Parallel multi-coil magnetic antenna and transparent magnetic communication system

Abstract

The invention relates to the technical field of magnetic communication, in particular to a parallel multi-coil magnetic antenna and a transmitting magnetic communication system.The structure of the magnetic antenna is improved, a plurality of coils are wound on a magnetic core in parallel or in an overlapped mode, and the two ends of each coil are provided with connecting ends used for being connected with a signal driving circuit; the length and winding turns of each coil are the same, so that the size of the antenna is greatly reduced on the premise of not reducing the performance of the antenna; the magnetic antenna structure is applied to a magnetic communication transmitting antenna and a geomagnetic transmission communication system so as to realize geomagnetic transmission communication and positioning. Through the structural design of the parallel multi-coil closely-wound magnetic core, the effects of small inductance, multiple turns and large current of the transmitting coil in the earth-penetrating communication can be realized, and the application deployment on miniaturized portable earth-penetrating communication equipment is met.

Description

Technical Field

[0001] The present invention relates to the field of magnetic communication technology, and in particular to a parallel multi-coil magnetic antenna and a trans-earth magnetic communication system. Background Art

[0002] When personnel or equipment are active in underground facilities (bunkers and deeply buried facilities), tunnels (basic and complex), cities and natural caves (civil engineering, sewers, basements and caves), traditional radio waves will be absorbed and shielded by the strata or reinforced concrete buildings, making it difficult for underground personnel or equipment to establish communication with ground personnel; GPS or Beidou signals fail, and their relative position coordinates cannot be determined. Magnetic communication uses the time-varying magnetic field signals generated by coils in space for communication. The magnetic field can penetrate non-ferromagnetic media such as soil, sand, and seawater, and is widely used for underground communication. The antenna is the most advanced component of underground communication. The transmitting antenna converts the current carrying information into a space induced magnetic field, and uses the receiving antenna to induce the space electromagnetic field into a current signal. Most of the existing transmitting antennas for underground communication use large-diameter hollow transmitting magnetic antennas, which have problems such as large size and complex structure, and are limited in application in miniaturized portable communication equipment. Summary of the invention

[0003] To this end, the present invention provides a parallel multi-coil magnetic antenna and a through-the-earth magnetic communication system to solve the limitations in the deployment of transmitting antennas of miniaturized and convenient through-the-earth communication equipment. By connecting multiple coils in parallel and tightly wound around the magnetic core, the antenna size can be greatly reduced without reducing the antenna performance.

[0004] According to the design scheme provided by the present invention, on the one hand, a parallel multi-coil magnetic antenna is provided, which is composed of a magnetic core and a coil wound on the magnetic core, and the coil includes N coils wound in parallel, and both ends of each coil are provided with connection terminals for connecting to a signal driving circuit, and each coil has the same length and number of winding turns, wherein N is greater than 1.

[0005] As the parallel multi-coil magnetic antenna of the present invention, further, the N coils are independently wound in parallel on the magnetic core.

[0006] As the parallel multi-coil magnetic antenna of the present invention, further, the magnetic core is provided with a plurality of winding areas for independently winding the coils in parallel, the plurality of winding areas are arranged at equal intervals, and the number of the winding areas is consistent with the number of coils, so that each coil is independently wound in the corresponding winding area of ​​the magnetic core.

[0007] As the parallel multi-coil magnetic antenna of the present invention, further, the N coils are wound in parallel on the magnetic core in an overlapping manner.

[0008] As the parallel multi-coil magnetic antenna of the present invention, further, a winding area for winding the coils in parallel in an alternating manner is provided on the magnetic core, and N coils are wound in parallel from one end of the winding area to the other end of the winding area.

[0009] As the parallel multi-coil magnetic antenna of the present invention, further, the magnetic core adopts a MnZn ferrite core.

[0010] As the parallel multi-coil magnetic antenna of the present invention, further, the diameter of the magnetic core is set according to the antenna application scenario.

[0011] On the other hand, the present invention also provides a magnetic communication transmitting antenna, which adopts the above-mentioned parallel multi-coil magnetic antenna structure.

[0012] On the other hand, the present invention also provides a through-the-earth magnetic communication system for communication between ground through-the-earth communication equipment and underground through-the-earth communication equipment, wherein the ground through-the-earth communication equipment and the underground through-the-earth communication equipment communicate based on the through-the-earth magnetic communication system, and the through-the-earth magnetic communication system comprises: a signal detection device for detecting magnetic induction communication signals and a signal transceiver module for processing the detected magnetic induction communication signals and sending / receiving the processed signals, wherein the signal detection device comprises a signal transmitting antenna and a signal receiving antenna, and the signal transmitting antenna adopts the above-mentioned magnetic communication transmitting antenna.

[0013] As the through-the-earth magnetic communication system of the present invention, further, the through-the-earth magnetic communication system also includes: a magnetic positioning module, which is used to predict and output the position of the underground through-the-earth communication equipment through position solution based on the magnetic induction communication signal and the prior signal, and the prior signal is a pilot sequence agreed upon by the underground through-the-earth communication equipment and the ground through-the-earth communication equipment.

[0014] Beneficial effects of the present invention:

[0015] The present invention increases the number of coil turns on the basis of increasing the total current of the coil in the antenna by winding the antenna in independent parallel or overlapping parallel manner. The parallel coils use the same number of turns and length, which can ensure the consistency of the electrical parameters of the coils, and then achieve the phase consistency of the current signals of the coils, so that the transmitting antenna can obtain the best magnetic field synthesis effect; the parallel and staggered winding method of multiple coils is used to ensure the best effective magnetic permeability of the magnetic core of the transmitting antenna while ensuring the advantages of parallel coils, and achieve the effects of small inductance, multiple turns and large current of the transmitting coil, which meets the application deployment on miniaturized portable through-the-ground communication equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the transmitting antenna structure in the embodiment;

[0017] Figure 2 This is a schematic diagram of the independent parallel winding structure in the embodiment;

[0018] Figure 3 This is a schematic diagram of the staggered winding structure in the embodiment;

[0019] Figure 4 FIG. 1 is a schematic diagram of the structure of the geomagnetic communication system in the embodiment. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and technical solutions.

[0021] With the continuous development and innovation of magnetic induction technology, it has been widely used in wireless magnetic induction communication, industry, medical treatment, transportation and other fields. Wireless magnetic induction communication is based on Faraday's law of electromagnetic induction. It realizes data transmission by coupling quasi-static magnetic field between transceiver coils. It can overcome the problems of unstable channels and large antenna size in traditional electromagnetic wave wireless communication in extreme environments such as underground or underwater. Figure 1 The transmitting magnetic antenna structure shown is composed of a magnetic core and a coil wound on it. f is the core diameter, l f is the length of the magnetic core. The internal magnetic moment of the antenna represents the strongest magnetic field that the antenna can sense. Its calculation formula is M=NIA, where N is the number of coil turns, I is the current passing through the coil, and A is the cross-sectional area of ​​the coil. It can be seen that the methods to increase the magnetic moment include increasing the number of turns, increasing the current, or increasing the cross-sectional area of ​​the coil. Among them, the inductance calculation formula is:

[0022]

[0023] It can be seen that the inductance is proportional to the square of the number of coil turns N, but when the total driving power is constant, the current I flowing through the antenna is inversely proportional to the inductance L, that is, inversely proportional to the square of the number of turns N and the cross-sectional area A. As mentioned above, the three parameters N, I, and A are interrelated, and it is difficult to increase the antenna magnetic moment directly by optimizing one parameter. In order to break through the bottleneck problems of large volume and complex structure of existing large-diameter hollow transmitting magnetic antennas, an embodiment of the present invention provides a parallel multi-coil magnetic antenna, which is composed of a magnetic core and a coil wound on the magnetic core, and the coil includes N coils wound in parallel, and both ends of each coil are provided with connection terminals for connecting to a signal driving circuit, and each coil has the same length and number of winding turns, wherein N is greater than 1. Through the structure of multiple parallel coils in the antenna, the number of coil turns is increased on the basis of increasing the total current.

[0024] The N coils are independently wound in parallel on the magnetic core. Specifically, a plurality of winding areas for independently winding the coils in parallel are provided on the magnetic core, the plurality of winding areas are arranged at equal intervals, and the number of the winding areas is consistent with the number of coils, so that each coil is independently wound in the corresponding winding area of ​​the magnetic core.

[0025] like Figure 2 As shown, coils 1 to N can be wound in parallel independently, with no overlap between the coils. Both ends of each coil are directly connected to the drive circuit. All coils have the same number of turns and length to ensure the consistency of the electrical parameters of each coil and thus achieve phase consistency of the current signals of each coil to obtain the best magnetic field synthesis effect.

[0026] The N coils can also be wound in parallel on the magnetic core in an overlapping manner. Specifically, a winding area for winding the coils in parallel in an alternating manner is provided on the magnetic core, and the N coils are wound in parallel from one end of the winding area to the other end of the winding area.

[0027] like Figure 3 As shown, an interlaced winding method is used, and multiple coils are alternately wound on the magnetic core. Compared with the advantage of independent parallel winding, it can ensure the best effective magnetic permeability of the magnetic core.

[0028] Each winding coil can be wound with different cables such as single-core enameled wire, multi-strand excitation wire, etc. according to the communication frequency, meeting the requirements for the antenna in various communication scenarios.

[0029] In order to ensure strong ground penetration, the communication frequency is generally not more than 100kHz. When designing the antenna, you can choose MnZn ferrite materials with good low-frequency response performance, high magnetic permeability and good temperature characteristics as the magnetic core, such as CH5K, CH7K, etc., whose material magnetic permeability is often above 5000. Due to the limited length of the cylindrical magnetic core, it is equivalent to the magnetic circuit with air gap being affected by the demagnetization field. Its effective magnetic permeability is less than the material magnetic permeability and only depends on the overall physical size of the coil and the magnetic core. When the material magnetic permeability is large (often greater than 1000), its effective magnetic permeability μ c The calculation formula can be approximately expressed as:

[0030] μ c =1 / N d

[0031] In the formula, m is the ratio of the length to diameter of the core. When a core material with a magnetic permeability of 5000 is used and the ratio of the length to diameter of the core is greater than 10, the effective magnetic permeability μ of the core is cIt can be more than 30. The cross-sectional area of ​​the magnetic core determines the maximum diameter of the antenna. On the basis of ensuring that the aspect ratio meets the higher effective magnetic permeability, the cross-sectional area of ​​the magnetic core should be increased to increase the magnetic moment of the transmitting magnetic antenna. In the embodiment of this case, a magnetic core with a diameter greater than 20 mm can be selected.

[0032] In the embodiment of this case, based on the theoretical model of magnetic antenna, through the design of high magnetic permeability, large aspect ratio magnetic core structure and optimization of distributed array coil parameters, a parallel multi-coil magnetic antenna with densely wound magnetic core is used to meet the requirements of antenna application deployment of miniaturized portable magnetic communication equipment.

[0033] Furthermore, the above-mentioned parallel multi-coil magnetic antenna structure can be applied to a magnetic communication transmitting antenna, and a through-the-earth magnetic communication system is provided for communication between a ground through-the-earth communication device and an underground through-the-earth communication device. The ground through-the-earth communication device and the underground through-the-earth communication device communicate based on the through-the-earth magnetic communication system. Figure 4 As shown, the geomagnetic communication system includes: a signal detection device for detecting magnetic induction communication signals and a signal transceiver module for processing the detected magnetic induction communication signals and sending / receiving the processed signals, wherein the signal detection device includes a signal transmitting antenna and a signal receiving antenna, and the signal transmitting antenna adopts the above-mentioned magnetic communication transmitting antenna.

[0034] In the geomagnetic communication system, the signal transceiver module involves the transmitting end software control unit, the receiving end software control unit and the transceiver hardware unit, among which the transmitting end software control unit involves channel coding, spread spectrum and carrier modulation technology; the receiving end software design unit involves information despreading, carrier demodulation and channel decoding technology, and the transceiver software control unit involves the communication protocol design of near-field magnetic induction, Bluetooth, proprietary radio frequency, etc. and channel assessment in the direction of channel capacity optimization. The transmitting end hardware unit includes a signal acquisition module, a signal modulation module and a power amplifier circuit module; the receiving end hardware unit includes a resonant filter circuit, a signal amplification module and a signal demodulation module. This case does not improve the above-mentioned signal transceiver module, and existing mature products can be used, which will not be described here one by one.

[0035] Among them, the through-the-earth magnetic communication system may also include: a magnetic positioning module, which is used to predict and output the position of the underground through-the-earth communication equipment through position solution based on the magnetic induction communication signal and the prior signal, and the prior signal is a pilot sequence agreed upon by the underground through-the-earth communication equipment and the ground through-the-earth communication equipment.

[0036] In specific applications, the working frequency can be set according to the current application scenario. For example, if it is to penetrate non-metallic media such as soil, sand and gravel, a higher communication frequency, such as 40kHz, can be used. If it is to penetrate ferromagnetic metal materials such as reinforced concrete, a lower frequency, such as 4kHz, is selected; then the distance parameters are calibrated to support subsequent positioning solutions. The purpose of real-time distance calibration is to eliminate errors caused by system aging, environment and other factors; the next step is to set up, that is, to determine whether the task is to perform positioning or communication, and if necessary, they can be performed simultaneously. If communication, the information is sent first, and then the other party responds and then receives, synchronously demodulates and decodes to obtain the information content sent by the other party; if positioning, the relative position relationship between the transmitted and received signals is inverted according to the three received magnetic field components, and the distance is estimated according to the magnetic field strength, thereby achieving positioning.

[0037] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0038] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A parallel multi-coil magnetic antenna, comprising a magnetic core and a coil wound on the magnetic core, characterized in that: The coil includes N coils wound in parallel, both ends of each coil are provided with connection terminals for connecting to a signal driving circuit, and each coil has the same length and number of winding turns, wherein N is greater than 1.

2. The parallel multi-coil magnetic antenna according to claim 1, characterized in that: The N coils are independently wound in parallel on the magnetic core.

3. The parallel multi-coil magnetic antenna according to claim 2, characterized in that: The magnetic core is provided with a plurality of winding areas for independently winding coils in parallel, the plurality of winding areas are arranged at equal intervals, and the number of the winding areas is consistent with the number of coils, so that each coil is independently wound in the corresponding winding area of ​​the magnetic core.

4. The parallel multi-coil magnetic antenna according to claim 1, characterized in that: The N coils are wound in parallel on the magnetic core in an overlapping manner.

5. The parallel multi-coil magnetic antenna according to claim 4, characterized in that: The magnetic core is provided with a winding area for winding coils in parallel in an alternating manner, and N coils are wound in parallel from one end of the winding area to the other end of the winding area.

6. The parallel multi-coil magnetic antenna according to claim 1, characterized in that: The magnetic core is a MnZn ferrite core.

7. The parallel multi-coil magnetic antenna according to claim 1 or 6, characterized in that: The diameter of the magnetic core is set according to the antenna application scenario.

8. A magnetic communication transmitting antenna, characterized in that: The parallel multi-coil magnetic antenna according to any one of claims 1 to 7 is adopted.

9. A through-the-earth magnetic communication system, used for communication between ground through-the-earth communication equipment and underground through-the-earth communication equipment, characterized in that: The ground through-the-earth communication device and the underground through-the-earth communication device communicate based on a through-the-earth magnetic communication system, and the through-the-earth magnetic communication system includes: a signal detection device for detecting magnetic induction communication signals and a signal transceiver module for processing the detected magnetic induction communication signals and sending / receiving the processed signals, wherein the signal detection device includes a signal transmitting antenna and a signal receiving antenna, and the signal transmitting antenna adopts the magnetic communication transmitting antenna described in claim 8.

10. The geomagnetic communication system according to claim 9, characterized in that: The through-the-earth magnetic communication system also includes: a magnetic positioning module, which is used to predict and output the position of the underground through-the-earth communication device through position solution based on the magnetic induction communication signal and the prior signal, and the prior signal is a pilot sequence agreed upon by the underground through-the-earth communication device and the ground through-the-earth communication device.

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