# Waveform Selective Surfaces

## TL;DR

This paper introduces a novel microwave surface that selectively transmits or reflects signals based on waveform characteristics, such as pulse width, by integrating nonlinear electronics, enabling advanced control over electromagnetic wave interactions.

## Contribution

It presents the first waveform-selective surface that controls electromagnetic transmission and reflection based on pulse shape, expanding beyond traditional frequency-based selectivity.

## Key findings

- Demonstrated a microwave window with waveform-dependent transmission and reflection.
- Enabled differentiation between short pulses and continuous waves at the same frequency.
- Potential applications in communication, radar, cloaking, and wavefront shaping.

## Abstract

The role of frequency is very important in electromagnetics since it may significantly change how a material interacts with an incident wave if the frequency spectrum varies. Here, we demonstrate a new kind of microwave window that has the unique property of controlling transmission and reflection based not only on the frequency of an incoming wave but also on the waveform or pulse width. This surface can preferentially pass or reject different kinds of signals, such as short pulses or continuous waves, even if they occur at the same frequency. Such a structure can be used, for example, to allow long communication signals to pass through, while rejecting short radar pulses in the same frequency band. It is related to the classic frequency selective surface, but adds the new dimension of waveform selectivity, which is only possible by introducing nonlinear electronics into the surface. Thus, our study is expected to provide new solutions to both fundamental and applied electromagnetic issues ranging from traditional antenna design and wireless communications to emerging areas such as cloaking, perfect lenses, and wavefront shaping.

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Source: https://tomesphere.com/paper/1903.11201