Multipath Signal-Selective Metasurface: Passive Time-Varying Interlocking Mechanism to Vary Spatial Impedance for Signals with the Same Frequency

TL;DR

This paper introduces a passive, time-varying metasurface that adaptively suppresses multipath interference signals at the same frequency by adjusting spatial impedance through a novel interlocking mechanism, validated numerically and experimentally.

Contribution

It proposes a passive, time-varying metasurface design that overcomes LTI limitations to selectively suppress multipath signals at the same frequency.

Findings

Numerical and experimental validation of the metasurface's effectiveness.

Successful suppression of multipath interference signals.

Demonstration of passive, time-varying spatial impedance control.

Abstract

Electromagnetic (EM) multipath interference is difficult to address with passive approaches due to two physical restrictions - the shared frequency of the initial and interfering signals and their variable incident angles. Thus, to address multipath interference, the spatial impedance must be adjusted in response to the incident angles of multiple signals with the same frequency, which is impossible with classic linear time-invariant (LTI) systems. We present a design concept for metasurface-based spatial filters to overcome LTI behavior and suppress multipath interference signals using a time-varying interlocking mechanism without any active biasing systems. The proposed devices are coupled to the first incoming wave to adjust the spatial impedance and suppress delayed waves in the time domain, which is validated numerically and experimentally. This study opens a new avenue for passive yet time-varying selective EM metasystems, enabling the adjustment of spatially complicated EM waves and fields even at the same frequency.