Home: My mother taught me Arithmetic. She was a school teacher at Vivekananda High School (Primary Section), Jamshedpur. I dedicated one of my books, published by World Scientific, authored by me to her. My elder sister Bharati Basu (Dey) taught me Mathematics and Physics. She was first a school teacher at Vivekananda High School and Sacred Heart Convent and then was a librarian at CSIR-National Metallurgical Laboratory all at Jamshedpur. I dedicated one of my books, published by Universities Press, authored by me, to her. (My father died when I was two years old).
School: SwamiJi Biren Mukherjee taught me Elementary Mathematics and Mr. Shanti Moulik taught me Bengali and English literature in my school, Vivekananda High School (Arts stream) (Ramkrishna Mission), Sakchi, Jamshedpur (Bihar School Examination Board).
Intermediate college: Professors M. M. Mahnaty and A. Bannerjee taught me Physics and Professor Sarojit Mitra taught me English literature at Jamshedpur Cooperative College (Science stream) (Bihar University).
Undergraduate and postgraduate colleges: Professors Hara Prasad Dey, Chandi Charan Banerjee, and S Banejee taught me Physics in B. Sc Honours programme at Vidyasagar College, Kolkata (Calcutta University). Professors J. N. Bhar, Santosh K Sen, Mukti Sadhan Basu, Arun K Chowdury, Mrinal Kanti Dasgupta, Nirmal Baran Chakraborty (N. B. Chakrabarty), Anadi Nath Dawn, B. R. Nag, Amarnath Chakraborty, Arun K Sen, P. Dhar Bhowmik, Sanjit Chatterjee, and others taught me Radiophysics and Electronics at Institute of Radiophysics and Electronics (INRAPHEL) (Calcutta University) in B. Tech and M. Tech programmes. The teaching of Professors N. B. Chakraborty and B. R. Nag motivated me to take up my research area as applied electromagnetics.


MENTOR OF MY DOCTORAL WORK: I was fortunate to come across Professor Nirmal B. Chakraborty -versatile genius- who taught us electromagnetic theory in our B. Tech and M. Tech classes at INRAPEL (Calcutta University). He mentored my doctoral work when I had joined him at IIT-Kharagpur after leaving my job at DRDO-Defence Electronics Research Laboratory (posted at Field Research Station, Jamnagar). Professor Chakraborty was D. Sc (Calcutta University) in the area of communication engineering. I wished to work in this area. However, he saw the book “Plasma Physics” by S. Chandrasekhar in my possession when I had met him with a request to accept me as his doctoral student. Instead of a doctoral research topic on communication engineering he chose my topic on nonlinear effects in double-stream and beam-plasma amplifiers. Later on I came to know his papers related to this area: (i) N.B. Chakraborty, “Lower frequency pumping of electron beam parametric amplifiers,” Int. J. Electron., vol. 8, no. 3, 161-165 (1960) and N.B. Chakraborty, “Analysis of fast-wave amplifiers for transverse field parametric amplifiers,” Int. J. Electron., vol. 10, no. 2, 147-151 (1961). Professor Chakaraborty taught me how to use Eulerian hydrodynamic approach to study nonlinear effects such as harmonic generation and frequency mixing in electron beam and plasma devices. Later on I motivated my postgraduate and doctoral student Dr. Subrata Kumar Datta to use the approach to study harmonic generation and intermodulation distortion in travelling-wave tubes. Professor Chakaraborty founded Microelectronics Centre at IIT-Kharagpur with the active support and major contributions from Professor Samir Kumar Lahiri (who was my M. Tech classmate at INRAPHEL). At some point of time, while working for my Ph. D degree, I left IIT-Kharagpur and joined Regional Institute of Technology (now NIT), Jamshedpur and continued my research there obtained my Ph. D degree from Calcutta University. While working for my Ph. D degree I was immensely helped by Mrs. Jharna Chakraborty (wife of my Ph. D mentor and whom we used to call as ‘Boudi’ meaning ‘elder sister-in-law’); Professor Lahiri was then lecturer at IIT-Kharagpur, and he and his family, extended extreme moral support to me during my frequent visits to IIT-Kharagpur from RIT-Jamshedpur in connection with the writing of my Ph. D thesis.

Professor Mrinal K. Das Gupta

Provided me a scholarship to initiate my doctoral research under his mentorship at INRAPHEL (Calcutta University) in the area of radio astronomy. Professor Das Gupta was internationally acclaimed for his work at the University of Manchester with Robert Hanbury Brown and Roger Jennison in the early 1950s on the study of the apparent angular structures of two radio sources, Cygnus A and Cassiopeia A, using the intensity interferometers at radio wavelengths. However, without completing my work at INRAPHEL I joined DRDO-Defence Electronics Research Laboratory (DLRL), Hyderabad and was field-stationed at INS-Valsura, Jamnagar. Subsequently, I left DLRL to join IIT-Kharagpur for my doctoral work under the mentorship of Professor Nirmal B Chakraborty as I stated earlier. Interestingly, “Mrinal”, which is the name of my first doctoral mentor at INRAPHEL, is the ‘anagram’ of “Nirmal”, which is the name of my second doctoral mentor at IIT-Kharagpurone name leading to the other name simply by rearranging the letters in their names. During his official visits to Banaras Hindu University, Professor Das Gupta preferred to stay with us in our home instead of the university guesthouse.

Professor D.T. Swift-Hook

Director and Secretary of the World Renewable Energy Network (, when he was Head of a Research Division at the Central Electricity Generating Board, UK, motivated me to improve our analytical study on helical slow-wave structures of travelling-wave tubes through his pioneering paper: Swift-Hook, D. T., 1958. “Dispersion curves for a helix in a glass Tube” IEE, Vol. 105B, pp. 747-55. Commenting on one of my papers, co-authored by Dr. A. K. Sinha, on a helix surrounded by a number of continuous dielectric tubes of different values of permittivity increasing in the radial direction, that provided controlled dispersion for widening the bandwidth of a TWT, he suggested me through a handwritten letter to take tapered-cross-section discrete dielectric supports of the same material instead of a number of dielectric tubes of different permittivities. Professor Swift-Hook honoured me by a felicitation dinner at London since I had cited his paper (loc. cit.) for the maximum number of times. Interestingly, he also worked in the area of double-stream amplifier of interest to my doctoral work and wrote a pioneering paper: Swift-Hook, D. T., 1960 “Validity of the Theory of Double Stream Amplification” Rev., Vol.118, p. 1-5.

Dr. James A. Dayton

Considered me to be one of his most dependable reviewers when he was Editor of IEEE Electron Devices from 1994 to 1999. He invited me to become a charter member of Technical Committee on Vacuum Electronic Devices of the IEEE Electron Devices Society, which he as well as I served from 1998 to 2003. Because of my service as a reviewer and “being aware of” my “technical contributions” to our field, Dr. Dayton invited me to become a charter member of the Committee. He as well as I served the Committee from 1998 to 2003. Dr. Dayton highly appreciated me advocating at IVEC-2003 held at Seoul that IVEC should be organizes in India, and subsequently Dr. Lalit Kumar organized and the first ever IVEC-2011 at Bangalore, India.

Professor R.G. Carter

Took the initiative in inviting me to Lancaster University, UK during the summer of 1993 under the British Council programme: Academic Link Interchange Scheme to collaborate with him in the area of helical slow-wave structures. For this purpose, I was chosen by CSIR with the initiative of Dr. S. S. S. Agarwala of CSIR-CEERI, Pilani as the ‘third partner’ from Banaras Hindu University in the scheme originally involving the two partners, namely, CSIR-CEERI, Pilani and Lancaster University. Dr. Ping Wang, a post-doctoral research scholar at Lancaster University, was then validating our theory on helical slow-wave structures of TWTs against her measurement (Wang, P., Carter, R.G. and Basu, B.N., “An improved technique for measuring the Pierce impedance of helix slow-wave structures,” Proc. 24th European Microwave Conference, Cannes, pp. 998-1003, September 1994). During my stay at Lancaster University, I developed a rigorous theory of measurement of the interaction impedance of a helical slow-wave structure using non-resonant perturbation technique. Coming back to India I took an initiative for the development of an experimental setup for the purpose of this measurement (S. J. Rao, S. Ghosh, P. K. Jain, and B. N. Basu, “Non-resonant perturbation measurements on dispersion and interaction impedance characteristics of helical slow-wave structures,” IEEE Trans. Microwave Th. & Tech., vol. 45, pp. 1585-1594 (1997)).

Professor M.M. Mahanty

Delivered the very first lecture that I attended in my college life as a student of Intermediate Science, at Jamshedpur Cooperative College, Jamshedpur. A teacher par excellence with God-gifted melodious voice he used to thoroughly explain the principles of Physics both in our theory and practical classes and thus infused in me the interest in the subject. It is because of his excellent teaching, even though I had Arts Stream background in school, it became possible for me to catch up with my classmates who had the advantage of having Science Stream background in school. Later on Professor Mahanty joined Regional Institute of Technology (RIT) (now known named as National Institute of Technology (NIT)), Jamshedpur and significantly contributed to its growth. I also joined RIT, Jamshedpur and thus got more opportunity to learn from him. Eventually, we developed a family relationship. Subsequently, I left RIT (NIT), Jamshedpur to join Electronics Engineering Department, Institute of Technology of Banaras Hindu University (now known as IIT-BHU), Varanasi and younger son Professor Ranjit Mahanty of my teacher Professor Mahanty, also joined Electrical Engineering Department of the same Institute, and has become now internationally acclaimed for his research in power electronics; and interestingly elder son Professor R.N. Mahanty of my teacher Professor Mahanty joined the Institute that I had left, namely, NIT, Jamshedpur and now heads Electrical Engineering Department of the Institute.

Dr. S.S.S. Agarwala

Dr. S.S.S. Agarwala was leading the Vacuum Tube (VT) area of CSIR-CEERI, Pilani when I joined CEERI in September 1977. He, having done his own doctoral work at Imperial College in London in the area of TWTs, motivated the VT area of CEERI to develop the first ever TWT in India. I was a member of the team led by Dr. S.N. Joshi to develop this TWT in the country. Dr. Agarwala provided me a theoretical formula to check the design of the helix of the tube. This urged me to develop the analysis of helical slow-wave structure and hence deduce the formula. He was a man of strict discipline and integrity, and would not allow anyone to bypass the dictated norms of the Institute. He was very much conversant with the administrative rules of CSIR with respect to the finance in particular. One and all at CEERI depended on him regarding the purchase of equipment and consumables and know which materials to be used for what purposes. When I asked him to permit me to develop the analysis of helical slow-wave structure, he not only gladly permitted me to do so but also provide me with the relevant literature. That was a great help considering the non-availability of wide internet facilities in India at that time. During the short span of only about nine to ten months of stay (from 19th September 1977 to 28th July 1978) as Scientist at CEERI, I developed, with the support and encouragement from Dr. Agarwala, two technical reports as follows:
(1) CSIR-CEERI-IR-01/VT/78: B.N. Basu and S. N. Joshi: Equivalent circuit analysis of a helix in free space.
(2) CSIR-CEERI-IR-02/VT/78: B.N. Basu: Field analysis of dielectric supported and shielded sheath helix.
While correcting the manuscripts of the above two reports Dr. Agarwala taught me the art of technical writing. Later on, I dedicated the book authored by me: B. N. Basu, “Technical Writing,” Prentice-Hall of India, New Delhi (2007) to Dr. S.S.S. Agarwala. Further, Dr. Agarwala also provided me with literature as required for the measurement of AM-to-PM conversion coefficient of the TWT that we had developed. The measured data evidenced the strength and capability of the TWT development group at CEERI to fetch the first ever sponsored project on the development of a space-TWT at CEERI. Dr. Agarwala continued to maintain a collaborative link with me after I had left CEERI. He took the initiative and pivotal role in the offer of the prestigious position of Distinguished Visiting Scientist of CSIR at CEERI to me while I was at Banaras Hindu University (BHU). I modestly grabbed the offer. This was a turning point in my research career, and gave me an opportunity to work with the scientists of CEERI and author numerous research papers with them. This also gave us an opportunity to provide guidance to carryout the doctoral work of many of CEERI scientists under the external PhD registration scheme of BHU. Dr. S.S.S. Agarwala played a very special role in shaping my research career, and I am grateful to him for ever!

Professor N.C. Vaidya

Professor N.C. Vaidya founded Centre of Research in Microwave Tubes (CRMT) at Electronics Engineering Department in Banaras Hindu University (BHU) (now IIT-BHU). He met me at my residence in Jamshedpur (where I was working as Assistant Professor at Regional Institute of Technology (now known as National Institute of Technology), while he was Professor and Head of Department there. He encouraged me to join BHU. I joined BHU and got the opportunity to work with him. Professor Vaidya significantly contributed to the indigenous development of electron microscopes in India during his tenure of stay at CSIR-CEERI, Pilani and BHU. He nourished at CRMT research in the area of klystrons, travelling-wave tubes and cathodes. We dedicated our book: Vishal Kesari and B. N. Basu, High Power Microwave Tubes: Basics and Trends, Volume 1 and Volume 2, Morgan and Claypool Publishers, San Rafael (California)/Bristol: IOP Publishing (2018) to Professor N.C. Vaidya.

Dr. Amarjit Singh

Dr. Amarjit Singh was Director of CSIR-CEERI, Pilani when I joined CEERI in September 1977. I used to see him taking part in tube-processing in the pump station at CEER despite his being heavily occupied with the administrative work of the institute. He took a leading role in the initiation of R&D in the area of magnetrons in vacuum tube division of CEERI. He nourished the system and the microelectronics divisions of CEERI, too. I very often exchanged my ideas in the analytical understanding of travelling-wave tubes (TWTs)-in particular, helical slow-wave structures of the device-with him. He trusted me on the measurement of the AM-to-PM conversion coefficient of the first ever TWT developed in the country at CEERI by a team led by Dr. S.N. Joshi under the guidance of Dr. S.S.S Agarwala. Dr. Singh encouraged me continuing my research in the area of TWTs after I had left CEERI to work first at NIT, Jamshedpur and then at BHU, Varanasi. At one point, he asked me to analytically investigate into the effect of asymmetry of dielectric helix-support rods of a helical slow-wave structure, whether it is with respect to their angular positioning or their permittivity values. I passed on the problem to Dr. A.K. Sinha of CEERI, whom earlier I had mentored his doctoral research, who made me and Dr. Singh proud by solving the problem and documenting his analytical solution to the problem in the form his research journal papers. Dr. Singh after his retirement from CEERI focussed on his research on the efficiency enhancement of a gyrotron by improved design of depressed collectors. We are grateful to Padma Bhusan Dr. Amarjit Singh for his constant encouragement in our R&D efforts in the area of vacuum electron devices.

Dr. Lalit Kishore

Dr. Lalit Kishore, Head, Physics Department of Regional Institute of Technology (RIT) (now named as National Institute of Technology), Jamshedpur, who carried out his doctoral research at University of Southampton, UK in the area of microwave spectroscopy, suggested me to join his Department as a teacher (Assistant Lecture to start with) with the hope that we would work together to start an M. Tech course there. He saw to it that I get adequate time for doing my research in the Department. I used to attend, rather unofficially, his M. Tech class in Electromagnetic Field Theory at Electrical Engineering Department in RIT. Further, he allowed Dr. A. K. Sinha, the then doctoral student with him, to work with me in the area of electromagnetic analysis of helical slow-wave structure of a travelling-wave tube. I owe to Dr. Kishore, a teacher par excellence, for teaching me the basics of electromagnetic theory and clearing my doubts in the subject thereby enthusing me to study the subject further.

Dr. G.S. Sidhu

Dr. G.S. Sidhu was leading the team at CSIR-CEERI, Pilani engaged in the development of the klystron and the carcinotron tubes when I joined CEERI. We were the alumni of the same institute, namely, Institute of Radiophysics and Electronics, Calcutta University that brought us closer. He was a pious man making a holy place in his house for worship (Gurudwara) for the believers of Sikhism at Pilani. After leaving Pilani Dr. Sidhu established in 1994 Pilani Electron Tubes & Devices Private Limited at Sagrur, Punjab to manufacture a wide array of electron tubes for industrial RF induction heaters and RF dielectric heaters. We learnt a lot from his knowledge in tube technology and philosophy of life.

Professor S.K. Srivastava

Professor S.K. Srivastava founded Centre for Research in Microelectronics (CRME) at Electronics Engineering Department in Banaras Hindu University (BHU) (now IIT-BHU). Subsequently, he established Centre of Advanced Study (CAS) of University Grants University in the Department. Professor Srivastava highlighted the R&D activities of Centre of Research in Microwave Tubes (CRMT) of the Department at different tenures while he was Coordinator of CRME, Coordinator of CAS, and Coordinator of CRMT and also when he was Head of Electronics Engineering Department. I joined CRMT of the Department on lien from Regional Institute of Technology (RIT) (now known as National Institute of Technology), Jamshedpur. However, Professor Srivastava pursued me to leave my lien at RIT and continue to work at CRMT. I had the pleasure of working with Professor Srivastava in coordinating research and administrative activities at CRMT and CAS of the Department. We were also involved in the management of hostels of the Institute. After our respective retirements from BHU, we spent some time of ours at College of Engineering and Technology (CET) at Moradabad, which eventually became a university¾IFTM University. We hosted, at CET in Moradabad, a national conference of Vacuum Electronic Devices and Applications Society (on 18-19 November, 2010) chaired by Professor Anupam Srivastav (son of Professor S. K. Srivasata), who was then the Director of CET. Leave aside his R&D contributions and success in establishing infrastructural setup in the area of microelectronics, Professor Srivastava (SK) significantly contributed to uplifting the standard of education in engineering colleges in India through his services via All India Council for Technical Education, India and National Board of Accreditation, India.

Professor R.K. Jha

Professor R.K. Jha had been leading the activities in the area of Microwave Engineering at Electronics Engineering Department in Banaras Hindu University (BHU) (now IIT-BHU) when I joined the Department. He as the Coordinator of Centre of Research in Microwave Tubes (CRMT) of the Department encouraged my research in the area of microwave tubes. Further, Professor Jha helped me to make a proposal to University Grants Commission (UGC), Government of India for the sustenance of R&D activities at CRMT following the completion of a DOE-sponsored project and also create the posts of teachers and scientists at CRMT. The proposal was granted by UGC and thus we sustained our R&D activities at CRMT. At the suggestion of Professor Jha, I prepared a base paper for a proposal for developing the first ever gyrotron in the country, which he presented at a concerned forum of Department of Science and Technology (DST), Government of India. Subsequently, his effort evolved a multi-institutional project sponsored by DST on the development of a gyrotron for fusion plasma heating¾BHU being one of the five participating institutions of the project. I joined Professor Jha in monitoring the activities of the project as members of the Steering Committee of DST. The involved institutions of the project gratefully acknowledge Professor R.K. Jha for his support and encouragement in the successful development of the first ever gyrotron in the country.

Professor S.C. Dutta Roy

Professor S.C. Dutta Roy, a well known teacher and scientist in the areas of network synthesis, solid state circuits, distributed networking and analog & digital signal processing, is one of my well wishers. We both are alumni of Calcutta University and studied at Kolkata¾ Vidyasagar College and Institute of Radiophysics and Electronics. However, we first met much later in a meeting of a government constituted committee which he chaired and which I attended as its member. Thereafter we met him a good number of times in similar meetings and technical conferences, and I learned there a lot from him on various subjects including music, too. I remember, I edited the first draft of his article on Abdul Karim Khan, one of the most melodious Indian classical musicians: S.C. Dutta Roy, “Ustad Abdul Karim Khan: The Man and His Music,” India International Centre Quarterly, Vol. 40, No. 2, Autumn 2013, pp. 64-78 ( Professor Dutta Roy wrote the Forewords of two of my books (“Technical Writing,” Prentice-Hall of India, New Delhi (2007) and “Engineering Electromagnetics Essentials,” Universities Press, Hyderabad (2015)); I am blessed!

Dr. Lalit Kumar

Dr. Lalit Kumar, who developed the simulation code PIERCE for the design of electron guns and collectors for vacuum electron devices, has been my friend since September 1977 when we worked together as scientists at CSIR-CEERI, Pilani. Even after leaving CEERI, I, as Distinguished Visiting Scientist of CSIR, collaborated with Dr. Kumar in the design of vane-loaded helical slow-wave structures and thus we developed empirical methods for designing such structures for wideband electronic warfare TWTs, by taking into account the effects azimuthal harmonics due to the angular positioning of the vanes around the helix. Dr. Kumar significantly contributed to indigenous development of strategic microwave tubes in India as Director, DRDO-MTRDC, Bangalore. There I collaborated with him through project reviews, lectures, etc. as its Consultant. Dr. Kumar also served DRDO as Chairman, Centre for Personnel Talent Management (CETAM). He is well known for very successfully conducting the IEEE International Vacuum Electronic Conference IVEC-2011 as its Chairperson. I have the privilege of reviewing papers for IEEE Transactions on Electron Devices which Dr. Kumar serves as its Editor.

Dr. S.N. Joshi

Dr. S.N. Joshi was leading a competence development project at CSIR-CEERI, Pilani for the experimental realization of helix TWT under the guidance of Dr. S.S. Agarwala when I joined his team in September 1977. Hence, I enjoyed with Dr. Joshi the experimental characterization of the first ever TWT developed in India. Further, he as well as Dr. S.S.S. Agarwala motivated me to develop the field and equivalent circuit analyses of helical slow-wave structure of a TWT during my short stint of stay at CEERI as scientist. Subsequently, he helped me to strengthen our analytical research supporting me whenever I had visited CEERI from Banaras Hindu University (BHU), Varanasi as Distinguished Visiting Scientist of CSIR. Further, we two together worked in establishing MoUs between BHU, Varanasi and CEERI, Pilani and between Supreme Knowledge Foundations Group of Institutions, Mankundu (which I serve at present as Adjunct Professor) and CEERI, Pilani. Moreover, we have been family friends for nearly four decades and I am grateful to Dr. Joshi for his support throughout my modest attempts for doing fruitful research.

Dr. J. R. M. Vaughan

Dr. J. R. M. Vaughan, from Litton Industries, San Carlos, California, visited CSIR-CEERI, Pilani sometime in 1987 to deliver a series of lectures on electron guns. About a month earlier, I delivered a preparatory talk on electron guns at CEERI on invitation from Dr. Amarjit Singh, the then Director of CEERI. Dr. Vaughan came across my lecture note which was kept in a drawer of a table in the dining hall of the guesthouse of CEERI. I was a bit embarrassed to hear Dr. Vaughan referring to some of the equations of his lecture as equation numbers such and such of of the lecture note of B.N. Basu-someone so little in front of such a renowned scientist as he was. In the guesthouse, I asked him a question with reference to his pioneering paper referred to as the bible of electron gun designer of O-type tubes: J. R. M. Vaughan, “Synthesis of the Pierce gun,” IEEE Trans. Electron Devices, Vol. ED-28, pp. 37-41 (1981). My joking question to him was why the ‘throw’ of his paper on the synthesis of the gun has the limit up to the ‘throw’ of the gun (beam-waist position) and not beyond to predict the shape of the electrodes. He jokingly replied that if he could synthesize the shapes of the gun electrodes he would sell the approach of synthesis in market rather than publish it in a journal. Dr. Vaughan said that as Editor of IEEE Transactions on Electron Devices, as he was then holding the position of, he would like to publish relevant works if I had written. In fact, by then we had already synthesised the electrode shapes by conformal mapping. The inspiration of Dr. Vaughan led us to publish two papers in quick succession: (i) U. Tiwari and B. N. Basu, “Non-iterative synthesis of convergent Pierce electron guns,” IEEE Trans. Electron Devices, Vol.35, pp. 1184-1187 (1988) and (ii) U. Tiwari and B. N. Basu, “Non-iterative method for the synthesis of convergent Pierce electron guns,” IEEE Trans. Electron Devices, Vol.34, pp. 1218-1221 (1987). A brief stay of Dr. Vaughan at CEERI, Pilani left a permanent spell over all of us!

Professor Gun-Sik Park

Professor Gun-Sik Park, Director, Center for THz-Driven Biomedical Systems (CTDBS), Seoul National University (SNU) and Professor, Department of Physics and Astronomy, SNU, has been associated with me in our research endeavours of mutual interest for more than two decades. That I visited his laboratory as many as five times on his invitation is indicative of how he trusts on me. We evidenced our collaboration in our joint publications of research papers. Professor Park worked with me and Dr. S.N. Joshi of CSIR-Central Electronics Engineering Research Institute (CEERI) in establishing an MOU between SNU, Seoul and CSIR, India. Well known to us for his early work on gyro-devices at University of Maryland, Professor Park has been now working in several areas to fulfil the aims and objectives of CTDBS encompassing such area as of interest to our vacuum electron devices community, such as high-power THz wave generation through coherent Cherenkov radiation based on a plasma dielectric wake-field accelerator; high current field emitter using hydrothermally prepared reduced graphene oxide-free standing film; enhanced radiation using Cherenkov effect in fano-metamerical; CNT cathode; klystron for medical LINAC, and so on. I am witness to the relentless effort of Professor Park in developing his laboratory brick by brick from scratch. Professor Park, who hosted and chaired two times IEEE-IVEC at Seoul in 2003 and 2019, respectively, is the pride of Asians working in the area of vacuum electronic devices for his immense contribution to the area.

Professor Samir Kumar Lahiri

Professor Samir Kumar Lahiri, who was Professor and Deputy Director, Indian Institute of Technology (IIT), Kharagpur and who played a key role in establishing Microelectronics Centre at IIT-Kharagpur under the guidance of Professor N.B. Chakraborty, helped me a lot in my research career. I have the proud privilege of being one of his M. Tech classmates at Institute of Radiophysics and Electronics, Calcutta University. Credit goes to one of my best friends, Professor Lahiri, for creating the facilities for wafer processing and mask-making; fabricating “telecard” chip, I2L gate array and a VCO chip for pressure sensors, and using microwave plasma techniques for VLSI processing, and so on, at Microelectronics Centre in IIT-Kharagpur. That Professor Lahiri would become one day an excellent teacher became evident from his success in making the mediocre classmate like me to develop the concepts in various fundamentals of electronics and communication engineering at Institute of Radiophysics and Electronics, Calcutta University. One can access to his brilliant lectures in the area of microelectronics available in Internet. An accomplished artist Professor Lahiri affectionately chose to draw all the figures embodied in my Ph. D thesis, at the time when no modern tools were available. My thesis preserves those figures as my treasure!

Professor Zhaoyun Duan

Professor Zhaoyun Duan, who is Professor of Electronics and Deputy Dean of School of Electronic Science and Engineering at University of Electronic Science and Technology of China (UESTC), Chengdu, is one of my best wishers. Professor Duan is known to the global vacuum electron devices (VED) community not only for his immense contribution in conventional VEDs such as for his remarkable attainment of ~40 MW power at 36.6 GHz from a sheet-beam backward-wave oscillator but also for his breakthrough contribution in metamaterial inspired VEDs such as his development of new MTM-inspired VEDS based on reversed Cherenkov radiation. I came in contact with Professor Duan in 2006 through email interaction in the area of travelling-wave tubes. As a result, he and his colleagues at UESTC co-authored with me, while I was myself in India, a research paper: Z. Duan, Y. Gong, W. Wang, B. N. Basu and Y. Wei, “Accurate tape analysis of the attenuator-coated helical slow-wave structure,” IEEE Trans. Electron Devices, vol. 53, pp. 903-909 (2006)¾interestingly, without Professor Duan having been face to face ever with me. We met each other for the first time five years later at Bangalore, India in the conference IEEE-IVEC-2011. Subsequently, later in 2018, Professor Duan met me at UESTC which I visited on his invitation to deliver a series of lectures to students in the area of VEDs. Professor Duan documented our recent interactions in research papers: (i) Shifeng Li, Zhaoyun Duan, Hua Huang, B. N. Basu, Fei Wang, Zhenbang Liu, Hu He, Xin Wang, Zhanliang Wang, and Yubin Gong, “Input and output couplers for an oversized coaxial relativistic klystron amplifier at Ka band,” IEEE Trans. Electron Devices, vol. 66, pp. 2758-2763 (2019); (ii) Xin Wang, Z. Duan, Xirui Zhan, Fei Wang, Shifeng Li, Shengkun Jiang, Zhanliang Wang, Yubin Gong, , and B. N. Basu, “Characterization of metamaterial slow-wave structure loaded with complementary electric split-ring resonators,” IEEE Trans. Microwave Theory and Technique, vol. 67, pp. 2238-2246 (2019); and (iii) Z. Duan, M. A. Shapiro, Edl Schamiloglu, N. Behdad, Y. Gong, J. H. Booske, B. N. Basu, and R. J. Temkin, “Metamaterial-inspired vacuum electron devices and accelerators,” IEEE Trans. Electron Devices, vol. 66, pp. 207-218 (2019). I regard Professor Duan for his affectionate support to my research endeavour.

Professor Akhlesh Lakhtakia

Professor Akhlesh Lakhtakia of Department of Engineering Science and Mechanics Pennsylvania State University, the great scientist we the Indians are all proud of, who was a B. Tech student of Electronics Engineering Department of Banaras Hindu University (BHU), Varanasi (now known as Indian Institute of Technology-BHU), had already passed out from BHU when I joined the Department of the University as one of its faculty members. However, I met Professor Lakhtakia a number of times during his visits to BHU, Varanasi from Pennsylvania. His B. Tech classmate Professor P.K. Jain was a my fellow faculty member, and, in one of his visits, Professor Lakhtakia found on the desk of Professor Jain the type-written manuscript of a book written by me (not published then). Professor Lakhtakia considered the manuscript to be worth publishing and recommended it to the publishers, and thus the book saw the light of day: B. N. Basu, “Electromagnetic theory and applications in beam-wave electronics,” World Scientific Publishing Co. Inc., Singapore, New Jersey, London, Hong Kong (1996). It was again the recommendation of Professor Lakhtakia that led to the publication of our recent book in two volumes: Vishal Kesari and B. N. Basu, High power microwave tubes: basics and trends, Volume 1 and Volume 2, Morgan and Claypool Publishers, San Rafael (California)/Bristol: IOP Publishing (2018). I am fortunate to receive throughout my academic and research pursuits the affectionate support from Professor Lakhtakia, who is globally known for his inventions in the areas of the complex materials, metamaterials, thin films (sculptured), carbon nanotubes, nano-engineering, biomimetics, forensic science, negative refraction, and so on.

Professor P.K. Jain

Professor P.K. Jain, who is now the Director of National Institute of Technology, Patna, on deputation from Electronics Engineering Department, IIT-BHU (Banaras Hindu University), Varanasi, was my colleague at IIT-BHU (formerly known as IT-BHU) when I joined the Department in 1982. Professor Jain worked with me, before my retirement from the University, in academics and research in the area of vacuum electronic devices at Centre of Research in Microwave Tubes (CRMT). We jointly executed sponsored projects; organized national conferences and short-term courses; supervised B. Tech, M. Tech and Ph. D students in research; and documented our work in journals and monographs. Professor Jain was the key motivating force behind writing my book “Electromagnetic theory and applications in beam-wave electronics,” World Scientific Publishing Co. Inc., and I profoundly acknowledged him in the ‘Dedication’ and ‘Special Acknowledgment’ page of the book. I remember how Professor Jain praised the simplicity of my writing Chapter 7 of the book on magnetic focusing structures for the confinement of an electron beam and thus greatly inspired me. He also motivated me to work hard to include the deduction of the dispersion relation of the gyro-TWT in Chapter 8 of the book with a view to enhancing the value of the book; in fact, before he had included my deduction in the book, he along with his erstwhile B. Tech project student Dr. S.J. Rao, as well as Professor A.J. Sangster of Heriot Watt University, Edinburgh cross-checked this deduction. I owe to Professor Jain for his great support to me throughout my modest research efforts as well as for his immense help in getting me settled at Varanasi.