# A 1-bit electrically reconfigurable metasurface stirrer (ERMS) for improved reverberation chambers

## TL;DR

A new reconfigurable metasurface stirrer improves reverberation chambers by lowering usable frequency and increasing working volume without moving parts.

## Contribution

The novel 1-bit electrically reconfigurable metasurface stirrer (ERMS) enables improved performance in reverberation chambers.

## Key findings

- The ERMS lowers the lowest usable frequency by 95 MHz compared to traditional stirrers.
- The working volume of the chamber increases nearly threefold with the ERMS.
- The ERMS provides a low standard deviation of fields, improving testing accuracy.

## Abstract

We propose an innovative electrically reconfigurable metasurface stirrer (ERMS) designed to significantly enhance the performance of reverberation chambers (RCs). Our proposed ERMS overcomes the limitations of traditional mechanical stirrers or paddles, such as reduced working volume and high lowest usable frequency (LUF). This is achieved by employing a novel metasurface integrated with varactor diodes, which manipulate the stirrer’s reflection phase without any mechanical movement. The fabricated ERMS consists of 88 metasurface unit cells, which measures 2.4 λ × 3.3 λ × 0.122 λ at 600 MHz. Compared to a conventional mechanical stirrer, the ERMS lowered the LUF by 95 MHz (from 420 MHz to 325 MHz), and the working volume increased by nearly three times (from 0.68 m³ to 1.94 m³), thanks to its superior field-stirring characteristics and low-profile planar design. Measurement results confirm that the ERMS significantly improves the capability of RCs, exhibiting an acceptably low standard deviation of fields. This achievement enables more accurate and efficient testing of antennas and wireless communication devices.

The online version contains supplementary material available at 10.1038/s41598-025-29555-5.