  Reconfigurable intelligent surface (RIS) is a promising solution to boost
coverage sustainably by reflecting waves from a transmitter to a receiver and
acting as a low-power and passive relay. In this paper, for the first time, we
demonstrate experimentally that a reconfigurable intelligent surface designed
for sub6GHz, and using varactor technology, can perform three-dimensional
reflective beamforming. This result is achieved with a RIS prototype of 984
unit-cells, thanks to a compact control circuit individually addressing and
configuring the voltage of each unit-cell, with a distinct voltage. To our
knowledge, this prototype configures 17 to 70 times more distinct voltages than
in the state-of-the-art. The experimental results in an indoor environment show
a 10 dB gain. They also show, for the first time, that producing such a new
prototype is feasible with minimal energy footprint and environmental impact,
thanks to refurbishing. Indeed, a reflectarray antenna originally designed for
three-dimensional beamforming has been turned into a RIS.
