Magnetic antenna for polar / very low frequency electromagnetic detection and communication and application thereof

Abstract

The invention relates to the technical field of magnetic antennas, in particular to a magnetic antenna for polar / very low frequency electromagnetic detection and communication and application thereof.The magnetic antenna comprises an annular frame, permanent magnets and a coil, the permanent magnets are evenly distributed in the annular frame to form a permanent magnet array, the permanent magnet array is an annular Halbach array, and the coil is arranged in the annular frame; a gap is reserved between every two adjacent permanent magnets in the permanent magnet array, and the permanent magnets are arranged at a preset interval angle in the magnetization direction of every two adjacent permanent magnets in the annular direction of the annular frame; the coils are wound on each permanent magnet, all the coils are connected with an external power supply after being connected into the shunt in parallel, and the shunt is used for adjusting the magnitude and phase of current fed into the coils so as to adjust the radiation range of the magnetic antenna. By introducing the Halbach array into the polar / very low frequency magnetic antenna, the radiation efficiency of the antenna is improved to the maximum extent under the condition that the volume is limited, so that the practical application feasibility of the polar / very low frequency magnetic antenna is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic antennas, and in particular to a magnetic antenna for extreme / very low frequency electromagnetic detection and communication and applications thereof. Background Art

[0002] Extremely low frequency (ELF) magnetic antennas play a key role in several important areas, such as underwater vehicle communications, oil pipeline detection and positioning, medical diagnostics, and non-destructive testing. In these applications, extreme / very low frequency (ELF) electromagnetic waves offer strong penetration and minimal attenuation, giving them unique advantages in specific environments. For example, in underwater vehicle communications, ELF / very low frequency (ELF) electromagnetic waves can penetrate hundreds of meters of seawater, providing a reliable means of communication for underwater vehicles. In oil pipeline detection and positioning, ELF / very low frequency (ELF) electromagnetic waves offer excellent penetration and propagation distance, facilitating non-contact pipeline detection and inspection, both above and below ground, especially in complex soil or rock formations. Low-frequency magnetic antennas generate an electromagnetic field near the oil pipeline, detecting changes in the electromagnetic field to determine its location and direction.

[0003] Existing magnetic antennas mainly include coil antennas, capacitor antennas, and permanent magnet arrays. These magnetic antennas usually require large antenna arrays to work effectively. For example, coil antennas are usually made of multiple turns of wire, which is relatively large in size. In order to generate a sufficiently strong electromagnetic field, large currents are usually required to pass through them. Capacitor antennas, on the other hand, require large parallel plates or metal conductors to form an effective electric field area. As for permanent magnet arrays, although their structure is relatively compact, the magnetic field strength they generate is limited and their adjustment flexibility is insufficient. The common disadvantage of these devices is that they are relatively large in size and weight, especially when used in mobile or portable devices, which will significantly increase the overall weight and volume of the system. In addition, due to their low radiation efficiency, even if these devices consume a lot of power, the electromagnetic field strength and coverage generated are still limited, making it difficult to meet the needs of certain applications. Therefore, under the same power input, traditional devices often find it difficult to achieve ideal radiation effects, limiting their scope of practical application.

[0004] In recent years, with the advancement of new magnetic field design technologies, some optimization solutions have significantly improved the performance of magnetic antennas. For example, the Halbach array design can achieve higher magnetic field strength in a small volume by rationally distributing the magnetic field, while effectively suppressing unnecessary interference from the surrounding environment, thereby improving the stability and reliability of the device. Compared with traditional antennas, this array has obvious advantages in application scenarios with limited volume. Moreover, the application of this array is mainly concentrated in the generation of static magnetic fields, such as magnetic levitation systems, particle accelerators, and high-efficiency motors. In these scenarios, the array improves system performance by optimizing the magnetic field distribution and demonstrates excellent operating efficiency. However, in terms of the generation of dynamic electromagnetic fields, related research and applications are still in the early stages. Currently, the generation of dynamic electromagnetic fields generally relies on traditional coil or capacitive antenna technologies. Although these technologies are mature, they cannot meet specific requirements in terms of certain performance indicators.

[0005] Therefore, it is necessary to provide a magnetic antenna for extreme / very low frequency electromagnetic detection and communication and its application to solve the above problems. Summary of the Invention

[0006] To address the problem that the current generation of dynamic electromagnetic fields generally relies on traditional coil or capacitive antenna technologies, which, although mature, cannot meet specific requirements in terms of certain performance indicators, the present invention provides a magnetic antenna for extreme / very low frequency electromagnetic detection and communication and its application to solve the existing problem.

[0007] A first aspect of the present invention provides a magnetic antenna for extreme / very low frequency electromagnetic detection and communication, which adopts the following technical solution, including: Ring frame; A plurality of permanent magnets are evenly distributed in an annular frame to form a permanent magnet array, the permanent magnet array being an annular Halbach array, and a gap is left between two adjacent permanent magnets in the permanent magnet array; wherein the permanent magnet array comprises: four first permanent magnets, four second permanent magnets, and eight third permanent magnets; the four first permanent magnets are evenly distributed in the annular frame, and the magnetization direction of the first permanent magnets is radially inward of the annular frame; the second permanent magnet is arranged between every two first permanent magnets, and the magnetization direction of the four second permanent magnets is radially outward of the annular frame; the third permanent magnet is arranged between adjacent second permanent magnets and second permanent magnets, and the magnetization direction of the third permanent magnet is along the tangential direction of the annular frame, and the magnetization direction of one of the two adjacent third permanent magnets is the clockwise tangential direction of the annular frame, and the magnetization direction of the other third permanent magnet is the counterclockwise tangential direction of the annular frame; And a coil is wound around each permanent magnet, and all the coils are connected in parallel to a shunt and then connected to an external power supply. The shunt is used to adjust the magnitude and phase of the current fed into the coil to adjust the radiation range of the magnetic antenna.

[0008] According to a further technical solution of the present invention, the annular frame is made of polycarbonate, nylon or polypropylene.

[0009] According to a further technical solution of the present invention, the permanent magnet is a neodymium iron boron magnet.

[0010] According to a further technical solution of the present invention, the annular frame includes an upper annular shell and a lower annular shell, and the upper annular shell and the lower annular shell are buckled and connected by a snap-fit ​​structure.

[0011] According to a further technical solution of the present invention, the permanent magnet and the coil thereon form a radiation unit, and mounting grooves corresponding to the radiation unit are provided on the upper annular shell and the lower annular shell.

[0012] According to a further technical solution of the present invention, the external power supply is an external power supply with adjustable output frequency, and the output frequency is 0.1 Hz to 1 kHz.

[0013] The second aspect of the present invention provides an embodiment of the application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in cross-medium communication. The magnetic antenna provided by the first aspect of the present invention is mounted on an above-water platform, and a magnetic receiver is mounted on an underwater platform. The above-water platform transmits the output command to the magnetic receiver of the underwater platform through the magnetic field signal radiated by the magnetic antenna.

[0014] The third aspect of the present invention provides an embodiment of the application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in cross-medium communication. The magnetic antenna provided by the first aspect of the present invention is mounted on an underwater platform, and a magnetic receiver is mounted on the surface platform. The underwater platform transmits the output command to the magnetic receiver of the surface platform through the magnetic field signal radiated by the magnetic antenna.

[0015] The fourth aspect of the present invention provides an embodiment of the application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in the detection of buried objects on the seabed. The magnetic antenna provided by the first aspect of the present invention is mounted on an underwater vehicle, and a magnetic receiver is mounted on the underwater vehicle. The electromagnetic waves generated by the magnetic antenna are radiated through seawater and buried media to excite a secondary field on the buried objects on the seabed. The magnetic receiver receives the corresponding secondary field signal for analysis and identification of the buried objects on the seabed.

[0016] The fifth aspect of the present invention provides an embodiment of the application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in pipeline detection. The magnetic antenna provided by the first aspect of the present invention is mounted on a probe. When the probe is extended into the rescue well pipeline, the electromagnetic waves generated by the magnetic antenna hit the inner wall of the rescue well pipeline to generate an induced electromagnetic field. The sensor in the probe receives the induced electromagnetic field and determines the direction and distance of the oil pipeline in the accident well based on the changes in the induced electromagnetic field.

[0017] The beneficial effects of the present invention are: 1. By designing the permanent magnets of the magnetic antenna in a circular Halbach arrangement and placing coils on the permanent magnets, the permanent magnets and the coils formed a radiating unit. All coils are connected to an external power supply via shunts, which precisely control the magnitude and phase of the coil current in each radiating unit. Leveraging the unique magnetic field characteristics of this array, enhanced electromagnetic radiation efficiency is achieved in the extremely low frequency range. By rationally optimizing the permanent magnet arrangement and magnetic field distribution, this array effectively enhances the magnetic field outside the permanent magnet array while weakening the magnetic field inside the permanent magnet array, thereby improving the performance and compactness of the entire system, enhancing the concentration and directionality of electromagnetic radiation, and effectively generating a strong electromagnetic radiation field even in the low frequency band. This invention is suitable for various extremely low frequency electromagnetic radiation applications, such as oil and gas pipeline inspection, remote communications, and magnetic field detection. Specifically, by introducing the concept of the Halbach array into an extremely low frequency / very low frequency magnetic antenna, the present invention maximizes the antenna radiation efficiency within a limited space, thereby enhancing the practical application feasibility of extremely low frequency magnetic antennas.

[0018] 2. The magnetic antenna's feed scheme utilizes an independent feeder structure design, connecting the coils to an external power supply via a shunt. The shunt effectively directs the current output from the external power supply to each coil, controlling the current magnitude and phase of the coils to ensure the stability and consistency of electromagnetic radiation from each radiating element. The feeder layout fully considers the structural characteristics of the magnetic array, ensuring balanced current distribution between coils and achieving more efficient electromagnetic radiation conversion and transmission. This design significantly improves the system's radiation performance in the extremely low frequency range.

[0019] 3. The permanent magnet array is surrounded by a ring frame made of high-strength, low-conductivity engineering plastics (polycarbonate, nylon, or polypropylene). Neodymium iron boron magnets are used as the permanent magnet material. The coil structure and winding method optimize the magnetic field output. This series of designs improves the performance of the magnetic antenna while also providing excellent heat resistance and mechanical stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 Schematic diagram of the structure of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication according to the present invention; Figure 2is a magnetization direction diagram of the permanent magnet array of the magnetic antenna in an embodiment of the present invention; Figure 3 In the embodiment of the present invention, Figure 2 The radiation diagram of the magnetic antenna designed with a permanent magnet array is shown; Figure 4 Schematic diagram of a radiation unit formed by winding a coil around a permanent magnet in an embodiment of the present invention; Figure 5 is the magnetization direction diagram of the existing permanent magnet array; Figure 6 for Figure 5 The permanent magnet array and Figure 2 The survey line diagram of the magnetic field value of the magnetic antenna corresponding to the permanent magnet array at 10m; Figure 7 for Figure 5 The permanent magnet array and Figure 2 Comparison diagram of magnetic field simulation of the magnetic antenna corresponding to the permanent magnet array at a 10m survey line; Figure 8 Schematic diagram of the magnetic antenna applied to air-to-sea cross-medium communication in an embodiment of the present invention; Figure 9 Schematic diagram of the magnetic antenna applied to sea-to-air cross-medium communication in an embodiment of the present invention; Figure 10 Schematic diagram of a magnetic antenna used for detecting buried objects on the seabed according to an embodiment of the present invention; Figure 11 Schematic diagram of the application of a magnetic antenna to active oil pipeline detection in an embodiment of the present invention.

[0022] In the figure: 1. Ring frame; 2. Radiating unit. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0024] The present invention provides an embodiment of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication. The purpose of this embodiment is to provide a magnetic antenna that can flexibly control the dynamic magnetic field within a certain range to meet the needs of different scenarios, and can generate a high-intensity, stable extremely low frequency electromagnetic field in all directions to reduce magnetic field leakage. To achieve the above technical objectives, as Figure 1As shown, this embodiment specifically includes: an annular frame 1, a coil and a plurality of permanent magnets; the plurality of permanent magnets are evenly distributed in the annular frame 1 to form a Halbach permanent magnet array, and a gap is left between two adjacent permanent magnets in the permanent magnet array, and the magnetization directions of every two adjacent permanent magnets along the circumferential direction of the annular frame 1 are arranged at a preset interval angle; a coil is wound around each permanent magnet, and all the coils are connected in parallel to a shunt and then to an external power supply, and the shunt is used to achieve precise control of the magnitude and phase of the coil current, thereby controlling the radiation range of the magnetic antenna.

[0025] For example, Figure 2 As shown, in a specific embodiment, the spacing angle in the Halbach permanent magnet array is 90°, and the specific permanent magnet array includes: four first permanent magnets, four second permanent magnets and eight third permanent magnets; wherein, the four first permanent magnets are evenly distributed in the annular frame 1, and the magnetization direction of the first permanent magnets is radially inward of the annular frame 1; the second permanent magnet is arranged between every two first permanent magnets, and the magnetization direction of the four second permanent magnets is radially outward of the annular frame 1; the third permanent magnet is arranged between adjacent second permanent magnets and second permanent magnets, and the magnetization direction of the third permanent magnet is along the tangential direction of the annular frame 1, and the magnetization direction of one of the two adjacent third permanent magnets is the clockwise tangential direction of the annular frame 1, and the magnetization direction of the other third permanent magnet is the counterclockwise tangential direction of the annular frame 1; wherein, in this embodiment, the size of each permanent magnet depends on the total annular diameter of the permanent magnet array, the number of permanent magnets and the magnetic field strength to be achieved. In this embodiment, the diameter of the permanent magnet array is designed to be 0.5m, and the length, width and height of each permanent magnet are the same, which are 0.02m × 0.02m × 0.02m; Figure 4 As shown, the coil is wound with high-purity copper wire, which has low resistance, high conductivity and good thermal stability. The choice of copper wire diameter depends on the current size and resistance requirements. The coil of each permanent magnet is wound independently and tightly attached to the surface of the permanent magnet. The length and number of turns of the coil are optimized according to the size of the permanent magnet. All coils are connected in parallel, and each coil is connected in parallel to the shunt at the same time. The shunt is used to achieve precise control of the coil current and phase, that is, Figure 3 As shown, by optimizing the magnetization direction of the permanent magnet, the magnetization direction of the permanent magnet is made to present a pattern of bottom right top left after power is applied, and the permanent magnet is arranged in a circle around the annular frame 1 according to the pattern of bottom right top left, so that the magnetic field distribution is more concentrated and uniform, and a stronger magnetic field radiation effect can be achieved in the specified area.

[0026] It should be noted that Figure 2The top permanent magnet is the first permanent magnet. Going clockwise, the first permanent magnet is the first permanent magnet, magnetized radially inward from the annular frame 1. The second permanent magnet is the third permanent magnet, magnetized clockwise and tangentially to the annular frame 1. The third permanent magnet is the second permanent magnet, magnetized radially outward from the annular frame 1. The fourth permanent magnet is also the third permanent magnet, and all four magnets are magnetized counterclockwise and tangentially to the annular frame 1. This cycle continues in this order, with four permanent magnets forming a complete permanent magnet array of 16 permanent magnets. This design not only generates a strong and uniform magnetic field but also prevents excess magnetic field leakage, thereby improving system efficiency. The permanent magnets are made of neodymium iron boron (NdFeB), a high-performance rare earth permanent magnet material with an extremely high magnetic energy product (energy density) that can generate a strong magnetic field at room temperature. The application of NdFeB magnets provides the entire system with a strong magnetic field output capability, while its miniaturization characteristics meet the requirements of compact equipment design.

[0027] For example, in a specific embodiment, in order to enhance the stability of the structure and provide protection for the permanent magnet array, the annular frame 1 of this embodiment adopts a high-strength, low-conductivity engineering plastic material, such as polycarbonate (PC), nylon or polypropylene (PP). The annular frame 1 includes an upper annular shell and a lower annular shell, which are connected by a snap-on structure. This design makes the device detachable, which is convenient for maintenance or replacement of components when necessary. This structural design can not only effectively improve the overall stability of the device, but also provide reliable protection during operation, ensuring that the permanent magnet and coil work normally in a high temperature environment, while facilitating operation and maintenance. Secondly, Figure 4 As shown, the permanent magnet and the coil thereon form a radiation unit 2, and mounting grooves corresponding to the radiation unit 2 are provided on the upper annular shell and the lower annular shell. The radiation unit 2 is installed in the annular frame 1 through the mounting grooves to ensure that they can be firmly fixed in the frame to avoid loosening or displacement.

[0028] In this embodiment, the material of annular frame 1 must possess excellent heat resistance, as the magnetic antenna may generate a certain amount of heat during operation. Polycarbonate has the best heat resistance of the three materials, so this embodiment uses polycarbonate as the material for annular frame 1. The wall thickness of annular frame 1 is designed to be 10 mm, which ensures sufficient mechanical strength without significantly increasing the weight of the device.

[0029] For example, in a specific embodiment, to meet the needs of different application scenarios, the external power supply is an external power supply with adjustable output frequency, and the output frequency is 0.1 Hz to 1 kHz.

[0030] The following describes this embodiment with reference to specific simulation data: like Figure 5 As shown, the magnetization direction of the conventional antenna is usually radially outward, and the magnetization direction of each permanent magnet is arranged radially outward, and these permanent magnets are arranged in an array to form a ring array consisting of 16 permanent magnets, so the present invention is as shown in FIG. Figure 2 Compared with the permanent magnet array shown in FIG. 1 and the existing permanent magnet array, the permanent magnet array of the magnetic antenna of the present invention has a different magnetization direction from the traditional permanent magnet array. Figure 6 As shown in the figure, the red measuring line of the magnetic antennas of the two permanent magnet arrays is set at 10 meters, in order to measure and compare the magnetic field values ​​generated by the two magnetic antennas at this distance. Through this measurement, a simulation comparison of the magnetic field magnitude of the magnetic antennas of the two different designs of permanent magnet arrays at the 10-meter measuring line under the same environmental conditions is obtained as shown in the figure below. Figure 7 As shown. In this experiment, the magnetic antenna was simulated at an excitation frequency of 10 Hz, and the magnetic field strength at 10 meters was measured. The simulation results show that the magnetic field peak value of the magnetic antenna based on the permanent magnet array of the present invention at 10 meters is 4nT, and the minimum value is 1.5nT, while the magnetic field value of the magnetic antenna with the existing permanent magnet array is very small under the same conditions, almost 0nT. This comparison result intuitively shows that the magnetic antenna with the proposed permanent magnet array arrangement structure can generate a stronger magnetic field at the same distance. This design has significant advantages in the intensity and distribution of the magnetic field, especially at a longer distance, the magnetic field decays more slowly and can cover a wider range; and the magnetic antenna based on the special magnetic field arrangement structure is not only superior to the traditional design in magnetic field intensity, but also shows better performance in propagation distance.

[0031] An embodiment of the application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in cross-medium communication of the present invention is as follows: Figure 8 As shown, the magnetic antenna of this embodiment is mounted on a surface platform (aircraft or ship), and a magnetic receiver is mounted on an underwater platform (underwater UUV). The surface platform transmits the output command to the magnetic receiver of the underwater platform through the magnetic field signal radiated by the magnetic antenna.

[0032] An embodiment of the application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in cross-medium communication of the present invention is as follows: Figure 9 As shown, the magnetic antenna of this embodiment is mounted on an underwater platform (underwater UUV), and a magnetic receiver is mounted on an above-water platform (aircraft or ship). The underwater platform transmits the output command to the magnetic receiver of the above-water platform through the magnetic field signal radiated by the magnetic antenna.

[0033] An embodiment of the application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in detecting buried objects on the seabed of the present invention is as follows: Figure 10 As shown, the magnetic antenna of this embodiment is mounted on an underwater vehicle (underwater UUV), and a magnetic receiver is mounted on the underwater vehicle (underwater UUV). The electromagnetic waves generated by the magnetic antenna are radiated through seawater and buried media to excite a secondary field on objects buried on the seabed. The magnetic receiver receives the corresponding secondary field signal to analyze and identify the buried objects on the seabed.

[0034] An embodiment of the application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in pipeline detection of the present invention is as follows: Figure 11 As shown, the magnetic antenna of this embodiment is mounted on a probe, and an external power supply generates current through a cable and inputs it into the magnetic antenna. When the probe is extended into the rescue well pipeline, the electromagnetic waves generated by the magnetic antenna hit the wall of the oil pipe in the accident well to generate an induced electromagnetic field. The sensor in the probe receives the secondary induced electromagnetic field generated by the oil pipe in the accident well, and determines the direction and distance of the oil pipe in the accident well based on the changes in the secondary induced electromagnetic field. It should be noted that the low-frequency electromagnetic waves emitted by the magnetic antenna pass through most non-conductive media. The oil pipe is usually made of metal material and has high conductivity. When the extremely low-frequency electromagnetic waves encounter the oil pipe during propagation, an induced magnetic field will be generated around it.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetic antenna for extreme / very low frequency electromagnetic detection and communication, characterized in that: include: Ring frame; A plurality of permanent magnets are evenly distributed in an annular frame to form a permanent magnet array, the permanent magnet array being an annular Halbach array, and a spacing being left between two adjacent permanent magnets in the permanent magnet array, wherein the permanent magnet array comprises: four first permanent magnets, four second permanent magnets, and eight third permanent magnets; the four first permanent magnets are evenly distributed in the annular frame, and the magnetization direction of the first permanent magnets is radially inward of the annular frame; the second permanent magnet is arranged between every two first permanent magnets, and the magnetization direction of the four second permanent magnets is radially outward of the annular frame; the third permanent magnet is arranged between adjacent second permanent magnets and second permanent magnets, and the magnetization direction of the third permanent magnet is along the tangential direction of the annular frame, the magnetization direction of one of the two adjacent third permanent magnets is the clockwise tangential direction of the annular frame, and the magnetization direction of the other third permanent magnet is the counterclockwise tangential direction of the annular frame; And a coil is wound around each permanent magnet, and all the coils are connected in parallel to a shunt and then connected to an external power supply. The shunt is used to adjust the magnitude and phase of the current fed into the coil to adjust the radiation range of the magnetic antenna.

2. A magnetic antenna for extreme / very low frequency electromagnetic detection and communication according to claim 1, characterized in that: Ring frames are available in polycarbonate, nylon or polypropylene.

3. A magnetic antenna for extreme / very low frequency electromagnetic detection and communication according to claim 1, characterized in that: The permanent magnet is a neodymium iron boron magnet.

4. A magnetic antenna for extreme / very low frequency electromagnetic detection and communication according to claim 1, characterized in that: The annular frame comprises an upper annular shell and a lower annular shell, and the upper annular shell and the lower annular shell are buckled and connected through a snap-fit ​​structure.

5. A magnetic antenna for extreme / very low frequency electromagnetic detection and communication according to claim 4, characterized in that: The permanent magnet and the coil thereon form a radiation unit, and mounting grooves corresponding to the radiation unit are provided on the upper annular shell and the lower annular shell.

6. The magnetic antenna for extreme / very low frequency electromagnetic detection and communication according to claim 1, characterized in that: The external power supply is an external power supply with adjustable output frequency, and the output frequency is 0.1 Hz to 1 kHz.

7. Application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in cross-medium communication, characterized in that: The magnetic antenna described in any one of claims 1 to 6 is mounted on an above-water platform, and a magnetic receiver is mounted on an underwater platform. The above-water platform transmits the output command to the magnetic receiver of the underwater platform through the magnetic field signal radiated by the magnetic antenna.

8. Application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in cross-medium communication, characterized in that: The magnetic antenna described in any one of claims 1 to 6 is mounted on an underwater platform, and a magnetic receiver is mounted on the surface platform. The underwater platform transmits the output command to the magnetic receiver on the surface platform through the magnetic field signal radiated by the magnetic antenna.

9. Application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in detecting buried objects on the seabed, characterized in that: The magnetic antenna described in any one of claims 1 to 6 is mounted on an underwater vehicle, and a magnetic receiver is mounted on the underwater vehicle. The electromagnetic waves generated by the magnetic antenna are radiated through seawater and buried media to excite a secondary field on an object buried on the seabed. The magnetic receiver receives the corresponding secondary field signal to analyze and identify the buried object on the seabed.

10. Application of a magnetic antenna for extreme / very low frequency electromagnetic detection and communication in pipeline detection, characterized in that: The magnetic antenna described in any one of claims 1 to 6 is mounted on a probe tube. When the probe tube is extended into the rescue well pipe, the electromagnetic waves generated by the magnetic antenna hit the inner wall of the rescue well pipe to generate an induced electromagnetic field. The sensor in the probe tube receives the induced electromagnetic field and determines the direction and distance of the oil pipeline in the accident well based on the changes in the induced electromagnetic field.

Images