A Broadband Metasurface Absorber Based on Indium-Tin-Oxide Thin Film

This paper presents the design and measurement of a polarization-insensitive broadband metasurface absorber utilizing an indium tin oxide (ITO) resistive film. The metasurface, comprising an ITO conductive layer, effectively absorbs electromagnetic waves by generating ohmic losses, resulting in high absorption. The absorber demonstrates an absorption rate exceeding 90% across a frequency range of $18 \mathbf{~ G H z}$ to 22 $\mathbf{G H z}$, achieving a bandwidth of 4 GHz. The unit cell, with a period length of 0.37 wavelengths, consists of four rotated slotted patches and is polarization-insensitive to incident angles. The overall structure is composed of three layers: an ITO film layer, a PET film layer, and a Rogers RO4350B substrate. The reflection coefficient was measured using the rectangular waveguide method, showing good agreement with simulation results.

I. Introduction

Absorbers, crucial components in reducing radar cross-section and enhancing stealth, have found widespread applications in both military and civilian fields. With the continuous advancement of technology, the demand for improved absorber performance, particularly the ability to maintain high absorption efficiency across a broad frequency range, has been increasing. Traditional absorber designs often rely on metallic structures to achieve electromagnetic resonance. However, these absorbers typically suffer from a significant limitation: they generally exhibit a narrow absorption bandwidth. While metal-based absorbers can achieve high absorption rates within a specific frequency range, their performance drastically declines as the frequency deviates from the center, due to mismatched surface impedance.