Study of RIS Unit Cells Using 3D-Printed Waveguides

Reconfigurable intelligent surface (RIS) is a promising technology that can increase bandwidth and coverage in modern wireless networks. One way to measure the amplitude and phase response of RIS unit cells (UCs) is through the use of waveguides. However, commercial waveguides have fixed dimensions, making it impossible to measure RIS with arbitrary distance between UCs. This work proposes an alternative approach for measurement using 3D-printed waveguides that match the dimensions of the RIS UCs. The 3D-printed waveguide presented in this work has a standing wave ratio comparable to that of commercial ones. The convergence of the frequency and phase responses obtained from modeling and from measurements using this waveguide demonstrates accuracy and potential of this approach for prototyping RIS with arbitrary distance between UCs.