Observation of off-axis directional beaming via subwavelength asymmetric metallic gratings

It is possible to obtain enhanced and directional beams using subwavelength metallic structures. However, the enhanced beams throughout such structures are only directed towards the propagation direction. In this study, we design the output surface gratings asymmetrically in order to steer the beaming angle. We use a metallic structure with a subwavelength slit (λ/10) and grating periods of 14 mm and 22 mm on different sides of the output surface. We demonstrate off-axis directional beaming in the microwave regime with an FWHM of 10 deg. with a beaming angle of 15 deg. The beaming angle can be changed by arranging the grating periods of the output surface of the metallic structure.