Azimuthal electromagnetic wave probe and method for determining angle of equivalent magnetic dipole moment thereof

Abstract

The application relates to an azimuth electromagnetic wave probe and a method for determining the angle of the equivalent magnetic dipole moment of the probe, wherein the azimuth electromagnetic wave probe comprises a framework, a hollow core rod sleeved outside the framework and provided with a plurality of notched grooves extending from the outer surface of the core rod at a preset angle and arranged in mirror symmetry with a specific longitudinal section as a symmetrical plane, a coil antenna arranged around the core rod, and a magnetic piece arranged in the notched groove, and a radome sleeved outside the coil antenna and provided with a through opening corresponding to the magnetic piece. The azimuth electromagnetic wave probe can effectively shorten the size of the azimuth electromagnetic wave probe and enhance the directivity of the transmitting coil compared with the prior art.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil logging, and particularly relates to a directional electromagnetic wave probe and a method for determining the angle of the equivalent magnetic dipole moment thereof. BACKGROUND

[0002] Most of the existing commercial directional electromagnetic wave resistivity logging instruments for while-drilling adopt tilted coil antennas to measure the directional information of the formation. The greater the tilt angle of the directional coil, the stronger the directivity of the antenna radiation. Due to the size limitation of the drill collar, the industry generally adopts a 45-degree tilted coil directly wound on the drill collar, and the angle of the equivalent magnetic dipole moment of the coil is also about 45 degrees. If the relative angle between the normal direction of the coil and the axial direction of the instrument is to be increased to enhance the directivity, the tilt angle of the coil winding must be increased, resulting in an increase in the size of the coil. Especially in the near-bit measuring instrument, the length of the instrument body is limited to about 1 meter, and the size of the coil is limited by the size of the whole machine. The tilt angle of the coil winding is small, resulting in a small relative angle between the direction of the equivalent magnetic dipole moment of the coil and the axial direction of the instrument, and it is difficult to obtain good directional performance. SUMMARY

[0003] To solve the problem that the directivity of the tilted coil in the prior art is positively correlated with the physical size of the coil, and that increasing the directivity increases the size of the coil, it is necessary to provide a directional electromagnetic wave probe and a method for determining the angle of the equivalent magnetic dipole moment thereof.

[0004] The directional electromagnetic wave probe of the present application can effectively shorten the size of the directional electromagnetic wave probe compared with the prior art, and can enhance the directivity of the transmitting coil by only increasing the angle of the opening of the antenna cover without increasing the size of the coil.

[0005] To achieve the above-mentioned purpose, the present application provides a directional electromagnetic wave probe and a method for determining the angle of the equivalent magnetic dipole moment thereof. The angle of the equivalent magnetic dipole moment of the directional electromagnetic wave probe refers to the relative included angle between the direction of the equivalent magnetic dipole moment of the directional electromagnetic wave probe and the axial direction of the directional electromagnetic wave probe.

[0006] According to a first aspect of the present application, there is provided a directional electromagnetic wave probe, comprising:

[0007] a core rod having a plurality of grooves extending from the outer surface thereof at a non-zero preset angle to be mirror-symmetrically arranged with a specific one longitudinal section as a plane of symmetry and made of a non-magnetic conductive material;

[0008] a coil antenna arranged around the core rod;

[0009] a magnetic member arranged in the groove; and

[0010] An antenna cover is arranged outside the coil antenna, and has a through opening corresponding to the magnetic member and is made of a non-magnetic conductive material. The antenna cover and the core rod are in good conductive connection.

[0011] Further, the core rod is arranged on the framework.

[0012] Further, the coil antenna is a ring coil antenna or a square coil antenna for applying an alternating current of a certain frequency.

[0013] Further, the core rod and the antenna cover are made of a non-magnetic material with an electrical conductivity higher than 1000 S / m.

[0014] Further, a plurality of the magnetic members are arranged along the circumference of the core rod.

[0015] Further, the core rod has an outer surface with a groove, the groove is filled with the magnetic member, and the groove is distributed in accordance with the through opening of the antenna cover.

[0016] Further, the openings on the antenna cover are arranged in mirror symmetry with a certain longitudinal section as a symmetric plane according to a preset angle, that is, the opening angle of the antenna cover on one side of the longitudinal section is the preset angle, and the opening angle of the antenna cover on the other side of the longitudinal section is the negative value of the preset angle. The preset angle is the relative angle between the long side direction of the groove on the core rod and the axial direction of the core rod. The preset angle is a non-zero value.

[0017] The coil antenna is arranged around the core rod, and the normal line of the coil antenna and a certain longitudinal section of the core rod serving as a groove symmetric plane are coplanar.

[0018] Optionally, the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe can be changed by adjusting the groove angle on the core rod around the azimuthal electromagnetic wave probe and the opening angle on the corresponding antenna cover. The groove angle on the core rod refers to the relative angle between the long side direction of the groove and the axial direction of the core rod, and the opening angle on the antenna cover refers to the relative angle between the long side direction of the opening and the axial direction of the antenna cover. The greater the relative angle between the groove and the opening of the antenna cover and the axial direction of the core rod, the better the azimuthal performance of the probe. Generally, the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe is greater than the relative angle between the groove and the opening of the antenna cover and the axial direction of the core rod.

[0019] According to a second aspect of the present application, a method for determining the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe is provided, comprising:

[0020] S1: horizontally placing the azimuthal electromagnetic wave probe on a non-conductive rotating support on a metal plate spaced apart from the azimuthal electromagnetic wave probe by a first preset distance and rotating the azimuthal electromagnetic wave probe along its axial direction by a preset angle;

[0021] S2: placing a coil antenna at a second preset distance apart from the axial direction of the azimuthal electromagnetic wave probe, receiving an induced signal of a certain rotation angle of the azimuthal electromagnetic wave probe, and recording the rotation angle and the corresponding electromotive force;

[0022] S3: adjusting the first preset distance between the azimuthal electromagnetic wave probe and the metal plate, and repeating steps S1 and S2 a preset number of times;

[0023] S4: using a magnetic dipole source electromagnetic response numerical simulation program to calculate the ideal value of the signal at the receiving coil antenna when the metal plate is spaced apart by different first preset distances, changing the magnetic dipole moment angle of the transmitting magnetic dipole, until the mean square error between the ideal value and the measured value is minimized, and the magnetic dipole moment angle of the transmitting magnetic dipole corresponding to the minimum mean square error is the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe.

[0024] Preferably, the equivalent magnetic dipole moment direction of the placed receiving coil antenna is consistent with the axial direction of the azimuthal electromagnetic wave probe.

[0025] Further, the preset angle of rotating the azimuthal electromagnetic wave probe along its axial direction is 360 degrees.

[0026] Further, the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe is changed by adjusting the angle of the notch on the core rod surrounding the coil antenna and the angle of the opening on the corresponding antenna cover. The angle of the notch on the core rod of the azimuthal electromagnetic wave probe and the angle of the opening on the corresponding antenna cover directly determine the directivity of the electromagnetic field generated by the azimuthal electromagnetic wave probe.

[0027] The equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe refers to the relative included angle between the direction of the equivalent magnetic dipole moment of the azimuthal electromagnetic wave probe and the axial direction of the azimuthal electromagnetic wave probe.

[0028] From the above technical solution, the azimuthal electromagnetic wave probe provided by the application comprises: a framework; a hollow core rod, which is sleeved outside the framework and has a plurality of notches extending from its outer surface along a preset angle and arranged in mirror image symmetry with its longitudinal section as the symmetry plane; a coil antenna, which is arranged around the core rod; and a magnetic member, which is arranged in the notch. And an antenna cover, which is sleeved outside the coil antenna and has a through opening corresponding to the magnetic member.

[0029] The azimuth electromagnetic wave probe has the advantages of effectively shortening the size of the azimuth electromagnetic wave probe and enhancing the directivity of the transmitting antenna. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A sectional view of the azimuth electromagnetic wave probe of the embodiment of the present application;

[0031] Figure 2 A front view of the azimuth electromagnetic wave probe of the embodiment of the present application;

[0032] Figure 3 A perspective view of the radome of the embodiment of the present application;

[0033] Figure 4 A perspective view of the radome of another embodiment of the present application; DETAILED DESCRIPTION

[0034] In order to better understand the purpose, structure and function of the present application, the azimuth electromagnetic wave probe and the method for determining the equivalent magnetic dipole moment angle of the present application are described in further detail below in combination with the drawings.

[0035] As Figure 1 , Figure 2As shown, it shows an azimuthal electromagnetic wave probe of an embodiment of the present application. Specifically, the azimuthal electromagnetic wave probe of the embodiment of the present application comprises a framework 101, a core rod 102, a magnetic member 103, a coil antenna 104, and a radome 105. Wherein the core rod 102 has a plurality of groove bodies 106 (also can be called as engraved grooves) extending from its outer surface along a preset angle and arranged in mirror symmetry with a specific longitudinal section thereof as a symmetry plane, and is made of a non-magnetic conductive material, and the coil antenna 104 is arranged around the core rod 102 to apply an alternating current of a certain frequency. The normal direction of the coil antenna 104 and the axial direction of the core rod 102 are the same, or the normal direction of the coil antenna 104 and the axial direction of the core rod 102 are at a certain angle and coplanar with the specific longitudinal section of the core rod 102 as the symmetry plane of the engraved groove. The magnetic member 103 is arranged in the groove body 106. The radome 105 is sleeved outside the coil antenna 103 and is provided with a series of through openings 107 corresponding to the magnetic member 103 and the groove body 106. The included angle between the long edge direction of the groove body 106 and the axial direction of the core rod 102 and the included angle between the long edge direction of the radome opening 107 and the axial direction of the core rod 102 are both a non-zero preset included angle 108. The plurality of groove bodies 106 are arranged in mirror symmetry with a specific longitudinal section of the core rod 102 as a symmetry plane. The included angle between the long edge direction of the groove body 106 on one side of the specific longitudinal section of the core rod 102 and the axial direction of the core rod 102 is a non-zero preset included angle 108, and the included angle between the long edge direction of the groove body 106 on the other side of the specific longitudinal section of the core rod 102 and the axial direction of the core rod 102 is a non-zero preset included angle 109. The absolute values of the preset included angle 108 and the preset included angle 109 are equal. The groove body 106 and the through opening 107 are distributed in mirror symmetry with a specific longitudinal section of the core rod 102 as a symmetry plane, and there is at least one groove body 106 and a through opening 107 corresponding to the groove body 106 on each side of the symmetry plane.

[0036] The azimuthal electromagnetic wave probe of the embodiment of the present application with the above characteristics can effectively shorten the size of the azimuthal electromagnetic wave probe and enhance the directivity characteristics of the transmitting antenna compared with the prior art.

[0037] Specifically, the hollow core rod 102 is sleeved outside the framework 101 and has groove bodies 106 extending from its outer surface along a preset angle and arranged in mirror symmetry with a specific longitudinal section thereof as a symmetry plane, the coil antenna 104 is arranged around the core rod 102, and the magnetic member 103 is arranged in the groove body 106. The magnetic member 103 can preferably be a magnetic material with a relative permeability greater than 50 and an electrical resistivity greater than 1000 ohm meters.

[0038] The core rod 102 and the radome 105 are made of a non-magnetic material with an electrical conductivity higher than 1000 S / m.

[0039] The antenna cover 105 is sleeved outside the coil antenna 103, and the coil antenna 103 is covered to protect the coil antenna. The antenna cover 105 is made of a non-magnetic material with an electrical conductivity higher than 1000 S / m, and a series of through openings 107 corresponding to the groove bodies 106 on the core rod 102 are formed on the outer side of the antenna cover 105. The antenna cover 105 and the core rod 102 are in good conductive connection. The antenna cover 105 has a certain thickness to play an electromagnetic shielding role, so that the electromagnetic energy emitted by the coil 103 is only radiated to the outside space of the probe through the through openings 107.

[0040] The gap space in the azimuthal electromagnetic wave probe is filled with an insulating non-magnetic material. The filling materials in the gaps of the groove bodies 106 and the openings 107 on the antenna cover are non-conductive non-magnetic materials such as epoxy resin or glass steel.

[0041] In a specific embodiment, the core rod of the embodiment of the present application is made of a non-magnetic stainless steel material, and of course can be other conductive non-magnetic materials, which are not specifically limited here. The magnetic member is made of a ferrite material, and the relative magnetic permeability is greater than 100, and the resistivity is greater than 10 6 ohm meter. Of course, it can also be other non-conductive magnetic materials, which are not specifically limited here. The coil antenna of the embodiment of the present application is a single-turn or multi-turn loop coil antenna or a square coil antenna, and of course can be other forms of coil antennas, which are not specifically limited here.

[0042] As shown in Figure 3 , specifically, the cover body 201 of the antenna cover 105 has square through openings 202. The long side direction of the through openings 202 is at an angle of 45° with the axial direction of the antenna cover 105, and is mirror-symmetrically arranged with the specific longitudinal section 203 of the antenna cover 105 as the symmetry plane, and the through openings 202 are filled with an insulating non-magnetic material; wherein the electromagnetic energy of the coil antenna 104 is radiated through the through openings 202. The groove bodies 106 on the core rod 102 correspond to the through openings 102 and have the same trend. The antenna cover 105 and the core rod 102 are in good conductive connection and have a certain thickness, which ensures that the electromagnetic energy radiated by the coil antenna is only transmitted out of the azimuthal electromagnetic wave probe through the through openings 202 on the antenna cover 105.

[0043] Alternatively, as shown in Figure 4 , the cover body 401 of the antenna cover 105 has square through openings 402 (also called grooves or gaps). The long side direction of the openings 402 is at an angle of 60° with the axial direction of the antenna cover 105, and is mirror-symmetrically arranged with the specific longitudinal section of the antenna cover 5 as the symmetry plane, and is filled with an insulating non-magnetic material; wherein the cover body 401 of the antenna cover 105 has a certain thickness to play an electromagnetic shielding role, so that the electromagnetic energy emitted by the coil antenna 104 is only radiated out through the through openings 402.

[0044] In a specific embodiment, the cover 401 has a plurality of square through openings 402, and the plurality of square openings 402 are arranged along the circumference of the cover 401. The plurality of openings 402 are arranged in mirror symmetry along the outer surface of the cover 401 with a specific one of the longitudinal sections as the plane of symmetry, that is, the opening angle of the antenna cover on one side of the longitudinal section is a preset angle, and the opening angle of the antenna cover on the other side of the longitudinal section is the negative value of the preset angle. The preset angle is the included angle between the long side of the groove on the mandrel and the axial direction of the mandrel.

[0045] In addition, the mandrel 102 of the present application has grooves on the outer surface to accommodate the magnetic members 103, and the grooves are filled with magnetic material (the magnetic material constitutes the magnetic members). The distribution of the grooves is consistent with the through openings 107 of the antenna cover, so that the plurality of magnetic members are arranged along the circumference of the mandrel 102. Specifically, the mandrel 102 with grooves has a groove distribution and a direction consistent with the openings 107 of the antenna cover.

[0046] Optionally, the angle of the groove on the mandrel around the azimuthal electromagnetic wave probe and the angle of the opening on the corresponding antenna cover can be adjusted to change the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe. The larger the angle of the groove and the opening of the antenna cover, the better the azimuthal performance of the probe. The angle of the groove on the mandrel of the azimuthal electromagnetic wave probe and the angle of the opening on the corresponding antenna cover can directly determine the directivity of the electromagnetic field generated by the electromagnetic wave probe.

[0047] The azimuthal electromagnetic wave probe of the present application comprises, from the inside out, a mandrel with grooves, a magnetic material, a coil, and an antenna cover. The probe can be equivalent to a directional magnetic dipole. The equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe is determined by a combination of physical experiments and numerical simulation methods. The equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe refers to the included angle between the direction of the equivalent magnetic dipole moment of the azimuthal electromagnetic wave probe and the axial direction of the azimuthal electromagnetic wave probe. Compared with the prior art, the present application can effectively shorten the size of the azimuthal electromagnetic wave probe and enhance the directivity characteristics of the transmitting antenna.

[0048] According to the second aspect of the present application, the present application also provides a method for determining the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe as described above, which comprises the following steps:

[0049] S1: horizontally placing the azimuthal electromagnetic wave probe on a non-conductive rotating support on a metal plate spaced apart from the azimuthal electromagnetic wave probe by a first preset distance and rotating the azimuthal electromagnetic wave probe along its axial direction by a preset angle;

[0050] S2: placing a coil antenna at a second preset distance in the axial direction of the azimuthal electromagnetic wave probe, receiving the induced signal of a certain rotation angle of the azimuthal electromagnetic wave probe, and recording the rotation angle and the corresponding electromotive force.

[0051] S3: adjusting a first preset distance between the azimuthal electromagnetic wave probe and the metal plate, and repeating step S1 and step S2 a preset number of times;

[0052] S4: calculating ideal values of signals at the receiving coil antenna at different heights by using a magnetic dipole source electromagnetic response numerical simulation program, changing a magnetic dipole moment angle of the transmitting magnetic dipole, and until a mean square error between the ideal values and the measured values is minimum, and the magnetic dipole moment angle of the transmitting magnetic dipole corresponding to the minimum mean square error is an equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe.

[0053] Further, the preset angle is 360 degrees.

[0054] Further, a direction of the equivalent magnetic dipole moment of the coil antenna for receiving signals forms a 0-degree angle with an instrument axial direction.

[0055] Specifically, the method for determining the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe includes:

[0056] S11: placing a high-conductivity metal plate with a certain thickness on the ground, placing the azimuthal electromagnetic wave probe on a non-conductive rotating support on the high-conductivity metal plane at a fixed height, placing the high-conductivity metal plane on the ground, and rotating the azimuthal electromagnetic wave probe along the axial direction by 360 degrees.

[0057] S12: placing a coil antenna at an interval of a certain distance along the axial direction of the azimuthal electromagnetic wave probe, receiving an induced signal corresponding to a certain rotation angle of the azimuthal electromagnetic wave probe, and recording the rotation angle, the real part and the imaginary part of the electromotive force.

[0058] S13: changing the distance between the azimuthal electromagnetic wave probe and the high-conductivity metal plane, and repeating S1-S2.

[0059] S14: calculating ideal values of signals at the receiving antenna at different heights by using a magnetic dipole source electromagnetic response numerical simulation program, constantly changing a magnetic dipole moment angle of the transmitting magnetic dipole, so that a mean square error between the calculated values and the measured values is minimum. The magnetic dipole moment angle of the transmitting magnetic dipole at this time is the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe.

[0060] In a specific embodiment, the method for determining the equivalent magnetic dipole moment of the azimuthal electromagnetic wave probe includes the following steps:

[0061] obtaining a physical experiment signal of the azimuthal electromagnetic wave probe;

[0062] The measurement step of the physical experiment signal includes:

[0063] A high-conductivity metal plate with a certain thickness is placed on the ground, an azimuth electromagnetic wave probe is horizontally placed on a non-conductive rotating support of the high-conductivity metal plane at a fixed height, and the high-conductivity metal plane is placed on the ground. The azimuth electromagnetic wave probe is rotated by 360 degrees along the axial direction.

[0064] A coil antenna is placed at a certain distance from the azimuth electromagnetic wave probe in the axial direction to receive an induced signal corresponding to a certain rotation angle of the azimuth electromagnetic wave probe, and the rotation angle, the real part and the imaginary part of the electromotive force are recorded.

[0065] The distance between the azimuth electromagnetic wave probe and the high-conductivity metal plane is changed, and the above steps are repeated.

[0066] The numerical simulation signal of the azimuth electromagnetic wave probe is obtained and compared with the physical experiment signal.

[0067] The numerical simulation signal includes: using a magnetic dipole source electromagnetic response numerical calculation program to simulate the ideal value of the electromotive force or the redefined signal at the receiving antenna at different heights, changing the magnetic dipole moment angle of the transmitting magnetic dipole to minimize the mean square error between the calculated value and the measured value. At this time, the magnetic dipole moment angle of the transmitting magnetic dipole is the equivalent magnetic dipole moment angle of the azimuth electromagnetic wave probe.

[0068] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present application should be understood as the usual meanings understood by the skilled person in the field to which the present application belongs.

[0069] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "axial direction", "radial direction", "circumferential direction" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0070] In the present application, unless otherwise specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0071] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An azimuthal electromagnetic wave probe, characterized by, The azimuthal electromagnetic wave probe comprises a core rod, a coil antenna, a magnetic element and a radome. The core rod is made of non-magnetic conductive material and has a plurality of grooves extending from its outer surface at a non-zero preset angle and arranged in mirror symmetry with a specific longitudinal section as the symmetry plane. The coil antenna is arranged around the core rod. The magnetic element is arranged in the groove. The radome is arranged outside the coil antenna, has a through opening corresponding to the magnetic element, is made of non-magnetic conductive material, and is electrically connected with the core rod. The distribution of the grooves is consistent with the through opening on the radome.

2. The azimuthal electromagnetic wave probe of claim 1, wherein, The core rod is arranged on a skeleton.

3. The azimuthal electromagnetic wave probe of claim 1, wherein, The coil antenna is a ring coil antenna or a square coil antenna.

4. The azimuthal electromagnetic wave probe of claim 1, wherein, A plurality of magnetic elements are arranged along the circumference of the core rod.

5. The azimuthal electromagnetic wave probe of claim 1, wherein, The through opening on the radome is arranged in mirror symmetry with a specific longitudinal section as the symmetry plane at a non-zero preset angle.

6. The orientation electromagnetic wave probe according to claim 1, characterized by The gap part of the azimuthal electromagnetic wave probe is filled with insulating non-magnetic material.

7. A method of determining the angle of the equivalent magnetic dipole moment of an azimuthal electromagnetic wave probe according to any one of claims 1 to 6, characterized in that, The azimuthal electromagnetic wave probe comprises a core rod, a coil antenna, a magnetic element and a radome. S1: horizontally place the azimuthal electromagnetic wave probe on a non-conductive rotating support of a metal plate spaced apart from the azimuthal electromagnetic wave probe by a first preset distance, and rotate the azimuthal electromagnetic wave probe along its axial direction by a preset angle. S2: place a coil antenna at a second preset distance apart from the azimuthal electromagnetic wave probe in the axial direction, receive the induced signal of a certain rotation angle of the azimuthal electromagnetic wave probe, and record the rotation angle and the corresponding electromotive force. S3: adjust the first preset distance between the azimuthal electromagnetic wave probe and the metal plate, and repeat steps S1 and S2 a preset number of times. S4: use a magnetic dipole source electromagnetic response numerical simulation program to calculate the ideal value of the signal received by the coil antenna at different first preset distances, change the magnetic dipole moment angle of the transmitting magnetic dipole, and until the mean square error between the ideal value and the measured value is minimized, the magnetic dipole moment angle of the transmitting magnetic dipole corresponding to the minimum mean square error is the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe.

8. The method of claim 7, wherein, The equivalent magnetic dipole moment direction of the placed receiving coil antenna is consistent with the axial direction of the azimuthal electromagnetic wave probe.

9. The method of claim 7, wherein, By adjusting the groove angle on the core rod around the azimuthal electromagnetic wave probe and the opening angle on the corresponding radome, the equivalent magnetic dipole moment angle of the azimuthal electromagnetic wave probe can be changed.

Images