Quadrature method for broadband measurement of microwave path parameters

A mathematical model has been developed for the procedure for broadband automatic measurement of the complex reflection coefficient and power level in the microwave path based on the quadrature measurement method. Analytical expressions are obtained for the quadrature components at the outputs of a quadrature demodulator connected with a switch to two non-directional measuring probes for the case of an unmatched microwave path. A modified system of nonlinear equations with respect to measured values was formed and solved, which allows setting zero assumptions. A block diagram of a broadband device for built-in automatic control of microwave channel parameters has been developed, which implements the developed measurement procedure and the solution of a system of measurement equations to determine the current values of the power level factor, as well as the modulus and argument of the complex reflection coefficient.

ДОСЛІДЖЕННЯ ВІДБИТТЯ УЛЬТРАЗВУКОВИХ ХВИЛЬ ВІД ОДНОШАРОВИХ ТЕКСТИЛЬНИХ ПОЛОТЕН ТА ДВОШАРОВИХ ТЕКСТИЛЬНИХ ПАКЕТІВ ІЗ РІЗНИМ РОЗМІРОМ ПОР

Investigate the influence of single-layer textile fabrics and two-layer textile bags on the parameters of ultrasonic waves that interact with them. In particular, to investigate the dependence of the complex reflection coefficient of ultrasonic waves on the total thickness and basis weight of textile material. Methodology. The analytical part of the study consisted in obtaining an expression for the complex reflection coefficient of ultrasonic waves and in modeling its dependence on the thickness and basis weight of different textile materials. The proposed method of control of these technological parameters consists in irradiation of textile materials with ultrasonic waves with the subsequent reception of the waves reflected from textile material, their digitization and carrying out the computer analysis of the received results. Findings. Analytical expressions are obtained that relate the thickness and basis weight of single-layer canvases, two-layer textile bags with a complex spatial structure, on the one hand, and the reflection coefficient of ultrasonic waves from such materials, on the other hand. Analytical calculations were made and mathematical modeling was performed based on the results of theoretical research. Originality. As a result of theoretical studies, it is determined how the thickness and properties of each of the two layers of porous textile materials affect the reflection of ultrasonic waves. This makes it possible on the basis of ultrasonic measurements to determine both the total thickness of textile materials and their basis weight with the accuracy required for their production. Practical value. The obtained analytical dependences are another step towards the creation of control and measuring equipment to determine the properties of single-layer textile fabrics and two-layer porous textile bags. This will help determine the overall thickness and basis weight of materials with a complex spatial structure.

ВІДБИТТЯ УЛЬТРАЗВУКОВИХ ХВИЛЬ ВІД ДВОШАРОВОГО ПАКЕТУ ТЕКСТИЛЬНИХ МАТЕРІАЛІВ ЗІ ЩІЛЬНИМ ВЕРХНІМ ШАРОМ

Obtain and show in general terms the expression for the module of the complex reflection coefficient of ultrasonic waves from a two-layer package of textile materials with a dense first layer. The above is necessary for the possibility of research of contactless control of such materials. To analyze the process of reflection of waves from a controlled material, the method of superposition of sounding vibrations is used. In general terms, the expression for the complex reflection coefficient of ultrasonic waves from a two-layer package of textile materials with a dense first layer is shown. It is proved that taking into account the complete attenuation of the reflected waves in the layer of the first material, it is possible to simplify the basic expressions for the complex reflection coefficient from a package of textile materials. It is shown that the change in the amplitude of the reflected ultrasonic waves for the material presented in the work with a change in the thickness of its layers is very small. The change in the amplitude of the reflected waves for such materials mainly causes a dense first layer of package of textile materials. The dependences of the real and imaginary parts of the complex reflection coefficient of ultrasonic waves on a package of textile materials with a dense first layer are obtained, which will help analytically determine both the change in the amplitude of the waves and their phase shift caused by the interaction of these vibrations with the material. It is proposed to use the component expressions for the module of the complex reflection coefficient of ultrasonic waves, which will allow you to adjust the parameters of the contactless transducers for different two-layer package of textile materials with a dense surface layer. To ensure the possibility of determining a small change in the measured magnitude of the amplitude of the reflected ultrasonic waves from the two-layer package of textile materials with the first dense layer, you can use switching and modulation devices and transducers. This will eliminate the errors that may be associated with the non-identity of the measuring channels when determining a small change in the amplitude of the reflected ultrasonic waves.

Validation of a Broadband Tissue-Equivalent Liquid for SAR Measurement and Monitoring of Its Dielectric Properties for Use in a Sealed Phantom

We report on the development of a method for measuring the permittivity and conductivity of fluids inside a sealed tank (or a pipe) by using an embedded coaxial probe. Permittivity and conductivity in the frequency range 600 MHz to 6 GHz are determined from measurements of a complex reflection coefficient by using a vector network analyser (VNA) that is connected to the embedded probe via a coaxial cable. Substitution methods for calibration of an inaccessible probe are studied in this paper. These require the VNA with attached cable to be calibrated prior to connecting the cable to the embedded coaxial probe. Measurement of permittivity and conductivity of fluids inside sealed tanks and pipes is needed for monitoring industrial processes, such as fermentation. The authors’ requirement, however, was to allow monitoring of a tissue-equivalent liquid that is contained inside a sealed tank. This tank is a component of a commercial system for rapid, multiple-band measurement of the specific absorption rate (SAR) of mobile phone handsets. Monitoring of permittivity and conductivity is needed to ensure compliance with international standards for SAR measurement. The paper also presents data for a new broadband (600 MHz to 6 GHz) tissue-equivalent liquid that is based on an oil-in-water emulsion. It is demonstrated that over an extended period of time, the liquid is stable, and an embedded coaxial probe enables its properties to be monitored with the required accuracy.

Microwave Complex-Ratio-Measuring Circuits

This chapter reviews the microwave complex ratio measuring (MCRM) circuits which are used for complex reflection coefficient measurement. This MCRM circuit is relatively simple and cost-effective. There are various structures for the MCRM circuit, such as multi-probe transmission line circuits, five-port ring circuits, six-port hybrid coupler-based circuits, switched-reflector circuits, dual-generator circuits, and Wheatstone bridge-based circuits. Each structure of the circuits has its own advantages and disadvantages. In this chapter, the MCRM circuit calibration process has been described in detail.