Magneto-impedance gradient current sensor and current measuring and positioning method thereof

Abstract

According to the magneto-impedance gradient current sensor and the current measuring and positioning method thereof, four high-sensitivity magneto-impedance sensors with the same characteristics are arranged around a wire through which current to be measured flows, two of the four high-sensitivity magneto-impedance sensors are arranged on the x axis, the other two of the four high-sensitivity magneto-impedance sensors are arranged on the y axis, and the induction direction of the high-sensitivity magneto-impedance sensors is perpendicular to the wire; when current flows through the wire, a magnetic field perpendicular to the wire is generated around the wire, and the four high-sensitivity magneto-impedance sensors respectively measure the magnetic field intensity values of the positions where the four high-sensitivity magneto-impedance sensors are located, so that the current value flowing through the wire and the position of the current are obtained. According to the invention, the current position can be determined while the current value is measured with high precision. The sensitivity and the resolution in the current test can be remarkably improved, and higher-precision detection of the current value and the position of the current value can be realized. And meanwhile, the position and the size of the detected current can be accurately calculated under the condition that the current lead is not contacted and damaged, so that the application scene is wider.

Description

Technical Field

[0001] The invention relates to the technical field of measuring current with a magneto-impedance current sensor, and in particular to a method for measuring current and its position based on a magneto-impedance gradient current sensor and a gradient current sensor used therein. Background Art

[0002] Gradient current sensors have important application value in fields such as precision electromagnetic measurement. With the growing demand for high-sensitivity, high-resolution and miniaturized sensors in modern technology, traditional current sensors, such as current sensors based on the Hall effect and optical current sensors, have gradually shown certain limitations. For example, the sensitivity of Hall effect sensors is limited at low currents, and although optical current sensors have high precision, they are usually expensive and difficult to miniaturize. Therefore, it is particularly important to develop a gradient current sensor with high sensitivity, fast response, compact structure and suitable for weak current detection. The magneto-impedance (GMI) effect is a physical phenomenon in which the impedance of a material changes significantly due to changes in the magnetic field. It exhibits the advantages of high sensitivity and wide-band response in weak magnetic field detection. Highly sensitive magneto-impedance sensors based on the magneto-impedance effect have become a research hotspot in the field of weak magnetic field and low current detection due to their miniaturization, high sensitivity and low power consumption. This type of sensor can indirectly achieve high-precision detection of the current size by measuring the weak magnetic field generated by the current, and is particularly suitable for gradient current distribution measurement in complex environments. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for measuring current and its position using a magneto-impedance gradient current sensor in view of the shortcomings of the prior art. The present invention is based on a gradient current sensor of a high-sensitivity magneto-impedance sensor, which can significantly improve the sensitivity and resolution in current testing and can achieve higher-precision detection of current value and its position.

[0004] Another object of the present invention is to provide a magneto-impedance gradient current sensor used in the method for measuring current and its position using the magneto-impedance gradient current sensor.

[0005] In order to solve the technical problem of the present invention, the following technical solution is adopted: A method for measuring current and its position using a magnetic impedance gradient current sensor, wherein four high-sensitivity magnetic impedance sensors with the same characteristics are placed around a conductor through which the current to be measured flows, wherein two are placed on the x-axis and two are placed on the y-axis, and the sensing direction of the high-sensitivity magnetic impedance sensors is perpendicular to the conductor; when the current flows through the conductor, a magnetic field perpendicular to the conductor is generated around the conductor due to the Ampere loop theorem, and the magnetic field strength values ​​B1, B2, B3, and B4 at the positions where the four high-sensitivity magnetic impedance sensors are located are obtained by the Ampere loop theorem, and at the same time, the four high-sensitivity magnetic impedance sensors respectively measure the magnetic field strength values ​​B1, B2, B3, and B4 at the positions where they are located.a , B b , B c , B d , B a =B1, B b =B2, B c =B3, B d =B4, the four equations give the current value I flowing through the wire and the position of the current (x0, y0).

[0006] Taking (0, 0) as the origin, a high-sensitivity magneto-impedance sensor is placed at four points: (-R, 0), (R, 0), (0, -R), and (0, R).

[0007] The output voltage value range of the high-sensitivity magnetoimpedance sensor is between -12V and +12V. For every 5.56uT change in the ambient magnetic field of the high-sensitivity magnetoimpedance sensor, its output value changes by 1V. The magnetic voltage conversion coefficient of the high-sensitivity magnetoimpedance sensor is 180000V / T, denoted as S.

[0008] For a fixed magnetic field strength value, the high-sensitivity magneto-impedance sensor senses the magnetic field generated by the conductor and outputs a DC voltage value, which is recorded as V1, V2, V3, and V4. The magnetic voltage conversion coefficient of the four high-sensitivity magneto-impedance sensors is S, and the unit is V / T. The DC voltage value output by the high-sensitivity magneto-impedance sensor is divided by its magnetic voltage conversion coefficient to obtain the magnetic field strength value B after the high-sensitivity magneto-impedance sensor. a , B b , B c , B d , then: B a = V1 / S, B b = V2 / S, B c = V3 / S, B d = V4 / S.

[0009] According to Ampere's circuit theorem: , where B represents the magnetic field strength, the unit is Tesla, T; m 0 is the vacuum permeability, which is m 0=4π*10 -7 H / m, I0 represents the current intensity, the unit is ampere, A; r is the distance between the high-sensitivity magnetic impedance sensor and the straight line where the current is located, the unit is meter, m; with (0, 0) as the origin, high-sensitivity magnetic impedance sensors are placed at four points (-R, 0), (R, 0), (0, -R), and (0, R), and R is the distance between each high-sensitivity magnetic impedance sensor and the origin; the flow position of the current to be measured is (x0, y0), and the current value to be measured is I. According to the above formula, the magnetic field intensity values ​​generated by the current to be measured at the four positions are: , , , , solving the corresponding equations yields: , , substitute m 0, R, π, V1, V2, V3, V4, and S, then determine the current value I and position (x0, y0) of the conductor to be tested.

[0010] The magnetic voltage conversion coefficient of the high-sensitivity magneto-impedance sensor is determined as follows: a magnetic shielding tank is taken, in which there is a coil for generating a standard magnetic field, a current of 1A is passed through the coil to generate a magnetic field of 10000nT, and the magnetic current conversion coefficient of the coil is k=10000nT / A; a high-sensitivity magneto-impedance sensor is placed at the exact center of the coil in the shielding tank, a current is passed through the coil from -1A to 1A, and the output voltage value corresponding to the high-sensitivity magneto-impedance sensor is recorded at intervals of 100mA; a linear fit is performed with the output voltage value of the high-sensitivity magneto-impedance sensor as the y-axis and the magnetic field value of the environment in which it is located as the x-axis, and the slope obtained is the magnetic voltage conversion coefficient of the high-sensitivity magneto-impedance sensor, and its unit is V / T.

[0011] The above-mentioned magnetic impedance gradient current sensor current measurement and positioning method is specifically as follows: a conductor through which the measured current passes is placed in the internal structure of four high-sensitivity magnetic impedance sensors arranged at different positions; the high-sensitivity magnetic impedance sensors sense the magnetic field around the conductor; the output voltage values ​​of the four high-sensitivity magnetic impedance sensors are respectively collected by a multimeter, which are recorded as V1, V2, V3, and V4; and then the output voltage value of each high-sensitivity magnetic impedance sensor and its corresponding magnetic voltage conversion coefficient S are converted by formula B i =V i / S (where (i=1,2,3,4)) is calculated to obtain the magnetic field strength values ​​at four high-sensitivity magneto-impedance sensors, and the obtained magnetic field strength data is uploaded to the host computer through the communication interface. In the host computer, the mathematical relationship between current and magnetic field distribution is used to analyze the data through an algorithm to determine the size of the measured current and its spatial position. Finally, the host computer outputs the measured current value and its specific position in real time; in the host computer program, the magnetic voltage conversion coefficient value of each high-sensitivity magneto-impedance sensor is pre-entered.

[0012] The magnetic impedance gradient current sensor used in the above-mentioned magnetic impedance gradient current sensor current measurement and positioning method includes four high-sensitivity magnetic impedance sensors with the same characteristics placed around the conductor through which the current to be measured flows, two of which are placed on the x-axis and two on the y-axis. Specifically, with (0, 0) as the origin, a high-sensitivity magnetic impedance sensor is placed at each of the four points (-R, 0), (R, 0), (0, -R), and (0, R), and the sensing direction of the high-sensitivity magnetic impedance sensor is perpendicular to the conductor.

[0013] The four high-sensitivity magneto-impedance sensors of the magneto-impedance gradient current sensor are magneto-impedance sensors made of amorphous wire as raw material.

[0014] The magneto-impedance gradient current sensor also includes a U-shaped frame, on which four positions for placing high-sensitivity magneto-impedance sensors are arranged, and the four positions for placing high-sensitivity magneto-impedance sensors are arranged according to (-R, 0), (R, 0), (0, -R), and (0, R).

[0015] Principle of the present invention: The conductor through which the measured current passes is placed in the internal structure of the magneto-impedance gradient current sensor. The output voltage values ​​V1, V2, V3, and V4 of the four high-sensitivity magneto-impedance sensors are obtained by placing high-sensitivity magneto-impedance sensors at four points (-R, 0), (R, 0), (0, -R), and (0, R) with (0, 0) as the origin. The magnetic voltage conversion coefficients of the four high-sensitivity magneto-impedance sensors are recorded as S. B is calculated by the above formula. a , B b , B c , B d The values ​​of and B1, B2, B3, B4, square both sides of the equations for B1, B2, B3, B4, and let: , after substituting into the equation, the equation becomes: , Solving for x0 Take the first two equations and subtract them to eliminate : , expand and simplify: , , and we get: ; Solve y0 in the same way:

[0016] Solution

[0017] Depend on B 1 Equation is transformed to obtain , bring in x 0 and y Transformation expression of 0 ,get: ,Will C 1. C 2. C 3. C Substituting 4 into the equation, we get: , set B1=B a =V1 / S、B2=B b =V2 / S、B3=B c =V3 / S、B4=B d=V4 / S Substituting back, we get: , ;

[0018] The above derivation proves the feasibility of the measurement method. The physical mechanism behind it is correct. The current value and its position parameter expression are obtained through the Ampere loop theorem and the quantitative relationship between the test values ​​of the high-sensitivity magneto-impedance sensor.

[0019] The above is the theoretical basis for measuring the current size and position using a magneto-impedance gradient current sensor. By simply measuring the output voltage value of the high-sensitivity magneto-impedance sensor and its magneto-voltage conversion coefficient, the expression of the current value to be measured and its position parameter can be obtained based on the theory.

[0020] Therefore, as long as the output voltage of the four high-sensitivity magneto-impedance sensors is measured and divided by the magnetic voltage conversion coefficient output by the high-sensitivity magneto-impedance sensor, the magnetic field strength values ​​at the four high-sensitivity magneto-impedance sensors can be obtained. By calculating through the theoretical formula input by the host computer, the current value to be measured and its position value can be obtained and collected and read by the host computer.

[0021] The present invention uses a high-sensitivity magneto-impedance sensor to construct a magneto-impedance gradient current sensor. By simultaneously measuring the magnetic field values ​​generated by the current at several positions, the current value can be measured with high precision while the current location can be determined. Not only can the sensitivity and resolution in the current test be significantly improved, but also the current value and its position can be detected with higher precision. At the same time, the position and size of the measured current can be accurately calculated without contacting or damaging the current conductor, and the usage scenarios are more extensive. A measurement method derived and demonstrated by physical deduction is used to obtain the current value and position of the measured current, and the measurement method is simple enough, and only a common device, a multimeter, is required.

[0022] The magneto-impedance gradient current sensor of the present invention has its advantages in different practical application scenarios. The advantages are explained below from several application scenarios: (1) In modern smart homes, the power monitoring system can help users understand the power consumption of various electrical appliances in the home. It has high compatibility and does not damage home wiring: the magneto-impedance gradient current sensor is U-shaped and can be directly clamped on the outside of the meter box or the power supply line of the electrical appliance without removing the existing circuit, and is adapted to the existing home power system: it can perform high-precision detection of the invisible wire current inside the home wall, determine the specific location of the damaged wire, and accurately handle the problematic wire, thereby reducing the damage to the wall or the housing of the home appliance during the maintenance process; for ordinary users, the non-invasive design reduces the technical threshold of the installation process, and the operation can be completed without professional electrician skills. (2) Power grid operation and maintenance personnel need to monitor the load distribution and abnormal current of the distribution line to ensure the stability of the power grid operation. The magneto-impedance gradient current sensor supports rapid deployment on multiple distribution nodes for analyzing current distribution, avoiding a lot of time spent on traditional sensor installation. The magneto-impedance gradient current sensor has high sensitivity and supports anomaly detection. It can quickly capture current anomalies (such as overcurrent, leakage, etc.), helping operation and maintenance personnel to locate fault points in time. (3) Monitoring of new energy vehicle charging piles: With the popularization of new energy vehicles, the demand for current detection of charging piles has increased, such as the need to monitor charging current, prevent overcurrent or ensure measurement accuracy. Improve detection efficiency: The non-invasive magneto-impedance gradient current sensor can measure current without destroying the charging pile, which is particularly suitable for subsequent installation or upgrade. Strong mobility and support for flexible debugging: During the installation and maintenance of the charging pile, the non-invasive magneto-impedance gradient current sensor is easy to install, disassemble or debug quickly without disassembling the internal electrical system of the charging pile. High detection accuracy, high-precision detection of small currents is also possible. (4) In the laboratory, researchers need to test new equipment or circuit designs, but need to minimize interference with the circuit itself. The magneto-impedance gradient current sensor can avoid interference, and the performance of the circuit under test remains unchanged: The magneto-impedance gradient current sensor does not have direct contact with the circuit under test, so it will not affect the impedance characteristics or electrical parameters of the circuit, ensuring the accuracy of the test data. The magneto-impedance gradient current sensor can be used flexibly in different experimental equipment and test scenarios, greatly improving the efficiency and convenience of research and development. (5) Photovoltaic power generation equipment usually needs to monitor the output current of each group of photovoltaic panels or inverters to ensure system efficiency. The magneto-impedance gradient current sensor is suitable for multi-circuit systems: Photovoltaic power generation systems usually contain multiple groups of lines, and the magneto-impedance gradient current sensor can simplify the monitoring of complex circuits. (6) In power monitoring of substations, industrial equipment and distribution cabinets, the current of running equipment can be monitored to detect faults or evaluate energy consumption. The magneto-impedance gradient current sensor completes current detection by clamping without cutting the line or directly contacting the conductor.The risk of direct operation of high voltage or high current is avoided, and the potential safety hazards in the maintenance process of the power system are greatly reduced. At the same time, since there is no need for power outage for installation, real-time online monitoring can be achieved: the sensor layout is completed when the equipment is in operation, and the power system is monitored in real time, avoiding the downtime and production interruption caused by the installation of traditional wired current sensors. (7) Industrial equipment in factories usually requires distributed monitoring of current, analysis of energy consumption of different equipment, and optimization of energy-saving solutions. This magneto-impedance gradient current sensor can be easily clamped on the outside of the cable without disassembling the equipment or modifying the existing electrical system. This is particularly important in industrial environments with complex wiring and limited space. It can be quickly deployed at multiple points. The magneto-impedance gradient current sensor does not require complex electrical wiring operations and can be quickly distributed on multiple cables, greatly saving time and labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the magneto-impedance gradient current sensor of the present invention. DETAILED DESCRIPTION

[0024] A method for measuring current and its position using a magnetic impedance gradient current sensor, comprising four high-sensitivity magnetic impedance sensors with the same characteristics and placed around the conductor through which the current to be measured flows, and a U-shaped frame 1, wherein four positions for placing high-sensitivity magnetic impedance sensors 2 are arranged on the U-shaped frame 1, and the four positions for placing high-sensitivity magnetic impedance sensors are arranged according to (-R, 0), (R, 0), (0, -R), and (0, R). Four high-sensitivity magnetic impedance sensors with the same characteristics are placed on the U-shaped frame 1, wherein two are placed on the x-axis and two are placed on the y-axis. The four high-sensitivity magnetic impedance sensors are magnetic impedance sensors prepared using amorphous wire as raw materials.

[0025] The method for measuring current and its position by the magneto-impedance gradient current sensor has the following specific steps: (1) Take a section of copper wire and pass a 5A DC current through it using a current source. (2) Pass the energized copper wire vertically through the magneto-impedance gradient current sensor, where the positions of the four high-sensitivity magneto-impedance sensors are set as (-R, 0), (R, 0), (0, -R), (0, R), the R value is 0.05 m, and the copper wire position is (0.01 m, 0.03 m); (3) Connect the outputs of four high-sensitivity magnetic impedance sensors to a multimeter respectively. The high-sensitivity magnetic impedance sensor senses the magnetic field generated by the energized wire and outputs the voltage value to the multimeter. (4) Four multimeters were connected to the host computer. The magnetic voltage conversion coefficients of four high-sensitivity magneto-impedance sensors were pre-input into the host computer. The program control was realized through the serial port communication of the LabVIEW program. The output current value was I=4.94 A, and the values ​​of the output positions x0 and y0 were 0.0101 m and 0.0299 m, respectively. The values ​​obtained by the test were basically the same as the actual set values. The magneto-impedance gradient current sensor can achieve the expected function.

[0026] The magnetic voltage conversion coefficient of the high-sensitivity magneto-impedance sensor is determined as follows: take a magnetic shielding tank, in which there is a coil for generating a standard magnetic field. A current of 1A is passed through the coil to generate a magnetic field of 10000nT. The magnetic current conversion coefficient of the coil is k=10000nT / A. The high-sensitivity magneto-impedance sensor is placed at the center of the coil in the shielding tank, and a current is passed through the coil from -1A to 1A. The output voltage value of the high-sensitivity magneto-impedance sensor is recorded at intervals of 100mA. A linear fit is performed with the output voltage value of the high-sensitivity magneto-impedance sensor as the y-axis and the magnetic field value of the environment in which it is located as the x-axis. The slope obtained is the magnetic voltage conversion coefficient of the high-sensitivity magneto-impedance sensor, and its unit is V / T.

Claims

1. A method for measuring current and positioning using a magnetic impedance gradient current sensor, characterized in that: Four high-sensitivity magneto-impedance sensors with the same characteristics are placed around the conductor through which the current to be measured flows, two of which are placed on the x-axis and two on the y-axis, and the sensing direction of the high-sensitivity magneto-impedance sensors is perpendicular to the conductor; when the current flows through the conductor, due to the Ampere loop theorem, a magnetic field perpendicular to the conductor is generated around the conductor, and the magnetic field strength values ​​B1, B2, B3, and B4 at the locations of the four high-sensitivity magneto-impedance sensors are obtained by the Ampere loop theorem. At the same time, the four high-sensitivity magneto-impedance sensors respectively measure the magnetic field strength values ​​B at their locations. a , B b , B c , B d , by B a =B1, B b =B2, B c =B3, B d =B4, the four equations give the current value I flowing through the wire and the position of the current (x0, y0).

2. A method for measuring current and positioning using a magnetic impedance gradient current sensor according to claim 1, characterized in that: Taking (0, 0) as the origin, a high-sensitivity magneto-impedance sensor is placed at four points: (-R, 0), (R, 0), (0, -R), and (0, R).

3. A method for measuring current and positioning using a magneto-impedance gradient current sensor according to claim 1 or 2, characterized in that: The output voltage value range of the high-sensitivity magnetoimpedance sensor is between -12V and +12V. For every 5.56uT change in the ambient magnetic field of the high-sensitivity magnetoimpedance sensor, its output value changes by 1V. The magnetic voltage conversion coefficient of the high-sensitivity magnetoimpedance sensor is 180000V / T, denoted as S.

4. A method for measuring current and positioning using a magnetic impedance gradient current sensor according to claim 3, characterized in that: For a fixed magnetic field strength value, the high-sensitivity magneto-impedance sensor senses the magnetic field generated by the conductor and outputs a DC voltage value, which is recorded as V1, V2, V3, and V4. The magnetic voltage conversion coefficient of the four high-sensitivity magneto-impedance sensors is S, and the unit is V / T. The DC voltage value output by the high-sensitivity magneto-impedance sensor is divided by its magnetic voltage conversion coefficient to obtain the magnetic field strength value B after the high-sensitivity magneto-impedance sensor. a , B b , B c , B d , then: B a = V1 / S, B b = V2 / S, B c = V3 / S, B d = V4 / S.

5. A method for measuring current and positioning using a magneto-impedance gradient current sensor according to claim 1 or 4, characterized in that: According to Ampere's circuit theorem: , where B represents the magnetic field strength, the unit is Tesla, T; μ 0 is the vacuum permeability, which is μ 0=4π*10 -7 H / m, I0 represents the current intensity, the unit is ampere, A; r is the distance between the high-sensitivity magnetic impedance sensor and the straight line where the current is located, the unit is meter, m; with (0, 0) as the origin, high-sensitivity magnetic impedance sensors are placed at four points (-R, 0), (R, 0), (0, -R), and (0, R), and R is the distance between each high-sensitivity magnetic impedance sensor and the origin; the flow position of the current to be measured is (x0, y0), and the current value to be measured is I. According to the above formula, the magnetic field intensity values ​​generated by the current to be measured at the four positions are: , , , , solving the corresponding equations yields: , , substitute μ 0, R, π, V1, V2, V3, V4, and S, then determine the current value I and position (x0, y0) of the conductor to be tested.

6. A method for measuring current and positioning using a magneto-impedance gradient current sensor according to claim 3, characterized in that: The magnetic voltage conversion coefficient of the high-sensitivity magneto-impedance sensor is determined as follows: a magnetic shielding tank is taken, in which there is a coil for generating a standard magnetic field, a current of 1A is passed through the coil to generate a magnetic field of 10000nT, and the magnetic current conversion coefficient of the coil is k=10000nT / A; a high-sensitivity magneto-impedance sensor is placed at the exact center of the coil in the shielding tank, a current is passed through the coil from -1A to 1A, and the output voltage value corresponding to the high-sensitivity magneto-impedance sensor is recorded at intervals of 100mA; a linear fit is performed with the output voltage value of the high-sensitivity magneto-impedance sensor as the y-axis and the magnetic field value of the environment in which it is located as the x-axis, and the slope obtained is the magnetic voltage conversion coefficient of the high-sensitivity magneto-impedance sensor, and its unit is V / T.

7. A method for measuring current and positioning using a magneto-impedance gradient current sensor according to claim 1 or 6, characterized in that The specific method is to place the wire through which the measured current passes in the internal structure of four high-sensitivity magneto-impedance sensors arranged at different positions. The high-sensitivity magneto-impedance sensors sense the magnetic field around the wire. The output voltage values ​​of the four high-sensitivity magneto-impedance sensors are collected by a multimeter, recorded as V1, V2, V3, and V4, and then the output voltage value of each high-sensitivity magneto-impedance sensor and its corresponding magnetic voltage conversion coefficient S are converted by formula B. i =V i / S (where (i=1,2,3,4)) is calculated to obtain the magnetic field strength values ​​at four high-sensitivity magneto-impedance sensors, and the obtained magnetic field strength data is uploaded to the host computer through the communication interface. In the host computer, the mathematical relationship between current and magnetic field distribution is used to analyze the data through an algorithm to determine the size of the measured current and its spatial position. Finally, the host computer outputs the measured current value and its specific position in real time; in the host computer program, the magnetic voltage conversion coefficient value of each high-sensitivity magneto-impedance sensor is pre-entered.

8. A magneto-impedance gradient current sensor used in a method for measuring current and positioning magneto-impedance gradient current sensor as claimed in any one of the above claims, characterized in that: The invention comprises four high-sensitivity magneto-impedance sensors with the same characteristics placed around the conductor through which the current to be measured flows, two of which are placed on the x-axis and two on the y-axis. Specifically, with (0, 0) as the origin, a high-sensitivity magneto-impedance sensor is placed at four points, namely (-R, 0), (R, 0), (0, -R), and (0, R), respectively, and the sensing direction of the high-sensitivity magneto-impedance sensor is perpendicular to the conductor.

9. The magneto-impedance gradient current sensor used in the current measurement and positioning method of magneto-impedance gradient current sensor according to claim 8, characterized in that: The four high-sensitivity magneto-impedance sensors of the magneto-impedance gradient current sensor are magneto-impedance sensors made of amorphous wire as raw material.

10. The magneto-impedance gradient current sensor used in the current measurement and positioning method of magneto-impedance gradient current sensor according to claim 9, characterized in that: It comprises a U-shaped frame (1), wherein four positions for placing high-sensitivity magneto-impedance sensors (2) are arranged on the U-shaped frame (1), and the four positions for placing the high-sensitivity magneto-impedance sensors are arranged according to (-R, 0), (R, 0), (0, -R), and (0, R).

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