RIS for Signal Cancellation in 3D

We present a novel application of Reconfigurable Intelligent Surfaces (RIS) for signal cancellation, with particular focus on eliminating radio frequency interference (RFI) cancellation in Radio Astronomy Services (RAS). While existing RIS applications focus on directing reflected electromagnetic (EM) waves to either enhance or null the wave-front, our work cancels RFI by adaptive redirection of EM waves in a three-dimensional space. RAS plays a crucial role in the exploration and understanding of the universe by detecting and analyzing radio emissions from celestial bodies. However, RFI emanating from human-made sources weakens the faint astronomical signals and affect astronomical observations. To address this challenge, we outline 3D RFI cancellation system by a novel RIS design to jointly control the phase and amplitude in specific Directions of Reflection (DoR) to comprehensively cancel any incident RFI on the telescope. We provide a blueprint, supported by analysis, for prototyping such an RIS array and evaluate its performance in a practical setting for multiple Direction of Arrival (DoA). Our results indicate that the RFI from Automatic Dependent Surveillance-Broadcast (ADS-B) from aircrafts can be fully canceled with a relative cancellation error of 1.0181x10(-4).