Self-biased composite source magnetoelectric coil transmitting antenna

Abstract

The invention provides a self-biased composite source magnetoelectric coil transmitting antenna, which belongs to the technical field of wireless communication and comprises a magnetoelectric antenna and a coil wound outside the magnetoelectric antenna. The magnetoelectric antenna comprises a first magnetostriction layer, a piezoelectric layer and a second magnetostriction layer which are sequentially stacked; an upper electrode layer and a lower electrode layer are respectively arranged on the upper surface and the lower surface of the piezoelectric layer; the upper electrode layer, the coil and the lower electrode layer are sequentially connected in series; the series resonant frequency after the upper electrode layer, the coil and the lower electrode layer are sequentially connected in series is equal to the resonant frequency of the magnetoelectric antenna. The capacitive magnetoelectric antenna and the coil are connected in series, the electrified coil not only can provide a bias magnetic field for the magnetoelectric antenna, but also can form series resonance with the magnetoelectric antenna at a target resonant frequency by accurately adjusting the number of turns of the coil, so that the overall impedance of the circuit is reduced, the current of the circuit is increased, and the bias magnetic field of the magnetoelectric antenna is enhanced; and the radiation capability of the antenna is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless communications, and in particular relates to a self-biased composite source magnetoelectric coil transmitting antenna. Background Art

[0002] With the miniaturization of electronic devices and the growing demand for portability, antennas are essential for sending and receiving communication signals, but they face limitations due to their physical size. High-frequency signals have poor penetration and large attenuation, which limits their effectiveness in underwater and underground environments. For low-frequency communications, the skin effect of electromagnetic waves is not significant, and their excellent penetration and anti-interference capabilities give them unmatched advantages over high-frequency electromagnetic waves in complex environments such as underwater and underground. However, traditional low-frequency antennas have large physical sizes, which inevitably bring disadvantages such as high cost, high energy consumption and low transmission efficiency.

[0003] The existing magnetoelectric antenna uses a permanent magnet to provide a bias magnetic field. At the same time, due to the high Q value of the magnetoelectric antenna, it can only radiate in a narrow band, and the radiation capability of a single magnetoelectric antenna is relatively weak. Summary of the invention

[0004] The present invention provides a self-biased composite source magnetoelectric coil transmitting antenna to solve the problems in the prior art that the magnetoelectric antenna is provided with a bias magnetic field by a permanent magnet and can only radiate in a narrow band, and the radiation capability of a single magnetoelectric antenna is relatively weak.

[0005] The present invention provides a self-biased composite source magnetoelectric coil transmitting antenna, comprising a magnetoelectric antenna and a coil wound outside the magnetoelectric antenna;

[0006] The magnetoelectric antenna comprises a first magnetostrictive layer, a piezoelectric layer and a second magnetostrictive layer which are stacked in sequence; an upper electrode layer and a lower electrode layer are respectively arranged on the upper surface and the lower surface of the piezoelectric layer; the upper electrode layer, the coil and the lower electrode layer are sequentially connected in series;

[0007] The series resonant frequency of the upper electrode layer, the coil and the lower electrode layer connected in series in sequence is equal to the resonant frequency of the magnetoelectric antenna.

[0008] Optionally, the magnetization directions of the first magnetostrictive layer and the second magnetostrictive layer are both along the length direction of the magnetoelectric antenna; and the polarization direction of the piezoelectric layer is along the thickness direction of the magnetoelectric antenna.

[0009] Optionally, the series resonant frequency f after the upper electrode layer, the coil and the lower electrode layer are connected in series in sequence is calculated according to the following formula: r :

[0010]

[0011] Among them, π is the ratio of circumference to diameter; Lcoil is the inductance of the coil; C ME is the capacitance value of the equivalent capacitor formed by the upper electrode layer and the lower electrode layer.

[0012] Alternatively, calculate C according to the following formula ME :

[0013]

[0014] Wherein, ε is the dielectric constant of the piezoelectric layer; S is the lower surface area of ​​the upper electrode layer or the lower electrode layer; and d is the thickness of the piezoelectric layer.

[0015] Optionally, it also includes a magnetoelectric antenna shell; the magnetoelectric antenna is located inside the magnetoelectric antenna shell; and the coil is wound outside the magnetoelectric antenna shell.

[0016] Optionally, the first magnetostrictive layer and the second magnetostrictive layer have the same thickness, and both are smaller than the thickness of the piezoelectric layer.

[0017] Optionally, the material of the first magnetostrictive layer and the second magnetostrictive layer are both one of Terfenol-D, Metglas, GaFe alloy or CoFe alloy.

[0018] Optionally, the material of the piezoelectric layer is one of piezoelectric ceramics, aluminum nitride, lithium niobate, zinc oxide or polymer piezoelectric materials.

[0019] Optionally, the material of the upper electrode layer and the lower electrode layer are both one of Au, Ag, Al, Cu, Pt, W, Fe, Co, Ni or Ti.

[0020] Optionally, the material of the magnetoelectric antenna shell is CBY SLA photosensitive resin.

[0021] The present invention provides a self-biased composite source magnetoelectric coil transmitting antenna, which connects a capacitive magnetoelectric antenna and a coil in series. The energized coil can not only provide a bias magnetic field for the magnetoelectric antenna, but also form a series resonance with the magnetoelectric antenna at a target resonant frequency by accurately adjusting the number of turns of the coil, thereby reducing the overall impedance of the circuit, increasing the current of the circuit, and further enhancing the bias magnetic field of the magnetoelectric antenna, thereby improving the radiation capability of the antenna. At the same time, due to the series resonance, the loop impedance is minimized and the current is maximized, which also excites the coil to generate an externally radiated magnetic field. The radiation of the magnetoelectric antenna and the radiation of the coil work together to greatly enhance the radiation intensity of the magnetic field antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic structural diagram of a self-biased composite source magnetoelectric coil transmitting antenna provided in an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the structure of a magnetoelectric antenna provided in an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of the structure of a magnetoelectric antenna housing provided by an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of the connection of a magnetoelectric coil transmitting antenna provided in an embodiment of the present invention;

[0027] Figure 5 An equivalent circuit diagram of the connection between the magnetic coil transmitting antenna provided by an embodiment of the present invention;

[0028] Figure 6 A schematic diagram of a magnetoelectric coil transmitting antenna provided in an embodiment of the present invention;

[0029] Figure 7 A comparison chart of the transmission performance between the magnetoelectric coil antenna and the single magnetoelectric antenna provided in an embodiment of the present invention;

[0030] Figure 8 A capacitance measurement diagram under an alternating magnetic field provided by an embodiment of the present invention;

[0031] Fig. 9 A schematic diagram of a test of the radiation capability of a magnetoelectric coil transmitting antenna provided in an embodiment of the present invention;

[0032] Fig.10 A diagram showing the relationship between the induced voltage and transmission distance of the magnetic bar coil receiver provided in an embodiment of the present invention.

[0033] Among them, 1. magnetoelectric antenna, 11. first magnetostrictive layer, 12. piezoelectric layer, 121. upper electrode layer, 122. lower electrode layer, 13. second magnetostrictive layer; 2. coil; 3. magnetoelectric antenna housing. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In one embodiment, if Figure 1 As shown, this embodiment provides a self-biased composite source magnetoelectric coil transmitting antenna, comprising a magnetoelectric antenna 1 and a coil 2 wound outside the magnetoelectric antenna 1 .

[0036] like Figure 2 As shown, the magnetoelectric antenna 1 includes a first magnetostrictive layer 11, a piezoelectric layer 12, and a second magnetostrictive layer 13 which are stacked in sequence; an upper electrode layer 121 and a lower electrode layer 122 are respectively arranged on the upper surface and the lower surface of the piezoelectric layer 12; the upper electrode layer 121, the coil 2, and the lower electrode layer 122 are connected in series in sequence. The length directions of the first magnetostrictive layer 11, the piezoelectric layer 12, and the second magnetostrictive layer 13 are all parallel to the axial direction of the coil 2; the magnetization directions of the first magnetostrictive layer 11 and the second magnetostrictive layer 13 are all along the length direction of the magnetoelectric antenna 1; and the polarization direction of the piezoelectric layer 12 is along the thickness (height) direction of the magnetoelectric antenna 1.

[0037] The magnetoelectric antenna 1 is optimized according to the desired frequency, and then the magnetoelectric antenna 1 and the winding coil 2 are manufactured, and then the magnetoelectric antenna 1 and the coil 2 are connected in series, and the number of turns of the coil 2 is precisely adjusted so that the series resonant frequency f after the upper electrode layer 121, the coil 2 and the lower electrode layer 122 are connected in series in sequence is r Resonant frequency f with magnetoelectric antenna 1 ME equal.

[0038] According to the series resonant circuit theory, near the resonant frequency, the impedance of the circuit is very low, resulting in high energy transfer efficiency. In contrast, at frequencies outside the resonant frequency, the circuit exhibits high impedance, resulting in significant signal energy attenuation.

[0039] Exemplarily, f is calculated according to the following formula r :

[0040]

[0041] Among them, π is the ratio of circumference to diameter; L coil is the inductance of coil 2; C ME is the capacitance value of the equivalent capacitor formed by the upper electrode layer 121 and the lower electrode layer 122; f r By ME Sure.

[0042] The upper electrode layer 121 and the lower electrode layer 122 can be conceptualized as a capacitor, with the upper electrode layer 121 and the lower electrode layer 122 serving as two plates, respectively. When a voltage is applied to the piezoelectric layer 12, positive and negative charges accumulate at the corresponding poles of the plates, thereby forming a simple capacitor, and C is calculated according to the following formula: ME :

[0043]

[0044] Wherein, ε is the dielectric constant of the piezoelectric layer 12; S is the lower surface area of ​​the upper electrode layer 121 or the lower electrode layer 122; and d is the thickness of the piezoelectric layer 12. Exemplarily, the material of the upper electrode layer 121 and the lower electrode layer 122 includes but is not limited to one of Au, Ag, Al, Cu, Pt, W, Fe, Co, Ni, or Ti.

[0045] For the magnetoelectric antenna 1, the material and physical size of the magnetoelectric antenna 1 determine the resonant frequency of its operation. In this embodiment, the thickness of the first magnetostrictive layer 11 and the second magnetostrictive layer 13 are the same, and both are less than the thickness of the piezoelectric layer 12. The materials of the first magnetostrictive layer 11 and the second magnetostrictive layer 13 include but are not limited to one of Terfenol-D, Metglas, GaFe alloy or CoFe alloy. The material of the piezoelectric layer 12 includes but is not limited to one of piezoelectric ceramics, aluminum nitride, lithium niobate, zinc oxide or polymer piezoelectric materials, and the piezoelectric ceramics include barium titanate, lead zirconate titanate and lead magnesium niobate piezoelectric ceramics.

[0046] In this embodiment, Figure 2 As shown, the piezoelectric layer 12 is made of PZT-5H piezoelectric ceramics with a size of 60mm×30mm×0.5mm; the material of the first magnetostrictive layer 11 and the second magnetostrictive layer 13 is Metglas2605M, and the size is 60mm×30mm×0.13mm. After simulation with COMSOL Multiphysics 6.0 finite element simulation software, when the bias magnetic field is 20 Oersted, the simulated magnetoelectric antenna 1 has an operating frequency of 27.45kHz. The measured resonant frequency of the magnetoelectric antenna is 27.71kHz, which matches the simulated resonant frequency well.

[0047] In order to avoid winding the coil 2 directly onto the magnetoelectric antenna 1, which may affect the stress transfer in the piezoelectric layer 12 and thus affect the radiation performance of the magnetoelectric antenna 1, the coil 2 needs to be wound around the magnetoelectric antenna housing 3. Figure 3 As shown, the inner cavity size of the magnetoelectric antenna housing 3 is 64mm×34mm×4mm. The material of the magnetoelectric antenna housing 3 is CBY SLA photosensitive resin, which has good temperature resistance and toughness, and can prevent the magnetoelectric antenna housing 3 from being deformed due to overheating of the coil 2.

[0048] like Figure 4 and Figure 5 As shown, under the condition of a constant driving voltage, two wires are welded on the piezoelectric layer 12 at the edges of the upper electrode layer 121 and the lower electrode layer 122 as the positive and negative electrodes of the magnetoelectric antenna 1, and are connected in series with the coil 2 composed of 120 turns of multi-strand wires with a specification of 0.1mm*25 strands, wherein the magnetoelectric antenna 1 is used as a magnetic core. This configuration enhances the inductance of the coil 2 and strengthens the magnetic field generated by the coil 2, thereby improving the radiation capability of the magnetoelectric antenna 1, Z t is the overall impedance of the coil 2 and the magnetoelectric antenna 1 in the series circuit.

[0049] like Figure 6 As shown, since the magnetic field generated by coil 2 is significantly lower than the optimal bias magnetic field, a larger magnetic field will improve the radiation capability of magnetoelectric antenna 1. On the one hand, Metglas2605M is a soft magnetic material with a high magnetic permeability, which is suitable as the magnetic core of coil 2. When placed in coil 2, the magnetostrictive layers (first magnetostrictive layer 11 and second magnetostrictive layer 13) inside coil 2 will converge magnetic lines of force, thereby increasing the inductance of coil 2 and enhancing the bias magnetic field. On the other hand, the series resonance with magnetoelectric antenna 1 can effectively reduce the overall impedance of the circuit, increase the circuit current, and further enhance the bias magnetic field, thereby increasing the inverse magnetoelectric coupling coefficient of magnetoelectric antenna 1, and finally the radiation capability of magnetoelectric antenna 1 is effectively enhanced.

[0050] like Figure 7 As shown, in the measurement, the self-biased composite source magnetoelectric coil transmitting antenna used in this embodiment is directly connected to the signal source. At the same time, the induced voltage is measured using a magnetic rod antenna. The test conditions are as follows: the signal source output amplitude is set to 20V pp Sine wave signal, the right end of the single magnetoelectric antenna and magnetoelectric coil antenna transmitter is located 10 cm away from the left end of the magnetic rod antenna. Use an oscilloscope to record the induced voltage at the magnetic rod antenna. The results show that the magnetic induction intensity of the magnetoelectric coil antenna is 3.17 times that of the magnetoelectric antenna and 5.43 times that of the air-core coil. It is worth noting that the induced voltage generated by the magnetoelectric coil antenna is significantly greater than the sum of the induced voltages generated by the magnetoelectric antenna and the air-core coil. At the same time, the magnetoelectric antenna characterized by a high Q factor sacrifices bandwidth for this characteristic. Figure 7 As shown in the figure, the 3dB bandwidth of the magnetoelectric antenna is 1.48kHz. In contrast, the 3dB bandwidths at the two resonant frequencies (25.70kHz and 32.12kHz) of the magnetoelectric coil antenna are 6.2kHz and 16.75kHz, respectively. These values ​​are 4.19 times and 11.12 times that of the magnetoelectric antenna, respectively. Figure 8 As shown, this phenomenon occurs because the alternating magnetic field changes the electric field and charge distribution of the antenna, causing a sudden change in capacitance. rAccording to the calculation formula, the resonant frequency shifts due to these capacitance changes.

[0051] like Fig. 9 As shown, a power amplifier is used at the transmitting end to amplify the source voltage, and a capacitor is used to resonate in parallel with the receiving coil to improve the reception effect. The resonant frequency of the receiving coil is tuned to 32.12kHz.

[0052] like Fig.10 As shown in the figure, the test shows that the input power of the magnetic coil transmitting antenna is about 370.1mW. The relationship between the measured induced voltage value of the magnetic rod antenna and the communication distance is shown in Fig.10 As shown. It can be seen that even at a communication distance of up to 2m, the induced voltage at the receiving end can be as high as 7.44mV. The test results show that the antenna is suitable for low-frequency short-distance communication. It can be seen that the magnetoelectric coil transmitting antenna exhibits good radiation capability. In addition, the induced voltage decays approximately in third order with distance.

[0053] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A self-biased composite source magnetoelectric coil transmitting antenna, characterized in that: It comprises a magnetoelectric antenna (1) and a coil (2) wound around the outside of the magnetoelectric antenna (1); The magnetoelectric antenna (1) comprises a first magnetostrictive layer (11), a piezoelectric layer (12) and a second magnetostrictive layer (13) which are stacked in sequence; an upper electrode layer (121) and a lower electrode layer (122) are respectively arranged on the upper surface and the lower surface of the piezoelectric layer (12); the upper electrode layer (121), the coil (2) and the lower electrode layer (122) are sequentially connected in series; The series resonance frequency of the upper electrode layer (121), the coil (2) and the lower electrode layer (122) connected in series is equal to the resonance frequency of the magnetoelectric antenna (1).

2. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 1, characterized in that: The magnetization directions of the first magnetostrictive layer (11) and the second magnetostrictive layer (13) are both along the length direction of the magnetoelectric antenna (1); and the polarization direction of the piezoelectric layer (12) is along the thickness direction of the magnetoelectric antenna (1).

3. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 1, characterized in that: The series resonant frequency f after the upper electrode layer (121), the coil (2) and the lower electrode layer (122) are connected in series in sequence is calculated according to the following formula: r : Among them, π is the ratio of circumference to diameter; L coil is the inductance of the coil (2); C ME is the capacitance value of the equivalent capacitance formed by the upper electrode layer (121) and the lower electrode layer (122).

4. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 3, characterized in that: Calculate C according to the following formula ME : Wherein, ε is the dielectric constant of the piezoelectric layer (12); S is the lower surface area of ​​the upper electrode layer (121) or the lower electrode layer (122); and d is the thickness of the piezoelectric layer (12).

5. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 1, characterized in that: It also comprises a magnetoelectric antenna shell (3); the magnetoelectric antenna (1) is located inside the magnetoelectric antenna shell (3); and the coil (2) is wound outside the magnetoelectric antenna shell (3).

6. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 1, characterized in that: The thicknesses of the first magnetostrictive layer (11) and the second magnetostrictive layer (13) are the same, and both are smaller than the thickness of the piezoelectric layer (12).

7. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 1, characterized in that: The materials of the first magnetostrictive layer (11) and the second magnetostrictive layer (13) are both selected from the group consisting of Terfenol-D, Metglas, GaFe alloy and CoFe alloy.

8. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 1, characterized in that: The material of the piezoelectric layer (12) is one of piezoelectric ceramics, aluminum nitride, lithium niobate, zinc oxide or polymer piezoelectric materials.

9. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 1, characterized in that: The material of the upper electrode layer (121) and the lower electrode layer (122) is one of Au, Ag, Al, Cu, Pt, W, Fe, Co, Ni or Ti.

10. The self-biased composite source magnetoelectric coil transmitting antenna according to claim 5, characterized in that: The material of the magnetoelectric antenna housing (3) is CBY SLA photosensitive resin.

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