MEMS Switch Enabled Spatiotemporally Modulated Isolators

TL;DR

This paper presents a MEMS switch-based spatiotemporally modulated isolator for underwater acoustic communication, enabling non-reciprocal filtering and improved self-interference cancellation in the ultrasonic frequency range.

Contribution

It introduces a novel MEMS switch-enabled STM isolator design for underwater acoustics, achieving non-reciprocal filtering at sub-megahertz frequencies.

Findings

Maximum measured isolation of 15.99 dB

Strong agreement between PCB implementation and simulations

Enables in-band full duplex underwater communication

Abstract

This work reports the simulation, design, and implementation of a compact MEMS switch based spatiotemporally modulated (STM) bandpass filtering isolator to improve self-interference cancellation (SIC) in underwater acoustic communication networks. Conventional ferrite circulators are unavailable in ultrasonic frequency ranges limiting SIC to techniques such as spatial cancellation and adaptive digital cancellation. This study details a sub-megahertz electronic non-magnetic filtering isolator. High power-handling, compact, and reliable MEMS switches enable the periodically time varying filter circuit to be non-reciprocal. A printed circuit board (PCB) implementation shows strong agreement with spectral admittance matrix simulations with a maximum measured isolation of 15.99 dB. In conjunction with digital SIC methods, this isolator can enable in-band full duplex underwater communication, environmental sensing, and imaging.