A Miniaturized Polarization-Insensitive Reconfigurable Intelligent Surface for Beam Steering Applications

Reconfigurable intelligent surfaces (RISs) have assumed an important role in the development of the backbone of new communication standards. Their ability to dynamically cause a change in the propagation characteristics of the incoming signal, coupled with their small size and inexpensive nature, has led to their accelerated adoption across the new-age network infrastructure for purposes such as establishing a secure link between the source and the receiver, dynamic switching to the least path-loss transmission path, and so on. The key concerns in designing an RIS that caters to the different applications are polarization-insensitivity and angular stability with respect to the transverse electric (TE) and transverse magnetic (TM) polarized signals. In this work, a miniaturized RIS design is presented for phase switching which is not only polarization-insensitive, but also achieves angular stability for both TE and TM polarized signals. A wide phase switching is obtained (−160° to +160°) by using varactor diodes, as well as high angular stability is achieved up to 50° with an operating frequency centered at 3.5 GHz. The full wave simulation results are presented and corroborated with the equivalent circuit model (ECM) response. It is hoped that this design would lead to the development of more robust and practical RIS structures for beam-steering applications.