Power-consumption-free magnetic control programmable metasurface

Abstract

The invention discloses a power-consumption-free magnetic control programmable metasurface which comprises a magnetic switch and a metasurface parasitic matching structure on the upper layer, a dielectric layer on the middle layer and a metal ground on the lower layer. Through the metasurface parasitic matching structure, the on-off of the magnetic switch is matched to a 1-bit phase regulation state when a space wave is incident. The reconfigurable metasurface is programmed through a static magnetic field, the functions of wave beam regulation and control and the like in a power-consumption-free scene are achieved, the magnetic control metasurface is simple in structure and low in cost, tail bias circuit design is not needed, and meanwhile the problem of power consumption during large-scale layout of the programmable intelligent metasurface is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of phase programmable metasurfaces, and in particular relates to a power-saving magnetically controlled programmable metasurface. Background Art

[0002] Existing programmable metasurfaces are mainly in the experimental verification stage and still have many problems, especially when considering large-scale layout. In order to meet the bias needs of a large number of diodes such as PIN tubes laid out on its surface, complex bias circuit design is required to produce structures such as tail lines; at the same time, the regulation of the diode array will generate a lot of energy consumption, which will greatly limit its development and practical application.

[0003] Existing programmable metasurfaces are mainly electrically programmable metasurfaces. In order to realize the bias of surface diodes, they are often complex in structure and have tail bias circuit structures. At the same time, there are power consumption problems that are difficult to avoid when deploying on a large scale. In order to solve these problems, existing solutions use optically controlled metasurfaces and microwave wireless energy transmission metasurfaces to achieve tail removal of the structure; on the other hand, low-power SPST switches or field-effect transistors are used to achieve low-power solutions. However, these solutions all have obvious shortcomings.

[0004] Through the design of optically controlled metasurfaces and microwave wireless energy transmission metasurfaces, people have achieved the removal of bias circuits, that is, tail removal. However, due to the extremely low working efficiency of this wireless control method, the photo-controlled diodes and rectifier diodes used are often expensive, and additional complex control circuit designs need to be considered. When used on a large scale, power consumption and cost issues will be quite serious.

[0005] The power consumption of the metasurface can be reduced to a certain extent through low-power SPST and triode switches. Although the power consumption of the metasurface unit can be reduced by dozens or hundreds of times, in practical applications, considering the large-scale layout of the array, such as for a 100×100 array, even if each unit contains only one diode, the entire metasurface array will generate W-level power consumption. At the same time, due to the existence of its inherent electrical bias circuit, additional power supply layout needs to be considered when laying out the metasurface, which will limit the design scale, application and use of the metasurface. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a power-free magnetically controlled programmable metasurface. The reconfigurable metasurface is programmed by a static magnetic field to realize functions such as beam steering in power-free scenarios. The proposed magnetically controlled metasurface has a simple structure and low cost, and does not require a tail bias circuit design. At the same time, it also solves the power consumption problem of programmable intelligent metasurfaces during large-scale layout.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A power-free magnetically controlled programmable metasurface comprises a metal ground, a dielectric substrate and a surface array, wherein the surface array is composed of a plurality of units, each of the units comprises a first strip 1, a second strip 2, a first patch 3 and a second patch 4, wherein the first patch 3 and the second patch 4 are symmetrical about the y direction, and the first strip 1 and the second strip 2 are symmetrical about the x direction, the first patch 3 and the second patch 4 are arranged between the first strip 1 and the second strip 2, and connected by a reed switch 5, the two ends of the first strip 1 have a first extension portion A11 and a first extension portion B12 in a direction away from the second strip 2, and the two ends of the second strip 2 have a second extension portion A21 and a second extension portion B22 in a direction away from the first strip 1; in two adjacent units in the y direction, the first strip 1 of one unit is connected to the second strip 2 of the other unit through corresponding extensions to form a parasitic loop; the switching of the reed switch 5 is realized by magnetic field drive, so as to realize 1-bit programmable phase control of each unit without power consumption.

[0009] The x-direction length L1 of the first strip 1 and the second strip 2 is 11.0 mm;

[0010] The y-direction length L3 of the first extension portion A11, the first extension portion B12, the second extension portion A21 and the second extension portion B22 is 3.2 mm.

[0011] The total length L2 of the branches on both sides in the y direction is 3.7 mm.

[0012] The x-direction spacing Lg of the intermediate branches is 8.4 mm.

[0013] The direction of each extension portion is the y direction, that is, perpendicular to each strip, thereby forming the rectangular parasitic ring.

[0014] The first patch 3 and the second patch 4 are T-shaped, the middle branches are opposite and connected by the reed switch 5, and the branches on both sides extend in the direction of the first strip 1 and the second strip 2 respectively and have the same spacing with the first strip 1 and the second strip 2.

[0015] The lateral size of the surface array unit is 60×60 mm, and the unit period in the subarray is 12 mm, which is smaller than one tenth of the wavelength of the center frequency 2.45 GHz.

[0016] The dielectric layer is a 3 mm thick dielectric substrate, and the overall cross-section of the metasurface is 4.8 mm, i.e., 0.039λ.

[0017] The power-free magnetically programmed metasurface is modulated with the surrounding static magnetic field. When the static magnetic field is loaded, the two actuating reeds are attracted together, thereby realizing magnetic programming of the unit.

[0018] When the magnetic field component on the metasurface parallel to the reed switch reaches 15AT, the metasurface here will be excited by the magnetic field and turn on;

[0019] When a plane wave is incident on the metasurface, the reasonably distributed static magnetic field enables the reconfiguration and effective control of the electromagnetic wave without power consumption.

[0020] The metasurface is placed along the horizontal polarization, and the bar magnet is placed vertically just behind the bottom layer of the metasurface, so that the reed switch on the metasurface in the corresponding column of the top layer just in front is turned on;

[0021] By adjusting the number and position of the bar magnets, specific array encoding can be achieved.

[0022] Beneficial effects of the present invention:

[0023] The present invention uses RI-80 reed switches to achieve switching under magnetic field drive, and realizes 1-bit programmable phase control near 2.45GHz through external parasitic structures. Since the metasurface is driven by an external magnetic field, it can switch states through magnets, etc., to achieve zero-power electromagnetic reconfigurable control, solving the power consumption problem of large-scale layout of metasurfaces.

[0024] In addition, thanks to the design that does not require a bias structure, this type of unit has a simple structure and can be designed and implemented on a single-layer PCB board with a low profile. The magnetron diode used is less than 0.5 yuan per unit, which greatly reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the unit structure and mechanism; Figure 1 a is a schematic diagram of the structure of a 5×5 subarray; Figure 1 b is the top view and top view of the parasitic ring structure; Figure 1 c is the simulation model in HFSS; Figure 1 d is the reflection amplitude and phase of the unit under normal incidence during HFSS periodic boundary simulation; Figure 1 e is the reflection phase difference of the unit in two working states under different oblique incidence angles during periodic boundary simulation.

[0026] Figure 2 Schematic diagram of unit electric field and current distribution.

[0027] Figure 3 The figure shows the simulation array model and the actual schematic diagram.

[0028] Figure 4 Schematic diagram of the test environment.

[0029] Figure 5 This is a diagram of array encoding and electric field results.

[0030] Figure 6 Schematic diagram of the TRL calibration component and the extracted S-parameter results under ON and OFF conditions.

[0031] Figure 7 Schematic diagram of the ADS fitting equivalent circuit model.

[0032] Figure 8 Schematic diagram of the measured S21 and the fitted equivalent circuit S21 results. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0034] like Figure 1 As shown, the present invention designs a reactive magnetically controlled programmable metasurface unit, the unit structure is as follows Figure 1 As shown in a;

[0035] It can be seen that the unit is composed of three layers: upper, middle and lower. The upper layer is the magnetic switch and metasurface parasitic matching structure, the middle layer is the dielectric substrate, and the lower layer is the metal ground.

[0036] The surface array is composed of multiple units, each of which includes a first strip 1, a second strip 2, a first patch 3 and a second patch 4, the first patch 3 and the second patch 4 are symmetrical about the y direction, the first strip 1 and the second strip 2 are symmetrical about the x direction, the first patch 3 and the second patch 4 are arranged between the first strip 1 and the second strip 2, and are connected by a reed switch 5, the two ends of the first strip 1 have a first extension part A11 and a first extension part B12 in the direction away from the second strip 2, and the two ends of the second strip 2 have a second extension part A21 and a second extension part B22 in the direction away from the first strip 1; in two adjacent units in the y direction, the first strip 1 of one unit is connected to the second strip 2 of the other unit through corresponding extensions to form a parasitic loop; the switching of the reed switch 5 is realized by magnetic field drive, so as to realize 1-bit programmable phase control of each unit without power consumption.

[0037] In order to ensure the effectiveness and high precision of magnetostatic and electromagnetic control and to establish a stable magnetostatic and electromagnetic interaction link, a subwavelength unit design was adopted.

[0038] Figure 1 a shows a schematic diagram of the structure of a 5×5 subarray, whose lateral size is 60×60 mm and the unit period in the subarray is 12 mm, which is less than one tenth of the wavelength of the center frequency 2.45 GHz.

[0039] The metasurface unit has three layers in total. The top layer is a metasurface structure composed of a surface parasitic ring and a reed switch, the middle layer is a dielectric plate, and the bottom layer is a metal ground patch. The 3mm thick dielectric layer uses an SJ9102 ​​dielectric substrate with a dielectric constant of 10.2.

[0040] An RI-80 type reed switch is welded in the center of each unit, and the thickness of the diode is 1.8 mm, so the overall profile of the metasurface is only 4.8 mm, or 0.039 λ, which greatly facilitates its application layout.

[0041] The present invention adopts the design of high dielectric plate and parasitic metasurface structure. In addition, since the metasurface does not need to consider the design of bias circuit structure, the dielectric plate used only needs to be 3mm. Therefore, the overall cross-section of the metasurface is only 4.8mm, i.e. 0.039λ, which is greatly beneficial to its application layout.

[0042] Through the design of the parasitic loop, a resonance of 2.45 GHz is achieved, and the resonance perturbation is completed when the reed switch is on and off, thereby realizing 1-bit switching of the reflection phase.

[0043] In order to achieve a 1-bit phase response of the unit at a frequency of 2.45 GHz, a large number of simulation experiments were carried out on the metasurface parasitic loop matching structure.

[0044] Based on the above simulation, Figure 1 b is the top view and top view of the unit, showing the optimal size parameters of the parasitic ring structure. The lateral length L of the ring 1 =11.0mm, reed switch welding pin length L 2 = 3.7 mm, half of the longitudinal length of the ring L 3 =3.2mm, the ring width W = 0.8mm and Lg is 8.4mm. Through the design of the parasitic ring, a 2.45GHz resonance is achieved, and the resonance perturbation is completed in the on-off state of the reed switch, thereby realizing 1-bit switching of the reflection phase. Figure 1 As shown in b, the bottom layer of the unit is a fully metal ground. Due to the power-saving magnetic control characteristics of the unit, there is no need to design an additional complex bias circuit structure.

[0045] The reed switch used is a magnetically operated switch device, type RI-80, of single pole single throw (SPST) type, with normally open contacts, and containing two magnetically actuated reeds, such as Figure 1 As shown in a.

[0046] The device is suitable for use as a sensor, relay, pulse counter or similar device. The expected life of the reed switch under no-load conditions (operating frequency 100Hz) is at least 10 8 Operations with a failure rate of less than 2×10 -9, with a confidence level of 90%.

[0047] When it works at a load voltage of 5V, a current of 100mA and an operating frequency of 170Hz, the expected lifespan reaches 10 7 Operations with a failure rate of less than 10 -8 , with a confidence level of 90%. The reed switch conducts when the magnetic field is greater than 15AT and disconnects when the magnetic field is less than 2AT. The bounce time and release time of the diode are less than 0.1ms and 20us. When the reed switch is open, the DC resistance is less than 160 milliohms, and when it is closed, the DC impedance is greater than 10 6 Megohms. However, the RF impedance of the reed switch is unknown. In order to obtain the electromagnetic characteristics of the diode in the on and off states, the two-port S parameters on its end face are de-embedded and directly extracted using the TRL calibration method. The diode has stable amplitude and phase characteristics, can effectively realize the RF switching characteristics, and connect the static magnetic field with the RF under different external static magnetic field excitations. The measured S parameters are circuit fitted, and it is obtained that its equivalent circuit in the on state near 2.45GHz is a series circuit of 20pF, 4.9nH, 4.6ohm, and the equivalent circuit in the off state is a series circuit of 0.46pF, 4.1nH.

[0048] The simulation model in HFSS is as follows Figure 1 c. It can be seen as a cascade of air transmission line, surface switch, capacitive and inductive structure and short-circuited transmission line. Here, by designing the parasitic loop, specific parasitic capacitance and inductance are obtained, so that the magnetron and the air layer are matched at the target frequency, achieving 1-bit phase resolution in the resonant and switching states.

[0049] When the magnetic field strength around the unit is greater than 150 Gauss, the diode is turned on and the unit resonates around the 2.4 GHz center frequency. When it is turned off, the resonance occurs around 2.6 GHz. Figure 1 As shown in d and 1e, the perturbation of the resonant state causes the unit to undergo a phase change of 180°±20° near the center frequency of 2.45GHz with a bandwidth of 100MHz. At the same time, the low-loss characteristics of the unit can also be observed. In both states, the insertion loss of the component within the operating frequency band is less than 1dB. In addition, the 1-bit phase mutation in the frequency domain at different incident angles is also studied. It can be seen that the component exhibits good angular stability. When the incident angle increases from 0° to 30°, it can be ensured that the phase change within the target frequency band is 180°±20°.

[0050] Changes in the RF characteristics of the cell can also be qualitatively observed from the cell's electric field and current distribution. Figure 2The electric field distribution and current direction on the surface of the unit in the on and off states are shown. When operating in the on state, a large amount of current is induced in the reed switch and flows in the y direction. When the diode is off, the current path in the center is almost cut off, and only a part of the current flows in the parasitic loop, resulting in a weaker center of the resonant response.

[0051] Unlike traditional electronically programmable metasurface elements, this magnetically actuated programmable metasurface unit does not need to load PIN diodes or varactor diodes to achieve resonant tuning under different bias voltages, but switches its working state under different static magnetic field drives. Compared with existing programmable metasurfaces, this type of metasurface has three significant features: structurally, it does not require the design of a bias structure, realizing a truly tailless reconfigurable metasurface; in terms of driving mode, the static magnetic field modulates the electromagnetic scattering field; when it comes to specific applications, there is no need to consider DC bias and power consumption requirements.

[0052] According to the diffraction grating theory, the periodic modulated surface exhibits a spatial spectrum modulation effect on electromagnetic waves. This power-free magnetically controlled programming metasurface can be modulated by the surrounding static magnetic field, such as Figure 1 As shown in the figure, when the magnetic field component on the metasurface parallel to the reed switch reaches 15AT, the metasurface here will be excited by the magnetic field and turned on. In other words, when a plane wave is incident on the metasurface, a reasonably distributed static magnetic field can realize the reconfiguration and effective control of electromagnetic waves under zero power consumption conditions. Based on the unit design, the unit was analyzed for array formation and actual array processing, and its wavefront phase control was tested to verify its zero-power electromagnetic beam control function. The array was assembled through the periodic arrangement of 12mm units. The array model diagram is similar to the actual processed array as shown in the figure. Figure 3 As shown in the figure, the darkroom test environment is as follows Figure 4 shown.

[0053] like Figure 4 As shown, when the metasurface is placed along the horizontal polarization and the bar magnet is placed vertically 50 mm behind the metasurface, the reed switches on the three rows of metasurfaces in front can be turned on. By adjusting the number and position of the magnets, specific array encoding can be achieved.

[0054] First, the beam deflection simulation was realized on a 32×32 array scale. The size of the established array is 384×384mm. 2 Here, assuming that the plane wave is excited vertically, the coding states under three different target exit angles are simulated. The coding states are as follows: Figure 5 As shown in Figure ac, brown represents off and yellow represents on. Figure 5 df gives the corresponding real part of the electric field on the horizontal plane perpendicular to the array, through which the change of the waveform can be observed. Figure 5The far-field results of g show that the scanned beam is accurately directed to 20, 40, and 50 degrees.

[0055] Therefore, the metasurface can achieve 1-bit phase modulation and reconfigurable beam control without power consumption through magnetic programming reconfiguration, solving the problems of bias design and high power consumption when the metasurface is deployed on a large scale.

[0056] The present invention realizes 1-bit control phase switching of the metasurface unit by means of magnetic field driving. Among them, the unit adopts RI-80 reed switch as the magnetically controlled switch, which is not the only one. This diode is just used as a typical example here. In fact, other reed switches such as MKA14103 can be used to complete the design implementation. They only need to be designed with their own parasitic structure to achieve impedance matching from the load end to the air. The square ring parasitic structure used here is just a series capacitor and inductor structure, which can be adjusted in the alternative scheme.

[0057] The reed switch can achieve good on-off switching at DC frequency, and it can also achieve similar switching effects at RF frequency.

[0058] First, a TRL calibration component is designed to extract the S parameters of the diode after de-embedding. The calibration component structure is as follows: Figure 6 As shown. First, use the vector network analyzer to perform de-embedding operations through the designed "Thru", "Reflect", and "Line" calibration components, and finally measure the S parameters of the diode soldered on the "DUT" component to obtain the S parameters when it is turned on by magnetic excitation and when it is not turned on without magnetic excitation. Figure 7 , Figure 8 is the extracted S parameter result. From this result, we can know that the reed switch effectively connects the external static magnetic field excitation with the RF on-off. (On this basis, through the design of the metasurface unit parasitic patch, the static magnetic field excitation is effectively connected with the 1-bit phase modulation of the RF).

[0059] In order to quickly simulate the magnetron metasurface, based on the extracted S parameters of the diode, an equivalent circuit fitting was performed on the diode in the target frequency band near 2.45 GHz. Figure 7 As shown, in the ADS circuit simulation software, the simulation Figure 7 The S parameters of the four circuits a, b, c, and d are shown in Figure 8. Among them, a and c are the S2P results of the on and off conditions measured after TRL calibration, respectively. B and d are the corresponding fitted equivalent circuit models, respectively. The final fitting results are shown in Figure 8. It can be seen that the fitted equivalent circuit is basically consistent with the measured S21 in amplitude and phase.

Claims

1. A power-free magnetically controlled programmable metasurface, comprising a metal ground, a dielectric substrate, and a surface array, wherein the surface array is composed of a plurality of units, characterized in that: Each of the units comprises a first strip (1), a second strip (2), a first patch (3) and a second patch (4); the first patch (3) and the second patch (4) are symmetrical about the y direction, the first strip (1) and the second strip (2) are symmetrical about the x direction, the first patch (3) and the second patch (4) are arranged between the first strip (1) and the second strip (2) and are connected through a reed switch (5); the two ends of the first strip (1) have a first extension part A (11) and a first extension part B (12) in a direction away from the second strip (2), and the two ends of the second strip (2) have a second extension part A (21) and a second extension part B (22) in a direction away from the first strip (1); in two adjacent units in the y direction, the first strip (1) of one unit and the second strip (2) of the other unit are connected through corresponding extension parts to form a parasitic loop; the switching of the reed switch (5) is realized by magnetic field drive, so as to realize 1-bit programmable phase control of each of the units without power consumption.

2. The zero-power magnetically controlled programmable metasurface according to claim 1, characterized in that: The first patch (3) and the second patch (4) are T-shaped, with the middle branches facing each other and connected via a reed switch (5), and the branches on both sides extend in the direction of the first strip (1) and the second strip (2) respectively and have the same spacing with the first strip (1) and the second strip (2).

3. The zero-power magnetically controlled programmable metasurface according to claim 2, characterized in that: The x-direction length L1 of the first strip (1) and the second strip (2) is 11.0 mm; The y-direction length L3 of the first extension portion A (11), the first extension portion B (12), the second extension portion A (21) and the second extension portion B (22) is 3.2 mm. The total length L2 of the branches on both sides in the y direction is 3.7 mm; The x-direction spacing Lg of the intermediate branches is 8.4 mm.

4. The zero-power magnetically controlled programmable metasurface according to claim 3, characterized in that: The direction of each extension portion is the y direction, that is, perpendicular to each strip, thereby forming the rectangular parasitic ring.

5. The zero-power magnetically controlled programmable metasurface according to claim 3, characterized in that: The lateral size of the subarray unit is 60×60 mm, and the unit period in the subarray is 12 mm, which is smaller than one tenth of the wavelength of the center frequency 2.45 GHz.

6. The zero-power magnetically controlled programmable metasurface according to claim 1, characterized in that: The dielectric layer is a 3 mm thick dielectric substrate, and the overall cross-section of the metasurface is 4.8 mm, i.e., 0.039λ.

7. The application of a power-free magnetically controlled programmable metasurface according to any one of claims 1 to 6, characterized in that: The power-free magnetically controlled programming metasurface is modulated by the surrounding static magnetic field. When the static magnetic field is loaded, the two actuating reeds are attracted together, thereby realizing the magnetic programming of the unit.

8. The application of a power-saving magnetically controlled programmable metasurface according to claim 7, characterized in that: When the magnetic field component on the metasurface parallel to the reed switch reaches 15AT, the metasurface here will be excited by the magnetic field and turn on; When a plane wave is incident on the metasurface, the reasonably distributed static magnetic field enables the reconfiguration and effective control of the electromagnetic wave without power consumption.

9. The application of a power-free magnetically controlled programmable metasurface according to claim 7, characterized in that: The metasurface is placed along the horizontal polarization, and the bar magnet is placed vertically just behind the bottom layer of the metasurface, so that the reed switch on the metasurface in the corresponding column of the top layer just in front is turned on; Specific array encoding can be achieved by adjusting the number and position of bar magnets.

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