# Broadband impedance matching for lossy magnetic metamaterials in conductive media

## TL;DR

This paper introduces a new model for broadband impedance matching in lossy magnetic metamaterials used in conductive environments like water.

## Contribution

The novel broadband impedance matching model enables efficient transducer design for lossy magnetoinductive waveguides in conductive media.

## Key findings

- A transducer designed using the model achieved a 15.5% fractional bandwidth in an ocean water phantom.
- The model demonstrated a maximum reflection coefficient of −9.0 dB in the propagation band of the waveguide.
- The model allows for MIW applications in complex environments such as underwater or on the human body.

## Abstract

We present a broadband impedance matching model for traveling waves on lossy magnetic metamaterials known as magnetoinductive waveguides (MIWs) in conductive media. Thus far, broadband impedance matching has only been demonstrated in the case of a lossless MIW in free-space due to complexities introduced by losses and eddy current effects. As such, current studies in conductive environments have been limited to utilizing narrow-band matching techniques or relying on attenuation to mitigate reflections, thus limiting the system performance in terms of bandwidth and transmission loss. The proposed model overcomes these limitations by utilizing the nearest neighbor coupling and binomial approximations to generate transducer design criteria in terms of equivalent circuit parameters for broadband impedance matching. To validate the model, a transducer is designed for a 40-MHz lossy MIW submerged in an ocean water phantom. Reflection coefficient results demonstrate a 15.5% fractional bandwidth and a maximum value of − 9.0 dB in the propagation band of the MIW, indicating excellent performance. This model expands the potential design space of MIWs to include complex environments such as underwater, underground, or on the human body.