# Uncorrelated Configurations and Field Uniformity in Reverberation Chambers Stirred by Tunable Metasurfaces

## TL;DR

This paper presents an innovative mode stirring method using tunable metasurfaces in reverberation chambers, significantly increasing uncorrelated field realizations and improving measurement uniformity.

## Contribution

The study introduces a novel electronically reconfigurable metasurface-based stirring technique, enabling more efficient and diverse field configurations within small reverberation chambers.

## Key findings

- High number of uncorrelated field realizations achieved
- Good agreement with random matrix theory model
- Enhanced uniformity criterion performance

## Abstract

Reverberation chambers are currently used to test electromagnetic compatibility as well as to characterize antenna efficiency, wireless devices, and MIMO systems. The related measurements are based on statistical averages and their fluctuations. We introduce a very efficient mode stirring process based on electronically reconfigurable metasurfaces (ERMs). By locally changing the field boundary conditions, the ERMs allow to generate a humongous number of uncorrelated field realizations even within small reverberation chambers. We fully experimentally characterize this stirring process by determining these uncorrelated realizations via the autocorrelation function of the transmissions. The IEC-standard uniformity criterion parameter $\sigma_{dB}$ is also investigated and reveals the performance of this stirring. The effect of short paths on the two presented quantities is identified. We compare the experimental results on the uniformity criterion parameter with a corresponding model based on random matrix theory and find a good agreement, where the only parameter, the modal overlap, is extracted by the quality factor.