This thesis considers the multi-functionality of the next generation reconfigurable intelligent surfaces (RIS), which are anticipated to play a significant part in sixth-generation (6G) wireless networks. This thesis describes two hardware prototypes developed for 5G frequency range 1 (FR1) and 5G frequency range 2 (FR2) millimetre-wave (mmWave) operation. Hardware implementation details are provided, considering radio-frequency (RF) circuits, localisation algorithms, and printed circuit board (PCB) design. The measurement-based channel model has been developed for these prototypes, considering mutual coupling between unit cells and localisation of user equipment (UE). This channel model has been verified through an extensive measurement campaign at the Institute for Communication Systems (ICS), University of Surrey.