Abstract: A scalable reconfigurable intelligent surface (RIS) includes a plurality of RIS elements. The RIS elements include: a radio frequency identification (RFID) chip that powers the RIS element; a RFID antenna connected to the RFID chip; a RIS variable impedance controlled by the RFID chip; and a RIS antenna connected to the RIS variable impedance. The plurality of RIS elements produces a reflection beam that may be directed to a specific location. The RFID chip receives steering information to steer the reflection beam.

Abstract: An energy harvesting unit includes a plurality of antennas configured to receive one or more signals and a plurality of first charge pumps, in which each of the first charge pumps is operatively coupled to one of the antennas, thereby forming pairs of antennas and first charge pumps. The energy harvesting unit also includes a selection unit configured to measure and compare output voltages of the first charge pumps and to select, from the antennas, a specific antenna. The specific antenna is coupled to the first charge pump that produces the highest output voltage. The energy harvesting unit also includes a multiplexer configured to couple the specific antenna selected by the selection unit to a second charge pump.