CN106990372A - A kind of magnetic nuclear resonance radio frequency antenna circuit and its impedance matching methods - Google Patents
A kind of magnetic nuclear resonance radio frequency antenna circuit and its impedance matching methods Download PDFInfo
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- CN106990372A CN106990372A CN201610037087.9A CN201610037087A CN106990372A CN 106990372 A CN106990372 A CN 106990372A CN 201610037087 A CN201610037087 A CN 201610037087A CN 106990372 A CN106990372 A CN 106990372A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
- G01N24/081—Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/18—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging
- G01V3/32—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging operating with electron or nuclear magnetic resonance
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Abstract
The present invention provides a kind of magnetic nuclear resonance radio frequency antenna circuit and its impedance matching methods.The antenna circuit includes：Series resonant tank, it includes the radio frequency antenna element being connected in series, tuning capacitance unit and resistance unit；Radio-frequency power amplifier, it is used to carry out power amplification processing to input pulse signal；Radio-frequency transformer, its main coil is connected with the series resonant tank, is connected from coil with the radio-frequency power amplifier；Wherein, the capacitance values of tuning capacitance unit determine the resonant frequency of the magnetic nuclear resonance radio frequency antenna circuit, and the turn ratio of principal and subordinate's coil and/or the impedance value of resistance unit determine the impedance of the magnetic nuclear resonance radio frequency antenna circuit.The application can realize the relatively independent regulation of resonant frequency and impedance, simplify the impedance matching methods of NMR system antenna circuit.
Description
Technical field
The present invention relates to oil and gas development and Exploration Domain, specifically, be related to it is a kind of be used for nuclear magnetic resonance logging and
The radio-frequency antenna circuit and its impedance matching methods of lithologic analysis.
Background technology
The self-rotating nuclear of nuclear magnetic resonance logging and lithologic analysis apparatus measures from rock in the earth formation, typically H members
The amplitude and decay coefficient of the NMR signal of the proton of element.The amplitude of initial signal mainly indicates total porosity
Size, and exponential disintegration is decomposed into time decay, represents spin spinrelaxation.Relaxation time 1~2 is
The measurement of spin-spin interaction, it provides the pore-size about formation, fluid type and permeability.
These parameters are important rock physicses amounts, and this is also the reason for nuclear-magnetism is widely used in well logging, well logging field.
The measurement accuracy of nuclear magnetic resonance logging and lithologic analysis instrument is very sensitive to the noise ratio of measured signal.
Signal to noise ratio is main by the intensity of magnetostatic field, the intensity of radiofrequency field and the two relative bearings in sensitive zones
It is determined that.Among a measurement process, radiofrequency field is used to magnetization reversal (to be typically normal to another face
Magnetostatic field direction), to generate NMR signal in reception antenna.Nuclear magnetic logging and lithologic analysis instrument
The radio-frequency antenna used is usually operated at 400KHz-40MHz.
In order to effectively trigger nmr phenomena generation, it is necessary to produce very strong rf power signal, therefore work(
Rate amplifier, Antenna Impedance Matching and resonant frequency adjustment are essential.Power amplifier, Antenna Impedance Matching
The mutual cooperation adjusted with resonant frequency, the final power output signal that constant gain is provided, and can be to pulse
Input signal is amplified.Prior art realized mostly using the series-parallel mode of multiple electric capacity impedance matching and
Resonant frequency adjustment has been reached using needs.
In order to realize the nmr experiments of a variety of pulse trains, power amplifier, Antenna Impedance Matching and resonance
Frequency adjustment needs to meet the application requirement of distinct methods, and reduces energy expenditure as far as possible, increases stability.
Fig. 1 and Fig. 2 is the structure of existing impedance matching and resonant frequency regulating circuit.Using multiple electric capacity connection in series-parallel
Mode realize that impedance matching and resonant frequency adjustment have been reached using needs.But asking of existing of this method
Topic is, when reconciling any one electric capacity, while all having an impact to impedance and resonant frequency.Therefore mix up in the ban
After resonant frequency, then resistance trimming it is anti-when, resonant frequency changes again does not reach requirement, or otherwise also
So.This mode needs the two or more electric capacity of continuous iteration to reach the mesh of preferable resonant frequency and impedance
's.So regulation gets up very cumbersome, and due to the limitation of precision when electric capacity is adjusted in itself, is extremely difficult to reason
The effect thought.
Therefore, need badly it is a kind of independently can carry out respectively impedance matching and resonant frequency adjustment radio-frequency antenna electricity
Road.
The content of the invention
It is an object of the invention to solve the radio-frequency antenna circuit resistance of the prior art for nuclear magnetic resonance log
Anti- and tuned frequency can not be separately adjustable technological deficiency.
The present invention provides a kind of magnetic nuclear resonance radio frequency antenna circuit, including：
Series resonant tank, it includes the radio frequency antenna element being connected in series, tuning capacitance unit and resistance unit；
Radio-frequency power amplifier, it is used to carry out power amplification processing to input pulse signal；
Radio-frequency transformer, its main coil is connected with the series resonant tank, is put from coil with the radio-frequency power
Big device connection；
Wherein, the capacitance values of tuning capacitance unit determine the resonance frequency of the magnetic nuclear resonance radio frequency antenna circuit
Rate, and the turn ratio of principal and subordinate's coil and/or the impedance value of resistance unit determine the magnetic nuclear resonance radio frequency day
The impedance of line circuit.
In one embodiment, the first end of the main coil of the radio-frequency transformer connects the tuning capacitance unit
First end, the second end of the tuning capacitance unit connects the first end of the radio frequency antenna element, described to penetrate
Second end of frequency antenna element connects the first end of the resistance unit, the second end connection institute of the resistance unit
State the second end of the main coil of radio-frequency transformer.
In one embodiment, the tuning capacitance unit includes adjustable condenser.
In one embodiment, when the magnetic nuclear resonance radio frequency antenna circuit is operated in resonant condition, under
State expression formula adjustment resonant frequency：
Wherein, L represents the built-in inductance of radio frequency antenna element, and C represents the electric capacity of tuning capacitance unit, ω tables
Show resonant frequency.
In one embodiment, when the magnetic nuclear resonance radio frequency antenna circuit is operated in resonant condition, the core
The equiva lent impedance of magnetic resonance radio frequency antenna circuit is：
Wherein, Z0Represent the input impedance from coil, RcRepresent the impedance of resistance unit, NSRepresent from coil
The number of turn, NPRepresent the number of turn of main coil.
According to another aspect of the present invention, a kind of impedance matching methods are also provided, penetrated for above-mentioned nuclear magnetic resonance
Frequency antenna circuit, this method includes：
The electric capacity of regulation tuning capacitance unit causes series resonant tank to be operated in default resonant frequency；
The turn ratio of principal and subordinate's coil and/or the impedance value of resistance unit for adjusting radio-frequency transformer determine institute
State the impedance of magnetic nuclear resonance radio frequency antenna circuit.
In one embodiment, the step of adjusting the impedance of the magnetic nuclear resonance radio frequency antenna circuit and regulation are described
The step of resonant frequency of magnetic nuclear resonance radio frequency antenna circuit, is mutually independent.
In one embodiment, include the step of the impedance of the magnetic nuclear resonance radio frequency antenna circuit is adjusted：
Adjust the main coil number of turn of radio-frequency transformer and/or from coil turn.
Embodiments of the invention determine resonant frequency first, and need to only adjust the size of an electric capacity just can adjust it is humorous
Vibration frequency.After resonant frequency regulation is completed, its impedance is measured, then adjust the turn ratio of resistance and transformer
To adjust optimal impedance.So as to realize the relatively independent regulation of resonant frequency and impedance, simplify nuclear-magnetism
The impedance matching methods of resonator system antenna circuit.
In addition, being limited by electric capacity itself opering characteristic of electric apparatus, the degree of regulation of usual electric capacity can not meet nuclear-magnetism
The impedance matching requirements of resonator system.Embodiments of the invention avoid utilizing capacitance adjustment matching impedance, but logical
Cross the turn ratio for the principal and subordinate's coil for setting radio-frequency transformer to adjust matching impedance, disclosure satisfy that system is flexibly set
The demand of impedance.
Other features and advantages of the present invention will be illustrated in the following description, also, partly from specification
In become apparent, or by implement the present invention and understand.The purpose of the present invention and other advantages can pass through
Specifically noted structure is realized and obtained in specification, claims and accompanying drawing.
Brief description of the drawings
Accompanying drawing is used for providing a further understanding of the present invention, and constitutes a part for specification, with the present invention
Embodiment be provided commonly for explain the present invention, be not construed as limiting the invention.In the accompanying drawings：
Fig. 1 is the circuit theory diagrams for adjusting resonant frequency and matching impedance using capacitance network in the prior art；
Fig. 2 is another circuit theory for adjusting resonant frequency and matching impedance using capacitance network in the prior art
Figure；
Fig. 3 is the principle schematic diagram of the magnetic nuclear resonance radio frequency antenna circuit of the embodiment of the present invention；
Fig. 4 is a preferred exemplary of the magnetic nuclear resonance radio frequency antenna circuit of the embodiment of the present invention.
Embodiment
To make the object, technical solutions and advantages of the present invention clearer, the present invention is implemented below in conjunction with accompanying drawing
Example is described in further detail.
Embodiments of the invention provide a kind of nuclear magnetic resonance for nuclear magnetic resonance logging and lithologic analysis process and penetrated
Frequency antenna circuit.The structure of the radio-frequency antenna circuit is described in detail referring to Fig. 3.
The radio-frequency antenna circuit mainly includes series resonant tank 31, radio-frequency power amplifier 32 and radio frequency transformation
Device 33.Wherein, series resonant tank includes the radio frequency antenna element 311 being connected in series, tuning capacitance unit 312
With resistance unit 313.
Radio-frequency power amplifier 32 is used to carry out power amplification processing to input pulse signal.Radio-frequency transformer 33
Main coil be connected with series resonant tank 31, be connected from coil with radio-frequency power amplifier 32.When nuclear-magnetism is common
When the radio-frequency antenna circuit that shakes is operated in resonant condition, only radio-frequency power amplifier 32 and series resonant tank 31
Realize that impedance matching and resonance could provide input pulse sequence stable gain.
In Fig. 3 antenna circuit, the capacitance values of tuning capacitance unit determine the magnetic nuclear resonance radio frequency antenna
The resonant frequency of circuit, and the turn ratio of principal and subordinate's coil and/or the impedance value of resistance unit determine the core
The impedance of magnetic resonance radio frequency antenna circuit.It should be noted that size and change by adjusting resistance unit impedance
Principal and subordinate's coil ratio of depressor determines the impedance of whole antenna circuit, and the adjustment of the two parameters do not interfere with
Resonant frequency.The relatively independent regulation of resonant frequency and impedance can be realized, this is to improving NMR system
Performance is highly beneficial.
Specifically, the first of the first end connection tuning capacitance unit 312 of the main coil of radio-frequency transformer 33
End, the second end of tuning capacitance unit 312 connects the first end of radio frequency antenna element 311, radio frequency antenna element
311 the second end connects the first end of resistance unit 313, the second end connection radio frequency transformation of resistance unit 313
Second end of the main coil of device 33.It is preferred that, tuning capacitance unit 312 includes adjustable condenser, in order to
Flexible modulation capacitance values.
Fig. 4 is a preferred exemplary of the magnetic nuclear resonance radio frequency antenna circuit of the embodiment of the present invention.Referring to figure
4 pairs of impedance matching methods are described in detail.
The electric current I of radio-frequency transformer main coilPWith the electric current I from coilSFunctional relation can use following expression
Represent：
Wherein, NPFor the number of turn of main coil, NSFor from the number of turn of coil.
Similar, the voltage V of the main coil of radio-frequency transformerPWith the voltage V from coilSFunctional relation can be with
Represented with following expression：
The input impedance Z entered in terms of coil-end can be calculated by expression formula (1) and (2)SExpression function such as
Under：
Wherein, ZPRepresent the impedance at main coil two ends.By expression formula (3) as can be seen that in terms of coil-end
The input impedance entered, which same can be crossed, to be changed main coil or is adjusted from the number of turn of coil.For the electricity in Fig. 4
Line structure, can be further by the input impedance Z entered in terms of coil-endSIt is expressed as：
When producing resonance,
And the equiva lent impedance of the magnetic nuclear resonance radio frequency antenna circuit is when producing resonance：
Wherein, L represents the built-in inductance of radio frequency antenna element, and C represents the electric capacity of tuning capacitance unit, ω tables
Show resonant frequency, Z0Represent the input impedance from coil, RcRepresent the impedance of resistance unit, NSRepresent from line
The number of turn of circle, NPRepresent the number of turn of main coil.
In general, resonant frequency range is 400KHz-40MHz, it can be adjusted using expression formula (5)
The electric capacity of humorous capacitor cell sets resonant frequency.
The regulation of resonant frequency and the calculating of matching impedance are relative it can be seen from expression formula (5) and (6)
Independent process.
Based on above-mentioned analysis process, the detailed process of impedance matching methods provided in an embodiment of the present invention is：First adjust
The electric capacity of section tuning capacitance unit causes series resonant tank to be operated in default resonant frequency；Radio frequency change is adjusted again
The turn ratio of principal and subordinate's coil and/or the impedance value of resistance unit of depressor determine the magnetic nuclear resonance radio frequency
The impedance of antenna circuit.Wherein, the step of adjusting the impedance of the magnetic nuclear resonance radio frequency antenna circuit and regulation institute
The step of stating the resonant frequency of magnetic nuclear resonance radio frequency antenna circuit is mutually independent.Adjusting the magnetic nuclear resonance radio frequency day
The step of impedance of line circuit, includes adjusting the main coil number of turn of radio-frequency transformer and/or from coil turn.
So, after resonant frequency is adjusted, then the size and transformer of resistance are adjusted by adjusting impedance
Principal and subordinate's coil ratio determines the impedance of whole circuit, and the adjustment of the two parameters do not interfere with resonant frequency.
So as to avoid the complicated processes of the continuous iterative processing occurred in the prior art.
While it is disclosed that embodiment as above, but described content is only to facilitate understand the present invention
And the embodiment used, it is not limited to the present invention.Technology people in any the technical field of the invention
Member, on the premise of spirit and scope disclosed in this invention are not departed from, can implementation formal and details
On make any modification and change, but the scope of patent protection of the present invention still must be with appended claims institute
The scope defined is defined.
Claims (8)
1. a kind of magnetic nuclear resonance radio frequency antenna circuit, it is characterised in that including：
Series resonant tank, it includes the radio frequency antenna element being connected in series, tuning capacitance unit and resistance unit；
Radio-frequency power amplifier, it is used to carry out power amplification processing to input pulse signal；
Radio-frequency transformer, its main coil is connected with the series resonant tank, is put from coil with the radio-frequency power
Big device connection；
Wherein, the capacitance values of tuning capacitance unit determine the resonance frequency of the magnetic nuclear resonance radio frequency antenna circuit
Rate, and the turn ratio of principal and subordinate's coil and/or the impedance value of resistance unit determine the magnetic nuclear resonance radio frequency day
The impedance of line circuit.
2. magnetic nuclear resonance radio frequency antenna circuit as claimed in claim 1, it is characterised in that
The first end of the main coil of the radio-frequency transformer connects the first end of the tuning capacitance unit, the tune
Second end of humorous capacitor cell connects the first end of the radio frequency antenna element, the second of the radio frequency antenna element
The first end of the end connection resistance unit, the second end of the resistance unit connects the master of the radio-frequency transformer
Second end of coil.
3. magnetic nuclear resonance radio frequency antenna circuit as claimed in claim 1, it is characterised in that
The tuning capacitance unit includes adjustable condenser.
4. the magnetic nuclear resonance radio frequency antenna circuit as any one of claim 1-3, it is characterised in that
When the magnetic nuclear resonance radio frequency antenna circuit is operated in resonant condition, resonance is adjusted according to expressions below
Frequency：
Wherein, L represents the built-in inductance of radio frequency antenna element, and C represents the electric capacity of tuning capacitance unit, ω tables
Show resonant frequency.
5. magnetic nuclear resonance radio frequency antenna circuit as claimed in claim 4, it is characterised in that
When the magnetic nuclear resonance radio frequency antenna circuit is operated in resonant condition, the magnetic nuclear resonance radio frequency antenna electric
The equiva lent impedance on road is：
Wherein, Z0Represent the input impedance from coil, RcRepresent the impedance of resistance unit, NSRepresent from coil
The number of turn, NPRepresent the number of turn of main coil.
6. a kind of impedance matching methods, for the magnetic nuclear resonance radio frequency antenna any one of claim 1-5
Circuit, it is characterised in that this method includes：
The electric capacity of regulation tuning capacitance unit causes series resonant tank to be operated in default resonant frequency；
The turn ratio of principal and subordinate's coil and/or the impedance value of resistance unit for adjusting radio-frequency transformer determine institute
State the impedance of magnetic nuclear resonance radio frequency antenna circuit.
7. impedance matching methods as claimed in claim 6, it is characterised in that the regulation nuclear magnetic resonance is penetrated
The step of the step of impedance of frequency antenna circuit and the resonant frequency of the regulation magnetic nuclear resonance radio frequency antenna circuit
It is mutually independent.
8. impedance matching methods as claimed in claim 6, it is characterised in that adjusting the nuclear magnetic resonance
The step of impedance of radio-frequency antenna circuit, includes：
Adjust the main coil number of turn of radio-frequency transformer and/or from coil turn.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610037087.9A CN106990372B (en) | 2016-01-20 | 2016-01-20 | A kind of magnetic nuclear resonance radio frequency antenna circuit and its impedance matching methods |
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| CN201610037087.9A CN106990372B (en) | 2016-01-20 | 2016-01-20 | A kind of magnetic nuclear resonance radio frequency antenna circuit and its impedance matching methods |
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| CN106990372B CN106990372B (en) | 2019-03-22 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107732457A (en) * | 2017-09-30 | 2018-02-23 | 苏州美柯医疗科技有限公司 | antenna element and array antenna |
| CN108828480A (en) * | 2018-06-05 | 2018-11-16 | 中国石油大学(北京) | Three-dimensional NMR imager array antenna decoupling method and device |
| CN112147554A (en) * | 2020-09-05 | 2020-12-29 | 武汉联影生命科学仪器有限公司 | Frequency matching and tuning device for receiving coil, cryogenic probe and magnetic resonance device |
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| GB832609A (en) * | 1955-02-25 | 1960-04-13 | John Hugh Davey Walton | Improvements in or relating to circuits for testing electrical impedance |
| KR870000174B1 (en) * | 1984-04-30 | 1987-02-13 | 삼성전자부품 주식회사 | Ringing eliminating circuit of fryback trans |
| CN101032971A (en) * | 2007-04-27 | 2007-09-12 | 北京交通大学 | Audio frequency orbit circuit impedance matching circuit in station |
| CN203204140U (en) * | 2013-04-12 | 2013-09-18 | 吉林大学 | Front-end signal conditioning module of receiving system of nuclear magnetic resonance water-researching machine |
| CN204457762U (en) * | 2014-12-31 | 2015-07-08 | 中国石油天然气集团公司 | A kind of high-power transmitting and apparatus for detecting weak signal |
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2016
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB832609A (en) * | 1955-02-25 | 1960-04-13 | John Hugh Davey Walton | Improvements in or relating to circuits for testing electrical impedance |
| KR870000174B1 (en) * | 1984-04-30 | 1987-02-13 | 삼성전자부품 주식회사 | Ringing eliminating circuit of fryback trans |
| CN101032971A (en) * | 2007-04-27 | 2007-09-12 | 北京交通大学 | Audio frequency orbit circuit impedance matching circuit in station |
| CN203204140U (en) * | 2013-04-12 | 2013-09-18 | 吉林大学 | Front-end signal conditioning module of receiving system of nuclear magnetic resonance water-researching machine |
| CN204457762U (en) * | 2014-12-31 | 2015-07-08 | 中国石油天然气集团公司 | A kind of high-power transmitting and apparatus for detecting weak signal |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107732457A (en) * | 2017-09-30 | 2018-02-23 | 苏州美柯医疗科技有限公司 | antenna element and array antenna |
| CN107732457B (en) * | 2017-09-30 | 2024-03-12 | 苏州美柯医疗科技有限公司 | Antenna unit and array antenna |
| CN108828480A (en) * | 2018-06-05 | 2018-11-16 | 中国石油大学(北京) | Three-dimensional NMR imager array antenna decoupling method and device |
| CN112147554A (en) * | 2020-09-05 | 2020-12-29 | 武汉联影生命科学仪器有限公司 | Frequency matching and tuning device for receiving coil, cryogenic probe and magnetic resonance device |
| CN112147554B (en) * | 2020-09-05 | 2023-08-15 | 武汉联影生命科学仪器有限公司 | Frequency and matching tuning device of receiving coil, low-temperature probe and magnetic resonance device |
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| CN106990372B (en) | 2019-03-22 |
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