Antenna structure and transient electromagnetic detection device

Abstract

An antenna structure and a transient electromagnetic detection device, the antenna structure comprising a main emission wireframe and auxiliary emission wireframe groups, each auxiliary emission wireframe group comprising two auxiliary emission wireframes. The main emission wireframe is used for generating a first magnetic field in a first area and a second area on two sides thereof, and the auxiliary emission wireframe group is used for generating a second magnetic field in the first area in the same direction as the first magnetic field and generating a third magnetic field in the second area in the opposite direction to the first magnetic field. Namely, the main emission wireframe and the auxiliary emission wireframe group can superpose the magnetic induction intensity in the same direction in a first area in the detection direction and counteract the magnetic induction intensity in the reverse direction in a second area in the non-detection direction, so that a primary magnetic field generated by the antenna structure can be obviously weakened on one side of the non-detection area; the effect of directionally emitting the excitation magnetic field for the detection area is achieved, and therefore the low-resistance abnormal illusion is recognized in the apparent resistivity inversion result.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of detection equipment, and specifically to an antenna structure and a transient electromagnetic detection device. Background Art

[0002] The transient electromagnetic method (TEM) is a time-domain artificial source electromagnetic detection method. Its working principle is mainly to use the physical property differences of underground media in electrical conductivity and magnetic permeability to achieve geophysical exploration.

[0003] The detection process of transient electromagnetic method can be divided into three stages: transmission, induction and reception: disconnect the stable current loaded in the transmitting antenna, and the stable primary magnetic field in the surrounding space disappears; due to the drastic change of the primary magnetic field, an induced eddy current will be stimulated in the geological body in the detection area to maintain the original magnetic field, and a secondary magnetic field will be generated at this time; the induced current decays over time due to the heat loss of the medium, and the receiving antenna is used to observe the corresponding attenuation process of the secondary magnetic field, and the electrical distribution of the geological body in the detection area is inferred based on the received induced electromotive force data, and the resistance anomaly is qualitatively and quantitatively evaluated.

[0004] However, when the transient electromagnetic method is used in the scenario of full-space detection, the received induced electromotive force data is the superposition of the electromagnetic response signals generated by the geological body in the detection area and the interference body in the non-detection area. For example, the metal body near the antenna system is a common source of electromagnetic interference, which will cause the appearance of low-resistance anomaly in the apparent resistivity inversion result. Summary of the invention

[0005] The embodiment of the present application provides an antenna structure for realizing the directional emission of an excitation magnetic field by the antenna in a detection area. The embodiment of the present application also provides a corresponding transient electromagnetic detection device.

[0006] According to a first aspect of the present application, an antenna structure is provided, which includes at least one main transmitting wire frame and at least one auxiliary transmitting wire frame group, wherein each of the at least one auxiliary transmitting wire frame group includes two auxiliary transmitting wire frames; at least one main transmitting wire frame is used to generate a first magnetic field in a first area and a second area, and the two sides of at least one main transmitting wire frame are the first area and the second area respectively; at least one auxiliary transmitting wire frame group is used to generate a second magnetic field in the first area with the same direction as the first magnetic field, and generate a third magnetic field in the second area with the opposite direction to the first magnetic field.

[0007] In the present application, the antenna structure can be applied to a transient electromagnetic detection device, the first area is the detection area of ​​the antenna structure, that is, the target area that the transient electromagnetic detection device needs to detect, and the second area is the non-detection area.

[0008] In the present application, the primary magnetic field on both sides of the main transmitting wire frame is symmetrically distributed relative to the plane where the transmitting wire frame is located. In the full space environment, such a primary magnetic field will cover the detection area and the non-detection area on both sides of the antenna at the same time, and cannot reflect the difference in the orientation of the resistance anomaly. An auxiliary transmitting wire frame group is set on the basis of the main transmitting wire frame, and the magnetic induction intensity of the space around the main transmitting wire frame and the two auxiliary transmitting wire frames can be calculated together with the formula. In the first area, the main transmitting wire frame and the two auxiliary transmitting wire frames generate magnetic fields in the same direction, and in the second area, the two generate magnetic fields in opposite directions, that is, the composite magnetic field is superimposed in the same direction in the first area, and the magnetic induction intensity increases, and in the second area, it is reversely offset, and the magnetic induction intensity decreases. As a result, the primary magnetic field generated by the directional transmitting antenna can be significantly weakened on one side of the non-detection area, so as to achieve the effect of directional emission excitation magnetic field for the detection area.

[0009] In the first aspect, the antenna structure includes a main transmitting wire frame and an auxiliary transmitting wire frame group, wherein each auxiliary transmitting wire frame group includes two auxiliary transmitting wire frames. The main transmitting wire frame is used to generate a first magnetic field in a first area and a second area on both sides thereof, and the auxiliary transmitting wire frame group is used to generate a second magnetic field in the first area with the same direction as the first magnetic field, and a third magnetic field in the second area with the opposite direction to the first magnetic field, that is, the main transmitting wire frame and the auxiliary transmitting wire frame group can superimpose the magnetic induction intensity in the same direction in the first area located in the detection direction, and reversely cancel the magnetic induction intensity in the second area located in the non-detection direction, thereby significantly weakening the primary magnetic field generated by the antenna structure on one side of the non-detection area, achieving the effect of directional emission of the excitation magnetic field for the detection area, thereby realizing the identification of the low-resistance anomaly illusion in the apparent resistivity inversion result.

[0010] In a possible implementation manner of the first aspect, the antenna structure further includes at least one receiving wire frame, and the at least one receiving wire frame is located on a zero magnetic flux plane of the second magnetic field or the third magnetic field.

[0011] In this possible implementation, the receiving wire frames are all located at the zero flux plane of the auxiliary transmitting antenna, and there is only mutual inductance between the main transmitting antenna and the receiving antenna. After eliminating the mutual inductance between the auxiliary transmitting antenna and the receiving antenna, the impact of the primary magnetic field generated by the directional transmitting antenna on the receiving antenna is significantly reduced, and the detection blind area is significantly reduced.

[0012] In a possible implementation manner of the first aspect, an angle between a normal direction of at least one receiving wireframe and a normal direction of at least one main transmitting wireframe is 0 degrees or 90 degrees.

[0013] In this possible implementation, the receiving wire frame is parallel or perpendicular to the main transmitting wire frame, so that the receiving wire frame can be located on the zero magnetic flux plane of the second magnetic field or the third magnetic field, thereby improving the feasibility of the solution.

[0014] In a possible implementation manner of the first aspect, the number of the at least one auxiliary transmission wireframe group is an even number.

[0015] In this possible implementation, when the number of auxiliary transmitting wireframe groups is an even number, the auxiliary transmitting antenna can be prevented from affecting the magnetic field in the Y-axis direction and the Z-axis direction.

[0016] In a possible implementation manner of the first aspect, at least one main transmitting wire frame is perpendicular to at least one auxiliary transmitting wire frame group.

[0017] In this possible implementation, the main transmitting wire frame is perpendicular to the auxiliary transmitting wire frame group, so that the second magnetic field and the third magnetic field generated by the auxiliary transmitting wire frame group are adapted to the direction of the first magnetic field, thereby increasing the magnetic field strength in the first area and reducing the magnetic field strength in the second area.

[0018] In a possible implementation manner of the first aspect, in at least one auxiliary emission wireframe group, an angle between normal directions of any two auxiliary emission wireframe groups is greater than 0 degree and less than or equal to 90 degrees.

[0019] In this possible implementation, any two auxiliary transmission wireframe groups are perpendicular to each other, or the angle between them may be less than 90 degrees, which improves the feasibility of the solution.

[0020] In a possible implementation manner of the first aspect, the two auxiliary transmitting wire frames are parallel to each other and maintain a first preset distance between them.

[0021] In this possible implementation, when the two auxiliary transmitting wire frames are parallel to each other and maintain a first preset distance between them, the overall assembly and manufacturing of the antenna structure are facilitated, thereby improving the feasibility of the solution.

[0022] In a possible implementation manner of the first aspect, the first preset distance is greater than 0 and less than or equal to a side length or a diameter of any one of the two auxiliary transmission wire frames.

[0023] In this possible implementation, the first preset distance is specifically greater than 0 and less than or equal to the side length or diameter of any one of the two auxiliary transmission wire frames, which improves the feasibility of the solution.

[0024] In a possible implementation manner of the first aspect, the two auxiliary transmitting wire frames have the same size and the same number of coil turns.

[0025] In this possible implementation, the sizes of the two auxiliary transmitting wire frames and the number of turns of the coils are the same, which facilitates the overall assembly and manufacturing of the antenna structure and improves the feasibility of the solution.

[0026] In a possible implementation manner of the first aspect, the coils of the two auxiliary transmitting wire frames are wound in the same direction and the currents are in opposite directions; or, the coils of the two auxiliary transmitting wire frames are wound in opposite directions and the currents are in the same direction.

[0027] In this possible implementation, in order to make the auxiliary transmitting wire frame group generate two equivalent magnetic fields in opposite directions, the coils can be wound in the same direction and the currents can be wound in opposite directions, or the coils can be wound in opposite directions and the currents can be wound in the same direction, thereby improving the feasibility of the solution.

[0028] In a possible implementation manner of the first aspect, the antenna structure further includes an insulating bracket, and the insulating bracket is used to fix at least one main transmitting wire frame and at least one auxiliary transmitting wire frame group.

[0029] In this possible implementation, an insulating bracket is used to fix the antenna structure, which improves the feasibility of the solution.

[0030] In a possible implementation manner of the first aspect, the insulating support is further used to adjust positions of at least one main transmitting wire frame and at least one auxiliary transmitting wire frame group.

[0031] In this possible implementation, an insulating bracket is used to fix the antenna structure, which has the function of moving and rotating each transmitting wire frame and receiving wire frame. Therefore, the structure of the directional transmitting antenna can be designed according to the construction environment. At the same time, the position of the receiving antenna can be adjusted according to the actual primary magnetic field, and each receiving wire frame can be adjusted to the zero flux plane position, thereby improving the adaptability of the antenna structure.

[0032] In a possible implementation manner of the first aspect, shapes of the at least one main transmitting wireframe and the two auxiliary transmitting wireframes include a rectangle, a trapezoid, a circle, a polygon, and a spiral.

[0033] In this possible implementation, the main transmitting wireframe and the auxiliary transmitting wireframe may have various shapes, thereby improving the feasibility of the solution.

[0034] In a possible implementation manner of the first aspect, at least one main transmitting wire frame and at least one receiving wire frame have the same size and fit each other.

[0035] In this possible implementation, the antenna structure can be arranged as an observation device commonly used in transient electromagnetic detection, such as an overlapping loop, which improves the feasibility of the solution.

[0036] In a possible implementation manner of the first aspect, a size of at least one main transmitting wireframe is larger than that of at least one receiving wireframe, and the at least one main transmitting wireframe is coplanar with the at least one receiving wireframe and their center points coincide with each other.

[0037] In this possible implementation, the antenna structure can be arranged as an observation device commonly used in transient electromagnetic detection, such as a center loop, which improves the feasibility of the solution.

[0038] In a possible implementation manner of the first aspect, at least one main transmitting wire frame is parallel to at least one receiving wire frame and is separated by a second preset distance.

[0039] In this possible implementation, the antenna structure can be arranged as an observation device commonly used in transient electromagnetic detection, such as a dipole device, which improves the feasibility of the solution.

[0040] A second aspect of the present application provides a transient electromagnetic detection device, which includes a transmitter, a host computer, a receiver, and an antenna structure as described in the first aspect or any possible implementation of the first aspect.

[0041] In a possible implementation manner of the second aspect, the transmitter includes multiple interfaces, and the transmitter is connected to the antenna structure through the multiple interfaces.

[0042] In this possible implementation, by cooperating with multiple transmission wire frames of the antenna structure through multiple interfaces of the transmitter, the transmitter not only adapts to different antenna structures, but also can meet the multi-channel requirements of users.

[0043] In an embodiment of the present application, the antenna structure includes a main transmitting wire frame and an auxiliary transmitting wire frame group, wherein each auxiliary transmitting wire frame group includes two auxiliary transmitting wire frames. The main transmitting wire frame is used to generate a first magnetic field in a first area and a second area on both sides thereof, and the auxiliary transmitting wire frame group is used to generate a second magnetic field in the first area with the same direction as the first magnetic field, and a third magnetic field in the second area with the opposite direction to the first magnetic field, that is, the main transmitting wire frame and the auxiliary transmitting wire frame group can superimpose the magnetic induction intensity in the same direction in the first area located in the detection direction, and reversely cancel the magnetic induction intensity in the second area located in the non-detection direction, thereby significantly weakening the primary magnetic field generated by the antenna structure on one side of the non-detection area, achieving the effect of directional emission of the excitation magnetic field for the detection area, thereby realizing the identification of the low-resistance anomaly illusion in the apparent resistivity inversion result. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of a transient electromagnetic detection device;

[0045] Figure 2 and Figure 3 A schematic diagram of a transient electromagnetic detection scenario provided in an embodiment of the present application;

[0046] Figure 4 A schematic diagram of an embodiment of an antenna structure provided in an embodiment of the present application;

[0047] Figure 5A and Figure 5B A schematic diagram of the magnetic field distribution of the main transmitting antenna provided in an embodiment of the present application;

[0048] Figure 5C and Figure 5D A schematic diagram of the magnetic field distribution of the auxiliary transmitting antenna provided in an embodiment of the present application;

[0049] Figure 6 A schematic diagram of an embodiment of a transient electromagnetic detection device provided in an embodiment of the present application;

[0050] Fig. 7A Schematic diagram of apparent resistivity inversion results of conventional antenna structure;

[0051] Figure 7B A schematic diagram of an apparent resistivity inversion result of an antenna structure is provided for an embodiment of the present application;

[0052] Figure 8A-8D Schematic diagrams of other embodiments of the antenna structure provided in the embodiments of the present application;

[0053] Figure 9A-9D Schematic diagrams of other embodiments of the antenna structure provided in the embodiments of the present application;

[0054] Fig.10 A schematic diagram of another embodiment of a transient electromagnetic detection device provided in an embodiment of the present application;

[0055] Fig.11 A schematic diagram of the magnetic field distribution of the transient electromagnetic detection device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0056] The following describes the embodiments of the present application in conjunction with the accompanying drawings. Obviously, the described embodiments are only embodiments of a part of the present application, rather than all embodiments. It is known to those skilled in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0057] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0058] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0059] In addition, in order to better illustrate the present application, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present application.

[0060] The following is an example of the application scenario involved in the embodiments of the present application.

[0061] Transient electromagnetic method (TEM) is a time-domain artificial source electromagnetic detection method. Its working principle is mainly based on the law of electromagnetic induction, and it uses the physical property differences of underground media in electrical conductivity and magnetic permeability to achieve geophysical exploration. Transient electromagnetic detection technology has many advantages, such as high construction efficiency, long detection distance, good coupling with geological bodies, ability to penetrate high-resistance surrounding rocks, extremely sensitive response to low-resistance bodies and no influence from their occurrence. In recent years, it has been widely used in geophysical exploration fields such as mineral resource exploration, water resource exploration, engineering geological survey and geological disaster prediction.

[0062] like Figure 1 As shown in the figure, the transient electromagnetic detection device using the transient electromagnetic method is composed of a host computer, a transmitter, a receiver, a transmitting antenna and a receiving antenna. The transmitting and receiving antennas usually use circular or rectangular planar multi-turn coils, and the antenna system is arranged in the same point loop, separate loop and large fixed source loop. The detection process of the transient electromagnetic method can be divided into three stages: transmission, induction and reception: disconnect the stable current loaded in the transmitting antenna, and the stable primary magnetic field in the surrounding space disappears; due to the drastic change of the primary magnetic field, an induced eddy current will be stimulated in the geological body in the detection area to maintain the original magnetic field, and a secondary magnetic field will be generated at this time; the induced current decays over time due to the heat loss of the medium, and the receiving antenna is used to observe the corresponding decay process of the secondary magnetic field, and the electrical distribution of the geological body in the detection area is inferred based on the received induced electromotive force data, and the resistance anomaly is qualitatively and quantitatively evaluated.

[0063] In the ground transient electromagnetic detection scenario, the antenna system is usually laid horizontally on the surface, and the transmitting magnetic moment is controlled by adjusting the size and current intensity of the transmitting antenna to perform deep half-space detection of underground media. In underground transient electromagnetic detection scenarios such as traffic tunnels and coal mine tunnels, the antenna system is usually placed vertically on the excavation face, where the size of the transmitting antenna is limited by the construction space, and the intensity of the transmitting current also needs to meet relevant safety standards. The small transmitting magnetic moment limits the effective detection distance of the transient electromagnetic method, and this is full-space detection. The received electromagnetic data is the superposition of the electromagnetic response signals generated by the geological body in the detection area and the interference body in the non-detection area. For example, metal bodies such as anchor nets, rails, and I-beams near the antenna system are common electromagnetic interference sources, which will cause low-resistance anomalies in the apparent resistivity inversion results. How to reduce the impact of this full-space effect on transient electromagnetic detection is an urgent problem to be solved.

[0064] Based on this, the embodiment of the present application provides an antenna structure for realizing the antenna to directional emit an excitation magnetic field in a detection area, and the embodiment of the present application also provides a corresponding transient electromagnetic detection device, which is described in detail below.

[0065] The antenna structure provided in the embodiment of the present application can be applied to Figure 1 The transient electromagnetic detection device shown mainly includes a host computer, a transmitter, a receiver and an antenna structure, wherein a main transmitting antenna and an auxiliary transmitting antenna are combined at the transmitting end of the antenna structure, so that the primary magnetic field can be significantly weakened on one side of the non-detection area, thereby achieving the effect of directional emission of the excitation magnetic field for the detection area. The antenna structure provided in the embodiment of the present application has good applicability in common transient electromagnetic method application scenarios, and can significantly reduce the influence of the full space effect on transient electromagnetic detection.

[0066] like Figure 2 As shown, the antenna structure provided in the embodiment of the present application can be combined with a transient electromagnetic detection device and applied to various underground transient electromagnetic detection scenarios. The antenna structure includes a transmitting antenna T x and receiving antenna R x . In underground excavation projects such as mine tunnels, traffic tunnels and water diversion tunnels, it is necessary to carry out advanced geological forecasting work for water hazards. Usually, the antenna structure of the transient electromagnetic detection device is arranged at the excavation face or in the advance borehole, both of which belong to the full-space environment. At this time, the antenna structure provided in the embodiment of the present application can emit a strong primary magnetic field in the detection direction, and a weaker primary magnetic field is generated on the side of the non-detection area, thereby reducing the influence of the full-space effect, eliminating the low-resistance anomaly illusion in the apparent resistivity inversion result, and can use multiple small-sized transmitting wireframes in a limited construction space to achieve long-distance transient electromagnetic detection.

[0067] like Figure 3 As shown, the antenna structure provided in the embodiment of the present application can also be combined with a transient electromagnetic detection device and applied to an aviation transient electromagnetic detection scenario. The antenna structure includes a transmitting antenna T x and receiving antenna R x It is often difficult to carry out ground detection work in complex terrain conditions such as forests, deserts, Gobi and mountains. Using aircraft such as helicopters or drones as carrier platforms and conducting aerial transient electromagnetic detection through main cables and inclined cables can significantly improve work efficiency.

[0068] The antenna structure provided in the embodiment of the present application is suspended at a certain distance below the aircraft in a flexible connection manner, and other devices are placed in the cabin of the aircraft. The antenna structure provided in the embodiment of the present application can emit a strong primary magnetic field to the underground rock mass, and the metal aircraft above the antenna structure can be covered by a weaker primary magnetic field, thereby reducing the influence of the full space effect and realizing deep and high-accuracy aviation transient electromagnetic detection.

[0069] The antenna structure provided in the embodiment of the present application is described below in conjunction with the above application scenarios.

[0070] like Figure 4 As shown, an embodiment of the present application provides an antenna structure, and an embodiment of the antenna structure includes at least one main transmitting wire frame and at least one auxiliary transmitting wire frame group.

[0071] Among them, each auxiliary transmitting wire frame group in at least one auxiliary transmitting wire frame group includes two auxiliary transmitting wire frames; at least one main transmitting wire frame is used to generate a first magnetic field in a first area and a second area, and the two sides of at least one main transmitting wire frame are the first area and the second area respectively; at least one auxiliary transmitting wire frame group is used to generate a second magnetic field in the first area with the same direction as the first magnetic field, and generate a third magnetic field in the second area with the opposite direction to the first magnetic field.

[0072] Specifically, the antenna structure is applied to Figure 1-Figure 3 The transient electromagnetic detection device and scene shown in the figure, the antenna structure includes a main transmitting antenna and an auxiliary transmitting antenna, the main transmitting antenna includes at least one main transmitting wire frame, the auxiliary transmitting antenna includes at least one auxiliary transmitting wire frame group, and each auxiliary transmitting wire frame group includes two auxiliary transmitting wire frames. The first area is the detection area of ​​the antenna structure, that is, Figure 4 The area where the detection direction is located based on the main transmission line frame shown in the figure is the target area that the transient electromagnetic detection device needs to detect, and the second area is the non-detection area.

[0073] For example, Figure 4 As shown, the main transmitting antenna includes a main transmitting wire frame T x1The auxiliary transmitting antenna includes an auxiliary transmitting wire frame group, the auxiliary transmitting wire frame group includes an auxiliary transmitting wire frame T x2 and T x3 .

[0074] From the superposition principle of vector magnetic field, we know that if a closed loop is divided into several current elements, the magnetic field at any point P (x0, y0, z0) in the surrounding space is the superposition of the magnetic fields generated by all current elements at that point. Then, according to the Biot-Savart law, the magnetic induction intensity B at point P can be expressed as:

[0075]

[0076]

[0077]

[0078] Among them, I is the current intensity in the closed loop, (x, y, z) is the spatial coordinates of a current element, and r is the distance from the current element to point P, that is, μ0 is the magnetic permeability in vacuum, which is 4π×10 -7 T.m.A. -1 .

[0079] According to the above formula, the magnetic induction intensity of the space around the closed loop can be calculated. Taking the main transmitting wire frame as a rectangle as an example, Figure 5A As shown, in the xyz spatial rectangular coordinate system, the main emission wireframe (white part) is located on the yOz plane (i.e., the plane of the y-axis and the z-axis), and its normal coincides with the x-axis, as shown in FIG. Figure 5B As shown, this is the B of the main emission line frame (black part) x The distribution of the components on the xOz section (i.e., the section between the x-axis and the z-axis). Obviously, when a conventional main transmitting wire frame is used as the transmitting antenna of a transient electromagnetic detection device, the primary magnetic field on both sides is symmetrically distributed relative to the plane where the transmitting wire frame is located (the yOz plane at x=0). In a full-space environment, such a primary magnetic field will simultaneously cover the detection area and the non-detection area on both sides of the antenna, and cannot reflect the difference in the orientation of the resistance anomaly.

[0080] like Figure 5C As shown, the two auxiliary emission wireframes (white parts) in the auxiliary emission wireframe group are also rectangular. In the xyz spatial rectangular coordinate system, the two auxiliary emission wireframes are also located on the yOz plane, and their normals are perpendicular to the x-axis, as shown in FIG. Figure 5D As shown, the B of the two auxiliary emission wireframes (black part) xThe distribution of components on the xOz section. The above formula can be used to calculate the magnetic induction intensity of the space around the main transmitting wireframe and the two auxiliary transmitting wireframes. Assume that the positive direction of the x-axis is the detection direction. In the first area (x>0), the main transmitting wireframe and the two auxiliary transmitting wireframes generate magnetic fields in the same direction, while in the second area (x<0), the two generate magnetic fields in opposite directions, that is, the composite magnetic field is superimposed in the same direction in the first area, and the magnetic induction intensity increases, and in the second area, it is reversely offset, and the magnetic induction intensity decreases. As a result, the primary magnetic field generated by the directional transmitting antenna can be significantly weakened on the side of the non-detection area, achieving the effect of directional emission of the excitation magnetic field in the detection area.

[0081] In an embodiment of the present application, the main transmitting antenna may include one main transmitting wire frame, two main transmitting wire frames or more main transmitting wire frames. For example, when two main transmitting wire frames are included, the normal directions of the two main transmitting wire frames coincide with the detection direction. The auxiliary transmitting antenna may include one auxiliary transmitting wire frame group, two auxiliary transmitting wire frame groups or more auxiliary transmitting wire frame groups. For example, when three auxiliary transmitting wire frame groups are included, the angle between the normal directions of any two auxiliary transmitting wire frame groups is greater than 0 degrees and less than or equal to 90 degrees. Exemplarily, the angle between the normals of the auxiliary transmitting wire frame group A and the auxiliary transmitting wire frame group B is 90 degrees, the angle between the normals of the auxiliary transmitting wire frame group A and the auxiliary transmitting wire frame group C is 45 degrees, and the angle between the normals of the auxiliary transmitting wire frame group B and the auxiliary transmitting wire frame group C is 45 degrees.

[0082] Optionally, at least one main transmitting wireframe is perpendicular to at least one auxiliary transmitting wireframe group, that is, each main transmitting wireframe is perpendicular to each auxiliary transmitting wireframe. It should be understood that the angle between any main transmitting wireframe and any auxiliary transmitting wireframe group can also be less than 90 degrees, and the embodiment of the present application does not limit the angle between the main transmitting wireframe and the auxiliary transmitting wireframe.

[0083] In each auxiliary transmission wireframe group, two auxiliary transmission wireframes are parallel and coaxial to each other and maintain a first preset distance. Optionally, the first preset distance is greater than 0 and less than or equal to the side length or diameter of any one of the two auxiliary transmission wireframes. It should be understood that the two auxiliary transmission wireframes in an auxiliary transmission wireframe group may not be parallel, and the embodiment of the present application does not limit the relationship between the two auxiliary transmission wireframes.

[0084] Furthermore, the sizes of the two auxiliary transmitting wire frames and the number of turns of the coils are the same, that is, the two auxiliary transmitting wire frames in an auxiliary transmitting wire frame group are the same, but in order to make them equivalent to two magnetic fields in opposite directions, the coils of the two auxiliary transmitting wire frames have the same winding direction and the current directions are opposite, or, the coils of the two auxiliary transmitting wire frames have opposite winding directions and the current directions are the same.

[0085] Optionally, the number of at least one auxiliary transmission wireframe group is an even number, that is, the auxiliary transmission antenna includes two auxiliary transmission wireframe groups, four auxiliary transmission wireframe groups, or other even multiples of auxiliary transmission wireframe groups. For example, when two auxiliary transmission wireframe groups are included, in the xyz spatial rectangular coordinate system, the magnetic fields generated by the two auxiliary transmission wireframe groups in the Y-axis and Z-axis directions are also magnetic fields in opposite directions, which can offset each other. Therefore, when the number of auxiliary transmission wireframe groups is an even number, the auxiliary transmission antenna can be prevented from affecting the magnetic fields in the Y-axis and Z-axis directions.

[0086] Optionally, the antenna structure also includes a receiving antenna, which includes at least one receiving wire frame, and Figure 4 The receiving antenna includes a receiving wire frame R x (Shown as a phantom in the figure).

[0087] Among them, at least one receiving wire frame is located on the zero magnetic flux plane of the second magnetic field or the third magnetic field, that is, the angle between the normal direction of at least one receiving wire frame and the normal direction of at least one main transmitting wire frame is 0 degrees or 90 degrees. At this time, the auxiliary transmitting wire frame group in the transmitting antenna will not affect the receiving antenna. For example, a receiving wire frame is located in the yOz plane at x=0 as shown in 5c, thereby eliminating the mutual inductance between the auxiliary transmitting wire frame group and the receiving antenna, reducing the influence of the primary magnetic field generated by the directional transmitting antenna on the early electromagnetic response signal, and avoiding the expansion of the detection blind area.

[0088] Optionally, the antenna structure further includes an insulating bracket, which is used to fix at least one main transmitting wire frame, at least one auxiliary transmitting wire frame group, and at least one receiving wire frame. The insulating bracket is also used to adjust the position of at least one main transmitting wire frame, at least one auxiliary transmitting wire frame group, and at least one receiving wire frame. That is, the insulating bracket supports the movement and rotation of each transmitting wire frame and receiving wire frame.

[0089] like Figure 6 As shown, the antenna structure provided in the embodiment of the present application can be applied to a transient electromagnetic detection device, which also includes components such as a host computer, a transmitter and a receiver. The transmitter includes a transmitting power supply, a control circuit, a driving circuit and a transmitting circuit, etc. The receiver includes an amplifying circuit, a filtering circuit, an analog / digital (Analog / Digital, A / D) conversion circuit and a storage circuit, etc. The circuit system in the transmitter can transmit a modulated current with the same phase to each transmitting wire frame in the transmitting antenna. The receiver is connected to at least one receiving wire frame in the receiving antenna to collect induced electromotive force data of at least one channel. The insulating bracket is used to fix the antenna system and supports the movement and rotation of each transmitting wire frame and receiving wire frame.

[0090] A conventional transmitting antenna (planar transmitting wireframe) and an antenna structure provided in an embodiment of the present application are used to perform transient electromagnetic detection in a tunnel advance drilling environment. Fig. 7A and Figure 7B The corresponding apparent resistivity inversion results are shown respectively (the darker the color, the lower the resistivity). By comparison, it can be seen that the transient electromagnetic directional detection device using the antenna structure provided in the embodiment of the present application can effectively identify the illusion caused by the full space effect and accurately locate the resistance anomaly.

[0091] The antenna structure provided in the embodiment of the present application is described in detail below with reference to several examples.

[0092] Example 1

[0093] like Figure 8A-8D As shown, the shapes of at least one main transmission wire frame and two auxiliary transmission wire frames include rectangle, trapezoid, circle, polygon and spiral. The main transmission antenna includes two main transmission wire frames T x1 and T x2 , main emission wireframe T x1 and T x2 They have a parallel and coaxial position relationship and maintain a certain spacing, and their sizes are different. The auxiliary transmitting antenna includes two auxiliary transmitting wire frame groups, that is, it includes four auxiliary transmitting wire frames, namely, T x3 、T x4 、T x5 and T x6 , auxiliary emission wireframe T x3 and T x4 With two main emission wireframe T x1 and T x2 Vertical, auxiliary emission wireframe T x5 and T x6 Not only with two main launch wireframes T x1 and T x2 Vertically, also with two auxiliary launch wireframe T x3 and T x4 The receiving antenna includes a receiving wire frame R x (shown as a phantom in the figure), receiving wireframe R x Set up two main emission wireframes T x1 and T x2 between.

[0094] Among them, Fig. 8A As shown, the two main emission wireframes T x1 and T x2 , four auxiliary emission wireframes T x3 、T x4 、T x5 and T x6 , and the receiving wireframe Rx are all rectangular or trapezoidal. Figure 8B As shown, the two main emission wireframes T x1 and T x2 and the receiving wireframe R x are all circular. Figure 8C As shown, the two main emission wireframes T x1 and T x2 and the receiving wireframe R x are all polygons. Fig.8D As shown, the two main emission wireframes T x1 and T x2 and the receiving wireframe R x All are spiral shaped.

[0095] It should be understood that the shapes of at least one main transmitting wireframe, two auxiliary transmitting wireframes in at least one auxiliary transmitting wireframe, and at least one receiving wireframe can also be other shapes, and there is no correlation between the shapes of the wireframes, which is not limited in this embodiment of the present application.

[0096] It should be understood that the parameters of the main transmitting antenna, the auxiliary transmitting antenna and the receiving antenna can be adjusted according to the application scenario, including size, number of turns, current intensity, current direction, winding direction, spatial position and connection method, etc. For example, the size of the antenna system can be scaled proportionally to adapt to tunnel scenarios and drilling scenarios, and the main transmitting wire frame T can be changed. x2 The current intensity in the primary magnetic field is such that the primary magnetic field is in opposite directions in the first region and the second region.

[0097] Example 2

[0098] like Figure 9A-9D As shown, the main transmitting antenna, auxiliary transmitting antenna and receiving antenna can be arranged into observation devices commonly used in transient electromagnetic detection, such as overlapping loops, center loops and dipole devices, wherein at least one receiving wire frame in the receiving antenna is located at the zero flux plane position of the auxiliary transmitting antenna, and only mutual inductance exists between the main transmitting antenna and the receiving antenna.

[0099] The main transmitting antenna includes a main transmitting wire frame T x1 The auxiliary transmitting antenna includes two auxiliary transmitting wire frame groups, namely, four auxiliary transmitting wire frames, namely, T x2 、T x3 、T x4 and T x5 , auxiliary emission wireframe T x2 and T x3 With the main launch wireframe T x1 Vertical, auxiliary emission wireframe T x4 and T x5 Not only with two launch wireframe T x1Vertically, also with two auxiliary launch wireframe T x2 and T x3 The receiving antenna includes one or more receiving wire frames R x (shown as a phantom in the figure), receiving wireframe R x and the main emission wireframe T x1 They have parallel and coaxial positional relationships, maintain a certain spacing, and have different sizes.

[0100] like Fig.9A The figure shows an overlapping loop device, where at least one main transmitting wire frame and at least one receiving wire frame have the same size and fit each other. Specifically, the main transmitting wire frame T x1 and receiving wireframe R x They have the same shape and size and overlap each other. When collecting electromagnetic signals in this way, they are most affected by the primary magnetic field and are suitable for medium and long-distance transient electromagnetic detection. Fig. 9B The central loop device is shown in FIG. 1 , wherein the size of at least one main transmitting wire frame is larger than that of at least one receiving wire frame, and at least one main transmitting wire frame is coplanar with at least one receiving wire frame and their center points coincide. Specifically, the main transmitting antenna T x1 Compared to the receiving wireframe R x With a larger size, the two are coplanar and their center points coincide. In this way, the electromagnetic signal is moderately affected by the primary magnetic field and the detection blind area is small. Fig. 9C The figure shows a dipole device, wherein at least one main transmitting wire frame is parallel to at least one receiving wire frame and is separated by a second preset distance. x1 and receiving wireframe R x The two are parallel and coaxial and maintain a certain distance between them. In this way, electromagnetic signals are collected with minimal influence from the primary magnetic field, which is suitable for short-range transient electromagnetic detection. Fig.9D As shown, since there are three mutually perpendicular zero flux planes in the magnetic field around the auxiliary transmitting antenna, three receiving wire frames can be arranged accordingly to collect three-component (x, y, z) induced electromotive force data.

[0101] Optionally, an insulating bracket is used to fix the antenna structure provided in the embodiment of the present application. The insulating bracket has the function of moving and rotating each transmitting wire frame and receiving wire frame, so that the structure of the directional transmitting antenna can be designed according to the construction environment. At the same time, the position of the receiving antenna can be adjusted according to the actual primary magnetic field, that is, the auxiliary transmitting antenna is independently controlled by the circuit system in the transmitter to generate a primary magnetic field, and each receiving wire frame is adjusted to the zero flux plane position therein.

[0102] It should be understood that in the embodiments of the present application, the transmitting antenna is used to summarize the main transmitting antenna and the auxiliary transmitting antenna, and the transmitting wire frame is used to summarize the main transmitting wire frame and the auxiliary transmitting wire frame. Other similar summary meanings can also be understood accordingly with reference to the above description, and the embodiments of the present application will not be repeated.

[0103] Summarizing the above embodiments, it can be seen that the beneficial effects brought by the antenna structure provided in the embodiments of the present application include but are not limited to the following three points:

[0104] (1) The main transmitting wireframe and the auxiliary transmitting wireframe group can superimpose the magnetic induction intensity in the same direction in the first area located in the detection direction, and reversely offset the magnetic induction intensity in the second area located in the non-detection direction. This can make the magnetic induction intensity in the detection area larger, so that the signal-to-noise ratio of the late electromagnetic signal is significantly improved, and the effective detection distance is increased. The metal body in the non-detection area is covered by the weakened primary magnetic field, and the influence of the full-space effect on transient electromagnetic detection is significantly weakened. The low-resistance anomaly illusion can be identified in the apparent resistivity inversion result.

[0105] (2) The receiving wireframes are all located at the zero flux plane of the auxiliary transmitting antenna. There is only mutual inductance between the main transmitting antenna and the receiving antenna. After eliminating the mutual inductance between the auxiliary transmitting antenna and the receiving antenna, the influence of the primary magnetic field generated by the directional transmitting antenna on the receiving antenna is significantly reduced, and the detection blind area is significantly reduced.

[0106] (3) When the number of auxiliary transmitting wireframe groups is an even number, the auxiliary transmitting antenna can be prevented from affecting the magnetic field in the Y-axis and Z-axis directions.

[0107] The antenna structure provided in the embodiment of the present application is introduced above. The transient electromagnetic detection device provided in the embodiment of the present application is introduced below with reference to the accompanying drawings.

[0108] like Fig.10 As shown, the transient electromagnetic detection device includes a transmitter, a host computer, a receiver, and the above-mentioned embodiment. Figure 4-9D The antenna structure shown.

[0109] Specifically, control software and data processing software are installed in the host computer, which is connected to the transmitter and receiver through the data communication module to realize command transmission and data transmission, and supports signal processing and inversion of the received induced electromotive force data to obtain the apparent resistivity information of the underground medium.

[0110] The circuit system of the transmitter is mainly composed of a control circuit, a drive circuit and a transmitting circuit. A transmitting power supply provides a stable voltage for the circuit system. After receiving the transmission command from the host, the control circuit and the drive circuit generate a pulse current or a bipolar square wave current with an adjustable duty cycle, and transmit the dual-channel modulated current to the main transmitting antenna and the auxiliary transmitting antenna respectively through the transmitting circuit.

[0111] The receiver includes an amplifying circuit, a filtering circuit, an A / D conversion circuit, a storage circuit, etc. In the receiver, the electromagnetic signal of at least one channel can be processed by pre-time base correction, amplification, noise removal, A / D conversion, etc.

[0112] Optionally, the circuit system can also support multi-channel transmission, that is, according to the instructions of the host computer, the control circuit and the drive circuit generate multi-channel current signals with the same phase and transmit them independently to multiple designated transmission wire frames through the transmission circuit. That is, the transmitter includes multiple interfaces, specifically in the form of a transmitter expansion dock, and the transmitter is connected to the transmitting antenna in the antenna structure through multiple interfaces. Similarly, the receiver can also include multiple interfaces, and the receiver is connected to the receiving antenna in the antenna structure through multiple interfaces.

[0113] exist Fig.10 In the transient electromagnetic detection device shown in the figure, the main transmitting antenna includes a main transmitting wire frame T x1 The auxiliary transmitting antenna is composed of two auxiliary transmitting wireframe groups with a normal direction angle of 90°, namely, the auxiliary transmitting wireframe T x2 、T x3 、T x4 and T x5 The receiving antenna includes a receiving wire frame R x When the transmitting current is turned off, a transient primary magnetic field is generated around the transmitting antenna. Under the action of electromagnetic induction, induced eddy currents and secondary magnetic fields are generated in the underground medium. The attenuation process of the secondary magnetic field is observed through the receiving antenna, and the electromagnetic response signal carrying the resistivity information of the underground medium is collected.

[0114] For example, the positive direction of the x-axis is assumed to be the detection direction. Fig.11 The distribution of the primary magnetic field generated by the antenna structure provided by the embodiment of the present application is shown. The combination of the main transmitting antenna and the auxiliary transmitting antenna can increase the magnetic induction intensity in the first area (x>0), while the primary magnetic field in the second area (x<0) is significantly weakened. In addition, in the non-detection directions along the y-axis and the z-axis, the corresponding magnetic field components generated by the main transmitting antenna and the auxiliary transmitting antenna are both small.

[0115] In this embodiment, when the antenna structure is applied to a transient electromagnetic detection device, each transmitting wire frame in the main transmitting antenna and the auxiliary transmitting antenna is independently connected to the transmitter and loaded with a modulated current with the same phase, and the circuit system in the transmitter adopts a corresponding multi-channel design. In the auxiliary transmitting antenna, the two auxiliary transmitting wire frames constituting the auxiliary transmitting wire frame group need to generate magnetic fields in opposite directions. Currents in opposite directions can be passed through the two auxiliary transmitting wire frames with the same winding direction, or currents in the same direction can be passed through the two auxiliary transmitting wire frames with opposite winding directions. In addition, the respective transmitting wire frames in the main transmitting antenna and the auxiliary transmitting antenna can be connected in series, and the current signal can be transmitted to the two synchronously through the transmitter. This series-type directional transmitting antenna can also be understood as being wound by two wires, and the two parts of the structure are respectively equivalent to the main transmitting antenna and the auxiliary transmitting antenna.

[0116] In the several embodiments provided in the present application, it should be understood that the disclosed structure can be implemented in other ways. For example, the embodiments described above are merely illustrative, and for example, the division of the structure can be divided in other ways in actual implementation, such as multiple units or components can be combined or integrated into another structure, or some features can be ignored. Some or all of the structures can be selected according to actual needs to achieve the purpose of the present embodiment.

[0117] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An antenna structure, characterized in that: The method comprises at least one main transmission wireframe and at least one auxiliary transmission wireframe group, wherein each auxiliary transmission wireframe group in the at least one auxiliary transmission wireframe group comprises two auxiliary transmission wireframes; The at least one main transmitting wire frame is used to generate a first magnetic field in a first area and a second area, and two sides of the at least one main transmitting wire frame are respectively the first area and the second area; The at least one auxiliary transmitting wire frame group is used to generate a second magnetic field in the first area with the same direction as the first magnetic field, and to generate a third magnetic field in the second area with the opposite direction to the first magnetic field.

2. The antenna structure according to claim 1, characterized in that: It also includes at least one receiving wire frame, and the at least one receiving wire frame is located on a zero magnetic flux plane of the second magnetic field or the third magnetic field.

3. The antenna structure according to claim 2, characterized in that: The angle between the normal direction of the at least one receiving wireframe and the normal direction of the at least one main transmitting wireframe is 0 degrees or 90 degrees.

4. The antenna structure according to any one of claims 1 to 3, characterized in that: The number of the at least one auxiliary transmission wireframe group is an even number.

5. The antenna structure according to any one of claims 1 to 4, characterized in that: The at least one main transmitting wire frame is perpendicular to the at least one auxiliary transmitting wire frame group.

6. The antenna structure according to any one of claims 1 to 5, characterized in that: In the at least one auxiliary emission wireframe group, an angle between normal directions of any two auxiliary emission wireframe groups is greater than 0 degree and less than or equal to 90 degrees.

7. The antenna structure according to any one of claims 1 to 6, characterized in that: The two auxiliary emission wire frames are parallel to each other and maintain a first preset distance between them.

8. The antenna structure according to claim 7, characterized in that: The first preset distance is greater than 0 and less than or equal to the side length or diameter of any one of the two auxiliary transmission wire frames.

9. The antenna structure according to any one of claims 1 to 8, characterized in that: The sizes of the two auxiliary transmitting wire frames and the number of turns of the coils are the same.

10. The antenna structure according to any one of claims 1 to 9, characterized in that: The coils of the two auxiliary transmitting wire frames are wound in the same direction and the currents are in opposite directions; Alternatively, the coils of the two auxiliary transmitting wire frames are wound in opposite directions and have the same current direction.

11. The antenna structure according to any one of claims 1 to 10, characterized in that: It also includes an insulating bracket, which is used to fix the at least one main transmitting wire frame and the at least one auxiliary transmitting wire frame group.

12. The antenna structure according to claim 11, characterized in that: The insulating support is also used to adjust the positions of the at least one main transmitting wire frame and the at least one auxiliary transmitting wire frame group.

13. The antenna structure according to any one of claims 1 to 12, characterized in that: The shapes of the at least one main transmitting wire frame and the two auxiliary transmitting wire frames include rectangular, trapezoidal, circular, polygonal and spiral.

14. The antenna structure according to any one of claims 2 to 13, characterized in that: The at least one main transmitting wire frame and the at least one receiving wire frame have the same size and fit each other.

15. The antenna structure according to any one of claims 2 to 13, characterized in that: The at least one main transmitting wireframe has a size larger than the at least one receiving wireframe, and the at least one main transmitting wireframe is coplanar with the at least one receiving wireframe and their center points coincide with each other.

16. The antenna structure according to any one of claims 2 to 13, characterized in that: The at least one main transmitting wire frame is parallel to the at least one receiving wire frame and is spaced apart by a second preset distance.

17. A transient electromagnetic detection device, characterized in that: It comprises a transmitter, a host computer, a receiver and an antenna structure as claimed in any one of claims 1 to 16.

18. The device according to claim 17, characterized in that The transmitter comprises a plurality of interfaces, and the transmitter is connected to the antenna structure via the plurality of interfaces.

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