Joseph Helszajn,, PhD, is an international authority on non-reciprocal microwave circuits and devices. He has made a significant contribution to the characterization of the complex gyrator circuits and gain-bandwidth products of planar gyromagnetic resonators and other gyromagnetic devices. Professor Helszajn is a Fellow of the Institute of Electrical and Electronic Engineers, the City and Guilds Institute, the Royal Society of Edinburgh and the Royal Academy of Engineering. He previously authored thirteen books, nine of which were published by Wiley.