Shielding electromagnetic metamaterial based on slotted mushroom-type AMC structure

Abstract

The application discloses a shielding electromagnetic metamaterial based on a slotted mushroom type AMC structure, which is composed of m x m slotted mushroom type AMC arrays of slotted mushroom type AMC units, the slotted mushroom type AMC unit comprises, from top to bottom, a top patch, a middle dielectric layer and a bottom patch; the center of the top patch is connected to the center of the bottom patch through a metal through hole penetrating through the middle dielectric layer; the top patch is provided with a slotted groove on the surface and is arranged on the front surface of the middle dielectric layer; and the bottom patch is arranged on the back surface of the dielectric layer. The application can realize magnetic field shielding and high-efficiency energy transmission of a wireless power transmission system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wireless energy transmission, and particularly relates to a shielding electromagnetic metamaterial based on a slotted mushroom type AMC structure. BACKGROUND

[0002] Wireless energy transmission technology is a new technology that transmits energy from the transmitter to the receiver through electromagnetic coupling without any physical connection, thereby realizing wireless energy supply. This technology has a wide application prospect in electric vehicle charging, wireless device power supply, medical devices, smart home, etc. In particular, a magnetic coupling resonance type wireless energy transmission system (MCR-WPT) is usually composed of a transmitter and a receiver. The transmitter generates an alternating magnetic field in the coil through the current, and the receiver receives this magnetic field through the coil and converts it into electric energy, thereby realizing wireless energy transmission. Due to its long transmission distance, high efficiency and large power, it has become a research hotspot. However, such a system will produce strong electromagnetic radiation during operation, and will waste electromagnetic energy to areas that do not need it, resulting in a decrease in energy transmission efficiency in the required area. Therefore, suppressing electromagnetic radiation, reducing electromagnetic energy dissipation and improving energy transmission efficiency are current problems to be solved.

[0003] In order to solve the electromagnetic radiation problem in wireless energy transmission systems such as MCR-WPT, existing technical solutions mainly focus on the use of various electromagnetic shielding materials. For example, the combination of negative magnetic and zero magnetic metamaterials is used in a wireless power transmission system performance improvement device, which effectively suppresses electromagnetic radiation and improves system performance. However, these metamaterials often have problems such as complex manufacturing, high cost, and coupling effect between the coil, which reduces the efficiency of the wireless energy transmission system. Another method is to use metal materials such as copper, aluminum, etc. They reflect and absorb electromagnetic waves to achieve the purpose of shielding electromagnetic interference. Or use a low magnetic permeability metamaterial of a metal coil array, which can adjust the magnetic permeability of the metamaterial by changing the shape and size of the metal coil, thereby effectively suppressing electromagnetic radiation. However, this method also has the disadvantages of difficult adjustment and poor adaptability.

[0004] In addition to shielding materials, microwave absorbing material technology is also an important means of reducing electromagnetic radiation. Such materials can absorb electromagnetic waves and reduce electromagnetic reflection, thereby improving the efficiency of the wireless energy transmission system. However, traditional microwave absorbing materials have large losses and are not suitable for high-efficiency wireless energy transmission systems. This limitation makes it necessary to find new absorbing materials for high-efficiency energy transmission systems.

[0005] In addition, using metal mesh structure or magnetic material as electromagnetic shielding material, the shielding effect can also be achieved by changing the structure and proportion of these materials. For example, the metal mesh structure can adjust the shielding effect by changing its shape and size, while the magnetic material can shield electromagnetic radiation by adjusting the type and proportion. However, these schemes are often limited in practical application due to complex structure or high material cost, which is difficult to promote on a large scale.

[0006] The prior art has the disadvantages of large volume, unsuitability for miniaturization and integration of equipment, high manufacturing cost, large loss, complex design and generation of additional electromagnetic radiation when dealing with electromagnetic radiation problems in wireless energy transmission systems. Due to these problems, the effectiveness of the prior art in large-scale application and high-efficiency energy transmission is limited, which is not conducive to the widespread promotion and efficient operation of the system. SUMMARY

[0007] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a shielding electromagnetic metamaterial based on a slotted mushroom-type AMC structure, which can realize magnetic field shielding and high-efficiency energy transmission for a wireless energy transmission system.

[0008] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0009] A shielding electromagnetic metamaterial based on a slotted mushroom-type AMC structure, which is composed of an m x m array of slotted mushroom-type AMC units, the slotted mushroom-type AMC unit includes a top patch, an intermediate dielectric layer and a bottom patch arranged in order from top to bottom.

[0010] The center of the top patch is connected to the center of the bottom patch through a metal through hole passing through the intermediate dielectric layer; the top patch has a surface slotted groove, and the top patch is arranged on the front surface of the intermediate dielectric layer; the bottom patch is arranged on the back surface of the dielectric layer.

[0011] The electromagnetic wave is set to be vertically incident on the top patch, the current generated is flowed to the bottom patch to form an equivalent inductance L, and a slot capacitance C is formed in the surface slotted groove of the top patch.

[0012] According to the equivalent circuit theory, if the resonance frequency is f, the surface impedance of the structure and the resonance frequency point are respectively:

[0013]

[0014] Determine any three structural parameters of the slotted mushroom-type AMC unit, and determine the remaining one structural parameter according to the relationship between the slotted mushroom-type AMC structural parameters and the slot capacitance C and the equivalent inductance L:

[0015]

[0016] L = μ0h

[0017] wherein ε0 and μ0 are the vacuum permittivity and vacuum permeability, respectively, the permittivity of the intermediate dielectric layer is μ r , the thickness is h, the patch cell side length of the top patch and the bottom patch is Wl, the slot gap side length of the slot is sl, the slot gap width is sw, and the cell spacing is gl.

[0018] From the above formula, when the slotted mushroom-shaped AMC structure is incident by an electromagnetic wave with a resonant frequency of f, the surface impedance is infinite, at which time the surface of the slotted mushroom-shaped AMC structure can be approximated as an ideal magnetic surface (PMC).

[0019] The slot gap coupling capacitance formed by the top patch slot structure replaces the lumped capacitance, the slot gap width sw of the slot is in the range of 8mm to 12mm, the shape of the slot gap is square or circular arc, and the metal via connects the top patch to form a mushroom shape.

[0020] The slotted slot and the top patch are symmetrical about the horizontal axis or the vertical axis, and can be flexibly moved according to different systems, thereby reducing the design complexity and processing difficulty of the AMC and improving the manufacturing efficiency. The horizontal axis and the vertical axis refer to the x or y axis in the horizontal plane when other technicians model themselves using software.

[0021] The slotted mushroom-shaped AMC array is used for shielding electromagnetic radiation in a wide frequency band, and is suitable for a frequency range of 13.55MHz-15.55MHz. Thus, the problem that the prior art can only have good shielding effect in a specific frequency range is solved.

[0022] The thickness of the dielectric substrate of the intermediate dielectric layer is in the range of 3mm to 5mm within the applicable frequency. By equivalent the AMC array to a perfect magnetic conductor (PMC) at the resonant frequency, the leakage of the electromagnetic field is effectively suppressed, and the shielding effect is improved.

[0023] The shielding electromagnetic metamaterial is used in a magnetic coupling resonant wireless energy transmission (MCR-WPT) system, the slotted mushroom-shaped AMC units are arranged in an array, and the metal surface formed by the corresponding combination of the top patch and the bottom patch has high impedance characteristics, can be equivalent to a perfect magnetic conductor (PMC) at the resonant frequency, effectively suppresses the leakage of the electromagnetic field, and is applied to a MCR-WPT wireless energy transmission system.

[0024] The slotted mushroom-shaped AMC array is used as a shielding plate in the MCR-WPT system, and the distance between the shielding plate and the coil in the MCR-WPT is in the range of 30mm to 100mm to achieve the best electromagnetic shielding effect.

[0025] The top layer patch and the bottom layer patch in the slotted mushroom type AMC array are metal patches, the metal patch is square, circular or rectangular in shape, the spacing between the top layer patches between adjacent units ranges from 2mm to 20mm, and the bottom layer patches between adjacent units can be directly connected. Thus, the shielding effect and working efficiency of the AMC array are further improved.

[0026] Within the applicable frequency range, the side length of the slotted mushroom type AMC unit patch ranges from 240mm to 420mm, and the slot gap length of the slotted slot ranges from 50mm to 130mm, which can improve the system transmission efficiency and stability.

[0027] The slotted mushroom type AMC array adopts a mushroom type structure with a central metal through hole, and the diameter of the metal through hole ranges from 6mm to 14mm within the applicable frequency range, which can effectively regulate and shield the spatial magnetic field distribution around the resonance coil and reduce electromagnetic interference.

[0028] The surface slotted slot is U-shaped.

[0029] The beneficial effects of the present application are:

[0030] (1) When electromagnetic waves are incident on the shielding metamaterial based on the mushroom type AMC slotted structure of the present application, the metamaterial produces electromagnetic response, and then exhibits the characteristics of an equivalent perfect magnetic conductor (PMC) at the working frequency of the electromagnetic wave. By controlling the unit length of the top layer and the bottom layer patch, the length and width of the top layer patch slotted, the thickness and material of the central metal through hole of the bottom layer patch, the equivalent inductance and slot capacitance of the mushroom type AMC slotted unit are realized, and then the working frequency of the shielding metamaterial is adjusted, and the miniaturization design is completed.

[0031] (2) The shielding metamaterial based on the mushroom type AMC slotted structure provided by the present application can be equivalent to a perfect magnetic conductor (PMC) at the working frequency of the wireless power transmission system, and can be used to shield the electromagnetic leakage of the wireless power transmission system, weaken the harm of electromagnetic radiation to surrounding equipment and humans, and allow the magnetic field of other frequency bands to pass without interference. The frequency shielded in the present application is 13.553MHz-13.567MHz frequency and 13.56MHz-15.55MHz in the ISM (Industrial Scientific Medical) frequency band, which is widely used in the fields of industry, science and medicine. The shielding metamaterial does not affect the normal operation of other devices, and thus is conducive to accelerating the industrialization application of metamaterials.

[0032] (3) The mushroom type AMC open slot structure based shielding metamaterial provided by the application has the advantages of light mass, thin thickness, small volume and small energy loss, and the mushroom type AMC open slot structure based shielding metamaterial of the design can adjust equivalent inductance and slot capacitance by changing the structure, obtain the required frequency, and is convenient to operate.

[0033] (4) The mushroom type AMC open slot unit is combined with the top patch, the bottom patch and the middle medium layer, and the AMC array shielding metamaterial is obtained through the optimization design.

[0034] In conclusion, the application solves the technical defects of the prior art, such as large volume, high cost, poor shielding effect, generation of additional electromagnetic radiation and large loss, complex structure design and reduction of transmission efficiency of a wireless energy transmission system, and provides a new artificial magnetic conductor (AMC) electromagnetic metamaterial, which can realize magnetic field shielding and high-efficiency energy transmission of a wireless energy transmission system. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 HFSS unit diagram of the mushroom type AMC open slot structure.

[0036] Figure 2 Four-coil MCR-WPT system HFSS model simplified comparison diagram of the AMC array.

[0037] Figure 3 HFSS infinite periodic unit full-wave simulation boundary condition setting diagram.

[0038] Figure 4 Mushroom type AMC open slot unit reflection phase HFSS simulation curve diagram.

[0039] Figure 5 Designed four-coil MCR-WPT system HFSS model diagram.

[0040] Figure 6 Four-coil MCR-WPT system HFSS simulation magnetic field distribution diagram.

[0041] Figure 7 3x3 AMC array and four-coil MCR-WPT system HFSS model diagram of the AMC array.

[0042] Figure 8 Four-coil MCR-WPT system HFSS simulation magnetic field distribution diagram of the AMC array.

[0043] Figure 9The AMC array surface current vector diagram for loading in the four-coil MCR-WPT system.

[0044] Figure 10 The magnetic field strength comparison diagram of the four-coil MCR-WPT system before and after loading the AMC array.

[0045] Figure 11 The transmission efficiency curve diagram of the four-coil MCR-WPT system when D=550mm and D changes.

[0046] Figure 12 The efficiency change curve diagram of the four-coil MCR-WPT system when wl changes.

[0047] Figure 13 The efficiency change curve diagram of the four-coil MCR-WPT system when sl changes.

[0048] Figure 14 The efficiency change curve diagram of the four-coil MCR-WPT system when d changes.

[0049] Figure 15 The overall structure diagram of the slotted mushroom-shaped AMC unit. DETAILED DESCRIPTION

[0050] The application will be further described in detail below with reference to the accompanying drawings.

[0051] As shown in Figure 1 , Figure 15 , a shielding electromagnetic metamaterial based on a slotted mushroom-shaped AMC structure, the slotted mushroom-shaped AMC unit structure with shielding effect is designed based on the equivalent circuit theory.

[0052] The in-phase reflection phase characteristics of the slotted mushroom-shaped AMC are analyzed from the perspective of equivalent circuit. As shown in reference Figure 15 , the slotted mushroom-shaped AMC structure is composed of three layers, which are periodic metal top patch, dielectric substrate (middle dielectric layer) and metal ground plate (bottom patch), and a metal material through hole is arranged at the center position to connect the top patch and the bottom patch.

[0053] It is assumed that the electromagnetic wave is vertically incident to the top patch of the slotted mushroom-shaped AMC unit surface, and the main function of the metal through hole is to flow the current generated by the electromagnetic wave radiation to the metal ground plate, thereby forming an equivalent inductor L.

[0054] In order to simplify the design and adjust the structure resonance frequency, therefore, the application adopts the slotted method to realize the design of removing the external capacitor device and also presenting the capacitive and having the shielding effect, that is, the slotted slot of the patch unit at the slot position forms a slot capacitor C.

[0055] According to the equivalent circuit theory, if the resonant frequency is f, the surface impedance and the resonant frequency point of the structure are respectively:

[0056]

[0057] Then determine any three structure parameters of the slotted mushroom type AMC unit, according to the relationship between the slotted mushroom type AMC structure parameters and the gap capacitance C and the equivalent inductance L, the remaining one structure parameter can be determined:

[0058]

[0059] L = μ0h

[0060] In the formula, ε0 and μ0 are the vacuum permittivity and vacuum permeability respectively, the dielectric constant of the dielectric substrate is μ r , the thickness is h, the patch unit side length is Wl, the gap length is sl, the gap width is sw, and the unit spacing is gl. From the above formula, when the slotted mushroom type AMC structure is incident by electromagnetic wave with resonant frequency f, the surface impedance is infinite, at this time the surface of the slotted mushroom type AMC structure can be approximated as an ideal magnetic surface (PMC).

[0061] The slotted mushroom type AMC unit structure is parameterized modeling, and the unit performance is optimized.

[0062] It can be known from the slotted mushroom type AMC resonant frequency point formula obtained by using the equivalent circuit analysis method that the main parameters affecting the slotted mushroom type AMC resonant frequency point are the gap capacitance and the equivalent inductance, that is, the in-phase reflection phase performance of the slotted mushroom type AMC structure is only affected by the topological structure of the structure and the size of the structure.

[0063] Referring to Figure 1 , Figure 15 The slotted mushroom type AMC structure unit diagram is shown. The dielectric constant ε r and the loss tangent tanσ of the dielectric substrate of the middle dielectric layer are shown, the thickness h, the via diameter r, the unit side length wl, the gap length sl, the unit spacing gl, the gap width sw, and the patch thickness t are shown. Except for the slotted size of the top patch, the structure parameters of the top patch and the bottom patch are consistent.

[0064] The parameterized unit is optimized, and the parameters are optimized with the given in-phase reflection phase as the target, that is, the structure needs to be in the bandwidth range centered on the target resonance frequency, and the reflection phase change range reaches 180°, so that the most suitable parameters of the structure at the target frequency can be obtained. Because when the electromagnetic wave is incident on the upper surface of the slotted mushroom-shaped AMC unit, if a 180° phase shift is generated in the transmission process of the wave, it is a same-direction reflection. Then the phase shift generated in the transmission process and the phase shift generated by the reflection of the AMC unit can be superimposed, and then a same-phase superposition effect can be generated in the direction of the coil, thereby enhancing the magnetic field between the coils and improving the transmission efficiency between the coils.

[0065] The AMC array uses a slot coupling capacitor instead of an external lumped capacitor, adjusts the operating frequency, realizes miniaturization, reduces design complexity and processing difficulty, and improves shielding effect and operating efficiency by optimizing structural parameters such as size Wl, shape (square or circular arc), and spacing gl of the metal patch. The influence of the side length of the AMC unit and the slot length on the transmission efficiency of the wireless energy transmission system is analyzed by using the HFSS software, and the distance between the shielding plate and the coil is reasonably set to achieve the best electromagnetic shielding effect. The AMC array has the characteristics of high-efficiency wide-band shielding performance, low cost and strong adaptability in practical application, and is suitable for various working environments and needs.

[0066] Application of shielding electromagnetic metamaterial based on slotted mushroom-shaped AMC structure.

[0067] Mushroom-shaped AMC slotted unit forms an AMC array and is applied to an MCR-WPT energy transmission system.

[0068] The mushroom-shaped AMC slotted unit forms an m x m AMC array and is loaded into the MCR-WPT system. The AMC array is placed horizontally at a distance d from the coil, and the transmission distance D.

[0069] The positions of the four-coil system and the AMC array are shown in Figure 2 , and the reference Figure 2 is A simplified comparison chart of the HFSS model of the four-coil MCR-WPT system loaded with the AMC array. The four-coil MCR-WPT system consists of a single-turn excitation coil, a multi-turn transmitting resonant coil, a multi-turn receiving resonant coil, and a single-turn load coil. The distance between the AMC array and the coil is d1 = d2 = d, and L1 and L2 are the observation planes located above and below the receiving coil, respectively.

[0070] Example 1:

[0071] The technical parameters used in the simulation are: the dielectric constant of the mushroom-shaped AMC slotted unit is ε rFR4 material with a resonance frequency of =4.4 and a loss tangent of tanσ=0.02, a thickness of h=3mm, a via diameter of r=10mm; a unit side length of wl=320mm, a slot side length of sl=130mm, a unit spacing of gl=14mm, a slot width of sw=10mm, a patch thickness of t=0.035mm, and the top layer having the same structure parameters as the bottom layer except for the top layer slot size. The four-coil MCR-WPT system designed in the application has a working frequency of 13.9MHz, is composed of a single-turn excitation coil and a load coil and a n=5-turn transmitting resonant coil and a receiving resonant coil, has an outer side length of the transmitting and receiving resonant coils of a=260mm, an outer side length of the excitation and load coils of b=186mm, and a matching circuit of the excitation and load coils using a combination of a parallel H=105nH inductor and a series F=250pF capacitor. The mushroom-shaped AMC slot unit is arranged in a 3x3 AMC array, is loaded into the MCR-WPT system, and is horizontally placed at a distance of d=50mm from the coils, and has a transmission distance of D=550mm.

[0072] The reflection phase of the unit structure is calculated by using a three-dimensional simulation software HFSS, and the simulation curve of the reflection phase of the slot mushroom-shaped AMC unit is shown in Figure 3 A boundary condition setting diagram for full-wave simulation of the infinite periodic unit is shown. A Floquet port is used for excitation, wherein the port is greater than a quarter of the wavelength corresponding to the calculation frequency from the surface of the slot mushroom-shaped AMC unit, and a Master / Slave boundary condition is used. Figure 4 The simulation curve of the reflection phase of the slot mushroom-shaped AMC unit is shown in Figure 4 It can be seen from

[0073] The HFSS model diagram of the designed four-coil MCR-WPT system is shown in Figure 5 The magnetic field distribution of the four-coil MCR-WPT system is simulated by using HFSS, and the transmission efficiency of the four-coil MCR-WPT system corresponding to different transmission distances is obtained. The transmission efficiency of the four-coil MCR-WPT system corresponding to different transmission distances is shown in Figure 6 The magnetic field distribution of the four-coil MCR-WPT system is simulated by using HFSS, and the transmission efficiency of the four-coil MCR-WPT system corresponding to different transmission distances is obtained. The transmission efficiency of the four-coil MCR-WPT system corresponding to different transmission distances is shown in

[0074] The HFSS model diagram of the designed four-coil MCR-WPT system is shown in Figure 7This is a model diagram of a 3×3 AMC array and a four-coil MCR-WPT system with the AMC array loaded. The AMC array is placed horizontally at a distance of d = 50 mm from the coil, and the transmission distance is D = 550 mm. The four-coil system is maintained... Figure 5 The coil structure parameters remain unchanged, where the distance between the AMC array and the coil is d1 = d2 = d, and L1 and L2 are the observation surfaces placed above and below the receiving coil, respectively. HFSS simulation was performed to obtain the HFSS simulated magnetic field distribution of the four-coil MCR-WPT system with the AMC array loaded. Figure 8 .

[0075] Depend on Figure 6 and Figure 8 It can be concluded that without the AMC array, there is a significant magnetic field leakage around the resonant coil. However, when the AMC array is added as a shielding material, the leakage magnetic field is effectively suppressed, indicating that the AMC array has a good shielding effect. When the AMC array is placed below the helical coil as a shielding material, the high-frequency alternating current in the coil excites an alternating electromagnetic field, which interacts with the AMC array, thereby generating eddy currents in the AMC array. The eddy current vector diagram is shown in the reference diagram. Figure 9 Eddy currents are mainly distributed in a ring-shaped region and flow in the opposite direction to the coil current, thereby generating a reverse magnetic field that weakens the original magnetic field and achieves a shielding effect.

[0076] Combination Figure 6 , Figure 8 and Figure 9 Without an AMC array, there is significant magnetic field leakage around the resonant coil. However, when an AMC array is added as a shielding material, the leakage magnetic field is effectively suppressed, indicating that the AMC array has a good shielding effect. When the AMC array is placed below the helical coil as a shielding material, the high-frequency alternating current in the coil excites an alternating electromagnetic field, which interacts with the AMC array to form an induced electromotive force, thereby generating eddy currents in the AMC array. The eddy current vector diagram is shown below. Figure 9 .

[0077] Then Figure 8 The magnetic field strength at the observation surfaces L1 and L2 is similar to Figure 6 The magnetic field strength at the corresponding locations was analyzed to obtain a comparison of the magnetic field strength of the four-coil MCR-WPT system before and after the AMC array was applied. Figure 10 .Depend on Figure 10It can be seen that after loading the AMC array, the back-radiated magnetic field strength of the coil decreased from 3.05 A / m to 0.173 A / m; after loading the AMC array, the peak magnetic field strength in the transmission path of the receiving coil increased from 2.09 A / m to 4.36 A / m. Because each mushroom-shaped AMC slotted unit can be equivalent to an LC circuit, the periodically arranged AMC array units are coupled to each other. When excited by the magnetic field of the coil, the coupling mode of the AMC will be activated and resonate with the coil. At this time, more magnetic field energy will be absorbed by the receiving coil, improving the transmission efficiency of the system. In this specific embodiment, the AMC array can generate reverse eddy currents at 13.56MHz, 13.9MHz, 15.35MHz, 15.4MHz, and 15.55MHz, achieving a shielding effect. It can also resonate with the coil and significantly improve the overall efficiency and transmission distance of the wireless power transmission system, making it suitable for different types of wireless power transmission, including but not limited to the MCR-WPT system.

[0078] Example 2:

[0079] The technical parameters used in the simulation are as follows: the dielectric substrate of the mushroom-shaped AMC slotted cell is selected with a dielectric constant ε. r The FR4 material has a loss tangent of tanσ = 0.02 and a thickness of h = 3 mm. The through-hole diameter is r = 10 mm. The unit side length is wl = 240 mm, the gap side length is sl = 130 mm, the unit spacing is gl = 14 mm, the gap width is sw = 10 mm, and the patch thickness is t = 0.035 mm. Except for the top layer slot size, the top and bottom layer structural parameters are the same. The four-coil MCR-WPT system designed in this invention operates at a frequency of 13.9 MHz. It consists of a single-turn excitation coil and a load coil, and n = 5 turns of transmitting resonant coil and receiving resonant coil. The outer side length of the transmitting and receiving resonant coils is a = 260 mm, and the outer side length of the excitation and load coils is b = 186 mm. The matching circuit of the excitation and load coils adopts a combination of first connecting an H = 105 nH inductor in parallel and then connecting a F = 250 pF capacitor in series. A 4×4 AMC array is formed by assembling mushroom-shaped AMC slotted units and loaded into the MCR-WPT system. The AMC array is placed horizontally at a distance d = 50 mm from the coil, with a transmission distance D = 550 mm. In this specific embodiment, the AMC array can generate reverse eddy currents at 13.56 MHz, 13.9 MHz, 15.35 MHz, 15.4 MHz, and 15.55 MHz, achieving a shielding effect. It can also resonate with the coil, significantly improving the overall efficiency and transmission distance of the wireless power transfer system. It is suitable for different types of wireless power transfer, including but not limited to the MCR-WPT system.

[0080] Example 3:

[0081] The technical parameters used in the simulation are as follows: the dielectric substrate of the mushroom-shaped AMC slotted cell is selected with a dielectric constant ε. r The FR4 material has a loss tangent of tanσ = 0.02 and a thickness of h = 3 mm. The through-hole diameter is r = 10 mm. The unit side length is wl = 320 mm, the gap side length is sl = 50 mm, the unit spacing is gl = 14 mm, the gap width is sw = 10 mm, and the patch thickness is t = 0.035 mm. Except for the top layer slot size, the top and bottom layer have the same structural parameters. The four-coil MCR-WPT system designed in this invention operates at a frequency of 13.9 MHz. It consists of a single-turn excitation coil and a load coil, and n = 5 turns of transmitting resonant coil and receiving resonant coil. The outer side length of the transmitting and receiving resonant coils is a = 260 mm, and the outer side length of the excitation and load coils is b = 186 mm. The matching circuit of the excitation and load coils uses a combination of first connecting an H = 105 nH inductor in parallel and then connecting a F = 250 pF capacitor in series. A 3×3 AMC array is formed by assembling mushroom-shaped AMC slotted units and loaded into the MCR-WPT system. The AMC array is placed horizontally at a distance of d = 50 mm from the coil, with a transmission distance of D = 550 mm. In this specific embodiment, the AMC array can generate reverse eddy currents at 13.56 MHz, 13.9 MHz, 15.35 MHz, 15.4 MHz, and 15.55 MHz, achieving a shielding effect. It can also resonate with the coil, significantly improving the overall efficiency and transmission distance of the wireless power transmission system. It is suitable for different types of wireless power transmission, including but not limited to the MCR-WPT system.

[0082] Example 4:

[0083] The technical parameters used in the simulation are as follows: the dielectric substrate of the mushroom-shaped AMC slotted cell is selected with a dielectric constant ε. rFR4 material with a thickness h = 3 mm, a via diameter r = 10 mm, a unit length wl = 320 mm, a gap length sl = 130 mm, a unit spacing gl = 14 mm, a gap width sw = 10 mm, and a patch thickness t = 0.035 mm, except that the top layer has a slotted size, and the top layer and the bottom layer have consistent structure parameters. It is verified that the working frequency of the four-coil MCR-WPT system designed in the application is 13.9 MHz, which is composed of a single-turn excitation coil and a load coil and a n = 5-turn transmitting resonant coil and a receiving resonant coil, the outer length of the transmitting and receiving resonant coils a = 260 mm, the outer length of the excitation and load coils b = 186 mm, and the matching circuit of the excitation and load coils adopts a combination of a parallel H = 105 nH inductor and a series capacitor F = 250 pF. The 3x3 AMC array composed of the mushroom-shaped AMC slotted units is loaded into the MCR-WPT system, and the AMC array is horizontally placed at a distance d = 100 mm from the coil, and the transmission distance D = 550 mm. The AMC array in the specific embodiment can form a reverse eddy current at 13.56 MHz, 13.9 MHz, 15.35 MHz, 15.4 MHz, and 15.55 MHz, achieve a shielding effect, and can resonate with the coil and significantly improve the overall efficiency and transmission distance of the wireless energy transmission system, and is suitable for different types of wireless energy transmission including but not limited to the MCR-WPT system.

[0084] Embodiment 5:

[0085] In this embodiment, the unit length wl and the gap length sl of the mushroom-shaped AMC slotted unit in Embodiments 2-4 are changed, and the performance simulation test of the AMC array placed at a distance d from the coil and the transmission distance D of the system is performed.

[0086] The other structure parameters of the AMC array are kept unchanged, D is taken from 550 mm to 1575 mm, and the transmission efficiency curve of the four-coil MCR-WPT system when D = 550 mm and D changes is obtained Figure 11 . It can be obtained that Figure 11 when D = 550 mm, the transmission efficiency of the four-coil MCR-WPT after loading the AMC array is improved from 17% to 93%; and when the transmission distance is 1050 mm, the transmission efficiency of the system is 83%, and when the transmission distance is 1575 mm, the transmission efficiency of the system is 40%, compared with the four-coil system without loading the AMC array, the overall efficiency and transmission distance are significantly improved.

[0087] The other structure parameters of the AMC array are kept unchanged, wl is taken from 240 mm to 400 mm, and the overall simulation of the four-coil MCR-WPT system loaded with the AMC array is performed, and the efficiency change curve of the four-coil MCR-WPT system when wl changes is obtained Figure 12By Figure 12 It can be concluded that when the unit side length wl gradually increases, the transmission efficiency of the system also gradually rises, and different optimal distances wl need to be found for different wireless energy transmission systems.

[0088] Keeping other structural parameters of the AMC array unchanged, taking sl as 50mm, 60mm, 70mm, the overall simulation of the four-coil MCR-WPT system loaded with the AMC array is carried out, and the efficiency curve of the four-coil MCR-WPT system is obtained when sl changes Figure 13 By Figure 13 It can be concluded that when the slot side length sl increases, the working frequency of the system will shift to high frequency, and we can adjust the working frequency of the system by adjusting the size of sl, and different optimal sl values need to be found for different wireless energy transmission systems.

[0089] Keeping other structural parameters of the AMC array unchanged, taking the AMC array placed at a distance d of 30mm-100mm from the coil, the overall simulation of the four-coil MCR-WPT system loaded with the AMC array is carried out, and the efficiency curve of the four-coil MCR-WPT system is obtained when d changes Figure 14 By Figure 14 It can be concluded that the distance between the AMC array and the coil will affect the coupling of the system, and different optimal distances d need to be found for different wireless energy transmission systems.

[0090] Embodiment 6:

[0091] Suppose the current resonant frequency is f, and the structural parameters required by the structure are designed according to the given steps 1-3, if the frequency of the incident electromagnetic wave is f0, then the resonant frequency f needs to be changed to f0 to achieve the shielding effect. But you don't need to redesign the structure according to steps 1-3, you only need to change the appropriate slot length sl, and the resonant frequency of this structure can be changed to the frequency f0 of the incident electromagnetic wave, greatly reducing the design complexity, and also saving the cost of redesign. For example Figure 13 The working frequency of the system can be adjusted by adjusting the size of sl, and for different wireless energy transmission systems, sl can be directly changed to meet the demand.

[0092] For the problem of large volume, the application adopts micro-structured material composed of metal patch and dielectric substrate, so that the shielding device is suitable for miniaturization and integration application; for the problem of high manufacturing cost, through the design of unit structure, the unit surface gap coupled capacitance is used instead of lumped capacitance, so as to reduce the production cost; for the problem of large loss, the electromagnetic metamaterial designed by the application can greatly reduce the electromagnetic energy dissipation in unnecessary areas, so as to improve the transmission efficiency of the system; for the problem of complex design, through the innovative structure design of slotted mushroom, the manufacturing and debugging process is simplified; for the problem of additional electromagnetic radiation, the material of the application hardly produces additional scattering radiation in the shielding process, so as to improve the safety and environmental protection of the system. These improvements significantly solve the deficiencies in the prior art, and improve the performance and application prospect of the wireless energy transmission system.

[0093] The application solves the technical defects of the electromagnetic shielding material in the prior art, such as large volume, high cost, poor shielding effect, generation of additional electromagnetic radiation, large loss, complex structure design and reduction of transmission efficiency of the wireless energy transmission system, and provides a new artificial magnetic conductor (AMC) electromagnetic metamaterial, which can realize magnetic field shielding and high-efficiency energy transmission for the wireless energy transmission system.

[0094] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the application, and is not intended to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A shielded electromagnetic metamaterial based on a split mushroom type AMC structure, characterized in that, The shielding electromagnetic metamaterial is an m x m array composed of slit mushroom-shaped AMC units, the slit mushroom-shaped AMC unit comprises, from top to bottom, a top patch, an intermediate dielectric layer, and a bottom patch; The center of the top patch is connected to the center of the bottom patch through a metal through hole penetrating through the intermediate dielectric layer; the top patch has a surface slit, and the top patch is arranged on the front surface of the intermediate dielectric layer; the bottom patch is arranged on the back surface of the dielectric layer; When an electromagnetic wave is vertically incident on the top patch, a current is generated and flows to the bottom patch, forming an equivalent inductance L, and a slit capacitor C is formed in the surface slit of the top patch; According to the equivalent circuit theory, if the resonance frequency is f, the surface impedance of the structure and the resonance frequency point are respectively: Determine any three structural parameters of the slit mushroom-shaped AMC unit, and determine the remaining one structural parameter according to the relationship between the slit mushroom-shaped AMC structural parameters and the slit capacitor C and the equivalent inductance L: where ε0and μ0are the vacuum permittivity and permeability, respectively, the dielectric constant of the intermediate dielectric layer is ε r , the thickness is h, the patch cell side length of the top layer patch and the bottom layer patch is Wl, the square slot side length is sl, the slot width is sw, and the cell spacing is gl.

2. The shielding electromagnetic metamaterial based on slotted mushroom-type AMC structure according to claim 1, characterized in that, The slit coupling capacitor formed by the slit groove structure of the top patch replaces the lumped capacitor, the slit width sw ranges from 8 mm to 12 mm, the shape of the slit is square or circular, and the metal through hole connects the top patch to form a mushroom shape; The top patch of the slit groove is symmetrical about the horizontal axis or the vertical axis.

3. The shielding electromagnetic metamaterial based on slotted mushroom-type AMC structure according to claim 1, characterized in that, The slit mushroom-shaped AMC array is used for shielding electromagnetic radiation in a wide frequency band, and is suitable for a frequency range of 13.55 MHz-15.55 MHz.

4. The shielding electromagnetic metamaterial based on slotted mushroom-type AMC structure according to claim 3, characterized in that, The thickness of the dielectric substrate of the intermediate dielectric layer ranges from 3 mm to 5 mm within the applicable frequency range.

5. The electromagnetic shielding metamaterial according to any one of claims 1-4, applied to a wireless power transfer system such as MCR-WPT, characterized in that, The slit mushroom-shaped AMC units are arranged in an array, and the metal surface formed by the corresponding combination of the top patch and the bottom patch makes the array have high impedance characteristics, can be equivalent to a perfect magnetic conductor (PMC) at the resonance frequency, effectively suppresses the leakage of the electromagnetic field, and is applied to a wireless energy transmission system such as MCR-WPT.

6. The electromagnetic shielding metamaterial of claim 5, applied to a wireless power transfer system such as MCR-WPT, characterized in that, The slit mushroom-shaped AMC array is applied to the MCR-WPT system as a shielding plate, and the distance between the shielding plate and the coil ranges from 30 mm to 100 mm.

7. The electromagnetic shielding metamaterial according to claim 6, applied to a wireless power transfer system such as MCR-WPT, characterized in that, In the slit mushroom-shaped AMC array, the top patch and the bottom patch are metal patches, the metal patch has a square, circular or rectangular shape, the distance between the top patches of adjacent units ranges from 2 mm to 20 mm, and the bottom patches of adjacent units are directly connected.

8. The electromagnetic shielding metamaterial of claim 6, applied to a wireless power transfer system such as MCR-WPT, characterized in that, Within the applicable frequency range, the side length of the slit mushroom-shaped AMC patch unit ranges from 240 mm to 420 mm, and the slit length of the slit groove ranges from 50 mm to 130 mm; The diameter of the metal through hole ranges from 6 mm to 14 mm within the applicable frequency range, which can effectively control and shield the spatial magnetic field distribution around the resonance coil and reduce electromagnetic interference; The surface slit is U-shaped.

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