Frequency Selective Surfaces: An Introduction

Frequency selection is an important property for many applications of electromagnetic (EM) waves. Frequency selective surfaces are two-dimensional objects that can transmit, reflect or absorb electromagnetic waves of certain specific frequencies due to the patterns on their surface. We are familiar with many structures which are coloured in natural settings, such as butterfly wings and peacock feathers, where the colour (frequency) selection is not due to the presence of any pigment but due to the periodicity of patterns in them. Frequency selective surfaces are a step ahead of these examples and can be used to make extremely lightweight objects such as planar lenses and the thinnest mode/polarization converters. This article gives a brief description of frequency selective surfaces and some examples of how they work, along with a list of a few of their applications.