A resistor-loaded regular hexagonal ring ultra-wideband wave absorbing structure

Abstract

The present invention discloses a resistor-loaded regular hexagonal ring ultra-wideband absorbing structure, comprising a plurality of regular hexagonal prism-shaped absorbing units, the absorbing units comprising a surface skin dielectric layer for protecting the inner structure and matching the broadband impedance, an impedance matching dielectric layer for coordinating impedance matching with the surface skin dielectric layer to improve the incident angle stability, an impedance-type frequency selective surface for matching impedance to achieve broadband high-performance absorption, an impedance-type frequency selective surface substrate for promoting bandwidth increase, a dielectric layer for matching with the impedance-type frequency selective surface, interfering and destructively achieving broadband high-performance absorption, and a metal layer for reflecting electromagnetic waves and interfering and destructively with incident electromagnetic waves in the dielectric layer. The present invention adopts the resistor-loaded regular hexagonal ring ultra-wideband absorbing structure of the above structure, which has polarization insensitivity and excellent incident angle stability, and meets outdoor application scenarios to a certain extent.

Description

Technical Field

[0001] The invention relates to an electromagnetic wave absorbing technology, in particular to a resistor-loaded regular hexagonal ring ultra-wideband wave absorbing structure. Background Art

[0002] In the past few years, electromagnetic (EM) absorbing technology has been applied in many fields, such as satellite navigation systems, electromagnetic energy collection, stealth, etc. Among them, the Jaumann absorbing structure is one of the classic absorbing structures proposed since the 1930s. It is a staggered cascade structure of dielectric layers and resistor layers, which can effectively reduce the reflection of electromagnetic waves from conductive surfaces. The Salisbury screen, which is essentially based on a single-layer Jaumann absorbing structure, was patented in 1952.

[0003] Since the above absorbers use the principle of electromagnetic resonance, the key method to expand the absorption band is to increase the number of resonant frequencies by introducing multiple resistance layers. However, the design of multi-layer resistance layers will inevitably lead to an increase in thickness and process complexity. As an extension of the Jaumann absorbing structure, researchers proposed an impedance-type frequency-selective surface absorbing structure - a circuit simulation absorbing structure. The circuit simulation absorbing structure can overcome the limitations of narrow band and excessive thickness through multiple resonances and multi-layer technology, greatly broadening the application prospects of the absorbing structure.

[0004] However, it should be noted that almost all electromagnetic absorbing structures are designed for 10dB absorption. In addition, some of these designs cannot be used in outdoor environments due to their fragile mechanical properties and surface protection measures. In addition, for single-layer absorbers, existing structures are far from reaching the limit of absorption performance. In view of the shortcomings of current electromagnetic absorbing structures, it is necessary to develop high-performance ultra-wideband absorbing structures. Summary of the invention

[0005] The purpose of the present invention is to provide a resistor-loaded regular hexagonal ring ultra-wideband absorbing structure, which has polarization insensitivity and excellent incident angle stability, and meets outdoor application scenarios to a certain extent.

[0006] To achieve the above-mentioned purpose, the present invention provides a resistor-loaded regular hexagonal ring ultra-wideband absorbing structure, comprising a plurality of absorbing units in the form of regular hexagonal prisms, wherein the absorbing units include a surface skin dielectric layer arranged in sequence from top to bottom for protecting an inner structure and matching broadband impedance, an impedance matching dielectric layer for cooperatively matching impedance with the surface skin dielectric layer to improve the stability of the incident angle, an impedance-type frequency selective surface for matching impedance to achieve broadband high-performance absorption, an impedance-type frequency selective surface substrate for promoting bandwidth increase, a dielectric layer for matching with the impedance-type frequency selective surface and causing interference destructively to achieve broadband high-performance absorption, and a metal layer for reflecting electromagnetic waves and causing interference destructively with incident electromagnetic waves in the dielectric layer.

[0007] Preferably, the surface skin dielectric layer is an FR4 board with a relative dielectric constant between 4.2 and 4.5, a thickness between 0.1 and 0.4 mm, and a loss tangent angle of 0.0025.

[0008] Preferably, the relative dielectric constant of the impedance matching dielectric layer is between 1.01 and 1.08, and the thickness is between 2.6 and 3.0 mm.

[0009] Preferably, the impedance type frequency selective surface comprises a plurality of conductive regular hexagonal rings periodically arranged on the impedance type frequency selective surface substrate, and a resistor is arranged at the midpoint of each side of the conductive regular hexagonal ring;

[0010] The conductive regular hexagonal ring is provided with a gap for loading the resistor, and the width of the gap is between 0.1 and 1 mm;

[0011] The distance between two adjacent conductive regular hexagonal rings is between 0.8 and 1.2 mm.

[0012] Preferably, the conductive regular hexagonal ring is made of one of gold, silver and copper;

[0013] The conductive regular hexagonal ring is prepared on the impedance-type frequency selective surface substrate by inkjet printing, electrochemical etching or magnetron sputtering;

[0014] The side length of the conductive regular hexagonal ring is between 4.8 and 5.2 mm, and the width of each side is between 0.9 and 1.1 mm.

[0015] Preferably, the resistor is a lumped chip resistor element or an equivalent resistor obtained by one or more methods of magnetron sputtering, screen printing, and inkjet printing;

[0016] The resistance value of the resistor is between 240 and 280Ω, and the distance between two adjacent resistors is between 0.1 and 1 mm.

[0017] Preferably, the impedance-type frequency selective surface substrate is one of a PI film, a PEN film, a FR4 board, and a F4B board with a thickness between 0.02 and 0.5 mm.

[0018] Preferably, the impedance-type frequency selective surface substrate is an FR4 board with a relative dielectric constant between 4.2 and 4.5, a thickness between 0.1 and 0.4 mm, and a loss tangent of 0.0025.

[0019] Preferably, the relative dielectric constant of the dielectric layer is between 1.01 and 1.08, and the thickness is between 2.6 and 3.0 mm;

[0020] The metal layer is copper foil.

[0021] Preferably, the absorbing unit is formed by vacuum hot pressing of the surface skin dielectric layer, the impedance matching dielectric layer, the impedance type frequency selective surface, the impedance type frequency selective surface substrate, the dielectric layer and the metal layer.

[0022] In the present invention, most of the incident electromagnetic waves generate surface induced currents on the conductive regular hexagonal rings of the impedance-type frequency selective surface, converting electromagnetic energy into heat; after a small part of the incident electromagnetic waves enter the interior of the absorbing unit, the metal layer backplane generates reflections to form reflected waves, which interfere with the incident electromagnetic waves in the dielectric layer and are destructively absorbed.

[0023] Therefore, the present invention has the following characteristics:

[0024] 1. At vertical incidence, the bandwidth with reflectivity lower than -10dB is 4.9GHz-20.3GHz; the bandwidth with reflectivity lower than -20dB is 6.3GHz-19.2GHz.

[0025] 2. It has polarization insensitivity. When electromagnetic waves are incident vertically, the characteristics of TE waves and TM waves are consistent with each other.

[0026] 3. Excellent incident angle stability: Under 50° oblique incidence, the absorber TE wave still shows an absorption rate of more than 90% in the range of 5.9GHz-17.4GHz.

[0027] 4. To a certain extent, it can meet the outdoor application scenarios.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the cross-sectional structure of the present invention.

[0030] Figure 2 It is a schematic diagram of the unit structure of the present invention.

[0031] Figure 3 It is a schematic diagram of the periodic arrangement of the impedance-type frequency selective surface structural units of the present invention.

[0032] Figure 4 The graph is a graph showing the variation of TE wave reflectivity with frequency when the regular hexagonal ring unit of the impedance-type frequency selective surface is loaded with resistors of different resistance values ​​when the electromagnetic wave is incident vertically.

[0033] Figure 5 The present invention is a graph showing the variation of TM wave reflectivity with frequency when the regular hexagonal ring unit of the impedance-type frequency selective surface is loaded with resistors of different resistance values ​​when the electromagnetic wave is incident vertically.

[0034] Figure 6 It is a current distribution diagram on the surface of the wave absorbing structure of the present invention when the resistance of the loading resistor is 260Ω and the frequency point of the electromagnetic wave incident vertically is 6.5GHz.

[0035] Figure 7 It is a current distribution diagram on the surface of the wave absorbing structure of the present invention when the resistance of the loading resistor is 260Ω and the frequency point of the electromagnetic wave incident vertically is 12.5GHz.

[0036] Figure 8 It is a current distribution diagram on the surface of the wave absorbing structure of the present invention when the resistance of the loading resistor is 260Ω and the frequency point of the electromagnetic wave incident vertically is 19GHz.

[0037] Fig. 9 The present invention is a graph showing how the TE wave reflectivity changes with frequency at different incident angles when the resistance of the loading resistor is 260Ω.

[0038] Fig.10 The present invention is a graph showing how the TM wave reflectivity changes with frequency at different incident angles when the resistance of the loading resistor is 260Ω.

[0039] Fig.11 The invention discloses TE wave absorption rates corresponding to different incident angles when the resistance of the loading resistor is 260Ω.

[0040] Fig.12 The invention discloses TM wave absorption rates corresponding to different incident angles when the resistance of the loading resistor is 260Ω.

[0041] Among them: 1. Surface skin dielectric layer; 2. Impedance matching dielectric layer; 3. Impedance type frequency selective surface; 4. Impedance type frequency selective surface substrate; 5. Dielectric layer; 6. Metal layer; 7. Conductive regular hexagonal ring; 8. Resistors. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0043] Figure 1 It is a schematic diagram of the cross-sectional structure of the present invention. Figure 2 It is a schematic diagram of the unit structure of the present invention. Figure 3 It is a schematic diagram of the periodic arrangement of the impedance-type frequency selective surface structural units of the present invention. Figure 4 The graph is a graph showing the variation of TE wave reflectivity with frequency when the regular hexagonal ring unit of the impedance-type frequency selective surface is loaded with resistors of different resistance values ​​when the electromagnetic wave is incident vertically. Figure 5 The present invention is a graph showing the variation of TM wave reflectivity with frequency when the regular hexagonal ring unit of the impedance-type frequency selective surface is loaded with resistors of different resistance values ​​when the electromagnetic wave is incident vertically. Figure 6 It is a current distribution diagram on the surface of the wave absorbing structure of the present invention when the resistance of the loading resistor is 260Ω and the frequency point of the electromagnetic wave incident vertically is 6.5GHz. Figure 7 It is a current distribution diagram on the surface of the wave absorbing structure of the present invention when the resistance of the loading resistor is 260Ω and the frequency point of the electromagnetic wave incident vertically is 12.5GHz. Figure 8 It is a current distribution diagram on the surface of the wave absorbing structure of the present invention when the resistance of the loading resistor is 260Ω and the frequency point of the electromagnetic wave incident vertically is 19GHz. Fig. 9 The present invention is a graph showing how the TE wave reflectivity changes with frequency at different incident angles when the resistance of the loading resistor is 260Ω. Fig.10 The present invention is a graph showing how the TM wave reflectivity changes with frequency at different incident angles when the resistance of the loading resistor is 260Ω. Fig.11 The invention discloses TE wave absorption rates corresponding to different incident angles when the resistance of the loading resistor is 260Ω. Fig.12 The present invention is that when the resistance of the loading resistor is 260Ω, different incident angles correspond to the TM wave absorption rate. Figure 1-Figure 3 As shown, the structure of the present invention includes a plurality of absorbing units in the form of regular hexagonal prisms, wherein the absorbing units include a surface skin dielectric layer arranged in sequence from top to bottom for protecting the inner structure and matching broadband impedance, an impedance matching dielectric layer for coordinating impedance matching with the surface skin dielectric layer to improve the stability of the incident angle, an impedance type frequency selective surface for matching impedance to achieve broadband high-performance absorption, an impedance type frequency selective surface substrate for promoting bandwidth increase, a dielectric layer for matching with the impedance type frequency selective surface and destructively interfering to achieve broadband high-performance absorption, and a metal layer for reflecting electromagnetic waves and destructively interfering with incident electromagnetic waves in the dielectric layer.

[0044] Preferably, the surface skin dielectric layer is an FR4 board with a relative dielectric constant between 4.2 and 4.5, a thickness between 0.1 and 0.4 mm, and a loss tangent angle of 0.0025.

[0045] Preferably, the impedance matching dielectric layer has a relative dielectric constant between 1.01 and 1.08 and a thickness between 2.6 and 3.0 mm. The impedance matching dielectric layer is further made of PMI foam having a relative dielectric constant of 1.05 and a thickness of 2.8 mm.

[0046] Preferably, the impedance type frequency selective surface comprises a plurality of conductive regular hexagonal rings periodically arranged on the impedance type frequency selective surface substrate, the period in the X direction is 16.500 mm, the period in the Y direction is 9.526 mm, and the grid angle between adjacent units is 30°;

[0047] A resistor is arranged at the midpoint of each side of the conductive regular hexagonal ring; a gap for loading the resistor is arranged on the conductive regular hexagonal ring, and the width of the gap is between 0.1 and 1 mm;

[0048] The distance between two adjacent conductive regular hexagonal rings is between 0.8 and 1.2 mm.

[0049] Preferably, the conductive regular hexagonal ring is made of one of gold, silver and copper;

[0050] The conductive regular hexagonal ring is prepared on the impedance-type frequency selective surface substrate by printing, electrochemical corrosion or magnetron sputtering; the side length of the conductive regular hexagonal ring is between 4.8 and 5.2 mm, and the width of each side is between 0.9 and 1.1 mm. Preferably, the resistor is a lumped chip resistor element or an equivalent resistor obtained by one or more methods of magnetron sputtering, screen printing, and printing; the resistance value of the resistor is between 240 and 280 Ω, and the distance between two adjacent resistors is between 0.1 and 1 mm. In this embodiment, a conductive regular hexagonal ring made of metallic silver is deposited on the impedance-type frequency selective surface substrate by magnetron sputtering, with a side length of 5 mm and a width of 1 mm for each side. The spacing between the conductive regular hexagonal rings of two adjacent conductive units is 1 mm, and the resistance value of the resistor in the middle of each side of the conductive regular hexagonal ring is 260 Ω.

[0051] Preferably, the impedance-type frequency selective surface substrate is one of a PI film, a PEN film, a FR4 board, and a F4B board with a thickness between 0.02 and 0.5 mm.

[0052] Preferably, the impedance-type frequency selective surface substrate is a FR4 board with a relative dielectric constant between 4.2-4.5, a thickness between 0.1 and 0.4 mm, and a loss tangent of 0.0025. Furthermore, the impedance-type frequency selective surface substrate is a FR4 board with a relative dielectric constant of 4.3, a thickness of 0.3 mm, and a loss tangent of 0.0025.

[0053] Preferably, the dielectric layer has a relative dielectric constant of 1.01 to 1.08 and a thickness of 2.6 to 3.0 mm; the dielectric layer is a PMI foam with a relative dielectric constant of 1.05 and a thickness of 5.6 mm.

[0054] The metal layer is copper foil with a thickness of 0.035 mm.

[0055] Preferably, the absorbing unit is formed by vacuum hot pressing of the surface skin dielectric layer, the impedance matching dielectric layer, the impedance type frequency selective surface, the impedance type frequency selective surface substrate, the dielectric layer and the metal layer.

[0056] The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure prepared in this embodiment is analyzed using simulation software to explain the working characteristics of the structure.

[0057] like Figure 4 and Figure 5 As shown, when the input resistance fluctuates by ±20Ω, the reflectivity of this embodiment can always be lower than -20dB at 6.5GHz-19GHz. It can be seen that the present invention has good stability.

[0058] A field monitor is set in the simulation software, and the working mechanism of the present invention in the wave absorbing frequency band is analyzed according to its current distribution.

[0059] Embodiment 1, as Figure 6 As shown, at this time, the current at the two resistors in the Y direction is the smallest, the current at the resistors on both sides of the Y direction is moderate, and the current at the vertices of the regular hexagonal rings on both sides of the Y axis is relatively large. Therefore, the electromagnetic energy consumption of the TE wave is mainly absorbed by the interference and destructive effect of the resistors on both sides of the Y direction and the electromagnetic waves that enter the absorbing structure and are reflected back by the metal backplane. At the same time, it can be seen from the TM wave current distribution diagram that the areas with larger currents are in the four vertex areas on both sides of the X-axis of the regular hexagonal ring, followed by the resistors on the sides of the regular hexagonal ring parallel to the X-axis. Therefore, the energy consumption of the part of the electromagnetic energy of the TM wave that is converted into heat energy is different from that of the TM wave.

[0060] Embodiment 2, as Figure 7 As shown, the basic mechanism is consistent with that of the first embodiment, but the current is significantly larger, which means that the impedance matching degree at this frequency point is higher than that of the first embodiment. Under the condition of the same absorbing performance, the percentage of electromagnetic energy converted into heat energy is greater.

[0061] Embodiment three, as Figure 8 As shown, the current distribution is completely different from that of the first and second embodiments. Fig. 9 It can be seen that the current distribution on the conductive regular hexagonal ring is relatively uniform at this time, and the contribution of each resistor to the conversion of electromagnetic energy to thermal energy is not much different.

[0062] Embodiment 4, as Fig. 9 As shown in the figure, the reflectivity changes when the TE wave incident angle changes in this example. When the incident angle is less than 30°, the reflectivity can be kept below -10dB in the range of 5GHz-20GHz; when the incident angle is within the range of 50°, the reflectivity can also be kept below -10dB in the range of 6GHz-17.3GHz; Fig.11 As shown, within the above frequency band, the wave absorption rate of this embodiment is greater than 90%.

[0063] Embodiment 5, as Fig.10 As shown in FIG. 1 , the reflectivity of this example changes when the incident angle of the TM wave changes. When the incident angle is less than 30°, the reflectivity can be kept below -10dB in the range of 6GHz to 20GHz; Fig.12 As shown, within the above frequency band, the wave absorption rate of this embodiment is greater than 90%.

[0064] Therefore, the present invention adopts the above-mentioned resistor-loaded regular hexagonal ring ultra-wideband absorbing structure, which has polarization-insensitive characteristics and excellent incident angle stability, and meets outdoor application scenarios to a certain extent.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A resistor-loaded regular hexagonal ring ultra-wideband absorbing structure, characterized in that: The invention comprises a plurality of wave absorbing units in the form of regular hexagonal prisms, wherein the wave absorbing units comprise a surface skin dielectric layer for protecting an inner structure and matching broadband impedance, an impedance matching dielectric layer for coordinating impedance matching with the surface skin dielectric layer to improve the incident angle stability, an impedance type frequency selective surface for matching impedance to achieve broadband high performance absorption, an impedance type frequency selective surface substrate for promoting bandwidth increase, a dielectric layer for matching with the impedance type frequency selective surface and destructively interfering to achieve broadband high performance absorption, and a metal layer for reflecting electromagnetic waves and destructively interfering with incident electromagnetic waves in the dielectric layer; The impedance type frequency selective surface comprises a plurality of conductive regular hexagonal rings periodically arranged on the impedance type frequency selective surface substrate, and a resistor is arranged at the midpoint of each side of the conductive regular hexagonal ring; The conductive regular hexagonal ring is provided with a gap for loading the resistor, and the width of the gap is between 0.1 and 1 mm; The distance between two adjacent conductive regular hexagonal rings is between 0.8 and 1.2 mm.

2. The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure according to claim 1, characterized in that: The surface skin dielectric layer is an FR4 board with a relative dielectric constant between 4.2 and 4.5, a thickness between 0.1 and 0.4 mm, and a loss tangent angle of 0.0025.

3. The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure according to claim 1, characterized in that: The relative dielectric constant of the impedance matching dielectric layer is between 1.01 and 1.08, and the thickness is between 2.6 and 3.0 mm.

4. The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure according to claim 1, characterized in that: The conductive regular hexagonal ring is made of one of gold, silver and copper; The conductive regular hexagonal ring is prepared on the impedance-type frequency selective surface substrate by inkjet printing, electrochemical etching or magnetron sputtering; The side length of the conductive regular hexagonal ring is between 4.8 and 5.2 mm, and the width of each side is between 0.9 and 1.1 mm.

5. The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure according to claim 1, characterized in that: The resistor is a lumped chip resistor element or an equivalent resistor obtained by one or more methods of magnetron sputtering, screen printing, and inkjet printing; The resistance value of the resistor is between 240 and 280Ω, and the distance between two adjacent resistors is between 0.1 and 1 mm.

6. The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure according to claim 1, characterized in that: The impedance type frequency selective surface substrate is one of a PI film, a PEN film, a FR4 board and a F4B board with a thickness between 0.02 and 0.5 mm.

7. The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure according to claim 1, characterized in that: The impedance type frequency selective surface substrate is an FR4 board with a relative dielectric constant between 4.2 and 4.5, a thickness between 0.1 and 0.4 mm, and a loss tangent angle of 0.0025.

8. The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure according to claim 1, characterized in that: The relative dielectric constant of the dielectric layer is between 1.01 and 1.08, and the thickness is between 2.6 and 3.0 mm; The metal layer is copper foil.

9. The resistor-loaded regular hexagonal ring ultra-wideband absorbing structure according to claim 1, characterized in that: The wave absorbing unit is formed by vacuum hot pressing of the surface skin dielectric layer, the impedance matching dielectric layer, the impedance type frequency selective surface, the impedance type frequency selective surface substrate, the dielectric layer and the metal layer.

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