Garmatyuk Sergey Sergeevich

Звание: Доцент

Степень: Кандидат технических наук

Institute of Radioengineering Systems and Control

E-mail:

View email

Personal page:

https://sfedu.ru/s7/person/ru/ssgarmatyuk

Personal page in english:

https://sfedu.ru/s7/person/en/ssgarmatyuk

Research interests:

THE  INPUT ADMITTANCE METER OF THE HUMAN BODY AND OTHER WHIP ANTENNAS.   Knowledge of  the properties of the human body as an antenna is critical,  for example, to determine -currents in the human body under the influence of radiofrequency electromagnetic fields,  the development of biomedical wearable devices of the remote monitoring of physiological signals and the study of the influence of the human body on a portable communication system. The value of antenna input impedance is necessary to know to match it with the transmitter. If the antenna input impedance depending on the frequency is known it can be determined the antenna operating frequency band of the antenna or the resonant frequency. In some cases, the usage of the properties of the human body electrical conductivity  allows to obtain some advantages in comparison with the usage of the -conventional antennas. For example, you can perform the disguised (hidden) antennas which give the freedom of a human movements  or create new devices, such as home automation, wired and wireless sensors of support. Such sensors are used in alarm systems and podography. Microsoft has suggested to use the human body for transmitting power and information, particularly for producing and receiving external data to the carrier of the electronic devices. Knowledge of the properties of the human body as an antenna can be used to diagnose diseases, as well as to test the hypothesis of the electromagnetic nature of the telepathic communication channel, contributing to the solution of the long-standing dispute between the supporters and opponents of parapsychology.

Currently the electrical parameters of the various human tissues in a wide range of frequencies are known. However, due to the complexity of the problem is much less known about conductivity of the human body as a whole. To investigate the electrodynamic properties of the body offered a variety of models. To calculate the fields and the currents in the human body the anatomical model of a man has been divided one of 16 tissue types such as muscle , fat , bone , blood , etc. It was divided into small cell size of 1/4 ". A model in the form of folding wire antenna suitable for the frequency range from 50 Hz to 110 MHz was proposed and developed , and   currents in the human body in various positions of his hands were calculated. In order to study the electrical properties of men, women and children a liquid model was used. The model is easy to make and optimize for people of different heights. A simple model of the human as an infinite homogeneous cylinder with the diameter 30 cm with dielectric constant ε = 80 and typical blood and muscle tissue conductivity σ = 0,7 S / m. is given .

However, despite the variety of the assumpted models the questions about how well a particular model reflects the properties of a person as an antenna, which parameters of a person (his height, weight, cross sectional area , gender, age, physical - and emotional state and so on .) are still opened and they substantially affect the value of the conductivity of the body. Answers to these questions can be given only with the help of experimental studies.

This paper describes the  meter suitable for determining of the input conductivity of the human body. The different options for its usage and the recommended methods of measurement are given . Necessary calculated ratio is suggested. By comparing the experimental and the calculated parameters of the whip antenna the conclusion of the reliability of measurement results is given. The men input impedance measurement results are given. The device examples that use the human body as –the antenna and suggestions for future research in the field of measurement and the usage of the human body as the antenna.

Research projects:

RANGE METER OF INPUT IMPEDANCE OF WHIP ANTENNAS   Describes operation principle and properties of the original wide-range input impedance meters of whip antennas, as well as the human body used as an antenna. The meters implement a modified method of the Q-meter. A feature of the described meters is the use of tunable two-wire or strip resonators, which allows determining the input impedances of antennas in a wide range of frequencies. It is given a detailed description of the structure of wide-range meters and it is provided information required for their design.

RESONATOR Q-FACTOR CALCULATION FOR WHIP ANTENNA  INPUT IMPEDANCE METERS  The simple relationships for calculating the quality factor of strip resonators with tunable length which are important for practical purposes are obtained. Such resonators are used in the input conductivity meters of whip antennas. The experimental study of such resonators is performed. The results of theoretical and experimental research are in good agreement with each other.

FOOTHOLD REGISTRATION WIRELESS DEVICES  Foothold registration wireless devices (devices for podography) are used for phase registration of foothold and a human or an animal feet transfer while running and walking. It is possible to use them in an alarm system  and to identify people by gait. The main elements of these devices are sensors. To construct a sensor it is used tension effect, piezoelectric effect and other physical phenomena. The contact and capacitive foothold sensors are easier to implement. The first ones are based on the usage of elastic contact elements connecting under foothold. The second sensors use capacity.

The aim of this work is to investigate foothold registration wireless devices, in which an emitter is the object of research. The important advantage of such systems is the lack of contact bounce which is present in the contact foothold sensors. Due to the absence of wire communication between the sensor and receiver devices it is convenient to use these devices in crowded places. In the absence of wire communication and an external antenna in the alarm system it is possible to ensure secrecy.

DEVICE FOR TREMOROGRAPHY   Healthy and sick people can have tremor (shaking). Causes and kinds of tremor are extremely diverse. Tremorographs are used to registrate permanent and free small fluctuations of different parts of hand (static and dynamic tremor). The dynamic tremor is measured at encircling outline of different personal configuration, made in the form of slots on the tremorograph working surface (tablet) Typically the slot width is about 3-5 mm and length is 10-20 cm. The main point of investigation is that a person must hold the probe (rod) into the slot so that not to touch its edges. During the test, the probe should always be immersed in slot about 2-3 mm depth. As the dynamic tremor indicators, the curve passing time, the number of touches, the total time of touches, the factor of assymetric touches are recorded.  The dynamic characteristics of the tremor are related to the properties of attention (volume, stability selectivity, etc.), visual acuity, blood pressure and so on. d. These characteristics change significantly in the development of fatigue having correlated with the dynamics of labor productivity, which allows us to use them to diagnose states of physical and intellectual fatigue, emotional stress, and so on. d. As a result, various options of tremorography are very popular in sports physiology, aviation and space medicine.

НАРАСТАНИЕ АМПЛИТУДЫ КОЛЕБАНИЙ В ТРАНЗИСТОРНЫХ АВТОГЕНЕРАТОРАХ   OSCILLATION AMPLITUDE GROWTH IN TRANSISTOR OSCILLATORS.  Amplitude settling time of self-oscillations is an important parameter of various RF devices. This time also characterizes properties of an oscillator, an active element and oscillatory system.

Let's define amplitude settling time of self-oscillations for Hartley oscillators. In this oscillator incomplete inclusion of a transistor in the oscillatory contour is used and consequently cumbersome expressions for settling time result from derivations.

For simplification of calculations we propose to replace real oscillatory system of the oscillator with an equivalent contour included in the output cascade of the transistor. Resonance impedance of this equivalent contour can be determined using a known expression for incomplete inclusion of a parallel contour.

As the equivalent contour has the same resonance frequency and Q-factor as the actual oscillator, it is possible to define its inductance and capacity. We derive the differential equation of the circuit for Hartley oscillators with this equivalent contour and transform it using the          Van der Pol method.

РАСЧЕТ АВТОГЕНЕРАТОРОВ, УПРАВЛЯЕМЫХ ЕМКОСТНЫМИ ДАТЧИКАМИ. COMPUTATION OF CAPACITOR SENSOR-BASED OSCILLATOR PARAMETERS

Computation of Colpitts oscillator parameters with controlled capacitance is presented. This capacitance can be formed, for example, by a support sensor which provides for the amplitude modulation of the oscillator output, or a capacitance-based microphone which provides for a frequency modulation.

Initial data for computation of oscillator parameters with capacitor sensor can be operational frequency and requirements of its stability, sensor capacitance, power supply voltage, voltage of automatic displacement, Q-factor of the unloaded device and a conduction angle. Starting from the requirements on frequency stability mode intensity and efficiency can be chosen. It is shown that the influence of shot noise in oscillators decreases as current through the transistor (or a vacuum tube) and conduction angle. Recommendations for parameters of oscillators with high frequency stability are given.

Formulas for calculation of an electronic mode of the oscillator and parameters of its oscillatory system are derived. Influence of parasitic inductance in operating electrode chain of a vacuum tube or a transistor on parameters of oscillatory system is explained. Parasitic inductance is formed by inductance of the capacitor in an input chain of the oscillator and by the inductance of the circuit assembly. Depending on the type of the capacitor and quality of assembly the parasitic inductance can reach 1 … 30 nHn. Expressions for calculation of feedback factor of the oscillator and of the input chain capacitance taking into account influence of parasitic inductance are given. This feedback factor is not calculated in known literature but rather is assumed to be between 0.1 to 1.

НАРАСТАНИЕ АМПЛИТУДЫ КОЛЕБАНИЙ В ТРАНЗИСТОРНЫХ АВТОГЕНЕРАТОРАХ.OSCILLATION AMPLITUDE GROWTH IN TRANSISTOR OSCILLATORS

Amplitude settling time of self-oscillations is an important parameter of various RF devices. This time also characterizes properties of an oscillator, an active element and oscillatory system.

Let's define amplitude settling time of self-oscillations for Hartley oscillators. In this oscillator incomplete inclusion of a transistor in the oscillatory contour is used and consequently cumbersome expressions for settling time result from derivations. For simplification of calculations we propose to replace real oscillatory system of the oscillator with an equivalent contour included in the output cascade of the transistor. Resonance impedance of this equivalent contour can be determined using a known expression for incomplete inclusion of a parallel contour. As the equivalent contour has the same resonance frequency and Q-factor as the actual oscillator, it is possible to define its inductance and capacity. We derive the differential equation of the circuit for Hartley oscillators with this equivalent contour and transform it using the Van der Pol method. IV-characteristic of the transistor is approximated by a third degree polynomial. Polynomial coeifficients are defined using values of average steepness of the transistor characteristic at minimum and maximum amplitude of fluctuations.