mmIDs Enter the 3rd Dimension: A Camera Inspired Broadbeam High-Gain Retrodirective Backscatter Tag

For the first time, the authors propose a mm-Wave (28 GHz) retrodirective backscatter system capable of large coverage in both azimuth and elevation directions. The structure, inspired by optical cameras, features a 3D-lens backed by an array of individual backscattering elements (pixels). First, the concept is presented. Then, the components of the system are described in detail, including the PTFE lens and the backscatter pixels array. Subsequently, the entire system is assembled and its combination of large azimuth/elevation coverage and differential Radar Cross Section (RCS) is measured, demonstrated, and compared to a lens-less system. Finally, the mmID is tested up to a range of 80 m to demonstrate its long-range potential. The mmID displays a −10 dB coverage of 0.736 sr about boresight, improving the angular coverage by 62 %, relative to the state of the art. This approach unlocks the deployment of dense battery-less 5G-connected mmID sensor swarms in smart city environments.