Abstract: An antenna array comprises a substrate; a plurality of projecting, tapering structures disposed in an array and attached to a first major surface of said substrate, the plurality of projecting, tapering structures defining a plurality of waveguides therebetween; and a plurality of box-shaped structures disposed in an array and attached to a second major surface of the substrate, the plurality of box-shaped structures defining a plurality of waveguides therebetween, the plurality of waveguides defined by the plurality of projecting, tapering structures aligning with the plurality of waveguides defined by the plurality of box-shaped structures. The substrate includes a plurality of probes for feeding the plurality waveguides.