A frequency selective surface unit with positive reflection gradient phase and selective surface

Abstract

The present invention discloses a frequency selective surface unit with a positive reflection gradient phase, comprising a dielectric substrate arranged on a top layer; a double-layer unit plate coupled and connected at a certain distance on a lower layer of the dielectric substrate; the double-layer unit plate comprising a first unit plate and a second unit plate; the first unit plate arranged on an upper layer of the second unit plate; a metal rectangular patch and an annular grid arranged on the surface of the single unit plate; the metal rectangular patch arranged inside the annular grid; and a cross-shaped metal patch arranged on the surface of the second unit plate. The present invention adopts a cascade structure of a simple FSS layer and a dielectric layer, so that the cladding structure can have a positive gradient reflection phase over a wider frequency range, thereby ensuring that the Fabry-Pérot resonant cavity antenna has broadband characteristics while improving gain.

Description

Technical Field

[0001] The invention belongs to the field of antennas and relates to a frequency selective surface unit with a positive reflection gradient phase and a selective surface. Background Art

[0002] Wideband high-gain antennas play an extremely important role in wireless communication fields such as satellite communications, remote control and navigation. Generally, the improvement of antenna gain can be achieved through two methods: antenna structure optimization or antenna array structure design. However, applying the above methods to improve antenna gain often leads to problems such as complex antenna structure, increased processing costs, enhanced mutual coupling between antennas, and difficulty in feeding network design. The Fabry-Pérot (FP for short) resonant cavity antenna is a high-gain, highly directional antenna that can avoid the shortcomings of traditional high-gain antennas such as complex structure, large size, and high cost, and can overcome the problems of large mutual coupling between array antennas and complex feeding. It is an effective solution for high-gain antenna design. However, the operating bandwidth of traditional FP resonant cavity antennas is relatively narrow, and there are great limitations in practical applications, making it difficult to meet the demand for high-gain antennas in broadband communications.

[0003] By rationally designing the cladding structure of the FP resonant cavity antenna, the gain bandwidth of the FP resonant cavity antenna can be effectively improved while increasing the antenna gain. Currently, high-gain FP resonant cavity antennas are mostly clad with a single layer. While this cladding can increase the antenna gain, it often narrows the antenna bandwidth (especially the gain bandwidth). Alternatively, while it can expand the antenna bandwidth, the effect is not significant, which still limits the antenna's application.

[0004] To improve the antenna gain, a metasurface covering can be placed above the antenna to form an FP resonant cavity structure, but this will affect the bandwidth of the antenna and cause the frequency band of the antenna to narrow. On the other hand, the current design structure of the metasurface is relatively complex and will produce a coupling effect with the antenna, which will affect its practical application. Summary of the Invention

[0005] In order to improve the antenna gain, a metasurface coating can be placed above the antenna to form an FP resonant cavity structure, but this will affect the bandwidth of the antenna, causing the frequency band of the antenna to become narrower. On the other hand, the current design structure of the metasurface is relatively complex and will produce a coupling effect with the antenna, which will affect its practical application. The present invention provides a technical solution adopted by the present invention: a frequency selective surface unit with a positive reflection gradient phase, comprising a dielectric substrate arranged on a top layer;

[0006] The lower layer of the dielectric substrate is coupled and connected with a double-layer unit board at a certain distance;

[0007] The double-layer unit plate includes a first unit plate and a second unit plate;

[0008] The first unit plate and the second unit plate are separated by a certain distance I;

[0009] The first unit board is arranged on an upper layer of the second unit board;

[0010] The upper surface of the second unit board is provided with a metal rectangular patch and an annular grid;

[0011] The metal rectangular patch is arranged inside the annular grid;

[0012] A cross-shaped metal patch is provided on the lower surface of the second unit board.

[0013] Furthermore, the rectangular metal patch, the cross-shaped metal patch, and the annular grid are all made of copper.

[0014] Furthermore: the metal rectangular patch is spaced a certain distance II from the frame of the first unit board.

[0015] The distance II>the distance I;

[0016] Furthermore: the dielectric substrate and the double-layer unit board are both square.

[0017] Furthermore: the annular grid and the metal rectangular patch are square.

[0018] Furthermore, the dielectric substrate is connected to the four corners of the double-layer unit board via nylon columns.

[0019] A frequency selective surface with a positive reflection gradient phase comprises a plurality of the frequency selective surface units.

[0020] The present invention provides a frequency selective surface unit and a selective surface with a positive reflection gradient phase. The selective surface is applied to a wide-band, high-gain Fabry-Pérot (FP) resonant cavity antenna. The present invention adopts a cascade structure of a simple FSS layer and a dielectric layer, so that the cladding structure can have a positive gradient reflection phase within a wider frequency range, thereby ensuring that the Fabry-Pérot resonant cavity antenna has wide-band characteristics while improving gain. A structural design method for integrating the coupling of a dielectric plate and an FSS unit is adopted to propose an FSS with a positive reflection gradient phase. The reflection phase of this structure varies positively with frequency in the range of 9GHz to 11GHz, ensuring that the antenna has a wider frequency band while improving gain. The experimental and simulation results are consistent to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are 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 labor.

[0022] Figure 1 It is the overall structure diagram of the FSS unit;

[0023] Figure 2 is the PRS reflection phase diagram;

[0024] Figure 3 It is the gain curve of FP antenna and feed antenna;

[0025] Figure 4 Figure 1 shows the FSS sample (a) dielectric substrate layer (b) upper surface of double-layer unit board (c) lower surface of double-layer unit board;

[0026] Figure 5 This is a sample picture of the FP antenna;

[0027] Figure 6 This is the FP antenna test diagram;

[0028] Figure 7 This is the measurement and simulation diagram of the prototype antenna S11;

[0029] Figure 8 This is the prototype antenna gain measurement and simulation diagram;

[0030] Figure 9 (a) is the 9.5GHz E-plane radiation pattern, (b) is the 9.5GHz H-plane radiation pattern, (c) is the 10GHz E-plane radiation pattern; (d) is the 10GHz H-plane radiation pattern, (e) is the 10.5GHz E-plane radiation pattern; (f) is the 10.5GHz H-plane radiation pattern. DETAILED DESCRIPTION

[0031] It should be noted that, unless there is any conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0034] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0035] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0036] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0037] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0038] Figure 1 The figure is a diagram of the overall structure of the FSS unit; a frequency selective surface unit with a positive reflection gradient phase, comprising a dielectric substrate arranged on a top layer;

[0039] The lower layer of the dielectric substrate is coupled with a double-layer unit board at a certain distance; the double-layer unit board adopts Rogers RT / duroid 5880 (εr=2.2, tanδ=0.0009)

[0040] The double-layer unit plate includes a first unit plate and a second unit plate;

[0041] The first unit plate and the second unit plate are separated by a certain distance I;

[0042] The first unit board is arranged on an upper layer of the second unit board;

[0043] The upper surface of the second unit board is provided with a metal rectangular patch and an annular grid;

[0044] The metal rectangular patch is arranged inside the annular grid; the first unit plate with the metal rectangular patch has a small reflection coefficient at low frequencies and gradually increases with increasing frequency, thus having the characteristics of a bandpass filter;

[0045] A cross-shaped metal patch is provided on the lower surface of the second unit board, and the border between the cross-shaped metal patch and the surface of the second unit board is 0;

[0046] The second unit board with a cross-shaped metal patch has a trend opposite to that of the first unit board. The reflection coefficient is large at low frequencies and gradually decreases with increasing frequency, showing the characteristics of a band-stop filter. Therefore, the FSS structure combining the two structures produces weak resonance in a wider frequency band, making the slope of the reflection phase frequency response curve in this band positive and having a higher reflection coefficient.

[0047] The dielectric substrate serves to increase the slope of the reflection gradient;

[0048] The metal rectangular patch, the cross-shaped metal patch, and the annular grid are all made of copper.

[0049] The metal rectangular patch is spaced a certain distance II from the frame of the single unit board.

[0050] The distance II>the distance I;

[0051] The dielectric substrate and the double-layer unit plate are both square.

[0052] The annular grid and the metal rectangular patch are square.

[0053] A frequency selective surface with a positive reflection gradient phase comprises a plurality of the frequency selective surface units.

[0054] Furthermore, the thickness of the dielectric substrate arranged on the top layer is t1 = 1 mm, and the thickness of the first unit board is t2 = 1 mm.

[0055] The spacing distance between the dielectric substrate and the first unit board is hc=2.5mm;

[0056] The width of the cross-shaped metal patch is w=1 mm;

[0057] The length of the metal rectangular patch is L=7.5 mm;

[0058] The length of the double-layer unit plate p=10 mm;

[0059] The length of the annular grid L1 = 9 mm;

[0060] In order to verify that the structure has a positive reflection gradient phase, full-wave simulation was performed using HFSS Microwave Studio software, with lattice unit cell boundary conditions all around to simulate an infinite periodic structure. Figure 2 is the PRS reflection phase diagram;

[0061] The structure has a positive reflection gradient phase in a wide frequency band.

[0062] Compared with the FSS in published literature, this structure is simpler in design, easier to implement, and has a wider frequency modulation range.

[0063] The FSS layer was simulated and observed using HFSS15.0. Figure 3 It is the gain curve of FP antenna and feed antenna; Figure 3 The reflection phase of the FSS is plotted in , including the ideal reflection phase of the FP resonant antenna. In addition, the reflection amplitude and phase of a single FSS are also plotted in Figure 2 It can be seen that if only one FSS (lower single frequency selective surface layer PRS1) is used, the frequency range of the normal reflection gradient phase is about 1 GHz. However, when two layers of FSS are used at the same time, the frequency range of the normal reflection phase gradient increases to 2 GHz, from Figure 2 It can also be observed that the designed FSS structure has a higher reflection slope.

[0064] Using the Fabry-Pérot resonant cavity principle, the designed FSS is placed as a cladding structure (PRS layer) above the air-loaded slot-coupled microstrip antenna. The two form a FP resonant cavity antenna, which can effectively improve the gain of the antenna and effectively increase the antenna gain bandwidth, such as Figure 3 shown. Figure 3 Simulated gain plots for the feed antenna and the FP resonant cavity antenna are plotted, demonstrating a significant improvement in the feed antenna's gain within the 8-11.8 GHz band. The FP resonant cavity antenna also achieves a relative gain bandwidth (3dB bandwidth) of approximately 33%, a significant improvement compared to conventional FP resonant cavity antennas.

[0065] In order to further verify the effectiveness of the frequency-adjustable FSS structure, a FSS sample was made using printed circuit boards (PCB). Figure 4 The FSS sample is shown in Figure 1. (a) Dielectric substrate layer (b) Double-layer unit board upper surface (c) Double-layer unit board lower surface; the material is the F4B-2 dielectric substrate on both sides. The FSS and antenna are made into an FP antenna structure and connected with nylon columns. Figure 5 This is a sample picture of the FP antenna.

[0066] The gain of the FSS-based FP antenna sample was measured using the free space measurement method in a microwave anechoic chamber.

[0067] Figure 6 This is the FP antenna test diagram. The instruments used include a vector network analyzer, transmitting and receiving antennas (8-12GHz). The prototype was tested and the results are as follows: Figure 7 The test results show that the antenna's operating frequency band ranges from 8.3 to 11.25 GHz, with a relative bandwidth of 29.5%, which is basically consistent with the simulation results. Figure 8The measured and simulated gains of the prototype antenna are shown, as well as the simulated gain of the feed antenna when PRS is not used. As shown in the figure, the measured 3dB gain bandwidth is Figure 7 The impedance bandwidth overlaps from 8.1 to 11.25 GHz, and the peak gain is 10.35 dBi, or 31.5%. The difference between the measured and simulated results is due to manufacturing and assembly errors in the antennas, as well as the actual tolerances of the measurement system. In addition, the gain comparison technique used to measure the antenna gain may introduce some error in the measured gain.

[0068] Study the radiation pattern, another important property of the antenna, and simulate and measure the E-plane and H-plane radiation patterns at 9.5, 10, and 10.5 GHz. Figure 9 Show, Figure 9 (a) is the 9.5 GHz E-plane radiation pattern, (b) is the 9.5 GHz H-plane radiation pattern, and (c) is the 10 GHz E-plane radiation pattern; (d) is the 10 GHz H-plane radiation pattern, (e) is the 10.5 GHz E-plane radiation pattern; and (f) is the 10.5 GHz H-plane radiation pattern. The broadband FP resonant cavity antenna produces directional radiation in both the E and H planes, achieving better directivity than a single antenna and thus achieving greater gain.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frequency selective surface unit with a normal reflection gradient phase, characterized by: including a dielectric substrate disposed on a top layer; The lower layer of the dielectric substrate is coupled to a double-layer unit board at a first preset distance; The double-layer unit plate includes a first unit plate and a second unit plate; The first unit board is arranged on an upper layer of the second unit board; The upper surface of the first unit plate is provided with a metal rectangular patch and an annular grid; The metal rectangular patch is arranged inside the annular grid; A cross-shaped metal patch is provided on the lower surface of the second unit board; The dielectric base plate is connected to the four corners of the double-layer unit plate through nylon columns.

2. The frequency selective surface unit with normal reflection gradient phase according to claim 1, characterized in that: The metal rectangular patch, the cross-shaped metal patch, and the annular grid are all made of copper.

3. The frequency selective surface unit with normal reflection gradient phase according to claim 1, characterized in that: The metal rectangular patch is spaced apart from the frame of the first unit board by a second preset distance.

4. The frequency selective surface unit with a normal reflection gradient phase according to claim 1, characterized in that: The dielectric substrate and the double-layer unit plate are both square.

5. The frequency selective surface unit with normal reflection gradient phase according to claim 1, characterized in that: The annular grid and the metal rectangular patch are square.

6. A frequency selective surface with a normal reflection gradient phase, characterized in that: The method comprises a plurality of frequency selective surface units according to any one of claims 1 to 5.

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