A system for adjusting a frequency selective absorber

Abstract

An embodiment of the present invention discloses a system for adjusting a frequency-selective absorber, relating to the field of stealth technology. This system enables the frequency-selective absorber to switch its operating mode, thereby achieving tunable performance in its frequency band, and has broader application prospects. The present invention includes: a host computer connected to both a temperature sensor and a water pump device, the water pump device being mounted on the frequency-selective absorber; the water pump device being connected to the water channel and liquid storage tank of the frequency-selective absorber. The temperature sensor is used to collect temperature information and transmit it to the host computer; the host computer is used to determine whether to perform liquid exchange based on the temperature information, and if so, trigger the water pump device to operate, thereby extracting or refilling the liquid in the frequency-selective absorber.

Description

Technical Field

[0001] The present invention relates to the field of stealth technology, and in particular to a system for adjusting a frequency selective absorber. Background Art

[0002] As the forefront of detection and guidance, radar antennas must ensure the proper transmission and reception of electromagnetic waves. They cannot directly achieve stealth through external stealth techniques or coatings with radar-absorbing materials. Currently, the most widely adopted stealth technology is frequency-selective surfaces (FSS), but its stealth performance against multi-base radars remains limited. Furthermore, FSS-designed radomes are often conformally attached to the radome, reducing backscatter but increasing the RCS in other directions, limiting their stealth effectiveness. To improve stealth performance, the concept of electromagnetic metamaterial absorbers has been introduced into radome design, creating absorbers with frequency-selective properties. Research on electromagnetic metamaterial frequency-selective absorbers is a key focus within this field. Current frequency-selective absorbers are often based on complex multi-layer structures such as resistor components or high-resistance surfaces, achieving integrated transmission / reflection designs. Traditional reconfigurable frequency-selective absorbers are primarily based on functional materials such as pin diodes, varactor diodes, and vanadium dioxide, or micro-electromechanical systems (MEMS). However, these materials present challenges such as high cost, difficult processing, and frequency offset.

[0003] Therefore, it is necessary to continue to optimize the structural design and realize the tunable performance of the frequency band of the frequency selective absorber, so that it will have real practical value. Summary of the Invention

[0004] The embodiments of the present invention provide a system for adjusting a frequency selective absorber, which enables the switchable working mode of the frequency selective absorber, thereby achieving the function of tunable performance of its frequency band, and has broader application prospects.

[0005] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0006] A system for adjusting a frequency selective absorber, the system comprising: a host computer (1), a temperature sensor (2), a water pump device, a frequency selective absorber (4) and a liquid storage tank (5);

[0007] The host computer (1) is connected to the temperature sensor (2) and the water pump device at the same time, and the water pump device is installed on the frequency selective absorber (4);

[0008] The water pump device comprises a first water pump (3-1) for pumping water and a second water pump (3-2) for injecting water, wherein the water inlet of the first water pump (3-1) is communicated with a water channel (4-4) of a frequency selective wave absorbing body (4), the water outlet of the first water pump (3-1) is communicated with a liquid storage tank (5), the water outlet of the second water pump (3-2) is communicated with the water channel (4-4) of the frequency selective wave absorbing body (4), and the water inlet of the second water pump (3-2) is communicated with the liquid storage tank (5);

[0009] The temperature sensor (2) is used to collect temperature information and send it to the host computer (1);

[0010] The upper computer (1) is used to determine whether to perform liquid exchange based on the temperature information, and if so, trigger the water pump device to operate;

[0011] The second water pump (3-2) is used to pump the liquid out of the frequency selective absorber (4) and input the liquid into the liquid storage tank (5);

[0012] The second water pump (3-2) is used to inject the liquid in the liquid storage tank (5) into the frequency selective absorber (4).

[0013] The system for adjusting a frequency-selective absorber provided in this embodiment provides a fully tunable, all-dielectric frequency-selective absorber and achieves switchable operating modes. The liquid can be water doped with propylene glycol to enhance its wave and energy absorption. Compared to traditional structures, this system offers significant cost savings, ease of preparation, and a simple structure, while uniquely achieving frequency-band tunability. Specifically, it utilizes the reflective properties of the liquid to control the pumping of water into and out of the water channel, thereby enabling switching of the operating mode from a frequency-selective absorber to a band-trapped absorber. This allows for switchable operating modes and thus achieves frequency-band tunability, promising broader application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0015] Figures 1a to 1f It is a structural schematic diagram of one unit of the frequency selective absorber provided by the present invention.

[0016] Figure 2 It is a schematic diagram of the overall structure of the frequency selective absorber provided by the present invention.

[0017] Figure 3Schematic diagram of the architecture of the system for adjusting the frequency selective absorber provided by the present invention.

[0018] Figure 4 It is a schematic diagram of the internal structure of the frequency selective absorber provided by the present invention.

[0019] Figure 5 It is a program flow chart of the embedded control system of the present invention.

[0020] Figure 6 This is a transmission / reflection curve of the water-based broadband switchable water-based frequency selective absorber of the present invention in the frequency selective absorber mode.

[0021] Figure 7 This is a reflection curve of the broadband switchable water-based frequency selective absorber in the band-trapped absorber mode of the present invention. DETAILED DESCRIPTION

[0022] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention will be described in detail below, with examples of the embodiments illustrated in the accompanying drawings. Throughout, identical or similar reference numerals represent identical or similar elements or elements having identical or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and intended only to explain the present invention and are not to be construed as limiting the present invention. Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a," "an," "said," and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" as used in the description of the present invention refers to the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or intervening elements may be present. Furthermore, "connected" or "coupled" as used herein may include wireless connections or couplings. The term "and / or" as used herein includes any and all combinations of one or more associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless defined as such herein.

[0023] The embodiment of the present invention provides a system for adjusting a frequency selective absorber, such as Figure 3 As shown, the system comprises: a host computer (1), a temperature sensor (2), a water pump device, a frequency selective absorber (4) and a liquid storage tank (5).

[0024] The host computer (1) is connected to the temperature sensor (2) and the water pump device, and the water pump device is installed on the frequency selective absorber (4). In practical applications, from the hardware level, the host computer (1) can adopt a traditional single-chip microcomputer or an FPGA (Field Programmable Gate Array). The program for the water pump device is stored in the host computer (1), that is, the host computer (1) can be understood as a single-chip microcomputer or FPGA with a control program recorded.

[0025] like Figure 3 As shown, the water pump device includes a first water pump (3-1) for pumping water and a second water pump (3-2) for injecting water, the water inlet of the first water pump (3-1) is connected to the water channel (4-4) of the frequency selective absorber (4), the water outlet of the first water pump (3-1) is connected to the liquid storage tank (5), the water outlet of the second water pump (3-2) is connected to the water channel (4-4) of the frequency selective absorber (4), and the water inlet of the second water pump (3-2) is connected to the liquid storage tank (5).

[0026] The temperature sensor (2) is used to collect temperature information and send it to the host computer (1).

[0027] The host computer (1) is used to determine whether to perform liquid exchange based on the temperature information, and if so, trigger the water pump device to operate. The first water pump (3-1) is used to extract the liquid in the frequency selective absorber (4) and input it into the liquid storage tank (5). The second water pump (3-2) is used to inject the liquid in the liquid storage tank (5) into the frequency selective absorber (4).

[0028] In practical applications, the first water pump (3-1) can be used to pump out liquid while the second water pump (3-2) is turned off, thereby forming a state in which the frequency selective absorber (4) is evacuated; or the first water pump (3-1) can be turned off while the second water pump (3-2) is turned on until the frequency selective absorber (4) is filled, thereby forming a state in which the frequency selective absorber (4) is filled. In this way, the reflection characteristics of the liquid are utilized to control the pumping in and out of the water channel, thereby presenting a switching of the working mode from the frequency selective absorber to the band-trapped absorber, realizing the switchable working mode (liquid evacuation / liquid filling) of the frequency selective absorber, thereby realizing the function of the tunable performance of its frequency band.

[0029] Furthermore, in actual applications, when the frequency selective absorber is irradiated by electromagnetic waves and absorbs electromagnetic waves, the temperature will rise. When the temperature rise is detected, the liquid in the truncated cone structure needs to be replaced. The reason is that: on the one hand, the temperature change will affect the electromagnetic properties of liquids such as propylene glycol aqueous solution, and replacement is required to maintain stable wave absorbing performance; on the other hand, the temperature rise will increase the evaporation of the liquid, and heat dissipation is required. The method of replacing the liquid in the truncated cone structure is to use the first water pump (3-1) to extract the liquid in the frequency selective absorber (4) and use the second water pump (3-2) to inject the liquid in the liquid storage tank (5) into the frequency selective absorber (4). That is, the first water pump (3-1) is used to extract the liquid, and the second water pump (3-2) is used to inject the liquid, forming a liquid circulation between the frequency selective absorber (4) and the liquid storage tank (5), thereby playing a role in heat dissipation.

[0030] In general, in this embodiment, the operation of the two water pumps is controlled by the host computer, which not only realizes the tunable performance of the frequency band of the frequency selective absorber, but also facilitates heat dissipation, thus killing two birds with one stone.

[0031] Specifically, in this embodiment, an embedded control system may be used to execute a program running on the system for adjusting the frequency selective absorber, for example Figure 5 As shown, it includes two functions: temperature acquisition and water pump driving. Under the control of this system, the functional body completes the switching of functional modes.

[0032] The water channel fits tightly with the closed structure formed by structures (4-2) and (4-3) to form a closed water channel, thereby forming a closed structure, and the liquid is filled in the closed structure. The overall structural design realizes the switching of the working mode from a frequency selective absorber to a trap-type absorber, while meeting good impedance matching. The water in the water channel can be flexibly pumped in and out by a water pump controlled by an embedded system. When receiving the corresponding command, the water pump performs the corresponding pumping in and out operation, and the main body realizes the switching of the functional mode, for example Figure 5 The embedded control system's program flow chart includes two functions: temperature acquisition and water pump driving. Under the control of this system, the main functional body switches between functional modes. Due to the unique electromagnetic properties of water, when water is pumped out, the frequency-selective absorber exhibits a wide absorption band and low insertion loss transmission passband. When the water channel is filled with water, the broadband switchable frequency-selective absorber exhibits the characteristics of a band-trapped absorber with a wide absorption band and high reflection efficiency, making it more suitable for "intelligent" stealth systems.

[0033] Specifically, the frequency selective absorber is composed of unit structures arranged in an array, such as Figure 1a to Figure 1fAs shown, each unit structure includes: a parallel plate waveguide structure (4-1), a reflective frequency selective surface (4-2), a container (4-3) and a water channel (4-4), wherein the parallel plate waveguide structure (4-1) is composed of three mutually parallel PCB boards, including an upper PCB board (4-1-1), a lower PCB board (4-1-2) and a middle PCB board (4-1-3), and the main body of each PCB board is a dielectric substrate and the upper and lower surfaces of the dielectric substrate are covered with a copper layer.

[0034] Specifically, the dielectric substrate and the reflective frequency selective surface (4-2) of each PCB board are made of F4BM220 dielectric material with a relative dielectric constant of 2.20 and a loss tangent of 0.001.

[0035] The container (4-3) is mounted on the container base (4-3-1). The cavity formed by the container base (4-3-1) and the U-shaped groove structure (4-4-1) serves as a water channel (4-4). The container base (4-3-1) is in contact with the lower surface of the upper PCB (4-1-1) and the upper surface of the middle PCB (4-1-3). The reflective frequency selective surface (4-2) is parallel to the water channel (4-4).

[0036] Further Figure 1c As shown, the upper PCB board (4-1-1) is composed of three layers, including: a first dielectric substrate (4-1-1-1), an upper PCB board copper clad layer (4-1-1-2) covering the upper layer of the first dielectric substrate (4-1-1-1), and an upper PCB board lower copper clad layer (4-1-1-3) covering the lower layer of the first dielectric substrate (4-1-1-1). Figure 1b 、 Figure 1d As shown, the lower PCB board (4-1-2) is also composed of three layers, including: a second dielectric substrate (4-1-2-1), a lower PCB board copper clad layer (4-1-2-2) covering the upper layer of the second dielectric substrate (4-1-2-1), and a lower PCB board lower copper clad layer (4-1-2-3) covering the lower layer of the second dielectric substrate (4-1-2-1). Figure 1d As shown, a plurality of holes can also be opened in the second dielectric substrate (4-1-2-1), one of which is a metallized via hole, for example Figure 1e As shown, a metalized via hole (4-1-2-1-1) and the remaining multiple non-metalized via holes (4-1-2-1-2) are opened. It should be noted that Figure 1b 、 Figure 1eThe cylinder marked with the number (4-1-2-1-1) is to indicate that it is a metalized via hole, which is equivalent to the inner diameter surface of the hole being covered with a metal layer. If this metal side is peeled off separately, it will appear cylindrical. The "cylinder" in the figure is used to represent the metal layer covering the inner diameter surface of the hole. Figure 1a 、 1b In the figure, this “cylinder” is shown above the second dielectric substrate (4-1-2-1), and in the attached Figure 1d 、 1e The “cylinder” is shown below the second dielectric substrate (4-1-2-1) in order to clearly show the metallized via (4-1-2-1-1), rather than the existence of a solid cylindrical structure above or below the second dielectric substrate (4-1-2-1).

[0037] Further, such as Figure 4 As shown, the length l of the three parallel PCB boards b1 The thickness of the upper PCB board (4-1-1) and the lower PCB board (4-1-2) are both h b2 =1mm, the thickness of the middle PCB (4-1-3) h b1 =2mm. The center of the middle PCB (4-1-3) is opened with a diameter D v The metalized via is 2.6mm.

[0038] The container (4-3) is a truncated cone, and the container base (4-3-1) is a rectangular parallelepiped with at least two square faces, each side of which is 10 mm. The maximum thickness of the container base (4-3-1) is h1 = 4.3 mm, and the thickness of the interior space of the container base (4-3-1) is h4 = 2.3 mm. The interior space of the container (4-3) is equipped with an upright water pipe, the height of which is h2 = 9.8 mm, and the diameter is r a3 = 2mm, the height of the internal space of the container (4-3) is h3 = 8mm, and the maximum distance between the outer surface of the water pipe and the inner wall of the container (4-3) is l b3 =4mm. The outer diameter r of the upper surface of the container (4-3) a1 =4mm, inner diameter r of the upper surface of container (4-3) a2 =3mm, inner diameter r of the lower surface of container (4-3) a4 =8mm, outer diameter r of the lower surface of container (4-3) a5 =9.5mm.

[0039] The reflective frequency selective surface (4-2) is attached with a meandering metal line. The length and width P and h of the reflective frequency selective surface (4-2) are a The width of the meandering metal line is 10 mm and the thickness d is 0.5 mm.t is 0.3 mm, and the width of the head of the meandering metal wire is l t =2.5mm, the maximum width of the pattern formed by the meandering metal wire is l m =7.1mm, the middle part of the pattern formed by the meandering metal wire is broken and the width of the break is g=0.2mm, and the distance between any two parallel lines in the pattern formed by the meandering metal wire is gm=0.7mm.

[0040] The length P, width h6 and thickness l of the U-shaped channel structure (4-4-1) c1 The depth of the groove of the U-shaped groove structure (4-4-1) is 10mm, 14mm and 3mm respectively. c3 and the length of the groove l c2 2mm and 12mm respectively.

[0041] In the preferred embodiment of the present invention, the liquid storage tank (5) is filled with a propylene glycol aqueous solution with a volume concentration of 50%.

[0042] In practical applications, such as Figure 6 As shown in FIG. 1 , the electromagnetic parameter curve of the frequency selective absorber mode of the structure designed in the present invention is shown. The frequency band of S11 below -10 dB is 2.54 to 18.0 GHz, the frequency band of the transmission window with an insertion loss less than 3 dB is 5.43 to 6.42 GHz, and the minimum insertion loss is 0.91 dB. Figure 7 The electromagnetic parameter curves of the structure of the present invention in the band-debye absorber mode are shown. The frequency range where S11 is below -10dB is 2.56-17.3GHz, the frequency range where S11 is greater than -3dB is 5.54-6.16GHz, the center frequency is 5.86GHz, and the maximum S11 is -0.93dB. The water (Debye mode 1) used here operates at room temperature (20°C) and standard atmospheric pressure.

[0043] The liquid used in this embodiment is not limited to propylene glycol; other liquids, such as ethanol-water solutions, or other high-loss solutions can be used. The dielectric substrate can use low-loss materials such as Rogers 5880 or a low-relative-permittivity dielectric. The container and water channel do not necessarily need to be made of resin; materials such as ABS, nylon, or fiberglass can also be used, as long as the relative permittivity and thickness provide good impedance matching.

[0044] The advantage of this embodiment is that it provides a fully dielectric, tunable frequency-selective absorber. The liquid can be water doped with propylene glycol to enhance its absorption and energy absorption. Compared to traditional structures, this design offers significant cost savings, ease of preparation, and structural simplicity, while uniquely achieving frequency-band tunability. Specifically, it utilizes the reflective properties of the liquid to control the flow of water into and out of the water channel, enabling switching between frequency-selective and band-trapped absorber modes, further aligning with the "intelligent" nature of stealth systems.

[0045] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited to this. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A system for adjusting a frequency selective absorber, characterized in that: The system comprises: a host computer (1), a temperature sensor (2), a water pump device, a frequency selective absorber (4) and a liquid storage tank (5); The host computer (1) is connected to the temperature sensor (2) and the water pump device at the same time, and the water pump device is installed on the frequency selective absorber (4); The water pump device includes a first water pump (3-1) for pumping water and a second water pump (3-2) for injecting water, wherein the water inlet of the first water pump (3-1) is connected to the water channel (4-4) of the frequency selective absorber (4), the water outlet of the first water pump (3-1) is connected to the liquid storage tank (5), the water outlet of the second water pump (3-2) is connected to the water channel (4-4) of the frequency selective absorber (4), and the water inlet of the second water pump (3-2) is connected to the liquid storage tank (5); The temperature sensor (2) is used to collect temperature information and send it to the host computer (1); The upper computer (1) is used to determine whether to perform liquid exchange based on the temperature information, and if so, trigger the water pump device to operate; The first water pump (3-1) is used to pump liquid out of the frequency selective absorber (4) and input the liquid into the liquid storage tank (5); The second water pump (3-2) is used to inject the liquid in the liquid storage tank (5) into the frequency selective absorber (4).

2. The system for adjusting a frequency selective absorber according to claim 1, wherein: The frequency selective absorber is composed of a unit structure arranged in an array: Each unit structure includes: a parallel plate waveguide structure (4-1), a reflective frequency selective surface (4-2), a container (4-3) and a water channel (4-4), wherein the parallel plate waveguide structure (4-1) is composed of three mutually parallel PCB boards, including an upper PCB board (4-1-1), a lower PCB board (4-1-2) and a middle PCB board (4-1-3), and the main body of each PCB board is a dielectric substrate and the upper and lower surfaces of the dielectric substrate are covered with a copper layer.

3. The system for adjusting a frequency selective absorber according to claim 1, wherein: The container (4-3) is installed on the container base (4-3-1), and the cavity formed by the container base (4-3-1) and the U-shaped groove structure (4-4-1) serves as a water channel (4-4). The container base (4-3-1) is in contact with the lower surface of the upper PCB board (4-1-1) and the upper surface of the middle PCB board (4-1-3). The reflective frequency selective surface (4-2) is parallel to the water channel (4-4).

4. The system for adjusting a frequency selective absorber according to claim 2 or 3, characterized in that: The length l of three parallel PCB boards b1 is 15.7mm, and the width P is 10mm; The thickness of the upper PCB board (4-1-1) and the lower PCB board (4-1-2) are both h b2 =1mm, the thickness of the middle PCB board (4-1-3) is h b1 =2mm.

5. The system for adjusting a frequency selective absorber according to any one of claim 4, wherein: The center of the middle PCB (4-1-3) is opened with a diameter D v The metalized via is 2.6mm.

6. The system for adjusting a frequency selective absorber according to claim 2 or 3, characterized in that: The container (4-3) is a truncated cone, and the container base (4-3-1) is a rectangular parallelepiped with at least two square faces, and the side length of the square is 10 mm; The maximum thickness of the container base (4-3-1) is h1 = 4.3 mm, and the thickness of the inner space of the container base (4-3-1) is h4 = 2.3 mm; The inner space of the container (4-3) is equipped with a vertical water pipe with a height of h2=9.8mm and a diameter of r a3 =2mm, the height of the internal space of the container (4-3) is h3=8mm, and the maximum distance between the outer surface of the water pipe and the inner wall of the container (4-3) is l b3 =4mm; The outer diameter r of the upper surface of the container (4-3) a1 =4mm, inner diameter r of the upper surface of the container (4-3) a2 =3mm, inner diameter r of the lower surface of the container (4-3) a4 =8mm, outer diameter r of the lower surface of the container (4-3) a5 =9.5mm.

7. The system for adjusting a frequency selective absorber according to claim 1, wherein: A 50% volume concentration propylene glycol aqueous solution is contained in the liquid storage tank (5).

8. The system for adjusting a frequency selective absorber according to claim 1, wherein: The dielectric substrate and reflective frequency selective surface (4-2) of each PCB board are made of F4BM220 dielectric material with a relative dielectric constant of 2.20 and a loss tangent of 0.001.

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