Wide-Angle Ceramic Retroreflective Luneburg Lens Based on quasi-Conformal Transformation Optics for Mm-Wave Indoor Localization

This paper presents a quasi-conformal transformation optics (QCTO) based three-dimensional (3D) retroreflective flattened Luneburg lens for wide-angle millimeter-wave radio-frequency indoor localization. The maximum detection angle and radar cross-section (RCS) are investigated, including an impedance matching layer (IML) between the lens antenna and the free-space environment. The 3D QCTO Luneburg lenses are fabricated in alumina by lithography-based ceramic manufacturing, a 3D printing process. The manufactured structures have a diameter of 29.9 mm (4 lambda(0)), showing a maximum realized gain of 16.51 dBi and beam steering angle of +/- 70 degrees at 40 GHz. The proposed QCTO Luneburg lens with a metallic reflective layer achieves a maximum RCS of -20.05 dBsqm at 40 GHz with a wide-angle response over +/- 37 degrees, while the structure with an IML between the lens and air improves these values to a maximum RCS of -15.78 dBsqm and operating angular response between +/- 50 degrees.

Automated summary

This paper introduces a three-dimensional retroreflective flattened Luneburg lens based on quasi-conformal transformation optics for wide-angle millimeter-wave radio-frequency indoor localization. The lens is fabricated in alumina through lithography-based ceramic manufacturing process, showing high gain and beam steering angle.