Absorption and transmission integrated metamaterial structure with wave-transparent window capable of being dynamically opened and closed

Abstract

The invention provides an absorption and transmission integrated metamaterial structure with a wave-transparent window capable of being dynamically opened and closed, and belongs to the technical field of novel artificial electromagnetic materials, the metamaterial structure is formed by periodically arranging metamaterial structure units, the unit cycle of the metamaterial structure units is 15.0 mm, and the unit cycle of the metamaterial structure units is 15.0 mm. The metasurface comprises a double-layer spiral line chiral metasurface unit, a patch mesh complementary structure, a dielectric substrate layer, a carbon-based resistive film and a PIN diode, the metal structure layer comprises a chiral wave-absorbing layer and an active wave-transmitting layer, a plurality of dielectric substrate layers are arranged, the chiral wave-absorbing layer and the active wave-transmitting layer are respectively arranged on different dielectric substrate layers from top to bottom, the carbon-based resistive film is printed in a notch of the chiral wave-absorbing layer, and the PIN diode is printed in a notch of the active wave-transmitting layer. The wave-transparent window can be dynamically opened and closed in the wave band of 7-9.6 GHz, and efficient absorption can be achieved in the out-of-band frequency bands of 3-6 GHz and 11-21 GHz. The problems of wave absorption and wave transmission compatible design, dynamic opening and closing of the broadband wave transmission window and the like are effectively solved, electromagnetic and mechanical bearing functions are compatible, and the antenna can be applied to a multifunctional electromagnetic integrated system and an intelligent antenna housing system.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel artificial electromagnetic materials, and in particular relates to an absorption-transmission integrated metamaterial structure with a wave-transmitting window capable of dynamic switching. Background Art

[0002] In the past decade, metasurfaces have attracted great interest due to their flexible manipulation of electromagnetic wave surfaces. Metasurfaces are artificial electromagnetic surfaces designed by periodic or quasi-periodic arrangement of subwavelength-sized units. As a two-dimensional form of metamaterials, they not only inherit the unique electromagnetic properties of metamaterials, but also have the advantages of low loss, simple manufacturing, light weight, and high integration. In particular, metamaterial absorbers have broad application prospects in microwave and terahertz engineering, and have therefore developed rapidly in the past decade. Compared with traditional electromagnetic absorbers, metamaterial absorbers have the following advantages. First, metamaterial absorbers can arbitrarily control dielectric constants and magnetic permeabilities, and absorb electromagnetic wave energy by achieving impedance matching in free space, so perfect absorption can be achieved even on extremely thin substrates. Second, metamaterial absorbers can be manufactured using traditional printed circuit board (PCB) processes. Therefore, compared with traditional ferrite-based electromagnetic absorbers, the total cost is relatively low.

[0003] However, most passive metamaterial absorbers have a single fixed function and a fixed working mode in a specific working frequency band, and cannot be dynamically adjusted, which makes it difficult to meet the demand for multifunctional and intelligent devices. With the development of reconfigurable mechanisms, active metamaterial absorbers that can realize dynamic modulation functions have also developed rapidly. In particular, active metamaterial absorbers with integrated absorption and penetration will respond differently according to changes in external conditions, realize functional reconfiguration and reuse, and are of great significance in many applications such as electromagnetic aperture stealth and smart antenna cover design. However, the existing integrated absorption and penetration reconfigurable metasurface technology still has many defects. For example, most of the current active metamaterial absorbers cannot achieve high-efficiency absorption and compatible design with wave-transmitting window design, the bandwidth of the wave-transmitting window is generally narrow, the wave-transmitting window has large loss, and the wide-angle adaptability is poor, which makes it difficult to meet the application requirements of electromagnetic aperture broadband, high efficiency, and omnidirectional stealth design. Summary of the invention

[0004] The present invention proposes an integrated absorption and transmission metamaterial structure with a wave-transmitting window that can be dynamically switched, which breaks through the dynamic switching technology of the wave-transmitting window of the antenna cover and the compatible design technology of in-band wave transmission and out-of-band absorption, and solves the bottleneck problems such as the difficulty in expanding the wave-transmitting bandwidth, large wave-transmitting window loss, and poor wide-angle adaptability. It has the characteristics of high integration and mass production, is compatible with electromagnetic and mechanical bearing functions, and can be used in multifunctional electromagnetic integrated systems and antenna cover systems.

[0005] The technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides an integrated absorption and transmission metamaterial structure with a wave-transmitting window that can be dynamically switched, wherein the metamaterial structure is composed of periodically arranged metamaterial structural units, and the metamaterial structural units are prepared by the following steps:

[0007] Step 1: Design the absorbing part of the metamaterial structural unit. The absorbing part includes a double-layer helical chiral metastructure unit. The double-layer helical chiral metastructure unit has the same structural shape and is composed of four helices rotated 90° along the central origin. The mathematical expression of the helices in the polar coordinate system is:

[0008]

[0009] The parameters g0 = 0.2, g1 = 0.035, g2 = 0.15, and the value range of t is (0, 5π / 2);

[0010] Step 2: Designing an active frequency selection part of the metamaterial structural unit, the active frequency selection part includes a patch grid complementary structure, and the patch grid complementary structure includes a first square structure metal patch layer, a second square structure metal patch layer and a metal grid strip structure;

[0011] Step 3: Design the dielectric substrate layer, which includes the first substrate layer, the second substrate layer, the third substrate layer and the fourth substrate layer from top to bottom. The thickness of the first substrate layer and the second substrate layer is 0.1375 mm, and the thickness of the air layer between them is 5 mm. The thickness of the second substrate layer and the third substrate layer is 1.575 mm, and the thickness of the air layer between them is 8 mm. The third substrate layer and the fourth substrate layer are pressed together;

[0012] Step 4: Print the double-layer helical chiral meta-structure unit on the front of the first substrate layer and the second substrate layer respectively; print the first square structure metal patch layer and the second square structure metal patch layer on the front of the third substrate layer and the fourth substrate layer respectively, and print the metal grid strip structure on the back of the third substrate layer.

[0013] In some embodiments, in step 1, the width of the spiral line is 0.15 mm.

[0014] In some embodiments, the tail of the spiral line is connected to a vertical metal line or a horizontal metal line, and a carbon-based resistor film is loaded in the vertical metal line and the horizontal metal line. The carbon-based resistor film has a length of 1.1 mm and a width of 0.2 mm.

[0015] In some embodiments, the sheet resistance of the carbon-based resistor film on the first substrate layer is 150Ω / m^2, and the sheet resistance of the carbon-based resistor film on the second substrate layer is 90Ω / m^2.

[0016] In some embodiments, the first square structure metal patch layer and the second square structure metal patch layer are both composed of multiple square metal patch units, the width of the square metal patch unit is 6.5 mm, a vertical metal feed line is arranged between two adjacent square metal patch units on the third substrate layer, and a horizontal metal feed line is arranged between two adjacent square metal patch units on the fourth substrate layer. Notches are arranged on the vertical metal feed line and the horizontal metal feed line, and PIN diodes are loaded at the notches to realize dynamic switching of the switch state of the wave-transmitting window.

[0017] In some embodiments, the line width of the vertical metal feed line and the horizontal metal feed line are both 0.35 mm, and the gap length is 0.3 mm.

[0018] In some embodiments, the line width of the metal grid structure is 2.5 mm, and the distance between two grids in the metal grid structure is 5 mm.

[0019] In some embodiments, the metamaterial structure realizes dynamic switching of the wave-transmitting window in the 7-9.6 GHz band and realizes efficient absorption in the out-of-band frequency bands of 3-6 GHz and 11-21 GHz.

[0020] In a second aspect, the present invention provides an application of the absorbent-transmitter-in-one metamaterial structure with a wave-transmitting window that can be dynamically switched in a multifunctional electromagnetic integrated system or a smart antenna cover system.

[0021] Beneficial effects of the present invention:

[0022] 1. The wave-transmitting window provided by the present invention can dynamically switch the absorption and transmission integrated metamaterial structure by loading a resistive film structure in a double-layer chiral absorption layer structure to achieve efficient and selective absorption, and combines parallel resonant branches and other methods to achieve broadband windowing of the absorbing material.

[0023] 2. The absorbent-transmitter metamaterial structure with a wave-transmitting window that can be dynamically switched provided by the present invention realizes dynamic switching of the wave-transmitting window by integrating a PIN diode. The control method is simple and can be used for the integration of other functions.

[0024] 3. The present invention significantly reduces active components, lowers power consumption, and improves passband wave transmission efficiency by optimizing the unit structure and feeding network.

[0025] 4. The present invention adopts a resistor film to replace the traditional chip resistor to achieve wave absorption, improves the composite molding ability of the material, and facilitates integration and mass production.

[0026] 5. The absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched provided in the embodiment of the present invention can realize dynamic switching of the wave-transmitting window in the 7-9.6 GHz band and achieve efficient absorption in the out-of-band frequency bands of 3-6 GHz and 11-21 GHz.

[0027] 6. The present invention effectively solves the problems of wave absorption, wave transmission compatible design, dynamic switching of broadband wave-transmitting windows, etc. It is compatible with electromagnetic and mechanical bearing functions and can be applied to multifunctional electromagnetic integrated systems and intelligent antenna cover systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is an overall diagram of the present invention;

[0030] Figure 2 It is a split diagram of the present invention;

[0031] Figure 3 It is a simulated transmission coefficient diagram of the bottom wave-transmitting metamaterial structure in the present invention;

[0032] Figure 4 is an equivalent circuit model diagram of the present invention;

[0033] Figure 5 is a diode equivalent circuit diagram of the present invention;

[0034] Figure 6 The figure is a diagram of the simulated reflection coefficient and absorption result of a single-layer chiral absorbing layer in the present invention;

[0035] Figure 7 The figure is a simulated reflection coefficient and absorption result diagram of the double-layer chiral absorbing layer in the present invention;

[0036] Figure 8 is a simulated transmission coefficient diagram of the present invention;

[0037] Fig. 9 This is a diagram of the simulated wave absorption result of the present invention.

[0038] Among them, 1. first substrate layer; 2. second substrate layer; 3. third substrate layer; 4. fourth substrate layer; 5. spiral line; 6. vertical metal line; 7. horizontal metal line; 8. carbon-based resistor film; 9. square metal patch unit; 10. metal grid structure; 11. PIN diode; 12. vertical metal feed line; 13. horizontal metal feed line. DETAILED DESCRIPTION

[0039] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0040] When the incident wave irradiates the integrated metamaterial structure, the ideal wave-transmitting window requires that the incident wave in the frequency band can be fully transmitted through the high-frequency absorbing surface and the low-frequency absorbing surface. In order to ensure the performance of wave transmission, the designed absorbing structure should basically ensure that the transmission loss of the incident wave through the wave-transmitting window is zero; at the same time, the performance of the underlying bandpass FSS wave-transmitting window should also allow the incident wave in the wave-transmitting frequency band to pass completely without obstacles. At the same time, the bandpass FSS completely reflects the incident wave outside the passband to ensure good absorption of the absorbing surface. Considering the partial influence of multi-layer surface coupling, the electromagnetic characteristics of the overall structure should be optimized after the upper and lower surfaces that meet the requirements of the wave-transmitting window are designed to achieve the wave-transmitting design goal.

[0041] The present embodiment provides an integrated absorption and transmission metamaterial structure with a wave-transmitting window that can be dynamically switched. The metamaterial structure is composed of periodically arranged metamaterial structural units, and the period of the metamaterial structural units is 15.0 mm.

[0042] The metamaterial structural unit is prepared by the following steps:

[0043] First, the absorbing part of the metamaterial structural unit is designed. The absorbing part includes a double-layer helical 5 chiral metastructure unit. The double-layer helical 5 chiral metastructure unit has the same structural shape and is composed of four helical lines 5 rotated 90° along the central origin. The mathematical expression of helical line 5 in the polar coordinate system is:

[0044]

[0045] The parameters are g0=0.2, g1=0.035, g2=0.15, the value range of t is (0, 5π / 2), and the width of the spiral line 5 is 0.15 mm.

[0046] The tail of the spiral line 5 is connected to the vertical metal line 6 or the horizontal metal line 7. The vertical metal line 6 and the horizontal metal line 6 are loaded with a carbon-based resistor film 8. The length of the carbon-based resistor film 8 is 1.1 mm and the width is 0.2 mm. The square resistance of the carbon-based resistor film 8 on the first substrate layer 1 is 150Ω / m^2, and the square resistance of the carbon-based resistor film 8 on the second substrate layer 2 is 90Ω / m^2.

[0047] The single-layer helical 5-chiral superstructure unit is simulated, and the performance is as follows Figure 6 As shown in the simulation results, the reflectivity at 16-21GHz is less than -10dB and the absorption rate is higher than 80%, which indicates that the electromagnetic wave is almost completely reflected and efficient absorption is achieved. The double-layer chiral absorption layer is simulated, and the performance is shown in Figure 7 The simulation results show that the reflectivity at 4-6GHz and 11-18GHz is less than -10dB, and the absorption rate is higher than 80%, which indicates that the electromagnetic waves are almost completely reflected and efficient absorption is achieved.

[0048] Next, the active frequency selection part of the metamaterial structure unit is designed. The active frequency selection part includes a patch grid complementary structure. The patch grid complementary structure includes a first square structure metal patch layer, a second square structure metal patch layer and a metal grid bar structure 10. The metal grid bar structure 10 is added between the first square structure metal patch layer and the second square structure metal patch layer.

[0049] The first square structure metal patch layer and the second square structure metal patch layer are both composed of a plurality of square metal patch units 9, and the width of the square metal patch unit 9 is 6.5 mm. Vertical metal feed lines 12 are loaded between the square metal patch units 9 in the first square structure metal patch layer, and horizontal metal feed lines 13 are loaded between the square metal patch units 9 in the second square structure metal patch layer. Notches are provided on the vertical metal feed lines 12 and the horizontal metal feed lines 13, and PIN diodes 11 are loaded at the notches, that is, the PIN diodes 11 are respectively placed in the x-direction and the y-direction of the square gap patch to realize dynamic switching of the switch state of the wave-transmitting window. When the diodes in both directions are in conduction, that is, in the "ON" state, the wave-transmitting metamaterial fully reflects the incident electromagnetic waves; when the two diodes are in the off state, that is, in the "OFF" state, the wave-transmitting metamaterial fully transmits the incident electromagnetic waves at 7-10GHz, such as Figure 3 As shown, since all PIN diodes 11 are arranged in series, the feeding is simple and easy to implement.

[0050] The line width of the vertical metal feed line 12 and the horizontal metal feed line 13 are both 0.35 mm, and the length of the gap is 0.3 mm. The line width of the metal mesh bar structure 10 is 2.5 mm, and the distance between two bars in the metal mesh bar structure 10 is 5 mm.

[0051] The equivalent circuit model helps to understand the working principle of AFSS. The equivalent circuit of the upper and lower square metal patch layers is similar to that of ordinary patches, which is equivalent to L a and C a The series resonant circuit. L a is the equivalent inductance of the square patch, C a represents the gap capacitance between the two patches. The two dielectric layers are represented by two short transmission lines, whose characteristic impedance is, where Z0 is the characteristic impedance of free space, ε r is the relative dielectric constant of the substrate. A short transmission line can be connected using an LC resonant circuit (L t , C t) instead. The middle grid can be equivalent to the parallel inductance L m . Figure 4 The equivalent circuit model of the integrated metamaterial structure is shown. When the PIN diode 11 is turned on, it can be equivalent to a series circuit of L and R. When it is turned off, the PIN diode 11 can be equivalent to a series circuit of L and C. In this design, the type of PIN diode 11 is MADP-000907-14020. According to the data sheet of PIN diode 11, the equivalent parameters of PIN diode 11 are L s =30pH, R on =7.8Ω, C off =0.025pF, such as Figure 5 shown.

[0052] For the impedance absorption surface of the upper layer, the loss of electromagnetic waves by the absorber mainly includes three mechanisms: resistance loss, dielectric electric loss, and magnetic loss. Resistance loss is caused by loading lossy components such as lumped resistors or high resistance surfaces. The electric field causes macroscopic currents. The current passes through the resistors, and the electrical energy is converted into heat energy by the resistors and consumed. Dielectric electric loss is caused by the absorption and consumption of the incident wave energy penetrating the dielectric substrate. The dielectric electric loss capacity is positively correlated with its electric loss tangent. The magnetic loss capacity is also positively correlated with the magnetic loss tangent. This design uses the method of loading a resistive film on the chiral structure to achieve low-frequency and high-frequency wave absorption respectively. At the same time, the structure has good selective wave absorption performance and does not affect the transmission of the wave transmission frequency band.

[0053] In addition, the dielectric substrate layer is designed, and the dielectric substrate selected for the optimized absorbing part is Rogers RT5880, with a dielectric constant of εr=2.2.

[0054] The dielectric substrate layers include, from top to bottom, a first substrate layer 1, a second substrate layer 2, a third substrate layer 3 and a fourth substrate layer 4. The thickness of the first substrate layer 1 and the second substrate layer 2 is 0.1375 mm, and the thickness of the air layer therebetween is 5 mm. The thickness of the second substrate layer 2 and the third substrate layer 3 is 1.575 mm, and the thickness of the air layer therebetween is 8 mm. The third substrate layer 3 and the fourth substrate layer 4 are pressed together.

[0055] The double-layer helix 5 chiral metastructure units are printed on the front sides of the first substrate layer 1 and the second substrate layer 2 respectively; the first square structure metal patch layer and the second square structure metal patch layer are printed on the front sides of the third substrate layer 3 and the fourth substrate layer 4 respectively, and the metal grid bar structure 10 is printed on the back side of the third substrate layer 3.

[0056] The material of the above-mentioned wave absorbing part and the active frequency selection part is copper. The conductivity of the copper is 5.8×10 7 S / m.

[0057] The composite structure is as follows Figure 1 As shown in the figure, from top to bottom are the absorbing part and the active frequency selection part. Figure 8 As shown in the figure, when the diode is in the off state, the transmittance is greater than 90% in the 7.4-9.3GHz range; when the diode is in the on state, the transmittance is less than 15% in the 7.4-9.3GHz range, achieving the switch between wave transmission and reflection. At the same time, the performance of the active wave-transmitting metamaterial structure before and after the composite does not change much, indicating that the upper impedance absorption surface does not affect the transmission of electromagnetic waves in the wave-transmitting frequency band. Fig. 9 As shown, in both states, the absorption in the range of 3-6 GHz is greater than 80%, and the average absorption in the range of 11-21 GHz is also greater than 80%.

[0058] The embodiments described above are only preferred specific implementation modes of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention belong to the protection scope of the present invention.

Claims

1. A metamaterial structure with a wave-transmitting window that can be dynamically switched, characterized in that: The metamaterial structure is composed of periodically arranged metamaterial structural units, and the metamaterial structural units are prepared by the following steps: Step 1: Design the absorbing part of the metamaterial structural unit. The absorbing part includes a double-layer helical chiral metastructure unit. The double-layer helical chiral metastructure unit has the same structural shape and is composed of four helices rotated 90° along the central origin. The mathematical expression of the helices in the polar coordinate system is: The parameters g0 = 0.2, g1 = 0.035, g2 = 0.15, and the value range of t is (0, 5π / 2); Step 2: Designing an active frequency selection part of the metamaterial structural unit, the active frequency selection part includes a patch grid complementary structure, and the patch grid complementary structure includes a first square structure metal patch layer, a second square structure metal patch layer and a metal grid strip structure; Step 3: Design the dielectric substrate layer, which includes the first substrate layer, the second substrate layer, the third substrate layer and the fourth substrate layer from top to bottom. The thickness of the first substrate layer and the second substrate layer is 0.1375 mm, and the thickness of the air layer between them is 5 mm. The thickness of the second substrate layer and the third substrate layer is 1.575 mm, and the thickness of the air layer between them is 8 mm. The third substrate layer and the fourth substrate layer are pressed together; Step 4: Print the double-layer helical chiral meta-structure unit on the front of the first substrate layer and the second substrate layer respectively; print the first square structure metal patch layer and the second square structure metal patch layer on the front of the third substrate layer and the fourth substrate layer respectively, and print the metal grid strip structure on the back of the third substrate layer.

2. The absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched according to claim 1, characterized in that: In step 1, the width of the spiral line is 0.15 mm.

3. The absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched according to claim 2, characterized in that: The tail of the spiral wire is connected to a vertical metal wire or a horizontal metal wire. The vertical metal wire and the horizontal metal wire are loaded with a carbon-based resistor film. The length of the carbon-based resistor film is 1.1 mm and the width is 0.2 mm.

4. The absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched according to claim 3 is characterized in that: The sheet resistance of the carbon-based resistor film on the first substrate layer is 150Ω / m^2, and the sheet resistance of the carbon-based resistor film on the second substrate layer is 90Ω / m^2.

5. The absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched according to claim 4, characterized in that: The first square structure metal patch layer and the second square structure metal patch layer are both composed of multiple square metal patch units. The width of the square metal patch unit is 6.5 mm. A vertical metal feed line is arranged between two adjacent square metal patch units on the third substrate layer. A horizontal metal feed line is arranged between two adjacent square metal patch units on the fourth substrate layer. Notches are arranged on the vertical metal feed line and the horizontal metal feed line. PIN diodes are loaded at the notches to realize dynamic switching of the switch state of the wave-transmitting window.

6. The absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched according to claim 5, characterized in that: The line width of the vertical metal feed line and the horizontal metal feed line are both 0.35 mm, and the notch length is 0.3 mm.

7. The absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched according to claim 4, characterized in that: The line width of the metal mesh bar structure is 2.5 mm, and the distance between two bars in the metal mesh bar structure is 5 mm.

8. The absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched according to claim 1, characterized in that: The metamaterial structure realizes dynamic switching of the wave-transmitting window in the 7-9.6 GHz band and realizes efficient absorption in the out-of-band frequency bands of 3-6 GHz and 11-21 GHz.

9. Application of the absorbent-transmitter integrated metamaterial structure with a wave-transmitting window that can be dynamically switched according to any one of claims 1 to 8 in a multifunctional electromagnetic integrated system or a smart antenna cover system.

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