The article presents a model of a near-field sensor for non-invasive glucose monitoring. The sensor has a specific design and forms a rather extended near-field. Due to this, the high penetration of electromagnetic waves into highly absorbing media (biologic media) is achieved. It represents a combined slot antenna based on a flexible RO3003 substrate. Moreover, it is small and rather flat (25 mm in diameter, 0.76 mm thick). These circumstances are the distinguishing features of this sensor in comparison with microwave sensors of other designs. The article presents the results of numerical modeling and experimental verification of a near-field sensor. Furthermore, a phantom of human biological media (human hand) was created for experimentation. In the case of numerical modeling, the sensor is located close to the hand model. In a full-scale experiment, it is located close to the phantom of the human hand for the maximum interaction of the near-field with biological materials. As a result of a series of measurements for this sensor, the reflection coefficient is measured, and the dependences of the reflected signal on the frequency are plotted. According to the results of the experiments carried out, there is a clear difference in glucose concentrations. At the same time, the accuracy of determining the difference in glucose concentrations is high. The values of the amplitude of the reflected signal with a change in concentration differ by 0.5–0.8 dB. This sensor can be used for developing a non-invasive blood glucose measurement procedure.

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.

538.56Results of theoretical and experimental investigations of artificial metamaterials based on composite of straight and circular conductors for radio wave range are presented. It is demonstrated that for small conductor sizes, nonresonant character of metamaterial properties of the artificial medium is retained. The possibility of application of metamaterials for increasing resolution in radio tomography is discussed.

It is shown theoretically and experimentally that in the field of an electromagnetic radiator located in an absorbing medium, there exists a virtual surface that encompasses the near-field zone and is referred to as causal in the present study at which the field undergoes a second order phase transition. This transition is characterized by a rapidly changing phase and conversion of the energy of the quasistatic/reactive field into the energy of the field in the state of radiation. Behind the causal surface, the law of phase change sufficiently quickly acquires a linear character, and the field strength decreases with an increase in the distance following either an inverse-square law or an exponential function depending on the absorption coefficient of the medium, which is manifested through the formation of an intensively absorbing layer. Within the near zone, exponential attenuation is not observed. The size of the near zone depends on the frequency and the refractive index of the medium. Based on the studies performed, a new approach to the problem of sensing of absorbing media is suggested.

The article is about the development of a new non-destructive microwave method for measuring the electrophysical properties of materials, based on the method of transmission and reflection of a plane monochromatic wave through layered materials. The method has been verified by the results of numerical and field experiments. A data processing technique is described for obtaining complex values of dielectric and magnetic permeability based on an original measurement scheme. Based on the results of mathematical calculations, the laboratory model was created using an ultra-wideband antenna and a parabolic mirror. The optimal distance of the antenna from the parabolic mirror for focusing the electromagnetic field has been determined based on the simulation. Testing was carried out in the frequency range 3–13 GHz on two samples of materials (plexiglass and textolite) with known electrophysical properties. The obtained results showed the reliability of the developed method and its applicability. The measurement error was less than 2%.

Abstract. This article presents the results of numerical and computer modeling of the flat closed conductor with different variants of arrangement. The interaction of the conductors is examined and the results of active and reactive part of the Poynting vector for each structure is presented. According to the results the model with identical parameters for each element was built and examined for the presence of metamaterial properties. IntorductionBack in the late 1960s, V.G. Veselago predicted the unique properties of materials with a negative real part of the permittivity and permeability [1]. Later, a special interest was aroused by the works of D. Pendry of the possibility of developing "superlenses" allowing overcoming the diffraction limit [2].Previously, the authors of this work presented the possibility of metamaterial creation for the radio range as an artificial composite medium made up of a certain oriented linear and circular conductors [3,4]. Such a medium may have a negative refractive index. In the theoretical consideration of the works above stated the approach of not interacting elements has been introduced. For more complete analysis when creation of the structure with the properties of the metamaterial it is necessary to consider the influence of elements on each other at the incidence of a plane wave [5]. Modelling the interaction of confined conductorsThe problem of the circular conductors' structure arrangement is sufficiently capacious. It is necessary to select geometric dimensions of the elements, their orientation, and the distance between them. To estimate the interaction between the individual elements of the array we will consider Poynting vector along the axis of distribution of the incident plane wave [6,7].To consider the active (Re(P)) and reactive (Im(P)) parts of the Poynting vector it was provided a modeling using CST Microwave studio software package. This product allows considering different characteristics of the electric (E) and magnetic (H) fields.

The article presents the design of the near-field probe, which is a combined emitter (a combination of a symmetric dipole and an annular frame). The design of the probe allows forming a prolonged zone of the near-field. This effect can be used for in-depth penetration of the field in media with high absorption, without loss of information. Particular attention in this article is given to a detailed study of the interaction of the field created by this probe on plane-layered biological media. A theoretical analysis of the interaction of the electromagnetic field was carried out in a wide frequency band with a model plane-layer biological medium containing blood vessels of shallow depth using the proposed probe design. Conclusions are drawn about the depth of penetration of a useful signal into different media-analogs of biological tissue. This study is necessary to consider the possibility of using this probe for non-invasive measurements of blood glucose concentration. The studies were carried out using numerical simulation in the CST (Computer Simulation Technology) Microwave Studio environment. All biological tissues were simulated over a wide frequency range from 10 MHz to 10 GHz.

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