Mutual Coupling in Reconfigurable Wave Systems
Philipp del Hougne · 2025
Dynamic metasurface antennas (DMAs), reconfigurable intelligent surface (RISs), and wave-based physical neural network (PNNs) are prominent contemporary examples of reconfigurable wave systems. Due to mutual coupling, their transfer functions depend in general non-linearly on the configuration of their tunable elements. Mutual coupling is hence often mitigated to simplify the configuration optimization. However, this reasoning overlooks that mutual coupling boosts the strength of the transfer function dependence on the tunable elements’ configurations. First, I will present theoretical, numerical, and experimental evidence to demonstrate that the control over a DMA’s radiation pattern substantially increases with the mutual coupling strength. Second, to reap this benefit of mutual coupling, I will pave the way toward in-software model-based optimizations of reconfigurable wave systems. Specifically, I will discuss a universal model-based framework for wave control in reconfigurable wave systems. I will report experimental evidence showing that the "Virtual VNA" method can unambiguously retrieve the model parameters, even for non-reciprocal systems and under limitations to non-coherent detection.