Artificial electret and electret antenna

Abstract

The present invention discloses an artificial electret and an electret antenna. The artificial electret includes: a first electrode for connecting to the positive electrode of a power supply; a second electrode for connecting to the negative electrode of a power supply; a metal layer, one of two adjacent metal layers is connected to the first electrode, and the other of the two adjacent metal layers is connected to the second electrode; and a dielectric layer, a dielectric layer is arranged between two adjacent metal layers. The electret of the present invention includes a positive electrode plate, a negative electrode plate, multiple metal layers and multiple high-dielectric dielectric layers. The high-dielectric dielectric layer is located between the metal layers, providing the metal layers with anti-breakdown capability, thereby increasing the amount of charge stored in the metal layers. When the electret rotates, the ability to generate a time-varying electric field in space can be achieved. A large amount of charge is provided to the multiple metal layers through the positive electrode plate and the negative electrode plate. The surface charge density is more than 20 times that of the passive electret under the same size, and the multi-layer structure can increase the electric dipole moment, greatly improving the communication distance.

Description

Technical Field

[0001] The invention relates to the technical field of ultra / very low frequency transmitting antennas, and in particular to a high-efficiency and highly anti-interference electret ultra / very low frequency antenna. Background Art

[0002] Ultra / very low frequency communication technology is a technology that uses the ultra / very low frequency spectrum in the radio spectrum for wireless communication. Ultra / very low frequency electromagnetic waves have the following advantages due to their low loss, strong anti-interference ability, and stable and reliable propagation: 1. The attenuation of ultra-low frequency signals propagating in the earth's crust is much lower than that of other commonly used low-frequency signals, so they can have a higher penetration depth; 2. Ultra-low frequency signals are insensitive to unreliable propagation conditions, and their propagation is stable and reliable. They are one of the very few communication methods that are not damaged by electromagnetic waves; 3. They have strong anti-interference ability. If you try to interfere with ultra-low frequency communication, you must have a stronger power output than the ultra-low frequency communication signal.

[0003] Although ultra / very low frequency communication has so many advantages, the biggest problem of ultra-low frequency communication is how to effectively generate ultra-low frequency electromagnetic waves.

[0004] Traditional ultra-low frequency antennas are electric field antennas or magnetic field antennas. Due to their small size, the radiation resistance is low, and a large oscillating current is required to generate significant radiation power. The huge size of the antenna is easily destroyed during war, which is not conducive to military use.

[0005] The introduction of "mechanical antenna" solves the problems of large size, poor flexibility and poor concealment of ultra-low frequency antennas. However, the current rotating permanent magnet / electret mechanical antennas are directly driven and are seriously affected by the electromagnetic interference generated by the motor itself. At close distances, it is impossible to distinguish whether the electromagnetic signal is generated by the motor or the radiation source. For radiation sources, the magnetic energy density of permanent magnets is difficult to increase, and the radiation intensity can only be increased by increasing the volume, which brings huge challenges to rotating machinery; natural electrets have poor charge storage capabilities and generate a small electric dipole moment when rotated, making it difficult to achieve long-distance transmission requirements. Cui Yong's team at the Beijing University of Aeronautics and Astronautics conducted research on passive electrets and only completed 0.1m@1nT communications. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an electret and an electret antenna with long transmission distance, no interference from the driving structure itself and high stability.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] The present invention first provides an electret, which is characterized by comprising:

[0009] A first electrode, used to be connected to a positive electrode of a power source;

[0010] A second electrode, used to be connected to a negative electrode of a power source;

[0011] A metal layer, wherein one of two adjacent metal layers is connected to the first electrode, and the other of the two adjacent metal layers is connected to the second electrode;

[0012] as well as

[0013] A dielectric layer is provided between two adjacent metal layers.

[0014] The electret of the present invention comprises a positive electrode plate, a negative electrode plate, a metal layer and a high dielectric layer. The high dielectric layer is located between the metal layers, providing the metal layer with anti-breakdown capability, thereby increasing the amount of charge stored in the metal layer. When the electret rotates, the ability to generate a time-varying electric field in space can be achieved. A large amount of charge is provided to the metal layer by the positive electrode plate and the negative electrode plate. The surface charge density is more than 20 times that of a passive electret at the same size, and the multilayer structure can increase the electric dipole moment. Assuming that there are (n+1) / 2 layers of metal, the communication distance can be increased by n20 times.

[0015] The present invention also provides a high-efficiency and highly anti-interference electret antenna, including a driving structure and an antenna radiation source, wherein the driving mechanism is used to drive the antenna radiation source to rotate, and the antenna radiation source adopts the electret. The electret antenna of the present invention adopts a speed increaser, so that the electret rotation frequency is inconsistent with the operating frequency of the driving motor, so that the electret antenna is not interfered by the electromagnetic signal of the motor, and the cumbersome process of applying a shielding cover to the motor is avoided. The electret of the present invention adopts a multi-layer stacking structure of parallel plate patches, so that the electret has a larger electric dipole moment under the same volume, thereby generating a stronger radiation field. The electret antenna involved in the present invention reduces the complexity of the antenna structure and improves the working stability of the electret antenna through a speed increaser, a multi-layer stacking structure and a dynamic balancing block. The present invention can improve the radiation intensity of the electret antenna by increasing the rotation speed, increasing the strength of the applied voltage and increasing the number of stacking layers.

[0016] The high-efficiency and strong-interference electret antenna of the present invention rotates the electret to realize the rotation of positive and negative charges on the metal layer, that is, the rotation of the electric dipole moment, thereby generating a time-varying electric field. This mechanical antenna avoids the practice of traditional electric antennas loading excitation voltage at the feeder port to generate oscillating electromagnetics inside the conductor. This solution solves the problem of low natural electret charge density and inability to improve permanent magnetic energy in mechanical antennas of the same type, and also solves the problem of electromagnetic interference and high-speed and stable rotation of the mechanical antenna drive structure.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The signal transmitting module in the device of the present invention can realize a time-varying electric field different from the operating frequency of the motor, thereby shielding the electromagnetic interference generated by the motor.

[0019] 2. The device of the present invention uses electret as the emission source, which can be used permanently without considering the impedance matching problem. Amplitude modulation can be achieved by changing the size of the external power supply, and frequency modulation can be achieved by changing the rotation speed; amplitude modulation can be achieved by changing the external applied voltage waveform; large surface charge density can be achieved by applying a large voltage. According to communication requirements, without changing the source, only the external excitation voltage is changed to meet the requirements, avoiding resource waste.

[0020] 3. The electret in the device of the present invention adopts a material with a high dielectric constant (such as barium titanate) and a multilayer structure to achieve the ability of high charge density and high electric dipole moment, and the radiation ability of the electret in the present invention can be controlled.

[0021] 4. The device of the present invention adopts ultra / very low frequency communication, with small propagation loss, long transmission distance and strong anti-interference ability.

[0022] 5. The design of the dynamic balancing block in the device of the present invention can realize high-speed and stable operation of the radiation source. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 The overall structure of the electret mechanical antenna of the present invention;

[0025] Figure 2 It is a schematic diagram of the overall structure of the electret mechanical antenna of the present invention;

[0026] Figure 3 It is a schematic diagram of the electret structure of the present invention;

[0027] Figure 4 It is a schematic diagram of the bearing seat structure of the present invention;

[0028] Figure 5 It is a schematic diagram of the movable clamp structure of the present invention;

[0029] Figure 6 These are the simulation results of multi-layer and single-layer charge density of the electret of the present invention under the same volume; (a) is the simulation model of a single-layer electret, and (b) is the simulation model of a multi-layer electret.

[0030] Reference numerals:

[0031] 11-protective housing; 12-driving motor; 13-coupling; 14-coupling support frame; 15-speed increaser; 16 power carrier; 17-electret; 18-dynamic balancing block; 19-clamp; 21-metal layer; 22-high dielectric layer; 23-left side electrode; 24-right side electrode; 31-bearing; 32-bearing base; 41-air domain; 42-infinite element domain; 191-rotating handle; 192-driving block; 193-support frame; 194-fixing hole. DETAILED DESCRIPTION

[0032] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0033] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0034] In the description of this application, unless otherwise clearly specified and limited, the terms "metal layer", "coupling", "drive motor", "medium layer", "bracket", "clamp" and the like should be understood in a broad sense. For example, it can be a coupling connected to a motor, or it can be a coupling connected to other rotating mechanisms. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] like Figure 1 As shown in FIG. 1 , a high-efficiency and strong anti-interference electret antenna structure block diagram provided by the present invention includes a driving module and a radiation source module. The driving module includes a power supply, a driving motor, a frequency converter, a coupling, a speed increaser and a clamp; the radiation source is a mobile power supply, a power carrier, a dynamic balance block and a Figure 3 The electret shown.

[0036] like Figure 2 As shown, the present invention provides a high-efficiency and strong anti-interference electret antenna, including a protective housing 11, a drive motor 12, a coupling 13, a coupling support frame 14, a speed increaser 15, a power carrier 16, an electret 17, a dynamic balance block 18 and a fixture 19. The drive motor 12 is fixed on the protective housing 11, and the drive motor 12 is connected to the speed increaser 15 through the coupling 13.

[0037] The clamp 19 includes two clamps, namely a first clamp and a second clamp, wherein the first clamp is located at the bottom and the second clamp is located at the top. The speed increaser 15 is connected to the first clamp via a coupling 13 .

[0038] The first clamp has the same structure as the second clamp, and both include a rotating handle 191, a driving block 192, and a support frame 193. There are two driving blocks 192, which can slide along the support frame 193 guided by the support frame 193. The driving block 192 is threadedly connected to the rotating handle 191, and the distance between the two driving blocks 192 can be adjusted by rotating the rotating handle 191.

[0039] The clamp 19 clamps the electret 17 through the clamping block 192, and the clamp 19 is fixed to the power carrier 16 through the fixing threaded hole 194. The power carrier 16 is fixed to the coupling 13, the bearing seat is fixed to the protective shell 11, and the upper coupling 13 is connected to the bearing seat.

[0040] like Figure 3 As shown, it is a schematic diagram of an electret structure provided by the present invention, including a metal layer 21, a high dielectric layer 22, a left side electrode 23 and a right side electrode 24. A high dielectric layer 22 is placed between adjacent metal layers 21, and the first metal layer is named 1 from top to bottom, and the numbers increase gradually. The odd-numbered layers in the metal layer are connected to the left side electrode 23, and the even-numbered layers are connected to the right side electrode 24.

[0041] It should be noted that the number of high-dielectric layers 22 is odd, the metal layers 21 with odd numbers do not contact the right side electrode 24 , and the metal layers 21 with even numbers do not contact the left side electrode 23 .

[0042] It should be noted that the rotation axis of the rotating electret is Figure 3 The axis in the left picture passes through the center of mass and is perpendicular to the paper.

[0043] The physical mechanism of electromagnetic field radiation is specifically expressed as follows: the charge q stored in the outermost metal layer of the electret moves at an angular velocity ω, which can be expressed as the equivalent electric dipole moment rotating around the center point.

[0044] The charge storage capacity of the outermost metal layer 21 of an electret with n high-k dielectric layers 22 (the thickness ratio of the dielectric layer 22 to the metal layer 21 is 5:2) is:

[0045]

[0046] In formula (1), ε r is the dielectric constant of the dielectric layer; S is the area facing the metal layer; U is the external power supply voltage; k0 is the electrostatic force constant; d is the thickness of the dielectric single layer.

[0047] According to Maxwell's electromagnetic field theory, the rotating electric charge radiates electromagnetic field to the outside, and the theoretical formula of field strength is as follows:

[0048]

[0049]

[0050] Where E erot B is the time-varying electric field generated by the rotating artificial electret; erot is the time-varying magnetic field generated by the rotating artificial electret; k = ω / c is the wave number; c is the speed of light in free space; θ is the polar angle of the field point; Φ is the azimuth angle of the field point; q is the charge; l is the distance between the positive and negative charges, that is, the direction from the negative charge to the positive charge; R is the distance between the field point and the source point; a R is the unit vector of the radiation direction; a θ is the unit vector on the polar angle; a φ is a unit vector in azimuth.

[0051] The rotating electret mechanical antenna provided in the embodiment of the present invention uses a rotational motion method to make the electret with a high electric dipole moment rotate, directly generate a time-varying electric field, and thus radiate an electromagnetic field to the outside. This mechanical antenna uses a speed increasing mechanism to avoid the influence of electromagnetic interference of the drive motor, and also avoids the practice of traditional antennas applying voltage to the feeder segment to generate an oscillating electric field inside the conductor. Therefore, the mechanical antenna does not have the problems of high reactance and low radiation impedance. Combined with the characteristics of low reactance and low damping of the mechanical antenna, the mechanical antenna has the characteristics of light weight, small size, low power consumption and high efficiency.

[0052] On the basis of the above embodiment, the sizes of any high-dielectric layer 22 are equal, and the sizes of any metal layer 21 are equal.

[0053] It should be noted that two adjacent metal layers 21 are completely insulated.

[0054] The speed increaser 15 provided in the embodiment of the present invention adopts a 90-degree right-angle structure, which makes the overall structure smaller in size and more stable in fixation.

[0055] The dynamic balancing weight 18 provided in the embodiment of the present invention is installed on the power carrier 16 to prepare for the installation of the dynamic balancing weight for subsequent dynamic balancing detection during high-speed rotation.

[0056] The support frame 14 provided in the embodiment of the present invention is used to support the suspended speed increaser 15, so that the mechanical antenna can operate more smoothly.

[0057] The mobile power supply provided in the embodiment of the present invention is fixed on the power carrier 16 to continuously provide electric energy to the electret 17 .

[0058] It should be noted that a mobile power source is a continuously rechargeable power source.

[0059] The high-efficiency and strong anti-interference electret antenna provided by the embodiment of the present invention adopts a multi-layer stacking structure of parallel plate patches, so that the electret antenna has a larger electric dipole moment within a certain volume, thereby improving the radiation field strength.

[0060] like Figure 4 , which is a schematic diagram of the bearing seat structure provided by the present invention, includes a bearing 31 and a bearing base 32, wherein the bearing 31 is installed in the bearing base 32. The bearing base 32 is fixed to the protective housing 11 by fastening bolts.

[0061] like Figure 5 As shown, it is a schematic diagram of the structure of the clamp 19 provided by the embodiment of the present invention, including a rotating handle 191, a driving block 192, a support frame 193 and a fixing hole 194. The threads on both sides of the center of the rotating handle 191 are rotated in opposite directions. The rotating handle 191 drives the two driving blocks 192 to move synchronously, so that the clamp has good centering. The support frame 193 is used to support and fix the driving block 192. The fixing hole 194 is used to fix the clamp 19 and the power carrier 16. Therefore, the distance between the driving blocks 192 can be adjusted by rotating the handle 191 to clamp artificial electrets of different widths.

[0062] like Figure 6 As shown, it is a simulation model provided by the present invention. The model is a simulation model of the charge contained in the outermost metal of a single-layer electret and a multi-layer electret when the volume is equal, where (a) is a simulation model of a single-layer electret, and (b) is a simulation model of a multi-layer electret. In order to simulate closer to the actual situation, an infinite element domain 42 is added to simulate infinite space. The surface charge of a single-layer electret is obtained by Comsol simulation software to be 1.2×10 -7 C, the charge of the outermost plate of the multilayer electret is 4.75×10 -5 C, 396 times that of a single-layer electret.

[0063] The amount of charge stored in a single electret metal layer is:

[0064]

[0065] Therefore, when the volumes are equal, the relationship between the charge contained in the outermost metal of a single-layer electret and a multi-layer electret is:

[0066]

[0067] Figure 6 In the simulation, the number of high-dielectric layers is 143, and the charge of the outermost plate of the multilayer electret is 398 times that of the single-layer electret, which is consistent with the simulation results. Therefore, under the same volume, the multilayer electret in the present invention has a large electric dipole moment.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not cause the corresponding technical solutions to essentially deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An artificial electret, characterized in that: include: A first electrode, used to be connected to a positive electrode of a power source; A second electrode, used to be connected to a negative electrode of a power source; A metal layer, wherein one of two adjacent metal layers is connected to the first electrode, and the other of the two adjacent metal layers is connected to the second electrode; as well as A dielectric layer is provided between two adjacent metal layers; The number of layers of the dielectric layer is n, and the value of n is determined according to the radiation intensity and plate area required for communication; The method for determining the number of dielectric layers n according to the radiation intensity and plate area required for communication is: Where q is the charge; ε r is the dielectric constant of the dielectric layer; S is the plate area; U is the external power supply voltage; k0 is the electrostatic force constant; d is the single layer thickness of the dielectric layer; The charge q is calculated based on the radiation intensity: Among them, E erot B is the time-varying electric field generated by the rotating artificial electret; erot is the time-varying magnetic field generated by the rotating artificial electret; k = ω / c is the wave number; c is the speed of light in free space; is the polar angle of the field point; Φ is the azimuth of the field point; l is the distance between the positive and negative charges, that is, the direction from the negative charge to the positive charge; R is the distance between the field point and the source point; a R is the unit vector of the radiation direction; a θ is the unit vector on the polar angle; a φ is a unit vector in azimuth.

2. An artificial electret according to claim 1, characterized in that: The dielectric constant of the dielectric layer is 4000-8000.

3. An electret antenna, comprising a driving structure and an antenna radiation source, wherein the driving mechanism is used to drive the antenna radiation source to rotate, and is characterized in that: The antenna radiation source adopts the artificial electret described in claim 1 or 2.

4. The electret antenna according to claim 3, characterized in that: The antenna driving structure is a speed-increasing structure, including a driving motor, a coupling and a speed-increasing gear; the coupling connects the driving motor and the speed-increasing gear; the electret is connected to the speed-increasing gear.

5. The electret antenna according to claim 4, characterized in that: The speed increaser is a right-angle structure in which the input shaft and the output shaft are perpendicular to each other, wherein the input shaft is in the horizontal direction and the output shaft is in the vertical direction; the speed increaser is connected to the electret in the vertical direction; and the speed increaser is connected to the drive motor in the horizontal direction.

6. The electret antenna according to claim 5, characterized in that: The electret is arranged on a fixture, and the fixture is connected to the speed increaser.

7. An electret antenna according to any one of claims 3 to 6, characterized in that: The antenna radiation source also includes a radiation power supply, a power supply carrier and a dynamic balancing block; the electret is connected to the radiation power supply; the radiation power supply and the dynamic balancing block are arranged on the power supply carrier.

8. The electret antenna according to claim 7, characterized in that: The clamp comprises a first clamp and a second clamp; the lower end of the power carrier is connected to the first clamp; the upper end of the power carrier is connected to the second clamp; the upper and lower ends of the electret are respectively fixed on the first clamp and the second clamp.

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