Bifocal Planar Slotted-Waveguide Antenna Array

A bifocal planar two-layer slotted-waveguide antenna array, consisting of a planar waveguide with one or several feed elements and an array of dielectric-filled rectangular metal waveguides with paired longitudinal slots in their wide walls has been proposed and investigated. The solution of the synthesis problem has shown that the shape of the reflector and coupling slot is elliptic, and it has made it possible to find the positions of the slots in the rectangular waveguides that can ensure the absence of phase aberrations for the two positions of the feed element in the planar waveguide. Using the phenomenological theory of slotted-waveguide arrays and the finite-element method, a numerical simulation of the beam-scanning characteristics for the feed element moved along the focal curve passing through the focuses of the ellipse has been performed. It has been shown that the scan sector of a planar bifocal array of a large electrical size and with an elliptic reflector is considerably larger than for a similar system with a parabolic reflector.