Scanning antenna with beam-forming waveguide structure

A waveguide assembly for a scanning antenna for the transmission and/or reception of an electromagnetic signal having a propagation wavelength λ, the antenna including an antenna element with an evanescent coupling portion the waveguide assembly comprising:

• a transmission line through which an electromagnetic signal is transmitted, wherein the transmission line defines an axis, and wherein the transmission line is located adjacent the evanescent coupling portion of the antenna element so as to permit evanescent coupling of an electromagnetic signal between the transmission line and the antenna element;
• and
• first and second substantially parallel conductive waveguide plates disposed on opposite sides of the transmission line, each of the plates defining a plane that is substantially parallel to the axis defined by the transmission line, each of the plates having a proximal end spaced from the antenna element by a gap of less than λ/2 in width, and a distal end remote from the antenna element, the plates being separated by a distance that is less than λ and greater than λ/2:
• whereby the electromagnetic signal coupled between the transmission line and the antenna element propagates as a beam that is substantially confined to a space defined between the first and second plates, whereby the beam is in a plane that is substantially parallel to the planes defined by the first and second plates.