Processes of forming of electromagnetic pulses (EMP) by plane apertures (circle, square and rectangle) and diffusion of EMP in free space are investigated by Kirhgofe-Hyugens method. The picture of EMP evolution is received by numerical methods both in short-range zone (Frenel zone) and in the long-range zone (zone). Formation of EMR of nanosecond scale by open end of waveguide is studied in terms of exact Wienev-Hoft method. The process of diffusion of EMP along impedance (sea) surface is considered. The influence of attenuation of EMP in seawater on pulse form and amplitude is studied.