frequency-selective absorption unit. At the same time, the absorption curves of the two polarizations are highly consistent, proving that the frequency-selective absorption structure has dual-polarization frequency-selective absorption capability.

[0051] In summary, this application has the following beneficial effects:

[0052] 1. A frequency-selective absorbing unit was designed and formed into a frequency-selective absorbing component. It can achieve frequency selection and absorption of X-polarization and Y-polarization without complex multi-layer asymmetric units. At the same time, it achieves equivalent processing of X-polarization and Y-polarization, and has balanced dual-polarization characteristics. The polarization response (including key performance indicators such as the center frequency of the transmission band, absorption rate, and insertion loss) under the two polarization modes is almost completely consistent. It can work stably in complex electromagnetic environments where the polarization state of electromagnetic waves changes randomly.

[0053] 2. It can achieve stable absorption and gating of incident electromagnetic waves, improving the stability of wave transmission and absorption. A carbon loss circuit is constructed using carbon materials, meandering metal microstrip lines, and vertical metal microstrip lines to achieve absorption bands at both low and high frequencies. The design process considers high symmetry, selecting a square aperture structure with high symmetry to design the frequency-selective absorbing component, improving the overall structure's wide-angle incident stability. Frequency selection at 10GHz is achieved by vertically slotting a rectangular metal sheet. Furthermore, by adding four F-shaped slots and two horizontal slots, four additional resonant frequencies are introduced into the low- and high-frequency absorption bands, improving the absorption efficiency and bandwidth of both bands.

[0054] 3. The operating frequency band is 9.60GHz-10.29GHz, with an in-band absorptivity of 0.3 and an out-of-band absorptivity mostly above 0.9, significantly better than the 0.8 out-of-band absorptivity of existing technologies, achieving excellent frequency-selective absorption characteristics. A carbon loss circuit is constructed using carbon materials, meandering metal microstrip lines, and vertical metal microstrip lines to achieve absorption bands at both low and high frequencies. The design process considers high symmetry, selecting a square aperture structure with high symmetry to design the frequency-selective absorbing component, improving the wide-angle incident stability of the entire structure. Frequency selectivity at 10GHz is achieved by vertically slotting a rectangular metal sheet. Furthermore, by adding four F-shaped slots and two horizontal slots, four additional resonant frequencies are introduced into the low- and high-frequency absorption bands, improving the absorption efficiency and bandwidth of both bands.

[0055] 4. Instead of using the traditional independent layered cascade method, the absorption function (carbon loss circuit) and frequency selection function (slotted resonance) are integrated into different areas of the same functional layer. This design achieves integrated absorption and gating, which not only reduces the overall thickness and number of layers and reduces the processing difficulty, but also avoids the impact of interlayer alignment errors on performance, which is conducive to stable mass production.

[0056] 5. The frequency selective absorbing component formed by four frequency selective absorbing units is a hollow tubular structure, and the frequency selective absorbing structure formed by the array of multiple frequency selective absorbing components is a square hole periodic structure. It can form an open heat dissipation channel in high-power, long-term continuous operation scenarios (such as radar radomes and communication base stations), effectively reducing the internal temperature rise of the structure, improving heat dissipation performance, ensuring the dielectric properties of the material and the stability of the loss layer, thereby improving the reliability and lifespan of the system. It avoids the air blockage problem of closed metal patches or continuous ground layers in traditional frequency selective absorbing bodies, solves the heat dissipation bottleneck problem in high-power operation scenarios, and provides a natural convection channel for air convection and heat dissipation.

[0057] 6. The overall structure consists of only one functional layer and one dielectric layer. It does not require lumped resistance welding, multi-layer high-precision alignment, or special high-cost materials. It can be processed using conventional PCB technology, which significantly reduces manufacturing costs and process barriers, making it suitable for large-scale industrial production and equipment promotion.

[0058] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A dual-polarization frequency-selective absorption aperture array based on a square structure, characterized in that: It includes several square holes arranged in a dense array. Each square hole is surrounded by four rectangular frequency selective absorber units spliced ​​together. The long sides of two adjacent frequency selective absorber units are spliced ​​together, and the frequency selective absorber units between two adjacent square holes are set opposite to each other. The frequency selective absorption unit is divided into upper and lower parts along its length. The upper part is equipped with a carbon loss circuit for absorbing incident electromagnetic waves, and the lower part is equipped with a multi-frequency resonant structure for frequency selection. The upper and lower parts of two adjacent frequency selective absorption units are not connected.

2. The dual-polarization frequency-selective absorption aperture array based on a square structure according to claim 1, characterized in that: The frequency selective absorption unit includes a dielectric substrate and a metal functional layer covering the dielectric substrate; in each of the square holes, the outer layer is a metal functional layer and the inner layer is a dielectric substrate; the carbon loss circuit and the multi-frequency resonant structure are disposed on the metal functional layer.

3. The dual-polarization frequency-selective absorption aperture array based on a square structure according to claim 2, characterized in that: The upper part of the metal functional layer is provided with a concave groove, and the two protruding parts of the concave groove are connected to the side wall of the metal functional layer and are provided with carbon paste. Five elongated slots are arranged in parallel and spaced apart between the two protrusions. The five elongated slots are symmetrically arranged along the axis of the length of the metal functional layer. The elongated slot in the middle connects the concave slot with the side wall of the metal functional layer. The two elongated slots near the two protrusions on both sides of the concave slot connect with the concave slot, and the other two elongated slots connect with the side wall of the metal functional layer. The carbon loss circuit consists of carbon paste, a meandering metal strip at the top of the concave slot, and strip-shaped metal strips on both sides of the concave slot.

4. The dual-polarization frequency-selective absorption aperture array based on a square structure according to claim 3, characterized in that: Except for the elongated slot in the middle, the other elongated slots are of equal length.

5. The dual-polarization frequency-selective absorption aperture array based on a square structure according to claim 2, characterized in that: The lower part of the metal functional layer has an I-shaped groove, two horizontal grooves, and four F-shaped grooves; the bottom of the four F-shaped grooves are connected to the ends of the horizontal segments of the I-shaped grooves, and the pattern formed after the connection is a centrally symmetrical pattern; the two horizontal grooves are arranged at intervals along the width direction of the metal functional layer and are symmetrically arranged about the central axis in the length direction; the two horizontal grooves are respectively arranged between the two F-shaped grooves and are equidistant from the two F-shaped grooves; the multi-frequency resonant structure is composed of horizontal grooves, F-shaped grooves, and I-shaped grooves.

6. The dual-polarization frequency-selective absorption aperture array based on a square structure according to claim 5, characterized in that: The two horizontal segments of the F-shaped groove are of equal length, and one of the horizontal segments is located in the middle of the vertical segment.

7. A dual-polarization frequency-selective absorption aperture array based on a square structure according to claim 6, characterized in that: The length of the horizontal groove is greater than the length of the horizontal segment of the F-shaped groove, and the distance between the horizontal groove and the rib of the I-shaped groove is equal to the distance between the F-shaped groove and the rib of the I-shaped groove.

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