subwavelength aperture in an appropriately corrugated metal film [HJ Lezec, Science 297,
820 (2002) SCIEAS 0036-8075]. Good agreement is found between calculations and
experimental data. We show that beaming is due to the formation of electromagnetic surface
resonances and that the beam direction, width, and wavelength at which it occurs can be
selected by tuning geometrical parameters of the structure.