The suprastructure over a substrate integrated waveguide (SIW) can provide for beam scanning utilizing a reconfigurable metasurface. The reconfigurable metasurface will have a plurality of PIN diode arrays that can be turned ON and OFF. In one design, the length of the reconfigurable metasurface is effectively enlarged or reduced in size to achieve beam scanning. In another design the tilt angle of the reconfigurable metasurface is adjusted to achieve beam scanning. The suprastructure also can be modified with metallic offset wings, where two or more pairs of offset wing can form a horn shaped element. The presence of the wings or horn, as well as control of the size and number of the wings can improve the gain of the SIW. These two suprastructure improvements may be used in combination, and they may be used over classical slotted SIWs or over an SIW with curved sections between consecutive slots.