CN111293440A - Ultra-thin wave absorber based on deep sub-wavelength slit - Google Patents
Ultra-thin wave absorber based on deep sub-wavelength slit Download PDFInfo
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- CN111293440A CN111293440A CN202010077295.8A CN202010077295A CN111293440A CN 111293440 A CN111293440 A CN 111293440A CN 202010077295 A CN202010077295 A CN 202010077295A CN 111293440 A CN111293440 A CN 111293440A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/002—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of materials engineered to provide properties not available in nature, e.g. metamaterials
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/003—Light absorbing elements
Abstract
The invention discloses an ultrathin wave absorber based on a deep sub-wavelength slit, wherein the thickness of a unit structure of the ultrathin wave absorber is in a deep sub-wavelength scale, namely a hundredth wavelength magnitude and below, the ultrathin wave absorber is divided into three layers along the height direction, a metal patch, a dielectric spacing layer and a metal back plate are respectively arranged from top to bottom, and an air slit with a deep sub-wavelength width is arranged between every two adjacent metal patches; the dielectric spacing layer is made of low-loss material with loss tangent tanδ<0.01, or no damage to the material; the wave absorption is realized by changing the size of the metal patch and adjusting the thickness of the medium spacing layer to change the wave absorption wavelength, and the microwave-absorbing material can work in various frequency bands from terahertz to microwave to radio frequency. The thickness of the wave absorbing device is very thin, the thickness of the wave absorbing device is reduced from the traditional one tenth wavelength order to one hundredth wavelength order, the thickness is very thin, the weight is light, and the wave absorbing device has certain flexibility; can be used forThe cost is reduced by adopting the mature circuit board process for manufacturing; the wave absorbing effect is insensitive to the incident angle, has the conformal advantage and can cover a curved surface.
Description
Technical Field
The invention belongs to the field of electromagnetic fields and electromagnetic waves, and particularly relates to an ultrathin wave absorber based on a deep sub-wavelength slit.
Background
The wave absorber has wide and important application in the fields of stealth, detection, sensing and the like. In many application scenarios, it is desirable to reduce the thickness of the wave-absorbing structure, thereby reducing the thickness and weight of the device, or improving the sensitivity and response speed of the device. When natural materials are adopted for electromagnetic absorption, the materials need to have very high material loss, and the thickness of the structure is usually about one quarter wavelength; when further reduction of the thickness of the structure is required, special materials such as ferromagnetism need to be used. This undoubtedly increases the manufacturing cost, and at the same time, this approach cannot be generalized to terahertz and other bands, because suitable ferromagnetic materials cannot be found in these bands. In recent years, the field of metamaterials is developed vigorously, and new design flexibility is brought to the wave-absorbing structure. The metamaterial wave absorber is generally formed by arranging subwavelength resonance structures, and the wave absorbing structure can be matched with the free space in impedance (the impedance of the free space is 377 ohms) by adjusting the amplitude and the phase of a resonance mode of an electric dipole and a magnetic dipole, so that a perfect wave absorbing effect can be still obtained under the subwavelength thickness. The thickness of the metamaterial absorber is typically a few tenths of the operating wavelength. If the structure thickness is further reduced, the wave absorbing effect is deteriorated.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide an ultrathin wave absorber based on a deep sub-wavelength slit.
An ultrathin wave absorber based on a deep sub-wavelength slit is a two-dimensional periodic structure, the thickness of a unit structure of the ultrathin wave absorber is of a deep sub-wavelength scale, namely, the order of one hundredth wavelength and below, the unit structure is divided into three layers along the height direction, metal patches, a dielectric spacing layer and a metal back plate are respectively arranged from top to bottom, and an air slit with a deep sub-wavelength width is arranged between every two adjacent metal patches; the dielectric spacing layer is made of low-loss material with loss tangent tanδ<0.01, or no damage to the material; the wave absorption is realized by changing the size of the metal patch and adjusting the thickness of the medium spacing layer to change the wave absorption wavelength, and the microwave-absorbing material can work in various frequency bands from terahertz to microwave to radio frequency.
The metal patch is square or annular in a square lattice form, or hexagonal or annular in a hexagonal lattice form; the material of the metal patch includes, but is not limited to, copper, iron, gold, silver, aluminum, and alloys thereof.
The medium spacing layer comprises but is not limited to a polytetrafluoroethylene plate, a polypropylene plate and air.
The metal back plate is a continuous metal film, and the material includes but is not limited to copper, iron, gold, silver, aluminum and alloys thereof.
The invention has the beneficial effects that:
the wave absorbing device has the outstanding advantages that the thickness is very thin and far thinner than that of the traditional wave absorbing device, and the thickness of the wave absorbing device is reduced from the magnitude of one tenth of wavelength to the magnitude of one hundredth of wavelength; the device is light in weight and has certain flexibility due to the thin thickness; the structure is simple, the process of a mature circuit board can be adopted for manufacturing, and the cost is reduced; the wave absorbing effect is insensitive to the incident angle, the device has the conformal advantage, and the device can cover a curved surface.
Drawings
FIG. 1 is a schematic diagram (three-dimensional) of a unit structure of an ultrathin wave absorber based on a deep subwavelength slit;
FIG. 2 is a schematic diagram (cross section) of a unit structure of an ultrathin wave absorber based on a deep sub-wavelength slit;
FIG. 3 graph of the measurement of the width and period of the metal patch in example 1;
FIG. 4 is a graph of the measurement of the total thickness of the structure of example 1;
FIG. 5 reflectance of example 1 in the frequency range of 1.8GHz-2.6GHz (simulation results).
Detailed Description
In order to realize a wave absorbing device with a deep sub-wavelength (one percent wavelength order and below) thickness, a three-layer wave absorbing structure of a metal patch, a medium spacing layer and a metal back plate is invented, and an air slit between the metal patches needs to have a deep sub-wavelength width. The narrow slits can help to maintain the balance of material absorption loss and radiation leakage loss of the wave-absorbing resonance unit structure, or the resonance frequency is red-shifted through strong interaction with the resonance unit structure, so that the wave absorber can still obtain perfect wave-absorbing effect when the low-loss or lossless medium spacing layer is very thin. On the whole, the structure has good wave absorbing effect, mature and cheap printed circuit board technology can be utilized in a microwave band, and the thickness can be as small as less than one of three to four hundredths of wavelength. By means of size scaling, the proposed wave absorber can work in various frequency bands from radio to terahertz.
The invention is further illustrated below with reference to the figures and examples.
The wave absorber is a two-dimensional periodic structure, the unit structure of the wave absorber is shown in figures 1 and 2, the wave absorber is divided into three layers along the height direction, and a metal patch, a medium spacing layer and a metal back plate for reflection (the thicknesses of the metal patch, the medium spacing layer and the metal back plate are respectively shown in the figure) from top to bottomt m、t dAndt m). Taking the square patches distributed in a tetragonal lattice, the period in the plane isp x =p y=pThe length and width of the patch arel x =l y =l. Between adjacent metal sheets is an air slit with a width ofξ=p–l(see FIG. 2). The electrical conductivity of the metal isσThe relative dielectric constant of the medium isεAnd loss tangent tanδ。
Thickness of metalt mWhen the microwave absorbing effect is larger than the skin depth, the microwave absorbing effect is not influenced, the typical value of the copper coating process can be selected in the microwave band,t m= 18 μm. Width of air slitξThe specific value can be determined by combining the processing technology, and the control is carried out in a deep sub-wavelength range. The dielectric spacer layer needs to be made of low-loss material, and the larger the dielectric constant is, the longer the cell side length islThe smaller may be; the smaller the loss tangent is, the smaller the dielectric layer thickness can be, and the reasonable selection needs to be made according to a material library.
Determining good operating frequencyf(wavelength)λ) Then, the side length of the patchlPrefetchingλ/2/√εAnd presetting the thickness of the medium interval layert d(e.g., one-three hundredths of the predetermined wavelength). The reflectivity of the wave absorber is calculated by numerical simulation software (such as CST Microwave Studio)R. Since the transmission is zero (incident waves are blocked by the metal backplate), the absorption is directly proportionalA= 1 –RAnd (6) performing calculation. FixingξScanning oft dSo thatAApproximately 1; fine tuninglSo that the resonant absorption peak frequency exactly matches the desired operating frequency. This is because at the deep sub-wavelength scale,ξandt dthe effect is not significant for the resonant absorption peak frequency,lfor absorption rateAThe influence of (a) is not great. Fine tuning over several cyclest dAndlthe values of these two quantities can then be determined. Slit width with other parameters unchangedξIt affects the thinness achievable with the dielectric spacer layer, generally smaller is better.
Example 1
The operating frequency was set at 2.21GHz and the operating wavelength at 135.7 mm. The dielectric material is selected from a low-loss doped polytetrafluoroethylene plate,ε= 3.6， tanδ= 0.004. The metal material is chosen to be copper, with a thickness of 18 μm, which is typical for copper-clad processes. .
The side length of the metal patch is set asl≈λ/2/√ε= 34.3 mm, the thickness of the dielectric spacer layer is set tot d=λ/300 = 0.45 mm, and the width of the air slit between the patches is set to 0.5 mm. Scanning with CSTt dAndland the final scale parameter is obtained after the fine adjustment is carried out twice in a circulating way,t d= 0.25 mm，l= 35 mm。
the material production and the structural processing can be realized by means of mature plate manufacturers and circuit board processing manufacturers. The produced wave absorber is shown in figures 3 and 4, and the width and the thickness of the wave absorber accord with the design values. The simulated wave absorbing effect (reflection coefficient amplitude) of the wave absorbing structure is shown in fig. 5. The figure shows that the wave-absorbing structure has a narrow-band strong absorption peak at the frequency of 2.21 GHz.
The embodiments in the above description can be further combined or replaced, and the embodiments are only described as preferred embodiments of the present invention, and do not limit the concept and scope of the present invention, and various changes and modifications made to the technical solution of the present invention by those skilled in the art without departing from the design concept of the present invention belong to the protection scope of the present invention. The scope of the invention is given by the appended claims and any equivalents thereof.
Claims (4)
1. An ultrathin wave absorber based on a deep sub-wavelength slit is characterized in that the wave absorber is a two-dimensional periodic structure, the thickness of a unit structure of the wave absorber is in a deep sub-wavelength scale, namely one hundredth wavelength magnitude and below, the wave absorber is divided into three layers along the height direction, a metal patch, a medium spacing layer and a metal back plate are respectively arranged from top to bottom, and an air slit with a deep sub-wavelength width is arranged between every two adjacent metal patches;
the dielectric spacing layer is made of low-loss material with loss tangent tanδ<0.01, or no damage to the material;
the wave absorption is realized by changing the size of the metal patch and adjusting the thickness of the medium spacing layer to change the wave absorption wavelength, and the microwave-absorbing material can work in various frequency bands from terahertz to microwave to radio frequency.
2. The ultra-thin absorber of claim 1, wherein said metal patches are square or circular in a square lattice form, or hexagonal or circular in a hexagonal lattice form; the material of the metal patch includes, but is not limited to, copper, iron, gold, silver, aluminum, and alloys thereof.
3. The ultra-thin absorber of claim 1 wherein said dielectric spacer layer comprises but is not limited to teflon sheet, polypropylene sheet, air.
4. The ultra-thin absorber of claim 1, wherein the metal back plate is a continuous metal film, and the material includes but is not limited to copper, iron, gold, silver, aluminum, and alloys thereof.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113506993A (en) * | 2021-06-18 | 2021-10-15 | 电子科技大学 | Medium type periodic structure with high frequency and low frequency |
| CN114913842A (en) * | 2022-04-29 | 2022-08-16 | 浙江大学 | Difunctional acoustics plane superlens |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009159588A (en) * | 2007-12-03 | 2009-07-16 | Shuho:Kk | Antenna for cellular phone or personal computer |
| CN103746191A (en) * | 2014-01-08 | 2014-04-23 | 中电科技扬州宝军电子有限公司 | Ultra-compact metamaterial wave-absorbing unit |
| US20190257986A1 (en) * | 2016-10-05 | 2019-08-22 | Agency For Science, Technology And Research | Diffractive optical element and method of forming thereof |
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- 2020-01-27 CN CN202010077295.8A patent/CN111293440A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009159588A (en) * | 2007-12-03 | 2009-07-16 | Shuho:Kk | Antenna for cellular phone or personal computer |
| CN103746191A (en) * | 2014-01-08 | 2014-04-23 | 中电科技扬州宝军电子有限公司 | Ultra-compact metamaterial wave-absorbing unit |
| US20190257986A1 (en) * | 2016-10-05 | 2019-08-22 | Agency For Science, Technology And Research | Diffractive optical element and method of forming thereof |
Non-Patent Citations (1)
| Title |
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| B.X. KHUYEN ET AL: "Ultrathin metamaterial-based perfect absorbers for VHF and THz bands", 《CURRENT APPLIED PHYSICS》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113506993A (en) * | 2021-06-18 | 2021-10-15 | 电子科技大学 | Medium type periodic structure with high frequency and low frequency |
| CN113506993B (en) * | 2021-06-18 | 2022-05-03 | 电子科技大学 | Medium type periodic structure with high frequency and low frequency |
| CN114913842A (en) * | 2022-04-29 | 2022-08-16 | 浙江大学 | Difunctional acoustics plane superlens |
| CN114913842B (en) * | 2022-04-29 | 2023-03-24 | 浙江大学 | Difunctional acoustics plane superlens |
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Application publication date: 20200616 |