WO2000028615A1 - Dielectric waveguide microwave sensor - Google Patents

Dielectric waveguide microwave sensor Download PDF

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Publication number
WO2000028615A1
WO2000028615A1 PCT/SE1999/002054 SE9902054W WO0028615A1 WO 2000028615 A1 WO2000028615 A1 WO 2000028615A1 SE 9902054 W SE9902054 W SE 9902054W WO 0028615 A1 WO0028615 A1 WO 0028615A1
Authority
WO
WIPO (PCT)
Prior art keywords
dielectric
waveguide
piece
resonator
microwave sensor
Prior art date
Application number
PCT/SE1999/002054
Other languages
French (fr)
Inventor
Per-Simon Kildal
Original Assignee
Kildal Antenn Consulting Ab
Karlström, Anders
GRUNDSTRÖM, Görgen
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kildal Antenn Consulting Ab, Karlström, Anders, GRUNDSTRÖM, Görgen filed Critical Kildal Antenn Consulting Ab
Priority to AU17012/00A priority Critical patent/AU1701200A/en
Publication of WO2000028615A1 publication Critical patent/WO2000028615A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more

Definitions

  • the invention solves problems in connection with the measuring of concentration, density, thickness or small distances by means of a dielectric waveguide resonator for the microwave range, which is accomplished as a piece of dielectric waveguide or a piece of dielectri- cally filled metal waveguide.
  • the resonator is arranged close to the material to be measured and is affected by this material through a dielectric contact surface (interface) .
  • this contact surface is either an elongate opening in a metal wall, or one of the walls of the metal waveguide can be removed to form the surface.
  • the dielectric resonator can also be made of a piece of dielectric waveguide without any metal casing or cover.
  • the interface consists of all the parts of the dielectric walls that interacts with the material to be measured.
  • the dielectric material (or an artificial dielectric material) of a waveguide makes the propagation constant in the waveguide greater than that of the material to be measured.
  • the fields in the material region will be evanescent and there will be no radiation at all or little radiation into the material region. Nevertheless, the electromagnetic properties of the material, such as permittivity, permeability and losses, will affect the resonator.
  • a microwave resonator is characterised by the frequency and bandwidth of the resonance.
  • the ratio of resonance frequency to bandwidth is commonly referred to as the quality factor or Q-factor of the resonator.
  • the resonance frequency and the Q- factor can be measured accurately by measuring the transmission between two probes which are weakly connected to the resonator and arranged on opposite sides thereof. There is very little connection, or no connection at all, between the probes except at and in the vicinity of the resonance frequency.
  • the resonance frequency and the Q-factor can be determined directly from a measurement of the transmission between the probes as a function of the frequency.
  • the resonance frequency is the frequency at which the transmission has a maximum
  • the bandwidth is the difference in frequency between the two points on the transmission response where the transmission is 3 dB below its maximum.
  • a single microwave resonator can be constructed for several resonances, which permits measuring of a plurality of different resonance frequencies and corresponding Q- factors .
  • the resonance frequency and Q-factor of the dielectric waveguide resonator are dependent on its geometry and the electromagnetic properties of its filling material, as well as the electromagnetic properties of the external material.
  • a waveguide resonator has a cross- section which can support certain waveguide modes, which are reflected totally at both ends of the resonator. Resonance occurs for one of the modes when the length of the resonator corresponds to an integer number of half mode wavelengths in the waveguide.
  • the Q-factor is a measure of the loss in the resonator; the smaller losses the higher Q-factor.
  • a waveguide resonator can be constructed for a plurality of resonance frequencies in a certain frequency band by using a plurality of waveguide modes, or a plurality of resonances of the same mode occurring at different numbers of mode wavelengths in the waveguide.
  • the advantage of this invention compared with other microwave sensors is that the material to be tested need not be located inside the actual resonator and that the resonator can easily be integrated with the wall of a tube, box or the like containing the material.
  • the dielectric waveguide resonator is sensitive to all materials located within the region of evanescent reactive fields outside the physical resonator itself. The optimal extent of this region depends on the application and can be selected by the correctly selected frequency, dimensions and material for the resonator.
  • a cellulose fibre refiner Such refiners contain two large and heavy steel plates which are rotated relative to one another and grain pieces of wood to fibres. The gap between the plates is but a fraction of a millimetre. It is vital to control the distance between the plates, the plate spacing, and the quantity of water in the suspension to obtain the correct quality of the papermaking pulp and to prolong the life of the steel plates which are formed with a pattern of grooves having a width of a few millimetres.
  • a dielectric microwave resonator according to the invention can be placed inside one of these grooves and measure the fibre concentration, the quantity of water and the distance between the plates.
  • a plurality of resonators can be arranged in different positions in the steel plates to measure concentration, quantity of water and distance as a function of the radius from the axis of rotation of the steel plates.
  • Figs 1, 2 and 3 illustrate three examples of a dielectric waveguide resonator which is rectangular in cross-section.
  • Figs 4 and 5 illustrate two examples of a dielectric waveguide resonator which is circular in cross-section.
  • Fig. 6 illustrates a dielectric waveguide resonator enclosed in a metal plate.
  • Fig. 7 illustrates a dielectric waveguide resonator embedded in a groove in a metal plate.
  • Fig. 8 is a cross-sectional view of a dielectric waveguide resonator embedded in a metal plate.
  • Fig. 9 is a cross-sectional view of a dielectric waveguide resonator embedded in a metal plate and another metal plate is arranged so as to form a narrow space or gap between the two plates .
  • Figs 10 and 11 are cross-sectional views of a dielectric waveguide resonator of circular cross-section. The cross-sections are taken through one of the coaxial lines.
  • Figs 12, 13 and 14 are cross-sectional views of dielectric resonators of rectangular cross-section. The cross-sections are taken through one of the coaxial lines .
  • Figs 1-7 show different dielectric waveguide resonators.
  • the versions in Figs 1-3 are made of waveguides which are rectangular in cross- section 1, and the ver- sions in Figs 4 and 5 use waveguides which are circular in cross-section 1.
  • the cross-sections can also have other forms.
  • the version in Fig. 1 has a metal coating on all walls, except the upper wall 2. This wall forms the interface 2 with the region or material to be measur- ed.
  • the version in Fig. 3 has no metal coating, so that all walls form the interface with the material or region to be measured.
  • the dielectric resonator in Fig. 4 is coated with metal and has a longitudinal opening slot in the wall which represents the interface 2, and the version in Fig.
  • All dielectric waveguide resonators in Figs 1-5 have two coaxial lines connected thereto. These lines can be coaxial cables, semirigid coaxial lines or rigid tubes with a centre conductor. One of the ends of both coaxial lines is connected to opposite ends of the waveguide resonator. They are connected to the dielectric resonator in such manner that the electromagnetic connection is weak. This connection can be made as shown in Figs 10, 11, 12, 13 and 14.
  • Figs 8-9 show how two resonators which are rectangular in cross-section can be embedded in a metal plate 5 and a metal plate 5 with a groove 6 in such manner that the interface 2 is positioned In the same plane as the surface of the metal plate.
  • Figs 8 and 9 show an example of how the dielectric resonator can be mounted in the plate.
  • the version in Fig. 9 also shows one more metal plate 7 arranged in such manner that a space 8 forms between the plates.
  • the cross-sections in Figs 7 and 8 are taken through one of the coaxial lines .
  • the two plates can be rotated relative to one another in the same way as in a refiner.
  • Figs 10 and 11 are cross-sectional views of dielectric resonators of circular cross-section and one of its coaxial lines.
  • the coaxial line has an outer conductor 9 and a centre conductor 10.
  • the connection to the resonator is made in Fig. 10 by fixing the coaxial line in a circular hole in the resonator and in Fig. 11 by fixing the centre conductor in a hole in the resonator.
  • the coaxial line can also be fixed directly to the surface of the resonator.
  • Figs 12-14 illustrate various techniques of con- necting the coaxial line to resonators of rectangular cross- section.
  • the point where the coaxial line is connected is located in different positions in Figs 12- 14. This position can be used to select the single mode or those modes in the resonator that is/are to be used.
  • the centre conductor 10 and the outer conductor 9 can penetrate into the resonator or not. Under all circumstances there must not be a metal contact between the centre conductor 10 and a metal wall in the resonator close to the outer conductor 9 of the cable.
  • the coaxial line can also alternatively be connected to the two end walls of the waveguide resonator. Operational Principle
  • the dielectric waveguide has a limited length and forms a cavity for the electromagnetic fields. This cavity is resonant to different waveguide modes which can propagate in the waveguide. The resonant field will also extend outside the resonator via the interface. See also the paragraph regarding the main features .

Abstract

The invention discloses a piece of a dielectric waveguide or dielectrically filled metal waveguide which is used as microwave resonator in a sensor system to determine the properties of the material and the dimensions of the space surrounding the resonator. The resonator generates evanescent fields in this material and a space through a dielectric interface (2). The properties of the material and the dimensions of the space are determined indirectly by measuring frequency and band width of the transmission response of the resonator.

Description

DIELECTRIC WAVEGUIDE MICROWAVE SENSOR
Background of the Invention
Many industrial processes can be better controlled if the concentration, density or thickness of the materials used in the process can be measured accurately. In the same way there may be a need for measuring the distance between plates that are used in the process. The improved control of the process that is achieved by such measurements results in a more stable quality of the final product and a longer life-time of the production equipment. As examples of the above, mention can be made of measuring of the quantity of water in porous materials such as tobacco, tea and powder, and measuring of the concentration of cellulose fibres in water, vapour or moist when pieces of wood are beaten in a cellulose fibre refiner. The invention discloses a microwave sensor for measuring concentration, density, thickness or small distances .
Objects and Main Features of the Invention The invention solves problems in connection with the measuring of concentration, density, thickness or small distances by means of a dielectric waveguide resonator for the microwave range, which is accomplished as a piece of dielectric waveguide or a piece of dielectri- cally filled metal waveguide. The resonator is arranged close to the material to be measured and is affected by this material through a dielectric contact surface (interface) . When the dielectric resonator is constructed as a piece of dielectrically filled metal waveguide, this contact surface is either an elongate opening in a metal wall, or one of the walls of the metal waveguide can be removed to form the surface. The dielectric resonator can also be made of a piece of dielectric waveguide without any metal casing or cover. In this case, the interface consists of all the parts of the dielectric walls that interacts with the material to be measured. The dielectric material (or an artificial dielectric material) of a waveguide makes the propagation constant in the waveguide greater than that of the material to be measured. As a result, the fields in the material region will be evanescent and there will be no radiation at all or little radiation into the material region. Nevertheless, the electromagnetic properties of the material, such as permittivity, permeability and losses, will affect the resonator.
A microwave resonator is characterised by the frequency and bandwidth of the resonance. The ratio of resonance frequency to bandwidth is commonly referred to as the quality factor or Q-factor of the resonator. The resonance frequency and the Q- factor can be measured accurately by measuring the transmission between two probes which are weakly connected to the resonator and arranged on opposite sides thereof. There is very little connection, or no connection at all, between the probes except at and in the vicinity of the resonance frequency. The resonance frequency and the Q-factor can be determined directly from a measurement of the transmission between the probes as a function of the frequency. The resonance frequency is the frequency at which the transmission has a maximum, and the bandwidth is the difference in frequency between the two points on the transmission response where the transmission is 3 dB below its maximum. Such measurements can be carried out easily and accurately with a network analyser. It is also possible to produce equipment for measuring resonance frequency and bandwidth in some other manner. A single microwave resonator can be constructed for several resonances, which permits measuring of a plurality of different resonance frequencies and corresponding Q- factors . The resonance frequency and Q-factor of the dielectric waveguide resonator are dependent on its geometry and the electromagnetic properties of its filling material, as well as the electromagnetic properties of the external material. A waveguide resonator has a cross- section which can support certain waveguide modes, which are reflected totally at both ends of the resonator. Resonance occurs for one of the modes when the length of the resonator corresponds to an integer number of half mode wavelengths in the waveguide. The Q-factor is a measure of the loss in the resonator; the smaller losses the higher Q-factor. A waveguide resonator can be constructed for a plurality of resonance frequencies in a certain frequency band by using a plurality of waveguide modes, or a plurality of resonances of the same mode occurring at different numbers of mode wavelengths in the waveguide. When the external evanescent fields in the slotted dielectric waveguide resonator described in the invention cooperate with a material, the resonance frequency and the Q-factor change, and the change depends on the propagation constant and the loss in the material as well as the dimensions of the material. These dependence relations are known from the numerical studies of the dielectric waveguide resonator when arranged in different materials with known propagation constants, losses and dimensions. Therefore the values of the measured materials will be found by comparing the measurements with such simulated results. These results depend on the density or concentration of the material which can thus be determined indirectly by calibration of the propagation constants and losses relative to empirical or in some other way determined relations to density or concentration.
The advantage of this invention compared with other microwave sensors is that the material to be tested need not be located inside the actual resonator and that the resonator can easily be integrated with the wall of a tube, box or the like containing the material. The dielectric waveguide resonator is sensitive to all materials located within the region of evanescent reactive fields outside the physical resonator itself. The optimal extent of this region depends on the application and can be selected by the correctly selected frequency, dimensions and material for the resonator.
One application of particular interest is a cellulose fibre refiner. Such refiners contain two large and heavy steel plates which are rotated relative to one another and grain pieces of wood to fibres. The gap between the plates is but a fraction of a millimetre. It is vital to control the distance between the plates, the plate spacing, and the quantity of water in the suspension to obtain the correct quality of the papermaking pulp and to prolong the life of the steel plates which are formed with a pattern of grooves having a width of a few millimetres. A dielectric microwave resonator according to the invention can be placed inside one of these grooves and measure the fibre concentration, the quantity of water and the distance between the plates. A plurality of resonators can be arranged in different positions in the steel plates to measure concentration, quantity of water and distance as a function of the radius from the axis of rotation of the steel plates.
Description of the Drawings
Figs 1, 2 and 3 illustrate three examples of a dielectric waveguide resonator which is rectangular in cross-section.
Figs 4 and 5 illustrate two examples of a dielectric waveguide resonator which is circular in cross-section.
Fig. 6 illustrates a dielectric waveguide resonator enclosed in a metal plate.
Fig. 7 illustrates a dielectric waveguide resonator embedded in a groove in a metal plate. Fig. 8 is a cross-sectional view of a dielectric waveguide resonator embedded in a metal plate.
Fig. 9 is a cross-sectional view of a dielectric waveguide resonator embedded in a metal plate and another metal plate is arranged so as to form a narrow space or gap between the two plates .
Figs 10 and 11 are cross-sectional views of a dielectric waveguide resonator of circular cross-section. The cross-sections are taken through one of the coaxial lines.
Figs 12, 13 and 14 are cross-sectional views of dielectric resonators of rectangular cross-section. The cross-sections are taken through one of the coaxial lines .
Description of Embodiments
Figs 1-7 show different dielectric waveguide resonators. The versions in Figs 1-3 are made of waveguides which are rectangular in cross- section 1, and the ver- sions in Figs 4 and 5 use waveguides which are circular in cross-section 1. The cross-sections can also have other forms. The version in Fig. 1 has a metal coating on all walls, except the upper wall 2. This wall forms the interface 2 with the region or material to be measur- ed. The version in Fig. 3 has no metal coating, so that all walls form the interface with the material or region to be measured. The dielectric resonator in Fig. 4 is coated with metal and has a longitudinal opening slot in the wall which represents the interface 2, and the version in Fig. 5 has no metal coating so that all walls represent the interface 2. All dielectric waveguide resonators in Figs 1-5 have two coaxial lines connected thereto. These lines can be coaxial cables, semirigid coaxial lines or rigid tubes with a centre conductor. One of the ends of both coaxial lines is connected to opposite ends of the waveguide resonator. They are connected to the dielectric resonator in such manner that the electromagnetic connection is weak. This connection can be made as shown in Figs 10, 11, 12, 13 and 14.
Figs 8-9 show how two resonators which are rectangular in cross-section can be embedded in a metal plate 5 and a metal plate 5 with a groove 6 in such manner that the interface 2 is positioned In the same plane as the surface of the metal plate. Figs 8 and 9 show an example of how the dielectric resonator can be mounted in the plate. The version in Fig. 9 also shows one more metal plate 7 arranged in such manner that a space 8 forms between the plates. The cross-sections in Figs 7 and 8 are taken through one of the coaxial lines . The two plates can be rotated relative to one another in the same way as in a refiner. Figs 10 and 11 are cross-sectional views of dielectric resonators of circular cross-section and one of its coaxial lines. The coaxial line has an outer conductor 9 and a centre conductor 10. The connection to the resonator is made in Fig. 10 by fixing the coaxial line in a circular hole in the resonator and in Fig. 11 by fixing the centre conductor in a hole in the resonator. The coaxial line can also be fixed directly to the surface of the resonator.
Figs 12-14 illustrate various techniques of con- necting the coaxial line to resonators of rectangular cross- section. The point where the coaxial line is connected is located in different positions in Figs 12- 14. This position can be used to select the single mode or those modes in the resonator that is/are to be used. The centre conductor 10 and the outer conductor 9 can penetrate into the resonator or not. Under all circumstances there must not be a metal contact between the centre conductor 10 and a metal wall in the resonator close to the outer conductor 9 of the cable. The coaxial line can also alternatively be connected to the two end walls of the waveguide resonator. Operational Principle
The dielectric waveguide has a limited length and forms a cavity for the electromagnetic fields. This cavity is resonant to different waveguide modes which can propagate in the waveguide. The resonant field will also extend outside the resonator via the interface. See also the paragraph regarding the main features .

Claims

1. A dielectric microwave sensor comprising a dielectric waveguide resonator formed as a piece of a dielectric waveguide, which is connected between the first ends of two coaxial lines (4) , of which the second ends are connected to a microwave instrument or a microwave circuit measuring the frequency response between said two ends of the coaxial lines (4) , and in which said frequency response is used to determine the properties of the material or the dimensions of the space, or both, surrounding the entire piece, or parts of the piece, of the dielectrically filled waveguide, c h a r a c t e r - i s e d in that at least part of the surface of the walls of the dielectric waveguide piece forms an interface (2) with said material or space surrounding the waveguide piece, and that the coaxial lines are connected electromagnetically weakly to the fields in the waveguide piece, evanescent fields, which are associated with the non-evanescent fields inside the dielectric waveguide piece, being present in and affected by the electromagnetic properties and dimensions of the material or the dimensions of the space surrounding the waveguide piece.
2. A dielectric microwave sensor as claimed in claim 1, c h a r a c t e r i s e d in that the dielectric waveguide piece has one or more metallic side walls, but at least part of the wall surfaces of the waveguide piece not comprising metallic side walls to form an interface (2) with the material or the space surrounding the waveguide piece.
3. A dielectric microwave sensor as claimed in claim 1 or 2 , c h a r a c t e r i s e d in that the dielectric waveguide piece has metallic side walls designed in such manner that the resonator also works as a dielectrically filled metal cavity or as a piece of a dielectrically filled metal waveguide, but at least part of the wall surfaces of the metal cavity not comprising metallic side walls to form an interface (2) with the material or the space surrounding the waveguide .
4. A dielectric microwave sensor as claimed in claim 1, c ha r a c t e r i s e d in that the dielectric waveguide piece does not comprise metallic side walls.
5. A dielectric microwave sensor as claimed in any one of the preceding claims, c h a r a c t e r i s e d in that the dielectric material of the waveguide consists of areas of different dielectric materials.
6. A dielectric microwave sensor as claimed in any one of the preceding claims, c h a r a c t e r i s e d in that the interface (2) comprises one or more transverse or longitudinal metal strips .
PCT/SE1999/002054 1998-11-11 1999-11-11 Dielectric waveguide microwave sensor WO2000028615A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU17012/00A AU1701200A (en) 1998-11-11 1999-11-11 Dielectric waveguide microwave sensor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9803850-8 1998-11-11
SE9803850A SE9803850L (en) 1998-11-11 1998-11-11 Dielectric microwave sensor

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003031958A2 (en) * 2001-10-12 2003-04-17 Wisconsin Alumni Research Foundation Microwave dielectric spectroscopy method and apparatus for assays of proteins and other biological molecules
EP1316630A1 (en) * 2001-11-28 2003-06-04 TEWS ELEKTRONIK Dipl.-Ing. Manfred Tews Device and process for measuring the mass and the humidity of fibrous material in a spinning preparation machine
US6837122B2 (en) 2001-11-28 2005-01-04 Tews Elektronik Device and method for detecting the mass and the moisture content for spinning preparation machines
EP2035814A1 (en) * 2006-06-22 2009-03-18 Senfit OY Measuring of water content
GB2455722A (en) * 2007-12-18 2009-06-24 Hong Siang Tan A spaced plate waveguide probe for dielectric measurement of biological tissue
EP2175261A3 (en) * 2006-09-29 2010-07-21 Forschungszentrum Jülich Gmbh Method for identifying a sample in a container, e.g. when conducting a traveller survey in the check-in area, by determining the resonance frequency and the quality of a dielectric resonator to which the container is arranged
WO2013164627A1 (en) * 2012-05-02 2013-11-07 Heriot-Watt University Microwave cavity sensor
DE102014109399A1 (en) * 2014-07-04 2016-01-07 Sick Ag Sensor for a roller conveyor and method for detecting objects located on a roller conveyor
DE102014109401A1 (en) * 2014-07-04 2016-01-07 Sick Ag Sensor for a roller conveyor and method for detecting objects located on a roller conveyor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4866370A (en) * 1988-01-22 1989-09-12 United Kingdom Atomic Energy Authority Material characterization
DE3929922A1 (en) * 1988-09-28 1990-03-29 Bauakademie Ddr Microwave probe for moisture content measurement - contains material of dielectric constant similar to material to be measured, to increase accuracy
US5156976A (en) * 1991-06-07 1992-10-20 Ciba Corning Diagnostics Corp. Evanescent wave sensor shell and apparatus
DE29711571U1 (en) * 1997-07-02 1998-11-05 Tews Elektronik Moisture and density sensor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4866370A (en) * 1988-01-22 1989-09-12 United Kingdom Atomic Energy Authority Material characterization
DE3929922A1 (en) * 1988-09-28 1990-03-29 Bauakademie Ddr Microwave probe for moisture content measurement - contains material of dielectric constant similar to material to be measured, to increase accuracy
US5156976A (en) * 1991-06-07 1992-10-20 Ciba Corning Diagnostics Corp. Evanescent wave sensor shell and apparatus
DE29711571U1 (en) * 1997-07-02 1998-11-05 Tews Elektronik Moisture and density sensor

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003031958A3 (en) * 2001-10-12 2003-10-16 Wisconsin Alumni Res Found Microwave dielectric spectroscopy method and apparatus for assays of proteins and other biological molecules
US6801029B2 (en) 2001-10-12 2004-10-05 Wisconsin Alumni Research Foundation Microwave dielectric spectroscopy method and apparatus
WO2003031958A2 (en) * 2001-10-12 2003-04-17 Wisconsin Alumni Research Foundation Microwave dielectric spectroscopy method and apparatus for assays of proteins and other biological molecules
EP1316630A1 (en) * 2001-11-28 2003-06-04 TEWS ELEKTRONIK Dipl.-Ing. Manfred Tews Device and process for measuring the mass and the humidity of fibrous material in a spinning preparation machine
US6837122B2 (en) 2001-11-28 2005-01-04 Tews Elektronik Device and method for detecting the mass and the moisture content for spinning preparation machines
EP2035814A4 (en) * 2006-06-22 2009-07-01 Senfit Oy Measuring of water content
EP2035814A1 (en) * 2006-06-22 2009-03-18 Senfit OY Measuring of water content
EP2175261A3 (en) * 2006-09-29 2010-07-21 Forschungszentrum Jülich Gmbh Method for identifying a sample in a container, e.g. when conducting a traveller survey in the check-in area, by determining the resonance frequency and the quality of a dielectric resonator to which the container is arranged
US8040132B2 (en) 2006-09-29 2011-10-18 Forschungszentrum Juelich Gmbh Method for identifying a sample in a container, e.g. when conducting a traveler survey in the check-in area, by determining the resonance frequency and the quality of a dielectric resonator to which the container is arranged
GB2455722A (en) * 2007-12-18 2009-06-24 Hong Siang Tan A spaced plate waveguide probe for dielectric measurement of biological tissue
WO2013164627A1 (en) * 2012-05-02 2013-11-07 Heriot-Watt University Microwave cavity sensor
CN104704351A (en) * 2012-05-02 2015-06-10 赫瑞-瓦特大学 Microwave cavity sensor
CN104704351B (en) * 2012-05-02 2018-07-10 赫瑞-瓦特大学 microwave cavity sensor
US10024806B2 (en) 2012-05-02 2018-07-17 Heriot-Watt University Microwave cavity sensor
DE102014109399A1 (en) * 2014-07-04 2016-01-07 Sick Ag Sensor for a roller conveyor and method for detecting objects located on a roller conveyor
DE102014109401A1 (en) * 2014-07-04 2016-01-07 Sick Ag Sensor for a roller conveyor and method for detecting objects located on a roller conveyor
DE102014109399B4 (en) * 2014-07-04 2017-03-16 Sick Ag Sensor for a roller conveyor and method for detecting objects located on a roller conveyor
DE102014109401B4 (en) * 2014-07-04 2017-04-06 Sick Ag Sensor for a roller conveyor and method for detecting objects located on a roller conveyor

Also Published As

Publication number Publication date
SE9803850L (en) 2000-05-12
AU1701200A (en) 2000-05-29
SE9803850D0 (en) 1998-11-11

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