Abstract: A method of measuring properties of a moving cellulose, paper or board sheet. A first parameter of a first resonance caused by the moving sheet in a frequency range 1 GHz to 25 GHz of electromagnetic radiation is measured. A second parameter of an electromagnetic signal transmitted between at least a pair of transceiver parts of a transceiver sensor located on opposite sides of the moving sheet through the moving sheet is measured in a frequency range 25 GHz to 1000 GHz. A minimum difference between the frequency ranges related to the first parameter and the second parameter being at least 5 GHz. Both the dry stuff content and the weight of water per unit of area are determined on the basis of the first parameter, the second parameter and available information related to a distance travelled by the electromagnetic signal.

Abstract: An apparatus for measuring a surface comprises first sensors, which are distributed two-dimensionally in space, said first sensors interacting with the surface in a contactless manner using a microwave range of electromagnetic signals, and the first sensors receive at least two of the microwave signals of the interaction with information relating to distances between the sensors and the surface as a reflection, the microwave signals of the interaction representing both dimensions of the space of two-dimensional distribution of the first sensors. A data processing unit receives said information on the distances, and determines at least one geometrical parameter of the surface on the basis of the information.

Abstract: A method of measuring properties of a moving cellulose, paper or board sheet. A first parameter of a first resonance caused by the moving sheet in a frequency range 1 GHz to 25 GHz of electromagnetic radiation is measured. A second parameter of an electromagnetic signal transmitted between at least a pair of transceiver parts of a transceiver sensor located on opposite sides of the moving sheet through the moving sheet is measured in a frequency range 25 GHz to 1000 GHz. A minimum difference between the frequency ranges related to the first parameter and the second parameter being at least 5 GHz. Both the dry stuff content and the weight of water per unit of area are determined on the basis of the first parameter, the second parameter and available information related to a distance travelled by the electromagnetic signal.

Abstract: An apparatus for measuring flowable substance which has at least three microwave sensor elements arranged at separate locations in a measurement chamber in contact with the flowable substance. The sensor elements operate as at least two transmitter-receiver pairs, which transmit and receive microwave radiation via at last two paths of different lengths, through layers of dirt on the sensor elements and the flowable substance for eliminating an effect of dirt layers on the sensor elements from the measurement result. A signal processing unit has a controller which is configured to control feed of at least one substance which has an effect on the measured value of the flowable substance to the chamber on the basis of the measured value of the desired property of the flowable substance.

Abstract: An apparatus for measuring flowable substance which has at least three microwave sensor elements arranged at separate locations in a measurement chamber in contact with the flowable substance. The sensor elements operate as at least two transmitter-receiver pairs, which transmit and receive microwave radiation via at last two paths of different lengths, through layers of dirt on the sensor elements and the flowable substance for eliminating an effect of dirt layers on the sensor elements from the measurement result. A signal processing unit has a controller which is configured to control feed of at least one substance which has an effect on the measured value of the flowable substance to the chamber on the basis of the measured value of the desired property of the flowable substance.

Abstract: A sensor measures a sample in a measuring cell including a helix conductor. The shell structure of the measuring cell is made of an electrically non-conductive material. The measuring cell and at least part of the helix conductor are placeable inside a chamber. A radio-frequency signal input element couples a radio-frequency signal to the chamber to form a helix resonance. A radio-frequency signal output element is responsive to a helix resonance of the helix conductor and transmits a radio-frequency signal for measurement. A device for measuring a sample in a measuring cell includes the sensor, a radio-frequency signal source, and a measuring and control part. The radio-frequency signal source produces a radio-frequency signal to the input element. The measuring and control part measures a property of a sample on the basis of a resonance frequency.

Abstract: A sensor measures a sample in a measuring cell including a helix conductor. The shell structure of the measuring cell is made of an electrically non-conductive material. The measuring cell and at least part of the helix conductor are placeable inside a chamber. A radio-frequency signal input element couples a radio-frequency signal to the chamber to form a helix resonance. A radio-frequency signal output element is responsive to a helix resonance of the helix conductor and transmits a radio-frequency signal for measurement. A device for measuring a sample in a measuring cell includes the sensor, a radio-frequency signal source, and a measuring and control part. The radio-frequency signal source produces a radio-frequency signal to the input element. The measuring and control part measures a property of a sample on the basis of a resonance frequency.

Abstract: An electromagnetic field tuning and detection apparatus generates in to a material space and in at least two different directions radio frequency electromagnetic fields adapted to resonate in different directions at a different frequency on the basis of a material insertable into the material space; and a signal processing unit configured to determine a moisture content of the material on the basis of a resonance frequency of each electromagnetic field and quality of each resonance in different directions. While controlling a process, a control system comprises a measurement chamber and an electromagnetic field tuning and detection apparatus placed on each material feed line of the process. A controller may control the process on the basis of each determined moisture content on each feed line.

Abstract: An electromagnetic field tuning and detection apparatus generates in to a material space and in at least two different directions radio frequency electromagnetic fields adapted to resonate in different directions at a different frequency on the basis of a material insertable into the material space; and a signal processing unit configured to determine a moisture content of the material on the basis of a resonance frequency of each electromagnetic field and quality of each resonance in different directions. While controlling a process, a control system comprises a measurement chamber and an electromagnetic field tuning and detection apparatus placed on each material feed line of the process. A controller may control the process on the basis of each determined moisture content on each feed line.

Abstract: For measuring the water content of a web in the wire section of a paper machine, at least one radiofrequency-operated resonator sensor forms an electric near field, in which a web affects the resonance frequency of each resonator sensor. The water content of the web is measured as a function of the resonance frequency of each resonator sensor in a measuring unit.

Abstract: A generator generates radio-frequency electromagnetic radiation to a resonator whose resonance frequency is affected by a characteristic to be measured of an object to be measured. A receiver receives radio-frequency electromagnetic radiation from the resonator and a signal processing unit searches for a resonance frequency of the resonator for measuring the characteristic to be measured. The generator comprises a digital frequency synthesizer for scanning a frequency of radio-frequency electromagnetic radiation to be applied to the resonator over a desired frequency band by using discrete measuring frequencies.

Abstract: A method and an arrangement for testing a radio device without radiation losses are provided. The arrangement comprises a waveguide closed at both its ends and comprising a holder arranged to hold the radio device at least partly inside the waveguide in such a manner that the radiating part of the radio device remaining outside the waveguide is entirely inside the holder. The arrangement also comprises at least one coupling inside the waveguide for transmission and reception of a radio-frequency signal.

Abstract: A generator generates radio-frequency electromagnetic radiation to a resonator whose resonance frequency is affected by a characteristic to be measured of an object to be measured. A receiver receives radio-frequency electromagnetic radiation from the resonator and a signal processing unit searches for a resonance frequency of the resonator for measuring the characteristic to be measured. The generator comprises a digital frequency synthesizer for scanning a frequency of radio-frequency electromagnetic radiation to be applied to the resonator over a desired frequency band by using discrete measuring frequencies.

Abstract: An object to be measured is measured using microwave radiation. Oscillation energy is generated by means of a feedback coupled active unit. The solution involves generating resonance into at least one oscillator, each oscillator comprising at least one open resonator, each resonator being coupled to at least one active unit, by using the object to be measured as a functional part of the resonator, the object to be measured causing a resonance frequency dependent on the location of a surface of the object to be measured to be generated in each oscillator. A measurement part determines at least one characteristic of the object to be measured on the basis of the resonance frequency of each oscillator.

Abstract: For measuring the water content of a web in the wire section of a paper machine, at least one radiofrequency-operated resonator sensor forms an electric near field, in which a web affects the resonance frequency of each resonator sensor. The water content of the web is measured as a function of the resonance frequency of each resonator sensor in a measuring unit.

Abstract: An object to be measured is measured using microwave radiation. Oscillation energy is generated by means of a feedback coupled active unit. The solution involves generating resonance into at least one oscillator, each oscillator comprising at least one open resonator, each resonator being coupled to at least one active unit, by using the object to be measured as a functional part of the resonator, the object to be measured causing a resonance frequency dependent on the location of a surface of the object to be measured to be generated in each oscillator. A measurement part determines at least one characteristic of the object to be measured on the basis of the resonance frequency of each oscillator.

Abstract: A method and an arrangement for testing a radio device without radiation losses are provided. The arrangement comprises a waveguide closed at both its ends and comprising a holder arranged to hold the radio device at least partly inside the waveguide in such a manner that the radiating part of the radio device remaining outside the waveguide is entirely inside the holder. The arrangement also comprises at least one coupling inside the waveguide for transmission and reception of a radio-frequency signal.

Abstract: The invention relates to a method and an arrangement for measuring a fluid. Electromagnetic radiation is used to measure the consistency, flow and/or gas content of a fluid flowing in a process pipe (102). At least two of the measurements are carried out substantially from the same measurement point in the fluid in a measuring tube (202) by utilizing one integrated measuring equipment (200) comprising transmitters and receivers for electromagnetic radiation in order to carry out the aforementioned at least two measurements.

Abstract: The invention relates to a method and a measuring arrangement for measuring the gas content of a fluid (13). The fluid (13) comprises gas bubbles. In the method, microwave radiation (20) is transmitted through the fluid (13) and a signal (7) indicating the travel time, phase or amplitude of the radiation (20) is formed in a microwave measuring device (16), and a gas measuring equipment (18) determines the gas content of the fluid (13) by means of the signal (7).

Abstract: The invention relates to a method and an arrangement for measuring a fluid. Electromagnetic radiation is used to measure the consistency, flow and/or gas content of a fluid flowing in a process pipe (102). At least two of the measurements are carried out substantially from the same measurement point in the fluid in a measuring tube (202) by utilizing one integrated measuring equipment (200) comprising transmitters and receivers for electromagnetic radiation in order to carry out the aforementioned at least two measurements.