High-order dual-band band-pass frequency selective surface

Abstract

The invention relates to the technical field of electromagnetic fields and microwaves, in particular to a high-order dual-band band-pass frequency selective surface, which comprises an upper metal layer, a dielectric substrate and a lower metal layer, and is characterized in that the dielectric substrate is arranged between the upper metal layer and the lower metal layer; a large rectangular ring gap and four small rectangular ring gaps are etched on the upper metal layer and the lower metal layer respectively, the four small rectangular ring gaps are located on the four edges of the large rectangular ring gap, and four small rectangular metal patches, a large rectangular metal patch and irregular peripheral metal patches are adopted after etching. According to the invention, the overall performance of the frequency selective surface can be enhanced, so that the frequency selective surface shows more excellent selectivity and stability in multi-band application.

Description

Technical Field

[0001] The present application relates to the field of electromagnetic field and microwave technology, and in particular to a high-order dual-band bandpass frequency selective surface. Background Art

[0002] A frequency selective surface is a spatial filter composed of a periodic arrangement of passive resonant units, which exhibits total reflection or total transmission characteristics near the unit resonant frequency. As the requirements for multi-band communications in radar and communication equipment continue to increase, the realization of multi-band frequency selective surfaces with high selectivity, high isolation, and in-band flatness has become the key to meeting the needs. Due to its structural limitations, traditional single-layer frequency selective surfaces can only provide a limited number of resonant units, so it is difficult to achieve multiple independent passbands and high-order filtering characteristics in the design. In addition, although the introduction of active devices such as varactor diodes and PIN diodes can achieve dynamic tuning and dual-frequency response, due to the power consumption problems of these active components themselves, long-term use will lead to a decrease in the efficiency of the overall system. Summary of the invention

[0003] (1) Technical issues to be solved

[0004] The present application provides a high-order dual-band bandpass frequency selective surface, which solves the technical problem that the frequency of a single-layer frequency selective surface is limited and the dual-band frequency selective surface loaded with active devices has high power consumption.

[0005] (2) Technical solution

[0006] The present application provides a high-order dual-band bandpass frequency selective surface, comprising an upper metal layer, a dielectric substrate and a lower metal layer, wherein the dielectric substrate is arranged between the upper metal layer and the lower metal layer;

[0007] The upper metal layer and the lower metal layer both have a large rectangular ring gap and four small rectangular ring gaps etched on the metal layer, and the four small rectangular ring gaps are located on the four sides of the large rectangular ring gap. After etching, four small rectangular metal patches, one large rectangular metal patch and irregular peripheral metal patches are used.

[0008] Furthermore, it also includes an intermediate metal layer; the dielectric substrate includes an upper dielectric substrate and a lower dielectric substrate;

[0009] The upper dielectric substrate is arranged between the upper metal layer and the middle metal layer, and the lower dielectric substrate is arranged between the middle metal layer and the lower metal layer; the middle metal layer adopts a cross-shaped metal patch.

[0010] Furthermore, the upper dielectric substrate and the lower dielectric substrate are both made of F4BM300, and the relative dielectric constant is 3.

[0011] Furthermore, the thickness of the upper dielectric substrate and the lower dielectric substrate are both 0.762 mm.

[0012] Furthermore, the thickness of the upper metal layer, the middle metal layer and the lower metal layer are all 0.018 mm.

[0013] Furthermore, a unit period of the high-order dual-band passband frequency selective surface is 16 mm.

[0014] Furthermore, the side lengths of the large rectangular metal patch and the small rectangular ring gap are both 4.42 mm, the side length of the small rectangular patch is 1.8 mm, the distance between the large rectangular metal patch and the small rectangular metal patch is 2.47 mm, the width of the small rectangular ring gap is 3.54 mm, and the distance between the small rectangular metal patch and the outer metal patch is 1.8 mm.

[0015] Furthermore, the side length of the small rectangular patch of the cross-shaped metal patch is 1 mm, and the side length of the cross-shaped metal patch is 9 mm.

[0016] Furthermore, the cross-shaped metal patch acts as a parallel inductor to couple with the upper metal layer and the lower metal layer.

[0017] Furthermore, the upper metal layer, the lower metal layer and the middle metal layer are all symmetrical about their respective centers, and the upper metal layer, the lower metal layer and the middle metal layer as a whole are rotationally symmetrical about the cross-shaped metal patch in the vertical incident direction.

[0018] (3) Beneficial effects

[0019] The above technical solution of the present application has the following advantages:

[0020] The high-order dual-band bandpass frequency selective surface provided by the present application can not only increase the number of resonant units by superimposing multiple metal layers and dielectric layers, but also utilize the mutual coupling between the layers to enhance the overall performance of the frequency selective surface. This design has multiple independent resonant frequencies, thereby forming multiple passbands, and transmission zeros can be generated between each passband to achieve good isolation. The multi-layer structure can also promote more complex electromagnetic wave interactions, thereby producing high-order filtering characteristics, so that the frequency selective surface exhibits better selectivity and stability in multi-band applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A three-dimensional graph of the bandpass frequency selective surface for the high-order dual-band provided for this application;

[0023] Figure 2 A side view of a high-order dual-band bandpass frequency selective surface provided for the present application;

[0024] Figure 3 The upper metal layer and the lower metal layer annular aperture array diagram provided for this application;

[0025] Figure 4 The middle layer cross patch diagram provided for this application;

[0026] Figure 5 An S parameter curve diagram of the upper metal layer and the upper dielectric substrate combination provided by the present application when the incident wave is vertically incident with TE polarization or TM polarization;

[0027] Figure 6 An S parameter curve diagram of a vertically incident wave when the incident wave is TE polarized or TM polarized for the combination of the upper and lower metal layers and the upper and lower dielectric substrates provided by the present application;

[0028] Figure 7 The S parameter curve diagram of the incident wave at vertical incidence when TE polarization is applied after the cross-shaped patch in the middle layer is introduced provided by the present application;

[0029] Figure 8 The S parameter curve diagram of the incident wave at vertical incidence when the TM polarization is introduced after the middle layer cross-shaped patch is provided in the present application;

[0030] Fig. 9 This is a transmission coefficient curve diagram at different incident angles for TE polarization provided in this application. DETAILED DESCRIPTION

[0031] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0032] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0033] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. appearing in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways.

[0035] In view of the technical problem that the frequency of a single-layer frequency selective surface is limited and the power consumption of a dual-band frequency selective surface loaded with active devices is high, this application proposes to use multi-layer cascade technology to design a high-order dual-bandpass frequency selective surface. Compared with a single-layer frequency selective surface with single-order filtering, a multi-layer frequency selective surface can generate multi-order filtering characteristics, thereby achieving a multi-band or wide-band frequency selective response; the traditional frequency selective surface only considers the first passband, while this application considers the second passband characteristics of the frequency selective surface, making it more widely used.

[0036] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0037] like Figure 1As shown, an embodiment of the present application provides a high-order dual-band bandpass frequency selective surface, including an upper metal layer, a dielectric substrate and a lower metal layer, wherein the dielectric substrate is arranged between the upper metal layer and the lower metal layer; a large rectangular ring gap and four small rectangular ring gaps are etched on the metal layer of the upper metal layer and the lower metal layer, and the four small rectangular ring gaps are located on the four sides of the large rectangular ring gap, and after etching, four small rectangular metal patches, one large rectangular metal patch and irregular peripheral metal patches are used.

[0038] The arrangement of metal patches and gaps in the upper metal layer or the lower metal layer can be equivalent to an inductor and a capacitor in parallel, both of which can produce a frequency selective passband. The frequency of the passband can be controlled by changing the size of the metal patch or the size of the gap.

[0039] This structure adopts a double-layer frequency selective surface cascade structure of upper and lower metal layers, which are coupled through a dielectric plate, which can increase the impedance of a single-layer frequency selective surface, thereby improving the transmission coefficient; coupling will also occur between adjacent rectangular metal patches in the upper and lower metal layers in the vertical direction, thereby causing a transformation in transmission impedance at the high frequency of the passband, thereby producing a high-order bandpass characteristic.

[0040] Through the designed upper and lower metal patches and their gap layout, transmission zeros are generated at multiple frequency points, which enhances the isolation between passbands, effectively reduces the interference between bands, and realizes dual-frequency bandpass response.

[0041] like Figure 1 and Figure 2 As shown, in some embodiments, an intermediate metal layer is also included; the dielectric substrate includes an upper dielectric substrate and a lower dielectric substrate; the upper dielectric substrate is arranged between the upper metal layer and the intermediate metal layer, and the lower dielectric substrate is arranged between the intermediate metal layer and the lower metal layer; the intermediate metal layer adopts a cross-shaped metal patch.

[0042] In some embodiments, the upper dielectric substrate and the lower dielectric substrate are both made of F4BM300, and the relative dielectric constant is 3.

[0043] like Figure 2 As shown, in some embodiments, the thickness h1 of the upper dielectric substrate and the lower dielectric substrate is 0.762 mm.

[0044] like Figure 2 As shown, in some embodiments, the thickness h2 of the upper metal layer, the middle metal layer and the lower metal layer are all 0.018 mm.

[0045] like Figure 1As shown, in some embodiments, the unit period p of the high-order dual-band passband frequency selective surface is 16 mm.

[0046] like Figure 3 As shown, in some embodiments, the side length a of the large rectangular metal patch and the small rectangular ring gap is 4.42 mm, the side length b of the small rectangular patch is 1.8 mm, the distance c between the large rectangular metal patch and the small rectangular metal patch is 2.47 mm, the width e of the small rectangular ring gap is 3.54 mm, and the distance d between the small rectangular metal patch and the outer metal patch is 1.8 mm.

[0047] like Figure 4 As shown, in some embodiments, the side length w of the small rectangular patch of the cross-shaped metal patch is 1 mm, and the side length l of the cross-shaped metal patch is 9 mm.

[0048] In some embodiments, the cross-shaped metal patch acts as a parallel inductor to couple with the upper metal layer and the lower metal layer.

[0049] In some embodiments, the upper metal layer, the lower metal layer and the middle metal layer are all symmetrical about their respective centers, and the upper metal layer, the lower metal layer and the middle metal layer as a whole are rotationally symmetrical about the cross-shaped metal patch in the vertical incident direction.

[0050] The high-order dual-bandpass frequency selective surface is composed of two dielectric substrates and three metal layers. The three metal layers are an upper metal layer, a middle metal layer and a lower metal layer, which are separated by two dielectric substrates. The structure is as follows Figure 1 As shown. Both dielectric plates are made of F4BM300, with a relative dielectric constant of 3. The thicknesses of the dielectric plate and the metal layer are h1 = 0.762 mm and h2 = 0.018 mm, respectively. Figure 2 The unit period is p = 16 mm.

[0051] The upper metal layer is exactly the same as the lower metal layer, and is formed by etching a large rectangular ring gap and four small rectangular ring gaps on the metal layer. The four small rectangular ring gaps are located on the four sides of the large rectangular ring gap. After etching, it is composed of four small rectangular metal patches, one large rectangular metal patch and irregular peripheral metal patches, such as Figure 3 As shown: a=4.42mm, b=1.8mm, c=2.47mm, e=3.54mm, d=1.06mm, where a is the side length of the large rectangular metal patch and the small rectangular ring gap, b is the side length of the small rectangular metal patch, c is the distance between the large rectangular metal patch and the small rectangular metal patch, e is the width of the small rectangular ring gap, and d is the distance between the small rectangular metal patch and the outer metal patch.

[0052] The middle metal layer is a cross-shaped metal patch. Figure 4 As shown in the figure, the specific size parameters are: w = 1mm, l = 9mm, w is the side length of the small rectangular patch, and l is the side length of the cross-shaped metal patch. The electromagnetic wave is incident along the z direction, the TE polarization direction is the y direction, and the TM polarization direction is the x direction.

[0053] This structure introduces a cross-shaped metal patch between the upper and lower metal layers, separated by two layers of dielectric plates. The cross-shaped patch acts as a parallel inductor, coupling with the upper and lower metal layers, so that the impedance of this structure is enhanced at high frequencies, thereby improving the performance of high-order bandpass characteristics.

[0054] The upper and lower metal layers are a planar structure symmetrical about the center, the cross-shaped metal patch layer is also a planar structure symmetrical about the center, and the three metal layers are rotationally symmetrical about the cross-shaped metal patch in the vertical incident direction, so this structure is insensitive to the angle of the incident wave.

[0055] Figure 5 The S parameters of the upper metal layer and the upper dielectric substrate layer combined when TE polarization or TM polarization is vertically incident, forming a passband at the resonant frequency of 9.94 GHz. Figure 6 When the upper and lower metal layers are separated by the upper and lower dielectric substrate layers, TE polarization or TM polarization is vertically incident, the resonant frequency 9.94GHz moves to a low frequency of 8.61GHz, and the first passband is formed at this frequency. Due to the interaction between the upper and lower metal layers, two transmission zeros are generated at frequencies of 12.32GHz and 14.58GHz, with a trend of the second passband. The existence of these two zeros effectively increases the isolation between the passbands and reduces inter-band interference, thereby improving the performance of the frequency selective surface in multi-band applications.

[0056] In order to Figure 6 The second passband has high-order characteristics. A cross-shaped patch is introduced between the upper and lower metal layers. Its vertical incidence frequency response under TE polarization is as follows: Figure 7 As shown. With this design, a transmission zero is added at 10.77 GHz between the two passbands, which enhances the isolation effect between the passbands. At this time, the resonant frequency of the first passband is further moved to 6.55 GHz. In the second passband, due to the multiple coupling effects between the cross-shaped patch and the upper and lower metal layers, three independent resonant frequencies are generated at 12.31 GHz, 13.16 GHz, and 14.02 GHz, respectively. For the TM polarization, it is similar to the TE polarization.

[0057] Figure 7This is the frequency response of vertical incidence at TE polarization, where the first passband fractional bandwidth is 24.8%, from 5.79 GHz to 7.43 GHz; the second passband fractional bandwidth is 14.8%, from 12.41 GHZ to 14.40 GHz. Figure 8 The frequency response of the vertical incidence under TM polarization is shown in Figure 1. The first passband fractional bandwidth is 23.3%, from 5.79 GHz to 7.32 GHz, and the second passband fractional bandwidth is 14.7%, from 12.29 GHZ to 14.25 GHz. The results of TM polarization and TE polarization are almost the same, indicating that the proposed filter is polarization insensitive.

[0058] Fig. 9 is the transmission coefficient of the frequency selective surface at different incident angles of TE polarization. The frequency selective surface proposed in this application can work effectively at 45°. When the incident angle increases, the impedance of the frequency selective surface increases, resulting in a decrease in the -3dB bandwidth of TE polarization. Specifically, when the incident angles θ are 0°, 15°, 30° and 45°, respectively, the -3dB bandwidth of the first passband is 24.8%, 22.5%, 19.8% and 16.1%, respectively, while the -3dB bandwidth of the second passband is 14.8%, 12.12%, 10.6% and 8.0%, respectively. The results show that the passband frequency response of TE polarization has good stability at different incident angles.

[0059] The high-order dual-band bandpass frequency selective surface provided by the present application realizes a dual-bandpass response. Through the designed upper and lower metal patches and their gap layout, transmission zeros are generated at multiple frequency points, which enhances the isolation between the passbands and effectively reduces the interference between the bands. Due to the multiple coupling mechanisms formed between the cross-shaped patches in the middle layer and the upper and lower metal layers, multiple independent resonance points are formed within a specific frequency range, thereby showing obvious high-order bandpass characteristics.

[0060] Common frequency selective surfaces are difficult to achieve high-order response, but the structural unit designed in this scheme achieves a third-order filter response in the second passband and has rectangular selectivity. Compared with a single-layer frequency selective surface, the multi-layer frequency selective surface designed in this application achieves two filter passbands and has better isolation.

[0061] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application.

[0062] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present application is not limited to the specific structures described above and shown in the figures. In addition, for the sake of simplicity, detailed descriptions of known methods and technologies are omitted here.

[0063] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A high-order dual-band bandpass frequency selective surface, characterized in that: It comprises an upper metal layer, a dielectric substrate and a lower metal layer, wherein the dielectric substrate is arranged between the upper metal layer and the lower metal layer; The upper metal layer and the lower metal layer both have a large rectangular ring gap and four small rectangular ring gaps etched on the metal layer, and the four small rectangular ring gaps are located on the four sides of the large rectangular ring gap. After etching, four small rectangular metal patches, one large rectangular metal patch and irregular peripheral metal patches are used.

2. The high-order dual-band bandpass frequency selective surface as claimed in claim 1, characterized in that: It also includes an intermediate metal layer; the dielectric substrate includes an upper dielectric substrate and a lower dielectric substrate; The upper dielectric substrate is arranged between the upper metal layer and the middle metal layer, and the lower dielectric substrate is arranged between the middle metal layer and the lower metal layer; the middle metal layer adopts a cross-shaped metal patch.

3. The high-order dual-band bandpass frequency selective surface as claimed in claim 2, characterized in that: The upper dielectric substrate and the lower dielectric substrate are both made of F4BM300, and the relative dielectric constant is 3.

4. The high-order dual-band bandpass frequency selective surface as claimed in claim 2, characterized in that: The thickness of the upper dielectric substrate and the lower dielectric substrate are both 0.762 mm.

5. The high-order dual-band bandpass frequency selective surface as claimed in claim 2, characterized in that: The thickness of the upper metal layer, the middle metal layer and the lower metal layer are all 0.018 mm.

6. The high-order dual-band bandpass frequency selective surface as claimed in claim 1, characterized in that: The unit period of the high-order dual-band passband frequency selective surface is 16 mm.

7. The high-order dual-band bandpass frequency selective surface as claimed in claim 1, characterized in that: The side lengths of the large rectangular metal patch and the small rectangular ring gap are both 4.42 mm, the side length of the small rectangular patch is 1.8 mm, the distance between the large rectangular metal patch and the small rectangular metal patch is 2.47 mm, the width of the small rectangular ring gap is 3.54 mm, and the distance between the small rectangular metal patch and the outer metal patch is 1.8 mm.

8. The high-order dual-band bandpass frequency selective surface as claimed in claim 2, characterized in that: The side length of the small rectangular patch of the cross-shaped metal patch is 1 mm, and the side length of the cross-shaped metal patch is 9 mm.

9. The high-order dual-band bandpass frequency selective surface as claimed in claim 2, characterized in that: The cross-shaped metal patch acts as a parallel inductor and couples with the upper metal layer and the lower metal layer.

10. The high-order dual-band bandpass frequency selective surface as claimed in claim 2, characterized in that: The upper metal layer, the lower metal layer and the middle metal layer are all symmetrical about their respective centers, and the upper metal layer, the lower metal layer and the middle metal layer are rotationally symmetrical about the cross-shaped metal patch in a vertical incident direction.

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