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Biography Abstract DonNTU Master's portal

 

Khludneva Anna

Faculty: Computer informational technologies and automatics

Department: Automatics and telecommunications

Speciality: Telecommunication systems and network

Theme of master’s work:

“Research and designing of antenna systems which based on reversing mediums for satellite telecommunication systems”

Scientific adviser: professor Khorkhordin Alexander Vladimirovich

 

Summary of research and developments

The antenna systems are integral parts of modern radio aids. They are used to define the direction for the evolving source or investigating positions of many evolving sources in the ambient space. Thus, the problem of operative scanning and manipulation of the directional diagram form is one of current importance for today. Accordingly, the antennas have turned into one of the determinant link of radio systems.

Today the antenna engineering runs up to the ripe degree. As a result of this fact the further development of the antenna systems does not follow the path of creation of fundamentally new antenna types, but improvement of their characteristics and introduction of new methods of their application. For all that, the appearance of new ideas in the antenna engineering is stimulated by the necessity of creation of radio systems with certain characteristics.

So, the purpose of my master’s work is development and researching of antenna system that can do the operative scanning of the directional diagram in the space and also provides the ability to change the shape and width of the directional diagram while scanning within the adjusted rule. There are three problems that’ll be solved in my master’s work:

  1. development of the new method of operative electronic scanning;
  2. development of the double-reflector antenna system;
  3. researching of the characteristics of the antenna system.

There are three methods of scanning realization:

  1. mechanical;
  2. electromechanical;
  3. electrical.

However, mechanical and electromechanical methods of scanning can not satisfy modern demands of round-up’s speed and possibility of tracing for transference of many objects at the same time.
The electrical method of scanning provides the highest speed of scanning. As a rule, electrical scanning is realized in the multiunit antenna array. The implementation of this method is quite difficult because of some difficulties, such as phase errors in the antenna aperture caused by mistakes of some governors, increment of phasing adjustment, error and correlation of units while scanning; additional microwave capacity loss evolving in the governors; relative bandlimitedness connected with the possibility of appearing the secondary principal maximums [1,2].

We offer the method of electronic scanning of the directional diagrams of the reflector antennas which implies making the antenna reflector of reversing materials. The peculiarity of the reversing medium is that it is radioparent, but after experiencing the influence of the keying signal, it acquires the features of the reflective surface. As the reversing medium we offer to use the semi-conductor.

While the constant temperature and absence of evolving, the electroconductivity of the pure semi-conductor or impure semi-conductor is called the dark conduction. After lighting the semi-conductor by some light with the energy of the photons, which is higher than the width of the forbidden gap of the pure semi-conductor or higher than ionization energy of the impure semiconductor, the additional nonequilibrium carrier of the charge appears in the conducting band. As a result, the electroconductivity of the semi-conductor grows.
The appearance of the photo-carrier causes the local changes of all the electromagnetic parameters of the material, such as reflection, refraction and transmission coefficients of the electromagnetic wave.  Under the absence of light, the reversing medium possesses the small dark illumination and it is the radioparent medium [3,4,5].

As the light source can be used powerful sources with approximately sun spectrum.

Such kind of researches which are based on the features of the semi-conductors are provided by pro-rector of the ЮРГУЭС Okorochkov Alexsander Ivanovich. However he doesn’t include reflector antenna systems in the area of his science interests. In Ukraine and, particularly, DonNTU this kind of researches is provided by our science group with our head Ph. D. Khorkhordin Alexsander Vladimirovich and our scientific adviser Paslyon Vladimir Vladimirovich.

We offer the method of scanning, which is based on the lighting the surface of the reversing medium with the intensive light spot of the necessary size and shape. Changing this size leads to changing the width of the directional diagram and its shape in the given plane. It is obvious that the width of the directional diagram of the antenna depends on the size, shape and orientation of the light spot, e.g. it becomes narrower with the growth of the light spot. During the transference of the light spot on the surface of the reflector, we implement scanning of the directional diagram in the space. At the same time, the speed of scanning is limited only by the transmission speed of the reversing medium from the non-conducting state to the conducting, i.e. it is determined by the life time of nonequilibrium carriers of current, and by the speed of the light spot transfer; the rule of shift of the light spot disposition, as well as the directional diagram, can be arbitrary [6-9].

Thus, this method both makes it possible to generate the directional diagram with the given form and width in the microwave range and to command the directional diagram while we are scanning, using the adjusted rule, that ensures the trajectory flexibility and the scanning high speed.

The method of scanning suggested is the base of functioning of the spherical double-reflector antenna system which was designed and patented.

This antenna system consist of main and auxiliary reflectors that have the form of concentric spherical surface and feed elements that are based near the surface of the main reflector. The main and auxiliary reflectors are made of the radioparent material, but the inside surface of the auxiliary and the outside surface of the main reflector are covered by the reversing material. The polarization of the feed elements can be free. The antenna system has two  sources of command signals. The structural arrangement is pictured on the figure 1.


Figure 1 – Animation of principle of operation of the double-reflector spherical antenna (amount of frames 5, amount of loops 5, capacity 2,68kB)

 

The device functions in the following way. The source of the command signals 4 influences on the surface of the reversing material in regions 5 with the help of  command signals on the reflector 1 and 2. The reversing medium possesses small dark illumination in the nonexcited state that’s why the reversing medium is radioparent in this state. The intensive light spot influences on the reversing material and in these regions of the reversing surface we can observe the sudden changes of all parameters of the reversing material. They are conditioned by generating the nonequilibrium carriers of current, which change the electromagnetic characteristics of the reversing material. Thus, the reversing material acquires metallic features that makes possible to reflect electromagnetic waves. That’s why more than one ray of the directional diagram is formed.
We can change in turn the conductivity of different regions of the semi-conductor with the help of moving the spots of the command influence. As a result we have a circular scanning of the directional diagram rays in the space. The width of the directional diagram depends on size, form, and orientation of the excited regions [10].

Thus, we have developed the new method of operative electronic scanning of the directional diagram in space with possibility of changing form and width of the directional diagram while scanning using the adjusted rule. We also designed the construction of the spherical double-reflector antenna that is based on this method of electronic scanning. We have received the useful model patent and the positive solution about the patent for invention. Moreover, we have done modeling process of reversing features of the semi-conductors. And now we are working on determination of the parameters of these materials we need for our antenna system.

 

References

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  2. Филькенштейн М.И. Основы радиолокации. Изд. 2-е, перераб. и доп. - М.: Радио и связь, 1983. – 536 с.
  3. Спиридонов Н.С. Основы теории транзисторов. - К.: Технiка, 1969. – 300 с.
  4. Зуев В.А., Саченко А.В., Толпыго К.Б. Неравновесные приповерхностные процессы в полупроводниках и полупроводниковых приборах. - М.: Советское радио, 1977. – 256 с.
  5. Волькенштейн Ф.Ф. Электроны и кристаллы. – М.: Наука, 1983. – 128 с.
  6. Вайнберг И.А., Павельев В.А. Исследование амплитудно-фазовой структуры ближнего поля антенны СВЧ при помощи фотоуправляемых полупроводниковых панелей. Радиотехника и электроника,   - М.: Наука, 1971. №9 – 1685 с.   
  7. Вайнберг И.А., Вайнберг Э.И., Павельев В.А. Индикация структуры электромагнитного поля при помощи неравновесных носителей тока в полупроводниках. Радиотехника и электроника,   - М.: Наука, 1971. №3 – 1971
  8.  Нашельский А. Я. Технология полупроводниковых материалов, - М.: Наука, 1973.
  9. Хлуднева Г. В., Михайлов М. В., Пасльон В. В. «Нові антенні системи електронного сканування»\ «Излучение и рассеяние электромагнитных волн» ИРЭМВ-2007, г. Таганрог, Россия, 25-30 июня 2007 г.  
  10. Деклараційний патент № 25901 Двохдзеркальна сферична антена\ Хлуднева Г. В., Михайлов М. В., Ольшевський А. Л., Пасльон В. В