Faculty of Automatic Control, Electronics and Computer Science

Teaching and research work

For all the years of work, Prof. Zagajewski conducted very carefully prepared lectures, most appreciated by successive generations of students. His achievements include many books and textbooks, constantly updated and adapted to the new teaching needs. The first such book was a textbook published shortly after the war (1949) entitled "Radiotechniczne urządzenia nadawcze“ (Radio Technical Broadcasting Equipment) [1], which was repeated in several editions until 1961. The second one was a book entitled "Elektronika przemysłowa” (Industrial Electronics) [2], first published in 1953 and reworked many times with different teams of collaborators. The subject was completely new in world literature at that time, and the need for this book was confirmed by its constant reissuing in an updated form; its sixth edition was published in 1975, and the Russian translation in 1976. Among the books published later, the monographic study of applied and industrial electronics systems, whose fourth edition was published in 1978 under the title " Układy elektroniki przemysłowej” (Industrial Electronics Systems) [3], deserves special attention.

Prof. Zagajewski was the supervisor of more than 200 master's theses and the supervisor of 15 doctoral theses. Several of his alumni received the rank of Associate Professor and the title of Professor.

Although the original scientific activity of Prof. Zagajewski in different periods also included many other threads, the Professor's main field of interest was the theory of electrical circuits as applied to electronic systems. Among Professor’s most important original theoretical works, several topics can be distinguished:

• Works concerning the analysis of electronic generators - the constancy of the frequency of vibrations, linear and nonlinear effects in these generators, the rise time of vibrations, etc. The harmonic theory of Prof. J. Groszkowski was extended by T. Zagajewski in his Ph.D. thesis [4] and later works by relating the harmonic content to the shape of the characteristics of the nonlinear element. It allowed him to significantly extend the area of application of this theory to the issues of optimization of electronic generators.
• Theoretical works on electrical circuits used in electronics. The most important of them can be regarded as the generalization of the concept of duality of electric circuits [5], its application to long lines [6,7], as well as to nonlinear circuits and circuits with time-varying parameters [8,9]. The concept of duality enabled Professor Zagajewski to take a new approach to the issue of optimization of electronic generators regarding frequency constancy and nonlinear distortions [10, 11].
• Another subject of the Professor’s work is the issue of fused circuits, i.e., circuits with the same topology and elements transformed from R to C or from R to L and vice versa [12]. Practical conclusions from such transformations predict the possibility, significant for monolithic circuit applications, of replacing inductance in resonant circuits with negative resistances [13].
• The similarity of electric circuits was defined by Professor in a completely general way in works [14-17]. Four types of circuit similarity were distinguished there, the exceptional cases of which are duality and fusion. For these four types of similarity, simple relations between transmittances of circuits as well as currents and voltages in corresponding branches of circuits, were defined.
• The important works [18-21], in which the Professor researched modifications and applications of Walsh functions to the analysis of impulse systems.

After turning 70 (in 1983), Professor Tadeusz Zagajewski retired. However, he did not stop his scientific work. In his recent theoretical works, he returned to the fundamental issues of nonlinear feedback in amplifiers, electrical symmetry of circuits, instability of generator frequencies, and determination of the instantaneous frequency [22]. He was also a frequent guest at the Institute of Electronics, where he conducted classes for many years.

Professor Tadeusz Zagajewski died in the fall of 2010 at the age of 98. He is buried at the Central Cemetery in Gliwice. He deserves our grateful memory and respect for his contribution to science in Poland. He was a model of righteousness, modesty, and honesty in difficult times. On December 12, 2012, the "Jubilee Session on the occasion of the 100th anniversary of the birth of Professor Tadeusz Zagajewski, founder of Industrial Electronics in Poland" was held at the Faculty of AEiI under the patronage of SUT’s Rector. In the Jubilee Celebration Committee, apart from the Professor's students and associates, there were representatives of the Polish Academy of Sciences, PTETiS, and SEP. The Professor's daughter and son took part in the session and accompanying events.

Professor’s son Adam Zagajewski is one of the greatest Polish poets. His daughter Ewa Zagajewska-Fabrycy was a researcher at the Silesian University of Technology and the Szczecin University of Technology.