A composite rod magneto-electro-mechanical antenna and its fabrication method

Abstract

This invention proposes a composite rod-type magneto-electro-mechanical antenna and its fabrication method, belonging to the field of mechanical antenna technology. It solves the problems of low power capacity, weak radiation capability, and short communication distance commonly found in existing magneto-electro-mechanical antennas. It comprises a magnetostrictive layer, two transition layers, two sets of driving layers, and two sets of tail mass blocks. The magnetostrictive layer is located at the center, with the transition layer, driving layer, and tail mass blocks arranged sequentially from the center to both ends on either side. Each driving layer is composed of multiple piezoelectric ceramic rings and multiple electrode sheets stacked alternately. Each tail mass block consists of mass block one, a disc spring, and mass block two connected sequentially. The length of this composite rod-type magneto-electro-mechanical antenna is comparable to that of a traditional three-layer magneto-electro-electric antenna. When the antenna adopts the first-order longitudinal mode, it can operate in the very low frequency band. Depending on different application requirements, the composite rod-type magneto-electro-mechanical antenna of this invention can adopt the second-order longitudinal mode or operate in other frequency bands.

Description

Technical Field

[0001] This invention belongs to the field of mechanical antenna technology, and in particular relates to a composite rod magneto-electro-mechanical antenna and its fabrication method. Background Technology

[0002] To achieve information exchange in lossy media and cross-domain environments, the development of high-efficiency, miniaturized low-frequency communication antennas has become a research hotspot and challenge. Traditional radio frequency dipole antennas rely on the accelerated motion of electrons in conductors to generate time-varying electromagnetic fields. Their radiation efficiency is constrained by their physical size, making it impossible to simultaneously meet the application requirements of high efficiency and portability.

[0003] From the perspective of breaking through traditional antenna design concepts, in 2018, the U.S. Defense Advanced Research Projects Agency (DARPA) first announced the research program for mechanical antennas (AMEBA). Mechanical antennas propagate information by controlling the mechanical movement of electric or magnetic dipoles to establish time-varying electric or magnetic fields in space. Among the four typical mechanical antenna design methods, macroscopically rotating electrets or permanent magnets cannot achieve relatively high-frequency radiation fields, and the requirements for drive motors during information modulation are high, resulting in significant difficulties in information loading. On the other hand, microscopically dynamically modulating electric dipoles in piezoelectric materials or magnetic dipoles in soft magnetic materials makes it easier to achieve higher radiation efficiency and information bandwidth. Among these, dipole oscillating mechanical antennas based on magnetoelectric coupling combine the high efficiency of piezoelectric drive with the controllability of dipole modulation, forming a key foundation for the development of very low frequency (VLF) communication technology. For the same size, the radiation performance of magnetoelectric mechanical antennas is several orders of magnitude higher than that of traditional electrically small antennas.

[0004] However, existing magneto-electric mechanical antennas generally suffer from prominent problems such as small power capacity, weak radiation capability, and short communication distance, making them difficult to realize communication applications. The reasons behind this are mainly as follows: 1) Traditional magneto-electric resonators have a high mechanical quality factor and low resonant impedance, making it difficult to support high driving electric fields and narrow bandwidth; 2) Layered composite magneto-electric materials have small piezoelectric phase volume and weak magnetic moment; 3) Piezoelectric materials, especially piezoelectric single crystals, have low Curie temperatures and insufficient performance under strong field driving. Summary of the Invention

[0005] In view of this, the present invention aims to propose a composite rod magneto-mechanical antenna and its fabrication method, which is a composite rod low-frequency magneto-mechanical antenna operating in longitudinal vibration mode and its fabrication method, in order to solve the prominent problems of small power capacity, weak radiation capability and short communication distance that exist in existing magneto-mechanical antennas.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a composite rod magneto-electro-mechanical antenna and its fabrication method, comprising a magnetostrictive layer, two transition layers, two sets of driving layers and two sets of tail mass blocks. The magnetostrictive layer is located at the center, and the transition layer, driving layer and tail mass block are arranged sequentially from the center to both ends on both sides. Each set of driving layers is formed by alternating stacking of multiple piezoelectric ceramic rings and multiple electrode sheets. Each set of tail mass blocks is formed by sequentially connecting mass block one, disc spring and mass block two.

[0007] Furthermore, the magnetostrictive layer is disposed at the node position of the first-order longitudinal vibration mode of the composite rod antenna.

[0008] Furthermore, the magnetostrictive layer is composed of multiple layers of soft magnetic bulk material or soft magnetic magnetic material, and the magnetostrictive material is one of Metglas, Fe-Ga alloy, Terfernol-D alloy, Fe-Ni alloy, FeCo, FeCoB, FeGaB, NiZn ferrite and Ni metal.

[0009] Furthermore, the transition layer and the magnetostrictive layer are connected by epoxy resin, and the material of the transition layer is metal or alloy.

[0010] Furthermore, each piezoelectric ceramic ring is polarized along its thickness and is electrically connected in parallel between adjacent rings.

[0011] Furthermore, the piezoelectric material of the piezoelectric ceramic ring includes piezoelectric ceramics and piezoelectric single crystals, and is one of LiNbO3, BaTiO3, Pb(Zr,Ti)O3, Pb(Mg,Nb)O3-PbTiO3, Pb(Zn,Nb)O3-PbTiO3, or BiScO3-PbTiO3.

[0012] Furthermore, the magnetostrictive layer, two transition layers, two sets of driving layers, and two sets of tail mass blocks are cylinders with the same radius and height and a central through hole. Then, each component is bonded and stacked sequentially along the axial direction. Finally, they are assembled by prestressed bolts through the central through hole and prestress is applied. The final assembled antenna is a perfectly symmetrical cylindrical rod in three dimensions.

[0013] Furthermore, the tail mass block two is cylindrical or trumpet-shaped.

[0014] A composite rod magneto-electro-mechanical antenna specifically includes the following steps:

[0015] (1) Antenna structure design and simulation verification;

[0016] (2) Material processing and fixture preparation;

[0017] (3) Fabrication of the driving layer;

[0018] (4) Bond the transition layer, tail mass block and drive layer together;

[0019] (5) The magnetostrictive layer in the middle is bonded to the composite structure at both ends to obtain the antenna body.

[0020] (6) Use prestressed bolts to assemble the disc spring, the two tail mass blocks and the antenna body obtained above to obtain the antenna prototype before the prestress is applied.

[0021] (7) Apply bolt prestress to obtain the final composite rod antenna prototype.

[0022] Compared with the prior art, the beneficial effects of the composite rod magneto-electro-mechanical antenna and its fabrication method described in this invention are:

[0023] (1) The composite rod magneto-electro-mechanical antenna of the present invention has a length comparable to that of a traditional three-layer magneto-electro-electric antenna. When the antenna adopts the first-order longitudinal mode, it can operate in the very low frequency band. At the same time, this antenna structure can also adopt the second-order longitudinal mode and operate in other frequency bands, with the advantages of strong frequency selectivity and large bandwidth.

[0024] (2) The driving source of the composite rod magneto-electro-mechanical antenna described in this invention is a stack of multiple piezoelectric sheets, which provides a greater driving force for the magnetostrictive material. More importantly, the piezoelectric stack can greatly improve the power capacity of the antenna.

[0025] (4) The radiation source of the composite rod magneto-electro-mechanical antenna described in this invention uses a larger volume magnetostrictive material, which can greatly improve the radiation capability of the antenna, thereby solving the problem of short communication distance of current mechanical antennas. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 This is a schematic diagram of the composite rod magneto-electro-mechanical antenna described in this invention;

[0028] Figure 2 This is a schematic diagram showing the dimensions of a specific embodiment of the composite rod magneto-electro-mechanical antenna described in this invention;

[0029] Figure 3 The simulation results of COMSOL in a specific embodiment of the present invention are shown, including the first-order longitudinal vibration mode and its characteristic frequency.

[0030] Figure 4The simulation results of COMSOL in a specific embodiment of the present invention are shown, including the second-order longitudinal vibration mode and its characteristic frequency.

[0031] Figure 5 This is a second specific embodiment of the present invention for reducing the resonant frequency and its structural design method;

[0032] Figure 6 The image shows the COMSOL simulation results of a specific embodiment of the present invention for reducing the resonant frequency, including the first-order longitudinal vibration mode and its characteristic frequency.

[0033] Figure 7 The image shows the COMSOL simulation results of a specific embodiment of the present invention for reducing the resonant frequency, including the second-order longitudinal vibration mode and its characteristic frequency.

[0034] Figure 8 This is a specific embodiment three of the present invention, which takes into account the stress amplification at the node position, and its structural design method;

[0035] Figure 9 The COMSOL simulation results of a specific embodiment three of the present invention are shown, including the first-order longitudinal vibration mode and its characteristic frequency;

[0036] Figure 10 The diagram shows the COMSOL simulation results of a specific embodiment three of the present invention, including the second-order longitudinal vibration mode and its characteristic frequency.

[0037] In the diagram: 1-Double-ended stud, 2-Nut, 3-Magnetostrictive layer, 4-Transition layer, 5-Piezoelectric ceramic ring, 6-Electrode sheet, 7-Mass block one, 8-Disc spring, 9-Mass block two. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0039] like Figure 1 As shown, a composite rod-type magneto-electro-mechanical antenna includes a magnetostrictive layer 3, two transition layers 4, two sets of driving layers, and two sets of tail mass blocks. The magnetostrictive layer 3 is located at the center, and the transition layers 4, driving layers, and tail mass blocks are arranged sequentially from the center to both ends on both sides. Each set of driving layers is formed by alternating stacking of multiple piezoelectric ceramic rings 5 ​​and multiple electrode sheets 6. Each set of tail mass blocks is formed by sequentially connecting mass block 1 7, disc spring 8, and mass block 2 9.

[0040] The magnetostrictive layer 3 is disposed at the nodal position of the first-order longitudinal vibration mode of the composite rod antenna. The magnetostrictive layer 3 can be composed of multiple layers of soft magnetic bulk material or soft magnetic magnetic material. The magnetostrictive material can be one of Metglas, Fe-Ga alloy, Terfernol-D alloy, Fe-Ni alloy, FeCo, FeCoB, FeGaB, NiZn ferrite, and Ni metal. Depending on the specific embodiment, the shape and size of the magnetostrictive layer 3 can also be changed accordingly.

[0041] The magnetostrictive layer 3 is flanked by acoustic impedance matching transition layers 4. The transition layers 4 and the magnetostrictive layer 3 are connected by epoxy resin. The material of the transition layer 4 can be metal or alloy, depending on the materials of the magnetostrictive layers 3 and the piezoelectric ceramic rings 5 ​​at both ends. Depending on the specific embodiment, the shape and size of the transition layer 4 can also be changed accordingly.

[0042] The piezoelectric material of the piezoelectric ceramic ring 5 includes piezoelectric ceramics and piezoelectric single crystals, and can be one of LiNbO3, BaTiO3, Pb(ZrTi)O3, Pb(Mg,Nb)O3-PbTiO3, Pb(Zn,Nb)O3-PbTiO3, or BiScO3-PbTiO3. Each piezoelectric sheet is thickness-polarized and adopts an electrically parallel structure. Each piezoelectric sheet is bonded to each electrode sheet with epoxy resin adhesive. According to specific embodiments, the shape, size, and number of stacked sheets of the piezoelectric stack can also be changed accordingly.

[0043] The free end of the composite rod antenna is augmented with a tail mass. The tail mass consists of two layers: mass block 7 and mass block 9, connected by a disc spring 8. Mass block 7, located near the drive layer, is bonded to the drive layer with epoxy resin. The tail mass can be made of a high-density, high-hardness metal or alloy.

[0044] The functional layers of the composite rod magneto-electro-mechanical antenna are connected by bolts, and prestress is applied by nuts on both sides in conjunction with disc springs.

[0045] Implementation Case 1:

[0046] refer to Figure 1 This invention proposes a composite rod-type magneto-electro-mechanical antenna with longitudinal vibration mode, comprising a double-ended stud 1, a fixing nut 2, a magnetostrictive layer 3, a transition metal layer 4, a piezoelectric stack (driving layer), and a tail mass. The piezoelectric stack consists of piezoelectric ceramic rings 5 ​​and matching electrode sheets 6. Two identical piezoelectric stacks are formed by stacking and bonding eight piezoelectric ceramic rings and nine electrode sheets. Each piezoelectric ceramic ring 5 is polarized along its thickness direction, and adjacent rings are electrically connected in parallel. The tail mass consists of mass block 7, a disc spring 8, and mass block 9.

[0047] The main components of the composite rod antenna, from the center outwards, are, in sequence, a magnetostrictive layer 3, a transition layer 4, a driving layer, a tail mass block, and a fixing nut. Each component is a cylinder with the same radius and height, and a through hole in the center. The components are then bonded and stacked sequentially along the axial direction. Finally, they are assembled by prestressed bolts through the central through hole and prestress is applied. The final assembled antenna is a perfectly symmetrical rod shape in all three dimensions.

[0048] refer to Figure 2 In this embodiment, the specific geometric dimensions of each component can be selected as follows: Since the antenna is basically cylindrical, all components except the prestressed bolts and disc springs are cylinders with the same radius but different heights, and each has a through hole with a radius of 4mm at its center. The magnetostrictive layer is 30mm long, the transition layer is 5mm long, each of the two piezoelectric stacks contains 8 piezoelectric plates and 9 electrode plates, each piezoelectric plate is 2mm thick, the electrode plates are 0.1mm thick, the overall piezoelectric stack is approximately 17mm thick, the first mass block is 3mm thick and has a groove for fixing the disc spring on the contact side, and the second tail mass block is 5mm thick. The radius of the double-ended stud in the prestressed bolt is 3.5mm, and the nut and disc spring can be selected from corresponding standard parts.

[0049] In this embodiment, when the composite rod magneto-electromechanical antenna is in operation, an alternating electric field is provided to the piezoelectric stacks on both sides through the positive and negative electrode leads in the piezoelectric stack driving layer 5. The two piezoelectric stack driving layers 5 will simultaneously undergo longitudinal expansion and contraction vibrations. Due to the action of the prestressed bolts, the driving force generated by the piezoelectric stack driving layer 5 will be transmitted to the intermediate magnetostrictive layer 3 to the maximum extent through the transition layer 4. The magnetic domains in the magnetostrictive material will move or flip, thereby radiating an electromagnetic field outward. When the frequency of the alternating electric field reaches the first (or second) longitudinal vibration frequency of the composite rod antenna, the antenna will produce its maximum output. Simultaneously, a DC bias magnetic field of a certain strength needs to be provided during antenna operation, with its direction along the antenna axis and its magnitude determined by the material of the magnetostrictive layer.

[0050] Figure 3-4 The COMSOL simulation results for this implementation method are simplified as necessary, but this does not affect the reliability of the model solution. Figure 3 The first-order longitudinal vibration mode and its characteristic frequency of the composite rod antenna. Figure 4 The second-order longitudinal vibration mode and its characteristic frequency of the composite rod antenna are given.

[0051] Implementation Case 2:

[0052] refer to Figure 5 This is the second embodiment proposed in this invention. Combined with... Figure 1The difference between Embodiment 1 and Embodiment 2 lies in the geometry and size of the tail mass block 9. The tail mass block 9 is horn-shaped, while the other corresponding components are the same as in Embodiment 1. The main purpose of this embodiment is to reduce the resonant frequency of the antenna. Its frequency reduction principle is as follows:

[0053] For a rod operating in a first-order longitudinal vibration mode, the displacement distribution function is expressed as: in The displacement distribution function is approximated as: In the formula, Δ represents the displacement amplitude of the free end. Using the lumped mass method for system equivalence, the equivalent mass of the variable cross-section rod can be written as:

[0054]

[0055] For a rod with a uniform cross-section, the stiffness is... Consider a variable cross-section rod, which can be simplified to an infinite number of small, uniform cross-section rods connected in series. According to the formula for the stiffness of a series spring, the stiffness of the system can be written as:

[0056]

[0057] Therefore, the resonant frequency ω of the variable cross-section rod can be expressed as:

[0058]

[0059] In the above formula, the molecule This can be viewed as a weighting function, where the mass at the center of the rod contributes zero to the system's kinetic energy, having the smallest weight, while the free end has the largest weight. Considering this, increasing the cross-sectional area of ​​the free end of the rod will effectively increase the kinetic energy in the numerator of the above equation, while the weighting function in the denominator is 1, indicating that it is not sensitive to the cross-sectional area distribution.

[0060] Figure 6-7 The COMSOL simulation results for implementation method two are shown below. Figure 6 The first-order longitudinal vibration mode and its characteristic frequency are described in Embodiment 2 of the composite rod magneto-electro-mechanical antenna. Figure 7 This refers to the second-order longitudinal vibration mode and its characteristic frequency. Combined with... Figure 3-4 Compared to Implementation Method 1, the antenna resonant frequency decreased from 15.741kHz in the first order to 10.246kHz, and from 42.046kHz to 39.039kHz in the second order. Simulation results show that frequency reduction can be achieved simply by increasing the mass of the two end mass blocks 9, basically realizing the expected goals and design requirements of this implementation method.

[0061] Implementation Case 3:

[0062] refer to Figure 8 This is the third embodiment proposed in this invention. Combined with... Figure 1 The main difference between Embodiment 1 and Embodiment 3 lies in the geometry and size of the intermediate magnetostrictive layer 3, whose diameter is smaller than that of the transition layer 4. However, the diameters of the transition layer 4, the driving layer, and the mass block 7 are the same. The main purpose of this embodiment is to achieve stress amplification and resonant frequency reduction in the magnetostrictive layer, with the frequency reduction principle being the same as in Embodiment 2. Furthermore, in this invention, other components of the antenna can also be selected with different sizes and geometries; they are not completely fixed. The only certainty is the structural composition of the antenna—the structural characteristics of the mass block-piezoelectric stack-magnetostrictive layer-piezoelectric stack-mass block connected by prestressed bolts.

[0063] Figure 9-10 The COMSOL simulation results for implementation method three are shown below. Figure 9 The first-order longitudinal vibration mode and its characteristic frequency are described in Embodiment 3 of the composite rod magneto-electro-mechanical antenna. Figure 10 This refers to the second-order longitudinal vibration mode and its characteristic frequency. Combined with... Figure 3-4 Compared to Implementation Method 1, the first-order resonant frequency of the antenna drops to 13.804 kHz due to the reduced mass of the magnetostrictive layer in the middle, while the second-order resonant frequency remains essentially unchanged. The three simulation results demonstrate that the antenna resonant frequency can be optimized by adjusting the mass ratio, shape, and size of each component in the antenna, as well as the overall antenna dimensions, providing some guidance for antenna structure optimization design.

[0064] In this embodiment, the overall structure of the composite rod antenna is completely symmetrical and can be divided into four main parts: the middle magnetostrictive layer 3, the three-layer composite at both ends (transition layer 4 - piezoelectric stacked driving layer - tail mass block 7), and prestressed bolts.

[0065] Based on the structural characteristics of composite rod antennas, the specific fabrication process of the composite rod antenna described in this invention can be summarized as follows:

[0066] I. Antenna structure design and simulation verification;

[0067] II. Material processing and fixture preparation;

[0068] III. Fabrication of the piezoelectric stack driving layer;

[0069] IV. Bond the transition layer 4, the tail mass block, and the piezoelectric stacked drive layer together.

[0070] 5. The antenna body is obtained by bonding the middle magnetostrictive layer 3 with the three-layer composite structure at both ends.

[0071] 6. Using prestressed bolts (double-ended bolts 1), assemble the disc spring 8, the two tail mass blocks 9, and the antenna body obtained above to obtain the antenna prototype before applying prestress.

[0072] 7. Apply bolt prestress to obtain the final composite rod antenna prototype.

[0073] In step three, the fabrication of the piezoelectric stack driving layer is specifically carried out as follows:

[0074] (1) Take 8 piezoelectric ceramic rings 5 ​​with thickness polarization and marked positive and negative poles and 9 copper electrode sheets 6, clean them ultrasonically and dry them in a vacuum drying oven for later use.

[0075] (2) Take one electrode sheet 6 and one piezoelectric ceramic ring 5 at a time, coat one side of each with a uniform thickness of epoxy resin adhesive, and then stack them layer by layer.

[0076] (3) Fix the piezoelectric stack with a V-shaped clamp and apply pressure axially with a weight, then cure at room temperature for 24 hours.

[0077] (4) The preparation process of the second piezoelectric stack is exactly the same as the above steps.

[0078] In step four, the transition layer 4, the tail mass block, and the piezoelectric stack drive layer are bonded together. The specific operation is as follows:

[0079] (1) Take the processed metal transition layer 4, the tail mass block and two flexible insulating films, clean them ultrasonically and dry them for later use. The function of the flexible insulating film is to ensure the insulating connection between the metal transition layer 4 and the piezoelectric stacked driving layer.

[0080] (2) Apply epoxy resin evenly to the metal transition layer 4, the tail mass block and the piezoelectric stack drive layer, fix the piezoelectric stack with a V-shaped clamp and apply pressure through a weight in the axial direction, and cure at room temperature for 24 hours.

[0081] In step five, the magnetostrictive layer 3 is bonded to the three-layer composite structure on both sides to obtain the antenna body. The specific operation is as follows:

[0082] (1) Take the processed magnetostrictive layer 3 and the two three-layer composite structures obtained in the above two steps, wipe the bonding surface with alcohol and then dry it in a vacuum drying oven for later use.

[0083] (2) Apply epoxy resin evenly to the bonding surfaces of the magnetostrictive layer 3 and the two three-layer composite structures respectively, and stack them together in sequence;

[0084] (3) Fix it with a V-shaped clamp and apply pressure axially with a heavy object, and cure at room temperature for 24 hours.

[0085] In step six, the assembly and prestressing of the composite rod antenna are carried out as follows:

[0086] (1) Take two tail mass blocks, one double-ended stud 1, two washers, four disc springs 8 and four nuts prepared for use. Among them, the washers, studs, nuts and disc springs 8 can be standard parts;

[0087] (2) Using double-ended studs 1, assemble the composite rod antenna in the following order: tail mass block 2 9 - disc spring 8 - antenna body - disc spring 8 - tail mass block 2 9. Then, use washers and nuts to fix it on both sides of the double-ended studs 1. During the assembly process, try to keep the central axis of each antenna component aligned and symmetrical in the axial direction to prevent the studs from contacting the inner wall of the through hole, which would affect the working state of the antenna.

[0088] (3) Install the composite rod antenna vibrator obtained in the previous step together with the force-applying fixture on the table. The fixture is divided into two identical upper and lower parts, with a circular slot in the center for mounting and positioning the antenna, and four through holes. Then, the fixture and the antenna are fixed to the table together by four lead screws. Two of the four lead screws are used for fixing, and the other two are used to suspend weights to apply prestress.

[0089] (4) Install load-bearing rods on the two lead screws used to suspend the weight and suspend weights on them. Determine the magnitude of the prestress by increasing or decreasing the mass of the weights. The principle of applying prestress is to cause the antenna to contract and deform along the axis by suspending the weight. At this time, simply tighten the nut appropriately and then remove the suspended weight. The prestress of the antenna has been applied. After removing the clamp, the final antenna prototype is obtained.

[0090] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A composite rod-type magneto-electro-mechanical antenna, characterized in that: It includes a magnetostrictive layer (3), two transition layers (4), two sets of driving layers and two sets of tail mass blocks. The magnetostrictive layer (3) is located at the center, and the transition layer (4), driving layer and tail mass block are arranged sequentially from the center to both ends on both sides. Each set of driving layers is formed by alternating stacking of multiple piezoelectric ceramic rings (5) and multiple electrode plates (6). Each set of tail mass blocks is formed by sequentially connecting mass block one (7), disc spring (8) and mass block two (9). The magnetostrictive layer (3), two transition layers (4), multiple piezoelectric ceramic rings (5), multiple electrode sheets (6) and mass block 1 (7) are cylinders with the same radius and a through hole in the center. Then, each component is bonded and stacked in sequence along the axial direction. Finally, it is assembled by prestressed bolts through the central through hole and prestress is applied. The antenna after final assembly is a circular rod that is completely symmetrical in three dimensions. Each piezoelectric ceramic ring (5) is polarized along the thickness direction and is electrically connected in parallel between adjacent rings; The magnetostrictive layer (3) is disposed at the node position of the first longitudinal vibration mode of the composite rod antenna.

2. The composite rod magneto-electro-mechanical antenna according to claim 1, characterized in that: The magnetostrictive layer (3) is composed of soft magnetic bulk material or multiple layers of soft magnetic magnetic material. 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.

3. The composite rod magneto-electro-mechanical antenna according to claim 1, characterized in that: The transition layer (4) and the magnetostrictive layer (3) are connected by epoxy resin, and the material of the transition layer (4) is metal or alloy.

4. The composite rod magneto-electro-mechanical antenna according to claim 1, characterized in that: The piezoelectric material of the piezoelectric ceramic ring (5) includes piezoelectric ceramics and piezoelectric single crystals. The piezoelectric material is one of LiNbO3, BaTiO3, Pb(Zr,Ti)O3, Pb(Mg,Nb)O3-PbTiO3, Pb(Zn,Nb)O3-PbTiO3 or BiScO3-PbTiO3.

5. The composite rod magneto-electro-mechanical antenna according to claim 1, characterized in that: The tail mass block 2 (9) is cylindrical or trumpet-shaped.

6. The composite rod magneto-electro-mechanical antenna according to claim 1, characterized in that: The diameter of the magnetostrictive layer (3) is smaller than that of the transition layer (4), but the diameters of the transition layer (4), the driving layer and the mass block (7) are the same.

7. A method for fabricating a composite rod magneto-electro-mechanical antenna as described in any one of claims 1-6, characterized in that: Specifically, the following steps are included: (1) Antenna structure design and simulation verification; (2) Material processing and fixture preparation; (3) Fabrication of the driving layer; (4) Bond the transition layer (4), the tail mass block and the driving layer together; (5) The magnetostrictive layer (3) in the middle is bonded to the composite structure at both ends to obtain the antenna body; (6) Use prestressed bolts to assemble the disc spring (8), two tail mass blocks (9) and the antenna body to obtain the antenna prototype before the prestress is applied. (7) Apply bolt prestress to obtain the final composite rod antenna prototype.

Images