CN108562623A - A kind of sensor and preparation method thereof being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic - Google Patents
A kind of sensor and preparation method thereof being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic Download PDFInfo
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- 239000002689 soil Substances 0.000 title claims abstract description 61
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 title claims abstract description 28
- 239000011780 sodium chloride Substances 0.000 title claims abstract description 14
- 238000002360 preparation method Methods 0.000 title abstract description 3
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- 238000005259 measurement Methods 0.000 claims abstract description 33
- 239000004020 conductor Substances 0.000 claims abstract description 20
- 239000000463 material Substances 0.000 claims abstract description 19
- 229920002521 macromolecule Polymers 0.000 claims abstract description 14
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 13
- 230000001603 reducing effect Effects 0.000 claims abstract description 9
- 229910001220 stainless steel Inorganic materials 0.000 claims description 18
- 239000010935 stainless steel Substances 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 7
- 238000003825 pressing Methods 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 5
- 229910000831 Steel Inorganic materials 0.000 claims description 3
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
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- 238000004422 calculation algorithm Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
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- 239000003673 groundwater Substances 0.000 description 1
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- 238000012625 in-situ measurement Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 238000000643 oven drying Methods 0.000 description 1
- -1 polytetrafluoroethylene Polymers 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
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- 150000003839 salts Chemical class 0.000 description 1
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Abstract
The invention discloses a kind of sensors and preparation method thereof being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic, the center needle of probe body is connect by the impedance transducer that the outer conductor of macromolecule low conductivity material and reducing forms with inner conductor copper core, remaining needle body is parallel with center needle body, is uniformly distributed in using center needle body as on the external circumference of a diameter of S in the center of circle.Advantageous effect is：By adjusting the outer diameter and length of impedance transducer, the input resistant matching of the characteristic impedance and measuring instrument that make impedance transducer is best, avoids blind spot occur in normality region, reduces signal decaying, meets the measurement demand under different condition.In addition, according to different measurements and accuracy requirement, determines suitable impedance transducer length, overcome the defect that adjacent excessively close reflection is difficult to differentiate between, ensure that higher measurement accuracy；On the other hand, the defect that the excessive volume for lengthening caused sensor of impedance transducer increases is also avoided.
Description
Technical field
The present invention relates to a kind of sensors；Being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil more particularly to one kind
Sensor of characteristic and preparation method thereof.
Background technology
Time Domain Reflectometry principle (TDR) is measuring soil in recent years as a kind of conventional instrument method of effective in situ measurement
The dielectric properties such as dielectric constant, conductivity, impedance, and thereby determine that the soil properties such as volumetric water content, salt content, compactness
Aspect is widely used.Its technological core-spread speed of measurement electromagnetic wave in the soil, usually there are two types of modes：
Time domain is without carrier frequency pulse regime and frequency-domain frequency stepping system.
Time Domain Reflectometry principle (Time Domain Reflectometry, TDR) results from last century the '30s, initially
It is used to the damaged location of detection and orientation and communication cable.As last century the seventies find that TDR technologies can measure soil mass
After product water content, it is widely used in agriculture field.And from after the eighties, which gradually sends out to geotechnical engineering field
Exhibition is mainly measuring water content of soil and dry density, monitoring Landslide Stability, is measuring level of ground water and conductivity, the monitoring soil body
Pollution and chemical consolidation soil quality control etc. are applied, and with convenience, safety, economy, digitlization and remote control etc.
Feature and receive significant attention.
When an electromagnetic pulse pumping signal is along transmission line, the interruption of transmission line impaired or periphery substance does not connect
Continuous property can cause the variation of its impedance, the variation of this impedance that the signal of transmission will be caused to generate one at this discontinuity point
A reflection, it is poor by the accurate journey time for measuring electromagnetic wave incident wave and back wave, then it can accurately judge that this does not connect
The position of continuous point.
Meet following relationship between frequency electromagnetic waves spread speed v in the medium and apparent dielectric constant Ka：
Ka=(c/v)2 (1)
Wherein c=3 × 108Meter per second is the light velocity.The famous empirical equation that Canada scholar G.C.TOPP in 1980 is provided is very
Good describes apparent dielectric constant KaRelationship between volumetric soil water content：
This is famous TOPP formula in the industry.
Fig. 1 is that the high frequency electromagnetic wave signal generated by TDR instruments is input to the sensing being inserted into soil by coaxial cable
Device (probe), since the change of impedance generates first pip, electromagnetic wave signal continues to move ahead along sensor (probe), reaches
The probe end that length is L generates the second secondary reflection, and reflection wave signal sends back TDR instruments along sensor, if it is assumed that electromagnetism
Wave is Δ t along the time of sensor transmissions and reflection, then has：(1) formula of substitution, then have：
It can be seen that the key of time domain reflection technology (TDR) is the accurate measurement to the electromagnetic transmission time.
The accurate measurement detection of electromagnetic transmission time is based primarily upon three kinds of systems in transmission line：Time domain is without carrier frequency pulse body
System, CW with frequency modulation system and frequency-domain frequency stepping system, existing TDR instruments mostly use time domain without carrier frequency pulse regime, TDR
Instrument is a time domain simulation system.The basic point of Time Domain Reflectometry principle is the reflection of electromagnetic wave, and the reflection of electromagnetic wave is
The change of impedance when due to its ducting and cause.
In addition, soil disclosed in patent of invention ZL2015103818577 and utility model patent number ZL2015204695813
Moisture teller uses frequency-domain frequency stepping system and is detected to soil.
Frequency-domain frequency stepping system is the generation series of points frequency continuous wave signal of timesharing stepping successively, and frequency reaches as high as
To microwave frequency band.Each simple signal generates the representation signal of excitation incoming signal by coupling, and through connect signal is along coaxial electrical
Cable generates signal reflex, then realize and test by directional couple afterwards to the probe of connection into different medium (soil)
Signal and reflex response Signal separator form reflected received signal.Incident representation signal and reflected received signal are respectively by respective
Receiver receive, and the data of reception are stored, after the frequency scanning of setting, obtained series frequency domain letter
Number by inverse discrete Fourier transform (IDFT) conversion to time domain, to realize the accurate measurement to the electromagnetic transmission time.
Foregoing invention patent is time domain, a frequency domain multiple domain that data analysis is carried out using numerical data and mathematical algorithm
Processing system.Therefore, being taken as the matching used soil detection sensor of frequency-domain frequency stepping system instrument has more
It is required that.
Fig. 2 is simulation of the TDR sensors to coaxial cable applied to Soil Testing, center needle body and coaxial cable
It inside leads copper core to be connected, outside is connect with the outer shielded layer of leading of coaxial cable.
Fig. 3 is TDR sensor needle body sectional views.From structure, TDR sensors are divided into as coaxial-type and multiple-pin type.Due to
Coaxial-type sensor blocked cylinder outer and cylinder in soil exchange of moisture, meanwhile, cause to original in order to avoid plugging in the soil
The disturbance of shape soil, therefore the multiple-pin type sensor (probe) of analog coaxial cable structure is mostly used, more with three in practical application
Based on stylus structure.
Fig. 4 is that soil nmoisture content analyser measures sectional drawing.
The sensor that existing TDR instruments and other soil measuring Instruments use is more, but is not exclusively applicable in
In frequency-domain frequency stepping system Soil Testing；Therefore, it is its application of exploitation to research and develop matched various sensors
The precondition and guarantee of function.
Invention content
The technical problem to be solved by the invention is to provide one kind avoiding the occurrence of measurement blind area in common measurement range；
Reduce signal failure, enhancing apparatus measures ability, precision be high, wide adaptation range frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil
The sensor of characteristic.
The technical solution adopted in the present invention is：A kind of frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic of being suitable for
Sensor, including, the probe body and impedance transducer of at least three needles；The center needle of the probe body passes through the low electricity of macromolecule
The impedance transducer of the outer conductor of conductance material and reducing composition is connect with inner conductor copper core, remaining needle body and center
Needle body is parallel, is uniformly distributed in using center needle body as on the external circumference of a diameter of S in the center of circle, remaining needle body through impedance transducer with
The outer shield conductor of the coaxial cable connects；The coaxial cable other end connects frequency-domain frequency stepping system by BNC connector
Soil nmoisture content analyser.
The probe body material is STAINLESS STEEL WIRE.
The impedance transducer includes two tubular elements；
First component is hollow cylinder, and material is the substance of macromolecule low conductivity；The internal diameter d (mm) of first component
Equal with the outer diameter of sensor needle body, the outer diameter of first component is D (mm)；
Wherein Z is the impedance (ohm) that need to be converted, and ε is the relative dielectric constant of selected macromolecule material of low conductivity；
Second component includes the hollow Stainless Steel Shell of two reducings, and the shell of major diameter coats the outer diameter of first component,
And diameter and the outer diameter of first component are all mutually D (mm), in the concentric shell for being provided with minor diameter in the top of the shell of major diameter
The diameter of the housing of body, minor diameter is identical as the outer diameter of coaxial cable outer shield conductor.
The method for making the sensor for being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic, including following step
Suddenly,
A. main center's needle is STAINLESS STEEL WIRE, and a diameter of 3~8mm, center needle length is that impedance transducer length adds spy
Needle length, wherein the minimum 10~40cm of probe length；
B. along center needle body one end center, diameter 1.2mm, length L are drilled through2Endoporus, so as to copper core in coaxial cable
After insertion, it is fastenedly connected in a manner of cold pressing；
C. the outer lead body of a n needle sensor is n-1 roots STAINLESS STEEL WIRE identical with center needle body, after 90 ° of bending
It is D to be welded on outer diameter, and length is the stainless steel tube bottom of L0, and each stitch is evenly distributed on the external circumference of shielding needle of a diameter of S
On；
D. coaxial cable is first stripped out into L2The copper core of length is inserted into center needle body, cold pressing fastening；
E. coaxial cable is peelled off into L again1The crust of length exposes external shielding layer；
F. center needle body is inserted into impedance transducer, the stainless steel component minor diameter in impedance transducer and outer lead body
Fastening is cold-pressed at joint steel pipe.
The material outer diameter D and length L0 of first component-macromolecule low conductivity in impedance transducer are adjusted, realizes sensing
The impedance matching that device measures.
The beneficial effects of the invention are as follows：Impedance transducer can reasonably adjust the input impedance of probe, and center needle body is logical
The impedance transducer for crossing the outer conductor composition of macromolecule low conductivity material and reducing is connect with inner conductor copper core, outside
Lead body is connect through impedance transducer with the outer shield conductor of above-mentioned coaxial cable.By the outer diameter and length that adjust impedance transducer
Degree, the input resistant matching of the characteristic impedance and measuring instrument that make impedance transducer is best, avoids occurring in normality region blind
Point reduces signal decaying, meets the measurement demand under different condition.
In addition, according to different measurements and accuracy requirement, determines suitable impedance transducer length, overcome adjacent excessively close
The defect that is difficult to differentiate between of reflection, ensure that higher measurement accuracy；On the other hand, the excessive of impedance transducer is also avoided to add
The defect that the volume of sensor increases caused by long.
Description of the drawings
Fig. 1 is the schematic diagram of existing TDR soil testings system；
Fig. 2 be in existing TDR sensor to the simulation schematic diagram of coaxial cable；
Fig. 3 is sensor needle body sectional view in existing TDR；
Fig. 4 is that soil nmoisture content analyser measures sectional drawing；
Fig. 5 is impedance transducer structural schematic diagram of the present invention；
Fig. 6 is main body probe structure schematic diagram；
Fig. 7 is inventive sensor schematic diagram；
Fig. 8 a and Fig. 8 b are the outer lead body structural upright schematic diagram of four pin types and vertical view；
Fig. 9 is four needle sensor structural schematic diagrams；
Figure 10 is that 50 Ω probes of three-hand type measure 33% moisture soil sectional drawing；
Figure 11 is that 20 Ω probes of three-hand type measure 33% moisture soil sectional drawing；
Figure 12 a and Figure 12 b are the practical measurements of same soil sample different length impedance transducer；
Figure 13 is 25% measurement of water ratio sectional drawing of 3.5cm impedance transducers；
Figure 14 is 25% measurement of water ratio sectional drawing of 1.8cm impedance transducers；
Figure 15 is 25% measurement of water ratio sectional drawing of 12cm impedance transducers.
In figure：
1. 2. second component of first component, 3. needle body.
Specific implementation mode
Invention is further described in detail with reference to the accompanying drawings and detailed description：
As shown in Figures 5 to 9, a kind of sensing being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic of the present invention
Device, including, the probe body and impedance transducer of at least three needles；The probe body material is STAINLESS STEEL WIRE, probe body
The impedance transducer that is made up of the outer conductor of macromolecule low conductivity material and reducing of center needle and inner conductor
Copper core connects, remaining needle body is parallel with center needle body, is uniformly distributed in using center needle body as the circumscribed circle of the certain radius in the center of circle
Zhou Shang, remaining needle body are connect through impedance transducer with the outer shield conductor of the coaxial cable；The coaxial cable other end passes through BNC
Connector connects the professional soil nmoisture content analyser device of frequency-domain frequency stepping system, i.e. instrument disclosed in ZL2015103818577.
The impedance transducer length is L, including two tubular elements；
First component is hollow cylinder, and the side end that hollow cylinder is connect with second component is inwardly vertical to receive
Contracting, the material of first component are the substance of macromolecule low conductivity, such as polytetrafluoroethylene (PTFE)；The height of first component 1 is L0, internal diameter
D (mm) is equal with the outer diameter of sensor needle body 3, and the outer diameter of first component is D (mm), by coax impedance calculation formula(4) it obtains：
Wherein Z is the impedance (ohm) that need to be converted, and ε is the relative dielectric constant of selected macromolecule material of low conductivity；
Second component 2 includes the hollow Stainless Steel Shell of two reducings, and the cladding first component of shell 21 of major diameter is inside
The outer diameter of the outer diameter of vertical contraction, major diameter and first component is all mutually D (mm), is arranged concentrically above the shell of major diameter
There are the shell 22 of minor diameter, the diameter of the housing of minor diameter identical as the outer diameter of coaxial cable outer shield conductor.
Adjust the outer diameter D and length L of first component high molecular material in impedance transducer0, realize sensor measurement impedance
Best match, meet the measurement demand under different condition.
It is worth noting that ensure well to contact between each component.
The method for making the sensor for being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic, including following step
Suddenly：
A. center sensor needle body is STAINLESS STEEL WIRE, and according to requiring to determine, general diameter is 3~8mm, center needle length
Add probe length for impedance transducer length, wherein the minimum 10~40cm of probe length；
B. along center needle body one end center, diameter 1.2mm, length L are drilled through2Endoporus, so as to copper core in coaxial cable
After insertion, it is fastenedly connected in a manner of cold pressing；
C. the outer lead body of a n needle sensor is n-1 roots STAINLESS STEEL WIRE identical with center needle body, after 90 ° of bending
It is D, length L to be welded on outer diameter0Stainless steel tube bottom, each stitch is evenly distributed on the external circumference of shielding needle of a diameter of S
On；
D. coaxial cable is first stripped out into L2Long copper core is inserted into center needle body, cold pressing fastening；
E. coaxial cable is peelled off into L again1Long crust exposes external shielding layer；
F. center needle body is inserted into impedance transducer, the stainless steel component minor diameter in impedance transducer and outer lead body
Fastening is cold-pressed at joint steel pipe.
Embodiment
When the three-hand type probe that Figure 10 is 50 Ω of input impedance measures 33.74% moisture soil, hindered with input due to measuring impedance
It is anti-close, cause reflectance factor is too low to cause other signals noise jamming (first, left side peak is that coaxial cable BNC connector causes
Reflection), cause multiple peak values to occur, affect the accuracy of measurement.
Figure 11 is to measure same soil sample result sectional drawing when input impedance is adjusted to 20 Ω, it can be seen that measurement result is accurate
Really, but signal decaying is excessive.
Figure 12 a and Figure 12 b are for the moisture soil that volumetric water content is 10.87% (artificial drying method), different length impedance
The practical real-time snap shot measured of converter, Figure 12 a impedance transducer length are 3.5cm, and Figure 12 b impedance transducer length is
12cm。
Compare two sectional drawings it is found that when impedance transducer length is 12cm, three key reflections points of graphical display, respectively
To enter first formed when impedance transducer reflection, probe is inserted into second reflection formed at soil and probe end
The third of formation reflects, but when impedance transducer length is 3.5cm, and the first two pip has been fitted to a point, time
Between two pips, and amplitude is also the superposition of two reflectance factors, therefore its precision measured is affected.It is another
Aspect can accurately measure reflectance factor by lengthening impedance transducer length, therefore the other application of instrument is developed
There is important application value.
Due to structural strength, the probe that, need standing for portable instrument often plug in the wild, impedance
The length of converter should not be too short.And buried for fixed, for the relatively not high probe of intensity requirement, then it can suitably shorten resistance
Anti-rotation parallel operation length, so that measurement result is more accurate.
Figure 13~15 are that the probe measurement volumetric water content that impedance transducer length is respectively 3.5,1.8 and 12cm is
The measurement result of the moisture soil of 26.24% (oven drying method), it can be seen that both rear precision is higher than first.
For standard probe (impedance transducer length be 3.5cm), the artificial compensation of length in being calculated by formula
Probe length measures the precision of soil sample to improve.
Below for defect existing in the prior art, the example explanation that solves through the invention：
1, avoid measurement blind area occur in common measurement range
Fig. 4 is the practical measurement sectional drawing of soil nmoisture content analyser, and M1 (t1, m1), which is illustrated, to be generated after probe is inserted into soil
Reflection, M2 (t2, m2), which is then electromagnetic wave, to move ahead along probe and reaches the reflection of soil end generation, t1, t2 show respectively this two
The time (nanosecond) that a reflection occurs, and m1, m2 then show respectively their reflectance factor.
According to electromagnetic principles,
Wherein Z0It is the input impedance into sensor, the coax impedance for connecting instrument is 50 Ω.Z1Sensor from
The systematic survey impedance of body, dependent on the design of sensor itself and the dielectric constant of surveyed soil.
For the sensor of similar coaxial cable in structure, systematic survey impedance is：
Wherein ε r by survey soil relative dielectric constant, with apparent dielectric constant approximately equal.
When the input impedance of sensor and systematic survey impedance are close, according to ELECTROMAGNETIC REFLECTION principle, reflectance factor will drop
Low, the interference of other noise signals reduces so as to cause failure or accuracy is measured；It is with coaxial-type sensor outer barrel diameter
For 54mm, the interior a diameter of 4mm of needle：If directly being inputted by 50 Ω coaxial cables, can be obtained by (7) formula normal in opposite dielectric
When number ε r ≈ 9.75, systematic survey impedance Z1≈ 50, is theoretically analyzed at this time, and first pip of resolution chart disappears,
Failure is measured, we term it measure blind spot.By TOPP formula, volumetric soil water content at this time is about 18.36%, is in
The normality region of soil moisture content.
Therefore the input impedance that sensor is adjusted by impedance transducer, avoids blind spot occur in normality region being very must
It wants.
2, impedance matching is adjusted, signal failure is reduced, enhances the measurement capability range of instrument
Second pip M in Fig. 42It is that electromagnetic wave propagates the reflection for reaching and being generated behind end, but its amplitude m along sensor2
It is not the real reflectance factor of the reflection, but receives the " visual reflex that signal decaying and first pip masking influence
Coefficient ", true reflectance factor2M has relationship below with it：
Wherein α is the attenuation coefficient of sensor, is determined by the material of its structure and making, and l is that the needle body of insertion soil is long
Degree.By (8) if formula is as it can be seen that the excessive values that can also reduce " apparent reflection coefficient " m2 of m1, make measurement range be restricted.
From discussed above：Rationally the input impedance of adjustment probe is necessary.In the impedance transducer-of the present invention
The impedance transducer that heart needle body is made up of the outer conductor of macromolecule low conductivity material and reducing and inner conductor copper
Core connects, and outer lead body is connect through impedance transducer with the outer shield conductor of above-mentioned coaxial cable.By adjusting impedance transducer
Outer diameter and length, realize sensor measurement impedance best match, meet the measurement demand under different condition.
3, measurement accuracy
Time domain is without carrier frequency pulse regime, frequency-domain frequency used by frequency-domain frequency stepping system TDR instruments different from the past
The trace waveform that the TDR instrument tests interface of stepping system is presented is obtained after IDFT and a series of mathematical algorithm digital processings
It arrives, it has many advantages, such as that test result is simple and clear, readily identified；But also cause adjacent excessively close reflection to be difficult to differentiate between simultaneously,
The precision measured can thus be influenced.On the other hand, the lengthening of impedance transducer will also result in the volume increasing of sensor.Using this
Invention can determine suitable impedance transducer length according to different measurements and accuracy requirement.
4, further application and development
Under frequency-domain frequency stepping system, in the trace figure of test the amplitude of peak dot reflect the point reflect it is anti-
Coefficient is penetrated, has wide application and development foreground in Soil Testing, but when impedance transducer is shorter, neighboring reflection is folded
Add.By adjusting the impedance transducer length of the present invention, different reflections can be detached, further expand application range.
Since the soil nmoisture content analyser based on frequency-domain frequency stepping system is first Application in Soil Testing,
Although the sensor that traditional TDR instruments and other soil measuring Instruments use is more, not exclusively it is applicable in.At present
TDR technologies are in terms of agricultural, water conservancy and geotechnical engineering using increasingly extensive；Soil moisture based on frequency-domain frequency stepping system
Analyzer and used frequency-domain frequency stepping system and vector network reception technique, more traditional TDR technologies have more
It is widely applied foreground, it is the precondition and guarantee for developing its application function to research and develop matched various sensors.
Claims (5)
1. a kind of sensor being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic, it is characterised in that：Including at least
The probe body and impedance transducer of three needles；The center needle of the probe body passes through macromolecule low conductivity material and reducing
The impedance transducer of outer conductor composition is connect with inner conductor copper core, remaining needle body is parallel with center needle body, uniformly divides
It is distributed in using center needle body as on the external circumference of a diameter of S in the center of circle, remaining needle body is through impedance transducer and the coaxial cable
Outer shield conductor connects；The coaxial cable other end connects the soil nmoisture content analyser of frequency-domain frequency stepping system by BNC connector.
2. the sensor according to claim 1 for being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic, special
Sign is that the probe body material is STAINLESS STEEL WIRE.
3. the sensor according to claim 1 for being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic, special
Sign is that the impedance transducer includes two tubular elements；
First component is hollow cylinder, and material is the substance of macromolecule low conductivity；The internal diameter d (mm) of first component and biography
The outer diameter of sensor needle body is equal, and the outer diameter of first component is D (mm)；
Wherein Z is the impedance (ohm) that need to be converted, and ε is the relative dielectric constant of selected macromolecule material of low conductivity；
Second component includes the hollow Stainless Steel Shell of two reducings, and the shell of major diameter coats the outer diameter of first component, and straight
Diameter and the outer diameter of first component are all mutually D (mm), small in the concentric shell for being provided with minor diameter in the top of the shell of major diameter
The diameter of the housing of diameter is identical as the outer diameter of coaxial cable outer shield conductor.
4. making the side of the sensor described in claim 1 for being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic
Method, which is characterized in that include the following steps,
A. main center's needle is STAINLESS STEEL WIRE, and a diameter of 3~8mm, center needle length is that impedance transducer length adds probe long
Degree, wherein the minimum 10~40cm of probe length；
B. along center needle body one end center, diameter 1.2mm, length L are drilled through2Endoporus, so as in coaxial cable copper core be inserted into
Afterwards, it is fastenedly connected in a manner of cold pressing；
C. the outer lead body of a n needle sensor is n-1 roots STAINLESS STEEL WIRE identical with center needle body, is welded after 90 ° of bending
It is D in outer diameter, length is the stainless steel tube bottom of L0, and each stitch is evenly distributed on the external circumference of shielding needle of a diameter of S；
D. coaxial cable is first stripped out into L2The copper core of length is inserted into center needle body, cold pressing fastening；
E. coaxial cable is peelled off into L again1The crust of length exposes external shielding layer；
F. center needle body is inserted into impedance transducer, in the stainless steel component minor diameter of impedance transducer and the connection of outer lead body
Fastening is cold-pressed at steel pipe.
5. the making of the sensor according to claim 4 for being suitable for frequency-domain frequency stepping physiometry Dielectric Constant of NaCl Soil characteristic
Method, which is characterized in that adjust the material outer diameter D and length L of first component-macromolecule low conductivity in impedance transducer0,
Realize the impedance matching of sensor measurement.
Priority Applications (1)
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| CN113495090A (en) * | 2020-04-01 | 2021-10-12 | 天津特利普尔科技有限公司 | Conduit type annular structure sensor and method for measuring soil moisture |
| CN114199614A (en) * | 2021-11-01 | 2022-03-18 | 中铁第四勘察设计院集团有限公司 | Open type soil sampler |
| CN114199616A (en) * | 2021-11-01 | 2022-03-18 | 中铁第四勘察设计院集团有限公司 | Soil sampler |
| CN114199613A (en) * | 2021-11-01 | 2022-03-18 | 中铁第四勘察设计院集团有限公司 | Thin-wall soil sampler capable of measuring water content of soil sample |
| CN114199615A (en) * | 2021-11-01 | 2022-03-18 | 中铁第四勘察设计院集团有限公司 | Piston type soil sampler |
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