The main structural element of a reinforced concrete supports: mathematical modeling of mechanical vibrations

The problem of mathematical modeling of a reinforced concrete supports mechanical vibrations is considered. The basic vibrations of the main structural element (a road) are taken into account. The eigenfrequencies of the first three vibration modes of the rod are determined without and with prestressing of the rod. Participation factor of the basic, second and third modes is investigated

The role played by evanescent fields in the process of formation of radiation of combined radiating systems

The problem of active controlling of the structure of fields of combined radiating systems within their near zone is studied. The characteristic size of this zone is on the order of the wavelength and is characterized by the presence of evanescent (nonpropagating) fields, which are formed, among other things, due to the interference interaction of radiators of the system. Using multipole expansions for fields and special summation formulas for such expansions allows one to obtain concise expressions convenient in carrying out numerical calculations. The results of calculations confirm that the evanescent fields’ structure plays a significant part in the process of the formation of the radiation field

Control of the magnitude and spatial distribution of interference energy flows in near fields of systems of identical radiators

The problem of active control for both the magnitude and spatial distribution of individual components of the interference component of the Poynting vector within the near zone of a system of radiators is studied. The characteristic size of this zone is on the order of the wavelength and is characterized by the presence of evanescent (nonpropagating) fields, which are formed due to the interference interaction of radiators. Using multipole expansions for fields and special summation formulas for such expansions allows one to obtain concise expressions convenient in carrying out numerical calculations. The results of calculations confirm the feasibility of the above-mentioned control in principle in solving problems of medium and object sensing

Numerical modeling and experimental investigation of the breadboard model of a near-field interference microscope

A circuit design for technology of near-field interference microwave microscopy using evanescent fields of several active radiators (probes) is suggested and substantiated. The feasibility of providing the spatial overlap of the evanescent fields of two probes representing expanding coaxial conical horns is demonstrated. It is shown that the structure of the electromagnetic field in the region of overlap can effectively be controlled by changing the phase difference of oscillations arriving at inputs of the probes. This technology can be used for diagnostics of liquid media comprising dielectric inhomogeneities, flaw detection, and hygroscopy

Near-field interference microwave diagnostics of cultural plants and wood materials

A schematic solution of the near-field interference microwave microscopy technology is discussed. This solution is implemented in the form of a maximally simplified microscope structure. Testing was con-ducted to determine the capabilities of this microscope. It is shown that technology can be used to solve a number of hygroscopy and defectoscopy problems

Application of broadband microwave near-field sensors for glucose monitoring in biological media

The paper presents results of numerical simulation and experimental testing of a microwave sensor for non-invasive glucose monitoring. The sensor represents a conical horn with a conical conductor inside expanding toward the horn aperture. Such a sensor has a significantly wider passband in comparison with sensors of other designs. It is essential that the sensor geometry provides formation of an extended near-field zone with high electric field strength near the sensor aperture. A clear relationship between the dielectric permittivity of the phantom biological tissue and the frequency dependence of the parameter S11 of the sensor is observed at frequencies in the range from 1.4 to 1.7 GHz. This circumstance can be used to develop a procedure for measuring the glucose level in blood that correlates with the parameter S11 of the sensor. From the viewpoint of monitoring of the glucose content in blood, the most convenient body sensor location is on the hands or feet, in particular, wrists

Control of the magnitude and spatial distribution of interference energy flows in near fields of systems of identical radiators

The problem of active control for both the magnitude and spatial distribution of individual components of the interference component of the Poynting vector within the near zone of a system of radiators is studied. The characteristic size of this zone is on the order of the wavelength and is characterized by the presence of evanescent (nonpropagating) fields, which are formed due to the interference interaction of radiators. Using multipole expansions for fields and special summation formulas for such expansions allows one to obtain concise expressions convenient in carrying out numerical calculations. The results of calculations confirm the feasibility of the above-mentioned control in principle in solving problems of medium and object sensing

The role played by evanescent fields in the process of formation of radiation of combined radiating systems

The problem of active controlling of the structure of fields of combined radiating systems within their near zone is studied. The characteristic size of this zone is on the order of the wavelength and is characterized by the presence of evanescent (nonpropagating) fields, which are formed, among other things, due to the interference interaction of radiators of the system. Using multipole expansions for fields and special summation formulas for such expansions allows one to obtain concise expressions convenient in carrying out numerical calculations. The results of calculations confirm that the evanescent fields’ structure plays a significant part in the process of the formation of the radiation field

Numerical modeling and experimental investigation of the breadboard model of a near-field interference microscope

A circuit design for technology of near-field interference microwave microscopy using evanescent fields of several active radiators (probes) is suggested and substantiated. The feasibility of providing the spatial overlap of the evanescent fields of two probes representing expanding coaxial conical horns is demonstrated. It is shown that the structure of the electromagnetic field in the region of overlap can effectively be controlled by changing the phase difference of oscillations arriving at inputs of the probes. This technology can be used for diagnostics of liquid media comprising dielectric inhomogeneities, flaw detection, and hygroscopy

Near-field interference microwave diagnostics of cultural plants and wood materials

A schematic solution of the near-field interference microwave microscopy technology is discussed. This solution is implemented in the form of a maximally simplified microscope structure. Testing was con-ducted to determine the capabilities of this microscope. It is shown that technology can be used to solve a number of hygroscopy and defectoscopy problems