RU2529448C1 - Three-component magnetometer based on spherical yig resonator and method of detection of full magnetic field vector - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: magnetometer includes microwave generator with a spherical resonator based on an yttrium-iron garnet with three axes of light magnetisation, which are in the generator feedback line, and a magnetic system for transition of the resonator into the saturation mode, representing three inductance coils, which are arranged near the resonator so that their axes of symmetry are aligned along the axes of light magnetisation of the resonator. The outlet of the microwave generator is connected to a frequency meter. Signals from a square-ware generator are sent to coils via a counter of pulses and a demultiplexer, and the square-ware generator is also connected to a frequency meter via an inverter. A signal from the frequency meter via a coupling board is sent to a PC for processing.

EFFECT: increased sensitivity and magnetic directivity of a device, simplified method to determine direction of a magnetic field induction vector or direction to an iron-containing object.

2 cl, 4 dwg

Description

The invention relates to the field of detection of ferrous bodies using electric or magnetic means and navigation on the Earth’s magnetic field, and in particular to devices for measuring the direction and magnitude of magnetic fields using magnetic resonance.

Known vector magnetometer, including three identical flux-gate sensors, schemes for their control and signal processing (see Patent RU 2218577, IPC G01R 33/02). The true direction of the measured magnetic field vector is determined by the equality of the signals from all three flux gates in the case when each of them occupies the same angular position relative to the full magnetic induction vector of the measured magnetic field, and this angular position corresponds to the optimal sensitivity of the flux gates. In this case, it is assumed that the magnetometer needs to be changed to find the direction of the magnetic field vector.

The disadvantages of the magnetometer according to patent RU 2218577 include the significant complexity of the measuring circuit and the need to use identical magnetic field sensors, which is difficult to implement in practice.

A known magnetometer based on an induction magnetic field sensor used to determine the direction of the magnetic field induction vector when searching for iron ore deposits (see Patent RU 2148840, IPC G01V 3/10). After the first measurement and determination of the direction to the object, it is necessary to move the magnetometer, once again use it to determine the new direction to the object and then find the intersection point of the first and second directions, showing the position of the object.

Common disadvantages of the known magnetometers according to the patents RU 2218577 and RU 2148840 are: the need to rotate the magnetometer when determining the direction of the magnetic field or the direction to the ferrous object, inaccuracies in determining the azimuthal angle to the object due to averaging the magnitude of the induction of the investigated magnetic field, because The response signal of the induction and fluxgate sensors is proportional to the flux of the induction vector through the cross section of the measuring inductance coil. Such sensors do not allow to reliably determine the position of the object in the presence of local perturbations of the magnetic field, magnetic interference, and are also not applicable for determining extended objects, several objects, when searching for moving objects, etc.

According to the technical design, the closest to the claimed solution is a one-component magnetometric sensor that allows you to determine one component of an external constant magnetic field (Gurzo V.V. et al. Vector magnetometer of small magnetic fields // Heteromagnetic microelectronics. - Saratov: Publishing house Sarat. Un- ta. 2004. Issue 1. S.50- 52.). The one-component magnetometric sensor includes: a microwave generator using a field or bipolar transistor with an active element and a feedback line; a spherical or film resonator made of iron-yttrium garnet (YIG) as a frequency-setting element, placed in the generator feedback line, a frequency meter, the input of which is connected to the output of the generator; interface card for transmitting frequency measurement results from a frequency meter to a computer. The computer is designed to process the measurement results and calculate the corresponding component of the magnetic field. To transfer the YIG of the resonator into saturation mode, a magnetic system is usually used in the form of a permanent magnet, which creates a field in the resonator region sufficient to bring it into a saturated state. The generator operates at a frequency of ferromagnetic resonance, depending on the magnetization of the resonator, which is also affected by the field from the magnetic system and external induction associated with the constant magnetic field of the Earth or a ferromagnetic object.

However, one sensor allows only one component of the magnetic field vector to be detected. To find the full vector of the magnetic field, such a sensor must be rotated or it is possible to use several (three) sensors at the same time, which must be identical.

The objective of this solution is to develop a magnetometer with a simple design to determine the magnitude and direction of the total induction vector of the Earth’s magnetic field or magnetic field generated by a ferromagnetic object.

The technical result is to increase the sensitivity and magnetic orientation of the device, simplifying the method of determining the direction of the magnetic field induction vector or direction to the ferrous object.

The specified technical result is achieved in that the magnetometer containing a microwave generator with a frequency-setting element in the feedback line, a resonator based on yttrium-iron garnet as a frequency-setting element, a magnetic system for putting the resonator into saturation mode, a frequency meter, the input of which is connected to the microwave output -generator, calculation unit, interface card for transmitting the results of frequency measurements from the frequency meter to the calculation unit, according to the solution, contains a rectangular pulse generator, an inverter, an input to of which is connected to the output of the rectangular pulse generator, and the output is connected to the frequency counter, a spherical resonator with three easy magnetization axes is selected as the resonator, and the magnetic system consists of three inductors connected to the rectangular pulse generator via a pulse counter and a demultiplexer located near the resonator so that their axes of symmetry are oriented along the axes of easy magnetization of the resonator. In a method for determining the magnetic induction vector of an external magnetic field using a microwave generator with a spherical YIG resonator in a feedback line, which includes creating a magnetizing field along the first axis of the easy magnetization of the resonator, measuring the frequency of the generator of the first component of the external magnetic field directed along the first axis of the easy magnetization of the resonator, according to the solution, magnetizing fields are successively created along the second and third axes of easy magnetization of the resonator; Ora measure the second and third components of the external magnetic field directed along the second and third axes of easy magnetization of the resonator, respectively, and determine the vector of the external magnetic field as the vector sum of the three measured components.

на фиг.1) показано расположение катушек индуктивности (1, 2, 3) для формирования в резонаторе (4) вектора намагниченности, ориентированного вдоль одной из трех осей легкого намагничивания (OA, OB, OC на фиг.1); на фиг. 3 показаны компоненты B₁, B₂, B₃ вектора магнитной индукции и полный вектор магнитной индукции B₀ внешнего постоянного магнитного поля; фиг. 4 показывает блок-схему магнитометра, иллюстрирующую работу всего устройства.The invention is illustrated by drawings, where in FIG. 1 shows the relative position of the three axes of easy magnetization (OLS) in a spherical resonator (OA, OB, OC); in FIG. 2 in the projection onto the horizontal plane ( $$A\text{'}\text{'}B\text{'}\text{'}C\text{'}\text{'}$$

figure 1) shows the location of the inductors (1, 2, 3) for the formation in the resonator (4) of the magnetization vector oriented along one of the three axes of easy magnetization (OA, OB, OC in figure 1); in FIG. 3 shows the components B ₁ , B ₂ , B ₃ of the magnetic induction vector and the full magnetic induction vector B _{0 of} an external constant magnetic field; FIG. 4 shows a block diagram of a magnetometer illustrating the operation of the entire device.

The positions in the drawings indicate:

1,2,3 - inductors;

4 - spherical YIG resonator;

5 - a microwave generator controlled by a magnetic field (GUM);

6 - demultiplexer;

7 - pulse counter;

8 - frequency counter;

9 - inverter;

10 - interface card;

11 - calculation unit (computer);

12 - pulse generator.

A magnetometer design is proposed that uses the magnetic properties of YIG crystals, which consist of the existence of three OLIs in them, and the magnetic system of three inductor coils allows you to periodically change the orientation of the magnetization vector in the resonator by 120º (in projection onto a horizontal plane). The use of this invention allows to determine the full vector of the magnetic field induction, or the direction to the center of the ferro-containing body.

The main component of the magnetometer is a generator controlled by a magnetic field. The designs of generators on YIG resonators (spherical or film) are known and are presented in a number of works, for example, in [Solid-state microwave devices in communication technology / Gassanov GL et al. - M.: Radio and Communications, 1988. 288 pp., Khvalin A.L., Vasiliev A.V., Ignatiev A.A., Samoldanov V.N. Research of integrated magnetically controlled generators in the microwave frequency range // Problems of Electromechanics. Proceedings of NPP VNIIEM. 2010.V. 114. No. 1. S. 51-55., Khvalin A.L., Sotov L.S., Ovchinnikov S.V., Kobyakin V.P. Experimental studies of a hybrid integrated magnetically controlled generator // Devices and Systems. Management, control, diagnostics. 2009. No. 11. S.42-44.].

The proposed vector magnetometer based on a spherical resonator (SR) is a microwave generator whose frequency is determined by the frequency of the ferromagnetic resonance of the SR located in its feedback circuit (see, for example, [Khvalin A.L., Vasiliev A.V., Ignatyev A.A., Samoldanov V.N. Research of integrated magnetically controlled generators in the microwave frequency range // Electromechanics Issues. Proceedings of NPP VNIIEM. 2010. V. 114. No. 1. P. 51-55., Khvalin A.L. , Sotov L.S., Ovchinnikov S.V., Kobyakin V.P. Experimental studies of hybrid integral magneto controlled generator // Instruments and systems. Management, control, diagnostics. 2009. No. 11. P.42-44., Gurzo VV et al. Vector magnetometer of small magnetic fields // Heteromagnetic microelectronics. - Saratov: Publishing house Sarat. University. 2004. Issue 1. S.50- 52., Sotov L.S., Khvalin A.L. RF Patent RU 2472182 C1, IPC G01V 3/11. 01/10/2013 Bull. No. 1]).

The invention is based on the use of the magnetic properties of YIG crystals having a cubic structure and three distinguished directions — the easy magnetization axes (see Shaskolskaya MP Crystallography. - M.: Higher school., 1964. 376 p.). When the magnetic field is turned on alternately in the direction of the VLF, the direction of the resonator magnetization vector is set along the corresponding VLF (OA, OB or OC in Fig. 1), which leads to a change in the frequency of the magnetically controlled microwave generator due to differences in the mutual orientation of the magnetization vector of the resonator and the external magnetic vector fields.

The magnetometer contains a microwave generator 5 with a spherical resonator based on yttrium-iron garnet with three axes of easy magnetization as a frequency-setting element 4 in the feedback line, a magnetic system for putting the resonator into saturation mode, which is three inductors 1, 2, 3, located near the resonator so that their axis of symmetry are oriented along the axes of easy magnetization of the resonator. The coils are connected to the square-wave generator 12 through a pulse counter 7 and a demultiplexer 6. The magnetometer contains a frequency meter 8, the input of which is connected to the output of the microwave generator, the calculation unit 11 and the interface card 10 for transmitting the results of frequency measurements from the frequency meter to the calculation unit. The device comprises an inverter 9, the input of which is connected to the output of the rectangular pulse generator 12, and the output is connected to the frequency meter.

The block diagram of the magnetometer is shown in figure 4. In the feedback circuit of the microwave generator 5 controlled by a magnetic field (GUM), there is a resonator 4. Near the SR there are inductors (1, 2 and 3 in Figs. 3 and 4), to which current pulses from the square-wave generator alternately arrive.

Alternately turning on three inductors (see figure 4) is performed using the magnetic control unit of the magnetic system based on simple basic logic circuits (see Klochkov GL Digital devices and microprocessors. - Voronezh: VIRE, 2005. 320 p.) . The sequence of rectangular pulses from the pulse generator 12 is fed to a binary two-digit summing counter 7. At the output of the counter 7, control address binary codes (10, 01, 11) corresponding to three inductors are sequentially generated. After every third pulse, a signal is supplied to the counter (from inductor 3), which returns it to its original state.

The address outputs of the counter are fed to the demultiplexer 6 with two inputs, in which the signals from the inputs are distributed in the desired sequence across three outputs. The selection of the desired output bus is provided by the corresponding code on the address inputs (for example, 01, 10, or 11).

At the same time, in the inductance coils, current pulses are switched on alternately, creating a magnetic field of a certain direction and alternately setting the direction of the resonator magnetization vector in three OLS (OA, OB, OC in FIG. 1).

The input of the frequency meter 8 is connected to the output of the GUM 5, which measures the frequency of the GUM when the start pulse of the frequency meter is received from the output of the inverter 9. From the output of the frequency meter 8, the measured frequency values through the interface card 10, which performs the functions of the interface, are sent to the computer for processing (11). Using the software in the computer, the necessary calculations are performed and the magnitude and direction of the total magnetic induction vector (see Fig. 3) of the external constant magnetic field (B ₀ = B ₁ + B ₂ + B ₃ ) are determined.

на фиг.1 соответствующие углы равны 120˚).The device operates as follows (see figure 4). The rectangular pulse generator 12 with a frequency ν sends current pulses to the inductors 1, 2 and 3. The logic control unit of the magnetic system (blocks 6 and 7) performs the alternating switching of the current pulses in the three inductors. With a pulse duration of the order of 1 ms and an inductance of 1 mH, transients are insignificant and do not require additional adjustment. With the diameter of the superlattice about 0.5 mm, the diameter and length of the inductors 1, 2, and 3 equal to 0.75 mm and 1.5 mm, respectively, a fairly uniform magnetic field of about 200 Gs is created in the region of the superlattice 4. Thus, inductors 1, 2, and 3 alternately create magnetic fields in the CP region along three OLS. In this case, the magnetization vector SR changes directions (in the projection onto the horizontal plane $$A\text{'}\text{'}B\text{'}\text{'}C\text{'}\text{'}$$

1, the corresponding angles are 120 °).

The resulting magnetic field in the SR region will be determined by the sum of the magnetic induction vectors of the external (measured) field B ₀ and field B _i from one of the inductors (1, 2 or 3 in FIG. 4):

B = B ₀ + B _i , where i = 1, 2, 3.

Information on the magnitude of the magnetic induction is contained in the frequency of the GUM 5, which is set by the frequency of the ferromagnetic resonance in the SR and is measured using a frequency meter 8. The magnitude of the magnetic induction is connected with the measured frequency by a simple relation:

f = γ | B |, where γ is the known magnitude of the gyromagnetic ratio.

The start pulses of the frequency meter from the inverter 9 are synchronized with the frequency of switching the direction of the magnetic field ν. Then the signal from the output of the frequency counter 8 through the necessary interface card 10 is supplied for processing in the computer 11.

In the claimed invention, the complete magnetic induction vector B ₀ is found by vector summation of the found components B ₁ , B ₂ and B ₃ (see figure 3).

The presented magnetometer has several advantages in comparison with the known solutions. When determining the position of an object, the “bearing” method is often used, in which several identical sensors determine the azimuthal angles in the direction of the object [Vetoshko P.M. Patent RU 2100819 C1, G01R 33/00, G01R 33/02, G01R 33/05. Claim 09/30/1996. Publ. 12/27/1997; Prishchepov S.K., Valitov K.R. Patent RU 2218577 C2, G01R 33/02 11/09/2001. Publ. 12/10/2003]. Then there is the intersection point of these directions. Another version of this approach is described in [Emelianenko T.I., Takhautdinov R.S., Krasnov S.G., Susoeva G.N. Patent RU 2148840 C1, IPC G01V 3/10, G01V 3/40, G01R 33/02. Claim 09/08/1998. Publ. 05/10/2000. Bull. No. 34]. In the case of [Emelianenko T.I., Takhautdinov R.S., Krasnov S.G., Susoeva G.N. Patent RU 2148840 C1, IPC G01V 3/10, G01V 3/40, G01R 33/02. Claim 09/08/1998. Publ. 05/10/2000. Bull. No. 34] uses one sensor, which must be moved and re-determine the direction of the ferro-containing object. Conventional approaches to solving the problem of locating objects, therefore, must use either identical sensors, or one that needs to be moved.

The inventive microwave generator with a spherical YIG resonator in the feedback line allows you to implement the following method for determining the magnetic induction vector of an external magnetic field. First, a magnetizing field is created along the first axis of the easy magnetization of the resonator, and the first component of the external magnetic field directed along the first axis of the easy magnetization of the resonator is measured by the generator frequency. Then, by analogy, magnetizing fields are successively created along the second and third axes of easy magnetization of the resonator, the second and third components of the external magnetic field are measured by the frequency of the generator, directed along the second and third axes of easy magnetization of the resonator, respectively, after which the vector of the external magnetic field is determined as the vector sum of three measured components.

The solution presented in the invention combines both approaches. The use of magnetic properties of superlattices (see [Smith, J., Wayne H. Ferrites. Physical properties and practical applications. - M .: Publishing house of foreign literature. 1962. 504 p.]), Allowing to change the angle of the magnetization vector of superlattices , creates opportunities for spatial bearing. Using the same GUM solves the problem of sensor identity.

The scope of the invention is not limited to those of FIGS. 1-4, since any changes and additions will be apparent to those skilled in the art. The scope of the invention is limited only by the following claims.

Claims (2)

1. A magnetometer containing a microwave generator with a frequency-setting element in the feedback line, a resonator based on yttrium-iron garnet as a frequency-setting element, a magnetic system for putting the resonator into saturation mode, a frequency meter, the input of which is connected to the output of the microwave generator, a calculation unit , an interface card for transmitting the results of frequency measurements from the frequency meter to the calculation unit, characterized in that it contains a rectangular pulse generator, an inverter, the input of which is connected to the output of the generator pulses, and the output is connected to the frequency counter, a spherical resonator with three axes of easy magnetization is selected as the resonator, and the magnetic system consists of three inductors connected to a rectangular pulse generator via a pulse counter and a demultiplexer located near the resonator so that their axes symmetries were oriented along the axes of easy magnetization of the resonator. 2. A method for determining the magnetic induction vector of an external magnetic field using a microwave generator with a spherical YIG resonator in a feedback line, including creating a magnetizing field along the first axis of easy magnetization of the resonator, measuring the frequency of the generator of the first component of the external magnetic field directed along the first axis of the lung resonator magnetization, characterized in that then magnetizing fields are subsequently created along the second and third axes of the easy magnetization of the resonator, in frequency e of the generator, the second and third components of the external magnetic field are measured, directed along the second and third axes of easy magnetization of the resonator, respectively; the vector of the external magnetic field is determined as the vector sum of the three measured components.

Images