A functional gradient magnetoelectric transmitting antenna prepared by annealing method

Abstract

The application relates to a functional gradient magnetoelectric emission antenna prepared by an annealing method. The functional gradient magnetoelectric emission antenna comprises a piezoelectric layer and a magnetostrictive layer; the magnetostrictive layer comprises an annealed magnetostrictive layer I, a non-annealed magnetostrictive layer II, a non-annealed magnetostrictive layer III and an annealed magnetostrictive layer IV, the magnetostrictive layer I and the magnetostrictive layer II are arranged on the upside of the piezoelectric layer, the magnetostrictive layer III and the magnetostrictive layer IV are arranged on the downside of the piezoelectric layer, and the piezoelectric layer and the magnetostrictive layer are bonded through epoxy resin. The functional gradient magnetoelectric emission antenna is based on the principle of the sound wave excitation type magnetoelectric antenna, realizes self-bias operation through the magnetic interaction between the functional gradient structure composed of two different magnetostrictive materials, does not need an additional direct current bias magnetic field, and has the advantages of self-bias, small size, low energy consumption, high radiation efficiency and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of low frequency long wave communication, and particularly relates to a functional gradient magnetoelectric emission antenna prepared by an annealing method. BACKGROUND

[0002] Antenna is a key component in electromagnetic wave communication process, and can be generally classified into traditional antenna and mechanical antenna according to the difference of radiation mechanism. The traditional antenna works depending on electromagnetic wave resonance, and its size is equivalent to the wavelength to maintain the best performance. The antenna applied to low frequency communication technology for underwater communication needs a huge size, and the key to promote the development of underwater antenna device is the miniaturization of the device. The magnetoelectric material can realize bidirectional conversion of magnetic signal and electric signal based on magnetoelectric effect, and the inverse magnetoelectric effect can radiate electromagnetic wave. The magnetoelectric antenna based on acoustic wave resonance operation is also easier to realize miniaturization. Generally, the magnetostrictive material needs to be applied with a certain direct current bias magnetic field to play a better performance, so the magnetoelectric antenna needs a certain external direct current bias magnetic field when working, but the external bias will bring problems such as large volume and increased noise. Therefore, the self-bias and better radiation performance of the magnetoelectric antenna are urgent problems to be solved. SUMMARY

[0003] In view of the above problems, the present application provides a functional gradient magnetoelectric emission antenna prepared by an annealing method. The functional gradient magnetoelectric emission antenna of the present application is based on the new principle of acoustic wave excitation type magnetoelectric antenna, and the magnetic interaction between the functional gradient structure composed of two different magnetostrictive materials can realize self-bias operation, that is, without external direct current bias magnetic field, thereby reducing the volume and realizing the breakthrough of low frequency communication system, and the functional gradient magnetoelectric emission antenna has the advantages of self-bias, small size, low energy consumption, high radiation efficiency and the like.

[0004] The technical scheme of the present application is as follows:

[0005] A functional gradient magnetoelectric emission antenna, comprising a piezoelectric layer and a magnetostrictive layer; the magnetostrictive layer comprises a magnetostrictive layer I, a magnetostrictive layer II, a magnetostrictive layer III and a magnetostrictive layer IV; the magnetostrictive layer II is arranged on the upper surface of the piezoelectric layer, and the magnetostrictive layer III is arranged on the lower surface of the piezoelectric layer; the magnetostrictive layer I is arranged on the side of the magnetostrictive layer II away from the piezoelectric layer; the magnetostrictive layer IV is arranged on the side of the magnetostrictive layer III away from the piezoelectric layer; and the piezoelectric layer and the magnetostrictive layer are bonded by epoxy resin.

[0006] Further, the magnetostrictive layer I, the magnetostrictive layer II, the magnetostrictive layer III and the magnetostrictive layer IV each comprise two or more magnetostrictive material layers.

[0007] Further, each raw material layer of the magnetostrictive layer I and the magnetostrictive layer IV is subjected to annealing treatment; each raw material layer of the magnetostrictive layer II and the magnetostrictive layer III is not subjected to annealing treatment.

[0008] Further, the annealing treatment is that the annealing furnace is preheated to 20-30 DEG C, each raw material layer is placed in the annealing furnace, heated to 400-500 DEG C at 1-5 DEG C / min, and then naturally cooled.

[0009] Further, the annealing parameters are optimized in the present application, the annealing treatment is carried out in a muffle furnace, the annealing atmosphere is atmospheric environment, the initial temperature is 25 DEG C, the heating rate is 5 DEG C / min, the annealing temperature is 400 DEG C, 425 DEG C, 450 DEG C, 475 DEG C and 500 DEG C respectively, the holding time is 20 min, and then naturally cooled.

[0010] Further, the magnetostrictive material layers are bonded by epoxy resin.

[0011] Further, the functional gradient is obtained by bonding the annealed and unannealed magnetostrictive layers, including the magnetostrictive layer I and the magnetostrictive layer II to form a functional gradient structure I, and the magnetostrictive layer III and the magnetostrictive layer IV to form a functional gradient structure II.

[0012] Further, the material of the magnetostrictive raw material layer includes one of Terfenol-D, FeGa and Metglas; preferably, the material of the magnetostrictive raw material layer is Metglas.

[0013] Further, the surfaces of the magnetostrictive layer I and the magnetostrictive layer IV away from the piezoelectric layer are led by silver paste lead wires.

[0014] Further, the material of the piezoelectric layer includes one of lead zirconate titanate-based piezoelectric material, lead magnesium niobate-based piezoelectric material, barium titanate-based piezoelectric material and potassium sodium niobate-based piezoelectric material; preferably, the material of the piezoelectric layer is lead zirconate titanate-based piezoelectric material.

[0015] Further, the material of the piezoelectric layer is PZT-5.

[0016] A preparation method of the functional gradient magnetoelectric transmitting antenna, comprising the following steps:

[0017] (1) epoxy resin is configured for standby;

[0018] (2) the epoxy resin prepared in step (1) is coated between the magnetostrictive raw material layers, and after curing, the magnetostrictive layer II and the magnetostrictive layer III are obtained;

[0019] (3) taking the magnetostrictive material layer to perform annealing heat treatment, coating the epoxy resin prepared in step (1) between the magnetostrictive material layers, and curing to obtain magnetostrictive layer I and magnetostrictive layer IV, respectively;

[0020] (4) bonding the magnetostrictive layer II and the magnetostrictive layer III to the upper and lower sides of the piezoelectric layer with epoxy resin, respectively, then bonding the magnetostrictive layer I to the surface of the magnetostrictive layer II with epoxy resin, and bonding the magnetostrictive layer IV to the surface of the magnetostrictive layer III with epoxy resin, removing the excess epoxy resin by vacuumizing, and curing to obtain a composite structure;

[0021] (5) coating a conductive silver paste layer on the upper and lower surfaces of the composite structure prepared in step (4), and leading the wires out of the conductive silver paste layer to obtain a functional gradient magneto-electric transmitting antenna.

[0022] The application has the beneficial technical effects that:

[0023] The functional gradient magneto-electric transmitting antenna designed in the application stacks the piezoelectric material and the magnetostrictive material together through the epoxy resin bonding layer, combines the inverse piezoelectric effect of the piezoelectric material and the piezomagnetic effect of the magnetostrictive material, applies a specific frequency driving voltage to both ends of the piezoelectric material, realizes the electric energy-mechanical energy-magnetic conversion through the inverse magneto-electric effect, triggers the magnetic layer magnetization oscillation, generates a time-varying magnetic field, and realizes the mutual conversion of the time-varying magnetic field and the time-varying electric field to realize the radiation of electromagnetic waves.

[0024] Further, the application proposes to use the annealing process to heat treat the magnetostrictive material, and simultaneously composite the magnetostrictive material with the magnetostrictive material without annealing treatment, realizes the self-bias effect through the magnetic interaction between the functional gradient structures composed of different magnetostrictive materials, and overcomes the problems of large volume and increased noise caused by the external direct current bias field.

[0025] The functional gradient magneto-electric transmitting antenna designed in the application realizes the self-bias condition, and compared with the same size electrically small antenna under the same power driving, the radiation intensity is improved by 25 times. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of the functional gradient magneto-electric transmitting antenna of the application;

[0027] In the figure: 1, magnetostrictive layer I; 2, magnetostrictive layer II; 3, piezoelectric layer; 4, magnetostrictive layer III; 5, magnetostrictive layer IV; 6, wire.

[0028] Figure 2 It is a schematic diagram of the change of the inverse magneto-electric coefficient of the functional gradient magneto-electric transmitting antenna described in Example 3 of the application with the bias magnetic field.

[0029] Figure 3This is a schematic diagram showing the variation of the inverse magnetoelectric coefficient with frequency of the functionally graded magnetoelectric transmitting antenna described in Embodiment 3 of the present invention under a zero bias magnetic field.

[0030] Figure 4 This is a schematic diagram showing the relationship between the magnetic induction intensity of the functionally graded magnetoelectric transmitting antenna and the driving power of the magnetoelectric antenna as described in Embodiment 3 of the present invention.

[0031] Figure 5 This diagram illustrates the attenuation of magnetic flux density with distance for the functionally graded magnetoelectric transmitting antenna described in Embodiment 3 of the present invention and a conventional circular loop antenna as a comparison.

[0032] Figure 6 This is the near-field radiation pattern of the functionally graded magnetoelectric transmitting antenna described in Embodiment 3 of the present invention.

[0033] Figure 7 The diagram shows the quasi-static self-biasing effect of the functionally graded magnetoelectric transmitting antenna prepared according to an embodiment of the present invention.

[0034] Figure 8 A schematic diagram showing the variation of the inverse magnetoelectric coefficient with frequency under zero bias field for the functionally graded magnetoelectric transmitting antenna prepared according to an embodiment of the present invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] The self-biasing of this invention utilizes the magnetic interaction caused by the difference in magnetic properties between unannealed and annealed magnetostrictive materials. Under the action of an external magnetic field, the magnetic moments are arranged in an orderly manner due to the magnetic interaction, resulting in a built-in magnetic field, thereby achieving self-biasing.

[0037] like Figure 1 As shown, the functionally graded magnetoelectric transmitting antenna of the present invention includes a magnetostrictive layer I1, a magnetostrictive layer II2, a piezoelectric layer 3, a magnetostrictive layer III4, and a magnetostrictive layer IV5. The magnetostrictive layers II2 and III4 are respectively disposed on the upper and lower sides of the piezoelectric layer 3. The magnetostrictive layer I1 is disposed on the side of the magnetostrictive layer II2 away from the piezoelectric layer 3, and the magnetostrictive layer IV5 is disposed on the side of the magnetostrictive layer III4 away from the piezoelectric layer. These layers are bonded together with epoxy resin to form a composite structure. The conductor 6 is fixed to the surface of the electrode layer using conductive silver paste.

[0038] A functionally graded magnetoelectric transmitting antenna, which works as follows: a specific frequency driving voltage is applied to both ends of a piezoelectric material layer, and through its inverse magnetoelectric effect, an electric energy-mechanical energy-magnetic conversion is realized, a magnetic layer magnetization oscillation is triggered, a time-varying magnetic field is generated, the time-varying magnetic field and the time-varying electric field are converted into each other, and electromagnetic wave radiation is realized; meanwhile, the magnetostrictive raw material layer is heat treated using an annealing process, and then the annealed magnetostrictive layer is obtained by resin bonding, and the unannealed magnetostrictive layer is obtained by resin bonding the magnetostrictive raw material layer without annealing; the two different heat treated magnetostrictive layers are combined, and the self-bias effect is realized through the magnetic interaction between the functionally graded structure composed of the heat treated and unheat treated magnetostrictive layers.

[0039] Embodiment 1:

[0040] A functionally graded magnetoelectric transmitting antenna, which comprises a piezoelectric layer and a magnetostrictive layer. 3 The piezoelectric layer is PZT-5, with a size of 60x20x0.2mm 3 The magnetostrictive material is Metglas, and each of the four layers of magnetostrictive layer has a size of 140x20x0.042mm 3 Each layer of magnetostrictive layer is bonded by two pieces of Metglas. The magnetostrictive layer II 2 and the magnetostrictive layer III 4 are respectively arranged on the upper and lower sides of the piezoelectric layer, the magnetostrictive layer I 1 is arranged on the side of the magnetostrictive layer II 2 away from the piezoelectric layer, the magnetostrictive layer IV 5 is arranged on the side of the magnetostrictive layer III 4 away from the piezoelectric layer, the piezoelectric layer is bonded with the magnetostrictive layers by epoxy resin to form a magnetoelectric composite structure; the magnetostrictive raw material layers and the magnetostrictive layers are bonded by resin.

[0041] The functionally graded magnetoelectric transmitting antenna further comprises two wires, which are respectively led out from the surfaces of the magnetostrictive layer I 1 and the magnetostrictive layer IV 5 by using conductive silver paste.

[0042] The preparation method of the functionally graded magnetoelectric transmitting antenna is as follows:

[0043] (1) Prepare epoxy resin, mix epoxy resin A component and curing agent B according to the proportion, stir and put into an 80℃ oven for 1 minute, and reserve;

[0044] (2) Prepare the magnetostrictive layer II and the magnetostrictive layer III: wipe each layer of Metglas clean with dust-free paper and alcohol, evenly spread epoxy resin on the Metglas with a blade, then bond two layers of Metglas with a size of 140x20x0.021mm 3 to obtain a magnetostrictive layer II, and repeat the above work to obtain another magnetostrictive layer III;

[0045] (3) Preparation of magnetostrictive layer I and magnetostrictive layer IV: First, the annealing treatment of magnetostrictive raw material layer is prepared, that is, the annealing furnace is preheated to 25°C, then the magnetostrictive raw material layer Metglas is placed in the annealing furnace, heated to 400°C at a rate of 5°C / min, and the holding time is 20 min, then naturally cooled to obtain the annealing treatment of magnetostrictive raw material layer, each annealing treatment of Metglas is cleaned with dust-free paper and alcohol, and epoxy resin is coated between the two layers of annealing treatment of Metglas to obtain the magnetostrictive layer I and the magnetostrictive layer IV;

[0046] (4) After bonding, the magnetostrictive layer I and the magnetostrictive layer IV are placed in a vacuum bag, and a layer of PTFE (polytetrafluoroethylene) film is placed on the upper and lower surfaces of each magnetostrictive layer I and IV to prevent bonding, then vacuum is applied, and then it is placed in an oven for curing, and after complete solidification, the excess epoxy resin is scraped off with a blade.

[0047] (5) The magnetostrictive layer II and the magnetostrictive layer III are bonded to the upper and lower sides of the piezoelectric layer using epoxy resin, respectively, and then the magnetostrictive layer I and the magnetostrictive layer IV are bonded to one side of the magnetostrictive layer II and one side of the magnetostrictive layer III using epoxy resin, respectively, and then vacuum is applied to remove excess epoxy resin, and then it is cured to obtain a composite structure.

[0048] Example 2:

[0049] Example 2 differs from Example 1 only in that the heat treatment temperature of Metglas used to prepare magnetostrictive layer I and magnetostrictive layer IV is 425°C, that is, heated to 425°C at a rate of 5°C / min, and the holding time is 20 min, and the rest of the parameters and preparation methods are the same as those of Example 1.

[0050] Example 3:

[0051] Example 3 differs from Example 1 only in that the heat treatment temperature of Metglas used to prepare magnetostrictive layer I and magnetostrictive layer IV is 450°C, that is, heated to 450°C at a rate of 5°C / min, and the holding time is 20 min, and the rest of the parameters and preparation methods are the same as those of Example 1.

[0052] Example 4:

[0053] Example 4 differs from Example 1 only in that the heat treatment temperature of Metglas used to prepare magnetostrictive layer I and magnetostrictive layer IV is 475°C, that is, heated to 475°C at a rate of 5°C / min, and the holding time is 20 min, and the rest of the parameters and preparation methods are the same as those of Example 1.

[0054] Example 5:

[0055] Example 2 differs from Example 1 only in that the heat treatment temperature of Metglas used to prepare magnetostrictive layer I and magnetostrictive layer IV is 500°C, i.e. heating to 500°C at 5°C / min, the holding time is 20 min, and the rest of the parameters and the preparation method are the same as in Example 1.

[0056] Example 6:

[0057] Example 6 differs from Example 1 only in that the heating rate of the annealing furnace is 1°C / min, i.e. heating to 400°C at 1°C / min, the holding time is 20 min, and the rest of the parameters and the preparation method are the same as in Example 1.

[0058] Example 7:

[0059] Example 7 differs from Example 1 only in that the heating rate of the annealing furnace is 3°C / min, i.e. heating to 400°C at 3°C / min, the holding time is 20 min, and the rest of the parameters and the preparation method are the same as in Example 1.

[0060] Example 8:

[0061] Example 8 differs from Example 1 only in that the holding time of the annealing furnace is 10 min, i.e. heating to 400°C at 5°C / min, the holding time is 10 min, and the rest of the parameters and the preparation method are the same as in Example 1.

[0062] Example 9:

[0063] Example 9 differs from Example 1 only in that the holding time of the annealing furnace is 15 min, i.e. heating to 400°C at 5°C / min, the holding time is 15 min, and the rest of the parameters and the preparation method are the same as in Example 1.

[0064] Example 10:

[0065] Example 10 differs from Example 1 only in that the piezoelectric layer material used is a lead magnesium niobate-based piezoelectric material, and the magnetostrictive body is FeGa. The rest of the parameters and the preparation method are the same as in Example 1.

[0066] Example 11:

[0067] Example 11 differs from Example 1 only in that the piezoelectric layer material used is a potassium sodium niobate-based piezoelectric material, and the magnetostrictive body is Terfenol-D. The rest of the parameters and the preparation method are the same as in Example 1.

[0068] Comparative Example 1:

[0069] Comparative Example 1 is a conventional circular loop electric antenna of the same size as Example 3, i.e. the area of the circular loop antenna is equal to the area of the magnetoelectric composite (the area of the circular loop antenna is equal to the area of the magnetoelectric composite, 140*20=2800mm 2 ). The radiation intensity and efficiency of the magnetoelectric antenna and the loop antenna are compared at the same driving frequency.

[0070] Test Example:

[0071] The magnetoelectric antenna prepared in Example 3 is connected to the test system, a fixed input AC voltage signal is applied, the size of the DC bias magnetic field is changed, the size of the radiated magnetic field is measured to obtain the inverse magnetoelectric coefficient, and thus the change of the inverse magnetoelectric coefficient with the bias magnetic field is determined, and the results are shown in Figure 2 . As can be seen from the figure, the magnetoelectric antenna prepared in Example 3 has a self-bias effect, i.e. has a non-zero inverse magnetoelectric coefficient under zero bias field.

[0072] The magnetoelectric antenna prepared in Example 3 is connected to the test system, the amplitude of the input AC voltage signal is fixed under zero bias magnetic field, the frequency of the input AC voltage signal is changed, and then the size of the magnetic field radiated by the magnetoelectric antenna under different frequencies is measured to obtain the relationship between the inverse magnetoelectric coefficient under zero bias and the frequency of the driving voltage signal. The results are shown in Figure 3 . The magnetoelectric antenna prepared in Example 3 obtains the optimal performance at a resonant frequency of 17.35 kHz, so the magnetoelectric antenna works near the resonant frequency.

[0073] The magnetoelectric antenna prepared in Example 3 is connected to the test system, an AC signal with a frequency of 17.35 kHz is input under zero bias magnetic field, the size of the driving power is changed, and the size of the magnetic field radiated by the magnetoelectric antenna is measured to obtain the relationship between the magnetic induction intensity and the driving power under zero bias. The results are shown in Figure 4 . As can be seen from the figure, the radiation intensity of the magnetoelectric antenna prepared in Example 3 is closely related to the driving power, the greater the driving power, i.e. the greater the applied voltage, the stronger the radiation intensity of the antenna.

[0074] Figure 5 The relationship between the magnetic induction intensity of the antennas of Example 3 and Comparative Example 1 and the distance under the maximum driving power shown in Figure 4 is shown in Figure 5 . The electromagnetic wave signal radiated by the magnetoelectric antenna decays with the distance to the third power. Under the same driving power, the radiation intensity of the magnetoelectric antenna is about 25 times that of the circular loop antenna of the same size.

[0075] The formula of the theoretical radiation magnetic flux density of the near field of the circular loop antenna is as follows:

[0076]

[0077]

[0078] wherein: B r is the radial magnetic flux density; B θ is the tangential magnetic flux density; μ0 is the free space permeability (4π x 10 -7 H / m), η is the radiation impedance of free space (377 Ω), k is the radiation coefficient related to the wavelength λ Z0 is the transmission line impedance (Z0 = 50 Ω); R r is the radiation impedance of the antenna S is the area of the loop antenna); P in is the input power of the antenna, which is equal to that of the magneto-electric antenna; r is the distance between the receiving end and the antenna.

[0079] As Figure 5 shown, the measured radiation intensity of the magneto-electric antenna is about 25 times higher than the theoretically calculated value of the loop antenna. The radiation efficiency η ME of the magneto-electric antenna is related to the radiation efficiency η loop of the loop antenna as follows:

[0080]

[0081] The radiation efficiency calculation formula of the loop antenna is as follows:

[0082]

[0083] wherein: B ME and B loop are the magnetic flux densities caused by the magneto-electric antenna and the loop antenna at the same distance r, respectively. Thus, the radiation efficiency of Example 3 is 4.96 x 10 -17 , which is 2 orders of magnitude higher than that of the loop antenna.

[0084] Figure 6 is the near-field radiation pattern of the magneto-electric antenna of Example 3. As Figure 6 can be seen, the magneto-electric antenna prepared in Example 3 has obvious directivity.

[0085] The present application investigates the effects of different annealing conditions on self-bias and magneto-electric antenna performance. In the magneto-electric antennas prepared in Examples 1-5, five annealing temperatures are used to compare the effects of different annealing temperatures on the performance of the magneto-electric antenna, and the results are shown in Figures 7-8 As Figure 7 can be seen, the magneto-electric antenna prepared in the present application has a self-bias effect, i.e., has a non-zero inverse magneto-electric coefficient under zero bias field, and the best annealing temperature is 450°C through comparison. Figure 8The schematic diagram of the inverse magneto-electric coefficient of the magneto-electric antenna prepared in the examples 1-5 changing with the frequency under the zero bias magnetic field is shown in the figure, and it can be seen from the figure that the performance of 450℃ (example 3) is optimal, and therefore the optimal annealing process is determined as follows: the annealing furnace is a muffle furnace, the annealing atmosphere is an atmospheric environment, the starting temperature is 25℃, the heating speed is 5℃ / min, the annealing temperature is 450℃, the holding time is 20 min, and the cooling is natural cooling.

[0086] The above merely describes the preferred embodiments of the present application, and the present application is not limited to the above examples. It can be understood that other improvements and changes directly derived or thought by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A functionally graded magnetoelectric transmitting antenna, characterized in that, The functionally graded magnetoelectric transmitting antenna includes a piezoelectric layer and a magnetostrictive layer; the magnetostrictive layer includes magnetostrictive layer I, magnetostrictive layer II, magnetostrictive layer III, and magnetostrictive layer IV; magnetostrictive layer II is disposed on the upper surface of the piezoelectric layer, and magnetostrictive layer III is disposed on the lower surface of the piezoelectric layer; magnetostrictive layer I is disposed on the side of magnetostrictive layer II away from the piezoelectric layer; magnetostrictive layer IV is disposed on the side of magnetostrictive layer III away from the piezoelectric layer; the piezoelectric layer and the magnetostrictive layer are bonded together with epoxy resin; Each raw material layer of magnetostrictive layer I and magnetostrictive layer IV has undergone annealing treatment; each raw material layer of magnetostrictive layer II and magnetostrictive layer III has not undergone annealing treatment. The annealing process involves preheating the annealing furnace to 20-30°C, placing each material layer in the annealing furnace, heating it to 400°C-500°C at a rate of 1-5°C / min, holding it at that temperature for 10-20 min, and then allowing it to cool naturally. The magnetostrictive material layers are bonded together with epoxy resin.

2. The functionally graded magnetoelectric transmitting antenna according to claim 1, characterized in that, The magnetostrictive layer I, magnetostrictive layer II, magnetostrictive layer III, and magnetostrictive layer IV each contain two or more magnetostrictive material layers.

3. The functionally graded magnetoelectric transmitting antenna according to claim 2, characterized in that, The material of the magnetostrictive raw material layer includes one of Terfenol-D, FeGa, and Metglas.

4. The functionally graded magnetoelectric transmitting antenna according to claim 2, characterized in that, The material of the magnetostrictive raw material layer is Metglas.

5. The functionally graded magnetoelectric transmitting antenna according to claim 1, characterized in that, The surfaces of both magnetostrictive layer I and magnetostrictive layer IV that are away from the piezoelectric layer are led out with wires through silver paste.

6. The functionally graded magnetoelectric transmitting antenna according to claim 1, characterized in that, The material of the piezoelectric layer includes one of lead zirconate titanate-based piezoelectric material, lead magnesium niobate-based piezoelectric material, barium titanate-based piezoelectric material, and potassium sodium niobate-based piezoelectric material.

7. The functionally graded magnetoelectric transmitting antenna according to claim 1, characterized in that, The piezoelectric layer is made of lead zirconate titanate-based piezoelectric material.

8. The functionally graded magnetoelectric transmitting antenna according to claim 1, characterized in that, The material of the piezoelectric layer is PZT-5.

9. A method for fabricating a functionally graded magnetoelectric transmitting antenna according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: (1) Prepare epoxy resin for later use; (2) The epoxy resin prepared in step (1) is coated between the magnetostrictive raw material layers and cured to obtain magnetostrictive layer II and magnetostrictive layer III. (3) After the magnetostrictive material layer is subjected to annealing heat treatment, the epoxy resin prepared in step (1) is coated between the magnetostrictive material layers. After curing, magnetostrictive layer I and magnetostrictive layer IV are obtained respectively. (4) The magnetostrictive layer II and the magnetostrictive layer III are bonded to the upper and lower sides of the piezoelectric layer respectively with epoxy resin. Then the magnetostrictive layer I is bonded to the surface of the magnetostrictive layer II with epoxy resin. The magnetostrictive layer IV is bonded to the surface of the magnetostrictive layer III with epoxy resin. The excess epoxy resin is removed by vacuuming and cured to obtain the composite structure. (5) Coat the upper and lower surfaces of the composite structure prepared in step (4) with conductive silver paste layer, and lead the wire out from the conductive silver paste layer to obtain a functionally graded magnetoelectric transmitting antenna.

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