A power-free magnetically controlled programmable metasurface

Abstract

This invention discloses a power-free, magnetically controlled programmable metasurface, comprising an upper layer of magnetic switches and a parasitic matching structure for the metasurface, a middle layer of dielectric material, and a lower layer of metallic ground. Through the parasitic matching structure, the on / off state of the magnetic switches is matched to a 1-bit phase modulation state when a space wave is incident. This invention programs the reconfigurable metasurface using a static magnetic field, achieving beam control and other functions in power-free scenarios. The proposed magnetically controlled metasurface structure is simple, low-cost, and eliminates the need for a tail bias circuit design, while also solving the power consumption problem in large-scale deployment of programmable intelligent metasurfaces.

Description

Technical Field

[0001] This invention belongs to the field of phase-programmable metasurface technology, specifically relating to a power-free magnetically controlled programmable metasurface. Background Technology

[0002] Existing programmable metasurfaces are mainly in the experimental verification stage and still have many problems. In particular, when considering large-scale layout, in order to meet the biasing requirements of a large number of diodes such as PIN diodes on the surface, complex biasing circuit designs are required, resulting in structures such as tail lines. At the same time, the control 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. To achieve the biasing of surface diodes, they often have complex structures with tail biasing circuits. Furthermore, power consumption issues are unavoidable when deploying them on a large scale. To address these problems, existing solutions employ optically controlled metasurfaces and microwave wireless power transfer metasurfaces to eliminate the tail of the structure; alternatively, low-power SPST switches or field-effect transistors are used to achieve low-power solutions. However, these solutions all have significant shortcomings.

[0004] By designing light-controlled metasurfaces and microwave wireless power transmission metasurfaces, the bias circuit has been eliminated, or tail-free. However, this wireless control method suffers from extremely low efficiency. Furthermore, the light-controlled diodes and rectifier diodes used are often expensive, and additional complex control circuit designs are required. Therefore, power consumption and cost issues will be quite serious when used on a large scale.

[0005] The power consumption of metasurfaces can be reduced to some extent by using low-power SPSTs, transistor switches, and other methods. Although the power consumption of metasurface cells can be reduced by tens or hundreds of times, in practical applications, considering the large-scale layout of the array, such as a 100×100 array, even if each cell contains only one diode, the entire metasurface array will still generate power consumption in the watt range. Furthermore, due to the inherent electrical bias circuitry, additional power supply layouts need to be considered when laying out metasurfaces, which limits the design scale, application, and use of metasurfaces. Summary of the Invention

[0006] To overcome the shortcomings of the existing technology, the present invention aims to provide a power-free magnetically controlled programmable metasurface. By programming the reconfigurable metasurface with a static magnetic field, functions such as beam control in power-free scenarios are realized. The proposed magnetically controlled metasurface has a simple structure, low cost, and does not require tail bias circuit design. It also solves the power consumption problem when deploying programmable smart metasurfaces on a large scale.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A power-free, magnetically controlled, programmable metasurface includes a metal ground, a dielectric substrate, and a surface array. The surface array consists of multiple units, each unit including 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, 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 A11 and a first extension B12 in the direction away from the second strip 2, and the two ends of the second strip 2 have a second extension A21 and a second extension 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 and the second strip 2 of the other unit are connected by corresponding extensions to form a parasitic loop. The switching of the reed switch 5 is achieved by magnetic field drive, realizing 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 A11, the first extension B12, the second extension A21, and the second extension B22 is 3.2 mm.

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

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

[0013] The direction of each extension is 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, with the middle branches facing each other and connected by a reed switch 5. The branches on both sides extend towards the first strip 1 and the second strip 2 respectively, and have the same spacing as the first strip 1 and the second strip 2.

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

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

[0017] The power-free magnetically programmable metasurface is modulated by the surrounding static magnetic field. When the static magnetic field is applied, two actuating reeds will attract together, thereby realizing the magnetic programming of the cell.

[0018] When the magnetic field component parallel to the reed switch on the metasurface reaches 15AT, the metasurface at this point will be excited by the magnetic field and become conductive.

[0019] When a plane wave is incident on the metasurface, a reasonably distributed static magnetic field enables the reconfigurability and effective control of the electromagnetic wave under power-free conditions.

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

[0021] Specific array coding can be achieved by adjusting the number and position of the bar magnets.

[0022] The beneficial effects of this invention are:

[0023] This invention utilizes an RI-80 reed switch to achieve magnetic field-driven switching and, through an external parasitic structure, achieves 1-bit programmable phase modulation around 2.45 GHz. Since this metasurface is driven by an external magnetic field, its state can be switched using magnets, achieving zero-power electromagnetic reconfigurable control and solving the power consumption problem of large-scale metasurface deployments.

[0024] Furthermore, 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; and the magnetic control diode used costs less than 0.5 yuan per unit, which greatly reduces the cost. Attached Figure Description

[0025] Figure 1 This is a 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 shows the top and top views of the parasitic ring structure; Figure 1 c represents the simulation model in HFSS; Figure 1 d represents the reflection amplitude and phase of the element under normal incidence during HFSS periodic boundary simulation; Figure 1 e represents the reflection phase difference of the element under two working states when incident at different angles during periodic boundary simulation.

[0026] Figure 2 This is a schematic diagram of the electric field and current distribution of a single unit.

[0027] Figure 3 This is a simulation array model and a schematic diagram of the actual object.

[0028] Figure 4 This is a schematic diagram of the test environment.

[0029] Figure 5 The diagram shows the array encoding and electric field results.

[0030] Figure 6 This is a schematic diagram showing the TRL calibration kit and the extracted S-parameter results under ON and OFF conditions.

[0031] Figure 7 A schematic diagram of the equivalent circuit model fitted by ADS.

[0032] Figure 8 This is a schematic diagram showing the measured S21 and the fitted equivalent circuit S21. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

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

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

[0036] The surface array is composed of multiple units, each unit including 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, 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 A11 and a first extension B12 in the direction away from the second strip 2, and the two ends of the second strip 2 have a second extension A21 and a second extension 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 and the second strip 2 of the other unit are connected by corresponding extensions to form a parasitic loop. The switching of the reed switch 5 is realized by magnetic field drive, realizing 1-bit programmable phase control of each unit without power consumption.

[0037] 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 Figure a shows a schematic diagram of a 5×5 subarray, with a horizontal dimension of 60×60mm. The cell period in the subarray is 12mm, which is less than one-tenth of the wavelength of the center frequency of 2.45GHz.

[0039] This metasurface unit consists of three layers: the top layer is a metasurface structure composed of surface parasitic rings and reed switches; the middle layer is a dielectric substrate; and the bottom layer is a metal ground sheet. The 3mm thick dielectric layer uses an SJ9102 ​​dielectric substrate with a dielectric constant of 10.2.

[0040] The RI-80 type reed switch is welded to the center of each unit, and the diode is 1.8mm thick. Therefore, the overall cross-section of the metasurface is only 4.8mm, or 0.039λ, which greatly benefits its application layout.

[0041] This invention utilizes a high-dielectric substrate and a parasitic metasurface structure design. Furthermore, since the metasurface does not require the design of a bias circuit structure, the dielectric substrate used is only 3mm thick. Therefore, the overall cross-section of the metasurface is only 4.8mm, or 0.039λ, which greatly benefits its application layout.

[0042] Through the design of this parasitic ring, a 2.45 GHz resonance was achieved, and the resonant perturbation was completed under the on and off states of the reed switch, thereby realizing 1-bit switching of the reflection phase.

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

[0044] Based on the above simulation, such as Figure 1 b shows the top and bottom views of the unit, illustrating the optimal dimensional parameters of the parasitic ring structure. The ring's lateral length L1 = 11.0 mm, reed switch solder pin length L2 = 3.7 mm, half the ring's longitudinal length L3 = 3.2 mm, ring width W = 0.8 mm, and Lg = 8.4 mm. This parasitic ring design achieved 2.45 GHz resonance and completed resonant perturbation under reed switch on / off conditions, thereby realizing 1-bit switching of the reflection phase. Figure 1 As shown in b, the bottom layer of the cell is an all-metal ground. Due to the cell's power-free magnetic control characteristics, there is no need to design an additional complex bias circuit structure.

[0045] The reed switch used is a magnetically controlled switch device, type RI-80, a 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] This device is suitable for sensors, relays, pulse counters, or similar devices. The expected lifespan of the reed switch under no-load conditions (operating frequency 100Hz) is at least 10... 8 The failure rate is less than 2×10⁻⁶ per operation. -9 The confidence level is 90%.

[0047] When operating at a load voltage of 5V, a current of 100mA, and an operating frequency of 170Hz, its expected lifespan is 10 years. 7 The failure rate is less than 10% after one operation. -8 The confidence level is 90%. The reed switch conducts when the magnetic field is greater than 15AT and opens when the magnetic field is less than 2AT. The diode's bounce time and release time are less than 0.1ms and 20us, respectively. When the reed switch is open, the DC resistance is less than 160 milliohms, and when closed, the DC impedance is greater than 10 ohms. 6 Megohms. However, the RF impedance of the reed switch is unknown. To obtain the electromagnetic characteristics of the diode in both on and off states, the S-parameters of its two terminals were directly extracted using the TRL calibration method. The diode exhibits stable amplitude and phase characteristics, effectively realizing RF switching characteristics and connecting the static magnetic field to the RF under different external static magnetic field excitations. Circuit fitting was performed on the measured S-parameters, yielding an equivalent circuit of 20pF, 4.9nH, and 4.6 ohms in the on state near 2.45 GHz, and an equivalent circuit of 0.46pF and 4.1nH in the off state.

[0048] Simulation models in HFSS, such as Figure 1 As shown in c, it can be viewed as a cascade of an air transmission line, a surface switch, a capacitive structure, and a short-circuit transmission line. Here, by designing a parasitic loop, specific parasitic capacitance and inductance are obtained, thereby matching the magnetron and the air layer at the target frequency, achieving 1-bit phase resolution in both resonant and switching states.

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

[0050] The changes in the radio frequency characteristics of this unit can also be qualitatively observed from the electric field and current distribution of the unit. Figure 2The electric field distribution and current direction on the surface of the unit are shown in the on and off states. When operating in the on state, a large current is induced in the reed switch and flows along the y-direction. When the diode is off, the current path at the center is almost cut off, and only a portion of the current flows on the parasitic loop, resulting in a weaker center of the resonant response.

[0051] Unlike traditional electronically programmable metasurface elements, this magnetically excited programmable metasurface unit does not require PIN diodes or varactor diodes to achieve resonant tuning under different bias voltages. Instead, it switches its operating state under different static magnetic fields. Compared to existing programmable metasurfaces, this type of metasurface has three significant characteristics: structurally, it does not require a bias structure design, realizing a truly tailless reconfigurable metasurface; in terms of driving mode, the static magnetic field modulates the electromagnetic scattering field; and when it comes to specific applications, DC bias and power consumption requirements are no longer a concern.

[0052] According to diffraction grating theory, periodically modulated surfaces exhibit spatial spectral modulation effects on electromagnetic waves. This power-free, magnetically programmable metasurface can be modulated using an surrounding static magnetic field, such as... Figure 1 As shown, when the magnetic field component parallel to the reed switch on the metasurface reaches 15 AT, the metasurface will be excited by the magnetic field and become conductive. That is, when a plane wave is incident on this metasurface, a reasonably distributed static magnetic field can achieve reconfigurable and effective control of the electromagnetic wave under zero-power conditions. Based on the unit design, array analysis and actual array fabrication were performed on the unit, and tests were conducted on its wavefront phase modulation to verify its zero-power electromagnetic beam modulation function. An array was constructed using a periodic arrangement of 12mm units. The array model diagram and the actual fabricated array are shown below. Figure 3 As shown, the anechoic chamber testing environment is as follows: Figure 4 As shown.

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

[0054] First, beam deflection simulation was performed on a 32×32 array, with the established array size being 384×384mm. 2 Here, assuming the plane wave is vertically excited, the encoded states are simulated under three different target exit angles. The encoded states are as follows: Figure 5 As shown in ac, brown represents off and yellow represents on. Figure 5 df gives the real part of the electric field on the horizontal plane perpendicular to the array. This result allows observation of the waveform changes. Figure 5The far-field results for g show that the scanning beam is precisely oriented to 20, 40, and 50 degrees.

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

[0056] This invention achieves 1-bit phase switching of a metasurface unit through magnetic field driving. The unit uses an RI-80 reed switch as a magnetic switch, but this is not the only option; it is simply used as a typical example. In fact, other reed switches such as the MKA14103 can also be used to achieve this design, requiring only individual parasitic structure design to achieve impedance matching from the load to air. The square ring parasitic structure used here is simply a series capacitor-inductor structure, which can be adjusted in alternative solutions.

[0057] Reed switches can achieve good on / off switching at DC frequencies, and they can also achieve a similar switching effect at radio frequency frequencies.

[0058] First, a TRL calibration device was designed to extract the S-parameters of a de-embedded diode. The structure of the calibration device is as follows: Figure 6 As shown. First, using a vector network analyzer, de-embedding operations are performed through pre-designed "Thru," "Reflect," and "Line" calibration components. Finally, the S-parameters of the diodes soldered onto the "DUT" are measured, obtaining the S-parameters for both magnetic excitation-induced conduction and non-magnetic excitation-induced non-conduction. For example... Figure 7 , Figure 8 The extracted S-parameter results are shown. These results demonstrate that the reed switch effectively connects the external static magnetic field excitation with the radio frequency on / off state. (Based on this, the design of the metasurface unit parasitic patch effectively links the static magnetic field excitation with the 1-bit phase modulation of the radio frequency).

[0059] To facilitate rapid simulation of the magnetron-controlled metasurface, an equivalent circuit fit was performed on the diode in the target frequency band near 2.45 GHz, based on the extracted S-parameters. For example... Figure 7 As shown, the circuit simulations were performed in the ADS circuit simulation software. Figure 7 The S-parameters of four circuits, a, b, c, and d, are shown in Figure 8. Here, a and c represent the S2p results measured after TRL calibration under on and off states, respectively, while b and d represent the corresponding fitted equivalent circuit models. 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 multiple units forming sub-array units, characterized in that, Each unit 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, 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 A (11) and a first extension B (12) in the direction away from the second strip (2). The two ends of the second strip (2) have a second extension A (21) and a second extension B (22) in the 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 by corresponding extensions to form a parasitic loop. The switching of the reed switch (5) is realized by using a magnetic field drive, realizing 1-bit programmable phase control of each unit without power consumption. The first patch (3) and the second patch (4) are T-shaped, with the middle branches facing each other and connected by a reed switch (5), and the branches on both sides extending in the direction of the first strip (1) and the second strip (2) respectively, and having the same spacing as the first strip (1) and the second strip (2); Each extension is oriented in the y-direction and is perpendicular to each strip, thereby forming the rectangular parasitic ring.

2. The power-free, magnetically controlled, programmable metasurface according to claim 1, 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 A (11), the first extension B (12), the second extension A (21), and the second extension B (22) is 3.2 mm; The total y-direction length L2 of the two branches is 3.7 mm; The x-axis spacing Lg of the intermediate branches is 8.4 mm.

3. The power-free, magnetically controlled, programmable metasurface according to claim 2, characterized in that, The subarray unit has a lateral dimension of 60×60mm, and the unit period in the subarray is 12mm, which is less than one-tenth of the wavelength of the center frequency of 2.45GHz.

4. The power-free, magnetically controlled, programmable metasurface according to claim 1, characterized in that, The dielectric substrate is 3 mm thick, and the overall cross-section of the metasurface is 4.8 mm thick.

5. The application of a power-free, magnetically controlled, programmable metasurface according to any one of claims 1-4, characterized in that, The power-free magnetically controlled programmable metasurface is modulated by the surrounding static magnetic field. When the static magnetic field is applied, two actuating reeds will attract together, thereby realizing the magnetic programming of the cell.

6. The application of the power-free magnetically controlled programmable metasurface according to claim 5, characterized in that, When the magnetic field component parallel to the reed switch on the metasurface reaches 15AT, the metasurface at this point will be excited by the magnetic field and become conductive. When a plane wave is incident on the metasurface, a reasonably distributed static magnetic field can change the state of the metasurface without power consumption, thereby enabling the reconfigurability and effective control of electromagnetic waves.

7. The application of the power-free magnetically controlled programmable metasurface according to claim 5, characterized in that, The metasurface is placed with horizontal polarization, and the bar magnet is placed vertically behind the bottom layer of the metasurface, so that the reed switch on the corresponding column of the top layer of the metasurface is turned on. Specific array coding can be achieved by adjusting the number and position of bar magnets.

Images