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distances between the key discontinuities in an iterative procedure. In both approaches, an improved channel filter synthesis technique is used to avoid numerical optimization. It uses multimode tuning of channel filter sections and iterative adjustment of filter specifications. It requires no more than 10 min to design and analyze an E-plane diplexer on an Intel Pentium 200 machine. Such design methods can also be adapted to the design of waveguide multiplexers.
Figure 15. Frequency response of diplexer designed with Y-scheme; w dashed line. return loss response for single step transition, solid line. insertion loss response for two step transitionx.
band between the two channel passbands. This is due to the frequency dispersion of desired properties of the common junction. As a result of the dispersion, the guard band cannot be more than 5% of the center frequency of the guard band. Figure 15 shows the computed frequency response a diplexer designed by the Y-scheme. The dashed line shows the return loss response for a single step transition. The performance of the diplexer with two-step transition is better than that with a one-step transition. A comparison between T-junction and bifurcated junction diplexers reveals that for the same synthesis scheme T-junction diplexers can be designed for a wide range of specifications and offer better performance than bifurcated junction diplexers. However, the realizable guard band can be increased and the passband insertion loss can be improved by successive use of both schemes of synthesis. The Y-scheme provides a better geometry for the common junction and the K-scheme fine tunes the design.
IX. CONCLUSIONS
We have discussed in detail various computer aided design methods for waveguide T-junction and bifurcated junction diplexers. Two design schemes have been considered; the Y-scheme and the K-scheme. On one hand, the use of the K-scheme results in a very compact diplexer. On the other hand, the Y-scheme is simple but it takes lot of computer time to search for the right common junction geometry. In the K-scheme, the required computer time is less than the Y-scheme because the designer only needs to change the
ACKNOWLEDGMENTS
The authors express their deep sense of gratitude to L. Mos’pan for assistance in the work and Dr. S. Senkevich for useful discussions. One of the authors, Protap Pramanick, is grateful to the Natural Sciences and the Engineering Research Council of Canada for financial support. The authors are thankful to the anonymous reviewers for their help.
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BIOGRAPHIES
A. A. Kirilenko graduated from the Radiophysics Department of Kharkov University, Ukraine, in 1965. He received the Ph.D. Degree in 1970, the Dr.Sc. degree in 1980, and the Professor of Radiophysics Rank in 1989. He has worked for the Institute of Radiophysics and Electronics of the National Academy of Sciences of Ukraine IRE NASU. since 1969. He has been the Head of the Department of Applied Electromagnetic of the IRE NASU since 1982 and Professor of Kharkov Aerospace University. His research interests include analytical and numerical techniques for electromagnetic simulation, resonance phenomena in waveguides and gratings, spectral theory of open waveguide structures, and general and problemoriented software for microwave CAD. He is a co-author of three books: Con¨olution-Type Matrix Equations in the Diffrac- tion Theory Kiev: Naukova Dumka, 1984.; Resonant Wa¨e Scattering, Vol. 1, Diffraction Gratings Kiev: Naukova Dumka, 1986.; and Resonant Wa¨e Scattering, Vol. 2, Wa¨eguide Dis- continuities Kiev: Naukova Dumka, 1986.. He has published 150 papers and holds eight patents. Anatoly A. Kirilenko is a winner of the State Premium of Ukraine in the Sphere of Science and Technique. Photo not available..
Leonid A. Rud graduated from the Electronics Department of Kharkov Institute of Radioelectronics, Ukraine in 1969. He
received the Ph.D. degree in 1976, and the Dr.Sc degree in 1990.
He has worked for the Institute of Radiophysics and Electronics of the National Academy of Sciences of Ukraine, since 1971. He is now a leading researcher of this Institute. From 1991 to 1995 he was a Professor at the State Technical University of Radioelectronics, Kharkov, Ukraine. His research interest is mathematical modeling and investigation of wave scattering by waveguide discontinuities, spectral theory of open waveguide resonators, software for design and analysis of frequency-selecting microwave systems.
Dr. Rud is a co-author of the book, Resonant Wa¨e Scatter- ing. Vol. 2. Wa¨eguide Discontinuities Kiev, Naukova Dumka, 1986., and has published more than 70 journal articles. He is a winner of the State Premium of Ukraine in the Sphere of Science and Technique. Photo not available..
Vladimir I. Tkachenko graduated from the Radiophysics Department of Kharkov University, Ukraine, in 1973 and received the Ph.D. degree in 1986 from the same university. From 1973 to 1985 he was with the Physics Technical Institute of Low Temperatures of the National Academy of Science of Ukraine, and worked on the theory of superconductive antennas. Since 1981 he has been with the Institute of Radiophysics
116 Kirilenko et al.
and Electronics of the National Academy of Science of Ukraine. He is now a Senior Researcher of this institute and is a Professor of the State Technical University of Radioelectronics, Kharkov. His current research interests are numerical algorithms and software for the design of microwave devices and large modeling systems for waveguide electromagnetics. His SES-04 system for the simulation of passive microwave devices. was nominated as the best software in microwaves electronics in the former Soviet Union in 1991. Dr. Tkachenko has published more than 40 journal papers. Photo not available..
Protap Pramanick obtained the B. Tech.Hons.. degree in Electronics and Electrical Communication Engineering from the Indian Institute of Technology in 1977 and the Ph.D. degree in Microwave Engineering from the Indian Institute of Technology, Kanpur, India in 1982. In 1982 he joined the Department of Electrical Engineering, University of Ottawa,
as a postdoctoral fellow. In 1984, he joined the Canadian Marconi Company, Ottawa, as a senior design specialist in the Avionics Division. In April 1986 he joined Com Dev Limited, Cambridge, Ontario. Since July 1992 he has been working as an associate professor in the Department of Electrical Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Dr. Pramanick holds several patents on filters for cellular radio. He co-edited the book, E-plane Integrated Circuits Artech House, 1987.; and contributed to the books
Topics in Millimeter-Wa¨e Engineering Academic Press, 1988., Microwa¨e Solid State Circuit Design Wiley Interscience, 1988., and Handbook of Microwa¨e Engineering Academic Press, 1994.. He has published extensively on microwave integrated circuits. He is on the editorial review board of IEEE Transac- tion on Microwa¨e Theory and Techniques and the International Journal of Microwa¨e and Millimeter-Wa¨e Computer-Aided En- gineering. Dr. Pramanick is also the CEO of Polar Waves Consulting and a senior member of the IEEE.