Multi-field driving positive feedback very-low-frequency magnetoelectric antenna array

Abstract

The invention relates to a multi-field driven positive feedback very-low frequency magnetoelectric antenna array, which is composed of a plurality of strong hysteresis piezomagnetic layer / special-shaped high-permeability piezomagnetic film / piezoelectric layer unit arrays, a grid-shaped substrate and magnetically shielded permanent magnet units, on one hand, the strong coupling characteristic of an elastic field / magnetic field between array units is achieved through elastic standing waves generated by the piezoelectric array in the elastic substrate and the magnetic field convergence effect of the special-shaped high-permeability piezomagnetic thin strip, magnetic moment oscillation of the piezomagnetic thin strip is driven, and nonlinear increase of emission field intensity along with the number of the units is achieved; the defect of weak magnetic moment regulation and control energy of a single magnetoelectric antenna and a single elastic field is overcome, and the magnetic field emission efficiency is remarkably improved. And on the other hand, by utilizing a positive feedback magnetic field excitation mechanism between the magnetoelectric transmitting antenna and the magnetic shielding permanent magnet, the limitation bottleneck of a high quality factor on the bandwidth of the magnetoelectric antenna is broken through, and the functions of broadband and high transmitting efficiency are realized.

Description

Technical Field

[0001] The present invention relates to a novel very low frequency antenna for special environments such as underground or underwater, and in particular to a multi-field driven positive feedback very low frequency magnetoelectric antenna array with high transmission efficiency and large bandwidth. Background Art

[0002] Radio frequency communication technologies (such as Bluetooth and 5G) are widely used in daily life, but they will suffer from severe path loss in high conductivity environments such as underground or underwater. In contrast, very low frequency (3kHz to 30kHz) communication systems are more suitable for underground or underwater environments due to their larger skin depth. However, in order to achieve sufficiently large radiation efficiency, traditional very low frequency electric antennas will cause problems such as huge antenna size and serious power consumption, which seriously limits the miniaturization and portability of antennas. Compared with traditional electric antennas, mechanical antennas that have emerged in recent years can achieve low-frequency communication in an extremely small volume. Current low-frequency mechanical antennas mainly include rotating permanent magnet antennas driven by external motors and magnetoelectric antennas with self-resonant piezoelectric layers. Among them, magnetoelectric antennas mainly use the magnetic moment oscillation caused by electromechanical resonance, which can reduce the size by 5 orders of magnitude compared with conventional electric antennas, while significantly reducing power consumption.

[0003] J.Xu from Virginia Polytechnic Institute in the United States studied a magnetoelectric antenna with a magnetostrictive layer / piezoelectric layer / magnetostrictive layer structure. The radiation efficiency of this antenna is improved by 4 orders of magnitude compared to the electric small loop antenna. N.Sun from Northeastern University studied a conventional magnetoelectric antenna composed of a magnetostrictive film and a piezoelectric plate, which can achieve a communication distance of 100 meters in the air. Y.Niu et al. from Shanghai University of Science and Technology added Rb permanent magnets to the Terfenol-D / PZT magnetoelectric laminate antenna to provide the DC magnetic field bias required for the maximum inverse magnetoelectric effect, which can achieve a communication distance of 2.5m in the air, and the communication distance is increased by 2.27 times compared to the absence of DC bias. However, conventional magnetoelectric antennas still have the following problems: First, conventional magnetoelectric antennas usually require an external permanent magnet to provide the optimal bias magnetic field to achieve a strong radiation magnetic field at the transmitter and high sensitivity at the receiver, but this significantly increases the size and noise of the antenna. At the same time, conventional magnetoelectric antennas usually need to work near the mechanical resonance frequency to significantly improve the inverse magnetoelectric / magnetoelectric effect, but this significantly reduces the bandwidth of the antenna. In addition, the magnetic field transmission efficiency of magnetoelectric antennas is still relatively low, which significantly limits the communication distance.

[0004] The current conventional magnetoelectric antennas are mainly composed of magnetostrictive materials and piezoelectric layers coupled together, and mainly realize the transmission and reception of magnetic fields through the inverse magnetoelectric effect at the transmitting end and the magnetoelectric effect at the receiving end. However, there is a lack of corresponding array technology research, and there are defects such as the need for an external bias magnetic field, narrow bandwidth and weak transmitting magnetic field, which seriously restricts the realization of long-distance and large-bandwidth low-frequency communications. Summary of the invention

[0005] In view of the problems in the background technology, the present invention proposes a multi-field driven positive feedback very low frequency magnetoelectric antenna array with high transmission efficiency and large bandwidth. The magnetoelectric antenna is composed of multiple strong hysteresis pressure magnetic layer / special high permeability piezomagnetic film / piezoelectric layer unit arrays, a grid-shaped substrate and a magnetically shielded permanent magnet unit. The remanent magnetism and magnetostrictive effect of the strong hysteresis pressure magnetic layer provide a built-in bias magnetic field for the high permeability thin strip, and no external magnetic field generating device is required to generate the optimal bias magnetic field. When the transmitting antenna is working, on the one hand, the elastic standing waves of the piezoelectric array in the grid-shaped substrate and the magnetic field convergence effect of the special-shaped high-permeability thin strip are used to realize the strong coupling characteristics of the elastic field / magnetic field between the array units and use them to drive the magnetic moment oscillation of the piezomagnetic thin strip, so as to realize the nonlinear growth of the transmitting field strength with the number of units, overcome the defect of the single magnetoelectric antenna and the single elastic field in regulating the magnetic moment energy weakly, and significantly improve the magnetic field transmission efficiency; on the other hand, the AC magnetic field generated by the magnetoelectric transmitting antenna array is used to regulate the positive feedback magnetic field generated by the magnetic shielding permanent magnet to realize the magnetic field amplification function within a wide bandwidth, break through the bottleneck of the high quality factor on the bandwidth of the magnetoelectric antenna, increase the frequency band and magnetic field transmission efficiency, and realize large bandwidth and long-distance wireless communication functions.

[0006] The technical solution of the present invention is as follows:

[0007] A multi-field driven positive feedback very low frequency magnetoelectric antenna array, characterized in that it comprises a plurality of arrayed magnetoelectric units and a plurality of permanent magnets wrapped by a soft magnetic shielding layer;

[0008] The magnetoelectric unit includes a strong hysteresis piezomagnetic layer, a special-shaped high-permeability piezomagnetic thin strip, a grid-shaped elastic substrate and a piezoelectric layer from top to bottom; the grid-shaped elastic substrates of each magnetoelectric unit are connected in pairs, and the input end of the piezoelectric layer is externally connected to an AC high-voltage source.

[0009] The multi-field driven positive feedback very low frequency magnetoelectric antenna array establishes a built-in magnetic field between the strong hysteresis piezoelectric layer and the shaped high permeability piezomagnetic thin strip, so that the magnetoelectric antenna still has the best performance in the zero bias magnetic field. Under the AC voltage excitation, on the one hand, the AC stress generated by the piezoelectric layer is transmitted to the piezomagnetic layer of the unit to cause the magnetic moment oscillation and thus generate an AC magnetic field; on the other hand, the AC stress generated by the piezoelectric layer is transmitted to the adjacent magnetoelectric unit through the grid-shaped elastic substrate, and the transmission magnetic field of the magnetoelectric unit is enhanced through the elastic field / magnetic field coupling effect of multiple magnetoelectric units. At the same time, the AC magnetic field generated by the magnetoelectric antenna array regulates the magnetic permeability of the soft magnetic shielding layer outside the permanent magnet so that the permanent magnet generates an AC magnetic field, and the AC magnetic field generated by the magnetic shielding permanent magnet is fed back to the shaped high permeability piezomagnetic thin strip of the magnetoelectric antenna array, further enhancing the AC magnetic field generated by the magnetoelectric antenna. Here, the positive feedback mechanism between the magnetoelectric antenna and the magnetic shielding permanent magnet is used to realize the electromagnetic field radiation function with wide bandwidth and high transmission efficiency, thereby improving the wireless communication distance and bandwidth.

[0010] Compared with the prior art, the beneficial technical effects of the present invention are:

[0011] (1) The designed magnetoelectric antenna array realizes the strong coupling effect of elastic field / magnetic field between multiple antenna units, so that the transmission magnetic field intensity of the magnetoelectric antenna array increases nonlinearly with the number of units, overcoming the defect of low magnetic field transmission efficiency of existing single magnetoelectric antennas and significantly increasing the wireless communication distance;

[0012] (2) The high quality factor of the current magnetoelectric antenna, on the one hand, restricts the volume and magnetic moment of the piezomagnetic layer that serves as the mechanical load of the piezoelectric resonator, and on the other hand, also significantly restricts the antenna bandwidth. The low-power positive feedback magnetic field excitation mechanism between the magnetoelectric antenna array and the magnetically shielded permanent magnet proposed in the present invention significantly increases the transmitting magnetic field within a wide bandwidth, breaking the restriction of the gain-bandwidth product of conventional small electric antennas and significantly improving the wireless communication bandwidth and distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The invention relates to a multi-field driven reconfigurable very low frequency magneto-electric transmitting antenna array.

[0014] Figure 2 The invention discloses a variable amplitude double wedge-shaped high magnetic permeability piezomagnetic thin strip.

[0015] Figure 3 This is the grid-shaped elastic substrate of the present invention.

[0016] In the figure: 1—strong hysteresis piezomagnetic layer; 2—special-shaped high magnetic permeability piezomagnetic ribbon; 3—grid-shaped elastic substrate; 4—piezoelectric layer; 5—soft magnetic shielding layer; 6—permanent magnet; 7—AC high voltage source; 8-1—triangular magnetic convergence area of ​​the piezomagnetic ribbon; 8-2—central target area of ​​the piezomagnetic ribbon; 9-1—lower surface of the rectangular node area of ​​the grid-shaped elastic substrate; 9-2—upper surface of the rectangular node area of ​​the grid-shaped elastic substrate. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with specific implementations and drawings, but this should not limit the protection scope of the present invention.

[0018] See also Figure 1 , Figure 1 This is a multi-field driven reconfigurable very low frequency magneto-electric transmitting antenna array of the present invention. As can be seen from the figure, the antenna array includes a strong hysteresis piezomagnetic layer 1, a special-shaped high permeability piezomagnetic thin strip 2, a grid-shaped elastic substrate 3, a piezoelectric layer 4, a soft magnetic shielding layer 5, and a permanent magnet 6. During the antenna transmission process, the piezoelectric layer 4 is excited by an AC high voltage source 7.

[0019] The magnetoelectric antenna is composed of multiple strong hysteresis magnetospheres / special-shaped high permeability magnetosphere films / piezoelectric layers, a grid-shaped substrate and a permanent magnet unit with magnetic shielding.

[0020] Figure 2 The variable amplitude double-wedge high magnetic permeability piezomagnetic thin strip of the present invention comprises four triangular magnetic convergence areas 8-1 and a central target area 8-2. The piezomagnetic thin strip utilizes area 8-1 to converge the transmitting magnetic field generated by the surrounding magnetoelectric units to the central area 8-2, thereby significantly improving the driving ability of the magnetic field on the antenna.

[0021] Figure 3 It is a grid-shaped elastic substrate, in which a piezoelectric resonator array is fixed on the lower surface 9-1 of a plurality of rectangular node regions, and a heterojunction array of a special-shaped high-permeability piezomagnetic thin strip / hysteresis piezomagnetic layer is fixed on the upper surface 9-2.

[0022] The principle of the low-frequency dual-driven magnetoelectric antenna of the present invention is as follows: the transmitting antenna array is composed of a permanent magnet unit wrapped by a hysteresis piezomagnetic layer / special-shaped high-permeability piezomagnetic thin strip / elastic substrate / piezoelectric layer and a soft magnetic thin strip. First, the hysteresis piezomagnetic layer / special-shaped high-permeability piezomagnetic thin strip heterojunction in the antenna unit provides a built-in bias magnetic field and prestress through the non-volatile static magnetoenergy and magnetoelastic energy of the hysteresis piezomagnetic layer, which can reduce the volume of the device and increase the piezomagnetic properties of the high-permeability piezomagnetic thin strip. When the magnetoelectric antenna is working, on the one hand, multiple columns of elastic waves generated in the elastic substrate by the piezoelectric resonator array with a specific spacing on the lower surface are superimposed at each unit to form the antinode of the standing wave, thereby realizing the elastic field coupling effect between multiple units, and significantly enhancing the magnetoelastic energy of the magnetic moment resonance of the driving piezomagnetic thin strip; on the other hand, the variable-amplitude double-wedge-shaped high-permeability piezomagnetic thin strip is used to converge the magnetic field generated by the inverse magnetoelectric effect of the adjacent magnetoelectric units, so as to realize the strong magnetic field coupling effect between multiple units. In order to further realize the magnetic field amplification function within a wide bandwidth, this project plans to use piezoelectric materials with large piezoelectric coefficients but moderate Q values ​​(such as piezoelectric single crystals) to drive the magnetoelectric transmitting antenna array to generate an AC magnetic field to regulate the magnetic permeability and magnetic resistance of the soft magnetic shielding layer outside the permanent magnet. By periodically controlling the opening and closing of the magnetic flux circuit, the static magnetic energy of the permanent magnet is modulated into an AC magnetic field and emitted into the air. At this time, the AC magnetic field generated by the permanent magnet will further intensify the magnetic moment oscillation of the piezoelectric magnetic layer in the magnetoelectric unit, thereby increasing the transmitting magnetic field generated by the magnetoelectric antenna array. This positive feedback process continues until the magnetic moments of the two magnetic sources reach a balanced state, thereby amplifying the transmitting magnetic field without increasing the power consumption of the magnetoelectric antenna, thereby achieving wide-band and high magnetic field transmission efficiency.

Claims

1. A multi-field driven positive feedback very low frequency magnetoelectric antenna array, characterized in that: It comprises a plurality of magnetoelectric units distributed in an array, and a plurality of permanent magnets wrapped by a soft magnetic shielding layer; The magnetoelectric unit includes a strong hysteresis pressure magnetic layer, a special-shaped high-permeability piezomagnetic thin strip, a grid-shaped elastic substrate and a piezoelectric layer from top to bottom; the grid-shaped elastic substrates of each magnetoelectric unit are connected in pairs, and the input end of the piezoelectric layer is externally connected to an AC high-voltage source. Under the excitation of the AC voltage, the piezoelectric layer generates an AC stress that is transmitted to the strong hysteresis pressure magnetic layer of the current magnetoelectric unit to cause magnetic moment oscillation, thereby generating an AC magnetic field; at the same time, the AC stress generated by the piezoelectric layer is transmitted to the adjacent magnetoelectric unit via the grid-shaped elastic substrate, and the emission magnetic field of the magnetoelectric unit is enhanced through the elastic field / magnetic field coupling effect of multiple magnetoelectric units; The AC magnetic field generated by the magnetoelectric antenna array regulates the magnetic permeability of the soft magnetic shielding layer around each permanent magnet so that the permanent magnet generates an AC magnetic field, and the AC magnetic field is fed back to the special-shaped high-permeability piezomagnetic thin strip of the magnetoelectric antenna array to enhance the AC magnetic field generated by the magnetoelectric antenna array.

2. The multi-field driven positive feedback very low frequency magnetoelectric antenna array according to claim 1, characterized in that: A built-in magnetic field is formed between the strong hysteresis piezomagnetic layer 1 and the special-shaped high-permeability piezomagnetic thin strip 2 .

3. The multi-field driven positive feedback very low frequency magnetoelectric antenna array according to claim 1, characterized in that: The special-shaped high-permeability piezomagnetic thin strip 2 includes four triangular magnetic convergence areas 8-1 and a central target area 8-2 surrounded by the four triangular magnetic convergence areas; the triangular magnetic convergence area 8-1 converges the emission magnetic field generated by the surrounding magnetoelectric units to the central target area 8-2.

4. The multi-field driven positive feedback very low frequency magnetoelectric antenna array according to claim 1, characterized in that: The grid-like elastic substrate 3 is arranged in a grid-like manner with a horizontal and vertical staggered arrangement, and the lower surface 9-1 at the horizontal and vertical staggered position fixes the piezoelectric layer 4, and the upper surface 9-2 fixes the heterojunction array of the special-shaped high magnetic permeability piezomagnetic thin strip 2 and the strong hysteresis piezomagnetic layer 1.

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