Abstract: A scanning antenna with an antenna element having an evanescent coupling portion includes a waveguide assembly including a transmission line, adjacent the coupling portion, through which an electromagnetic signal is transmitted, permitting evanescent coupling of the signal between the transmission line and the antenna element. First and second conductive waveguide plates, on opposite sides of the transmission line, define planes that are substantially parallel to the axis of the transmission line, each plate extending distally from a proximal end adjacent the antenna element, whereby the propagated signal forms a beam that is confined to the space between the plates and thus limited to a plane that is parallel to the planes defined by the plates. The signal coupled between the transmission line and the antenna element is preferably polarized so that its electric field component is in a plane parallel to the planes defined by the plates.

Abstract: A waveguide includes a dielectric substrate having first and second opposed surfaces defining a longitudinal wave propagation path therebetween; and a conductive grid on the first surface of the substrate and comprising a plurality of substantially parallel metal strips, each defining an axis. The grid renders the first surface of the substrate opaque to a longitudinal electromagnetic wave propagating along the longitudinal wave propagation path and polarized in a direction substantially parallel to the axes of the strips. The grid allows the first surface of the substrate to be transparent to a transverse electromagnetic wave having a transverse propagation path that intersects the first and second surfaces of the substrate and having a polarization in a direction substantially normal to the plurality of metal strips. A diffraction grating on the second surface allows the waveguide to function as an antenna element that may be employed in a beam-steering antenna system.