An Engineered Half-Eaton Lens Antenna with Amplitude-Only Direction Finding Capability

This paper proposes an engineered half-Eaton lens (EHEL) antenna for full azimuthal coverage with high gain patterns emanating from ports placed in a flat feed plane. Essentially, the lens bends rays entering from the feed plane by 90 degrees, directing them towards horizon. The permittivity profile of the lens is designed using a parametric study described herein, and performance of EHELs with 1–5 lambda radius and with various feeds is reported. An example EHEL fed by monopoles operating over 24–36 GHz is shown. The lens produces 36 high quality directive beams over all azimuth angles at horizon as well as an omnidirectional beam from a feed placed in the center of the lens. Further exemplifying its efficacy, the antenna's amplitude-only direction-finding performance is shown over full azimuth with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{a}+/-20$</tex> degrees field-of-view in elevation.