A Millimeter-Wave Hourglass Reflector-Based Switched-Beam Array

The hourglass reflector geometry is investigated as a scalable method for realizing wideband millimeter-wave arrays with elliptical beams that are broad in azimuth and narrow in elevation. Numerical studies of the important geometrical parameters are conducted to show that the reflector surface can significantly increase the beamwidth of the feed in the azimuth plane while decreasing the beamwidth in the elevation plane, achieving a radiation pattern well suited for communications and electronic support. Changes in the directivity of a Gaussian feed aperture and the reflector's f/D ratio are shown to control the spillover sidelobes, cross-polarization, and directivity. Results with multiple beams indicate this geometry can be used to cover a 360° field-of-view in azimuth with only six feeds, in addition to being able to function as a direction finder.