CN115966886A - Very-low-frequency multilayer magnetoelectric mechanical antenna and preparation method thereof - Google Patents

Abstract

The invention provides a very-low-frequency multilayer magnetoelectric mechanical antenna and a preparation method thereof, belonging to the technical field of low-frequency antennas. The electromagnetic antenna solves the prominent problems of small power capacity, weak radiation capability and short communication distance of the conventional magnetoelectric mechanical antenna. The multilayer magnetic memory comprises a plurality of laminated magnetic layers and a plurality of piezoelectric layers, wherein the plurality of laminated magnetic layers and the plurality of piezoelectric layers are alternately stacked to form electrical parallel connection and mechanical parallel connection. Compared with the traditional magnetic material structure, the multilayer magnetoelectric mechanical antenna has the advantages that the volume is increased, and the saturation magnetic moment of a system is enhanced; meanwhile, the system load is increased by the multiple piezomagnetic layers, the mechanical quality factor of the magnetoelectric mechanical antenna can be effectively reduced, and the nonlinear behavior of the oscillator under a strong field is inhibited. Under the same driving condition, the power capacity and the radiation field strength of the oscillator can be increased, the radiation field strength reaches 87fT in 100m free space, and the modulation rate reaches 500Hz at most.

Description

A very low frequency multi-layer magneto-electric mechanical antenna and its preparation method

technical field

The invention belongs to the technical field of low-frequency antennas, in particular to a very low-frequency multilayer magnetoelectric mechanical antenna and a preparation method thereof.

Background technique

How to solve communication problems in extreme environments, such as cross-ground communication, underwater communication and external communication of human implanted devices is a key problem that needs to be solved urgently. The current common radio frequency antenna transmits information through electromagnetic waves generated by high-frequency currents, but its size must be comparable to the wavelength of the radiated electromagnetic waves, which cannot meet the needs of miniaturization and high efficiency at the same time.

In order to solve the above problems, DARPA (Defense Advanced Research Projects Agency) of the United States launched a mechanical antenna research project (A MEchanically Based Antenna, No.: HR001117S0007) in 2017, aiming to improve and develop low-frequency, low-power consumption. , Miniaturized magnetic field transmitting antenna. Compared with traditional antenna forms, mechanical antennas create time-varying electromagnetic fields in space by driving electric dipoles or magnetic dipoles. Since the mechanical antenna directly converts mechanical energy into electromagnetic field energy, avoiding the way of high-frequency oscillating current radiation, it does not need to be limited by the physical size of traditional antennas, and the information (modulation) bandwidth can be independent of the physical (loss) bandwidth. Among the mechanical antennas, the magnetoelectric mechanical antenna using the magnetoelectric coupling effect as the working principle is one of the key solutions for the development of cross-media communication technology.

In order to obtain magnetoelectric mechanical antennas with strong radiation capabilities, domestic and foreign scholars have done a lot of research work. In 2017, Nan Tianxiang, Sun Nianxiang and others from Northeastern University in the United States first experimentally reported the NEMS mechanical antenna based on the magnetoelectric multiferroic heterojunction FeGaB/AlN, which solved the design problem of traditional antenna miniaturization. Recently, the research group of Professor Nianxiang Sun from Northeastern University further used 2-1 type magnetoelectric composite materials to build a very low frequency magnetic field communication system. Under the power consumption of 400mW, the transmission distance of 120m and the modulation bandwidth of 100Hz were realized.

However, the current common 1-1 type, 2-1 type and other magneto-electric mechanical antennas have low radiation capability and power capacity, and at the same time, the mechanical quality factor (Q value) is also high. For antenna radiation, this means that most of the energy is stored inside or on the surface of the antenna, but is not effectively radiated to the free space outside, resulting in low radiation efficiency and short communication distance. In addition, the Q value is inversely proportional to the antenna bandwidth, and a high Q value means that the bandwidth of the antenna itself is narrow, resulting in a relatively low communication rate. Although the traditional 2-1 magnetoelectric antenna working in the multi-push-pull mode has strong resonant magnetoelectric coupling characteristics, the total saturation magnetic moment of the system is not strong due to the relatively small volume of the piezoelectric layer. Although the 1-1 type magnetoelectric antenna has high resonant coupling performance in the first-order vibration mode, its Q value is high, it is prone to nonlinear behavior, and it is difficult to support high electric field driving. Both of the above two magneto-electric mechanical antenna structures cannot meet the application requirements of transmitting high-intensity electromagnetic field signals.

Contents of the invention

In view of this, the present invention aims to propose a very low frequency multi-layer magneto-electric mechanical antenna and its preparation method to solve the outstanding problems of low power capacity, weak radiation ability and short communication distance commonly existing in existing magneto-electric mechanical antennas. It can be applied to scenarios such as cross-media communication and sensing.

In order to achieve the above object, the present invention adopts the following technical solutions: a very low frequency multilayer magnetoelectric mechanical antenna, including multilayer piezoelectric layers and multilayer piezoelectric layers. The multilayer piezoelectric layers and the multilayer piezoelectric layers are alternately stacked to form an electrical parallel connection.

Furthermore, the piezoelectric magnetic layer is composed of a soft magnetic block or a multilayer composite of a soft magnetic tape, wherein the soft magnetic material is Metglas, Fe-Ga alloy, Terfernol-D alloy, Fe-Ni alloy, FeCo, FeCoB , FeGaB, NiZn ferrite and one of Ni metal, connected by epoxy resin.

Furthermore, the piezoelectric material of the piezoelectric layer includes piezoelectric ceramics and piezoelectric single crystals, and the piezoelectric materials are LiNbO ₃ , BaTiO ₃ , Pb(Zr,Ti)O ₃ , Pb(Mg,Nb)O ₃ - one of PbTiO ₃ , Pb(Zn,Nb)O ₃ -PbTiO ₃ or BiScO ₃ -PbTiO ₃ .

Furthermore, the piezoelectric layer and the piezoelectric layer are connected by epoxy resin.

Furthermore, each piezoelectric layer is polarized along the thickness direction, and is electrically connected in parallel, and the antenna works in the d31 mode at this time.

Furthermore, the piezoelectric layer can also be made of macroscopic piezoelectric fiber composite material (Marco Fiber Composite, MFC), adopting the longitudinal polarization method, forming a sandwich structure with the upper and lower piezoelectric layer electrodes, and the three-layer structure is compounded by epoxy resin. At this time, the antenna works in d33 mode.

A method for preparing a multilayer magneto-electric mechanical antenna in a longitudinal vibration mode, specifically comprising the following steps:

(1) Antenna structure design and simulation verification;

(2), material processing, packing box preparation;

(3), preparation of piezoelectric layer;

(4), preparation of the piezoelectric layer;

(5), bonding and compounding the piezoelectric layer and the piezoelectric layer;

(6) Paste the piezoelectric layer electrodes on the corresponding piezoelectric layer to obtain the final prototype of the multilayer mechanical antenna.

Compared with the prior art, the innovations and beneficial effects of the multilayer magneto-electric mechanical antenna with longitudinal vibration mode and its preparation method according to the present invention are:

The multilayer magnetoelectric mechanical antenna described in the present invention increases the saturation magnetic moment of the system compared with the increase in the volume of the traditional magnetic material; meanwhile, the multilayer laminated magnetic layer increases the system load, which can effectively reduce the magnetoelectric mechanical antenna. The mechanical quality factor of the vibrator suppresses the nonlinear behavior of the vibrator under a strong field. Under the same driving conditions, the power capacity and radiation field strength of the vibrator can be increased, and the radiation field strength can reach 87fT in a 100m free space, and the modulation rate can reach up to 500Hz.

Description of drawings

The drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 is the size schematic diagram of the multilayer magnetoelectric mechanical antenna of the present invention;

Fig. 2 is a structural schematic diagram of a specific embodiment 1 of a multilayer magneto-electric mechanical antenna according to the present invention;

Fig. 3 is the simulation result figure of the COMSOL of specific embodiment one among the present invention, comprises first-order longitudinal vibration mode and characteristic frequency thereof;

Fig. 4 is a graph showing the relationship between radiation performance and distance in Embodiment 1 of the multilayer magnetoelectric mechanical antenna according to the present invention;

Fig. 5 is the relationship between the resonant frequency and the driving field strength in Embodiment 1 of the multi-layer magneto-electric mechanical antenna according to the present invention;

Fig. 6 is a schematic structural diagram of a second embodiment of the multilayer magneto-electric mechanical antenna according to the present invention;

FIG. 7 is a schematic structural diagram of a third embodiment of the multilayer magneto-electric mechanical antenna according to the present invention;

In the figure: 1-piezoelectric layer electrode, 2-piezoelectric layer, 3-piezomagnetic layer.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be noted that, in the case of no conflict, the embodiments and the features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments.

This embodiment will be described with reference to FIGS. 1-7. A multilayer magnetoelectric mechanical antenna in longitudinal vibration mode, including four piezoelectric layers 3 and three piezoelectric layers 2. The piezoelectric layers 3 and the piezoelectric layers 2 are alternately stacked with epoxy resin, and the piezoelectric layers are electrically and mechanically connected in parallel.

Each laminated magnetic layer 3 is 100 mm long, 2 mm wide, and 0.25 mm thick; each piezoelectric layer 2 is 70 mm long, 1.5 mm wide, and 0.48 mm thick; each piezoelectric layer electrode 1 is 0.05 mm thick, and the piezoelectric layer electrode 1 using copper material. According to specific embodiments, the shape and size of the soft magnetic layer 3 can also be changed accordingly

The pressure magnetic layer 3 is made of a soft magnetic block material or a multilayer composite of a soft magnetic tape material, wherein the soft magnetic material is Metglas, Fe-Ga alloy, Terfernol-D alloy, Fe-Ni alloy, FeCo, FeCoB, FeGaB, One of NiZn ferrite and Ni metal, connected by epoxy resin.

The piezoelectric material of the piezoelectric layer 2 includes piezoelectric ceramics and piezoelectric single crystal, and the piezoelectric material is LiNbO ₃ , BaTiO ₃ , Pb(Zr,Ti)O ₃ , Pb(Mg,Nb)O ₃ -PbTiO ₃ , Pb(Zn,Nb)O ₃ -PbTiO ₃ or BiScO ₃ -PbTiO ₃ . According to specific embodiments, the shape and size of the soft magnetic layer 3 can also be changed accordingly.

The piezoelectric layer 2 and the piezoelectric layer 3 are connected by epoxy resin, and the piezoelectric layer electrode 1 is pasted on the corresponding piezoelectric layer 3 to form an electrical parallel connection. After the final assembly, the antenna as a whole is multi-layered structure.

Implementation case 1:

Referring to FIG. 2 , a multilayer magnetoelectric mechanical antenna in longitudinal vibration mode proposed by the present invention includes a piezoelectric layer electrode 1 , a piezoelectric layer 2 , and a piezoelectric layer 3 . The three piezoelectric layers 2 are identical, each piezoelectric layer 2 is polarized along the thickness direction, and is electrically connected in parallel. At this time, the antenna works in the d31 mode.

The main components of the multilayer magnetomechanical antenna are the piezoelectric layer 2 and the piezoelectric layer 3 from the center to both ends, and each component is bonded and stacked by epoxy resin in sequence along the thickness direction.

Referring to Fig. 2, in the present embodiment, the specific geometric dimensions of each component can be selected as follows: wherein the piezoelectric layer 3 is 100mm long, 2mm wide, and 0.25mm thick, and each piezoelectric layer 2 is 70mm long, 1.5mm wide, and 0.48mm thick , The thickness of the piezoelectric layer electrode 1 is 0.05mm.

In this embodiment, the multilayer magnetoelectric mechanical antenna is working in the d31 mode, and the alternating electric field is provided through the electrode leads in the three piezoelectric layers 2, and the three piezoelectric layers 2 will simultaneously undergo longitudinal stretching vibrations to generate When the bulk acoustic wave is transmitted to the piezoelectric layer 3 , the magnetic domains in the hysteretic material will move or flip, and then radiate the electromagnetic field outward. When the frequency of the alternating electric field is close to the first-order longitudinal vibration frequency of the multilayer magnetomechanical antenna, the antenna will produce mechanical resonance. At the same time, a DC bias magnetic field of certain strength needs to be provided during the working process of the antenna, the direction is along the antenna axis, and the magnitude is determined by the material of the piezoelectric layer 3 .

Fig. 3 is the COMSOL simulation result of this embodiment, the COMSOL model has been simplified, but it does not affect the credibility of the model solution. Figure 3 shows the first-order longitudinal vibration mode and its eigenfrequency of the multilayer magnetomechanical antenna.

FIG. 4 is a radiation-distance relation diagram of the present embodiment, and the receiver adopts an untuned coil.

FIG. 5 shows the variation of the resonant frequency of the multilayer magneto-electric mechanical antenna in this embodiment when the driving voltage increases, and the frequency when the induced voltage of the receiving coil reaches a peak value is taken as the resonant frequency.

Preferably, the piezoelectric material is PZT ceramics.

Preferably, the soft magnetic material is Metglas.

working principle:

The piezoelectric layer 2 is driven by applying an AC electric field through the piezoelectric layer electrode 1 , and the piezoelectric layer 2 generates mechanical strain, which is transmitted to the piezoelectric layer 3 through interface coupling. Based on the stress modulation of the magnetic domain state, an alternating electromagnetic field is generated.

According to the structural characteristics of the multilayer mechanical antenna, the specific preparation process of the multilayer mechanical antenna of the present invention can be summarized as follows:

1. Antenna structure design and simulation verification;

2. Material processing and packaging box preparation;

3. Preparation of the piezoelectric layer 2;

4. Preparation of the piezoelectric layer 3;

5. Bonding and compounding the piezoelectric layer 2 and the piezoelectric layer 3;

6. Paste the piezoelectric layer electrode 1 on the corresponding piezoelectric layer 3 to obtain the final prototype of the multilayer mechanical antenna.

In step 3, the preparation of the piezoelectric layer 2, the specific operation is as follows:

(1), take 4 pieces of piezoelectric ceramics, after ultrasonic cleaning, place them in a vacuum drying oven to dry for later use;

(2) The upper and lower surfaces of the piezoelectric ceramics are driven with a voltage of 1400V to complete the polarization process, and the polarization direction is marked for later use.

In step 4, the preparation of the piezoelectric layer 3 is performed as follows:

(1) Cut the soft magnetic material Metglas to a size of 100mm*10mm, wash it with 95% ethanol and then dry it, and take it out after drying;

(2) Spin-coat epoxy resin (West System105/206) on the surface of soft magnetic materials to complete the compounding of multi-layer soft magnetic materials;

(3), put the multi-layer soft magnetic material into a cold isostatic press and solidify it at room temperature for 24 hours and take it out;

In step five, the piezoelectric layer 2 and the piezoelectric layer 3 are bonded and compounded, and the specific operation is as follows:

(1), take the processed piezoelectric layer 2 and piezoelectric layer 3 to clean, wipe the bonding surface with alcohol and place it in a vacuum drying oven to dry for subsequent use;

(2) On a dry glass plate, apply epoxy resin evenly on the adhesive surface of the piezoelectric layer 2 and the piezoelectric layer 3, stack them together in turn, and finally use tape to fix them and apply pressure in the axial direction through gravity, room temperature Cured for 24 hours.

Implementation case 2:

Referring to FIG. 6 , a multilayer magnetoelectric mechanical antenna in longitudinal vibration mode proposed by the present invention includes a piezoelectric layer electrode 1 , a piezoelectric layer 2 , and a piezoelectric layer 3 . In this embodiment, the multilayer magnetoelectric mechanical antenna works in the d33 mode, the piezoelectric layer electrode 1 adopts an interdigital electrode, and the piezoelectric layer 2 adopts a piezoelectric fiber composite material of a piezoelectric fiber composite interdigital electrode to obtain a higher The electromechanical coupling coefficient of .

At this time, the piezoelectric layer 2 is made of piezoelectric fiber composite material and is longitudinally polarized. It forms a sandwich structure with the upper and lower piezoelectric layer electrodes 1. The three-layer structure is composited with epoxy resin. At this time, the antenna works in the d33 mode. According to specific embodiments, the shape and size of the piezoelectric layer 2 can also be changed accordingly. Since only the piezoelectric layer 2 is different from Embodiment 1, the preparation methods of other structures are the same as those in Embodiment 1 above.

The specific operation for the preparation of the piezoelectric layer 2 made of piezoelectric fiber composite material is as follows:

(1), making the interdigital electrodes constituting the piezoelectric layer electrodes 1, with a thickness of 40 μm;

(2) Ultrasonic cleaning of piezoelectric fibers, drying and taking out;

(3) Epoxy resin is spin-coated on the surface of the interdigital electrodes, and the piezoelectric fibers are placed in sequence to complete the composite of the piezoelectric material and the interdigital electrodes;

(4) Take out the piezoelectric fiber of the composite interdigitated electrode and solidify it at room temperature for 24 hours by vacuum compression technology to form a piezoelectric macroscopic fiber composite material;

(5) Place the piezoelectric fiber composite material in silicone oil, raise the DC voltage to 1400V and keep it for 15 minutes, after the polarization is completed;

(6) Spin-coat epoxy resin (WestSystem105/206) on the surface of the piezoelectric fiber composite material and the upper and lower soft magnetic material layers, bond the two parts, and take them out after curing.

Implementation case 3:

Referring to FIG. 7 , a multilayer magnetoelectric mechanical antenna in longitudinal vibration mode proposed by the present invention includes a piezoelectric layer electrode 1 , a piezoelectric layer 2 , and a piezoelectric layer 3 . The magnetoelectric mechanical antenna in this embodiment uses two pieces of soft magnetic material as the piezoelectric layer 3 and three pieces of piezoelectric ceramics as the piezoelectric layer to be stacked alternately, and works in the d31 mode. Compared with Example 1, the main difference is that the number of piezoelectric/piezomagnetic layers is different.

The embodiments of the present invention disclosed above are only used to help explain the present invention. The examples do not exhaust all details nor limit the invention to the specific embodiments described. Many modifications and variations can be made based on the contents of this specification. This description selects and specifically describes these embodiments in order to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention.

Claims (8)

1. a multilayer magnetoelectric mechanical antenna of longitudinal vibration mode, is characterized in that: comprise multilayer piezoelectric layer (3), multilayer piezoelectric layer (2) and multilayer piezoelectric layer electrode (1), multilayer The laminated magnetic layers (3) and the multilayer piezoelectric layers (2) are stacked alternately, and each layer of piezoelectric layers (3) is covered with piezoelectric layer electrodes (1) to form an electrical parallel connection. 2. the multilayer magneto-electric mechanical antenna of longitudinal vibration mode according to claim 1 is characterized in that: every laminated magnetic layer (3) is long 100mm, wide 2mm, thick 0.25mm, and every layer piezoelectric layer (2 ) is 70mm long, 1.5mm wide, and 0.48mm thick, and each piezoelectric layer electrode (1) is 0.05mm thick, and the piezoelectric layer electrode (1) is made of copper. 3. The multilayer magneto-electric mechanical antenna of longitudinal vibration mode according to claim 1, characterized in that: said piezoelectric layer (3) is made of soft magnetic blocks or multilayer composites of soft magnetic tapes, wherein The soft magnetic material is one of Metglas, Fe-Ga alloy, Terfernol-D alloy, Fe-Ni alloy, FeCo, FeCoB, FeGaB, NiZn ferrite and Ni metal, connected by epoxy resin. 4. the multilayer magneto-electric mechanical antenna of longitudinal vibration mode according to claim 1, is characterized in that: the piezoelectric material of described piezoelectric layer (2) comprises piezoelectric ceramics and piezoelectric single crystal, piezoelectric material It is one of LiNbO ₃ , BaTiO ₃ , Pb(Zr,Ti)O ₃ , Pb(Mg,Nb)O ₃ -PbTiO ₃ , Pb(Zn,Nb)O ₃ -PbTiO ₃ or BiScO ₃ -PbTiO ₃ . 5. The multilayer magnetoelectric mechanical antenna in longitudinal vibration mode according to claim 1, characterized in that: the piezoelectric layer (2) and the piezoelectric layer (3) are connected by epoxy resin. 6. The multilayer magneto-electric mechanical antenna of longitudinal vibration mode according to claim 1, characterized in that: each layer of piezoelectric layer (2) is polarized along the thickness direction, and takes electrical parallel connection, and now the antenna works at d31 model. 7. The multilayer magneto-electric mechanical antenna of longitudinal vibration mode according to claim 6, is characterized in that: piezoelectric layer (2) also can adopt piezoelectric macro fiber composite material, adopts longitudinal polarization mode, now antenna Works in d33 mode. 8. A method for preparing the multilayer magneto-electric mechanical antenna of the longitudinal vibration mode according to claim 1, characterized in that: specifically comprising the following steps: (1) Antenna structure design and simulation verification; (2), material processing, packing box preparation; (3), the preparation of piezoelectric layer (2); (4), preparation of the piezoelectric layer (3); (5), bonding and compounding the piezoelectric layer (2) and the piezoelectric layer (3); (6) Pasting the piezoelectric layer electrode (1) on the corresponding piezoelectric layer (3) to obtain the final prototype of the multilayer mechanical antenna.

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