  Reconfigurable intelligent surfaces (RISs) enable reliable low-latency
millimeter wave (mmWave) communication links in cases of a blocked
line-of-sight (LoS) between the base station (BS) and the user equipment (UE),
i.e. a RIS mounted on a wall or the ceiling provides a bypass for the radio
communication link. We present an active RIS with 127 patch antenna elements
arranged in a hexagonal grid for a center frequency of 23.8 GHz. Each RIS
element uses an orthogonal polarization transformation to enable amplification
using a field-effect transistor (FET). The source and drain voltages of each
FET is controlled using two bits. We assume that the coordinates of the UE in
an industrial control scenario are known to the RIS. We measure the received
power on a 2D grid of 60 cm by 100 cm with the RIS working in reflective and
active mode. The results show that the RIS can successfully focus the radio
signal at the desired target points. The half-power beam width is characterized
in axial and radial directions with respect to the RIS position, obtaining a
practical RIS configuration update criterion for a mobile UE. These results
clearly show that RISs are prominent solutions for enabling reliable wireless
communication in indoor industrial scenarios.
