Frequency selective surface, device and communication equipment

Abstract

The invention discloses a frequency selection surface, a frequency selection device and communication equipment. The frequency selection surface comprises a plurality of unit structures which are arranged in an array; each unit structure comprises two layers of electrode plates arranged in a stacked mode and a dielectric layer located between the two layers of electrode plates. Each layer of electrode plate is provided with a hollow-out pattern, the hollow-out pattern is rotationally symmetrical along a first rotating shaft, the first rotating shaft passes through the center of the electrode plate and is perpendicular to the electrode plate, and the rotating angle is 90 degrees. Thus, by arranging the electrode plates with the 90-degree rotational symmetry structure, the frequency selective surface can respond to electromagnetic waves in various polarization directions, effective filtering can be carried out, and the filtering effect of the frequency selective surface is improved when the electromagnetic waves have various polarization directions.

Description

A frequency selective surface, device and communication equipment Technical Field

[0001] This invention relates to the field of electromagnetic wave technology, and more particularly to a frequency selective surface, device, and communication equipment. Background Technology

[0002] A frequency selective surface (FSS) is an array structure composed of multiple identical unit cells that can produce different responses to electromagnetic waves of different frequencies and polarizations, thus providing functions such as filtering and polarization selection. Existing FSSs primarily filter electromagnetic waves with a single polarization direction; therefore, their filtering effect deteriorates in scenarios where electromagnetic waves have multiple polarization directions.

[0003] Therefore, how to improve the filtering effect of frequency selective surfaces on electromagnetic waves with multiple polarization directions has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] This invention provides a frequency selective surface, a device, and a communication equipment to improve the filtering effect of the frequency selective surface when electromagnetic waves have multiple polarization directions.

[0005] In a first aspect, embodiments of the present invention provide a frequency selective surface, comprising: a plurality of unit structures arranged in an array;

[0006] The unit structure includes: two layers of electrode sheets stacked together, and a dielectric layer located between the two layers of electrode sheets; each layer of electrode sheet has a hollow pattern, the hollow pattern being rotationally symmetrical along a first rotation axis, the first rotation axis passing through the center of the electrode sheet and perpendicular to the electrode sheet, and the rotation angle being 90 degrees.

[0007] In a second aspect, embodiments of the present invention provide a frequency selection device, comprising: a frequency selection surface as described in the first aspect above, and a power supply connected to the frequency selection surface.

[0008] Thirdly, embodiments of the present invention provide a communication device, including the frequency selection device as described in the second aspect above.

[0009] The beneficial effects of this invention are as follows:

[0010] This invention provides a frequency selective surface, apparatus, and communication device, comprising: multiple unit structures arranged in an array; each unit structure includes: two layers of electrode sheets stacked together, and a dielectric layer located between the two electrode sheets; each electrode sheet has a perforated pattern, the perforated pattern being rotationally symmetrical about a first rotation axis, the first rotation axis passing through the center of the electrode sheet and perpendicular to the electrode sheet, with a rotation angle of 90 degrees. Thus, by setting electrode sheets with a 90-degree rotationally symmetrical structure, the frequency selective surface can respond to electromagnetic waves with various polarization directions, thereby enabling effective filtering. When electromagnetic waves have multiple polarization directions, the filtering effect of the frequency selective surface is improved. Attached Figure Description

[0011] Figure 1 is a top view of a frequency-selective surface provided in an embodiment of the present invention;

[0012] Figure 2 is a cross-sectional view of a frequency selective surface provided in an embodiment of the present invention;

[0013] Figure 3 is a schematic diagram of the structure of an electrode sheet provided in an embodiment of the present invention;

[0014] Figure 4 is a schematic diagram of the structure of two other electrode sheets provided in the embodiments of the present invention;

[0015] Figure 5 is a schematic diagram of the structure of a frequency selective surface provided in an embodiment of the present invention;

[0016] Figure 6 is a schematic diagram of another frequency selective surface provided in an embodiment of the present invention;

[0017] Figure 7 is a schematic diagram of the stacked two-layer electrode sheet arrangement provided in an embodiment of the present invention;

[0018] Figure 8 is a cross-sectional view of another frequency-selective surface provided in an embodiment of the present invention;

[0019] Figure 9 is the first simulation image of the frequency selection surface of the single-layer unit structure provided in the embodiment of the present invention;

[0020] Figure 10 is a second simulation image of the frequency selective surface of the single-layer unit structure provided in the embodiment of the present invention;

[0021] Figure 11 is the third simulation image of the frequency selection surface of the single-layer unit structure provided in the embodiment of the present invention;

[0022] Figure 12 is the first simulation diagram of the frequency selective surface of the double-layer unit structure provided in the embodiment of the present invention;

[0023] Figure 13 is a second simulation diagram of the frequency selective surface of the double-layer unit structure provided in the embodiment of the present invention;

[0024] Figure 14 is the third simulation diagram of the frequency selection surface of the double-layer unit structure provided in the embodiment of the present invention;

[0025] Figure 15 is a schematic diagram of a frequency selection device provided in an embodiment of the present invention;

[0026] Figure 16 is a schematic diagram of the structure of a communication device provided in an embodiment of the present invention. Detailed Implementation

[0027] The following detailed description, with reference to the accompanying drawings, provides a specific embodiment of a frequency selective surface, apparatus, and communication device provided by the present invention. It should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] This invention provides a frequency selective surface, as shown in Figures 1 and 2. Figure 1 is a top view of the frequency selective surface, and Figure 2 is a cross-sectional view of a unit structure 100 in Figure 1. The frequency selective surface includes a plurality of unit structures 100 arranged in an array.

[0029] The unit structure 100 includes: two layers of electrode sheets 101 stacked together, and a dielectric layer 102 located between the two layers of electrode sheets 101; each layer of electrode sheet 101 has a hollow pattern, the hollow pattern is rotationally symmetrical along a first rotation axis, the first rotation axis passes through the center of the electrode sheet 101 and is perpendicular to the electrode sheet 101, and the rotation angle is 90 degrees.

[0030] Thus, by setting an electrode plate with a 90-degree rotational symmetry structure, the frequency selective surface can respond to electromagnetic waves of various polarization directions, thereby enabling effective filtering. When electromagnetic waves have multiple polarization directions, the filtering effect of the frequency selective surface is improved.

[0031] The dielectric layer may be made of materials including but not limited to liquid crystal materials, ferroelectric materials, and other tunable dielectric materials. The specific materials used in the dielectric layer may be set according to actual needs and are not limited here.

[0032] It should be understood that the working principle of the frequency selective surface provided in this embodiment of the invention includes: when the dielectric constant of the dielectric layer is constant, the frequency selective surface can allow electromagnetic waves within a certain frequency range to be transmitted, while electromagnetic waves of other frequencies are reflected, thereby achieving a filtering function. The aforementioned certain frequency range can be called the passband of the frequency selective surface, and the center value of the passband can be called the center operating frequency. Further, by applying different voltages to the two stacked electrode sheets, an electric field is applied to the dielectric layer between the two electrode sheets. Since the dielectric layer is a tunable dielectric material, the electric field causes the dielectric constant of the dielectric layer to change, thereby the dielectric layer produces different responses to electromagnetic waves of different frequencies. When the dielectric constant is low, the center operating frequency of the frequency selective surface is high, and when the dielectric constant is high, the center operating frequency of the frequency selective surface is low. Thus, by changing the dielectric constant of the dielectric layer, the filtering function of electromagnetic waves of different frequencies is achieved.

[0033] In addition, as shown in Figure 2, the unit structure also includes a base layer 103 located on the side of each electrode sheet 101 facing away from the dielectric layer 102. The base layer 103 is made of materials including, but not limited to, low-loss dielectric materials such as polytetrafluoroethylene, polypropylene, and polystyrene, thereby reducing the influence of the base layer 103 on electromagnetic wave propagation. When fabricating the frequency selective surface, the electrode sheet 101 can be printed on the adjacent base layer 103, which facilitates the fabrication of the electrode sheet 101 and serves to encapsulate and protect the electrode sheet, improving the practicality of the frequency selective surface.

[0034] Optionally, as shown in Figure 3, which is a schematic diagram of the electrode sheet 101 viewed along the arrangement direction of the two layers of electrode sheets 101, the hollow pattern includes: multiple repeating patterns D, each repeating pattern D arranged in a rotating manner around a first rotation axis A. Each repeating pattern D includes a first segment D1 with its starting end located on the first rotation axis A, a second segment D2 with its starting end connected to the end of the first segment D1, and a third segment D3 with its starting end connected to the end of the second segment D2. The first segment D1 and the third segment D3 extend in opposite directions, and the second segment D2 extends perpendicularly to the first segment D1. Since the first rotation axis A is an axis perpendicular to the electrode sheet 101, it is represented by a point in Figure 3.

[0035] Thus, by forming a hollow pattern through multiple repeating patterns, and the hollow pattern having a 90-degree rotational symmetry structure, an electrode sheet with a 90-degree rotational symmetry structure can be formed, so that the frequency selective surface can respond to electromagnetic waves of various polarization directions, thereby enabling effective filtering. When electromagnetic waves have multiple polarization directions, the filtering effect of the frequency selective surface is improved.

[0036] Furthermore, as shown in Figure 3, the electrode sheet 101 also includes multiple sheet-like structures C, which are formed by a perforated pattern. This allows a large capacitance to be formed between the two stacked electrode sheets 101 through the sheet-like structures C. Additionally, due to the perforated pattern within the electrode sheet 101, a large inductance is also formed. Thus, the unit structure possesses both large capacitance and inductance. When an incident electromagnetic wave occurs, the capacitance and inductance in the unit structure will act as a resonant structure. Because the capacitance and inductance values ​​are large, the adjustable range is also large, thereby increasing the tunable range of the frequency selective surface and expanding its application range. On the other hand, when the required tunable range is fixed, a smaller unit structure can achieve the target tunable range, thus realizing a small-size design for the unit structure.

[0037] Of course, the hollow pattern on the electrode sheet 101 is not limited to the structure described above. It can also be other structures with 90-degree rotational symmetry, such as, but not limited to, electrode sheets 101 with the two hollow patterns shown in Figure 4. Similarly, the hollow patterns of the two structures in Figure 4 can also make the unit structure have a larger inductance and capacitance, thereby increasing the tunable range of the frequency selection surface. The specific structure of the hollow pattern can be set according to actual needs, and no specific limitation is made here.

[0038] Optionally, as shown in Figure 5, the electrode sheets 101 located in the same film layer in each unit structure are independent of each other. The electrode sheets 101 located in the same film layer are disposed on the same substrate layer 103. Thus, when power is supplied to each electrode sheet 101, the voltage of each electrode sheet 101 can be controlled separately, improving the control flexibility of the frequency selective surface.

[0039] Optionally, as shown in FIG5, the unit structure further includes at least one annular structure H disposed around the electrode sheet 101, and the annular structure H and the electrode sheet 101 are independent of each other. The annular structure H disposed on the same substrate layer 103 and the electrode sheet 101 are located in the same film layer.

[0040] Thus, by setting up a ring structure, the inductance of the unit structure can be adjusted through the ring structure, thereby making the filter edge steeper and improving the filtering effect of the frequency selective surface.

[0041] It should be understood that the filter edge can be interpreted as follows: For a frequency selective surface, its passband range is: frequencies greater than a and less than b. The transmittance of electromagnetic waves is higher in the range of frequencies greater than a and less than b, while the transmittance of electromagnetic waves at other frequencies is lower. Therefore, the filter edge has two sides, one near frequency a and the other near frequency b, thus the filter edge is steeper. This means that when the frequency of the electromagnetic wave changes near frequency a, the transmittance of the frequency selective surface changes faster, and / or, when the frequency of the electromagnetic wave changes near frequency b, the transmittance of the frequency selective surface changes faster. Therefore, by setting a ring structure, the filtering effect of the frequency selective surface can be improved.

[0042] Furthermore, as shown in Figure 5, there are multiple annular structures H, each independent of the others. Thus, by setting multiple independent annular structures H, some of the annular structures H can make one side of the filter edge steeper, and others can make the other side of the filter edge steeper, thereby further improving the filtering effect of the frequency selective surface.

[0043] Of course, only one ring structure can be set, which makes the filter edge on a certain side steeper, simplifies the structure of the frequency selective surface, reduces manufacturing costs, and improves the filtering effect of the frequency selective surface; or, the ring structure can be omitted to further simplify the structure of the frequency selective surface and reduce manufacturing costs.

[0044] Optionally, as shown in Figure 6, the electrode sheets 101 located in the same film layer in each unit structure are interconnected. In this way, only one control line is needed to power the electrode sheets, eliminating the need for additional lines, avoiding the impact of multiple lines on the filtering performance of the frequency selective surface, and improving the filtering effect of the frequency selective surface.

[0045] Of course, when connecting the electrode sheets in the same film layer, the electrode sheets in the same film layer can be an integral structure, which makes the connection more reliable; or, the electrode sheets in the same film layer can be connected by setting a connection structure. The specific connection method of the electrode sheets in the same film layer can be set according to actual needs and is not limited here.

[0046] Optionally, in a frequency selective surface, the electrode plates of one layer of the same film can be connected, and the electrode plates of another layer of the same film can be connected. This improves the flexibility of the frequency selective surface setup.

[0047] In addition, for each electrode sheet in the same film layer, some electrode sheets can be connected to each other, thereby realizing the partitioning of the frequency selective surface, thus realizing the control of the voltage of each partition, and filtering of electromagnetic waves of different frequencies in each partition, thereby improving the application range of the frequency selective surface.

[0048] Optionally, as shown in Figure 7, which is a schematic diagram of two electrode sheets 101 viewed from the dielectric layer, in the unit structure, one electrode sheet 101 is rotated 180 degrees along the second rotation axis and then coincides with the hollow pattern of the other electrode sheet 101. The second rotation axis passes through the center of the electrode sheet 101 and is parallel to the electrode sheet 101. The 180-degree rotation of the electrode sheet 101 along the second rotation axis can also be considered as flipping the electrode sheet 101 by 180 degrees.

[0049] Thus, by rotating one electrode plate 180 degrees along the second rotation axis to overlap with the hollow pattern of the other electrode plate, and arranging the two hollow patterns in an anti-spiral spiral pattern, the two stacked electrode plates can form a larger inductance, thereby increasing the tunable range of the frequency selective surface. Furthermore, the sheet-like structures within the two stacked electrode plates can also form a larger capacitance, further increasing the tunable range of the frequency selective surface.

[0050] Optionally, the size of the unit structure is one-tenth of the target wavelength, where the target wavelength is the wavelength of the electromagnetic wave within the passband of the frequency-selective surface. Specifically, when the unit structure is square, its size can be the side length of the square; when it is circular, its size can be the diameter of the circle; and when it has other irregular shapes, its size can be the side length of the smallest square or the diameter of the smallest circle enclosing the corresponding shape. The shape of the unit structure can be understood as the orthographic projection shape of the dielectric layer in the unit structure onto the substrate layer.

[0051] Thus, by setting smaller unit structure sizes, more unit structures can be set when the size of the frequency selective surface is fixed, thereby improving the filtering effect of the frequency selective surface. In addition, the miniaturization of the unit structure can also improve the angular stability of the frequency selective surface, so that electromagnetic waves can maintain good filtering performance when incident on the frequency selective surface from various angles.

[0052] It should be understood that the operating frequency will vary depending on the filtering requirements. This will require the size of the hollow pattern and the size of the ring structure in the electrode layer to be set accordingly to meet the filtering needs of the electromagnetic pen at the corresponding frequency. Therefore, the size of the hollow pattern and the size of the ring structure in the electrode layer need to be adjusted according to the actual operating frequency, without making specific limitations here.

[0053] Optionally, as shown in Figure 8, the multiple unit structures 100 arranged in an array are distributed in multiple layers. The number of layers in the unit structure includes, but is not limited to, two, three, or more layers, which can be set according to actual needs.

[0054] Thus, by adopting a multi-layered distributed unit structure, not only can the filtering effect of the frequency selective surface be further improved, but the transmission poles of the frequency selective surface in the passband can also be increased, thereby widening the passband bandwidth of the frequency selective surface and improving the practicality of the frequency selective surface.

[0055] It should be understood that when the unit structure is distributed in multiple layers, the dimensions of each layer of unit structure are the same, and each layer of unit structure is independent of each other; the spacing between unit structures can be, but is not limited to, set to one-quarter of the target wavelength, thereby reducing the loss of electromagnetic waves in the frequency selective surface and improving the reliability of the frequency selective surface.

[0056] The frequency selection surface provided in this embodiment of the invention will be explained below with reference to specific embodiments, in which the dielectric layer material is liquid crystal material, the electrode sheet morphology is as shown in Figure 3, and the two stacked electrode sheets are arranged in the manner shown in Figure 7.

[0057] It should be understood that when describing the filtering performance of a frequency selective surface, the electromagnetic wave incident on the frequency selective surface is generally used as a reference. The intensity of the transmitted electromagnetic wave is measured, and the filtering effect can be described in decibels. When the decibel value is -1dB, the intensity of the electromagnetic wave after passing through the frequency selective surface is about 80% of the incident intensity. When the decibel value is -0.5dB, the intensity of the electromagnetic wave after passing through the frequency selective surface is about 90% of the incident intensity. Therefore, the frequency range with an intensity greater than -1dB or greater than -0.5dB is generally regarded as the passband of the frequency selective surface.

[0058] As shown in Figure 9, this is a simulation diagram of the tuning effect of a frequency selective surface with a single-layer unit structure. Curves 1, 2, and 3 in Figure 9 represent the transmission intensity curves when different electric fields are applied to the dielectric layer. The electric field strengths corresponding to curves 1, 2, and 3 gradually increase. Curve 1 corresponds to a zero bias dielectric layer, while curve 3 corresponds to a saturation bias dielectric layer. Curves 4, 5, and 6 represent the reflection intensity curves corresponding to curves 1, 2, and 3. Figure 9 shows that as the applied electric field strength increases, the transmission peak of the frequency selective surface gradually shifts to lower frequencies, and the corresponding reflection peak also shifts to lower frequencies. This is mainly because the dielectric constant of the dielectric layer increases with increasing electric field strength, causing the passband of the frequency selective surface to shift to lower frequencies. Furthermore, the passband bandwidth of this frequency selective surface is approximately 0.2 GHz, and the center operating frequency can be continuously tuned from 9.8 GHz to 8.8 GHz, achieving a tuning rate of 10.2%, thus realizing a relatively wide tuning range.

[0059] As shown in Figure 10, this figure represents a simulation of the angular stability of a frequency-selective surface with a single-layer unit structure when the incident electromagnetic wave is TE-polarized. Figure 10 shows a convex transmission peak and a corresponding concave reflection peak. The different curves in Figure 10 represent TE-polarized electromagnetic waves incident at different angles on the frequency-selective surface, ranging from 0 to 70 degrees. As can be seen from Figure 10, the simulation curves of TE-polarized electromagnetic waves incident at various angles almost overlap. This indicates that for TE-polarized electromagnetic waves, the filtering performance of this frequency-selective surface remains stable at all incident angles, and the resonant frequency hardly shifts, achieving high angular stability.

[0060] As shown in Figure 11, this figure represents a simulation of the angular stability of a frequency-selective surface with a single-layer unit structure when the incident electromagnetic wave is TM-polarized. Figure 11 shows a convex transmission peak and a corresponding concave reflection peak. The different curves in Figure 11 represent TM-polarized electromagnetic waves incident at different angles on the frequency-selective surface, with the angle range from 0 to 70 degrees. Comparing Figure 10 and Figure 11, it can be seen that the simulation curves of TM-polarized electromagnetic waves incident at various angles have poor overlap compared to the simulation curves of TE-polarized electromagnetic waves. However, within the passband of the frequency selection module, i.e., at the top of the transmission peak, the overlap of the simulation curves remains high. This indicates that for TM-polarized electromagnetic waves, the resonant frequency of this frequency-selective surface hardly shifts, thus achieving high angular stability.

[0061] Furthermore, combining Figures 10 and 11, it can be seen that the passband bandwidth, i.e., the center frequency, of this frequency-selective surface remains almost unchanged for both TE-polarized and TM-polarized electromagnetic waves. This indicates that the frequency-selective surface can filter both TE-polarized and TM-polarized electromagnetic waves with almost no change in filtering effect. Moreover, since the polarization directions of TE-polarized and TM-polarized electromagnetic waves are perpendicular to each other, based on the fact that this frequency-selective surface can effectively filter electromagnetic waves with two mutually perpendicular polarization directions, it can be foreseen that this frequency-selective surface can effectively filter electromagnetic waves with any other polarization direction.

[0062] As shown in Figure 12, Figure 12 is a simulation diagram of the frequency selective surface tuning effect with a double-layer unit structure. Curves 1, 2 and 3 in Figure 12 are the transmission intensity curves when different electric fields are applied to the dielectric layer. The electric field intensity corresponding to curves 1, 2 and 3 gradually increases. The dielectric layer corresponding to curve 1 is at zero bias voltage, and the dielectric layer corresponding to curve 3 is at saturation bias voltage. As shown in Figure 12, as the applied electric field strength increases, the transmission peak of the frequency selective surface with a double-layer unit structure gradually shifts to lower frequencies. Compared to the frequency selective surface with a single-layer unit structure (as shown in Figure 9), the filtering edge of the transmission peak in Figure 12 is steeper, indicating that the filtering effect of the frequency selective surface with a double-layer unit structure is improved. In addition, as shown in Figure 12, the center operating frequency of this frequency selective surface can be continuously tuned from 10.2 GHz to 9.2 GHz, with a passband bandwidth of approximately 0.8 GHz. Compared to the frequency selective surface with a single-layer unit structure (as shown in Figure 9), the frequency selective surface with a double-layer unit structure can achieve a wider passband bandwidth, thus broadening the application range of the frequency selective surface.

[0063] As shown in Figure 13, this figure represents a simulation of the angular stability of a frequency-selective surface with a two-layer unit structure when the incident electromagnetic wave is TE-polarized. Different curves in Figure 13 represent TE-polarized electromagnetic waves incident at different angles on the frequency-selective surface, ranging from 0 to 70 degrees. As can be seen from Figure 13, the simulation curves of TE-polarized electromagnetic waves incident at various angles almost overlap. This indicates that for TE-polarized electromagnetic waves, the filtering performance of the frequency-selective surface with a two-layer unit structure remains stable at all incident angles, and the resonant frequency hardly shifts, achieving high angular stability.

[0064] As shown in Figure 14, this is a simulation diagram of the angular stability of a frequency selective surface with a double-layer unit structure when the incident electromagnetic wave is a TM-polarized electromagnetic wave. Different curves in Figure 13 represent TM-polarized electromagnetic waves incident at different angles on the frequency selective surface, ranging from 0 to 70 degrees. Comparing Figures 13 and 14, it can be seen that, similar to a frequency selective surface with a single-layer unit structure, the resonant frequency of the frequency selective surface with a double-layer unit structure remains almost unchanged for TM-polarized electromagnetic waves, achieving high angular stability. Furthermore, the frequency selective surface with a double-layer unit structure can filter both TE-polarized and TM-polarized electromagnetic waves with almost no change in filtering effect. Therefore, it can be predicted that for a frequency selective surface with a double-layer unit structure, electromagnetic waves of any other polarization direction can be effectively filtered.

[0065] In summary, both single-layer and double-layer unit structures of frequency selective surfaces can filter electromagnetic waves of various polarization directions with high angular stability and a large tuning range. Compared with single-layer unit structures, the passband bandwidth of the double-layer unit structure is significantly improved.

[0066] Of course, other dielectric materials and electrode sheets with other structures and arrangements can also achieve frequency-selective surfaces with similar performance, which will not be described in detail here.

[0067] Based on the same inventive concept, this invention also provides a frequency selection device. The implementation principle of this frequency selection device is similar to that of the aforementioned frequency selection surface. The specific implementation of this frequency selection device can be found in the aforementioned embodiments of the frequency selection surface, and the repeated parts will not be described again.

[0068] Specifically, an embodiment of the present invention provides a frequency selection device, as shown in FIG15, comprising: a frequency selection surface 1501 as described above, and a power supply 1502 connected to the frequency selection surface 1501. The frequency selection device can be, but is not limited to, a radome, electromagnetic protection for communication equipment, or a stealth device for aircraft. Thus, the power supply 1502 applies a voltage to the two layers of electrodes stacked in the frequency selection surface 1501, thereby applying an electric field to the dielectric layer, causing a change in the dielectric constant of the dielectric layer, thereby realizing the filtering function of the frequency selection surface.

[0069] Based on the same inventive concept, this invention also provides a communication device. The implementation principle of this communication device is similar to that of the aforementioned frequency selective surface. The specific implementation method of this communication device can be found in the aforementioned embodiments of the frequency selective surface, and the repeated parts will not be described again.

[0070] Specifically, an embodiment of the present invention provides a communication device, as shown in FIG16, including a frequency selection device 1601 as described above. The frequency selection device 1601 can be installed at the input and output electromagnetic wave locations of the communication device to filter the electromagnetic waves and maintain the normal operation of the communication device.

[0071] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A frequency-selective surface, characterized in that, include: Multiple unit structures arranged in an array; The unit structure includes: two layers of electrode sheets stacked together, and a dielectric layer located between the two layers of electrode sheets; Each layer of the electrode sheet has a hollow pattern, which is rotationally symmetrical along a first rotation axis. The first rotation axis passes through the center of the electrode sheet and is perpendicular to the electrode sheet, with a rotation angle of 90 degrees.

2. The frequency selective surface as described in claim 1, characterized in that, Each electrode sheet located in the same film layer in each of the unit structures is independent of the others.

3. The frequency selective surface as described in claim 2, characterized in that, The unit structure further includes at least one annular structure disposed around the electrode sheet, and the annular structure is independent of the electrode sheet.

4. The frequency selective surface as described in claim 3, characterized in that, There are multiple ring structures, and each ring structure is independent of the others.

5. The frequency selective surface as described in claim 1, characterized in that, The electrode sheets located in the same film layer in each of the unit structures are interconnected.

6. The frequency selective surface as described in claim 1, characterized in that, In the unit structure, one electrode plate rotates 180 degrees along the second rotation axis and then overlaps with the hollow pattern of another electrode plate. The second rotation axis passes through the center of the electrode plate and is parallel to the electrode plate.

7. The frequency selective surface as described in claim 6, characterized in that, The hollow pattern includes: multiple repeating patterns, each repeating pattern is arranged to rotate around the first rotation axis, each repeating pattern includes a first segment with its starting end located on the first rotation axis, a second segment with its starting end connected to the end of the first segment, and a third segment with its starting end connected to the end of the second segment; the first segment and the third segment extend in opposite directions, and the second segment extends perpendicularly to the first segment.

8. The frequency selective surface as claimed in claim 1, characterized in that, The size of the unit structure is one-tenth of the target wavelength, which is the wavelength of the electromagnetic wave within the passband of the frequency-selective surface.

9. The frequency selective surface as described in any one of claims 1-8, characterized in that, The multiple unit structures arranged in an array are distributed in multiple layers.

10. A frequency selection device, characterized in that, include: The frequency selective surface as described in any one of claims 1-9, and the power supply connected to the frequency selective surface.

11. A communication device, characterized in that, Includes the frequency selection device as described in claim 10.

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