A tunable switchable integrated multifunctional electromagnetic wave absorber

Abstract

This invention proposes a tunable and switchable integrated multifunctional electromagnetic absorber, primarily addressing the problems of existing frequency-selective absorbers, such as single function, fixed operating state, poor switching stability, and narrow tuning and absorption bandwidth. The absorber consists of multiple periodically arranged, switchable and tunable integrated units with identical structures. From top to bottom, each unit comprises an upper switchable loss layer loaded with a PIN diode, a middle tunable loss layer loaded with a varactor diode, and a lower tunable and switchable integrated bandpass frequency selective surface loaded with both a PIN diode and a varactor diode. By introducing switchable and tunable elements, the absorber structure can switch between a transmission state and a pure absorption state, and has a continuously adjustable transmission frequency. Furthermore, the dual-loss layer structure achieves functional decomposition, significantly expanding the absorption bandwidth while maintaining high selective transmission characteristics, high integration, and stable performance.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and further relates to a tunable and switchable integrated absorber in the field of electromagnetic field and microwave technology, which can be used in radar radomes, electromagnetic compatibility, adaptive electromagnetic protection, broadband stealth and intelligent microwave communication systems. Background Technology

[0002] Traditional electromagnetic absorbers are mostly functionally fixed and operate in a single mode, typically only capable of electromagnetic absorption within a fixed frequency band, making them unsuitable for adaptive applications in complex electromagnetic environments. Frequency-tunable absorbers and function-switchable absorbers, as two important types of structures that enhance the flexibility of electromagnetic structures, can respectively achieve dynamic adjustment of the operating frequency band and state switching of electromagnetic operating modes, showing broad application prospects in radar radomes, electromagnetic compatibility, adaptive stealth, and intelligent microwave communication systems.

[0003] However, currently reported and applied electromagnetic absorbers generally suffer from functional limitations: some only possess frequency tunability and cannot switch operating modes; others only achieve functional mode switching but lack frequency tuning capability. Research and structures integrating frequency tunability and functional switching are extremely rare, and no structure yet can switch between wave-transmitting and pure-absorbing states. This makes it difficult to simultaneously achieve continuous frequency tuning and stable mode switching on the same structure, severely limiting the absorber's adaptive operating capability.

[0004] Furthermore, existing switchable absorbers can only achieve simple switching between absorption and reflection, making it difficult to achieve efficient and stable switching from a transparent state to a broadband pure absorption state. Moreover, the transmission frequency is fixed and cannot be tuned. Meanwhile, existing tunable absorbers mostly lack mode switching capabilities and have fixed operating states. Even those few structures that attempt to combine tuning and switching functions have failed to achieve switching from a transparent to a pure absorption state. They generally suffer from low integration, complex structures, narrow tuning ranges, poor switching stability, and the inability to simultaneously achieve high selective transmission and broadband efficient absorption. These limitations fail to meet the comprehensive requirements of tunable, switchable, highly integrated, and high-performance applications in radar radomes, electromagnetic protection, and stealth equipment, thus restricting their promotion and application in practical engineering. Summary of the Invention

[0005] This invention aims to address the shortcomings of existing technologies and fill the gap in the integrated design of tunable and switchable electromagnetic absorbers. It proposes an integrated electromagnetic surface that combines tunability and switchability. This invention addresses the technical problems of existing electromagnetic absorbers, such as the inability to simultaneously achieve continuously tunable operating frequency, stable switching from a transparent state to a broadband pure absorption state, and the inability to maintain stable absorption and transmission performance within the target frequency band, as well as narrow tuning range and absorption bandwidth. It can meet the application requirements of radar radomes, electromagnetic compatibility protection, adaptive broadband stealth, and intelligent microwave communication systems.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A tunable and switchable integrated multifunctional electromagnetic absorber includes multiple tunable and switchable integrated units arranged periodically with the same structure, or is composed only of multiple tunable and switchable integrated units arranged periodically with the same structure; the tunable and switchable integrated unit includes an upper switchable loss layer, a middle tunable loss layer, a lower tunable and switchable integrated bandpass FSS and a DC bias feed structure, or is composed only of an upper switchable loss layer, a middle tunable loss layer, a lower tunable and switchable integrated bandpass FSS and a DC bias feed structure; The upper switchable loss layer is loaded with an upper PIN diode to achieve stable switching of the transmission band and to dissipate electromagnetic waves through an upper loss resistor; the middle tunable loss layer is loaded with a middle varactor diode to achieve tuning of the transmission frequency and to dissipate out-of-band electromagnetic waves through a middle loss resistor; the lower tunable and switchable integrated bandpass FSS is loaded with both a lower PIN diode and a lower varactor diode to achieve both tunability and switchability functions, and has high selectivity. The DC bias feeding structure provides DC bias to the upper PIN diode, the middle varactor diode, the lower PIN diode, and the lower varactor diode. Through the synergistic effect of the upper switchable loss layer, the middle tunable loss layer, the lower tunable and switchable integrated bandpass frequency selective surface, and the DC bias feeding structure, the multifunctional electromagnetic absorber can achieve switching between the wave transmission state and the broadband pure absorption state, as well as continuous tuning of the wave transmission frequency.

[0007] In one embodiment, the upper switchable loss layer has a wide transmission band, which includes an upper metal double helix patch, an upper dielectric substrate, an upper loss resistor, and an upper PIN diode; here, the wide transmission band refers to a continuous frequency range in which the forward transmission coefficient |S21| of the upper switchable loss layer is not less than -1 dB in the transmission state, and the relative bandwidth of the continuous frequency range is not less than 15%.

[0008] Four upper-layer bimetallic spiral patches are printed on the upper surface of the upper dielectric substrate and connected in a square ring via four upper-layer loss resistors. The two spiral structures of each upper-layer bimetallic spiral patch are connected in series and located at the middle of each side of the square ring. Each spiral structure is connected in parallel with an upper-layer PIN diode. For example, the upper-layer loss resistors are applied at the corners of the square ring.

[0009] In one embodiment, the upper switchable loss layer further includes an upper metallized via and an upper metal interconnect, wherein the upper metallized via extends through the upper dielectric substrate, and the upper metal interconnect and the upper PIN diode are printed on the lower surface of the upper dielectric substrate. Each spiral structure is connected in parallel to an upper-layer PIN diode through an upper-layer metallized via and an upper-layer metallized connecting line at both ends. Specifically, the double spiral structure is connected to the upper-layer metallized via penetrating the upper dielectric substrate; the upper-layer metallized connecting line printed on the back of the upper dielectric substrate is connected to the upper-layer metallized via and is connected through the upper-layer PIN diode; there is a circular aperture with the same axis and a radius slightly larger than the metallized via at the upper-layer metallized via; the upper-layer metallized via and the upper-layer metallized connecting line constitute the upper-layer DC power supply network, providing the upper-layer PIN diode with a conduction voltage. Finally, the DC bias power supply structure can provide DC bias to the upper-layer PIN diode through the upper-layer metallized via and the upper-layer metallized connecting line.

[0010] Furthermore, the middle tunable loss layer includes a middle interdigitated metal patch, a middle dielectric substrate, a middle varactor diode, a middle loss resistor, and a metal zigzag connection line; The middle layer interdigitated metal patch consists of four pieces, which are printed on the upper surface of the middle layer dielectric substrate and connected to form a square ring through the middle layer loss resistor. The middle layer varactor diode is embedded in the middle of the interdigitated structure and located in the middle of each side of the square ring, and is connected in parallel with each middle layer varactor diode by a metal zigzag connecting line.

[0011] Furthermore, the intermediate tunable loss layer also includes intermediate metallized vias. The zigzag metal connection lines are printed on the lower surface of the intermediate dielectric substrate and are connected to both ends of the interdigitated structure of an intermediate interdigitated metal patch through the intermediate metallized vias. Specifically, the intermediate interdigitated metal patch is connected to the intermediate metallized vias penetrating the intermediate dielectric substrate; the zigzag metal connection lines are connected to the intermediate metallized vias; the intermediate metallized vias and the zigzag metal connection lines constitute an intermediate DC feed path, providing a bias voltage for the intermediate varactor diode. Ultimately, the DC bias feed structure can provide DC bias to the intermediate varactor diode through the intermediate metallized vias and the zigzag metal connection lines.

[0012] Furthermore, each of the interdigitated metal patches in the middle layer also includes two elongated patches. The two ends of the interdigitated structure are connected to an elongated patch through a middle layer loss resistor, and adjacent interdigitated metal patches in the middle layer are vertically connected through elongated patches.

[0013] In one embodiment, the lower tunable and switchable integrated bandpass FSS includes a lower metal cladding, a lower dielectric substrate, a lower varactor diode, and a lower PIN diode. The lower metal cladding layer includes two concentric square rings printed on the upper surface of the lower dielectric substrate. The sides of the two square rings are connected by lower varactor diodes and lower PIN diodes placed in parallel.

[0014] Furthermore, the four sets of lower-layer varactor diodes and lower-layer PIN diodes are connected between the midpoints of each side of the two square rings, with two metal strips connecting the diagonals in the inner square ring; the lower metal cladding forms a lower-layer DC bias path through the lower metallized vias, which can provide corresponding DC bias for the lower-layer varactor diodes and lower-layer PIN diodes. The DC bias feeding structure provides corresponding DC bias for the lower-layer varactor diodes and lower-layer PIN diodes through the lower metallized vias and the lower metal cladding.

[0015] In one embodiment, the DC bias feeding structure includes interlayer conductive support pillars arranged along the thickness direction of the multifunctional electromagnetic absorber, bias nodes arranged in each functional layer and electrically connected to the corresponding PIN diodes or varactor diodes, radio frequency isolation elements arranged in the DC bias path, and bias metal lines electrically connected to the interlayer conductive support pillars. The bias metal line is electrically connected to the bias node through the interlayer conductive support post, and is used to provide DC bias to the upper PIN diode, the middle varactor diode, the lower PIN diode and the lower varactor diode respectively. The interlayer conductive support post can be one or more of the following: metal post, metal pin, pin header, metallized through hole, conductive screw or conductive rivet, and can also serve as a mechanical support between adjacent layers.

[0016] Furthermore, the interlayer conductive support pillar is arranged along the thickness direction of the multifunctional electromagnetic absorber, with one end electrically connected to the bias metal line or ground metal layer, and the other end electrically connected to the bias node, for realizing DC bias transmission between different functional layers, and at least partially for defining the spacing between adjacent functional layers; the bias node is respectively disposed in the upper switchable loss layer, the middle tunable loss layer, and the lower tunable switchable integrated bandpass FSS, and is electrically connected to the corresponding PIN diode or varactor diode, for introducing DC bias voltage to the corresponding PIN diode or varactor diode; the RF isolation element is disposed in the DC bias path where the bias metal line, interlayer conductive support pillar, or bias node is located, for suppressing RF current from entering the DC bias path. The bias metal line is electrically connected to the interlayer conductive support pillar for transmitting external DC bias voltage.

[0017] Compared with the prior art, the present invention has the following advantages: First, because the frequency selective absorber in this invention incorporates a switchable and tunable element integrated design in the periodic unit, the structure can switch between a wave-transmitting state and a pure wave-absorbing state, and has a continuously adjustable wave-transmitting frequency. Thus, this invention simultaneously possesses both tunable and switchable functions in the same structure, overcoming the problem of single function and fixed working state of the frequency selective absorber in the prior art, and improving the integration of electromagnetic functions and application flexibility.

[0018] Secondly, since the integrated unit in this invention adopts a dual-layer loss structure design with an upper switchable loss layer and a middle tunable loss layer, an effective electromagnetic energy dissipation mechanism is formed in different frequency bands through the synergistic effect of the two loss layers. This overcomes the problems of narrow absorption bandwidth, insufficient absorption efficiency and limited frequency coverage of the single-layer loss structure in the prior art. As a result, this invention has the advantages of significantly expanded broadband pure absorption bandwidth, stable and efficient absorption performance in pure absorption state.

[0019] Third, because this invention achieves continuous and wide tuning range of the transmission frequency through the synergistic control of the middle and lower varactor diodes, combined with the impedance matching design of the double-layer loss layer and the bandpass FSS, it overcomes the problems of fixed operating frequency or limited tuning range of existing absorber structures. It has the advantages of wide tuning range, rapid tuning response, and stable absorption and transmission performance during tuning. This allows the invention to dynamically adjust the operating frequency band according to different application requirements, providing stronger adaptability and spectrum control capabilities in complex electromagnetic environments.

[0020] In addition, the DC bias feeding structure introduces DC bias between different functional layers through interlayer conductive support pillars, and can also serve as interlayer positioning and mechanical support, which is beneficial to improving the assembly stability and bias reliability of the multilayer structure. Attached Figure Description

[0021] Figure 1 This is an exploded view of the overall structure and the tunable and switchable integrated multifunctional electromagnetic wave absorber of the present invention. Figure 2(a) is an exploded view of the upper switchable loss layer unit structure of the present invention; Figure 2(b) is a top view, a bottom view and a side view of the upper switchable loss layer unit of the present invention; Figure 3(a) is an exploded view of the middle layer tunable loss layer unit structure of the present invention; Figure 3(b) is a top view, a bottom view and a side view of the middle layer tunable loss layer unit of the present invention; Figure 4(a) is an exploded view of the lower-layer tunable and switchable bandpass FSS structure of the present invention; Figure 4(b) is a top view and a side view of the lower-layer tunable and switchable bandpass FSS of the present invention; Figure 5 This is a schematic diagram of the DC bias feeding structure and the interlayer conductive support column in an embodiment of the present invention; Figure 6 This is a waveform transmission coefficient curve from a simulation experiment of an embodiment of the present invention; Figure 7 This is a graph showing the reflection coefficient and absorption rate curves in a simulation experiment according to an embodiment of the present invention; Detailed Implementation The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The accompanying drawings mainly show the schematic layout of the core functional layer of the absorber, the metal patch, the PIN diode, the varactor diode, and part of the DC bias structure of the present invention; for the sake of simplifying the view, some bias metal lines, interlayer conductive support pillars and radio frequency isolation elements may be omitted in the drawings or shown in schematic form, and their specific positions and connection methods can be adaptively set according to the bias nodes in each functional layer.

[0022] Reference Figures 1-5 The overall structure of the multifunctional electromagnetic wave absorber of the present invention will be described in further detail below.

[0023] The tunable and switchable integrated multifunctional electromagnetic absorber of this invention is mainly composed of multiple tunable and switchable integrated units 1 arranged periodically with the same structure. The tunable and switchable integrated unit 1 is mainly composed of an upper switchable loss layer 11, a middle tunable loss layer 12, a lower tunable and switchable integrated bandpass FSS 13, and a DC bias feeding structure 14 cascaded or combined.

[0024] The upper switchable loss layer 11 has a wide transmission band. Electromagnetic waves are dissipated through the upper loss resistor 113, and an upper PIN diode 114 is loaded, enabling stable switching of the transmission band. The middle tunable loss layer 12, through the loading of a middle varactor diode 123, enables continuous tuning of the transmission frequency, and electromagnetic waves are dissipated through a middle loss resistor 124. The lower tunable and switchable integrated bandpass FSS 13 simultaneously loads a PIN diode and a varactor diode, thus achieving both tunability and switchability functions with high selectivity. The cascaded three-layer structure enables stable switching from a transmission state to a broadband pure absorption state, and the transmission frequency can be continuously tuned within a wide bandwidth.

[0025] The multifunctional electromagnetic absorber of the present invention, through the synergistic effect of the upper switchable loss layer 11, the middle tunable loss layer 12, the lower tunable and switchable integrated bandpass FSS 13 and the DC bias feeding structure 14, can achieve switching between the wave transmission state and the broadband pure wave absorption state, and can achieve continuous tuning of the wave transmission frequency.

[0026] Referring to Figures 2(a) and 2(b), the upper switchable loss layer unit 11 is a double-helix metal patch structure with a PIN diode loaded, and the unit size is... w × l =20mm×20mm, mainly including upper metal double spiral patch 111, upper dielectric substrate 112, upper loss resistor 113 (i.e., each R1 in the figure), upper PIN diode 114, upper metallized via 115, and upper metal interconnect 116. Among them, the upper metal spiral patch 111 consists of four identical pieces with a length of 10mm×20mm. l The 0=15mm double helix structure is connected by four upper-layer loss resistors 113, and the distance between the relative metal helical structures is... w 0 = 16.2mm, other structural parameters are: width w 1=1.2mm, spiral gap width s =0.2mm, spiral width w m =0.2mm, loss resistance R 1=270 ohm A multifunctional electromagnetic wave absorber is printed on the upper surface of the upper dielectric substrate 112, and has a radius of [missing information] penetrating the upper dielectric substrate 112. r The upper metallized through-hole 115 with a diameter of 0=0.2mm is connected; the width is w nA 0.2mm thick upper-layer metal interconnect 116 is printed on the back side of the upper dielectric substrate 112, connected to the upper-layer metallized via 115, and connected via upper-layer PIN diodes 114. Each upper-layer PIN diode 114 is connected in parallel with a spiral structure. The upper-layer PIN diodes 114 are equivalently represented using a series RLC lumped parameter model, with the following parameters: L s =0.7nH、 C off =0.118pF R on =1.5 ohm; the upper dielectric substrate 112 uses a thickness of h 1 = 0.508 mm, dielectric constant is ε r =2.2, a dielectric substrate with a loss tangent of tanδ=0.0009.

[0027] Referring further to Figures 3(a) and 3(b), the middle tunable loss layer 12 is an interdigitated structure with varactor diodes loaded, and the unit size is... w 12 × l 12 =20mm×20mm, including a middle layer interdigitated metal patch 121, a middle layer dielectric substrate 122, a middle layer varactor diode 123, a middle layer loss resistor 124 (i.e., each R2 in the figure), a middle layer metallized via 125, and a metal bend connecting line 126. The middle layer interdigitated metal patch 121 consists of four identical patches with a length of... l 13 The interdigitated structure has a diameter of 16.5mm. Each end of the interdigitated structure is connected to a strip-shaped patch via a middle-layer loss resistor (124). Adjacent strip-shaped patches are vertically connected, ultimately forming a square ring structure. The distance between opposing interdigitated structures is... w 13 =14.1mm, other structural parameters are: width w 2 = 1.2mm, interdigitated gap width s 1=0.2mm, interdigitated strip width w 14 =0.15mm, interdigitated strip length l m =1.5mm, loss resistance R 2 = 180 ohms, printed on the upper surface of the middle layer dielectric substrate 122, with a radius of [missing information - likely a value] penetrating the dielectric substrate 122. r A 0.2mm middle-layer metallized via 125 is connected; four middle-layer varactor diodes 123 are respectively embedded in the middle of the four interdigitated structures, with a length of... l b=1.7mm, represented by the equivalent capacitance model C1; the middle layer metal bend connecting line 126 is printed on the lower surface of the middle layer dielectric substrate 122 and connected to the middle layer metallized via 125. Specific parameters are: strip width w 15 =0.12mm, strip gap width s 2 = 0.2 mm; the middle layer dielectric substrate 122 uses a thickness of h 2 = 0.254 mm, dielectric constant is ε r =2.2, a dielectric substrate with a loss tangent of tanδ=0.0009.

[0028] Referring to Figures 4(a) and 4(b), the cell size of the lower-layer tunable and switchable integrated bandpass FSS13 is... w 21 × l 21 =20mm×20mm, including a lower metal cladding layer 131, a lower dielectric substrate 132, a lower varactor diode 133, and a lower PIN diode 134. The lower metal cladding layer 131 includes an outer square metal ring and an inner square metal ring with a central cross-shaped connection structure. Specific structural parameters are as follows: square gap size... w 22 = l 22 =7.5mm, cross-shaped structure dimensions w 23 = l 23 =3mm, width s 2 = 0.2 mm, printed on the upper surface of the lower dielectric substrate 132; the length is... d The lower-layer varactor diode 133 and lower-layer PIN diode 134, with a thickness of 0.6mm, are used to connect the inner and outer square metal rings and are placed in reverse parallel. They can operate independently. The lower-layer PIN diode 134 is represented using a lumped parameter circuit, which is completely consistent with the upper-layer PIN diode 114. The lower-layer varactor diode 133 is represented using the equivalent capacitance model C2. The lower-layer dielectric substrate 132 has a thickness of... h 3 = 2mm, dielectric constant is ε r =2.2, a dielectric substrate with a loss tangent of tanδ=0.0009.

[0029] Further reference Figure 5The DC bias feed structure 14 includes interlayer conductive support pillars 141, bias nodes 142, RF isolation elements 143, and bias metal lines 144. The bias metal lines 144 are used to connect to an external DC bias power supply and introduce DC bias voltage into the corresponding functional layer through the interlayer conductive support pillars 141, namely one or more of the upper switchable loss layer 11, the middle tunable loss layer 12, and the lower tunable and switchable integrated bandpass FSS 13. The interlayer conductive support pillars 141 are arranged along the thickness direction of the absorber, with one end electrically connected to the bias metal lines 144 or connected to a grounded metal layer, and the other end electrically connected to the bias nodes 142 in the corresponding functional layer. Bias node 142 is disposed in the upper switchable loss layer 11, the middle tunable loss layer 12, and / or the lower tunable switchable integrated bandpass FSS 13, and is electrically connected to the corresponding upper PIN diode 114, middle varactor diode 123, lower PIN diode 134, or lower varactor diode 133, thereby providing the required DC bias for each switchable and tunable element. RF isolation element 143 is disposed in the DC bias path where the bias metal line 144, interlayer conductive support pillar 141, or bias node 142 is located, to suppress RF current from entering the DC bias path and reduce the impact of the DC bias feed structure 14 on the RF response of the absorber. Specifically, the upper metallized via 115, the upper metal connection line 116, and / or the interlayer conductive support pillar constitute the upper DC bias path, providing DC bias for the upper PIN diode 114. The middle layer metallized via 125, the metal bend connecting line 126, and / or the interlayer conductive support pillar constitute a middle layer DC bias path, providing DC bias for the middle layer varactor diode 123. The lower layer metal cladding 131 constitutes a lower layer DC bias path through the lower layer metallized via, the bias metal line, and / or the interlayer conductive support pillar, providing corresponding DC bias for the lower layer varactor diode 133 and the lower layer PIN diode 134, respectively.

[0030] In this embodiment of the invention, the radio frequency isolation element 143 can be a radio frequency inductor, an isolation resistor, a high-impedance microstrip line, a tortuous metal line, a choke stub, or a combination thereof. The interlayer conductive support pillar 141 can be one or more of a metal pillar, a metal pin, a pin header, a metallized through-hole, a conductive screw, or a conductive rivet, and can simultaneously serve as a support structure between adjacent dielectric substrates to define the interlayer spacing and improve the assembly stability of the multilayer structure.

[0031] The technical effects of the present invention will be further explained below with reference to simulation experiments: The result curves obtained by modeling and simulating the embodiments of the present invention using the commercial electromagnetic simulation software Ansys HFSS 2024 are shown below. Figure 6 and Figure 7 As shown. Figure 6This represents |S|, which reflects the tuning performance of the absorber. 21 The parameter curve has the horizontal axis representing the frequency value in GHz and the vertical axis representing the S-parameters in dB. Figure 7 This represents the S-parameters and absorption rate curves that reflect the pure absorption performance of the absorber. Figure 7 The solid black line in the middle represents the |S| when the absorber switches to pure absorption mode. 11 The curve, in dB, shows the absorption rate when the absorber switches to pure absorption mode. It can be seen that this embodiment of the invention possesses both tunable and switchable functions, allowing switching between broadband tuning and pure absorption modes. Figure 6 It can be seen that the structure can be continuously tuned in the range of 4.19~5.15 GHz, with a tuning bandwidth of 0.96 GHz, and the forward transmission coefficient |S| within this range is also high. 21 | It remains within the range of -1 to 0 dB, with a variation range of within 1 dB. Figure 7 As can be seen, this invention exhibits broadband absorption characteristics in the 2.04~11.55 GHz range, with a reflection coefficient |S 11 The absorption rate is below -10 dB, the absorption efficiency is above 90%, and the relative absorption bandwidth can reach 139.9%. In summary, the absorber structure of this invention has two stable and independent operating states: tunable and switchable, which can realize the switching from broadband tunable state to broadband pure absorption state.

[0032] Although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A tunable and switchable integrated multifunctional electromagnetic wave absorber, characterized in that, It includes multiple tunable and switchable integrated units (1) arranged in a periodic manner with the same structure; the tunable and switchable integrated unit (1) includes an upper switchable loss layer (11), a middle tunable loss layer (12), a lower tunable and switchable integrated bandpass FSS (13) and a DC bias feed structure (14). The upper switchable loss layer (11) is loaded with an upper PIN diode (114) to achieve stable switching of the transmission band and to dissipate electromagnetic waves through an upper loss resistor (113); the middle tunable loss layer (12) is loaded with a middle varactor diode (123) to achieve tuning of the transmission frequency and to dissipate out-of-band electromagnetic waves through a middle loss resistor (124); the lower tunable and switchable integrated bandpass FSS (13) is loaded with both a lower PIN diode (134) and a lower varactor diode (133) to achieve both tunability and switchability. The DC bias feeding structure (14) provides DC bias to the upper PIN diode (114), the middle varactor diode (123), the lower PIN diode (134), and the lower varactor diode (133), thereby coordinating the switching between the wave transmission state and the broadband pure absorption state, as well as the continuous tuning of the wave transmission frequency.

2. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 1, characterized in that, The upper switchable loss layer (11) includes an upper metal double helix patch (111), an upper dielectric substrate (112), an upper loss resistor (113), and an upper PIN diode (114). There are four upper bimetallic spiral patches (111), which are printed on the upper dielectric substrate (112) and connected to form a square ring through four upper loss resistors (113). The two spiral structures of each upper bimetallic spiral patch (111) are connected in series and located in the middle of each side of the square ring. Each spiral structure is connected in parallel with an upper PIN diode (114).

3. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 2, characterized in that, The upper switchable loss layer (11) also includes an upper metallized via (115) and an upper metal interconnect (116). The upper metallized via (115) is disposed through the upper dielectric substrate (112), and the upper metal interconnect (116) and the upper PIN diode (114) are printed on the lower surface of the upper dielectric substrate (112). Each spiral structure is connected in parallel with an upper PIN diode (114) through an upper metallized via (115) and an upper metal connecting line (116). The DC bias feeding structure (14) provides DC bias to the upper PIN diode (114) through the upper metallized via (115) and the upper metal connecting line (116).

4. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 1, characterized in that, The middle tunable loss layer (12) includes a middle interdigitated metal patch (121), a middle dielectric substrate (122), a middle varactor diode (123), a middle loss resistor (124), and a metal zigzag connection line (126). Four interdigitated metal patches (121) are printed on the upper surface of the intermediate dielectric substrate (122) and connected to form a square ring through the intermediate loss resistor (124). The intermediate varactor diode (123) is embedded in the middle of the interdigitated structure and located in the middle of each side of the square ring. A metal zigzag connection line (126) is provided in parallel with each intermediate varactor diode (123).

5. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 4, characterized in that, The intermediate tunable loss layer (12) also includes an intermediate metallized via (125). The metal zigzag connection line (126) is printed on the lower surface of the intermediate dielectric substrate (122) and is connected to the two ends of the interdigitated structure of an intermediate interdigitated metal patch (121) through the intermediate metallized via (125). The DC bias feed structure (14) provides DC bias to the intermediate varactor diode (123) through the intermediate metallized via (125) and the metal zigzag connection line (126).

6. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 4, characterized in that, Each interdigitated metal patch (121) further includes two strip patches. The two ends of the interdigitated structure are connected to a strip patch through an intermediate loss resistor (124). Adjacent interdigitated metal patches (121) are vertically connected through strip patches.

7. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 1, characterized in that, The lower-layer tunable and switchable integrated bandpass FSS (13) includes a lower-layer metal cladding (131), a lower-layer dielectric substrate (132), a lower-layer varactor diode (133), and a lower-layer PIN diode (134). The lower metal cladding (131) includes two concentric square rings printed on the upper surface of the lower dielectric substrate (132). The sides of the two square rings are connected by a lower varactor diode (133) and a lower PIN diode (134) placed in parallel.

8. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 7, characterized in that, The four sets of lower varactor diodes (133) and lower PIN diodes (134) are connected between the midpoints of the two sides of the square rings, with metal strips connecting the diagonals in the inner square rings; the DC bias feed structure (14) provides corresponding DC bias to the lower varactor diodes (133) and lower PIN diodes (134) through the lower metallized vias and the lower metal cladding (131).

9. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 1, characterized in that, The DC bias feeding structure (14) includes an interlayer conductive support column (141) arranged along the thickness direction of the multifunctional electromagnetic absorber, a bias node (142) arranged in each functional layer and electrically connected to the corresponding PIN diode or varactor diode, a radio frequency isolation element (143) arranged in the DC bias path, and a bias metal line (144) electrically connected to the interlayer conductive support column (141). The bias metal line (144) is electrically connected to the bias node (142) through the interlayer conductive support pillar (141) and is used to provide DC bias to the upper PIN diode (114), the middle varactor diode (123), the lower PIN diode (134) and the lower varactor diode (133) respectively. The interlayer conductive support pillar (141) also serves as a mechanical support between adjacent layers.

10. The tunable and switchable integrated multifunctional electromagnetic wave absorber according to claim 9, characterized in that, The interlayer conductive support pillar (141) is arranged along the thickness direction of the multifunctional electromagnetic absorber. One end of the pillar is electrically connected to the bias metal line (144) or the ground metal layer, and the other end is electrically connected to the bias node (142). The bias node (142) is respectively arranged in the upper switchable loss layer (11), the middle tunable loss layer (12), and the lower tunable switchable integrated bandpass FSS (13) to introduce DC bias to the corresponding PIN diode or varactor diode. The radio frequency isolation element (143) is arranged in the DC bias path where the bias metal line (144), the interlayer conductive support pillar (141), or the bias node (142) is located to suppress radio frequency current from entering the DC bias path. The interlayer conductive support pillar (141) is one or more of the following: metal pillar, metal pin, pin header, metallized through hole, conductive screw, or conductive rivet.

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