# Serrodyne frequency translation using time-modulated metasurfaces

## TL;DR

This paper demonstrates a transparent, time-modulated metasurface at X-band frequencies that achieves serrodyne frequency translation through electrical tuning and cascaded configurations, enabling non-reciprocal signal processing.

## Contribution

It introduces a novel, simple biasing metasurface design that performs frequency translation using a sawtooth modulation waveform, advancing non-reciprocal metamaterial applications.

## Key findings

- Achieved 360° tunable transmission phase
- Demonstrated Doppler-like frequency translation
- Enabled cascaded metasurfaces for phase and amplitude non-reciprocity

## Abstract

Temporally modulated metamaterials have attracted significant attention recently due to their non-reciprocal and frequency converting properties. Here, a transparent, time-modulated metasurface that functions as a serrodyne frequency translator, is reported at X-band frequencies. With a simple biasing architecture, the metasurface provides electrically-tunable transmission phase that covers $360^\circ$. A sawtooth waveform is used to modulate the metasurface, allowing Doppler-like frequency translation. Two such metasurfaces can be cascaded together to achieve magnetless devices that perform either phase or amplitude non-reciprocity.