A non-reciprocal metasurface device and control method

Abstract

The present invention discloses a non-reciprocal metasurface device, comprising a metasurface unit; each of the metasurface units is composed of a three-layer structure of a radiation patch, a dielectric substrate and a metal backplane, wherein the radiation patch is on the top surface of the dielectric substrate and the metal backplane is on the bottom surface of the dielectric substrate; the metasurface unit is used to load different unit phase values ​​according to the phase value of a time-varying modulation signal during forward frequency conversion and backward frequency conversion, so as to realize the non-reciprocity of beam pointing. The present invention also discloses a non-reciprocal metasurface control method using the device. The present invention realizes a highly integrated non-reciprocal device, especially using point-to-point communication.

Description

Technical Field

[0001] The present invention relates to the field of metasurface technology, and in particular to a non-reciprocal metasurface device and a control method. Background Art

[0002] Metasurface is a two-dimensional artificial electromagnetic metamaterial, which is composed of periodic or non-periodic arrangement of sub-wavelength units. Metasurface has extraordinary physical properties and can achieve novel electromagnetic properties that natural materials in nature cannot achieve. Metasurface can regulate the transmission of electromagnetic waves by utilizing the phase mutation characteristics generated on the unit surface. Traditional electromagnetic non-reciprocal devices often rely on magnetic materials such as ferrites to break the time reversal symmetry and achieve non-reciprocal transmission of electromagnetic waves. For example, isolators are a common non-reciprocal device. The loss value is greatly different when transmitting in the forward and reverse directions, and the signal can only be transmitted in a directional manner. However, magnetic materials are not compatible with integrated circuit processing technology, and there is a problem of difficulty in integration. Summary of the invention

[0003] The present invention provides a non-reciprocal metasurface device and a control method to solve the problem that the device and the method are difficult to integrate.

[0004] To solve the above problems, the present invention is achieved as follows:

[0005] An embodiment of the invention provides a non-reciprocal metasurface device, comprising a metasurface unit; each of the metasurface units is composed of a three-layer structure of a radiation patch, a dielectric substrate and a metal backplane, the radiation patch is on the top surface of the dielectric substrate, and the metal backplane is on the bottom surface of the dielectric substrate; the metasurface unit is used to load different unit phase values ​​according to the phase value of a time-varying modulation signal during forward frequency conversion and backward frequency conversion, so as to achieve non-reciprocity of beam pointing.

[0006] The forward frequency conversion is a conversion of a first frequency into a second frequency, the backward frequency conversion is a conversion of a second frequency into a first frequency, the time-varying modulation signal is a sinusoidal signal, and the frequency of the time-varying modulation signal is a frequency difference between the first frequency and the second frequency.

[0007] Furthermore, the metal backplane contains a feeding circuit, which includes: a one-to-two power division network, first and second metallized through holes, a time-varying modulation signal feeding port, first and second inductors, first and second capacitors, and first and second varactor diodes; the first and second metallized through holes are used to connect the two ends of the one-to-two power division network to the edge of the radiation patch; the time-varying modulation signal feeding port is located at the input end of the one-to-two power division network, and the time-varying modulation signal enters the one-to-two power division network through the time-varying modulation signal feeding port.

[0008] When performing forward frequency conversion, the first incident signal passes through the first metallized through hole and the first inductor to the first varactor diode, is mixed with the time-varying modulation signal, and then the low-frequency signal is isolated through the first capacitor, and then passes through the second capacitor, the second varactor diode and the second inductor to the second metallized through hole to output the first output signal.

[0009] When performing backward frequency conversion, the second incident signal passes through the second metallized through hole and the second capacitor to the second varactor diode, is mixed with the time-varying modulation signal, and then the high-frequency signal is isolated by the second inductor, and then passes through the first capacitor, the first varactor diode, and the first inductor to the first metallized through hole to output the second output signal.

[0010] The frequencies of the first incident signal and the second output signal are both the first frequency, and the frequencies of the first output signal and the second incident signal are both the second frequency.

[0011] Furthermore, the non-reciprocal metasurface device is formed by uniformly arranging the metasurface units in a rectangular arrangement.

[0012] Furthermore, the size and number of the metasurface units are determined by the metasurface operating frequency and a preset directional angle of a first output signal, where the first output signal is an output signal during forward frequency conversion.

[0013] Preferably, the metasurface unit adopts a square copper radiation patch and a copper metal backplane.

[0014] Preferably, the frequency of the time-varying modulation signal is 40 MHz, the operating frequency of the metasurface is 2.5 GHz, and the dielectric substrate uses Rogers 5880 material with a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 1.575 mm.

[0015] Preferably, the unit phase value of the metasurface unit is determined by the following formula 1.

[0016] Preferably, the side length of the square copper radiation patch is 45 mm.

[0017] An embodiment of the present invention also provides a non-reciprocal metasurface control method, using the device described in any embodiment of the present invention, comprising the following steps: calculating the size and number of metasurface units based on a known metasurface operating frequency and a beam width of a first output signal, wherein the first output signal is an output signal when performing forward frequency conversion; calculating the unit phase value of each metasurface unit based on a first incident pitch angle of a first incident signal and a first output pitch angle of the first output signal, wherein the first incident signal is an incident signal when performing forward frequency conversion; determining the time-varying modulation signal phase based on the relationship between the time-varying modulation signal phase and the unit phase value during forward frequency conversion.

[0018] The beneficial effects of the present invention include: First, the present invention does not rely on magnetic materials such as ferrites, and adopts the method of time-varying modulation signals to realize an integrable non-reciprocal metasurface, which has the advantage of being integrable. Second, after the introduction of non-reciprocity, the novel functions of the non-reciprocal metasurface are further enriched, and the invented non-reciprocal metasurface is a multifunctional device. Third, the present invention can regulate the spatial phase distribution of the electromagnetic wave reflected by the metasurface only by controlling the phase of the low-frequency time-varying modulation signal, thereby realizing non-reciprocal spatial domain beam pointing, which has the effect of being flexible and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] FIG. 1( a ) is a schematic diagram of a metasurface device of an embodiment of a non-reciprocal metasurface device;

[0021] FIG1( b ) is a schematic diagram of a metasurface unit of an embodiment of a non-reciprocal metasurface device;

[0022] FIG1( c ) is a front view schematic diagram of a feeding circuit of an embodiment of a non-reciprocal metasurface device;

[0023] FIG1( d ) is a schematic diagram of the back side of a feeding circuit of an embodiment of a non-reciprocal metasurface device;

[0024] Figure 2 An embodiment of a curve showing a relationship between a unit phase value of a metasurface unit and a phase of a time-varying modulation signal;

[0025] Figure 3 It is an embodiment of a non-reciprocal metasurface device structure;

[0026] Figure 4 An embodiment of non-reciprocal pointing of a spatial beam;

[0027] FIG5( a ) is a forward frequency conversion distribution diagram of a metasurface unit phase distribution and a spatial beam pointing embodiment;

[0028] FIG5( b ) is a backward frequency conversion distribution diagram of a metasurface unit phase distribution and a spatial beam pointing embodiment;

[0029] Figure 6 The present invention is an implementation example of a non-reciprocal metasurface control method process. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] Electromagnetic nonreciprocity refers to the different losses or phase shifts when electromagnetic waves are transmitted in two opposite directions. In recent years, the method of using time-varying modulation signals has been proven to break the time reversal symmetry to achieve nonreciprocity. It does not rely on magnetic materials and has the advantage of being integrated. Therefore, the method based on time-varying modulation signals to achieve an integrated nonreciprocal metasurface will further enhance and enrich the functions of the metasurface, broaden the application scope of the metasurface, and has broad application prospects.

[0032] The innovation of the present invention lies in: different from existing magnetic materials such as ferrite, the present invention realizes the non-reciprocity of spatial beam pointing through the design of metasurface materials, and has the advantage of high integration; in addition, the present invention can adjust the beam pointing of the outgoing signal by changing the phase value of the time-varying modulation signal by design, and the beam pointing has higher flexibility.

[0033] The technical solutions provided by various embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0034] Figure 1(a) is a schematic diagram of a metasurface device of an embodiment of a non-reciprocal metasurface device, Figure 1(b) is a schematic diagram of a metasurface unit of an embodiment of a non-reciprocal metasurface device, Figure 1(c) is a front schematic diagram of a feeding circuit of an embodiment of a non-reciprocal metasurface device, and Figure 1(d) is a back schematic diagram of a feeding circuit of an embodiment of a non-reciprocal metasurface device.

[0035] In an embodiment of the present invention, a non-reciprocal metasurface device 1 comprises: a plurality of identical metasurface units 2, each of which is composed of a three-layer structure of a radiation patch 11, a dielectric substrate 12 and a metal backplane 13, wherein the metal backplane comprises a feeding circuit 14.

[0036] In an embodiment of the present invention, the radiation patch is on the top surface of the dielectric substrate, and the metal backplane is on the bottom surface of the dielectric substrate; the metasurface unit is used to load different unit phase values ​​according to the phase value of the time-varying modulation signal during forward frequency conversion and backward frequency conversion, so as to achieve non-reciprocity of beam pointing.

[0037] It should be noted that the forward frequency conversion is the conversion of the first frequency into the second frequency, the backward frequency conversion is the conversion of the second frequency into the first frequency, the time-varying modulation signal is a sinusoidal signal, and the frequency of the time-varying modulation signal is the frequency difference between the first frequency and the second frequency.

[0038] In an embodiment of the present invention, the non-reciprocal metasurface device is used to realize forward and backward beam reflection. Forward beam reflection refers to that a first incident signal irradiates the device at a first incident pitch angle, and after reflection, a first outgoing signal with an outgoing angle of the first outgoing pitch angle is formed. Backward beam reflection refers to that a second incident signal irradiates the device at a second incident pitch angle, and after reflection, a second outgoing signal with an outgoing angle of the second outgoing pitch angle is formed.

[0039] It should be noted that, in the present invention, the first incident pitch angle is the angle between the beam center of the first incident signal and the normal of the non-reciprocal metasurface device, the first output pitch angle is the angle between the beam center of the first output signal and the normal of the non-reciprocal metasurface device, and the first output horizontal angle is the angle between the projection of the beam center of the first output signal on the device surface and one of the coordinate axes. The non-reciprocal metasurface device normal (device normal) is a straight line perpendicular to the device surface and passing through the center of the device surface.

[0040] Correspondingly, the second incident pitch angle is the angle between the beam center of the second incident signal and the device normal, and the second exit pitch angle is the angle between the beam center of the second exit signal and the device normal.

[0041] It should be noted that the embodiment of the present invention realizes non-reciprocity of beam pointing, which means that when the first exit elevation angle and the second incident elevation angle are the same, the first incident elevation angle and the second exit elevation angle are different.

[0042] It should also be noted that the frequencies of the first incident signal and the second outgoing signal are the same, both are the first frequency, and the frequencies of the first outgoing signal and the second incident signal are the same, both are the second frequency.

[0043] In an embodiment of the present invention, there is a linear correspondence between the unit phase value of the metasurface unit and the phase value of the time-varying modulation signal. The correspondence between the unit phase value and the phase value of the time-varying modulation signal is different during forward frequency conversion and backward frequency conversion. Therefore, the non-reciprocity of beam pointing can be achieved during forward frequency conversion and backward frequency conversion.

[0044] In an embodiment of the present invention, the non-reciprocal metasurface device may be composed of a periodic arrangement of identical metasurface units, for example, arranged in a rectangular structure, or arranged in a circular arrangement; the non-reciprocal metasurface device may also be arranged in other arrangements, such as a sparse array arrangement, which is not particularly limited here.

[0045] FIG1( a ) provides a non-reciprocal metasurface device in a rectangular arrangement, comprising 6×6 (rows×columns) metasurface units. The embodiment of the present invention does not limit the number of metasurface units.

[0046] In an embodiment of the present invention, the metasurface unit may be a square copper radiating patch, or may be a radiating patch of other shapes or materials, such as a circular radiating patch, without particular limitation. The metal back plate may be a copper metal back plate, or other metal materials, without particular limitation. The metasurface unit may be realized by conventional PCB processing technology.

[0047] In an embodiment of the present invention, the second frequency may be greater than the first frequency, that is, frequency conversion for up-conversion is achieved during forward frequency conversion; the second frequency may also be less than the first frequency, that is, frequency conversion for down-conversion is achieved during forward frequency conversion.

[0048] Figure 1(c) provides an embodiment of a feeding circuit in which the second frequency is greater than the first frequency, which can be used to perform frequency conversion and feeding of a metasurface unit. The feeding circuit 14 includes: a one-to-two power division network 401, a first metallized through hole 403, a second metallized through hole 402, a time-varying modulation signal feeding port 404, a first inductor 409, a second inductor 406, a first capacitor 408, a second capacitor 405, a first varactor diode 410, and a second varactor diode 407.

[0049] The first and second metallized through holes are used to connect the two ends of the one-to-two power division network to the edge of the radiation patch; the time-varying modulation signal feeding port is located at the input end of the one-to-two power division network, and the time-varying modulation signal enters the one-to-two power division network through the time-varying modulation signal feeding port.

[0050] When performing forward frequency conversion, the first incident signal passes through the first metallized through hole and the first inductor to the first varactor diode, is mixed with the time-varying modulation signal, and then the low-frequency signal is isolated through the first capacitor, and then passes through the second capacitor, the second varactor diode and the second inductor to the second metallized through hole to output the first output signal.

[0051] When performing backward frequency conversion, the second incident signal passes through the second metallized through hole and the second capacitor to the second varactor diode, is mixed with the time-varying modulation signal, and then the high-frequency signal is isolated by the second inductor, and then passes through the first capacitor, the first varactor diode, and the first inductor to the first metallized through hole to output the second output signal.

[0052] In an embodiment of the present invention, the first capacitor and the second capacitor are used to isolate low-frequency signals generated during frequency mixing, the first inductor and the second inductor are used to isolate high-frequency signals generated during frequency mixing, and the varactor diode acts as a variable capacitor when used for frequency mixing and working in a reverse bias state.

[0053] In the embodiment of the present invention, the one-to-two power division network is a T-shaped one-to-two power division network. It should be noted that the one-to-two power division network can also be other shapes of one-to-two power division networks, which is not particularly limited here.

[0054] Specifically, for example, the metasurface operating frequency is designed to be 2.5 GHz, the high-frequency end center frequency is designed to be 1.8 GHz, and the time-varying modulation signal is a low-frequency signal with a frequency of f m =40MHz.

[0055] When performing forward frequency conversion, the operating frequency of the first incident signal is the first frequency f0, and the operating frequency of the first output signal is the second frequency f0+f m The time-varying modulation signal enters the one-to-two power division network through the time-varying modulation signal feed port, one path passes through the first capacitor to the first varactor diode, and the other path passes through the second capacitor to the second varactor diode. The first incident signal passes through the first metallized through hole and the first inductor to the first varactor diode. The varactor diode mixes the time-varying modulation signal and the first incident signal to generate a frequency of f0±f m Two signals, where the frequency is f0+f m The signal passes through the first capacitor, the second capacitor, and the second inductor to form a first output signal with a frequency of f0-f m The signal is filtered out at the first capacitor.

[0056] When performing backward frequency conversion, the operating frequency of the second incident signal is the second frequency f0+f m, the operating frequency of the second output signal is the first frequency f0. The time-varying modulation signal enters the one-to-two power division network through the time-varying modulation signal feed port, one path passes through the second capacitor to the second varactor diode, and the other path passes through the first capacitor to the first varactor diode. The second incident signal passes through the second metallized through hole and the second inductor to the second varactor diode. The varactor diode mixes the time-varying modulation signal and the second incident signal to generate frequencies of f0 and f0+2f m The signal with a frequency of f0 is formed into a second output signal after passing through the second capacitor, the first capacitor and the first inductor, and the frequency is f0+2f m The signal is filtered out at the second capacitor.

[0057] In the embodiment of the present invention, the high frequency end center frequency is designed to be 1.8 GHz, which means that signals with frequencies greater than 1.8 GHz will be filtered out.

[0058] It should be noted that FIG. 1(c) provides a feeding circuit with a second frequency greater than the first frequency. The feeding circuit with a second frequency less than the first frequency is similar to the feeding circuit with a second frequency greater than the first frequency. The corresponding filter circuit can be designed to obtain frequencies f0 and f0-f m Signal.

[0059] FIG1( d ) is a schematic diagram of the back side of a portion of the feeding circuit, including a first inductor, a first varactor diode and a first capacitor. The first inductor, the first varactor diode and the first capacitor are electrically connected on the back side of the metal back plate using PCB technology.

[0060] It should be noted that the connection method of the second inductor, the second capacitor and the second varactor diode is similar to that of FIG. 1( d ), and the entire feeding circuit is axially symmetrical with respect to the time-varying modulation signal feeding port.

[0061] The embodiment of the present invention relates to a non-reciprocal metasurface based on a time-varying modulated signal, which does not rely on magnetic materials to break the time reversal symmetry to achieve non-reciprocal transmission of electromagnetic waves, and is compatible with integrated circuit processing technology. The invented non-reciprocal metasurface device achieves non-reciprocity of spatial domain beam pointing during forward frequency conversion and backward frequency conversion by adjusting the phase of the modulated signal in each unit, and can be applied to in-band full-duplex communication, point-to-point communication and other fields.

[0062] Figure 2 This is an embodiment of a curve showing the relationship between the unit phase value of a metasurface unit and the phase of a time-varying modulation signal.

[0063] exist Figure 2In the figure, the horizontal axis represents the phase value of the time-varying modulation signal, in degrees, and the vertical axis represents the unit phase value of a certain metasurface unit, in degrees; the solid line is the relationship between the phase value of the time-varying modulation signal and the unit phase value of the metasurface unit during forward frequency conversion, and the dotted line is the relationship between the phase value of the time-varying modulation signal and the unit phase value of the metasurface unit during backward frequency conversion.

[0064] In an embodiment of the present invention, the metasurface units of the non-reciprocal metasurface device are arranged in a rectangular form, and the metasurface units use square copper radiation patches, and the side length of the radiation patch is half the medium wavelength at the central operating frequency of the metasurface.

[0065] In an embodiment of the present invention, the dielectric substrate of the non-reciprocal metasurface uses Rogers 5880 material, with a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 1.575 mm. The central operating frequency of the metasurface is designed to be 2.5 GHz, the central frequency of the high-frequency end is designed to be 1.8 GHz, and the side length of the square copper radiation patch is 45 mm. The varactor diode in the time-varying modulation circuit adopts the Skyworks SMV1233 model, the inductor adopts a 20nH chip inductor, and the capacitor adopts a 5pF chip capacitor. The number of metasurface units is 12×12, and the unit spacing is 75 mm.

[0066] from Figure 2 It can be seen that during the forward frequency conversion and the backward frequency conversion, the unit phase value of the metasurface unit is linearly related to the phase value of the time-varying modulation signal. The slope of the unit phase value and the phase value of the time-varying modulation signal during the forward frequency conversion process and the slope of the unit phase value and the phase value of the time-varying modulation signal during the backward frequency conversion process are equal in magnitude and opposite in sign.

[0067] Figure 2 The phase relationship between the unit phase value and the time-varying modulation signal phase value during the forward frequency conversion and the backward frequency conversion is determined according to the physical characteristics of the varactor diode.

[0068] from Figure 2 It can be seen that the time-varying modulation signal phase value can be determined by determining the unit phase value of the metasurface unit. Correspondingly, the unit phase value of the metasurface unit can be changed by adjusting the time-varying modulation signal phase value, thereby changing the first output pitch angle of the first output signal.

[0069] In the embodiment of the present invention, when forward frequency conversion is performed, the time-varying modulation signal phase value can be determined by the first incident pitch angle and the first exit pitch angle; when backward frequency conversion is performed, the second incident pitch angle is the same as the first exit pitch angle. Figure 2 From the relationship curve, it is obvious that the second exit elevation angle is not equal to the first incident elevation angle, thus realizing the spatial beam non-reciprocity.

[0070] It should be noted that Figure 2 A relationship curve between the unit phase value of a certain metasurface unit and the phase value of the time-varying modulation signal is provided, and the relationship between the phase value of the spatial beam (the first outgoing signal and the second outgoing signal) synthesized by all metasurface units and the phase value of the time-varying modulation signal is also linear.

[0071] Figure 3 This is an embodiment of a non-reciprocal metasurface device structure, which can be used to calculate the unit phase value of the metasurface unit.

[0072] like Figure 3 As shown, the metasurface units are evenly arranged in a square arrangement to form a metasurface device, the unit spacing of the metasurface units is d, the first incident pitch angle is θ1, and the first exit pitch angle is θ2.

[0073] The unit phase value of the metasurface unit is:

[0074]

[0075] k1=2πf0 / c (2)

[0076] k2=2π(f0+f m ) / c (3)

[0077] Wherein, i and j are the row number and column number of the metasurface unit, respectively; k1 and k2 are the wave numbers of the signal with the first and second frequencies, respectively; θ1 and θ2 are the first incident pitch angle of the first incident signal and the first exit pitch angle of the first exit signal, respectively; is the first output horizontal angle of the first output signal, c is the speed of light, and d is the unit spacing between the metasurface units.

[0078] In an embodiment of the present invention, is the expression of the beam center pointing in the spherical coordinate system, that is, an XYZ rectangular coordinate system is established at the metasurface device, wherein the surface of the metasurface device forms an XY plane, the normal direction of the metasurface device is the Z axis, θ2 is the angle between the beam center pointing of the first outgoing signal and the normal (Z axis), is the angle between the projection of the beam center of the first outgoing signal on the XY plane and the positive direction of the X axis. It should be noted that, It can be the angle with the positive direction of the X-axis in the embodiment of the present invention, or it can be the angle with the negative direction of the X-axis, the positive direction or the negative direction of the Y-axis, which is only related to the definition method.

[0079] In the embodiment of the present invention, the unit phase value of each metasurface unit can be calculated by using the known first frequency, second frequency, first incident pitch angle, and first exit pitch angle.

[0080] Figure 4 This is an embodiment of spatial beam non-reciprocity pointing, which can be used to illustrate spatial beam non-reciprocity.

[0081] exist Figure 4 In the figure, the solid line represents the forward frequency conversion process, and the dotted line represents the backward frequency conversion process.

[0082] During forward frequency conversion, the frequency of the first incident signal is the first frequency, and the first incident pitch angle is θ1. After reflection by the non-reciprocal metasurface device described in any embodiment of the present invention, the frequency of the first output signal is the second frequency, and the first output pitch angle is θ2.

[0083] During backward frequency conversion, the frequency of the second incident signal is the second frequency, the second incident pitch angle is the same as the first exit pitch angle, which is θ2, and after reflection by the non-reciprocal metasurface device, the second exit pitch angle is θ3.

[0084] Since θ3≠θ1, non-reciprocal pointing of the spatial domain beam is achieved.

[0085] Figure 5(a) is a forward frequency conversion distribution diagram of a metasurface unit phase distribution and a spatial beam pointing embodiment, and Figure 5(b) is a backward frequency conversion distribution diagram of a metasurface unit phase distribution and a spatial beam pointing embodiment.

[0086] The left figure of Figure 5(a) is the phase distribution diagram of the metasurface unit during forward frequency conversion. The horizontal axis represents the unit in the x-axis direction, and the vertical axis represents the unit in the y-axis direction. The horizontal and vertical axes range from 1 to 12 units. The gradient scale bar on the right is the phase range. The right figure of Figure 5(a) shows the directional diagram of the first output pitch angle. The horizontal axis represents the angle size and the vertical axis represents the amplitude size.

[0087] The left figure of Figure 5(b) is the phase distribution diagram of the metasurface unit during backward frequency conversion. The horizontal axis represents the unit in the x-axis direction, and the vertical axis represents the unit in the y-axis direction. The horizontal and vertical axes range from 1 to 12 units. The gradient scale bar on the right is the phase range. The right figure of Figure 5(b) shows the direction diagram of the second output pitch angle. The horizontal axis represents the angle size and the vertical axis represents the amplitude size.

[0088] In an embodiment of the present invention, the dielectric substrate of the non-reciprocal metasurface uses Rogers 5880 material, with a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 1.575 mm. The central operating frequency of the metasurface is designed to be 2.5 GHz, the central frequency of the high-frequency end is designed to be 1.8 GHz, and the side length of the square copper radiation patch is 45 mm. The varactor diode in the time-varying modulation circuit adopts the Skyworks SMV1233 model, the inductor adopts a 20nH chip inductor, and the capacitor adopts a 5pF chip capacitor. The number of metasurface units is 12×12, and the unit spacing is 75 mm.

[0089] The DC bias voltage loaded by the designed modulation circuit is 1V, and the frequency of the time-varying modulation signal is f m =40MHz, modulation coefficient 0.17 (modulation signal amplitude 0.17V), the first incident pitch angle is 20 degrees, and the first exit pitch angle is 30 degrees.

[0090] During the test, in the forward frequency conversion process, the first incident pitch angle of the plane wave (first incident signal) irradiated in space is 20 degrees. The test results show that the first outgoing beam pointing direction is θ2 = 30 degrees, as shown in Figure 5(a). The design value is consistent with the measured value.

[0091] In the backward frequency conversion process, when the plane wave (second incident signal) irradiates the metasurface from θ2 = 30 degrees, the test shows that the main beam of the second output signal points to θ3 = 41 degrees, as shown in Figure 5(b).

[0092] It can be seen that θ3≠θ1, realizing the non-reciprocity of spatial domain beam pointing.

[0093] Figure 6 This is an embodiment of a non-reciprocal metasurface control method process, which can be used to implement the non-reciprocal metasurface device described in any embodiment of the present invention.

[0094] A non-reciprocal metasurface control method specifically comprises the following steps 101 to 103:

[0095] Step 101: Calculate the size and number of metasurface units according to the known metasurface operating frequency and the beam width of the first outgoing signal.

[0096] In step 101, the size of the metasurface unit and the number of the metasurface units can be calculated based on the known metasurface operating frequency and the beam width of the first output signal, thereby designing the structure of the overall metasurface.

[0097] Specifically, the size of the metasurface unit is approximately half the wavelength of the medium at the center operating frequency, and the number of metasurface units is calculated as follows:

[0098]

[0099]

[0100] Among them, N x is the number of x-axis units of the hypersurface, N y is the number of metasurface y-axis units, λ0 is the free space wavelength at the center operating frequency, is the 3dB beamwidth of the first outgoing signal in the X-axis direction, is the 3dB beamwidth of the first outgoing signal in the Y-axis direction.

[0101] It should be noted that the X-axis and the Y-axis can be freely set and are not particularly limited here. The beam width of the first outgoing signal refers to the 3dB beam width of the first outgoing signal, including the 3dB beam width in the X-axis direction and the 3dB beam width in the Y-axis direction.

[0102] Step 102: Calculate the unit phase value of each metasurface unit according to the first incident pitch angle of the first incident signal and the first exit pitch angle of the first exit signal, wherein the first incident signal is the incident signal during forward frequency conversion.

[0103] The formula for calculating the unit phase value of each metasurface unit in step 102 is as shown in formulas 1 to 3, which will not be repeated here.

[0104] Step 103: Determine the phase of the time-varying modulation signal according to the relationship between the phase value of the time-varying modulation signal and the unit phase value during forward frequency conversion and backward frequency conversion.

[0105] In step 103, the phase value of the time-varying modulation signal is determined according to the relationship between the phase value of the time-varying modulation signal and the unit phase value during forward frequency conversion, and the first incident elevation angle and the second incident elevation angle.

[0106] In step 103, the specific process of determining the phase value of the time-varying modulation signal has been described in detail in the embodiment of the device of the present invention, and will not be repeated here.

[0107] Furthermore, the method also includes: selecting a reasonable DC bias voltage, a time-varying modulation signal frequency, and a modulation coefficient, and controlling the phase value of the time-varying modulation signal fed into the modulation signal port of each metasurface unit according to the phase value of the time-varying modulation signal of each metasurface unit.

[0108] It should be noted that the modulation coefficient refers to the amplitude modulation coefficient of the time-varying modulation signal, that is, the ratio of the amplitude average of the time-varying modulation signal to the DC bias voltage.

[0109] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity 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, commodity or device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0110] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A non-reciprocal metasurface device, characterized in that: Contains a metasurface unit; Each metasurface unit is composed of a three-layer structure of a radiation patch, a dielectric substrate and a metal backplane, wherein the radiation patch is on the top surface of the dielectric substrate and the metal backplane is on the bottom surface of the dielectric substrate; The metasurface unit is used to load different unit phase values ​​according to the phase value of the time-varying modulation signal during forward frequency conversion and backward frequency conversion, so as to achieve non-reciprocity of beam pointing; The forward frequency conversion is a conversion of a first frequency into a second frequency, the backward frequency conversion is a conversion of a second frequency into a first frequency, the time-varying modulation signal is a sinusoidal signal, and the frequency of the time-varying modulation signal is a frequency difference between the first frequency and the second frequency; The metal backplane contains a feeding circuit, and the feeding circuit includes: a one-to-two power division network, first and second metallized through holes, a time-varying modulation signal feeding port, first and second inductors, first and second capacitors, and first and second varactor diodes; The first and second metallized through holes are used to connect the two ends of the one-to-two power splitting network to the edge of the radiation patch; The time-varying modulation signal feeding port is located at the input end of the one-to-two power division network, and the time-varying modulation signal enters the one-to-two power division network through the time-varying modulation signal feeding port; When performing forward frequency conversion, the first incident signal passes through the first metallized through hole and the first inductor to the first varactor diode, is mixed with the time-varying modulation signal, and then the low-frequency signal is isolated through the first capacitor, and then passes through the second capacitor, the second varactor diode and the second inductor to the second metallized through hole, and the first output signal is output; When performing backward frequency conversion, the second incident signal passes through the second metallized through hole and the second capacitor to the second varactor diode, is mixed with the time-varying modulation signal, and then the high-frequency signal is isolated through the second inductor, and then passes through the first capacitor, the first varactor diode, and the first inductor to the first metallized through hole to output a second output signal; The frequencies of the first incident signal and the second output signal are both the first frequency, and the frequencies of the first output signal and the second incident signal are both the second frequency.

2. The non-reciprocal metasurface device according to claim 1, characterized in that: The non-reciprocal metasurface device is formed by uniformly arranging the metasurface units in a rectangular arrangement.

3. The non-reciprocal metasurface device according to claim 1, characterized in that: The size and number of the metasurface units are determined by the metasurface operating frequency and a preset directional angle of a first output signal, where the first output signal is an output signal during forward frequency conversion.

4. The non-reciprocal metasurface device according to claim 1, characterized in that: The metasurface unit adopts a square copper radiation patch and a copper metal back plate.

5. The non-reciprocal metasurface device according to claim 1, characterized in that: The frequency of the time-varying modulation signal is 40 MHz, the operating frequency of the metasurface is 2.5 GHz, and the dielectric substrate uses Rogers 5880 material with a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 1.575 mm.

6. The non-reciprocal metasurface device according to claim 2, characterized in that: The unit phase value of the metasurface unit is: in, i , j are the row and column numbers of the hypersurface unit, k 1. k 2 are the wave numbers of the signals with the first and second frequencies respectively, , are respectively a first incident pitch angle of the first incident signal and a first exit pitch angle of the first exit signal, is the first emission horizontal angle of the first emission signal, d is the unit spacing between metasurface units; The first incident signal is an incident signal when forward frequency conversion is performed, and the first output signal is an output signal when forward frequency conversion is performed.

7. The non-reciprocal metasurface device according to claim 4, characterized in that: The side length of the square copper radiation patch is 45 mm.

8. A non-reciprocal metasurface control method, using the device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Calculating the size and number of metasurface units according to a known metasurface operating frequency and a beam width of a first outgoing signal, wherein the first outgoing signal is an outgoing signal when forward frequency conversion is performed; Calculating a unit phase value of each metasurface unit according to a first incident pitch angle of a first incident signal and a first exit pitch angle of a first exit signal, wherein the first incident signal is an incident signal when forward frequency conversion is performed; The phase of the time-varying modulation signal is determined according to the relationship between the phase value of the time-varying modulation signal and the unit phase value during forward frequency conversion.

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