Guest Editorial

The 18 articles in this special issue, designed as a tribute to Professor Leopold B. Felsen, focus on electromagnetic waves in complex environments. Specific topics that are covered include: fundamental electromagnetic wave theory; canonical problems in diffraction theory; ray-based asymptotics; inhomogeneous media; random media; Green´s functions; ray-mode hybrids; complex source points and beams; spectral representations; time-domain techniques and phenomena; phase-space parameterization; inverse scattering and target identification; network and fields; and propagation in and around periodic structures.