Microwave Measurements with Active Systems

Ajmera, R. C.; Batchelor, D. B.; Lashinsky, H.

doi:10.1109/gmtt.1972.1122983

Cited by 3 publications

(3 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this application, the solution of the electromagnetic problem for this element, was solved with the aid of auxiliary vector potentials13. In (1) and (2) • cot(hd) = Erh tan (2) cot(hd) = cot[ where Er S the complex permittivity of the material and the values h and 1 represent the wavenumber of the material zone and the empty zone, respectively. The complex propagation constant in this fragment of waveguide is given by,…”

Section: Theoretical Modelmentioning

confidence: 99%

<title>Continuous monitoring of the progressive degradation of a liquid composite by means of a noninvasive microwave resonator</title>

2000

View full text Add to dashboard Cite

Microwave control capabilities have been used to monitor the degradation of poiyoi, an alcohol composite material commonly used in the footwear industry for polymerization purposes. The liquid flows continuously inside a thin pipe and its desirable properties are altered with time associated to moisture absorption processes. Consequently, variations in the dielectric properties are involved, and they can be detected by permittivity measurements. In this paper, in order to obtain high sensitivity and resolution, a rectangular cavity resonator working at a fixed frequency was designed using as sample holder a rectangular pipe containing the liquid going through. Changes in the liquid modify the original response of the cavity with a non-degraded liquid and these differences have been used to determine the degree of degradation of the material. The final response of the microwave resonator was experimentally validated with measurements in a continuous line.

show abstract

Section: Theoretical Modelmentioning

confidence: 99%

<title>Continuous monitoring of the progressive degradation of a liquid composite by means of a noninvasive microwave resonator</title>

2000

View full text Add to dashboard Cite

show abstract

“…More recently active transducers have been introduced for similar measurements employing either closed [4][5][6] or open [7][8][9] cavity resonators. This paper will describe the design of the Regenerative Digital Transducer and some results of measurements obtained in the food and paper industries.…”

Section: Introductionmentioning

confidence: 99%

“…INTRODUCTION Passive transducers have been used in the past for the measurement of non-electrical parameters such as moisture content and metal strip thickness [1-3]. More recently active transducers have been introduced for similar measurements employing either closed [4][5][6] or open [7-9] cavity resonators. This paper will describe the design of the Regenerative Digital Transducer and some results of measurements obtained in the food and paper industries.…”

mentioning

confidence: 99%

The Regenerative Digital Transducer (RDT): A New Active Microwave Field Sensor for Industrial Measurements and Control

Bosisio

Nappert

Quoc

1974

4th European Microwave Conference, 1974

View full text Add to dashboard Cite

A regenerative digital transducer (RDT) with an active linear response is described. The RDT can be operated in a contact or non-contact mode for moisture measurements in dielectric webs and in liquids or oils flowing inside dielectric pipes. The design is adapted for industrial measurements and on-line control purposes. INTRODUCTION Passive transducers have been used in the past for the measurement of non-electrical parameters such as moisture content and metal strip thickness [1-3]. More recently active transducers have been introduced for similar measurements employing either closed [4][5][6] or open [7-9] cavity resonators. This paper will describe the design of the Regenerative Digital Transducer and some results of measurements obtained in the food and paper industries. The RDT uses a transmission type, low frequency (less than 500 MHz) far field resonator in an external feedback loop of a transistor amplifier such that direct frequency measurements with inexpensive and accurate counters are possible. Figure 1 shows a typical block diagram of the RUT in use with four measuring systems. In system 1 the frequency is read directly from a counter and the observation is manually recorded. This is the simplest and most inexpensive ar-PROCESS PROCESS rangement. In system 2 the coun-

show abstract

Microwave measurements with active systems

et al. 1974

View full text Add to dashboard Cite

Possible practical applications of a novel technique for the measurement of dielectric constant, or analogous quantities, at microwave frequencies are considered. Although originally developed for microwave diagnostics in plasma-physics research, it is felt that the method may be of interest in certain problems of current scientific and technological interest.Conventional systems for the determination of microwave dielectric constant are "passive" in the sense that the quantities of interest are determined from a shift in phase, or frequency, in a passive element, such as a microwave bridge; the microwave energy required for the measurement is derived from an external source.In the method described here, use is made of an "activep9 system in which a positive feedback loop containing a microwave ampiifier provides positive gain. The entire configuration, including the measurement element, then comprises a microwave oscillator, the frequency and amplitude of the oscillator containing information on the quantities being measured. It appears that the method can be attractive from the point of view of sensitivity, response time, linearity, dynamic range, and convenience of readout. In addition, an active system can function as its own telemetry unit.Aspects of the theorfof active systems are analyzed, and factors that enter into the design and construction of such systems are described. Experiments carried out to evaluate active systems in gas turbulence measurements and in the determination of size distributions of particles with dimensions of tens of microns are described.

show abstract

Microwave Measurements with Active Systems

Cited by 3 publications

References 7 publications

<title>Continuous monitoring of the progressive degradation of a liquid composite by means of a noninvasive microwave resonator</title>

<title>Continuous monitoring of the progressive degradation of a liquid composite by means of a noninvasive microwave resonator</title>

The Regenerative Digital Transducer (RDT): A New Active Microwave Field Sensor for Industrial Measurements and Control

Microwave measurements with active systems

Contact Info

Product

Resources

About