Miniaturized dual-passband frequency selective surface structure and signal receiving equipment

Abstract

The invention provides a miniaturized dual-passband frequency selective surface structure and signal receiving equipment, and belongs to the technical field of electromagnetic waves. The problems that the size of an existing FSS structure unit is generally large, the structure thickness is large, and the urgent requirement for miniaturization of a device at present is difficult to meet are solved. The structure is composed of a plurality of periodically arranged FSS unit structures, each FSS unit structure comprises a first metal layer, a dielectric substrate and a second metal layer which are sequentially arranged from top to bottom, the first metal layer is provided with an aperture unit, and the second metal layer is a complementary structure of the first metal layer. The patch unit is composed of a patch unit with the same shape and size as the aperture unit on the first metal layer, the shape of the aperture unit is swastika-shaped deformation, and specifically, at least two parallel strips perpendicular to the edges are arranged on the four edges of the swastika shape; the structure provided by the invention has a good miniaturization effect, meets the requirement of miniaturization of equipment, and can realize excellent frequency selectivity in a complex environment at the same time.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electromagnetic waves, in particular to a miniaturized double-passband frequency selective surface structure and a signal receiving device. BACKGROUND

[0002] A frequency selective surface (FSS) is a periodic array structure composed of metal patch units or aperture units on a metal screen, and the FSS is essentially a spatial filter capable of selectively transmitting or reflecting electromagnetic waves in a specific frequency range, and has been widely used in radar stealth, electromagnetic shielding, wireless communication systems and other fields. The filtering characteristics of the frequency selective surface structure depend not only on its geometric shape, size, arrangement and dielectric loading method, but also on the incidence angle and polarization of the incident electromagnetic wave.

[0003] With the rapid development of modern communication and radar technology, the demand for multi-band communication technology is increasing, and the current frequency selective surface (FSS) applied to satellite communication frequency bands has the problems of single filtering frequency band, large oblique incidence response deviation, poor structural stability, and is difficult to meet the diversified scene and higher performance application requirements. At the same time, the size of the FSS structure unit is generally large, and the structure thickness is high, which is difficult to meet the urgent demand for device miniaturization. SUMMARY

[0004] In order to solve the above technical problems, the application provides a miniaturized double-passband frequency selective surface structure and a signal receiving device.

[0005] The technical scheme adopted by the application is as follows: a miniaturized double-passband frequency selective surface structure is composed of M*N periodic FSS unit structures, the FSS unit structure comprises a first metal layer, a dielectric substrate and a second metal layer arranged in sequence from top to bottom, the first metal layer is provided with an aperture unit, and the second metal layer is a complementary structure of the first metal layer and is composed of patch units with the same shape and size as the aperture unit on the first metal layer. The shapes of the aperture unit and the patch unit are deformations of the "swastika" shape, and specifically, at least two parallel strips perpendicular to the edges are arranged on the four edges of the "swastika" shape.

[0006] Further, the center of the "swastika" shape can also be set to a "kou" shape.

[0007] Further, the FSS unit structure works in the C band and the X band.

[0008] Further, the first metal layer and the second metal layer are made of Au, Ag, Cu or Al metal, and are prepared on the dielectric substrate by using a photolithography process or a printed circuit board process.

[0009] Further, the material of the dielectric substrate is selected from fiber, resin material or composite material of fiber and resin.

[0010] Further, the dielectric substrate is made of F4B-2 polytetrafluoroethylene, the dielectric constant is 2.65, and the thickness is 0.5-2 mm.

[0011] Further, M and N are integers greater than 30.

[0012] Further, the arrangement of the FSS unit structure is in a square shape.

[0013] Further, the size of the FSS unit structure is 0.088 λ ×0.088 λ , λ is the wavelength corresponding to the first resonant frequency in the vacuum medium.

[0014] A signal receiving device comprises an antenna body, and the small-sized double-passband frequency selective surface structure is disposed on the antenna body.

[0015] The frequency selective surface structure provided by the application has good double-passband frequency selection characteristics, the first frequency band has a resonant center frequency of 4.4 GHz, a -3dB bandwidth of 0.92 GHz, and an insertion loss of -0.17 dB, the second frequency band has a resonant center frequency of 10.1 GHz, a -3dB bandwidth of 0.96 GHz, and an insertion loss of -0.5 dB. The structure has extremely strong selective wave transmission characteristics near the two frequency points of 4.4 GHz and 10.1 GHz, has low in-band loss, has small changes in resonant frequency and bandwidth when TE and TM polarized incident waves are irradiated at different angles, has stable filtering characteristics, is not sensitive to electromagnetic waves of different incident angles and polarizations, can ensure that satellite communication signals in the C band and the X band are not disturbed by other frequency signals, and can ensure communication stability. BRIEF DESCRIPTION OF DRAWINGS

[0016] The application will be further described below with reference to the drawings: Figure 1 is a perspective view of a small-sized double-passband frequency selective surface unit structure provided by an embodiment of the application; Figure 2 is a side view of Figure 1 ; Figure 3 is a schematic view of a metal layer structure in Figure 1 , in which (a) is a first metal layer aperture unit, and (b) is a second metal layer patch unit; Figure 4 is a perspective view of a double-passband frequency selective surface multi-unit structure provided by an embodiment of the application; Figure 5 A transmission characteristic curve of a dual-passband frequency selective surface in TE polarization with perpendicular electromagnetic wave incidence provided in an embodiment of this application; Figure 6 A transmission characteristic curve of a dual-passband frequency selective surface in TM polarization with electromagnetic waves incident perpendicularly, provided in an embodiment of this application. Figure 7 The transmission characteristic curves of electromagnetic waves incident at different incident angles in TE polarization on the dual-passband frequency selective surface provided in the embodiments of this application; Figure 8 The transmission characteristic curves of electromagnetic waves incident at different incident angles in TM polarization on the dual-passband frequency selective surface provided in the embodiments of this application; In the figure: 1 is the first metal layer, 2 is the dielectric substrate, and 3 is the second metal layer. Detailed Implementation

[0017] like Figures 1 to 8 As shown, this application provides a miniaturized dual-passband frequency selective surface structure, which is composed of M*N periodically arranged FSS unit structures. During processing, M and N are chosen to be integers greater than 30. Each FSS unit structure consists of a first metal layer 1, a dielectric substrate 2, and a second metal layer 3 from top to bottom. The first metal layer 1 is composed of periodically arranged sub-aperture units on the metal screen. Specifically, four sub-aperture units of the same shape are arranged and rotated 90° counterclockwise around the center, respectively located in four regions. The four sub-aperture units are connected sequentially by an arm to form a central connection unit. The second metal layer 2 is composed of periodically arranged patch units on the metal screen. The second metal layer 2 is a complementary structure to the first metal layer 1 and is composed of patch units with the same shape and size as the first metal layer 1.

[0018] The first metal layer 1 and the second metal layer 2 can be Au, Ag, Cu, or Al, and are fabricated on the dielectric substrate 2 using photolithography or printed circuit board processes. The dielectric substrate 2 can be made of fiber, resin, or a composite material of fiber and resin. The thickness of the dielectric substrate 2 is determined based on the resonant frequency, operating bandwidth, and in-band loss requirements.

[0019] In this application, the FSS unit structure of the first metal layer 1 is an aperture unit composed of four sub-aperture units, which is evolved and designed based on the "卍" - shaped aperture unit. Specifically, it is a central connection unit obtained by introducing parallel strips perpendicular to the four sides of the "卍" - shaped structure. The addition of the strips is equivalent to increasing the equivalent inductance, and at the same time, it can reduce the distance between units, which is equivalent to increasing the equivalent capacitance, achieving the purpose of reducing the resonance frequency, that is, realizing the miniaturization of the unit structure, thereby improving the angular stability of the frequency response. And the center of the "卍" - shaped structure can be connected by a cross - shaped or square - shaped structure.

[0020] In this application, the FSS unit structure of the second metal layer 1 is a patch unit composed of four sub - patch units, which is a central connection unit obtained by introducing parallel strips perpendicular to the four sides of the "卍" - shaped structure, and has the same shape and size as the aperture unit of the first metal layer 1.

[0021] As Figures 1-4 shown in the structure, a specific unit structure form composed of four E - shaped sub - units connected by a square - shaped center is given. The E - shaped sub - aperture units connected by the square - shaped structure and the E - shaped sub - patch units connected by the square - shaped structure are respectively loaded on both sides of the dielectric substrate 2. Figures 5-8 The verification results in

[0022] are also obtained by simulating based on the structure of the E - shaped unit. However, in the embodiments of this application, it is not limited to only the E - shaped unit. According to specific requirements, 1, 2, 3 or more parallel strips can be further introduced on the four sides based on the E - shaped structure. This application only verifies the performance of the frequency - selective surface structure proposed in this application based on the most basic E - shaped unit.

[0023] The dual - band filtering characteristic FSS structure designed in this application cascades a patch unit structure with the same shape and size as the aperture unit of the first metal layer 1 on the second metal layer 2, ensuring the introduction of a transmission zero point near the resonance frequency of the filtering passband generated on the first metal layer 1, thereby realizing a stable dual - band filtering characteristic. According to the resonance frequency, working bandwidth, and in - band loss requirements of the frequency - selective surface, the material and thickness of the dielectric substrate 2 are determined. In this embodiment, the dielectric substrate 2 uses F4B - 2 polytetrafluoroethylene with a dielectric constant of 2.65, and the thickness can be 0.5 - 2 mm.

[0024] This application also proposes a signal receiving device, including an antenna body on which a frequency selective surface structure is deployed.

[0025] The dual-passband frequency selective surface proposed in this application embodiment will be further described below with reference to the accompanying drawings and specific embodiments. The FSS unit structure of this embodiment includes, from top to bottom, a first metal layer 1, a dielectric substrate, and a second metal layer 2, as shown below. Figure 1 As shown. In this embodiment, the FSS cell structure adopts a square arrangement, and the array period is... D x = D y =6mm. The first metal layer 1 is made of copper and has four E-shaped sub-aperture unit structures, which are arranged in a 90° counterclockwise rotation around the central structure and located in four regions respectively. The four E-shaped sub-aperture units are connected in sequence by an arm to form a central connection structure, as shown in the figure. Figure 3 As shown in (a); the dielectric substrate 2 is F4B-2 polytetrafluoroethylene, with a relative permittivity of [missing value]. ε r =2.65, thickness h =0.5mm. The second metal layer 2 is a patch unit structure made of copper, with the same shape and size as the aperture unit of the first metal layer 1, forming a complementary structure with the aperture unit of the first metal layer 1. The patch unit structure is as follows: Figure 3 As shown in (b). The detailed geometric parameters of the first metal layer 1 and the second metal layer 2 are shown in Table 1. By adjusting the relevant structural parameters, the resonant frequency, operating bandwidth, in-band loss, and other frequency response characteristics of the FSS unit structure can be adjusted.

[0026] Table 1 FSS Unit Structure Parameters

[0027] Figure 5 The transmission characteristic curves of the FSS cell structure in this embodiment under vertical incidence of TE-polarized waves show that the proposed FSS structure exhibits dual-band filtering characteristics. The two resonant frequencies are 4.4 GHz and 10.1 GHz. At 4.4 GHz, the -3 dB bandwidth is 0.92 GHz with an insertion loss of -0.17 dB. At 10.1 GHz, the -3 dB bandwidth is 0.96 GHz with an insertion loss of -0.5 dB. This means that in TE polarization mode, the FSS cell structure achieves good bandpass filtering characteristics near 4.4 GHz and 10.1 GHz. The size of this FSS cell structure is only 0.088 mm. λ ×0.088 λ ( λ(where the first resonant frequency corresponds to the wavelength in a vacuum medium), this structure offers significant advantages in miniaturization.

[0028] Figure 6 The transmission characteristic curve of the FSS unit structure under vertical incidence of TM polarized waves, as shown in the example, shows that the FSS unit structure has dual-band selectivity. The two resonant frequencies are 4.41 GHz and 10 GHz, respectively. At the 4.41 GHz frequency point, the -3 dB bandwidth is 0.88 GHz and the insertion loss is -0.2 dB. At the 10 GHz frequency point, the -3 dB bandwidth is 0.94 GHz and the insertion loss is -0.65 dB. That is, the FSS unit structure still has excellent filtering characteristics near 4.41 GHz and 10 GHz under the incidence of TM polarized waves.

[0029] comprehensive Figure 5 and Figure 6 The filtering characteristics show that this structure has stable dual-passband filtering characteristics in both TE and TM modes, with the center resonant frequencies of the two frequency bands remaining stable, demonstrating excellent polarization stability.

[0030] Furthermore, in practical engineering applications of FSS, the incident angle and polarization of the incident wave are often uncertain. Therefore, it is necessary to consider the frequency response characteristics of electromagnetic waves under oblique incidence conditions with different polarization modes. To study the angular stability of the FSS unit structure in this embodiment, Figure 7 and Figure 8 The transmission characteristic curves of TE polarized waves and TM polarized waves incident on the FSS unit structure at 0°, 30°, 45° and 60° are shown respectively.

[0031] Depend on Figure 7 It can be seen that as the incident angle of the TE polarized wave increases, the maximum center resonant frequency shift of the two passbands is less than 0.5%, the insertion loss is less than -0.7dB, and the frequency deviation is within an acceptable range, exhibiting good signal transmission capability and anti-interference capability. The FSS unit structure has good angular stability at 4.4GHz and 10.1GHz. Table 2 shows the filtering characteristic parameters of the FSS unit structure in this embodiment under different incident angles of the TE polarized wave.

[0032] Table 2 Filtering characteristic parameters of FSS unit structure under different angles of TE polarized wave incidence.

[0033] from Figure 8As can be seen, under TM polarized wave incidence at angles of 0° to 60°, the FSS unit structure still exhibits good frequency selectivity near 4.4 GHz and 10.1 GHz, with center resonant frequency shifts of only 0.03 GHz and 0.12 GHz for the two passbands, a maximum center resonant frequency shift of less than 1.2%, and an insertion loss of less than -0.7 dB, demonstrating excellent angular stability. Table 3 shows the filtering characteristic parameters of the FSS unit structure in this embodiment under TM polarized wave incidence at different angles.

[0034] Table 3 Filtering characteristics of FSS unit structure under different incident angles of TM polarized waves.

[0035] comprehensive Figure 7 and Figure 8 As can be seen from the transmission characteristic curve and the filtering characteristic parameters in Tables 2 and 3, this FSS unit structure has stable dual-passband filtering characteristics in both the C-band and X-band when TE-polarized and TM-polarized waves are irradiated with incident waves at incident angles of 0°, 30°, 45° and 60°, respectively. This structure has good angular stability and polarization stability.

[0036] The miniaturized dual-passband frequency selective surface structure proposed in this embodiment exhibits strong filtering characteristics near the 4.4GHz and 10.1GHz frequencies through a dual-screen cascade approach. The size of the FSS unit structure is only 0.088λ×0.088λ (λ is the wavelength of the first resonant frequency in the vacuum medium), demonstrating excellent miniaturization. The small structural size meets the requirements for device miniaturization. The frequency response deviation is small when TE and TM polarized incident waves are incident at different angles, achieving good angular stability and polarization stability, while ensuring low insertion loss. It also achieves excellent frequency selectivity in complex environments.

[0037] The miniaturized dual-passband frequency selective surface structure proposed in this embodiment has extremely strong filtering characteristics when applied to the C-band and X-band, effectively preventing satellite communication signals from being interfered with by other frequency signals.

[0038] The miniaturized dual-passband filter (FSS) structure proposed in this application utilizes four centrally symmetrical E-shaped aperture unit structures in the first metal layer 1, connected sequentially by a horizontal arm to form a central connection structure. This further increases the equivalent inductance and equivalent capacitance of the central connection unit, effectively reducing the resonant frequency and achieving miniaturization of the unit structure. Simultaneously, the centrally symmetrical structure design ensures good polarization stability. The effective electrical length can be further increased by adjusting the E-shaped unit structure, such as increasing the number of E-shaped unit arms, thereby lowering the resonant frequency and improving the miniaturization characteristics.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A miniaturized dual-band frequency selective surface structure, comprising M*N periodically arranged FSS unit structures, each FSS unit structure comprising, from top to bottom, a first metal layer, a dielectric substrate, and a second metal layer, the first metal layer having an aperture unit disposed thereon, the second metal layer being a complementary structure of the first metal layer, and being composed of a patch unit identical in shape and size to the aperture unit on the first metal layer, characterized in that: The shape of the aperture unit and the patch unit is a deformation of the "swastika" shape, specifically, at least two parallel strips perpendicular to the four edges of the "swastika" shape are arranged on the four edges.

2. A miniaturized dual-passband FSS structure according to claim 1, characterized in that: The center of the "swastika" shape can also be arranged as a "mouth" shape.

3. A miniaturized dual-band frequency selective surface structure according to claim 1 or 2, characterized in that: The FSS unit structure works in C-band and X-band.

4. The miniaturized dual-band FSS structure according to claim 1 or 2, characterized in that: The first metal layer and the second metal layer are made of Au, Ag, Cu or Al metal, and are prepared on the dielectric substrate by using a photoetching process or a printed circuit board process.

5. A miniaturized dual-passband FSS structure according to claim 4, characterized in that: The material of the dielectric substrate is selected from fiber, resin material or a composite material of fiber and resin.

6. A miniaturized dual-passband FSS structure according to claim 5, characterized in that: The dielectric substrate is made of F4B-2 polytetrafluoroethylene, the dielectric constant is 2.65, and the thickness is 0.5-2 mm.

7. The miniaturized dual-passband FSS structure of claim 3, wherein: M and N are integers greater than 30.

8. The miniaturized dual-passband FSS structure according to claim 1 or 2, wherein: The arrangement mode of the FSS unit structure adopts a square shape.

9. A miniaturized dual-passband FSS structure according to claim 8, characterized in that: The size of the FSS unit structure is 0.088 λ x 0.088 λ , λ is the wavelength in a vacuum medium corresponding to the first resonance frequency.

10. A signal receiving device comprising an antenna body, characterized by: The antenna body is arranged with the miniaturized double-passband frequency selective surface structure as claimed in any one of claims 1-9.

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