High power frequency selective surface heat sink structure with folded line coupling arms and method

Abstract

The application discloses a high-power frequency selective surface heat dissipation structure with a fold line coupling arm and a method, and belongs to the field of electromagnetic wave-transparent frequency selective surface design. The structure comprises a plurality of metal frequency selective units arranged in a periodic array on a metal layer; the metal frequency selective unit is a square region with a side length of 8 mm; a peripheral metal is a square frame arranged circumferentially around the region, with a width of 0.05 mm; a square metal patch with a side length of 5 mm is arranged at the center; and a fold line coupling arm is arranged at each of the four corners of the metal patch. The two metal wire segments of the fold line coupling arm each have a length of 1.65 mm and a width of 0.1 mm. The fold line coupling arm structure is introduced around the metal patch to construct a controlled electromagnetic coupling path, current density redistribution and heat source dispersion are achieved, and the thermal stability and power bearing capacity of the frequency selective surface are improved without changing the material system and adding additional heat dissipation structures.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave absorption frequency selective surface design, specifically relating to a high-power frequency selective surface heat dissipation structure and method with a zigzag coupling arm. Background Technology

[0002] Frequency Selective Surfaces (FSS) are a type of electromagnetic functional structure based on a periodic array of metals. Their fundamental principle stems from the resonant response characteristics of periodic structures to electromagnetic waves. By arranging metal units with specific geometries on a dielectric substrate according to a certain period, the structure can selectively transmit or reflect electromagnetic waves within a specific frequency range. This type of structure plays a crucial role in radar radome design, satellite communication antenna housings, electromagnetic compatibility shielding structures, stealth technology, and next-generation mobile communication systems. Especially in the aerospace and military equipment fields, FSSs not only perform frequency filtering but also need to meet multiple performance requirements, including structural load-bearing capacity, environmental adaptability, and long-term reliability.

[0003] In electromagnetic operation, incident electromagnetic waves induce currents in the FSS metal unit, forming resonant modes coupled with the incident field. For patch or slotted structures, the current is typically concentrated along the metal edge or in narrow areas, with the peak current density increasing as the resonant frequency approaches the design frequency. Due to the finite resistance of the metal conductor, this high-density current inevitably generates Joule heating. Simultaneously, the dielectric substrate experiences polarization hysteresis under alternating electric fields, leading to dielectric loss and its conversion into heat. In low-power applications, this heat can dissipate through natural convection or conduction, having a limited impact on the overall structure. However, under high-power microwave irradiation, the increase in current density is nonlinear, causing a rapid rise in temperature in localized areas and the formation of significant hot spots.

[0004] The generation of hotspots not only affects the thermal safety of the structure but also alters the electromagnetic parameters of the materials. The dielectric constant of dielectric materials typically drifts with temperature, and the resistivity of metals increases with temperature, further changing the resonance conditions and causing a shift in the electromagnetic response. Changes in electromagnetic properties can then lead to current refocusing, resulting in a thermo-electric positive feedback effect. Under extreme conditions, local temperatures may exceed the substrate's heat resistance limit, causing problems such as material aging, carbonization, warping, or metal layer detachment, which can severely lead to transmission failure or structural damage. In environments such as hypersonic vehicles and airborne radar systems, the FSS must also withstand the combined effects of aerodynamic and electromagnetic heating, making its thermal reliability even more critical.

[0005] To address the aforementioned issues, existing technologies primarily focus on two approaches: material improvement and enhanced external heat dissipation. One approach is to utilize high thermal conductivity materials or composite materials to improve heat diffusion; another is to add additional structures such as heat sinks, metal backplates, and cooling channels to dissipate heat. However, these measures often increase system weight and structural complexity, and may alter electromagnetic boundary conditions, leading to resonant frequency shifts or decreased transmission performance. The applicability of these methods is limited in applications highly sensitive to size, weight, and electromagnetic performance. Furthermore, high-performance thermally conductive materials are expensive and require complex processing, hindering large-scale deployment.

[0006] It is worth noting that the current distribution on a frequency-selective surface is essentially determined by the geometry of the metal elements. The size, edge shape, gap structure, and topological layout of the metal elements directly affect the current path and the electric field concentration region, thus determining the power density distribution. However, in traditional designs, structural optimization usually revolves around resonant frequency, bandwidth, and polarization stability, rarely considering thermal behavior as an initial design constraint. Common square patches, ring elements, or cross structures often exhibit significant current concentration regions in the resonant state, and this concentration phenomenon becomes a major cause of thermal failure under high power conditions. Although some research has begun to focus on electromagnetic-thermal coupling issues, most remain at the analytical level, lacking systematic solutions for improving thermal performance by controlling the current distribution through the structure itself.

[0007] Therefore, while maintaining the original material system and structural thickness, adjusting the topology of the metal units to rationally extend and disperse the current path, thereby reducing local power density at the source, becomes a more engineering-valuable solution. This approach differs from simply enhancing heat dissipation; instead, it reduces hotspot generation by altering the energy distribution pattern, thus achieving a balance between electromagnetic and thermal performance. How to achieve current redistribution without introducing new strong parasitic resonances or significantly altering frequency response characteristics is a crucial problem that urgently needs to be addressed in current frequency-selective surface structure design. Summary of the Invention

[0008] In existing technologies, improvements in heat dissipation of frequency-selective surfaces mostly rely on material replacement or the addition of heat dissipation components. While these solutions can improve thermal conductivity to some extent, they often come with problems such as complex processing, increased costs, and disturbances to electromagnetic performance, making it difficult to balance electromagnetic performance stability and thermal reliability. This invention addresses these shortcomings by solving the following core technical problem: how to reduce the current concentration phenomenon in the edge region of the metal unit under resonant conditions, reduce the power density per unit area, and improve the thermal distribution state from the structure itself, while maintaining the original resonant frequency and frequency selectivity characteristics essentially unchanged, thereby avoiding the formation of local hot spots and the resulting material degradation and performance drift.

[0009] To achieve the above objectives, this invention provides a high-power frequency-selective surface heat dissipation structure and method with a zigzag coupling arm. By introducing a zigzag coupling arm structure around the central metal resonant unit, the edge electric field of the main resonant unit is transferred to the peripheral parasitic structure through near-field coupling, extending the current path and dispersing the current distribution area, thereby macroscopically reducing the local current density peak and Joule heat power density. Through this structural topology optimization, synergistic optimization of electromagnetic and thermal performance is achieved without changing material parameters or increasing system volume and weight.

[0010] The specific technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a high-power frequency selective surface heat dissipation structure with a zigzag coupling arm, comprising a plurality of metal frequency selective units arranged in a periodic array on a metal layer. The metal frequency selection unit is a square region with a side length of 8mm, including a polygonal coupling arm, a metal patch, and an outer metal. The outer metal is a square frame with a width of 0.05mm set around the perimeter of the region, with a square metal patch with a side length of 5mm set at the center. Polygonal coupling arms are set at the four corners of the metal patch, and the distance between the metal patch and the polygonal coupling arms forms an electromagnetic coupling gap. The polygonal coupling arm is formed by connecting two metal line segments end to end to form an L-shaped structure. Its polygonal angle is aligned radially with the corresponding square vertex about the center. The length of each metal line segment is 1.65mm and the width is 0.1mm.

[0011] Preferably, the metal frequency selection unit is arranged in an N×N planar array on the metal layer.

[0012] Preferably, the metal layer is made of electrolytic copper foil with a thickness of 0.05 mm.

[0013] Preferably, the metal frequency selection unit is disposed on the metal layer by a PCB etching process.

[0014] Preferably, the four zigzag coupling arms are symmetrically distributed at 90° with the center of the metal patch as the center of rotational symmetry.

[0015] Preferably, the zigzag coupling arm includes a first line segment and a second line segment; the first line segment extends parallel to the edge of the metal patch, and the second line segment extends vertically outward from the end of the first line segment.

[0016] Preferably, each of the metal frequency selection units is arranged in an array within the metal layer with a period of 8 mm.

[0017] Preferably, the distance between the metal patch and the inner side of the zigzag coupling arm is 0.35 mm.

[0018] In a second aspect, the present invention provides a single-layer or multi-layer transparent wave system utilizing the high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm as described in any of the first aspects.

[0019] Thirdly, the present invention provides a method for operating the single-layer or multi-layer wave-transmitting system described in the second aspect, as follows: When electromagnetic waves are incident perpendicularly or obliquely onto the surface of the heat dissipation structure, surface currents are induced on the metal patch. Especially near the resonant frequency, the current concentrates in the edge region of the metal frequency selection unit, forming a high current density. Due to the electromagnetic coupling gap between the metal patch and the broken-line coupling arm, the edge electric field induces additional current on the broken-line coupling arm through near-field coupling, thus forming multiple current channels. The presence of the broken-line coupling arm extends the equivalent current path and disperses the current originally concentrated at the edge of the metal patch to the peripheral region, reducing the current peak value. Since Joule loss is proportional to the square of the current density, when the current peak value decreases, the local power density decreases significantly, thereby reducing hot spot formation. At the same time, the broken-line coupling arm structure increases the effective distribution area of ​​the metal conductor, which is beneficial for heat diffusion in the plane and makes the temperature distribution more uniform.

[0020] Compared with the prior art, the present invention has the following advantages: (1) The single-layer frequency-selective surface structure unit realizes the topology optimization of the current path, which significantly reduces the intensity of local hot spots. In traditional high-power FSS cells, the induced current is highly concentrated in a narrow region at the edge of the metal cell (such as the edge of a square slot) under resonant conditions, resulting in extremely high local current density peaks and severe concentration of Joule thermal power density. This invention first makes a substantial innovation in the single-layer core structure by introducing parasitic zigzag coupling arms inside the square slot cells. Utilizing near-field electromagnetic coupling, a portion of the electric field energy is successfully transferred to the peripheral parasitic arms.

[0021] This design physically elongates the surface current path and expands the current distribution area, achieving a redistribution and homogenization of the current on the monolayer metal surface. Since Joule loss is proportional to the square of the current density, local power dissipation decreases significantly and nonlinearly as the peak current decreases. Simulations show that the optimized monolayer structure not only significantly reduces the temperature rise but also exhibits a smoother temperature spectrum. Without relying on any external heat dissipation devices, topology optimization alone fundamentally eliminates the risk of localized overheating failure caused by high-power irradiation in monolayer units.

[0022] (2) The single-layer design achieves perfect decoupling of electromagnetic wave transmission and thermal management performance, realizing "zero-sacrifice" optimization. Conventional thermal management methods often inevitably compromise electromagnetic properties, leading to resonant frequency shifts or narrowing of the passband. The single-layer zigzag coupling arm design of this invention possesses high electromagnetic complementarity. Its introduced equivalent reactance primarily functions as an electric field shunt outside the band or at the resonant edge, without destructively affecting the quality factor of the main resonant mode. Therefore, while achieving a significant temperature drop, the optimized single-layer structure maintains extremely high consistency between its transmission coefficient S21 and reflection coefficient S11 within the target operating frequency band and the initial structure, achieving a perfect synergy between electromagnetic transmission and broadband temperature reduction.

[0023] (3) The technical solution has been successfully extended to multi-layer wave-transmitting systems, demonstrating excellent in-band broadband temperature drop robustness. Building upon the significant temperature reduction achieved with a single-layer unit, this invention further successfully reuses and extends this effect to a multi-layer cascaded wave shield system composed of multiple frequency-selective surfaces, a dielectric substrate, and a low-loss dielectric layer. In a multi-layer system, due to multiple reciprocating reflections between layers, strong parasitic cavity resonances are easily formed within a wide passband, leading to a surge in the internal electric field and causing severe volumetric heat generation.

[0024] This invention, by replacing the intermediate layer with an optimized structure featuring a zigzag coupling arm, not only inherits the advantages of single-layer surface hotspot mitigation but also, through impedance matching control of the zigzag arm, disrupts the formation conditions of low-frequency and in-band parasitic standing waves. For example... Figure 9 and Figure 10 As shown, in the extremely wide passband range of 5.2 GHz to 16.6 GHz, the transmission coefficient of the multilayer optimized structure not only did not deteriorate and successfully maintained the high power transmission performance of the cascaded matching, but its steady-state temperature rise curve throughout the entire band was also significantly lower than that of the initial structure, completely eliminating the fatal in-band resonant temperature rise peak in the multilayer cascaded system.

[0025] (4) It significantly improves the structural thermal reliability of the entire system and has extremely high robustness to industrial processing. Whether in a single-layer or multi-layer structure, the technical solution proposed in this invention belongs to the pure structural level of two-dimensional topology optimization, which does not rely on any active heat dissipation device, nor does it require the introduction of high-cost heterogeneous resistive films or lumped components. By reducing the maximum operating temperature and minimizing the temperature gradient, this invention significantly reduces the risk of material aging, delamination, and thermal stress concentration failure caused by local overheating, from single-layer components to multi-layer cascaded systems, and greatly improves the overall continuous operating life of high-power microwave protection and wave transmission systems; moreover, this solution is fully compatible with traditional PCB printed circuits or metal etching processes, and has extremely high manufacturing feasibility and mass production value. Attached Figure Description

[0026] Figure 1This is a structural diagram of a single-layer wave-transmitting system having the high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm according to a preferred embodiment of the present invention; Figure 2 This is a structural diagram of a multilayer wave-transmitting system having the high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm according to a preferred embodiment of the present invention; Figure 3 for Figure 2 Cross-sectional view; Figure 4 for Figure 2 Structural diagram of the top and bottom two-layer patch cell; Figure 5 This is the initial structure used as a control group; Figure 6 This is a structural diagram of a metal frequency selection unit according to a preferred embodiment of the present invention; Figure 7 A single-layer wave-transmitting system having the high-power frequency-selective surface heat dissipation structure of the present invention and a control group initial structure (i.e. Figure 5 A comparison diagram of electromagnetic parameters between single-layer wave-transmitting systems; in the figure, IS represents the initial structure of the control group, and OS represents the optimized structure of the present invention after adding a broken-line coupling arm; Figure 8 A single-layer wave-transmitting system having the high-power frequency-selective surface heat dissipation structure of the present invention and a control group initial structure (i.e. Figure 5 A comparison of the temperature response between single-layer wave-transmitting systems; Figure 9 For a multilayer wave-transparent system having the high-power frequency-selective surface heat dissipation structure of the present invention and having the initial structure of the control group (i.e. Figure 5 A comparison diagram of electromagnetic parameters between multilayer wave-transparent systems; in the figure, MLIS represents the initial structure for comparison, and MLOS represents the optimized structure after adding a broken-line coupling arm; Figure 10 For a multilayer wave-transparent system having the high-power frequency-selective surface heat dissipation structure of the present invention and having the initial structure of the control group (i.e. Figure 5 A comparison of the temperature response between multilayer wave-transmitting systems; The reference numerals in the figure are as follows: dielectric substrate 1; metal layer 2; outer metal frame 2-1; metal patch 2-2; zigzag coupling arm 2-3; outer skin 3-1; patch-type unit 3-2; core layer 3-3; slot-type unit 3-4; inner skin 3-5. Detailed Implementation

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the present invention can be combined accordingly without mutual conflict.

[0028] The present invention provides a high-power frequency selective surface heat dissipation structure with a zigzag coupling arm. The structure mainly includes several metal frequency selective units, which are arranged in a periodic array on the metal layer 2 to form an overall frequency selective surface.

[0029] This invention mainly focuses on optimizing the design of metal layer 2. The optimized FSS structure with zigzag coupling arms designed in this invention is as follows: Figure 6 As shown, a single-group metal frequency selection unit is a square area with a side length of 8mm. Within this square area, there is an outer metal frame 2-1, a metal patch 2-2, and a zigzag coupling arm 2-3. The outer metal frame 2-1 is a square frame circumferentially positioned within the square area, with a width of 0.05mm and an outer side length of 8mm. A square metal patch 2-2 is located at the center of this square frame. The metal patch 2-2 has a side length of 5mm, and zigzag coupling arms 2-3 are located at the four outer corners. The distance between the metal patch 2-2 and the zigzag coupling arms 2-3 forms an electromagnetic coupling gap. Preferably, the distance between the inner sides of the metal patch 2-2 and the zigzag coupling arms 2-3 is 0.35mm.

[0030] In a preferred embodiment of the present invention, the metal frequency selection units should be arranged in an N×N planar array on the metal layer 2. For example, a 40×40 arrangement structure can be adopted, that is, 40 metal frequency selection units are arranged in the horizontal and vertical directions respectively, and adjacent metal frequency selection units are in contact without gaps, so that each metal frequency selection unit is arranged in an array within the metal layer 2 with a period of 8mm.

[0031] In a preferred embodiment of the present invention, the metal layer 2 is made of electrolytic copper foil with a thickness of 0.05 mm. Similarly, the outer metal frame 2-1, the metal patch 2-2, and the zigzag coupling arm 2-3 are also made of electrolytic copper foil with a thickness of 0.05 mm.

[0032] In a preferred embodiment of the present invention, the metal frequency selection unit can be disposed on the metal layer 2 by means of a PCB etching process.

[0033] In this invention, such as Figure 6As shown, the broken line coupling arm 2-3 is formed by connecting two metal line segments end to end to form an L-shaped structure. Its broken line angle is radially aligned with the corresponding square vertex about the center (that is, the broken line angle of the L-shaped structure, the vertex of the square, and the center of the square are collinear). The length of each metal line segment is 1.65mm and the width of each metal line segment is 0.1mm.

[0034] In a preferred embodiment of the present invention, the four zigzag coupling arms 2-3 are symmetrically distributed at 90° with the center of rotational symmetry of the metal patch 2-2 as the center of rotational symmetry. Each zigzag coupling arm 2-3 includes a first line segment and a second line segment. The first line segment extends parallel to the edge of the metal patch 2-2, and the second line segment extends perpendicularly outward from the end of the first line segment.

[0035] Based on the above-mentioned high-power frequency selective surface heat dissipation structure with zigzag coupling arms, the present invention also provides a single-layer or multi-layer wave-transmitting system.

[0036] In the prior art, typical single-layer and multi-layer square slot FSS wave transmission systems have initial structural units as follows: Figure 1 and Figure 2 As shown, a periodic element model is used to model and analyze the electromagnetic-thermal coupling behavior of the frequency-selective surface to study the heat dissipation effect of the structure. The initial structure consists of an outer metal frame 2-1 and a central metal patch 2-2, as shown. Figure 5 As shown. This type of structure forms an equivalent capacitance-inductance network through the metal boundary and the gap region, which can generate a significant resonant response under the action of incident electromagnetic waves. To ensure the relevance of the simulation results, the side length of the outer metal frame 2-1 of the initial structure is set to 8 mm and the width to 0.14 mm, and the side length of the central metal patch 2-2 is set to 5.72 mm, so that the unit can form stable electromagnetic response characteristics in the microwave frequency band (as in the prior art Dong, S., Liang, D., Gao, M. & Pang, X. in 2024 IEEE10th International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications (MAPE) 1-4 (2024).).

[0037] In the aforementioned prior art, the FSS unit is placed within a dielectric substrate 1 with a thickness of 2 mm. This dielectric substrate 1 has a relative permittivity of 4.3 and a loss tangent of 0.025, corresponding to a moderate loss level, and can generate considerable energy dissipation under electromagnetic irradiation conditions. The thermophysical parameters of the dielectric substrate material are selected as follows: density 1800 kg / m³. 3The specific heat capacity is 600 J / (kg•K), and the thermal conductivity is 0.3 W / (m•K), used to describe the heat storage and conduction capabilities during the thermal diffusion process. These parameters together determine the temperature rise characteristics of the structure under electromagnetic loading. The electromagnetic thermal effects of the FSS unit were simulated and analyzed using the multiphysics simulation software COMSOL.

[0038] Specifically, such as Figure 1 The diagram shows a schematic of a single-layer wave-transmitting system. Besides the metal layer 2, the system also includes a dielectric substrate 1, with the substrate 1 positioned on both the upper and lower sides of the metal layer 2. The dielectric substrate can be FR-4 fiberglass epoxy resin board, with a relative permittivity of 4.3, a loss tangent of 0.025, and a thickness of 2.0 mm. Existing metal layer array units generally employ... Figure 5 The configuration shown is different from the one described above, but the present invention adopts the configuration shown above. Figure 6 The configuration shown. (As shown) Figure 5 As shown, the outer metal frame 2-1 has a width of 0.14mm and an outer side length of 8mm. A square metal patch 2-2 is set in the center of this square frame. The side length of the metal patch 2-2 is 5.72mm.

[0039] like Figure 2 The diagram shown is a schematic representation of a multilayer wave-transmitting system. Figure 3 The corresponding cross-sectional view is shown below. To achieve a high-performance frequency response curve, a set of "patch-slot-patch" three-layer cascaded structures was designed as a reference object in multilayer research, based on a typical high-order pole coupling configuration (such as existing technology: Liu Xiaochun, ed. Radar Radome Electrical Performance Design Technology. Beijing: Aviation Industry Press; 2017.). This structure utilizes the mutual coupling between high-order poles to achieve a wider operating bandwidth and excellent passband edge steepness. Among them, the middle slot-type unit 3-4, the metal layer array unit in the existing technology generally adopts, as shown below. Figure 5 The configuration shown is different from the one described above, but the present invention adopts the configuration shown above. Figure 6 The configuration shown; the cascaded quadrilateral patch unit 3-2 adopts the following... Figure 4 The array structure shown has slotted cells 3-4 and patch cells 3-2 embedded in a 0.07mm thick dielectric substrate, with the three FSS screens connected by a dielectric layer. The dielectric layer mainly consists of an outer skin 3-1, an inner skin 3-5, and a core layer 3-3. The inner and outer skins are made of the same material as the dielectric substrate, F4B-2, with a dielectric constant of 2.65 and a loss tangent of 0.001. The core layer, used for support connections, is made of PMI foam. The core layer thickness is 3mm, the outer skin thickness is 0.55mm, and the inner skin thickness is 0.11mm. The incident port power density is set to 25 W / cm². 2 The remaining simulation parameters are the same as those for a single layer.

[0040] Based on the single-layer or multi-layer wave-transmitting system provided by the present invention, the present invention also provides a working method (i.e., working principle), as follows: When electromagnetic waves are incident perpendicularly or obliquely onto the surface of the heat dissipation structure, surface currents are induced on the metal patch 2-2. Especially near the resonant frequency, the current concentrates in the edge region of the metal frequency selection unit, resulting in a high current density. Due to the electromagnetic coupling gap between the metal patch 2-2 and the zigzag coupling arm 2-3, the edge electric field induces additional current in the zigzag coupling arm 2-3 through near-field coupling, thus forming multiple current channels. The presence of the zigzag coupling arm 2-3 extends the equivalent current path and disperses the current originally concentrated at the edge of the metal patch 2-2 to the peripheral region, reducing the current peak value. Since Joule loss is proportional to the square of the current density, as the current peak value decreases, the local power density decreases significantly, thereby reducing hotspot formation. Simultaneously, the zigzag coupling arm 2-3 structure increases the effective distribution area of ​​the metal conductor, which is beneficial for heat diffusion within the plane, resulting in a more uniform temperature distribution.

[0041] In terms of electromagnetic performance, the piecewise linear coupling arm 2-3 participates in coupling as a parasitic structure. However, after matching and designing its length and gap parameters, it does not form a new strong main resonant mode, but rather participates in the main resonant process as an energy distribution path, thereby achieving current redistribution while maintaining a basically stable resonant frequency. By adjusting the piecewise length, linewidth, and gap width of 2-3, the coupling strength can be controlled, allowing the electromagnetic response curve to maintain its original characteristics while simultaneously optimizing thermal performance.

[0042] To verify the technical effectiveness of the heat dissipation structure provided by this invention, the following experiments were conducted: A single-layer transparent wave system with the high-power frequency-selective surface heat dissipation structure of this invention was placed in an electromagnetic-thermal coupling simulation environment. The incident wave was set to a vertically incident plane wave, the operating frequency was 5.3 GHz, and the power density was 3 W / cm². 2 The thermal field was solved under steady-state conditions. Simulation results show that the highest temperature of the control structure without the broken-line coupling arm at the resonant frequency of 5.3 GHz is approximately 136.27 °C, with hot spots concentrated in the edge region of the central patch. The highest temperature of this structure at the resonant frequency is reduced to approximately 105.68 °C, a decrease of about 31 °C. Simultaneously, the resonant frequency drift of the S21 curve is less than 1%, and the transmission characteristics show no significant distortion. These results indicate that the broken-line coupling arm structure effectively disperses the edge current peak, resulting in a more uniform power density distribution, thereby reducing local Joule heating intensity and improving thermal performance.

[0043] Furthermore, this invention also employed the multiphysics simulation software COMSOL to simulate and analyze the electromagnetic thermal effects of the heat dissipation structure. This invention only considers the unidirectional coupling between the electromagnetic field and the thermal field, focusing on the heating effect caused by the electromagnetic field. The simulated technical effect diagrams generated under a single-layer wave-transmitting system are shown below. Figure 7 and Figure 8 As shown.

[0044] like Figure 7 The electromagnetic parameter comparison curves shown indicate that both the optimized and unoptimized structures exhibit significant resonance characteristics within the target frequency band. The S21 curves of both the initial structure (i.e., the structure in the prior art) and the optimized structure of this invention show deep attenuation valleys near the target center frequency, indicating that both structures maintain good frequency selectivity. Comparing the two S21 curves reveals that the resonant frequency position of the optimized structure is essentially the same as that of the initial structure, with only a very small frequency shift. This suggests that the equivalent inductance and capacitance parameters of the main resonant unit did not change significantly after introducing the piecewise linear coupling arm, and the overall electromagnetic filtering function was maintained. Simultaneously, the trend of the S11 curve near the resonance point is similar to that of the initial structure, with no obvious impedance mismatch or additional parasitic resonance peaks, indicating that the structure of this invention improves thermal characteristics without compromising the original electromagnetic response stability. Further observation of the resonance depth reveals that the amplitude of the lowest point of the S21 curve in the optimized structure is essentially on the same order of magnitude as that in the initial structure, with no significant deterioration in transmission or reflection characteristics. This indicates that after the broken-line coupling arm participates in electromagnetic coupling as a parasitic structure, it mainly plays a role in current redistribution and energy dispersion, without forming a new strong main resonant mode or causing a significant decrease in the original resonant quality factor. Therefore, it can be concluded that the present invention achieves structural optimization while maintaining essentially unchanged frequency selectivity performance.

[0045] Figure 8 The figures show a comparison of the temperature response curves of the two structures under the same incident power condition. It is clear from the figures that the temperature rise curve of the optimized structure is generally lower than that of the initial structure. When reaching the steady-state or peak stage, the highest temperature of the optimized structure is significantly lower, and the temperature rise amplitude is significantly reduced. At the same time, the peak value of the temperature distribution curve of the optimized structure is flatter, indicating that the intensity of local hot spots is weakened, and heat is dispersed over a larger area. Combined with electromagnetic field theory analysis, it can be seen that in the initial structure, the current is concentrated in the edge region of the metal unit under resonant state, resulting in a high local current density peak and concentrated Joule thermal power density. In contrast, this invention introduces a piecewise linear coupling arm, allowing some of the electric field energy to be transferred to the peripheral parasitic arm through near-field coupling, effectively extending the current path and expanding the current distribution area, thereby reducing the current density per unit area. Since Joule loss is proportional to the square of the current density, when the current peak value decreases, the local power dissipation decreases nonlinearly, thus significantly suppressing the peak temperature.

[0046] Overall, the optimized structure exhibits a gentler temperature rise slope and a slightly delayed peak time, indicating better thermal buffering and diffusion capabilities under high-power irradiation conditions. This improvement not only reduces the maximum operating temperature but also decreases the temperature gradient, which helps reduce thermal stress concentration and prevents material aging or structural failure caused by localized overheating.

[0047] Combining the two technical effect diagrams, it can be concluded that this invention achieves the following beneficial effects while maintaining the basic stability of the original resonant frequency and frequency selectivity characteristics: without adding additional heat dissipation devices or changing the material system, the broken-line coupling arm structure achieves current dispersion and power density reduction, thereby significantly reducing the peak temperature; it maintains the basic stability of the resonant frequency and frequency selectivity characteristics while improving thermal performance; the structure is simple, easy to manufacture, and suitable for high-power microwave environments; and it improves power tolerance and long-term reliability. The above technical effects all directly stem from the regulation of the current path by the broken-line coupling arm structure, and are inevitable technical results of structural topology optimization, rather than additional effects brought about by material replacement or external heat dissipation devices. Therefore, it can be concluded that this invention, through structural innovation, achieves synergistic optimization between maintaining electromagnetic performance and improving thermal performance, demonstrating significant substantial progress and positive effects.

[0048] For a multilayer wave-transparent system with the high-power frequency-selective surface heat dissipation structure of this invention, the effectiveness of the designed structure in the multilayer wave-transparent system is verified by replacing the frequency-selective surface of the slotted unit in the intermediate layer of the prior art with the frequency-selective surface structure with folded coupling arms designed in this invention. The simulated technical effect diagrams in the multilayer wave-transparent system are as follows. Figure 9 and Figure 10 As shown.

[0049] like Figure 9 As shown in the electromagnetic parameter comparison curves, within the target operating frequency band, the transmission coefficient S21 curve of the optimized structure of this invention almost completely overlaps with that of the initial structure, both exhibiting good bandpass characteristics in the center frequency band, and the insertion loss within the passband does not show significant deterioration. This indicates that in a multi-layer cascaded structure, introducing a carefully designed polygonal coupling arm in the intermediate layer does not disrupt the cascade matching characteristics of the original multi-layer structure, successfully maintaining the high-power transmission performance of the frequency-selective surface.

[0050] To accurately evaluate the thermal safety performance of the structure under high-power irradiation conditions, electromagnetic-thermal multiphysics coupling simulations were performed in the passband frequency band (5.2 GHz to 16.6 GHz) where S21 transmission efficiency is relatively high. Figure 10 shows the comparison curves of the highest steady-state temperature rise as a function of frequency for the initial and optimized structures of the multilayer wave-transparent system under the same incident power.

[0051] from Figure 10 The thermal analysis results clearly show that, across the entire passband from 5.2 GHz to 16.6 GHz, the steady-state temperature rise curve of the optimized structure is significantly lower than that of the initial structure, exhibiting an exceptionally superior broadband temperature reduction effect. During the resonant peak heat generation stage within the passband, the initial structure suffers from severe energy accumulation within the structure due to strong interlayer parasitic resonance and current concentration effects, resulting in a rapid increase in the maximum temperature rise. In contrast, the optimized structure, by introducing a zigzag coupling arm, successfully transfers a portion of the concentrated electric field energy to the peripheral parasitic arm using a near-field coupling mechanism, effectively expanding the surface current distribution area.

[0052] Combining the two technical effect diagrams, it can be concluded that within the entire high-transparency passband (5.2 GHz–16.6 GHz), the electromagnetic performance of the optimized structure designed in this invention is basically consistent with the initial structure, but its maximum operating temperature is significantly suppressed. Not only is the temperature rise greatly reduced, but the peak value of the temperature-frequency change curve is also flatter. This improvement effectively eliminates the risk of material aging, delamination, or failure caused by local overheating when the cascaded FSS structure operates at high power within the band, demonstrating the significant application value of this structural design in high-power microwave protection and electromagnetic-thermal synergistic management.

[0053] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm, characterized in that, It includes several metal frequency selection units arranged in a periodic array on the metal layer (2); The metal frequency selection unit is a square area with a side length of 8mm, including an outer metal frame (2-1), a metal patch (2-2), and a broken line coupling arm (2-3). The outer metal frame (2-1) is a square frame set around the perimeter of the area with a width of 0.05mm. A square metal patch (2-2) with a side length of 5mm is set in the center. Broken line coupling arms (2-3) are set at the four corners of the metal patch (2-2). The distance between the metal patch (2-2) and the broken line coupling arm (2-3) forms an electromagnetic coupling gap. The broken line coupling arm (2-3) is formed by connecting two metal line segments end to end to form an L-shaped structure. Its broken line angle is aligned radially with the corresponding square vertex about the center. The length of the two metal line segments is 1.65mm and the width is 0.1mm.

2. The high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm according to claim 1, characterized in that, The metal frequency selection units are arranged in an N×N planar array on the metal layer (2).

3. The high-power frequency selective surface heat dissipation structure with a zigzag coupling arm according to claim 1, characterized in that, The metal layer (2) is made of electrolytic copper foil with a thickness of 0.05 mm.

4. The high-power frequency selective surface heat dissipation structure with a zigzag coupling arm according to claim 1, characterized in that, The metal frequency selection unit is set on the metal layer (2) by PCB etching process.

5. The high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm according to claim 1, characterized in that, The four zigzag coupling arms (2-3) are symmetrically distributed at 90° with the center of rotational symmetry of the metal patch (2-2).

6. The high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm according to claim 1, characterized in that, The zigzag coupling arm (2-3) includes a first line segment and a second line segment; the first line segment extends parallel to the edge direction of the metal patch (2-2), and the second line segment extends vertically outward from the end of the first line segment.

7. The high-power frequency selective surface heat dissipation structure with a zigzag coupling arm according to claim 1, characterized in that, Each of the metal frequency selection units is arranged in an array within the metal layer (2) with a period of 8 mm.

8. The high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm according to claim 1, characterized in that, The distance between the metal patch (2-2) and the inner side of the zigzag coupling arm (2-3) is 0.35mm.

9. A single-layer or multi-layer transparent wave system utilizing the high-power frequency-selective surface heat dissipation structure with a zigzag coupling arm as described in any one of claims 1 to 8.

10. A method for operating the single-layer or multi-layer wave-transmitting system according to claim 9, characterized in that, Specifically as follows: When electromagnetic waves are incident perpendicularly or obliquely onto the surface of the heat dissipation structure, surface currents are induced on the metal patch (2-2). Especially near the resonant frequency, the current is concentrated in the edge region of the metal frequency selection unit, forming a high current density. Due to the electromagnetic coupling gap between the metal patch (2-2) and the broken-line coupling arm (2-3), the edge electric field induces additional current on the broken-line coupling arm (2-3) through near-field coupling, thus forming multiple current channels. The presence of the broken-line coupling arm (2-3) extends the equivalent current path and disperses the current originally concentrated at the edge of the metal patch (2-2) to the peripheral region, reducing the current peak value. Since Joule loss is proportional to the square of the current density, when the current peak value decreases, the local power density decreases significantly, thereby reducing the formation of hot spots. At the same time, the broken-line coupling arm (2-3) structure increases the effective distribution area of ​​the metal conductor, which is beneficial for heat diffusion in the plane and makes the temperature distribution more uniform.

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