Tunable wave absorber

Abstract

The invention provides a tunable wave absorber, and relates to the technical field of electromagnetic devices. The tunable wave absorber comprises a frequency selection surface layer, a dielectric substrate, a microwave diode, a conductive piece and a metal grounding plate, the frequency selection surface layer and the metal grounding plate are respectively arranged on two opposite surfaces of the dielectric substrate; the frequency selection surface layer comprises a central metal sheet and a plurality of frequency selection units, and the plurality of frequency selection units are periodically arranged around the central metal sheet; the microwave diode is respectively connected with the central metal sheet and the plurality of frequency selection units, the central metal sheet is connected with the metal grounding plate through the conductive piece, and the plurality of frequency selection units and the metal grounding plate are used for being connected with an external power supply. And the external power supply is used for providing reverse bias voltage for the microwave diode. According to the invention, tuning of the wave absorbing frequency band of the wave absorber is realized, the wave absorbing frequency band of the wave absorber is increased, and the wave absorbing efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electromagnetic devices, and in particular to a tunable absorber. Background Art

[0002] Frequency Selective Surface (FS) is a special electromagnetic material structure, which is composed of a series of regularly arranged conductive elements (usually metals). These conductive elements are designed in shape and arrangement so that the FSS has the characteristics of reflection, transmission, and absorption for electromagnetic waves of different frequencies. Since FSS can achieve precise control of the specific frequency, polarization, and propagation direction of electromagnetic waves, it is widely used in electromagnetic devices such as absorbers, filters, and isolators that require precise control of the frequency of electromagnetic waves.

[0003] Among them, the absorber is a device that can absorb electromagnetic waves and convert them into other forms of energy. However, the current absorbers based on frequency selective surfaces can only absorb electromagnetic waves of a fixed frequency, and have a low efficiency in absorbing electromagnetic waves. Summary of the invention

[0004] In view of this, the present application aims to propose a tunable absorber to solve the problem that the current absorber based on frequency selective surface can only absorb electromagnetic waves of fixed frequency and has low electromagnetic wave absorption efficiency. To achieve the above purpose, the technical solution of the present application is implemented as follows:

[0005] According to the first aspect of the present application, the present application embodiment provides a tunable absorber, the tunable absorber comprising:

[0006] Frequency selective surface layer, dielectric substrate, microwave diode, conductive member and metal ground plate;

[0007] The frequency selective surface layer and the metal ground plate are respectively arranged on two opposite surfaces of the dielectric substrate;

[0008] The frequency selective surface layer comprises a central metal sheet and a plurality of frequency selective units, wherein the plurality of frequency selective units are periodically arranged around the central metal sheet;

[0009] The microwave diode is connected to the central metal sheet and the multiple frequency selection units respectively, the central metal sheet is connected to the metal ground plate through the conductive member, the multiple frequency selection units and the metal ground plate are both used to be connected to an external power supply, and the external power supply is used to provide a reverse bias voltage to the microwave diode.

[0010] Optionally, there are multiple microwave diodes, and they correspond one-to-one to the frequency selection units;

[0011] Each of the microwave diodes is connected to the central metal sheet and to the corresponding frequency selection unit.

[0012] Optionally, there is a fine gap between each of the frequency selection units and the central metal sheet, and each of the microwave diodes is arranged in the fine gap and is respectively connected to the central metal sheet and the corresponding frequency selection unit.

[0013] Optionally, the tunable absorber further comprises: a plurality of metal thin strips;

[0014] Each of the metal strips is connected to two adjacent frequency selection units to connect the multiple frequency selection units with a power supply terminal, and the power supply terminal is used to connect the external power supply.

[0015] Optionally, the center point of the central metal sheet is located at the center of the frequency selective surface layer and on the central axis of the tunable absorber.

[0016] Optionally, a central axis of the conductive member coincides with a central axis of the tunable absorber.

[0017] Optionally, each of the frequency selection units is a metal sheet of the same shape, and the multiple frequency selection units are arranged in a symmetrical structure.

[0018] Optionally, the frequency selective surface layer is a centrally symmetrical pattern.

[0019] Optionally, the dielectric substrate is square, and the frequency selective surface layer includes four frequency selective units;

[0020] The central metal sheet is a regular hexagonal metal sheet, each of the frequency selection units is a square metal sheet with a same shape, each of the frequency selection units is respectively arranged at the four corners of the dielectric substrate, and the two non-missing sides of the square metal sheet with a missing corner are respectively overlapped with the two sides of the dielectric substrate, and the missing side of the square metal sheet with a missing corner is connected to the central metal sheet through the microwave diode.

[0021] Optionally, the side length of the central metal sheet is equal to the side length of the frequency selection unit with a missing corner, and is smaller than the side length of the frequency selection unit without a missing corner.

[0022] According to a second aspect of the present application, an electronic device is provided, wherein the electronic device comprises the tunable absorber described in any one of the first aspects.

[0023] With respect to current technologies, this application has the following advantages:

[0024] In an embodiment of the present application, the tunable absorber includes: a frequency selective surface layer, a dielectric substrate, a microwave diode, a conductive member, and a metal ground plate. The frequency selective surface layer and the metal ground plate are respectively arranged on two opposite sides of the dielectric substrate. The frequency selective surface layer includes a central metal sheet, and a plurality of frequency selective units periodically arranged around the central metal sheet.

[0025] Among them, the microwave diode is respectively connected to the central metal sheet and multiple frequency selection units, and the central metal sheet is connected to the metal ground plate through a conductive member. In this way, the external power supply connected to the multiple frequency selection units and the metal ground plate can provide a reverse bias voltage to the microwave diode through the central metal sheet and the conductive member. And because the reverse bias voltage of the microwave diode can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, the adjustable absorber in the technical solution of the present application can achieve tuning of its absorbing frequency band by adjusting the size of the reverse bias voltage of the microwave diode, increase the absorbing frequency band of the absorber, and improve the absorbing efficiency to a certain extent.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0028] Figure 1 An exploded view of a tunable absorber provided in an embodiment of the present application.

[0029] Figure 2 A schematic diagram of the structure of a tunable absorber provided in an embodiment of the present application.

[0030] Figure 3 A schematic diagram of the structure of another tunable absorber provided in an embodiment of the present application.

[0031] Figure 4 A schematic diagram of the structure of another tunable absorber provided in an embodiment of the present application.

[0032] Figure 5A schematic diagram of the structure of another tunable absorber provided in an embodiment of the present application.

[0033] Figure 6 A schematic diagram of the dimensions of a tunable absorber provided in an embodiment of the present application.

[0034] Figure 7 A schematic diagram of a change in reflection coefficient provided in an embodiment of the present application;

[0035] Figure 8 A schematic diagram of the change of wave absorption rate provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] Frequency Selective Surface (FSS) is a special electromagnetic material structure, which is composed of a series of regularly arranged conductive elements (usually metals). These conductive elements are designed through shape and arrangement so that the frequency selective surface has the characteristics of reflection, transmission, and absorption for electromagnetic waves of different frequencies. Since the frequency selective surface can achieve precise control of the specific frequency, polarization and propagation direction of electromagnetic waves. Therefore, it is widely used in electromagnetic devices such as absorbers, filters and isolators that require precise control of the frequency of electromagnetic waves, so as to adapt to the scenarios of other electromagnetic devices that require precise control of the frequency of electromagnetic waves, such as antenna systems, radar systems, wireless communication systems, etc.

[0038] The working principle of frequency selective surface is based on the periodic structure of conductive elements, which selectively responds to the frequency of incident electromagnetic waves. Specifically, when electromagnetic waves interact with the frequency selective surface, the periodic structure of the frequency selective surface causes the wavelength of a specific frequency to match its structural period, thereby causing a significant transmission effect or reflection effect.

[0039] Among them, the absorber is a device that can absorb electromagnetic waves and convert them into other forms of energy. The current working modes of the absorber include single-band mode, dual-band mode and broadband mode. A single-band mode absorber refers to an absorber with only one absorbing frequency band. The absorber can only absorb electromagnetic waves of one frequency band for energy conversion. A dual-band mode absorber refers to an absorber with two different absorbing frequency bands. The absorber can absorb electromagnetic waves of two different frequency bands at the same time for energy conversion. A dual-band mode absorber refers to an absorber with a wider absorbing frequency band. The absorber can absorb electromagnetic waves of a wider frequency band for energy conversion.

[0040] However, the current wave absorbers based on frequency selective surfaces can only absorb electromagnetic waves of fixed frequencies, and their wave absorption frequency band is not adjustable. Therefore, the wave absorption efficiency of the wave absorber is limited to a certain extent, resulting in the problem of low electromagnetic wave absorption efficiency of the wave absorber.

[0041] Please refer to Figure 1 and Figure 2 , which respectively show the structural schematic diagrams of two tunable absorbers provided in the embodiments of the present application. The tunable absorber, which can also be called an adjustable absorber based on a microwave diode and a frequency selective surface, can solve the above-mentioned technical problems to a certain extent.

[0042] in, Figure 1 An exploded view of a tunable absorber provided in an embodiment of the present application. Figure 2 A schematic diagram of the structure of a tunable absorber provided in an embodiment of the present application. Figure 1 and Figure 2 As shown, the tunable absorber 1 comprises:

[0043] The frequency selective surface layer 11 , the dielectric substrate 12 , the microwave diode 13 , the conductive member 14 and the metal grounding plate 15 .

[0044] Among them, the frequency selective surface layer 11 and the metal grounding plate 15 are respectively arranged on two opposite sides of the dielectric substrate 12. The frequency selective surface layer 11 includes a central metal sheet 111 and a plurality of frequency selective units 112. The plurality of frequency selective units 112 are periodically arranged around the central metal sheet 111. Optionally, the frequency selective surface layer 11 can have absorption characteristics for electromagnetic waves of at least one frequency band based on the shape and arrangement of the central metal sheet 111 and the plurality of frequency selective units 112. That is, the frequency selective surface layer 11 can absorb electromagnetic waves of at least one frequency band at the same time. Accordingly, the tunable absorber 1 of the present application can have at least one absorbing frequency band. As an example, the frequency selective surface layer 11 can have absorption characteristics for electromagnetic waves of two frequency bands, so that the tunable absorber 1 of the present application can have two absorbing frequency bands. As another example, the frequency selective surface layer 11 can have absorption characteristics for electromagnetic waves of four frequency bands, so that the tunable absorber 1 of the present application can have four absorbing frequency bands.

[0045] The microwave diode 13 is respectively connected to the central metal sheet 111 and the plurality of frequency selection units 112. The central metal sheet 111 is connected to the metal grounding plate 15 through the conductive member 14.

[0046] The multiple frequency selection units 112 and the metal ground plate 15 are used to connect to the external power supply ( Figure 1 and Figure 2 The external power supply is used to provide a reverse bias voltage to the microwave diode 13. Wherein, when the external power supply is powered, the external power supply sequentially forms a conductive loop with the frequency selection unit 112, the microwave diode 13, the central metal sheet 111, the conductive member 14 and the metal grounding plate 15.

[0047] In one example, the positive electrode of the microwave diode 13 is connected to the plurality of frequency selection units 112. The negative electrode of the microwave diode 13 is connected to the central metal sheet 111. Figure 3 As shown, the external power supply can provide a reverse voltage V- to the multiple frequency selection units 112, so as to provide the reverse voltage V- to the positive electrode of the microwave diode 13 through the frequency selection unit 112. In addition, the external power supply provides a forward voltage V+ to the metal ground plate 15, so as to provide the forward voltage V+ to the negative electrode of the microwave diode 13 through the metal ground plate 15, the conductive member 14 and the central metal sheet 111, so as to apply a reverse bias voltage to the microwave diode 13. That is, the external power supply can apply a reverse bias voltage to the microwave diode 13 by providing a reverse voltage V- to the upper surface of the tunable absorber 1 (i.e., the surface where the frequency selection surface layer 11 is located) and providing a forward voltage V+ to the lower surface of the tunable absorber 1 (i.e., the surface where the metal ground plate 15 is located).

[0048] In another example, the cathode of the microwave diode 13 is connected to a plurality of frequency selection units 112. The anode of the microwave diode 13 is connected to the central metal sheet 111. The external power supply can provide a forward voltage V+ to the plurality of frequency selection units 112, so as to provide a forward voltage V+ to the cathode of the microwave diode 13 through the frequency selection unit 112. In addition, the external power supply provides a reverse voltage V- to the metal ground plate 15, so as to provide a reverse voltage V- to the anode of the microwave diode 13 through the metal ground plate 15, the conductive member 14 and the central metal sheet 111, so as to apply a reverse bias voltage to the microwave diode 13. That is, the external power supply can apply a reverse bias voltage to the microwave diode 13 by providing a forward voltage V+ to the upper surface of the tunable absorber 1 (i.e., the surface where the frequency selection surface layer 11 is located) and providing a reverse voltage V- to the lower surface of the tunable absorber 1 (i.e., the surface where the metal ground plate 15 is located).

[0049] In the embodiment of the present application, the microwave diode 13 has an equivalent capacitance characteristic. The equivalent capacitance characteristic refers to that the size of the equivalent capacitance of the microwave diode 13 changes with the reverse bias voltage of the microwave diode 13. Specifically, when the microwave diode 13 is in a reverse bias state, its external electric field is consistent with the direction of the internal electric field in its space charge region, so that the width of its space charge region increases. As the reverse bias voltage increases, the width of the space charge region will gradually increase. The size of the equivalent capacitance of the microwave diode 13 is inversely proportional to the width of its space charge region. Therefore, as the reverse bias voltage increases, the equivalent capacitance of the microwave diode 13 will decrease. Conversely, as the reverse bias voltage decreases, the equivalent capacitance of the microwave diode 13 will increase.

[0050] Moreover, the wave absorbing efficiency of the wave absorber based on the frequency selective surface can be represented by Formula 1. Formula 1 satisfies: Absord = 1 - |S 11 | 2 -|S 21 | 2 In formula 1, Absord represents the absorbing efficiency of the absorber based on the frequency selective surface. 11 S represents the reflection coefficient of the absorber based on the frequency selective surface. 21 The absorber provided by the technical solution of the present application has a bottom layer using a metal ground plate 15, and the absorption rate of the metal ground plate 15 to electromagnetic waves is almost 0. Therefore, the absorption coefficient S of the adjustable absorber provided by the technical solution of the present application is 21 It can be considered as 0, that is, S 21 =0. Thus, the adjustable absorber provided by the technical solution of the present application has an absorption efficiency that can be represented by Formula 2. Formula 2 satisfies: Absord = 1 - |S 11 | 2In formula 2, Absord represents the absorbing efficiency of the adjustable absorber. 11 It represents the reflection coefficient of the adjustable absorber provided by the technical solution of the present application.

[0051] It is not difficult to see from Formula 2 that the absorbing frequency of the adjustable absorber provided in the embodiment of the present application is mainly affected by its reflection coefficient. The magnitude of the reflection coefficient of the absorber based on the frequency selective surface will be affected by the current direction and magnitude of the frequency selective surface, and the current direction and magnitude of the bottom layer. For the adjustable absorber provided in the embodiment of the present application, the magnitude of the reflection coefficient of the adjustable absorber will be affected by the direction and magnitude of the surface current of the frequency selective surface layer 11 and the surface current and magnitude of the metal grounding plate 15.

[0052] As mentioned above, the current conduction path of the adjustable absorber of the embodiment of the present application is: the frequency selection unit 112, the microwave diode 13, the central metal sheet 111, the conductive member 14 and the metal grounding plate 15. Therefore, the direction of the current on the frequency selection unit 112 and the central metal sheet 111 is opposite to the direction of the current on the metal grounding plate 15. This opposite current can constitute a magnetic dipole, so that the frequency selection unit 112 and the metal grounding plate 15 resonate. Under the action of resonance, the electromagnetic wave energy received by the adjustable absorber is lost and then forms an absorption phenomenon. In addition, since the current of the adjustable absorber of the embodiment of the present application is mainly concentrated in the microwave diode 13. The equivalent capacitance of the microwave diode 13 can change with the change of the reverse bias voltage, and the current size changes with the change of the equivalent capacitance size. Therefore, the current of the absorber can change with the change of the reverse bias voltage of the microwave diode 13. Therefore, the reflection coefficient of the absorber is affected by the reverse bias voltage of the microwave diode 13 because the current is affected by the reverse bias voltage of the microwave diode 13, and is also affected by the reverse bias voltage of the microwave diode 13. Furthermore, since the current of the absorber will also affect the absorbing frequency band of the absorber, the reverse bias voltage of the microwave diode 13 affects the current of the absorber, so that the reverse bias voltage of the microwave diode 13 also affects the absorbing frequency band of the absorber. That is, when the reverse bias voltage of the microwave diode 13 is adjusted, the equivalent capacitance of the microwave diode 13 is adjusted accordingly, so that the current of the absorber is adjusted accordingly, and then the absorbing frequency band of the absorber can be adjusted, thereby realizing the tuning of the absorbing frequency of the absorber.

[0053] In an embodiment of the present application, the tunable absorber includes: a frequency selective surface layer, a dielectric substrate, a microwave diode, a conductive member, and a metal ground plate. The frequency selective surface layer and the metal ground plate are respectively arranged on two opposite sides of the dielectric substrate. The frequency selective surface layer includes a central metal sheet, and a plurality of frequency selective units periodically arranged around the central metal sheet.

[0054] Among them, the microwave diode is respectively connected to the central metal sheet and multiple frequency selection units, and the central metal sheet is connected to the metal ground plate through a conductive member. In this way, the external power supply connected to the multiple frequency selection units and the metal ground plate can provide a reverse bias voltage to the microwave diode through the central metal sheet and the conductive member. And because the reverse bias voltage of the microwave diode can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, the adjustable absorber in the technical solution of the present application can achieve tuning of its absorbing frequency band by adjusting the size of the reverse bias voltage of the microwave diode, increase the absorbing frequency band of the absorber, and improve the absorbing efficiency to a certain extent.

[0055] Alternatively, if Figure 1 and Figure 2 As shown, the number of microwave diodes 13 can be multiple, and they correspond to the frequency selection units 112 one by one. Each microwave diode 13 is connected to the central metal sheet 111 and to the corresponding frequency selection unit 112. One pole of each microwave diode 13 is used to receive the voltage conducted by its corresponding frequency selection unit 112, and the other pole of each microwave diode 13 receives the voltage transmitted by the metal ground plate 15 through the conductive member 14 to receive the reverse bias voltage. For example, the two ends of the microwave diode 13 can be welded to the central metal sheet 111 and the frequency selection unit 112 respectively to achieve conduction among the three.

[0056] Alternatively, please refer to Figure 4 , which shows a schematic diagram of the structure of the tunable absorber provided in an embodiment of the present application. Figure 4 FIG. 1 is a top view of the tunable absorber 1. Figure 4 As shown, there is a slit S between each frequency selection unit 112 and the central metal sheet 111. Each microwave diode 13 is disposed in the slit S and is respectively connected to the central metal sheet 111 and the corresponding frequency selection unit 112. That is, each microwave diode 13 can be embedded in the slit S between the central metal sheet 111 and the corresponding frequency selection unit 112.

[0057] It should be noted that Figure 4 Take the tunable absorber 1 including four microwave diodes 13 and four frequency selection units 112 as an example, and use a dotted frame to schematically mark the slit S. And, Figure 4 The shapes and arrangement of the frequency selection units 112 and the central metal sheet 111 do not limit the shapes and arrangement of the frequency selection units 112 and the central metal sheet 111 in the frequency selection surface layer 11 of the embodiment of the present application.

[0058] In the embodiment of the present application, when the tunable absorber 1 includes multiple microwave diodes 13, the multiple microwave diodes 13 need to simultaneously receive reverse bias voltages of equal magnitude so that the equivalent capacitances of the multiple microwave diodes 13 maintain the same change, maintain the current distribution on the frequency selective surface layer 11, the conductive member 14 and the metal ground plate 15, and ensure the working characteristics of the frequency selective surface layer 11.

[0059] In an optional case, each frequency selection unit 112 in the tunable absorber 1 is connected to an external power supply, respectively. The external power supply is used to provide a reverse bias voltage of the microwave diode 13 to each frequency selection unit 112 at the same time.

[0060] In another optional case, a plurality of frequency selection units 112 in the tunable absorber 1 can be connected in series and then connected to an external power supply. The external power supply is used to provide a reverse bias voltage of the microwave diode 13 to the series line of the plurality of frequency selection units 112.

[0061] Alternatively, if Figure 1 , Figure 2 and Figure 3 As shown, the tunable absorber 1 also includes: a plurality of metal strips 16. The metal strips 16 are also called edge metal strips 16. Each metal strip 16 is connected to two adjacent frequency selection units 112 to connect the plurality of frequency selection units 112 with a power supply terminal (not shown in the figure), and the power supply terminal is used to connect an external power supply. In this way, the plurality of frequency selection units 112 can be connected in series to the external power supply through the metal strips 16, and the current of the tunable absorber 1 will be mainly concentrated in the metal strips 16 in addition to the microwave diode 13. In an optional case, the width of the metal strip 16 can range from 0.05 mm to 0.15 mm. For example, the width of the metal strip 16 is 0.05 mm, 0.1 mm or 0.15 mm.

[0062] As an example, the tunable absorber 1 includes four frequency selection units 112. Figure 1 or Figure 2 As shown, the tunable absorber 1 includes four metal strips 16. Every two frequency selection units 112 are connected via one metal strip 16, so that the four frequency selection units 112 are connected in series to the external power supply.

[0063] In another example, the positive electrode of the microwave diode 13 is connected to the multiple frequency selection units 112. The negative electrode of the microwave diode 13 is connected to the central metal sheet 111. The multiple frequency selection units 112 connected in series through the multiple metal strips 16 are connected to the reverse voltage output terminal of the external power supply through the power supply terminal.

[0064] In another example, the cathode of the microwave diode 13 is connected to the plurality of frequency selection units 112. The anode of the microwave diode 13 is connected to the central metal sheet 111. The plurality of frequency selection units 112 connected in series through the plurality of metal thin strips 16 are connected to the forward voltage output terminal of the external power supply through the power supply terminal.

[0065] In the embodiment of the present application, the frequency selective surface layer 11 includes a central metal sheet 111 and a plurality of frequency selective units 112. The plurality of frequency selective units 112 are periodically arranged around the central metal sheet 111.

[0066] Alternatively, if Figure 5 As shown, in the frequency selective surface layer 11, the center point O1 of the central metal sheet 111 can be located at the center O0 of the frequency selective surface layer 11 and on the central axis L0 of the tunable absorber 1, so as to ensure the uniformity of the current distribution of the tunable absorber 1 in its height direction to a certain extent. For example, the central metal sheet 111 can be a central symmetrical pattern. Specifically, for example, the central metal sheet 111 can be a regular pattern metal sheet with central symmetrical characteristics, such as a diamond metal sheet, a square metal sheet, a regular hexagonal metal sheet, etc.

[0067] Further optionally, the central axis L1 of the conductive member 14 may also coincide with the central axis L0 of the tunable absorber 1 , so as to further ensure the uniformity of the current distribution of the tunable absorber 1 in the height direction thereof.

[0068] In an alternative case, if Figure 3 As shown, the conductive member 14 can pass through the dielectric substrate 12 and be respectively connected to the central metal sheet 111 and the metal grounding plate 15. For example, the dielectric substrate 12 has a via hole along the direction of the central axis L0 of the tunable absorber 1, and the conductive member 14 can pass through the via hole and be respectively welded to the central metal sheet 111 and the metal grounding plate 15.

[0069] The conductive member 14 may be an axisymmetric cylinder, and the area of ​​the cross section of the conductive member 14 is smaller than the area of ​​the central metal sheet 111. Optionally, the structure of the conductive member 14 may be a regular cylinder. For example, the conductive member 14 may be a cylinder, a cube, a cuboid, or a hexahedron. For example, when the conductive member 14 is a cylinder, the radius of the conductive member 14 may be in the range of 1.5 mm to 0.5 mm.

[0070] In some embodiments of the present application, each frequency selection unit 112 may be a metal sheet of the same shape, and the multiple frequency selection units 112 are arranged in a symmetrical structure, that is, the arrangement pattern of the multiple frequency selection units 112 on the frequency selection surface layer 11 is a symmetrical pattern.

[0071] Optionally, the number of frequency selection units 112 in the tunable absorber 1 may be an even number, so that the multiple frequency selection units 112 are arranged in a central symmetrical structure. Further optionally, the multiple frequency selection units 112 may be arranged around the central metal sheet 111 and along the circumference of the dielectric substrate 12 .

[0072] As an example, Figure 2 and Figure 4 As shown, the dielectric substrate 12 is a square. There are four frequency selection units 112. The four frequency selection units 112 are distributed at the four corners of the dielectric substrate 12 to form a symmetrical structure.

[0073] In another example, the dielectric substrate 12 is circular, and there are four frequency selection units 112. The four frequency selection units 112 are distributed at the four corners of the inner square of the dielectric substrate 12 to form a symmetrical structure.

[0074] In an alternative case, if Figure 2 As shown, a plurality of frequency selection units 112 are arranged in a central symmetrical structure. Each frequency selection unit 112 is a square metal sheet with the same shape. The hypotenuse of the missing corner of the square metal sheet 112 is connected to the central metal sheet 111 through a microwave diode 13. Optionally, the length of the side of the square metal sheet 112 that is not missing is in the range of 6 mm to 5 mm, the length of the side of the missing corner is in the range of 2.5 mm to 3.5 mm, and the missing corner triangle of the square metal sheet 112 is an isosceles right triangle. For example, the length of the side of the square metal sheet 112 that is not missing is in the range of 5.37 mm, the length of the side of the missing corner is in the range of 3 mm, and the missing corner triangle of the square metal sheet 112 is an isosceles right triangle, and the hypotenuse of the missing corner of the square metal sheet 112 is 3.21 mm.

[0075] In some embodiments of the present application, the frequency selective surface layer 11 as a whole can be an axisymmetric pattern. Based on this, the arrangement pattern of the multiple frequency selective units 112 on the frequency selective surface layer 11 is an axisymmetric pattern, and the pattern of the central metal sheet 111 is also an axisymmetric pattern. In addition, the arrangement pattern of the multiple frequency selective units 112 and the central metal sheet 111 have overlapping symmetry axes.

[0076] Alternatively, the frequency selective surface layer 11 as a whole may be a centrally symmetrical pattern. Based on this, the arrangement pattern of the plurality of frequency selective units 112 on the frequency selective surface layer 11 is a centrally symmetrical pattern, and the pattern of the central metal sheet 111 is also a centrally symmetrical pattern. Furthermore, the arrangement pattern of the plurality of frequency selective units 112 coincides with the center of the central metal sheet 111.

[0077] Further optionally, the microwave diode 13 is welded to the frequency selection unit 112 and the central metal sheet 111. The frequency selection surface layer 11 welded with the microwave diode 13 may be a central symmetrical pattern.

[0078] In an optional case, the dielectric substrate 12 is square, and the frequency selective surface layer 11 includes four frequency selective units 112. The central metal sheet 111 is a square metal sheet, and each frequency selective unit 112 is a square metal sheet.

[0079] Each frequency selection unit 112 is respectively arranged at the four corners of the dielectric substrate 12 , and two sides of the frequency selection unit 112 are respectively overlapped with two sides of the dielectric substrate 12 , and one corner of the frequency selection unit 112 is connected to one corner of the central metal sheet 111 through the microwave diode 13 .

[0080] In another alternative case, if Figure 2 and Figure 4 As shown, the dielectric substrate 12 is a square, and the frequency selective surface layer 11 includes four frequency selective units 112. The central metal sheet 111 is a regular hexagonal metal sheet, and each frequency selective unit 112 is a square metal sheet with the same shape and missing corners.

[0081] Among them, each frequency selection unit 112 is respectively arranged at the four corners of the dielectric substrate 12, and the two sides of the square metal sheet 112 without missing corners are respectively overlapped with the two sides of the dielectric substrate 12, and the hypotenuse of the missing corner of the square metal sheet 112 without missing corners is connected to the central metal sheet 111 through the microwave diode 13. Optionally, the side length of the central metal sheet 111 is equal to the side length of the missing corner of the frequency selection unit 112, and the side length of the central metal sheet 111 is less than the side length of the non-missing corner of the frequency selection unit 112. In this way, the tunable absorber provided in the embodiment of the present application has four absorbing frequency bands on the basis of adjustable absorbing frequency bands. Compared with the absorber of single frequency mode, dual-band mode, and broadband mode in the related art, the absorption frequency band width of the absorber for electromagnetic waves is effectively improved, and the adaptation scene is enriched.

[0082] In the embodiment of the present application, the frequency selective surface layer 11 and the metal ground plate 15 are respectively disposed on two opposite surfaces of the dielectric substrate 12. The frequency selective surface layer 11 and the metal ground plate 15 are both disposed in contact with the dielectric substrate 12.

[0083] Optionally, the size of the dielectric substrate 12 may be slightly larger than the size of the metal grounding plate 15 and the frequency selective surface layer 11, so as to completely isolate the metal grounding plate 15 and the frequency selective surface layer 11. For example, Figure 2 As shown, the metal ground plate 15 can be the same size as the dielectric substrate 12 .

[0084] In an optional case, the dielectric substrate 12 and the metal grounding plate 15 can both be regular shapes. In one example, the metal grounding plate 15 and the dielectric substrate 12 are both circular in shape. In another example, Figure 2 As shown, the metal grounding plate 15 and the dielectric substrate 12 are both square in shape. The length of the metal grounding plate 15 and the dielectric substrate 12 may range from 20 mm to 10 mm. For example, the length of the metal grounding plate 15 and the dielectric substrate 12 may range from 20 mm, 15 mm, or 10 mm. In addition, in some embodiments, the thickness of the dielectric substrate 12 may range from 1.5 mm to 2.5 mm. The thickness of the metal grounding plate 15 may range from 0.025 mm to 0.035 mm. For example, the thickness of the dielectric substrate 12 may range from 1.5 mm, 2 mm, or 2.5 mm. The thickness of the metal grounding plate 15 may range from 0.025 mm, 0.03 mm, or 0.035 mm.

[0085] In an embodiment of the present application, the tunable absorber includes: a frequency selective surface layer, a dielectric substrate, a microwave diode, a conductive member, and a metal ground plate. The frequency selective surface layer and the metal ground plate are respectively arranged on two opposite sides of the dielectric substrate. The frequency selective surface layer includes a central metal sheet, and a plurality of frequency selective units periodically arranged around the central metal sheet.

[0086] Among them, the microwave diode is respectively connected to the central metal sheet and multiple frequency selection units, and the central metal sheet is connected to the metal ground plate through a conductive member. In this way, the external power supply connected to the multiple frequency selection units and the metal ground plate can provide a reverse bias voltage to the microwave diode through the central metal sheet and the conductive member. And because the reverse bias voltage of the microwave diode can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, the adjustable absorber in the technical solution of the present application can achieve tuning of its absorbing frequency band by adjusting the size of the reverse bias voltage of the microwave diode, increase the absorbing frequency band of the absorber, and improve the absorbing efficiency to a certain extent.

[0087] In addition, the tunable absorber provided in the embodiment of the present application has four absorbing frequency bands based on the adjustable absorbing frequency band. Compared with the single-frequency mode absorber, the dual-band mode absorber, and the broadband mode absorber in the related art, the absorption frequency band width of the absorber for electromagnetic waves is effectively improved, enriching the adaptation scenarios.

[0088] In order to facilitate a better understanding of the tunable absorber provided in the embodiment of the present application, the tunable absorber involved in the technical solution of the present application is further explained with the following example.

[0089] For example, Figures 1 to 5 As shown, the tunable absorber includes: a frequency selective surface layer 11 , a dielectric substrate 12 , four microwave diodes 13 , a conductive member 14 , a metal ground plate 15 and metal thin strips 16 .

[0090] The frequency selective surface layer 11 and the metal grounding plate 15 are respectively attached to the two opposite surfaces of the dielectric substrate 12. The frequency selective surface layer 11 is a central symmetrical figure, which includes a central metal sheet 111 in the shape of a regular hexagon and four frequency selective units 112 in the shape of squares with missing corners. The metal grounding plate 15 and the dielectric substrate 12 are equal in size and are square in shape.

[0091] The regular hexagonal central metal sheet 111 is arranged in the exact center of the dielectric substrate 12, that is, the center point of the central metal sheet 111 coincides with the center point of the dielectric substrate 12. The four frequency selection units 112 are respectively arranged in the four corners of the dielectric substrate 12, and the two sides of the frequency selection unit 112 that are not missing are respectively arranged to overlap with the two sides of the dielectric substrate 12.

[0092] There is a gap between two adjacent frequency selection units 112 , and there is a thin gap between the missing corner hypotenuse of the frequency selection unit 112 and the central metal sheet 111 .

[0093] Two adjacent frequency selection units 112 are interconnected through a metal thin strip 16 attached to the dielectric substrate 12. Each microwave diode 13 is disposed in a thin slit of a corresponding frequency selection unit 112, and is respectively welded to the central metal sheet 111 and the frequency selection unit 112. In addition, the positive electrode of each microwave diode 13 is welded to the corresponding frequency selection unit 112, and the negative electrode of the microwave diode 13 is welded to the central metal sheet 111.

[0094] The conductive member 14 is in the shape of a cylinder. The center position of the dielectric substrate 12 has a through hole along the direction of the central axis of the tunable absorber 1, and the conductive member 14 can pass through the through hole and be welded to the central metal sheet 111 and the metal ground plate 15 respectively. In this way, the tunable absorber 1 of this example is an axisymmetric structure as a whole and has four absorbing frequency bands. Compared with the absorbers in the single frequency mode, the absorbers in the dual frequency band mode, and the absorbers in the broadband mode in the related art, the absorption frequency band width of the absorber for electromagnetic waves is effectively improved, and the adaptation scenes are enriched.

[0095] In the tunable absorber 1 of this example, the central metal sheet 111, the frequency selection unit 112, the conductive member 14, the metal ground plate 15 and the metal strip 16 are all made of copper. The material of the dielectric substrate 12 is FR4, which has a dielectric constant of 4.3 and a loss tangent of 0.025. FR4 is an insulating material, which has the characteristics of insulating performance, high high temperature resistance and high mechanical strength.

[0096] Furthermore, in the tunable absorber 1 of this example, the size of each component can be designed according to actual needs. Figure 6 As shown, in the frequency selective surface layer 11, the central metal sheet 111 in the shape of a regular hexagon may have a side length a of 4 mm. The frequency selective unit 112 in the shape of a square with missing corners may have a side length w1 of 5.37 mm, a side length w4 of 3 mm, and a hypotenuse length w3 of 3.21 mm. The width of the metal strip 16 may be 0.1 mm. The length and width L of the dielectric substrate 12 and the metal grounding plate 15 may be 15 mm. Furthermore, the thickness of the dielectric substrate 12 may be 2 mm. The thickness of the metal grounding plate 15 may be 0.03 mm. The microwave diode 13 may be a microwave diode of model SMV2019-079LF. The conductive member 14 in the shape of a cylinder may have a radius of 1 mm.

[0097] It should be noted that the material of the metal parts such as the central metal sheet 111, the frequency selection unit 112, the conductive member 14, the metal ground plate 15 and the metal strip 16 in the tunable absorber 1 is not limited to copper material, but may be other metal materials. Similarly, the material of the dielectric substrate 12 is not limited to FR4, but may be other insulating materials.

[0098] Furthermore, the multiple frequency selection units 112 and the metal ground plate 15 are used to be connected to an external power supply. The external power supply is used to provide a reverse bias voltage to the microwave diode 13. Since the reverse bias voltage of the microwave diode 13 can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode 13 can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, by adjusting the size of the reverse bias voltage of the microwave diode 13, the absorbing frequency band of the tunable absorber 1 can be tuned.

[0099] Please refer to Figure 7 , which shows the reflection coefficient S of the tunable absorber 1 to electromagnetic waves at various frequencies when different reverse bias voltages are provided to the tunable absorber 1 of this example. 11 Schematic diagram of the changes.

[0100] like Figure 7As shown, when a reverse bias voltage of 0V is applied to the microwave diode 13 of the tunable absorber 1, the reflection coefficient S of the tunable absorber 1 to the electromagnetic waves of four frequency bands is 11 Less than -10dB, these four frequency bands are absorbing frequency bands. The center frequency of each frequency band can be considered to be related to the reflection coefficient S 11 The frequency corresponding to the valley value of . Figure 7 It can be seen that when a reverse bias voltage of 0V is applied to the microwave diode 13 of the tunable absorber 1, the center frequency of the first absorbing frequency band is 8.8 GHz. The center frequency of the second absorbing frequency band is 12.15 GHz. The center frequency of the third absorbing frequency band is 16.11 GHz. The center frequency of the fourth absorbing frequency band is 18.2 GHz.

[0101] When a reverse bias voltage of -7V is applied to the microwave diode 13 of the tunable absorber 1, the tunable absorber 1 also has a reflection coefficient S of the electromagnetic waves of the four frequency bands. 11 Less than -10dB, these four frequency bands are the absorbing frequency bands. Figure 7 It can be seen that when a reverse bias voltage of -7V is applied to the microwave diode 13 of the tunable absorber 1, the center frequency of the first absorbing frequency band is 8.9 GHz. The center frequency of the second absorbing frequency band is 12.35 GHz. The center frequency of the third absorbing frequency band is 16.19 GHz. The center frequency of the fourth absorbing frequency band is 18.3 GHz.

[0102] When a reverse bias voltage of -14 V is applied to the microwave diode 13 of the tunable absorber 1, the tunable absorber 1 also has a reflection coefficient S of the electromagnetic waves of the four frequency bands. 11 Less than -10dB, these four frequency bands are the absorbing frequency bands. Figure 7 It can be seen that when a reverse bias voltage of -14V is applied to the microwave diode 13 of the tunable absorber 1, the center frequency of the first absorbing frequency band is 9.0GHz. The center frequency of the second absorbing frequency band is 12.55GHz. The center frequency of the third absorbing frequency band is 16.24GHz. The center frequency of the fourth absorbing frequency band is 18.4GHz.

[0103] When a reverse bias voltage of -19 V is applied to the microwave diode 13 of the tunable absorber 1, the tunable absorber 1 also has a reflection coefficient S of the electromagnetic waves of the four frequency bands. 11 Less than -10dB, these four frequency bands are the absorbing frequency bands. Figure 7It can be seen that when a reverse bias voltage of -19V is applied to the microwave diode 13 of the tunable absorber 1, the center frequency of the first absorbing frequency band is 9.14 GHz. The center frequency of the second absorbing frequency band is 12.67 GHz. The center frequency of the third absorbing frequency band is 16.3 GHz. The center frequency of the fourth absorbing frequency band is 18.5 GHz.

[0104] Based on this, it can be seen that when reverse bias voltages of 0V, -7, -14V, and -19V are applied to the microwave diode 13 of the tunable absorber 1, the four absorbing frequency bands of the tunable absorber 1 are offset. Among them, the tuning range (offset range) of the first absorbing frequency band is at least 8.8-9.14GHz, the tuning range of the second absorbing frequency band is at least 12.15-12.67GHz, and the tuning range of the third absorbing frequency band is at least 16.11-16.3GHz. The tuning range of the fourth absorbing frequency band is at least 18.2-18.5GHz.

[0105] Correspondingly, as different reverse bias voltages are applied to the microwave diode 13 of the tunable absorber 1, the absorption rate of the tunable absorber 1 to electromagnetic waves of different frequencies will also change. This change can also intuitively reflect that the absorption frequency band is adjusted under the influence of the reverse bias voltage of the microwave diode 13.

[0106] Please refer to Figure 8 , which shows a schematic diagram of changes in the absorption rate of the tunable absorber 1 to electromagnetic waves at various frequencies when different reverse bias voltages are provided to the tunable absorber 1 of this example.

[0107] like Figure 8 As shown, when a 0V reverse bias voltage is applied to the microwave diode 13 of the tunable absorber 1, the tunable absorber 1 has a high absorption rate for electromagnetic waves in four frequency bands, and the four frequency bands are the absorption frequency bands. Figure 8 It can be seen that when a reverse bias voltage of 0V is applied to the microwave diode 13 of the tunable absorber 1, the peak absorption rate of the first absorption frequency band is 97.8%, the peak absorption rate of the second absorption frequency band is 89.7%, the peak absorption rate of the third absorption frequency band is 92%, and the peak absorption rate of the fourth absorption frequency band is 98.8%.

[0108] When a reverse bias voltage of -7V is applied to the microwave diode 13 of the tunable absorber 1, the tunable absorber 1 also has a high absorption rate for electromagnetic waves in four frequency bands, and the four frequency bands are the absorption frequency bands. Figure 8It can be seen that when a reverse bias voltage of -7V is applied to the microwave diode 13 of the tunable absorber 1, the peak absorption rate of the first absorption frequency band is 83%, the peak absorption rate of the second absorption frequency band is 91%, the peak absorption rate of the third absorption frequency band is 93%, and the peak absorption rate of the fourth absorption frequency band is 99.1%.

[0109] When a reverse bias voltage of -14V is applied to the microwave diode 13 of the tunable absorber 1, the tunable absorber 1 also has a high absorption rate for electromagnetic waves in four frequency bands, and the four frequency bands are the absorption frequency bands. Figure 8 It can be seen that when a reverse bias voltage of -14 V is applied to the microwave diode 13 of the tunable absorber 1, the peak absorption rate of the first absorbing frequency band is 72%, the peak absorption rate of the second absorbing frequency band is 92%, the peak absorption rate of the third absorbing frequency band is 94%, and the peak absorption rate of the fourth absorbing frequency band is 99.3%.

[0110] When a reverse bias voltage of -19V is applied to the microwave diode 13 of the tunable absorber 1, the tunable absorber 1 also has a high absorption rate for electromagnetic waves in four frequency bands, and the four frequency bands are the absorption frequency bands. Figure 8 It can be seen that when a reverse bias voltage of -19 V is applied to the microwave diode 13 of the tunable absorber 1, the peak absorption rate of the first absorption frequency band is 58%, the peak absorption rate of the second absorption frequency band is 93.4%, the peak absorption rate of the third absorption frequency band is 95%, and the peak absorption rate of the fourth absorption frequency band is 99.9%.

[0111] Based on this, it can be seen that when reverse bias voltages of 0V, -7, -14V, and -19V are applied to the microwave diode 13 of the tunable absorber 1, the peak values ​​of the absorbance of the four absorbing frequency bands of the tunable absorber 1 also shift, which also reflects that the four absorbing frequency bands have a shift phenomenon. Among them, the tuning range (shift range) of the peak value of the absorbance of the first absorbing frequency band is 97.8%-58%, the tuning range of the peak value of the absorbance of the second absorbing frequency band is 89.7%-93.4%, the tuning range of the peak value of the absorbance of the third absorbing frequency band is 92%-95%, and the tuning range of the peak value of the absorbance of the fourth absorbing frequency band is 98.8%-99.9%.

[0112] Obviously, the adjustable absorber provided in the embodiment of the present application can tune the absorbing frequency band of the microwave diode by adjusting the magnitude of the reverse bias voltage thereof, thereby increasing the absorbing frequency band of the absorber and improving the absorbing efficiency to a certain extent.

[0113] In addition, the adjustable absorber provided in the embodiment of the present application also has multiple characteristics. For example, the adjustable absorber has a simple structure, a thin thickness, and is easy to process and install. In addition, the adjustable absorber is easy to apply to various integrated systems due to its small surface area and simple structure, thus enriching the application scenarios.

[0114] In an embodiment of the present application, the tunable absorber includes: a frequency selective surface layer, a dielectric substrate, a microwave diode, a conductive member, and a metal ground plate. The frequency selective surface layer and the metal ground plate are respectively arranged on two opposite sides of the dielectric substrate. The frequency selective surface layer includes a central metal sheet, and a plurality of frequency selective units periodically arranged around the central metal sheet.

[0115] Among them, the microwave diode is respectively connected to the central metal sheet and multiple frequency selection units, and the central metal sheet is connected to the metal ground plate through a conductive member. In this way, the external power supply connected to the multiple frequency selection units and the metal ground plate can provide a reverse bias voltage to the microwave diode through the central metal sheet and the conductive member. And because the reverse bias voltage of the microwave diode can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, the adjustable absorber in the technical solution of the present application can achieve tuning of its absorbing frequency band by adjusting the size of the reverse bias voltage of the microwave diode, increase the absorbing frequency band of the absorber, and improve the absorbing efficiency to a certain extent.

[0116] The present application also provides an electronic device. The electronic device includes the tunable absorber provided in the present application. Optionally, the electronic device includes Figure 1 , Figure 2 , Figure 4 or Figure 5 The tunable absorber shown in the figure comprises: a frequency selective surface layer, a dielectric substrate, a microwave diode, a conductive member and a metal grounding plate. The frequency selective surface layer and the metal grounding plate are respectively arranged on two opposite sides of the dielectric substrate. The frequency selective surface layer comprises a central metal sheet and a plurality of frequency selective units periodically arranged around the central metal sheet.

[0117] Among them, the microwave diode is respectively connected to the central metal sheet and multiple frequency selection units, and the central metal sheet is connected to the metal ground plate through a conductive member. In this way, the external power supply connected to the multiple frequency selection units and the metal ground plate can provide a reverse bias voltage to the microwave diode through the central metal sheet and the conductive member. And because the reverse bias voltage of the microwave diode can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, the adjustable absorber in the technical solution of the present application can achieve tuning of its absorbing frequency band by adjusting the size of the reverse bias voltage of the microwave diode, increase the absorbing frequency band of the absorber, and improve the absorbing efficiency to a certain extent.

[0118] Optionally, the embodiment of the present application further provides an antenna system. The antenna system includes the tunable absorber provided in the embodiment of the present application. Optionally, the electronic device includes Figure 1 , Figure 2 , Figure 4 or Figure 5 The tunable absorber shown in the figure comprises: a frequency selective surface layer, a dielectric substrate, a microwave diode, a conductive member and a metal grounding plate. The frequency selective surface layer and the metal grounding plate are respectively arranged on two opposite sides of the dielectric substrate. The frequency selective surface layer comprises a central metal sheet and a plurality of frequency selective units periodically arranged around the central metal sheet.

[0119] Among them, the microwave diode is respectively connected to the central metal sheet and multiple frequency selection units, and the central metal sheet is connected to the metal ground plate through a conductive member. In this way, the external power supply connected to the multiple frequency selection units and the metal ground plate can provide a reverse bias voltage to the microwave diode through the central metal sheet and the conductive member. And because the reverse bias voltage of the microwave diode can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, the adjustable absorber in the technical solution of the present application can achieve tuning of its absorbing frequency band by adjusting the size of the reverse bias voltage of the microwave diode, increase the absorbing frequency band of the absorber, and improve the absorbing efficiency to a certain extent.

[0120] Optionally, the embodiment of the present application further provides a radar system. The radar system includes the tunable absorber provided in the embodiment of the present application. Optionally, the electronic device includes Figure 1 , Figure 2 , Figure 4 or Figure 5The tunable absorber shown in the figure comprises: a frequency selective surface layer, a dielectric substrate, a microwave diode, a conductive member and a metal grounding plate. The frequency selective surface layer and the metal grounding plate are respectively arranged on two opposite sides of the dielectric substrate. The frequency selective surface layer comprises a central metal sheet and a plurality of frequency selective units periodically arranged around the central metal sheet.

[0121] Among them, the microwave diode is respectively connected to the central metal sheet and multiple frequency selection units, and the central metal sheet is connected to the metal ground plate through a conductive member. In this way, the external power supply connected to the multiple frequency selection units and the metal ground plate can provide a reverse bias voltage to the microwave diode through the central metal sheet and the conductive member. And because the reverse bias voltage of the microwave diode can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, the adjustable absorber in the technical solution of the present application can achieve tuning of its absorbing frequency band by adjusting the size of the reverse bias voltage of the microwave diode, increase the absorbing frequency band of the absorber, and improve the absorbing efficiency to a certain extent.

[0122] Optionally, the embodiment of the present application further provides a wireless communication system. The wireless communication system includes the tunable absorber provided in the embodiment of the present application. Optionally, the electronic device includes Figure 1 , Figure 2 , Figure 4 or Figure 5 The tunable absorber shown in the figure comprises: a frequency selective surface layer, a dielectric substrate, a microwave diode, a conductive member and a metal grounding plate. The frequency selective surface layer and the metal grounding plate are respectively arranged on two opposite sides of the dielectric substrate. The frequency selective surface layer comprises a central metal sheet and a plurality of frequency selective units periodically arranged around the central metal sheet.

[0123] Among them, the microwave diode is respectively connected to the central metal sheet and multiple frequency selection units, and the central metal sheet is connected to the metal ground plate through a conductive member. In this way, the external power supply connected to the multiple frequency selection units and the metal ground plate can provide a reverse bias voltage to the microwave diode through the central metal sheet and the conductive member. And because the reverse bias voltage of the microwave diode can adjust the size of its equivalent capacitance, and the size of the equivalent capacitance of the microwave diode can affect the size of the surface current of the absorber, thereby affecting the absorption frequency that changes with the surface current. Therefore, the adjustable absorber in the technical solution of the present application can achieve tuning of its absorbing frequency band by adjusting the size of the reverse bias voltage of the microwave diode, increase the absorbing frequency band of the absorber, and improve the absorbing efficiency to a certain extent.

[0124] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0125] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0126] The above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A tunable absorber, characterized in that: The tunable absorber comprises: Frequency selective surface layer, dielectric substrate, microwave diode, conductive member and metal ground plate; The frequency selective surface layer and the metal ground plate are respectively arranged on two opposite surfaces of the dielectric substrate; The frequency selective surface layer comprises a central metal sheet and a plurality of frequency selective units, wherein the plurality of frequency selective units are periodically arranged around the central metal sheet; The microwave diode is connected to the central metal sheet and the multiple frequency selection units respectively, the central metal sheet is connected to the metal ground plate through the conductive member, the multiple frequency selection units and the metal ground plate are both used to be connected to an external power supply, and the external power supply is used to provide a reverse bias voltage to the microwave diode.

2. The tunable absorber according to claim 1, characterized in that: The number of the microwave diodes is multiple and corresponds one-to-one to the frequency selection units; Each of the microwave diodes is connected to the central metal sheet and to the corresponding frequency selection unit.

3. The tunable absorber according to claim 2, characterized in that: There is a fine gap between each of the frequency selection units and the central metal sheet, and each of the microwave diodes is arranged in the fine gap and is respectively connected to the central metal sheet and the corresponding frequency selection unit.

4. The tunable absorber according to any one of claims 1 to 3, characterized in that: The tunable absorber further comprises: a plurality of metal thin strips; Each of the metal strips is connected to two adjacent frequency selection units to connect the multiple frequency selection units with a power supply terminal, and the power supply terminal is used to connect the external power supply.

5. The tunable absorber according to any one of claims 1 to 3, characterized in that: The center point of the central metal sheet is located at the center of the frequency selective surface layer and on the central axis of the tunable absorber.

6. The tunable absorber according to claim 5, characterized in that: The central axis of the conductive member coincides with the central axis of the tunable absorber.

7. The tunable absorber according to any one of claims 1 to 3, characterized in that: Each of the frequency selection units is a metal sheet with the same shape, and the multiple frequency selection units are arranged in a symmetrical structure.

8. The tunable absorber according to claim 6, characterized in that: The frequency selective surface layer is a centrally symmetrical pattern.

9. The tunable absorber according to claim 7, characterized in that: The dielectric substrate is square, and the frequency selective surface layer includes four frequency selective units; The central metal sheet is a regular hexagonal metal sheet, each of the frequency selection units is a square metal sheet with a same shape, each of the frequency selection units is respectively arranged at the four corners of the dielectric substrate, and the two non-missing sides of the square metal sheet with a missing corner are respectively overlapped with the two sides of the dielectric substrate, and the missing side of the square metal sheet with a missing corner is connected to the central metal sheet through the microwave diode.

10. The tunable absorber according to claim 9, characterized in that: The side length of the central metal sheet is equal to the side length of the frequency selection unit with a missing corner, and is smaller than the side length of the frequency selection unit without a missing corner.

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