Low-profile dual-polarization electromagnetic metamaterial absorber with ultra-broadband wave absorption properties

Abstract

The present invention discloses a low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics, including a three-dimensional electromagnetic metamaterial wave absorption structure, a magnetic loss structure and a metal bottom plate; the three-dimensional electromagnetic metamaterial wave absorption structure includes PCB dielectric substrate units arranged in a vertical cross shape; the magnetic loss structure is filled at the lower end of the hollow rectangular parallelepiped structure surrounded by the PCB dielectric substrate units; the metal bottom plate is arranged on the back of the magnetic loss structure; the front of the PCB dielectric substrate unit includes a first lossy U-shaped metal strip and a second lossy U-shaped metal strip cascaded up and down and of different sizes, and the back is plated with a horizontally placed lossy I-shaped metal strip; each metal strip is loaded with a lumped resistor. The electromagnetic performance of the absorber of the present invention is better than most of the existing related designs, and provides a new idea for the design of ultra-wideband electromagnetic absorbers. It has a large and broad application potential in the related designs of electromagnetic stealth and electromagnetic shielding.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-wideband wave-absorbing structures, and in particular relates to a low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave-absorbing characteristics. Background Art

[0002] The core of stealth technology is to reduce the risk of the target being detected by various detection methods. This technology reduces the signal characteristics of the target in multiple frequency bands such as electromagnetic, acoustic, and thermal energy, making it more difficult to be captured by radar, sonar, infrared and other detection systems. In the field of radar stealth, the role of microwave absorbing materials is particularly critical. They can reduce the radar cross-section of equipment by absorbing electromagnetic waves without changing the appearance of the equipment, effectively improving the concealment and battlefield survivability of the equipment. This material has been widely used in aircraft, ships, tanks and other equipment. With the rapid development of information technology, the application of electromagnetic waves has expanded to multiple civil technology fields such as communications, wireless data transmission, and the Internet of Things. Using microwave absorbing materials for electromagnetic compatibility design can reduce electromagnetic interference, improve the sensitivity, stability and safety of equipment, and at the same time reduce electromagnetic radiation, protect information security, and avoid external interference. Therefore, it is particularly important to improve the performance of electromagnetic absorbers, especially those in the low-frequency band of microwaves.

[0003] Traditional absorbing materials, such as magnetic loss materials ferrite and hydroxy iron powder, can provide a wide absorption bandwidth and good low-frequency absorption effect at a small thickness, but they are dense and heavy. Dielectric loss materials, such as silicon carbide and carbon fiber, can obtain good absorption effect by increasing the number of layers and thickness, but the preparation process is complicated and the thickness is large. In recent years, electromagnetic metamaterial technology has made significant progress. Microstructure materials based on artificial design have attracted widespread attention due to their unique electromagnetic properties, providing new possibilities for the research and design of absorbing materials. Compared with traditional absorbing materials, electromagnetic metamaterial absorbers have the advantages of flexible design, adjustable electromagnetic parameters, wide absorption bandwidth, small size, thin thickness, and light weight. They have great application potential in the fields of electromagnetic stealth and electromagnetic compatibility. At present, there are still deficiencies in the research on electromagnetic metamaterial absorbers in the microwave frequency band. Broadband electromagnetic metamaterial absorbers widely used in the field of electromagnetic compatibility usually have problems such as complex structure, large thickness, and poor low-frequency performance. Therefore, it is of great research value and significance to design electromagnetic absorbers with both low-frequency and broadband characteristics.

[0004] From the perspective of the unit structure design of electromagnetic metamaterial absorbers, their unit structures can be divided into two-dimensional and three-dimensional structures. The two-dimensional structure achieves broadband absorption by designing a periodic unit structure on a two-dimensional plane. The structural design usually uses a resonator or an electromagnetic band gap structure (EBG) to enhance the absorption effect. It consists of periodically arranged conductive patterns, which are usually printed on a dielectric substrate. By designing the shape, size and arrangement of the pattern, efficient absorption of electromagnetic waves can be achieved within a specific frequency band. However, the existing electromagnetic metamaterial two-dimensional absorber designs are mostly faced with the problems of insufficient absorption bandwidth, high difficulty in designing low-frequency absorption below 2GHz, large structural cross-section, and limited performance. Due to the increase in the spatial design dimension, the unit structure flexibility of the three-dimensional electromagnetic metamaterial absorber is significantly higher than that of the two-dimensional electromagnetic metamaterial absorber. Compared with the two-dimensional electromagnetic metamaterial absorber, the three-dimensional electromagnetic metamaterial absorber can achieve a wider absorption band and better absorption performance stability under oblique incidence of electromagnetic waves. However, the design difficulty of achieving low-frequency absorption below 1GHz is still large, and the structural cross-section is large, the design structure is complex, and the manufacturing cost is increased. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics in view of the deficiencies of the above-mentioned prior art. By combining a three-dimensional electromagnetic metamaterial wave absorption structure loaded with a lumped resistor and a magnetic loss structure, the inherent wave absorption band of the magnetic loss structure is greatly broadened, and ultra-wideband high-efficiency wave absorption characteristics from the UHF band to the K band are achieved. The relative absorption bandwidth reaches 187.2%, which is better than most existing electromagnetic absorber designs, and solves the problem that conventional two-dimensional or three-dimensional electromagnetic absorbers have poor low-frequency absorption effect and insufficient absorption band, and have broad application prospects in the fields of electromagnetic stealth and electromagnetic shielding.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] A low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics comprises a three-dimensional electromagnetic metamaterial wave absorption structure, a magnetic loss structure and a metal bottom plate; the three-dimensional electromagnetic metamaterial wave absorption structure comprises PCB dielectric substrate units arranged in a vertical cross shape; the magnetic loss structure is filled in the lower end of a hollow rectangular parallelepiped structure surrounded by PCB dielectric substrate units in the three-dimensional electromagnetic metamaterial wave absorption structure, and is arranged periodically; the metal bottom plate is arranged on the back of the magnetic loss structure to reflect incident electromagnetic waves and enhance the absorption effect of electromagnetic waves; the front of the PCB dielectric substrate unit comprises a first lossy U-shaped metal strip and a second lossy U-shaped metal strip that are cascaded up and down and have different sizes, and the back is plated with a horizontally placed lossy I-shaped metal strip; the first lossy U-shaped metal strip, the second lossy U-shaped metal strip and the lossy I-shaped metal strip are all loaded with lumped resistance.

[0008] To optimize the above technical solutions, the specific measures taken also include:

[0009] The first lossy U-shaped metal strip and the second lossy U-shaped metal strip are respectively arranged above and below the front side of the PCB dielectric substrate unit; both arms of the first lossy U-shaped metal strip and the second lossy U-shaped metal strip extend downward.

[0010] The length and width of the two arms of the second lossy U-shaped metal strip are greater than the length and width of the two arms of the first lossy U-shaped metal strip.

[0011] The first lossy U-shaped metal strip is loaded with two lumped resistors, which are respectively welded on both sides of the first lossy U-shaped metal strip; a lumped resistor is loaded in the middle of the second lossy U-shaped metal strip; and a lumped resistor is loaded in the middle of the lossy I-shaped metal strip.

[0012] The two arms of the first lossy U-shaped metal strip and the second lossy U-shaped metal strip in each of the above-mentioned PCB dielectric substrate units respectively form a cascaded first transmission line structure and a second transmission line structure with the two arms of the first lossy U-shaped metal strip and the second lossy U-shaped metal strip in another adjacent PCB dielectric substrate unit; the incident port impedance of the cascaded first transmission line structure and the second transmission line structure is capacitive in the low-frequency domain.

[0013] The magnetic loss structure mentioned above is Eccosorb TM The square unit structure of the FGM-125 magnetic loss absorber.

[0014] The length and width of the metal base plate are consistent with the length and width of the three-dimensional electromagnetic metamaterial absorbing structure.

[0015] When an electromagnetic wave is incident on the electromagnetic absorber, the three-dimensional electromagnetic metamaterial absorbing structure and the magnetic loss structure complement each other, wherein the magnetic loss structure realizes efficient absorption of electromagnetic waves in the C-band and the X-band, and the first lossy U-shaped metal strip and the second lossy U-shaped metal strip in the three-dimensional electromagnetic metamaterial absorbing structure realize efficient absorption in the UHF to C bands, and at the same time, the first lossy U-shaped metal strip, the second lossy U-shaped metal strip and the lossy I-shaped metal strip realize efficient absorption in the X to K bands.

[0016] The present invention has the following beneficial effects:

[0017] The present invention absorbs incident electromagnetic waves by combining a three-dimensional electromagnetic metamaterial structure loaded with lumped resistors, a magnetic loss structure and a metal bottom plate, and provides a low-profile dual-polarization electromagnetic metamaterial absorber design with ultra-wideband wave absorption characteristics, thereby achieving absorption in the low-frequency UHF band, with the lowest absorption frequency reaching 0.737 GHz, a wide absorption frequency band covering from the UHF band to the K band, a high absorption rate, and an in-band absorption rate of more than 90%.

[0018] The present invention realizes dual polarization and angle insensitivity: through the combined design of three-dimensional electromagnetic metamaterial structure, magnetic loss structure and metal bottom plate, its ultra-wide wave absorption characteristics can be guaranteed under large angle incidence, and the centrally symmetrical unit structure makes the absorption performance of the ultra-wideband electromagnetic absorber insensitive to the polarization mode of the incident wave, realizing a new ultra-wideband electromagnetic absorber structure design that absorbs from UHF band to K band. By introducing the magnetic loss structure in the unit structure, the ultra-wideband electromagnetic absorber realizes dual polarization absorption, and the frequency band range of absorption rate>90% is 0.737 to 22.247GHz, and the relative bandwidth reaches 187.2%, which is better than most existing electromagnetic absorber structures.

[0019] The specific low-profile structural characteristics of the present invention are as follows: the ultra-wideband electromagnetic absorber structure has a lower profile than the conventional electromagnetic absorber structure, and its cross-sectional thickness is only 0.0489 of the wavelength corresponding to the lowest absorption frequency.

[0020] The invention has a simple structural design, low processing difficulty and low processing cost. The electromagnetic performance of the low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorbing characteristics is better than most of the existing related designs, which provides a new idea for the design of ultra-wideband electromagnetic absorbers. It has great and broad application potential in the related designs of electromagnetic stealth and electromagnetic shielding. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a three-dimensional schematic diagram of the ultra-wideband electromagnetic absorber of the present invention;

[0022] Figure 2 This is a front structural diagram of a three-dimensional electromagnetic metamaterial unit of the present invention;

[0023] Figure 3 It is a back structural diagram of the three-dimensional electromagnetic metamaterial unit of the present invention;

[0024] Figure 4 It is a structural diagram of the magnetic loss structure and the metal bottom plate of the present invention;

[0025] Figure 5 TE and TM waves are reflection coefficient and absorptivity curves under normal incidence of the present invention;

[0026] Figure 6is the TE wave oblique incidence absorptivity curve of the present invention;

[0027] Figure 7 This is the TM wave oblique incidence absorptivity curve of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Although the steps in the present invention are arranged with numbers, they are not used to limit the order of the steps. Unless the order of the steps is clearly stated or the execution of a certain step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" used in this article involves and covers any and all possible combinations of one or more of the associated listed items.

[0030] like Figure 1-4 As shown, a low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics includes a three-dimensional electromagnetic metamaterial wave absorption structure loaded with a lumped resistor, a magnetic loss structure and a metal bottom plate;

[0031] The three-dimensional electromagnetic metamaterial absorbing structure comprises a PCB dielectric substrate arranged in a vertical cross shape, wherein the front side of the dielectric substrate unit comprises two lossy U-shaped metal strips (i.e., a first lossy U-shaped metal strip and a second lossy U-shaped metal strip) cascaded up and down and of different sizes, and the back side is plated with a lossy I-shaped metal strip placed horizontally, thereby achieving absorption in the X to K bands;

[0032] The magnetic loss structure is Eccosorb TM The FGM-125 magnetic loss absorber has a square unit structure; the metal base plate reflects the incident electromagnetic waves to enhance the absorption effect of the electromagnetic waves; and the design combines the magnetic loss structure and the metal base plate to achieve ultra-wideband absorption from the UHF band to the K band, with an absorption range of 0.737 GHz to 22.247 GHz.

[0033] The three-dimensional electromagnetic metamaterial absorbing structure, the magnetic loss material and the metal bottom plate work together to form an ultra-wideband absorption performance.

[0034] In the embodiment, the length and width of the two arms of the lower U-shaped metal strip on the front side wall of the three-dimensional electromagnetic metamaterial absorbing unit are greater than the upper cascaded U-shaped metal strip, wherein the upper U-shaped metal strip is loaded with two lumped resistors, and the lower U-shaped metal strip is loaded with a lumped resistor in the middle. The two arms of the two U-shaped metal strips and the two arms of the laterally adjacent U-shaped metal strips together constitute a transmission line structure. Through size optimization, the incident port impedance of the two cascaded transmission line structures is capacitive in the low-frequency domain. The back side wall of the three-dimensional electromagnetic metamaterial absorbing unit is plated with a lossy I-shaped metal strip placed laterally, and a lumped resistor is loaded in the middle of the I-shaped metal strip.

[0035] In the embodiment, the magnetic loss structure unit is filled at the lower end of the hollow area of ​​the three-dimensional electromagnetic metamaterial absorbing structure unit and is arranged periodically. A metal base plate is adhered to the back of the magnetic loss structure, and the length and width of the metal base plate are consistent with the length and width of the three-dimensional electromagnetic metamaterial absorbing structure.

[0036] In the embodiment, when an electromagnetic wave is incident on the electromagnetic absorber, the three-dimensional electromagnetic metamaterial absorbing structure and the magnetic loss structure complement each other, wherein the magnetic loss structure realizes efficient absorption of electromagnetic waves in the C-band and the X-band, and the lossy U-shaped metal strip in the three-dimensional electromagnetic metamaterial absorbing structure that is capacitive in the low frequency band enables the overall structure to realize efficient absorption in the UHF to C bands, and the cascade design of the three lossy metal strips also realizes efficient absorption in the X to K bands.

[0037] The low-frequency absorption band is formed by the combined effect of the U-shaped metal strip on the front side wall of the three-dimensional electromagnetic metamaterial absorbing structure and the magnetic loss structure; within the absorption band, the magnetic loss structure achieves high-efficiency absorption of incident electromagnetic waves in the low-frequency band, while the lossy U-shaped metal strip exhibits capacitive properties in the low-frequency band, broadening the absorption bandwidth of the low-frequency band and making the lowest absorption frequency reach 0.737 GHz.

[0038] The high-frequency absorption band is realized by the cascade of three lossy metal strips in the three-dimensional electromagnetic metamaterial absorbing structure; within the absorption band, the metal strips loaded with lumped resistance in the three-dimensional electromagnetic metamaterial absorbing structure form LC series resonance, realizing high-efficiency absorption of incident electromagnetic waves in the high-frequency band, and the energy of the incident electromagnetic waves is lost by the lumped resistance.

[0039] For details, see Figure 1 , Figure 1The figure shows a 2*2 unit schematic diagram of a low-profile dual-polarization electromagnetic metamaterial absorber structure with ultra-wideband wave absorption characteristics of the present invention. The structure as a whole is composed of a three-dimensional electromagnetic metamaterial structure, a magnetic loss structure and a metal base plate. The three-dimensional electromagnetic metamaterial structure is placed directly above the metal base plate. The three-dimensional electromagnetic metamaterial structure is a periodic structure arranged in a vertical cross shape. Each wave absorbing structure unit is composed of a hollow rectangular structure surrounded by four FR-4 dielectric substrates with a thickness of 0.254mm and a dielectric constant of 4.3. The wave absorbing structure height h is 19.9mm and the period p is 12mm.

[0040] Figure 2 The front structure diagram of the three-dimensional electromagnetic metamaterial unit of the present invention is shown. The front unit structure consists of two U-shaped metal strips 1 and 2 cascaded up and down (representing the first lossy U-shaped metal strip and the second lossy U-shaped metal strip, respectively).

[0041] The distance between the U-shaped metal strip 1 and the top of the dielectric substrate is 0.1 mm. The width of the U-shaped metal strip 1 is w1 = 0.2 mm, and the horizontal length is l1 = 11.35 mm. The length of both sides of the U-shaped metal strip 1 extending in the -z direction is l2 = 6 mm. The width of the extended metal strip is w2 = 0.1 mm. The width of all lumped resistors is 0.8 mm. Two lumped resistors 1 (350 Ω) with the same resistance are respectively welded on both sides of the U-shaped metal strip 1, and the distance between the two lumped resistors is l3 = 6.8 mm.

[0042] The U-shaped metal strip 2 is located below the U-shaped metal strip 1 at a distance of g1=2.7mm. The width of the U-shaped metal strip 2 is w3=0.1mm, and the horizontal length is l4=10.15mm. The length of both sides of the U-shaped metal strip 2 extending in the -z direction is l5=11mm, and the width of the extended metal strip is w4=0.7mm. The lumped resistor 2 is welded at its center position (300Ω).

[0043] Figure 3 The figure shows the back structure of the three-dimensional electromagnetic metamaterial unit of the present invention. The back unit structure is composed of an I-type metal strip. The height of the I-type metal strip from the metal base plate is h1=15.2mm, the width of the I-type metal strip is w5=0.2mm, the horizontal length is l6=11.55mm, and the lumped resistor 3 is welded at its center position (400Ω).

[0044] Figure 4 This is a schematic diagram of the magnetic loss structure and the metal base plate. The length and width of the metal base plate are both 12 mm. The magnetic loss structure is directly placed on the metal base plate. The magnetic loss structure is Eccosorb TMThe square unit structure of the FGM-125 magnetic loss absorber has a length and width of p1 = 11.3 mm, an overall height of t1 = 6.6 mm, and a distance from the side with the dielectric substrate of g2 = 0.223 mm.

[0045] Figure 5 The figure shows the reflection coefficient and absorptivity curves of TE and TM waves under normal incidence in the embodiment of the present invention. Figure 5 It can be seen that the present invention has an ultra-wide absorption band, the TE and TM wave curves are almost overlapped, and it has a dual-polarization absorption effect. It exhibits low reflection characteristics (S11<-10dB) in the frequency range of 0.737GHz to 22.247GHz, the absorption rate is above 90%, and the relative bandwidth reaches 187.2%.

[0046] Figure 6 The figure shows the simulation curve of the TE wave oblique incidence absorptivity in the embodiment of the present invention. Figure 6 It can be seen that when the TE wave is obliquely incident, the absorption rate of the present invention can be maintained at more than 90% within the frequency band within an incident angle of 20 degrees. When the incident angle is 30 and 40 degrees, the absorption rate of most frequency points in the frequency band can be maintained at more than 80%, and the absorption rate decreases only around 17 GHz.

[0047] Figure 7 The figure shows the simulation curve of the TM wave oblique incidence absorptivity in the embodiment of the present invention. Figure 7 It can be seen from the figure that under the condition of oblique incidence of TM wave, within 40 degrees of oblique incidence, the absorption rate of most frequency points in the frequency band can be maintained above 90%.

[0048] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0049] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics, characterized in that: The invention comprises a three-dimensional electromagnetic metamaterial absorbing structure, a magnetic loss structure and a metal bottom plate; the three-dimensional electromagnetic metamaterial absorbing structure comprises PCB dielectric substrate units arranged in a vertical cross shape; the magnetic loss structure is filled in the lower end of the hollow rectangular parallelepiped structure surrounded by the PCB dielectric substrate units in the three-dimensional electromagnetic metamaterial absorbing structure, and is arranged periodically; the metal bottom plate is arranged on the back of the magnetic loss structure to reflect the incident electromagnetic wave and enhance the absorption effect of the electromagnetic wave; the front of the PCB dielectric substrate unit comprises a first lossy U-shaped metal strip and a second lossy U-shaped metal strip cascaded up and down and having different sizes, and the back is plated with a horizontally placed lossy I-shaped metal strip; the first lossy U-shaped metal strip is loaded with two lumped resistors, which are respectively welded on both sides of the first lossy U-shaped metal strip; a lumped resistor is loaded in the middle of the second lossy U-shaped metal strip; and a lumped resistor is loaded in the middle of the lossy I-shaped metal strip.

2. A low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics according to claim 1, characterized in that: The first lossy U-shaped metal strip and the second lossy U-shaped metal strip are respectively arranged above and below the front side of the PCB dielectric substrate unit; both arms of the first lossy U-shaped metal strip and the second lossy U-shaped metal strip extend downward.

3. The low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics according to claim 2, characterized in that: The length and width of the two arms of the second lossy U-shaped metal strip are greater than the length and width of the two arms of the first lossy U-shaped metal strip.

4. The low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics according to claim 1, characterized in that: The two arms of the first lossy U-shaped metal strip and the second lossy U-shaped metal strip in each PCB dielectric substrate unit respectively form a cascaded first transmission line structure and a second transmission line structure with the two arms of the first lossy U-shaped metal strip and the second lossy U-shaped metal strip in another adjacent PCB dielectric substrate unit; the incident port impedance of the cascaded first transmission line structure and the second transmission line structure is capacitive in the low frequency domain.

5. The low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics according to claim 1, characterized in that: The magnetic loss structure is Eccosorb TM The square unit structure of the FGM-125 magnetic loss absorber.

6. The low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics according to claim 1, characterized in that: The length and width of the metal base plate are consistent with the length and width of the three-dimensional electromagnetic metamaterial absorbing structure.

7. The low-profile dual-polarization electromagnetic metamaterial absorber with ultra-wideband wave absorption characteristics according to claim 1, characterized in that: When electromagnetic waves are incident on the electromagnetic metamaterial absorber, the three-dimensional electromagnetic metamaterial absorbing structure and the magnetic loss structure complement each other, wherein the magnetic loss structure realizes efficient absorption of electromagnetic waves in the C-band and the X-band, and the first lossy U-shaped metal strip and the second lossy U-shaped metal strip in the three-dimensional electromagnetic metamaterial absorbing structure realize efficient absorption in the UHF to C-band, and at the same time, the first lossy U-shaped metal strip, the second lossy U-shaped metal strip and the lossy I-shaped metal strip realize efficient absorption in the X to K-band.

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