A low-frequency miniaturized electromagnetic-acoustic radiator and a preparation method thereof

Abstract

The application discloses a low-frequency miniaturized electromagnetic-sound radiator and a preparation method thereof, and belongs to the technical field of communication. The electromagnetic-sound radiator comprises, from top to bottom, an upper magnet, an upper magnetostrictive sheet, an upper electrode, a C-axis polarized piezoelectric layer, a lower electrode, a lower magnetostrictive sheet and a lower magnet, and the different layers are bonded by epoxy resin. The upper electrode and the lower electrode are both interdigital electrodes, and the upper magnet and the lower magnet are used for clamping the magnetostrictive sheet-piezoelectric layer composite layer, aiming to improve the stress transmission coefficient. An excitation signal is input from the interdigital electrode, the piezoelectric layer is excited to vibrate, sound wave radiation is generated, meanwhile, the piezoelectric layer vibration is transmitted to the magnetostrictive sheet, and the magnetostrictive sheet is magnetized to oscillate and radiate electromagnetic waves. The application has the characteristics of double modes, small size, low power consumption and strong signal, can significantly reduce the size of a low-frequency communication system, and is especially suitable for emergency communication scenes such as mine communication.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a low-frequency miniaturized electromagnetic-acoustic radiator and its fabrication method. Background Technology

[0002] Low-frequency electromagnetic waves, due to their strong penetrating power, show great potential in cross-domain communication. However, the matching relationship between antenna aperture and wavelength leads to the large size of low-frequency antennas, especially at the transmitting end. When the antenna aperture is less than one-tenth of the electromagnetic field wavelength, the antenna's radiation performance is significantly reduced. Currently, the aperture of low-frequency communication antennas in developed countries such as the United States often reaches tens of kilometers. The magnetoelectric effect based on magnetostrictive and piezoelectric materials provides a new working mechanism for antennas. This mechanism achieves the interconversion of electromagnetic field and oscillating current through the combination of magnetoelectric effect and mechanical resonance, without requiring the antenna size to resonate with a specific electromagnetic wave wavelength. The antenna size will no longer be limited by the electromagnetic wave wavelength, providing an excellent solution for manufacturing miniaturized low-frequency antennas.

[0003] Antennas based on the magnetoelectric effect can reduce their physical size to one-thousandth of the operating wavelength, which is one to two orders of magnitude smaller than the most advanced conventional integrated antennas while maintaining the same performance. Furthermore, it is worth mentioning that antennas based on the magnetoelectric effect do not require complex impedance matching networks, enabling the realization of miniaturized cross-domain communication systems.

[0004] The invention patent application with application number 202111308829.4 discloses a method for preparing a cantilever beam structure magnetoelectric antenna, a testing method, and the magnetoelectric antenna itself. The function of the magnetoelectric antenna is to receive electromagnetic waves, but it cannot radiate low-frequency electromagnetic waves.

[0005] In addition, the paper "A Low Frequency Mechanical Transmitter Based on Magnetoelectric Heterostructures Operated at Their Resonance Frequency" reported by the Virginia Tech research team, although also a radiating antenna based on the magnetoelectric effect, has a lower signal radiation capability. Summary of the Invention

[0006] To address the aforementioned problems, this invention aims to provide a low-frequency miniaturized electromagnetic-acoustic radiator for cross-domain communication and its fabrication method. The electromagnetic-acoustic radiator can radiate low-frequency electromagnetic waves and sound waves, and has strong signal radiation capability, low power consumption, simple structure, small size, and is easy to carry.

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

[0008] A low-frequency miniaturized electromagnetic-acoustic radiator is characterized by comprising, from top to bottom, an upper magnetostrictive sheet, an upper electrode, a piezoelectric layer, a lower electrode, and a lower magnetostrictive sheet. The upper magnetostrictive sheet, the upper electrode, the piezoelectric layer, the lower electrode, and the lower magnetostrictive sheet have the same width, their geometric centers are located on the same vertical line, and the lengths of the upper and lower magnetostrictive sheets are greater than the lengths of the upper electrode, the piezoelectric layer, and the lower electrode.

[0009] Furthermore, the top of the upper magnetostrictive sheet is provided with an upper magnet, and the bottom of the lower magnetostrictive sheet is provided with a lower magnet. The geometric centers of the upper magnet and the lower magnet are also located on the same vertical line as the centers of the upper magnetostrictive sheet and the lower magnetostrictive sheet.

[0010] Furthermore, the polarization direction of the upper and lower magnetostrictive sheets is horizontal, and the polarization direction of the piezoelectric layer is the thickness direction.

[0011] Furthermore, both the upper and lower electrodes are interdigitated electrodes, and the interdigitated electrodes are in close contact with the piezoelectric layer.

[0012] Furthermore, the material of the piezoelectric layer is one or more of AlN, ZnO, PZT, LiNbO3, LiTaO3 and their doped products.

[0013] Furthermore, the materials of the upper and lower electrodes are any one of Au, Cu, and copper; and the thickness of both the upper and lower electrodes is 20um to 100um.

[0014] Furthermore, both the upper and lower magnets are made of neodymium iron boron.

[0015] Furthermore, a method for fabricating a low-frequency miniaturized electromagnetic-acoustic radiator is characterized by comprising the following steps:

[0016] S1: Material preparation;

[0017] S2: Bond and fix the upper electrode and the lower electrode to the top and bottom of the piezoelectric layer, respectively;

[0018] S3: The upper magnetostrictive sheet is bonded and fixed to the top of the upper electrode, and the lower magnetostrictive sheet is bonded and fixed to the bottom of the lower electrode.

[0019] S4: Clamp and fix the upper magnet and the lower magnet to the outside of the upper magnetostrictive sheet and the lower magnetostrictive sheet respectively;

[0020] S5: Solder leads to the upper and lower electrodes respectively to bring out the circuit interface.

[0021] Furthermore, the specific operation of step S1 includes the following steps:

[0022] S101: Cut a C-axis polarized piezoelectric sheet to serve as a piezoelectric layer;

[0023] S102: Cut two magnetostrictive sheets of the same size, which will be used as the upper magnetostrictive sheet and the lower magnetostrictive sheet, respectively.

[0024] S103: Prepare a pair of PI substrate interdigitated electrodes, which will be used as the upper and lower layer electrodes, respectively.

[0025] S104: Prepare magnet blocks, which will be used as the upper and lower layer magnets respectively.

[0026] The beneficial effects of this invention are:

[0027] 1. The electromagnetic-acoustic radiator in this invention has the function of dual-channel communication of electromagnetic waves and acoustic waves, which broadens the way of cross-domain communication, has a wider range of applications, and stronger security; it is also easy to manufacture, small in size (10mm*80mm*5mm), strong in signal radiation (the electromagnetic wave intensity can reach the uT level when the radiation distance is 1m), and low in energy consumption (1w).

[0028] 2. The electromagnetic-acoustic radiator in this invention has an antenna size much smaller than the wavelength of the matching electromagnetic waves. By arraying multiple radiators, the signals are superimposed, which can significantly enhance the radiation signal intensity of the electromagnetic-acoustic radiator while ensuring a small size.

[0029] 3. The electromagnetic-acoustic radiator in this invention has dual electromagnetic and acoustic operating modes. Besides radiating electromagnetic-acoustic signals, it also has the ability to receive low-frequency electromagnetic and acoustic signals. In emergency communication conditions such as cross-domain communication, it can determine the communication distance by the degree of electromagnetic wave attenuation and improve the detection rate of weak communication information through acoustic-electromagnetic signal interaction. The electromagnetic and acoustic signals operate at the same frequency and are specially designed to achieve electromagnetic-acoustic signal radiation (3kHz-100kHz). Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the electromagnetic-acoustic radiator structure of the present invention.

[0031] Figure 2 This is the interdigitated electrode structure of the upper and lower electrodes of the present invention.

[0032] Figure 3 This is a schematic diagram illustrating the vibration mode of the piezoelectric layer radiating acoustic waves according to the present invention.

[0033] Figure 4 This describes the vibration mode of the electromagnetic waves radiated by the magnetostrictive sheet of this invention.

[0034] Figure 5 This is a schematic diagram of the electromagnetic wave signal output of the electromagnetic-acoustic radiator of the present invention.

[0035] Among them, 1-upper magnetostrictive sheet, 2-upper electrode, 3-piezoelectric layer, 4-lower electrode, 5-lower magnetostrictive sheet, 6-upper magnet, 7-lower magnet. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] Example 1:

[0038] A low-frequency miniaturized electromagnetic-acoustic radiator, the structure of which is shown in the attached figure. Figure 1 As shown, from top to bottom, it includes an upper magnet 6, an upper magnetostrictive sheet 1, an upper electrode 2, a piezoelectric layer 3, a lower electrode 4, a lower magnetostrictive sheet 5, and a lower magnet 7. The core structure includes an upper magnetostrictive sheet 1, an upper electrode 2, a piezoelectric layer 3, a lower electrode 4, and a lower magnetostrictive sheet 5. In addition to providing clamping capability, the upper magnet 6 and the lower magnet 7 can also provide a bias magnetic field, improve the magnetoelectric coupling coefficient, and improve stress transmission efficiency, thereby enhancing the radiation signal.

[0039] The upper magnetostrictive sheet 1, upper electrode 2, piezoelectric layer 3, lower electrode 4, and lower magnetostrictive sheet 5 have the same width. The upper electrode 2 completely covers the upper surface of the piezoelectric layer 3, and the lower electrode 4 completely covers the lower surface of the piezoelectric layer 3. The lengths of the upper magnetostrictive sheet 1 and the lower magnetostrictive sheet 5 are greater than the lengths of the upper electrode 2, the piezoelectric layer 3, and the lower electrode 4. The number of upper magnets 6 and lower magnets 7 can be one or more. When there is only one upper magnet and one lower magnet 7, the lengths and widths of the upper magnet 6, the lower magnet 7, and the piezoelectric layer 3 are the same, and the geometric centers of the upper magnet 6, the lower magnet 7, the upper magnetostrictive sheet 1, the upper electrode 2, the piezoelectric layer 3, the lower electrode 4, and the lower magnetostrictive sheet 5 are located on the same vertical line.

[0040] When there are multiple upper magnets 6 and multiple lower magnets 7, the width of the upper magnets 6 and the lower magnets 7 is the same as the width of the piezoelectric layer 3, and the two side edges of the multiple upper magnets 6 arranged side by side are flush with the two side edges of the piezoelectric layer 3, and the two side edges of the multiple lower magnets 7 arranged side by side are also flush with the two side edges of the piezoelectric layer 3; the geometric center formed by the multiple upper magnets 6 and the geometric center formed by the multiple lower magnets 7 are also located on the same vertical line as the geometric center of the piezoelectric layer 3.

[0041] Furthermore, the polarization direction of the upper magnetostrictive sheet 1 and the lower magnetostrictive sheet 5 is horizontal, and the polarization direction of the piezoelectric layer 3 is the thickness direction, that is, the C-axis direction.

[0042] Both the upper electrode 2 and the lower electrode 4 are interdigitated electrodes, and the interdigitated electrodes are tightly bonded to the piezoelectric layer 3. To ensure the shape retention of the interdigitated electrode structure of the upper electrode 2 and the lower electrode 4, the interdigitated electrodes are printed on the PI substrate, and the specific dimensional parameters of the interdigitated electrodes are shown in the attached figure. Figure 2 As shown. The excitation signal is input through the interdigitated electrodes, which excites the piezoelectric layer 3 to vibrate and generate sound waves; at the same time, the vibration of the piezoelectric layer 3 is conducted to the magnetostrictive sheet (including the upper magnetostrictive sheet 1 and the lower magnetostrictive sheet 5), and the magnetostrictive sheet vibrates to radiate electromagnetic waves.

[0043] Preferably, the material of the piezoelectric layer 3 is one or more of AlN, ZnO, PZT, LiNbO3, LiTaO3 and their doped products (the doped products here refer to the doped products of any one of AlN, ZnO, PZT, LiNbO3 and LiTaO3).

[0044] Preferably, the materials of the upper electrode 2 and the lower electrode 4 are Au, Cu, and copper; and the thickness of both the upper electrode 2 and the lower electrode 4 is 20um to 100um.

[0045] Preferably, both the upper magnet 6 and the lower magnet 7 are made of neodymium iron boron.

[0046] The working principle of the electromagnetic-acoustic radiator in this invention is as follows: An external AC excitation voltage is applied to the piezoelectric layer 3 through the upper electrode 2 and the lower electrode 4. The piezoelectric layer 3 vibrates due to the piezoelectric effect. This vibration is transmitted to the upper magnetostrictive sheet 1 and the lower magnetostrictive sheet 5, causing the upper magnetostrictive sheet 1 and the lower magnetostrictive sheet 5 to oscillate and radiate electromagnetic wave signals. These electromagnetic wave signals are in the same frequency as the excitation voltage. Simultaneously, the mechanical vibration of the piezoelectric layer 3 itself drives the air to vibrate, exciting the radiation of sound waves at the same frequency.

[0047] Because the electromagnetic-acoustic radiator in this invention has both electromagnetic and acoustic operating modes, it can determine the communication distance by the degree of electromagnetic wave attenuation in emergency communication conditions such as cross-domain communication, and improve the detection rate of weak communication information by using acoustic signals and electromagnetic signals. The electromagnetic signal and acoustic signal operate at the same frequency, and by adjusting the dimensions of the piezoelectric layer 3, the upper magnetostrictive sheet 1, and the lower magnetostrictive sheet 5, electromagnetic-acoustic signal radiation in the range of 3kHz-100kHz can be achieved.

[0048] Example 2:

[0049] Example 2 provides a method for fabricating a low-frequency miniaturized electromagnetic-acoustic radiator as described in Example 1, specifically including the following steps:

[0050] S1: Material preparation;

[0051] Specifically, a 30mm*10mm*0.2mm C-axis polarized PZT-5A piezoelectric sheet is cut as piezoelectric layer 3;

[0052] Cut two Terfenol-D magnetostrictive sheets with dimensions of 80mm*10mm*0.2mm, and use them as the upper magnetostrictive sheet 1 and the lower magnetostrictive sheet 5, respectively.

[0053] Prepare a pair of interdigital electrodes on a PI substrate. The electrode strips are 500µm wide and 500µm apart. There are 16 pairs of electrodes. The copper electrode is 20µm thick. The total effective width of the interdigital electrodes is 10mm and the effective length is 30mm. They are printed on one side of the PI substrate and serve as the upper electrode 2 and the lower electrode 4, respectively.

[0054] Prepare two magnet blocks, each 30mm*10mm*2mm, to be used as the upper magnet 6 and the lower magnet 7 respectively.

[0055] S2: The upper electrode 2 and the lower electrode 4 are respectively bonded and fixed to the top and bottom of the piezoelectric layer 3;

[0056] Specifically, the piezoelectric element and two PI substrate interdigitated electrodes are bonded together. With the printed electrode side of one PI substrate interdigitated electrode facing upwards, a 1:1 mixture of epoxy resin and AB adhesive is applied evenly. The piezoelectric element is placed in the center of the interdigitated electrode, and epoxy resin adhesive is applied to the top of the piezoelectric element. The printed electrode side of the other PI substrate interdigitated electrode is then bonded to the piezoelectric element with its printed electrode side facing downwards. Appropriate pressure is applied on the bonding machine to ensure good adhesion between the PI substrate and the piezoelectric element. The bonding is allowed to stand for 3 hours to allow the epoxy resin adhesive to fully cure.

[0057] S3: The upper magnetostrictive sheet 1 is bonded and fixed to the top of the upper electrode 2, and the lower magnetostrictive sheet 5 is bonded and fixed to the bottom of the lower electrode 4.

[0058] Specifically, the structure bonded in step S2 is taken out of the bonding machine, and a Terfenol-D magnetostrictive sheet is bonded to the non-printed electrode surface of the interdigitated electrode of the PI substrate on both sides of the piezoelectric sheet. Pressure is applied, and the sheet is left to stand for complete curing.

[0059] S4: Clamp and fix the upper magnet 6 and the lower magnet 7 to the outside of the upper magnetostrictive sheet 1 and the lower magnetostrictive sheet 5 respectively;

[0060] S5: Solder leads to the upper electrode 2 and the lower electrode 4 respectively to bring out the circuit interface;

[0061] Specifically, a magnet is clamped between the middle sections of both sides of the piezoelectric sheet-interdigital electrode-magnetostrictive sheet composite structure. Then, wires are soldered onto the interdigital electrodes to lead out the circuit interface.

[0062] When transmitting a signal, the upper electrode 2 and the lower electrode 4 excite surface waves, causing the piezoelectric layer 3 to vibrate. This vibration is transmitted to the upper magnetostrictive sheet 1 and the lower magnetostrictive sheet 5. On one hand, the vibration of the piezoelectric layer 3 radiates sound waves, such as... Figure 3 As shown; on the other hand, the vibration radiation of the upper magnetostrictive plate 1 and the lower magnetostrictive plate 5 emits electromagnetic waves, as shown in the attached diagram. Figure 4 As shown, the radiator achieves electromagnetic-acoustic dual-mode signal radiation. The upper magnet 6 and the lower magnet 7 serve to improve interlayer stress transfer efficiency and enhance the electromagnetic-acoustic radiation signal.

[0063] It should be noted that the operating frequency of the magnetoelectric antenna in this embodiment is 3kHz to 100kHz, at which the electromagnetic wavelength is 3000 to 10000m. The antenna dimensions of this embodiment are 80mm*10mm*5mm, which is at least five orders of magnitude smaller than that of a traditional electric resonant antenna.

[0064] Furthermore, the invention also verified the ability of the electromagnetic-acoustic radiator to emit electromagnetic waves. The test method involved using a signal generator to produce a standard 44.75kHz sine wave signal, applying it to the radiator, and receiving the electromagnetic wave signal at a distance of 50cm using a receiving coil. The signal was then characterized using an oscilloscope. The test results are attached. Figure 5 As shown, from the appendix Figure 5 As can be seen, the radiator can achieve electromagnetic wave radiation with the same frequency as the excitation source signal and can maintain the integrity of the waveform.

[0065] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A low-frequency miniaturized electromagnetic-acoustic radiator, characterized in that: From top to bottom, it includes an upper magnetostrictive sheet, an upper electrode, a piezoelectric layer, a lower electrode, and a lower magnetostrictive sheet. The upper magnetostrictive sheet, the upper electrode, the piezoelectric layer, the lower electrode, and the lower magnetostrictive sheet have the same width, their geometric centers are located on the same vertical line, and the lengths of the upper and lower magnetostrictive sheets are greater than the lengths of the upper electrode, the piezoelectric layer, and the lower electrode. The upper magnetostrictive sheet has an upper magnet at its top and the lower magnetostrictive sheet has a lower magnet at its bottom. The geometric centers of the upper and lower magnets are also located on the same vertical line as the centers of the upper and lower magnetostrictive sheets. The polarization direction of the upper and lower magnetostrictive sheets is horizontal, and the polarization direction of the piezoelectric layer is the thickness direction. Both the upper and lower electrodes are interdigitated electrodes, and the interdigitated electrodes are in close contact with the piezoelectric layer.

2. The low-frequency miniaturized electromagnetic-acoustic radiator according to claim 1, characterized in that: The material of the piezoelectric layer is one or more of AlN, ZnO, PZT, LiNbO3, LiTaO3 and their doped products.

3. A low-frequency miniaturized electromagnetic-acoustic radiator according to claim 1, characterized in that: The upper and lower electrodes are made of any one of Au, Cu, or copper; and the thickness of both the upper and lower electrodes is 20µm to 100µm.

4. A low-frequency miniaturized electromagnetic-acoustic radiator according to claim 1, characterized in that: Both the upper and lower magnets are made of neodymium iron boron.

5. A method for fabricating a low-frequency miniaturized electromagnetic-acoustic radiator as described in any one of claims 1-4, characterized in that, Includes the following steps, S1: Material preparation; S2: Bond and fix the upper electrode and the lower electrode to the top and bottom of the piezoelectric layer, respectively; S3: The upper magnetostrictive sheet is bonded and fixed to the top of the upper electrode, and the lower magnetostrictive sheet is bonded and fixed to the bottom of the lower electrode. S4: Clamp and fix the upper magnet and the lower magnet to the outside of the upper magnetostrictive sheet and the lower magnetostrictive sheet respectively; S5: Solder leads to the upper and lower electrodes respectively to bring out the circuit interface.

6. The method for fabricating a low-frequency miniaturized electromagnetic-acoustic radiator according to claim 5, characterized in that, Step S1 includes the following steps: S101: Cut a C-axis polarized piezoelectric sheet to serve as a piezoelectric layer; S102: Cut two magnetostrictive sheets of the same size, which will be used as the upper magnetostrictive sheet and the lower magnetostrictive sheet, respectively. S103: Prepare a pair of PI substrate interdigitated electrodes, which will be used as the upper and lower layer electrodes, respectively. S104: Prepare magnet blocks, which will be used as the upper and lower layer magnets respectively.

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