Jaime Esteban received the Ingeniero de Telecomunicación and Dr. Eng. degrees from the Universidad Politécnica de Madrid, Spain, in 1987 and 1990, respectively. From 1988 to 2014 he was with the Departamento de Electromagnetismo y Teoría de Circuitos, Universidad Politécnica de Madrid. Since 2014 he is with the Departamento de Señales, Sistemas y Radiocomunicaciones of the same University, where he became Full Profesor in 2017. His research interests include the analysis and characterization of waveguides, transmission lines, planar structures and periodic structures, the analysis and design of microwave and millimeter-wave passive devices, and numerical optimization techniques. Dr. Esteban was the recipient of a Spanish Ministry of Education and Science scholarship (1988-1990).