A switchable absorbent-transmissive integrated material with polarization selectivity and high roll-off characteristics

Abstract

The present application belongs to the technical field of absorbing and permeating integrated material, and specifically provides a switchable absorbing and permeating integrated material with polarization selectivity and high roll-off characteristics, which is used to realize switching among absorbing and permeating integration, polarization selection and wave absorption mode. The present application is composed of two impedance layers and a frequency selective surface; and the PIN diode loaded on the active impedance layer and the FSS can be independently controlled in orthogonal polarization through a bias signal to realize polarization selectivity, and a transmission zero point is introduced in the FSS design to improve the roll-off characteristics of the transmission frequency band; at the same time, the FSS unit is a symmetrical structure, and can selectively pass electromagnetic waves of any linear polarization incidence, and has strong practicability. In summary, the present application has three working modes of absorbing and permeating integration, polarization selection and wave absorption mode, and realizes switching of the working mode through the diode, and has advantages of excellent performance, simple structure, low preparation cost and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of absorption and permeation integrated materials, and specifically provides a switchable absorption and permeation integrated material with polarization selectivity and high roll-off characteristics. BACKGROUND

[0002] As a device combining electromagnetic invisibility and filtering functions, absorptive-transmissive integrated materials have been widely studied in the past decade. According to the position of the transmission band and the absorption band, absorptive-transmissive integrated materials can be divided into A-T, T-A, and A-T-A types. However, the development of passive absorptive-transmissive integrated materials with static response is limited by their poor in-band shielding performance. To overcome this drawback of passive absorptive-transmissive integrated materials, researchers have studied switchable absorptive-transmissive integrated materials whose passband can be switched to a reflective or absorptive state. For example, Li et al. (R. Li, J. Tian, B. Jiang, Z. Lin, B. Chen, and H. Hu, “A Switchable Frequency Selective Rasorber With Wide Passband,” IEEE Antennas and Wireless Propagation Letters, vol. 20, no. 8, pp. 1567–1571, 2021, conference Name: IEEE Antennas and Wireless Propagation Letters.) proposed a switchable absorptive-transmissive integrated material based on a three-layer structure with a wide transmission band and an absorption band. However, this device is sensitive to polarization, which limits its practical application. Although Qian et al. (G. Qian, J. Zhao, X. Ren, K. Chen, T. Jiang, Y. Feng, and Y. Liu, “Switchable Broadband Dual-Polarized Frequency-Selective Rasorber / Absorber,” IEEE Antennas and Wireless Propagation Letters, vol. 18, no. 12, pp. 2508–2512, Dec. 2019, conference Name: IEEE Antennas and Wireless Propagation Letters.) proposed a switchable A-T-A device with a dual-polarization response, the resistance loaded on the Frequency Selective Surface (FSS) introduces a large Insertion Loss (IL) in its absorber mode.Accordingly, Bakshi et al. (S. C. Bakshi, D. Mitra, and F. L. Teixeira, “Wide-Angle Broadband Rasorber for Switchable and Conformal Application,” IEEE Transactions on Microwave Theory and Techniques, vol. 69, no. 2, pp. 1205-1216, Feb. 2021, conference Name: IEEE Transactions on Microwave Theory and Techniques.) proposed an A-T-A switchable absorptive-transmissive one-material with relatively low insertion loss and dual-polarization characteristics; however, the complex biasing network for controlling the PIN diodes degrades its operational performance, and the achieved transmission and absorption bandwidths are relatively narrow. Moreover, existing polarization-insensitive switchable one-materials exhibit poor roll-off characteristics.

[0003] On the other hand, reconfigurable metamaterials (MMs) with polarization selectivity have also been widely studied; for example, Jiang et al. (S. Jiang, X. Kong, L. Kong, X. Jin, and J. Yuan, “Switchable Polarization-Insensitive Frequency Selective Surface Reflector / Absorber With Low Profile by Using Magnetic Material,” IEEE Antennas and Wireless Propagation Letters, vol. 20, no. 10, pp. 2078-2082, Oct. 2021) designed and experimentally demonstrated a diode-based polarization-selective in-band switchable FSS reflector / absorber, a PIN diode was used to achieve switchable characteristics from in-band reflection and out-of-band absorption response to wideband absorption response. Kong et al. (L. Kong, X. Kong, S. Jiang, Y. Lee, L. Xing, and B. Bian, “A Great Wall-Inspired, Water-Based, Switchable Frequency-Selective Rasorber With Polarization Selectivity: Multifunctional, Polarization Selective, Independent Working States.” IEEE Antennas and Propagation Magazine, pp. 2-14, 2022) designed a water-based switchable absorptive-transmissive material with polarization selectivity using a Great Wall structure, the novelty of this design is that by injecting water into different channels, the switching of three different working states is achieved, by injecting (or draining) water into the unit cell (UC), the device state is switched independently in the polarization direction needed to achieve polarization selectivity. Compared with traditional MMs, these devices are more flexible, have higher integration, and are a better choice in certain specific applications.

[0004] In summary, switchable absorptive-transmissive materials with in-band shielding capability have broad application prospects; therefore, designing and implementing switchable absorptive-transmissive materials with polarization selectivity and high roll-off characteristics become the research focus of the present application. SUMMARY

[0005] In view of the problems in the background art, the present application aims to provide a switchable absorbing and permeable integrated material with polarization selectivity and high roll-off characteristics, to realize switching between absorbing and permeable integration, polarization selection and wave absorption mode. The present application is composed of two impedance layers (passive and active impedance layers) and a frequency selective surface (FSS); and the PIN diodes loaded on the active impedance layer and the FSS can be independently controlled in orthogonal polarization by a bias signal to realize polarization selectivity, and transmission zeros (TZs) are introduced in the FSS design to improve the roll-off characteristics of its transmission band; at the same time, the FSS unit is a symmetrical structure, which can select any linearly polarized incident electromagnetic wave, and has strong practicability.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0007] A switchable absorbing and permeable integrated material with polarization selectivity and high roll-off characteristics, from top to bottom, includes: a first metal patch layer 1, a first dielectric layer 2, a first air layer 3, a second metal patch layer 4, a second dielectric layer 5, a third metal patch layer 6, a second air layer 7, a fourth metal patch layer 8, a third dielectric layer 9, a fifth metal patch layer 10, a fourth dielectric layer 11, a sixth metal patch layer 12, a fifth dielectric layer 13, and a seventh metal patch layer 14; characterized in that:

[0008] The first metal patch layer 1 is arranged on the upper surface of the first dielectric layer 2, and the two together constitute the first impedance layer, the second metal patch layer 4 and the third metal patch layer 6 are arranged on the upper surface and the lower surface of the second dielectric layer 5 respectively, and the three together constitute the second impedance layer, and the seventh metal patch layer 14, the fifth dielectric layer 13, the sixth metal patch layer 12, the fourth dielectric layer 11, the fifth metal patch layer 10, the third dielectric layer 9, and the fourth metal patch layer 8 are stacked in order from bottom to top to constitute a frequency selective surface FSS.

[0009] Further, the first impedance layer is composed of MxN first impedance units arranged in an array, the first metal patch unit in the first impedance unit adopts a square ring patch loaded with a spiral inductor, the square ring patch is centrally symmetric about the center point of the dielectric layer, the square ring patch is arranged at the four peripheral edge positions of the dielectric layer, the square ring patch is loaded with a spiral inductor at the middle position of each side, the tail end of the wire spiral inductor is connected to the square ring through a bent metal wire, and the center end is connected to the square ring through a metal connecting line on the lower surface of the dielectric layer; the square ring patch is loaded with two first lumped resistors 16 on each side, and they are respectively located on the two sides of the spiral inductor.

[0010] Further, the second impedance layer is composed of MxN second impedance units arranged in an array, the second metal patch unit is arranged along the x-axis direction, the third metal patch unit is arranged along the y-axis direction, and both have the same structure; the metal patch unit is composed of a parallel LC resonance structure and two rectangular patches connected on both sides of the parallel LC resonance structure, a second lumped resistor 17 is loaded between the parallel LC resonance structure and the rectangular patch, and the unit structures are connected through the rectangular patch; the parallel LC resonance structure is composed of a resonant bent inductance line and a resonant rectangular patch in parallel, a PIN diode 19 is loaded between the rectangular patch and the parallel end, and a lumped capacitor 18 is loaded in the center of the bent inductance line; the third metal patch unit is translated along the x-axis and y-axis directions relative to the second metal patch unit by P1 / 2 and P1, which are the unit periods of the first and second impedance units; the second metal patch unit is translated along the y-axis relative to the first impedance unit by P1 / 2.

[0011] Further, the fourth metal patch layer 8 is composed of 2Mx2N fourth metal patch units arranged in an array, the fourth metal patch unit is arranged along the x-axis direction, and a PIN diode is loaded between adjacent fourth metal patch units; the fifth metal patch layer 10 is composed of 2Mx2N fifth metal patch units arranged in an array, the fifth metal patch unit is arranged along the y-axis direction, and a PIN diode is loaded between adjacent fifth metal patch units (the diode is arranged on the upper surface of the third dielectric layer 9 through a metal via); the fourth metal patch unit and the fifth metal patch unit have the same structure and are composed of a frequency-selective rectangular patch and a symmetrical trapezoidal transition patch connected on both sides thereof; the fifth metal patch unit is translated along the x-axis and y-axis relative to the fourth metal patch unit by P2 / 2, P2 is the unit period of the fourth and fifth metal patch units, and P2=P1 / 2; for the fourth metal patch unit and the fifth metal patch unit, every 2x2 subarray corresponds to a first impedance unit, and is translated along the x-axis and -y-axis relative to the first impedance unit by P1 / 4.

[0012] Further, the sixth metal patch layer is composed of 2Mx2N sixth metal patch units arranged in an array, the sixth metal patch unit includes: a frequency-selective bent inductance line and an interdigital capacitor, two frequency-selective bent inductance lines intersect to form a cross structure and are centrally symmetric, the frequency-selective bent inductance lines are respectively connected to the interdigital capacitor at both ends, and the interdigital capacitor is shared between adjacent units; the seventh metal patch unit is composed of 2Mx2N seventh metal patch units arranged in an array, the seventh metal patch unit adopts a centrally symmetric Jerusalem structure composed of a cross-shaped patch and a triangular patch connected to four ends thereof; for the sixth metal patch unit and the seventh metal patch unit, the unit period is P2, and every 2x2 subarray corresponds to a first impedance unit.

[0013] Further, M and N are not less than 5 to ensure the working performance of the absorption and transmission integrated material.

[0014] Further, in the switchable absorption-transmission integrated material, all PIN diodes are used as switching devices with the same structure (same model), and the switching of the working mode is realized by changing the on-off state of the switching devices; when the PIN diode is in the OFF state, it is regarded as a capacitor and recorded as state 0; when the PIN diode is in the ON state, it is regarded as a resistor with very small resistance and recorded as state 1; according to the on-off state of the PIN diode loaded by the second impedance layer and the frequency selection layer, the working mode is divided into four states:

[0015] Mode 00: all PIN diodes are off;

[0016] Mode 01: all PIN diodes in the second and fourth metal patch units are off; all PIN diodes in the third and fifth metal patch units are on;

[0017] Mode 10: all PIN diodes in the second and fourth metal patch units are on; all PIN diodes in the third and fifth metal patch units are off;

[0018] Mode 11: all PIN diodes are on;

[0019] In mode 00, the device is in the absorption-transmission integrated working state in the X and Y directions;

[0020] In mode 11, the device is in the wave-absorbing body working state in the X and Y directions;

[0021] In mode 10, the device operates as a polarization selection device, at this time, the in-band X polarized electromagnetic wave can be transmitted with low insertion loss (IL), while the in-band Y polarized wave is absorbed, realizing polarization selectivity;

[0022] In mode 01, the device operates as a polarization selection device, at this time, the in-band Y polarized electromagnetic wave can be transmitted with low insertion loss (IL), while the in-band X polarized wave is absorbed, realizing polarization selectivity.

[0023] From the working principle:

[0024] The distance from the first impedance layer and the second impedance layer to the frequency selective surface (FSS) is respectively one quarter of the wavelength corresponding to the low-frequency wave-absorbing center frequency and the high-frequency wave-absorbing frequency; the air thickness between the two impedance layers and the frequency selective layer and the size parameters of the specific structure of the wave-absorbing and wave-transmitting integrated material are adjusted, so that the impedance characteristics are well matched with the air, and good wave-absorbing characteristics and passband characteristics at low and high frequencies are realized. The roll-off characteristics of the passband are mainly determined by the FSS, and a transmission zero point (TZ) is introduced in the FSS design to improve the roll-off characteristics of the transmission band; the equivalent circuit model of the FSS is three pairs of inductors and capacitors connected in series, and the three pairs of series structures are separated by two dielectric substrates. The positions of the three transmission zero points are closely related to the LC parameters of the circuit, wherein the first layer structure (the fourth and fifth metal patch layers and the third dielectric layer) and the third layer structure (the seventh metal patch layer and the fifth dielectric layer) of the FSS correspond to two zero points at the high frequency on the right side of the transmission passband, and the second layer structure (the sixth metal patch layer and the fourth dielectric layer) of the FSS corresponds to a zero point at the low frequency on the left side of the transmission passband; the edge of the passband is adjusted by adjusting the position of the zero point to improve the roll-off characteristics of the passband.

[0025] In summary, the beneficial effects of the present application are:

[0026] The present application provides a switchable wave-absorbing and wave-transmitting integrated material with polarization selectivity and high roll-off characteristics, which has the following advantages:

[0027] 1. The present application is composed of two impedance layers (passive and active impedance layers) and a frequency selective surface (FSS), and the high roll-off characteristics of the transmission band are realized by introducing three transmission zero points (TZ) in the FSS design; the PIN diode on the active impedance layer and the FSS can be independently controlled as a polarization switch to realize polarization selectivity; at the same time, the switch device is a diode to realize the switching of the working mode, and the loading mode of this structure is relatively simple.

[0028] 2. The three-layer structure of the present application has a symmetric feature, so that the overall material has a dual-polarization characteristic; and the conduction or shutdown of the diode is controlled by direct current feeding, thereby controlling the opening or closing of the passband window, realizing a simple switchable means.

[0029] 3. The device of the present application has three working modes, namely wave-absorbing and wave-transmitting integrated, polarization selection and wave-absorbing mode; in the wave-absorbing and wave-transmitting integrated mode, the device has a wide passband of 27.5% (3.42-4.51GHz) partial bandwidth, and the two sides have an absorption band of 88.4% (1.27-3.2GHz) and 32.2% (4.69-6.25GHz) respectively; in the wave-absorbing mode, the absorption bandwidth reaches 142.9% (1-6GHz). In addition, when operating in the polarization selection mode, its performance is not significantly affected.

[0030] 4. The structure of the present application can be realized by a printed board process, which is low in cost and simple in processing. Attached Figure Description

[0031] Figure 1 This is a side view schematic diagram of the structural unit in the switchable absorbent-permeable integrated material with polarization selectivity and high roll-off characteristics of the present invention.

[0032] Figure 2 for Figure 1 The diagram shows the structure of the first impedance unit in the switchable permeable integrated material.

[0033] Figure 3 for Figure 1 The diagram shows the structure of the second impedance unit in the switchable permeable integrated material.

[0034] Figure 4 for Figure 1 The diagram shows the structure of the fourth and fifth metal patch units of the frequency selective surface (FSS) in the switchable absorbent integrated material.

[0035] Figure 5 for Figure 1 The diagram shows the structure of the sixth and seventh metal patch units of the frequency selective surface FSS in the switchable absorbent integrated material.

[0036] Figure 6 This is an equivalent circuit model diagram of the frequency selective surface (FSS) in this invention.

[0037] Figure 7 The image shows the electromagnetic simulation results of a switchable permeable integrated material with polarization selectivity and high roll-off characteristics in an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] This embodiment provides a switchable absorbent-permeable integrated material with polarization selectivity and high roll-off characteristics, as shown in the side view diagram below. Figure 1 As shown, from top to bottom, it includes: a first metal patch layer 1, a first dielectric layer 2, a first air layer 3, a second metal patch layer 4, a second dielectric layer 5, a third metal patch layer 6, a second air layer 7, a fourth metal patch layer 8, a third dielectric layer 9, a fifth metal patch layer 10, a fourth dielectric layer 11, a sixth metal patch layer 12, a fifth dielectric layer 13, and a seventh metal patch layer 14.

[0040] Furthermore, the first metal patch layer 1 is disposed on the upper surface of the first dielectric layer 2, and the two together constitute the first impedance layer. The first impedance layer is composed of an array of M×N first impedance units; the structure of the first impedance unit is as follows: Figure 2As shown, its first metal patch unit adopts a square ring patch with a loaded spiral inductor, such as... Figure 2 As shown in (a), the square ring patch is symmetrical about the center point of the dielectric layer. The square ring patch is located at the perimeter of the dielectric layer. A spiral inductor is loaded at the middle of each side of the square ring patch. The tail end of the spiral inductor line is connected to the square ring through a bent metal wire, and the center end is connected to the square ring through a metal connecting wire on the lower surface of the dielectric layer (achieved through a metal through-hole 15 penetrating the dielectric layer, as shown in (a)). Figure 2 As shown in (b)); the square ring patch has two first lumped resistors 16 loaded on each side, and they are located on both sides of the spiral inductor respectively.

[0041] In this embodiment, the line width of the line structure is 0.2mm, the line spacing of the spiral inductor is 0.2mm, the size of the spiral inductor is 1.9mm×3.9mm, the diameter of the metal through hole 15 is 0.3mm, the length of the metal connecting wire is 2.75mm, and the square ring patch structure is 0.2mm away from the edge of the dielectric layer.

[0042] Furthermore, the second metal patch layer 4 and the third metal patch layer 6 are respectively disposed on the upper and lower surfaces of the second dielectric layer 5, and the three together constitute the second impedance layer. The second impedance layer is composed of an array of M×N second impedance units; the second impedance units are as follows: Figure 3 As shown, its second metal patch unit is arranged along the x-axis direction (e.g. Figure 3 As shown in (a), the third metal patch unit is arranged along the Y-axis direction (as shown in the middle). Figure 3 As shown in (b), both adopt the same structure; the metal patch structure is composed of a parallel LC resonant structure and rectangular patches connected on both sides, with a second lumped resistor 17 loaded between the parallel LC resonant structure and the rectangular patches, and the unit structures are connected via the rectangular patches; the parallel LC resonant structure is composed of a resonant bent inductor line and a resonant rectangular patch connected in parallel, with PIN diodes 19 loaded between the rectangular patches and the parallel terminals respectively, and a lumped capacitor 18 loaded at the center of the bent inductor line; the third metal patch unit is translated relative to the second metal patch unit along the x-axis and y-axis directions by P1 / 2, respectively, where P1 is the unit period of the first and second impedance units, as shown in (b). Figure 3 As shown in (c); the second metal patch unit is translated P1 / 2 relative to the first impedance unit along the y-axis, as follows. Figure 3 As shown in (d), the dashed box in the figure indicates the location of the first impedance unit.

[0043] In this embodiment, the dimensions of the connecting rectangular patch are 5.8mm × 1.5mm, the dimensions of the resonant rectangular patch are 2.4mm × 0.5mm, the diode length is 1.8mm, and the bent inductor structure is Z-shaped with a line width of 0.2mm, a line spacing of 0.2mm, a bending width of 1.7mm, and a bending length of 3.9mm.

[0044] Further, the seventh metal patch layer 14, the fifth dielectric layer 13, the sixth metal patch layer 12, the fourth dielectric layer 11, the fifth metal patch layer 10, the third dielectric layer 9, and the fourth metal patch layer 8 are sequentially stacked from bottom to top to form the frequency selective surface FSS.

[0045] The fourth metal patch layer 8 is composed of 2M×2N fourth metal patch units arranged in an array, and the fourth metal patch units are arranged along the x-axis direction and loaded with PIN diodes between adjacent fourth metal patch units, as shown in (a) of FIG. 6. Figure 4 The fifth metal patch layer 10 is composed of 2M×2N fifth metal patch units arranged in an array, and the fifth metal patch units are arranged along the y-axis direction and loaded with PIN diodes between adjacent fifth metal patch units (the diodes are arranged on the upper surface of the third dielectric layer 9 through metal vias), as shown in (b) of FIG. 6. Figure 4 The fourth metal patch unit and the fifth metal patch unit have the same structure and are composed of a frequency-selective rectangular patch and two symmetrically connected trapezoidal transition patches on both sides thereof; the fifth metal patch unit is translated by P2 / 2 relative to the fourth metal patch unit along the x-axis and the y-axis, and P2 is the unit period of the fourth and fifth metal patch units, P2=P1 / 2, as shown in (c) of FIG. 6. Figure 4 For the fourth metal patch unit and the fifth metal patch unit, every 2×2 subarray corresponds to a first impedance unit, and is translated by P1 / 4 relative to the first impedance unit along the x-axis and the y-axis, as shown in (d) of FIG. 6, and the dashed box in the figure is the position of the first impedance unit. Figure 4

[0046] The sixth metal patch layer is composed of 2M×2N sixth metal patch units arranged in an array, and the sixth metal patch unit includes a frequency-selective bent inductive line and an interdigital capacitor, two frequency-selective bent inductive lines are cross-shaped and center-symmetric, and the two ends of the frequency-selective bent inductive line are respectively connected to the interdigital capacitor, and the adjacent units share the interdigital capacitor, as shown in (a) of FIG. 7. Figure 5 The seventh metal patch unit is composed of 2M×2N seventh metal patch units arranged in an array, and the seventh metal patch unit adopts a center-symmetric Jerusalem structure composed of a cross-shaped patch and a triangular patch connected to four ends thereof, as shown in (b) of FIG. 7. Figure 5 For the sixth metal patch unit and the seventh metal patch unit, the unit period is P2, and every 2×2 subarray corresponds to a first impedance unit.

[0047] ​In this embodiment, the width of the frequency-selected rectangular patch in the fourth metal patch unit is 1.5 mm, the width of the frequency-selected rectangular patch in the fifth metal patch unit is 2 mm, the length of the diode is 1.8 mm, and the length of the fourth metal patch unit (fifth metal patch unit) plus the length of the diode is equal to the unit period P2. In the sixth metal patch unit, the length of the interdigital capacitor finger is 4.5 mm, the width of the interdigital capacitor finger is 0.2 mm, the finger spacing is 0.2 mm, and the width of the frequency-selected bent inductor line is 0.2 mm; in the seventh metal patch unit, the width of the cross-shaped patch is 0.5 mm, the length of the cross-shaped patch is 4.2 mm, the base length of the triangular patch is 6 mm, and the spacing between the Jerusalem structures in adjacent seventh metal patch units is 0.3 mm. P1 = 20 mm, P2 = 10 mm. The dielectric layer is a radio frequency dielectric substrate, and the preferred model is F4B. The relative permittivity of the first dielectric layer is 3.0, the relative permittivity of the second, third, fourth, and fifth dielectric layers is 2.2, and the loss tangent is tan δ = 0.0015. The metal patch layer is a PCB printed circuit. The thickness of the first dielectric layer is 0.5 mm, the thickness of the first air layer is 17 mm, the thickness of the second dielectric layer is 0.5 mm, the thickness of the second air layer is 20 mm, the thickness of the third dielectric layer is 0.5 mm, the thickness of the fourth dielectric layer is 1.5 mm, and the thickness of the fifth dielectric layer is 1.5 mm. The lumped resistor loaded in the first metal patch layer is 200 ohms, and the lumped resistor loaded in the second and third metal patch layers is 150 ohms. The lumped capacitor loaded in the second and third metal patch layers is 18 pF. The PIN diode is Skyworks SMP1345, which has a typical capacitance value of 0.118 pF in the off state and a typical resistance value of 1 ohm in the on state, and the diodes in the structure use the same model.

[0048] As Figure 6The equivalent circuit model (ECM) of the FSS is shown, which is three pairs of series inductors and capacitors, and is separated by two dielectric substrates. In order to realize reconfigurability, the leftmost capacitor in the equivalent circuit model (in the dashed box) has been replaced by a PIN diode; when the PIN diode is OFF, it is regarded as a capacitor; when the PIN diode is ON, it is regarded as a resistor with a very small resistance. The positions of the three transmission zeros on both sides of the transmission passband are closely related to the circuit LC parameters. Among them, the first layer structure (the fourth and fifth metal patch layers and the third dielectric layer) and the third layer structure (the seventh metal patch layer and the fifth dielectric layer) of the FSS correspond to two zeros TZ2 and TZ3 at the high frequency on the right side of the transmission passband, and the second layer structure (the sixth metal patch layer and the fourth dielectric layer) of the FSS corresponds to the zero TZ1 at the low frequency on the left side of the transmission passband; by adjusting the circuit parameters Lf1 and Cf1 (or Lf2, Cf2; Lf3, Cf3), TZ2 (or TZ1; TZ3) can be changed individually. Therefore, the edges of the passband can be easily adjusted by adjusting the positions of the zeros to improve the roll-off characteristics of the passband.

[0049] As shown in Figure 7 The electromagnetic simulation result diagram of the present embodiment under the condition of periodic boundary condition and vertical incidence of electromagnetic wave is shown; wherein, Fig. (a) is the simulation result diagram of all PIN diodes being OFF (i.e. mode 00), Fig. (b) is the simulation result diagram of all PIN diodes in the second and fourth metal patch units being OFF and all PIN diodes in the third and fifth metal patch units being ON (i.e. mode 01), Fig. (c) is the simulation result diagram of all PIN diodes in the second and fourth metal patch units being ON and all PIN diodes in the third and fifth metal patch units being OFF (i.e. mode 10), and Fig. (d) is the simulation result diagram of all PIN diodes being ON (i.e. mode 11); as can be seen from the diagram, the absorption and transmission integrated material has a wide passband of 27.5% (3.42-4.51 GHz) partial bandwidth under the absorption and transmission integrated mode (mode 00), and has an absorption band of 88.4% (1.27-3.2 GHz) and 32.2% (4.69-6.25 GHz) on both sides, respectively. The absorption bandwidth realized under the absorption mode (mode 11) reaches 142.9% (1-6 GHz); the transmission passband realized has a high roll-off characteristic. In addition, when it is operated in the polarization selection mode (mode 10 or 01), its performance is not obviously affected.

[0050] The above merely provides the specific implementation of the present application, any feature disclosed in the specification can be replaced by other equivalent or similar purpose alternative features unless specifically described, and all features disclosed or all steps in the method or process can be combined in any manner except for mutually exclusive features and / or steps.

Claims

1. A switchable absorbent-transmissive integrated material having polarization selectivity and high roll-off characteristics, comprising, in order from top to bottom: The first metal patch layer (1), the first dielectric layer (2), the first air layer (3), the second metal patch layer (4), the second dielectric layer (5), the third metal patch layer (6), the second air layer (7), the fourth metal patch layer (8), the third dielectric layer (9), the fifth metal patch layer (10), the fourth dielectric layer (11), the sixth metal patch layer (12), the fifth dielectric layer (13), and the seventh metal patch layer (14) are characterized in that: The first metal patch layer is arranged on the upper surface of the first dielectric layer and together with the first dielectric layer forms a first impedance layer, the second metal patch layer and the third metal patch layer are arranged on the upper surface and the lower surface of the second dielectric layer respectively and together with the second dielectric layer form a second impedance layer, and the seventh metal patch layer, the fifth dielectric layer, the sixth metal patch layer, the fourth dielectric layer, the fifth metal patch layer, the third dielectric layer, and the fourth metal patch layer are sequentially stacked from bottom to top to form a frequency selective surface (FSS); The first impedance layer is formed by array arrangement of MxN first impedance units, the first metal patch unit in the first impedance unit adopts a square ring patch loaded with a spiral inductor, the square ring patch is centrally symmetric about the center point of the dielectric layer, the square ring patch is arranged at the position of the four peripheral edges of the dielectric layer, the square ring patch is loaded with a spiral inductor at the middle position of each edge, the tail end of the spiral inductor wire is connected to the square ring through a bent metal wire, and the center end is connected to the square ring through a metal connecting line on the lower surface of the dielectric layer; the square ring patch is loaded with two first lumped resistors (16) on each edge and located on the two sides of the spiral inductor respectively; The second impedance layer is formed by array arrangement of MxN second impedance units, the second metal patch unit in the second impedance unit is arranged along the x-axis direction, the third metal patch unit is arranged along the y-axis direction, and both adopt the same structure; the metal patch unit is formed by a parallel LC resonant structure and two rectangular patches connected on both sides of the parallel LC resonant structure, a second lumped resistor (17) is loaded between the parallel LC resonant structure and the rectangular patch, and the unit structures are connected through the rectangular patches; the parallel LC resonant structure is formed by a resonant bent inductor wire and a resonant rectangular patch in parallel, a PIN diode (19) is loaded between the rectangular patch and the parallel end respectively, and a lumped capacitor (18) is loaded at the center of the bent inductor wire; the third metal patch unit is translated by P1 / 2 along the x-axis direction and P1 / 2 along the y-axis direction relative to the second metal patch unit, P1 being the unit period of the first and second impedance units; the second metal patch unit is translated by P1 / 2 along the y-axis relative to the first impedance unit. The fourth metal patch layer is composed of 2M*2N fourth metal patch units arranged in an array, the fourth metal patch units are arranged along the x-axis direction, and PIN diodes are loaded between adjacent fourth metal patch units; the fifth metal patch layer is composed of 2M*2N fifth metal patch units arranged in an array, the fifth metal patch units are arranged along the y-axis direction, and PIN diodes are loaded between adjacent fifth metal patch units; the fourth metal patch unit and the fifth metal patch unit have the same structure and are composed of a frequency-selected rectangular patch and a trapezoidal transition patch symmetrically connected on both sides of the frequency-selected rectangular patch; the fifth metal patch unit is translated by P2 / 2 along the x-axis and the y-axis relative to the fourth metal patch unit, P2 is the unit period of the fourth and fifth metal patch units, and P2=P1 / 2; for the fourth metal patch unit and the fifth metal patch unit, every 2*2 subarray corresponds to a first impedance unit, and is translated by P1 / 4 along the x-axis and the -y-axis relative to the first impedance unit; The sixth metal patch layer is composed of 2M*2N sixth metal patch units arranged in an array, the sixth metal patch unit comprises: a frequency-selected bent inductive line and an interdigital capacitor, the two frequency-selected bent inductive lines are cross-shaped and center-symmetric, and the frequency-selected bent inductive lines are respectively connected to the interdigital capacitor, and the interdigital capacitor is shared between adjacent units; the seventh metal patch unit is composed of 2M*2N seventh metal patch units arranged in an array, the seventh metal patch unit adopts a center-symmetric Jerusalem structure composed of a cross-shaped patch and a triangular patch connected to four ends of the cross-shaped patch; for the sixth metal patch unit and the seventh metal patch unit, the unit period is P2, and every 2*2 subarray corresponds to a first impedance unit.

2. The switchable absorption-transmission integrated material with polarization selectivity and high roll-off characteristics according to claim 1, wherein, The values of M and N are not less than 5.

3. The switchable absorption-transmission integrated material with polarization selectivity and high roll-off characteristics according to claim 1, wherein, In the switchable absorption and transmission integrated material, all PIN diodes are used as switching devices, and the working mode switching is divided into four states: Mode 00: all PIN diodes are fully turned off; Mode 01: all PIN diodes in the second metal patch layer and the fourth metal patch layer are turned off; all PIN diodes in the third metal patch layer and the fifth metal patch layer are turned on; Mode 10: all PIN diodes in the second metal patch layer and the fourth metal patch layer are turned on; all PIN diodes in the third metal patch layer and the fifth metal patch layer are turned off; Mode 11: all PIN diodes are fully turned on; In mode 00, the device is in an absorption and transmission integrated working state in the X and Y directions; In mode 11, the device is in an absorber working state in the X and Y directions; In mode 10, the device operates as a polarization selection device, at this time, the in-band X polarized wave is transmitted, and the in-band Y polarized wave is absorbed, realizing polarization selectivity; In mode 01, the device operates as a polarization selection device, at this time, the in-band Y polarized wave is transmitted, and the in-band X polarized wave is absorbed, realizing polarization selectivity.

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