Raghuvir Tomar

A Low-Loss Voltage-Controlled Analog Phase-Shifter Using Branchline Coupler and Varactor Diodes

This paper proposes a new type of continuously tunable voltage-controlled analog phase shifter for radio frequency and microwave-frequency applications. The design uses a branchline coupler and two varactor diodes. The concept has been tested at 900 MHz using FR4 dielectric material using thin-film microstrip technology. The measured phase shift variation is 115 degree over the entire range of the control voltage. The measured insertion loss is typically better than 1.5 dB and the measured return loss is better than-15 dB. The performance can be further improved by using lower-loss dielectric materials. The design is also scalable to other frequency bands.

The use of 3D electromagnetic simulation tools in the design of Microwave Integrated Circuits: An accuracy assessment

The accuracy of well-known commercially available 3D electromagnetic simulation tools has been examined through designing, building, and testing several original Microwave Integrated Circuits. It turns out that the accuracy of the tools considered is acceptable for most practical purposes, for frequencies up to 3GHz (upper limit of our investigation).

Microwave Power Amplifiers for Satellite Communication Systems

This paper provides a short review of radio frequency/microwave power amplifiers (PAs) and their critical role in a modern satellite communication system.

Microwave power amplifiers for satellite communication systems

This paper provides a short review of radio frequency/microwave power amplifiers (PAs) and their critical role in a modern satellite communication system.

Design and analysis of low pass microstrip filters using MATLAB

A MATLAB-based CAD algorithm for analyzing stepped-impedance microstrip low-pass filters is reported. The algorithm uses a circuit theory approach based on ABCD parameters of the individual microstrip lines. The accuracy of the algorithm is verified for two widely-different practical examples, against data obtained using the ANSYS/ANSOFT circuit simulation tool and the HFSS simulation tool. The agreement among the three sets of data is found to be quite good. It is concluded that the use of MATLAB is a useful alternative for designing microstrip low-pass filters with stepped-impedance resonators.

The design of reconfigurable antenna arrays using the method of vector space projections

The problem of element failure in antenna arrays is studied using the wellborn method of vector space projections (VSP). The use of VSP allows one to impose a set of desired constraints thru “alternating projections” to furnish a design of self healing arrays i.e. retrieving the sane performance, over the degraded one. By introducing a projection onto the set of dynamic range constraint(DRC), worthy results can be realized even in the case of 50% array element failure.

Microwave High Power Amplifiers for Satellite Communication

Prof. Raghuvir Tomar earned a B.Tech. (Electronics Engineering) from MITS Gwalior in 1975; an M.Tech. (Electrical Engineering) from IIT Kanpur in 1978 and a Ph. D. (Electrical Engineering) also from IIT Kanpur; in1983. Between 1984 and 1986 he carried out research work at post-doctoral level at the University of Ottawa, Canada. His industrial experience includes RF Engineer, Bolriet Technologies, Canada (Sept1986-Aug1988), Member of Scientific Staff, Bell Northern Research, Canada (Aug1988-May1992), Senior Engineer, NORTEL Networks, Canada (May1992-May1999), Senior Systems Engineer, EMS Technologies, Canada (May1999April2003), Visiting Scientist, Communications Research Centre, Canada (May2003-June2004) and Principal Engineer, NATEL Engineering Co., California, USA (June2004-Dec2005). In December 2005 he was appointed Professor at the LNM Institute of Information Technology, Jaipur. His long hands-on experience with microwave and wireless industry including defense industry spans a period of some nineteen years. He has authored more than forty-five research papers (nine in IEEE) and technical reports in peer-reviewed journals and forums of the highest international repute. He co-authored a book on millimeter-wave printed antennas published by Artech House, Massachusetts, USA. A second book titled ‘Fundamentals of Electromagnetic Theory’ is in progress.