Solving the Gain/Coverage Problem to enable 5G-Powered IoT

Abstract

Mm-wave 5G base-stations are capable of emitting unprecedented EIRPs, necessary to achieve its high data rates. This capability introduces the opportunity to also use this wireless resource to wirelessly power IoT devices. However, the passive recipients of such power densities would need large enough apertures to harvest appropriate power levels to operate, which would naturally limit their angular coverage. In this work, we present an unconventional solution to this problem through the implementation of a passive beamforming network-the Rotman lens-in the receiving mode, as an intermediate element between antenna arrays and rectifiers to enable the surprising combination of high gain and wide angular coverage. The fully-printed, flexible Rotman lens, operating in the mm-wave regime, is equipped with eight antenna ports and six beam ports, selected based on a scalability study. Tested in both planar and bent configurations, the Rotman lens demonstrates a robust, ultra-broadband behavior, with minimum variations in its gain and angular coverage over more than 20 GHz of bandwidth. These structures promise to power the next generation of passive IoT devices at distances exceeding 100 m using 5G base-stations, with the transmission of the full 75 dBm EIRP allowable by the FCC in the 5G/mm-wave bands, thereby enabling the emergence of ultra-low-cost mmIDs for ubiquitous sensing for smart-city and smart-infrastructure applications.