Polarization Insensitive, Wide-Angle, Ultra-wideband, Flexible, Resistively Loaded, Electromagnetic Metamaterial...

Area of Science:

• Electromagnetic metamaterials
• Microwave absorption technologies
• Advanced materials science

Background:

• Metamaterial absorbers are crucial for controlling electromagnetic waves.
• Existing absorbers often struggle with polarization insensitivity, wide angles, and broadband performance.
• The need for flexible and efficient absorbers in diverse applications is growing.

Purpose of the Study:

• To develop a novel, polarization-insensitive, wide-angle, and broadband electromagnetic metamaterial absorber.
• To demonstrate its effectiveness on both flat and curved geometries.
• To enhance frequency bandwidth using inkjet-printed resistive traces.

Main Methods:

• Designed a unit cell comprising four sequentially rotated split ring resonators.
• Utilized low-resistivity copper traces initially, then replaced them with inkjet-printed resistive traces to increase bandwidth.
• Simulated and measured absorption efficiency for various polarizations and incidence angles (0-45 degrees).

Main Results:

• The flat absorber achieved >0.8 absorption efficiency from 6.9-29.9 GHz (125% bandwidth) irrespective of polarization.
• The curved absorber demonstrated bandwidths of 126% (6.6-29 GHz) and 95% (10.5-29.6 GHz) depending on polarization.
• For oblique incidence (0-45 deg), bandwidths of 118% (7.7-29.9 GHz) for TE and 100.5% (9.9-29.9 GHz) for TM polarization were achieved.
• The absorber has a compact thickness of 3.89 mm (λ/11.7 at the lowest frequency).

Conclusions:

• The proposed metamaterial absorber offers excellent polarization-insensitive, wide-angle, and broadband absorption.
• The use of inkjet-printed resistive traces effectively enhances frequency bandwidth.
• The absorber's adaptability to both flat and curved surfaces makes it suitable for various practical applications.