A wideband bandwidth metamaterial absorber covering L, S, C, X, and Ku bands

Abstract

This invention discloses a wide-bandwidth, wide-angle metamaterial microwave absorber covering the L, S, C, X, and Ku bands, belonging to the field of stealth technology. The unit structure of the microwave absorber includes an upper FR4 plate with three-dimensional printed high-resistivity carbon paste, a middle paper honeycomb support layer, and a bottom magnetic material attached to a metal plate. The upper FR4 plate provides microwave absorption performance at mid and high frequencies, while the bottom magnetic material provides microwave absorption performance at low frequencies. The two are fixed by the paper honeycomb of the middle support layer. By combining a three-dimensional microwave absorber with magnetic materials, this invention achieves wide-bandwidth, wide-angle microwave absorption performance. The composite microwave absorber structure constructed by this invention has high structural strength and achieves lightweight design.

Description

Technical Field

[0001] This invention belongs to the field of stealth technology, specifically relating to a wide-bandwidth, wide-angle metamaterial absorber covering the L, S, C, X, and Ku bands. Background Technology

[0002] With the continuous improvement of weapon and equipment performance in modern warfare, stealth has become an increasingly important indicator. Depending on the type of detector, stealth technology can be divided into radar stealth, infrared stealth, and visible light stealth. Among these, radar stealth, which effectively reduces the radar cross-section (RCS) of an object, is the most crucial requirement in the stealth field. Radar stealth technology can be broadly divided into shape design and radar-absorbing materials. Early methods reduced the RCS by rationally designing the shape of the object being detected, primarily by reflecting electromagnetic waves in the detection direction to other directions; however, this method often had limited stealth capabilities. Radar-absorbing materials, on the other hand, dissipate energy as heat, exhibiting outstanding performance in ultra-wideband and wide-angle applications.

[0003] In recent years, metamaterials have been widely used in the field of electromagnetic stealth due to their unique ability to absorb electromagnetic waves. Traditional electromagnetic absorbers, such as Salisbury screens and Jaumann absorbers, generally suffer from narrow absorption bandwidth and high mass density. By introducing lumped elements into metallic structures, ohmic losses or adjustable functions can be achieved, thereby broadening the absorption bandwidth.

[0004] The stacking of two-dimensional multilayer structures can often achieve a wide bandwidth by bringing the resonant frequencies close together; however, these absorbers are often heavy, limiting their application scenarios. To overcome weight limitations on certain aircraft surfaces, it is necessary to simultaneously achieve lightweight, high structural strength, and wide bandwidth. Honeycomb composite absorbers, with their natural polygonal honeycomb structure, can provide strong structural support while maintaining ultra-light weight. Doping paper honeycomb with carbon fibers as the absorption loss structure and then printing silver paste in a stepped manner to improve impedance matching can also achieve broadband absorption. Mounting loss structures on three-dimensional dielectric substrates and designing thin and light absorbers using metal resonance or the resonance of the structure itself has become a common method. However, it is difficult for simple two-dimensional or three-dimensional structures to extend the absorption bandwidth below 1 GHz, which is one of the current challenges faced by metamaterial absorbers. Summary of the Invention

[0005] This invention provides a wide bandwidth and angle metamaterial absorber covering the L, S, C, X, and Ku bands. By utilizing the absorption characteristics of magnetic materials at low frequencies, the operating frequency band of the absorber is extended to 0.84 GHz. Compared with traditional designs, the absorber of this invention has a larger bandwidth and better angle stability, and is also lightweight and has high structural strength.

[0006] To achieve the above objectives, the present invention adopts the above technical solution:

[0007] A wideband bandwidth metamaterial microwave absorber covering L, S, C, X, and Ku bands is obtained by periodically arranging unit structures, wherein the unit structure includes: an upper FR4 plate with three-dimensional printed high-resistivity carbon paste, a middle paper honeycomb support layer, and a bottom magnetic material attached to a metal plate.

[0008] The upper FR4 board has a cross-shaped cross structure; the paper honeycomb of the middle support layer is used to fix and connect the upper FR4 board and the bottom magnetic material, thus constructing a composite wave-absorbing structure with high structural strength and lightweight.

[0009] A composite absorber of electromagnetic metamaterials and magnetic materials is obtained by periodically arranging the unit structure horizontally and vertically. Broadband absorption is achieved by printing high-resistivity carbon paste on the upper FR4 plate. Two slots are cut out of the high-resistivity carbon paste to improve the absorption performance. At low frequencies, the upper structure has a certain degree of wave transmission. The electric field is mainly concentrated at the cross-shaped vertical slots of the high-resistivity carbon paste, generating strong resonance. The absorption characteristics are achieved through resonance loss. As the frequency increases, the resonance effect gradually weakens, but multiple standing waves are gradually generated. The resonance absorption becomes weaker and weaker while the standing wave loss becomes stronger and stronger. The two complement each other dynamically over a wide frequency band. By cutting a vertical slot in each of the two FR4 plates and splicing them together, the two FR4 plates intersect each other perpendicularly to achieve dual polarization characteristics.

[0010] The underlying magnetic material is soft, thin, and easy to bond with shielding objects. It can adapt to low and high temperature environments and maintain stable performance over a wide temperature range. It has a large dielectric constant and magnetic permeability at low frequencies, exhibiting a certain degree of wave absorption, which is beneficial for widening the low-frequency bandwidth of the three-dimensional wave absorber and plays a dominant role in the composite wave absorbing structure. As the frequency increases, the electric field strength on the surface of the magnetic material gradually weakens, and the wave absorption effect is mainly achieved by the upper three-dimensional printed high-resistivity carbon paste FR4 plate.

[0011] Beneficial effects: This invention provides a wide-bandwidth, wide-angle metamaterial absorber covering the L, S, C, X, and Ku bands, which has the following advantages compared with existing technologies:

[0012] (1) This invention provides a composite wide bandwidth metamaterial wave absorber by combining electromagnetic metamaterials and magnetic materials; compared with traditional two-dimensional and three-dimensional metamaterial wave absorbers, this invention has a novel structure, is highly innovative and has high structural strength.

[0013] (2) This invention has ultra-wideband operating characteristics. By designing a metamaterial absorber with a high-resistivity surface, the operating frequency band covers the S, C, X, and Ku bands. By adding magnetic material to the bottom of the structure, the overall absorption bandwidth can be extended to below the L band. In the range of 0.84~20GHz, the metamaterial absorber can absorb more than 90% of the vertical incident wave energy, with a relative bandwidth of 183.9%.

[0014] (3) The present invention has wide bandwidth and wide angle absorption performance for both TE and TM polarized electromagnetic waves, and under TM polarization conditions, the angle stability can reach 60°.

[0015] (4) By using magnetic materials, this invention reduces the overall height and mass of the absorber. The overall height of the absorber is only 26.5 mm, and the surface density is only 0.74 g / cm³. 2 This makes it of significant value in radar stealth for military targets. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a single unit of a wide bandwidth metamaterial absorber covering the L, S, C, X, and Ku bands in an embodiment of the present invention.

[0017] Figure 2 This is a graph showing the reflectivity and absorptivity of a wide-bandwidth metamaterial absorber covering the L, S, C, X, and Ku bands in an embodiment of the present invention.

[0018] Figure 3 This is an angular stability curve of a wide-bandwidth, wide-angle metamaterial absorber covering the L, S, C, X, and Ku bands under TE polarization in an embodiment of the present invention.

[0019] Figure 4 This is an angular stability curve of a wide-bandwidth, wide-angle metamaterial absorber covering the L, S, C, X, and Ku bands under TM polarization in an embodiment of the present invention.

[0020] Figure 5 This is a structural diagram of a wide-bandwidth, wide-angle metamaterial absorber covering the L, S, C, X, and Ku bands in an embodiment of the present invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 5 As shown, a wideband bandwidth metamaterial absorber covering the L, S, C, X, and Ku bands is obtained by arranging unit structures in a horizontal and vertical periodic pattern, as shown in the figure. Figure 1As shown, the unit structure, from top to bottom, consists of an upper FR4 board made of three-dimensional printed high-resistivity carbon paste, a middle support layer of paper honeycomb, and a bottom layer of magnetic material attached to a metal plate. The upper FR4 board has a cross-shaped structure. Two slots are cut out of the high-resistivity carbon paste to improve the wave absorption performance. The position and size of the slots are optimized using simulation software to achieve the best wave absorption effect. The middle support layer of paper honeycomb is used to fix and connect the upper FR4 board and the bottom magnetic material, thus constructing a composite wave absorption structure with high structural strength and lightweight design. The bottom magnetic material of the unit structure has a length and width p of 12mm and a thickness h0 of 1.05mm; the paper honeycomb of the middle support layer has a length and width p of 12mm and a thickness h1 of 5.45mm; the upper FR4 board with three-dimensional printed high-resistivity carbon paste has a thickness t of 0.3mm, a slot width n of 1mm, a lower high-resistivity carbon paste height h2 of 13mm, a middle high-resistivity carbon paste height h3 of 2mm, an upper high-resistivity carbon paste height h4 of 3mm, and an overall FR4 height of 20mm; the overall height of the absorber is 26.5mm. The parameters of each part were optimized using simulation software to ensure optimal absorption characteristics.

[0023] like Figure 2 The figure shows the electromagnetic parameter curves of the designed absorber, with an absorption frequency range of 0.84~20GHz. The reflection coefficients under TE-polarized and TM-polarized wave incidence are shown below. Figure 3 and Figure 4 As shown, the angular stability can reach 30° under TE polarization; while under TM wave oblique incidence, the composite metamaterial absorber has excellent stealth effect within a wide angle range of 60°.

[0024] The structure of the frequency selective surface in this invention is not limited to this. The upper absorber can be replaced with other forms of three-dimensional absorbers according to actual needs, as long as its size is consistent with the magnetic material of the lower layer. The dielectric substrate can be low-loss Rogers 5880 or a low relative permittivity dielectric. Magnetic materials with different electromagnetic properties can be selected according to specific needs, as long as the electromagnetic loss of the material is high enough and the relative permittivity and thickness meet good impedance matching requirements.

[0025] The above description is merely a preferred embodiment of the present invention. To facilitate understanding and application of the present invention by those skilled in the art, it is evident that various modifications can be easily made, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the embodiments described herein. Any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A wideband bandwidth metamaterial absorber covering L, S, C, X, and Ku bands, characterized in that, The absorber is formed by arranging unit structures in a horizontal and vertical periodic manner. The unit structure consists of a three-dimensional electromagnetic material layer, a support layer, and a magnetic material layer from top to bottom. The surface of the three-dimensional electromagnetic material layer is printed with high-resistivity carbon paste. The three-dimensional electromagnetic material layer is an FR4 board with a cross-shaped structure. Two parallel slots are provided on the high-resistivity carbon paste to achieve a vertical cross combination in two dimensions. The bottom of the magnetic material layer is attached to a metal plate.

2. The wideband bandwidth metamaterial absorber covering L, S, C, X, and Ku bands according to claim 1, characterized in that, The support layer is a paper honeycomb structure.

3. The wideband bandwidth metamaterial absorber covering L, S, C, X, and Ku bands according to claim 1, characterized in that, The three-dimensional electromagnetic material layer has a thickness of 0.3 mm and a height of 20 mm.

4. The wideband bandwidth metamaterial absorber covering L, S, C, X, and Ku bands according to claim 1, characterized in that, The slot width is 1mm, the height of the high-resistivity carbon paste below the slot is 13mm, the height of the high-resistivity carbon paste between the two slots is 2mm, and the height of the high-resistivity carbon paste above the slot is 3mm.

5. The wideband bandwidth metamaterial absorber covering L, S, C, X, and Ku bands according to claim 1 or 2, characterized in that, The support layer is 12mm long and wide, and 5.45mm thick.

6. The wideband bandwidth metamaterial absorber covering L, S, C, X, and Ku bands according to claim 1, characterized in that, The magnetic material layer has a length and width of 12mm and a thickness of 1.05mm.

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