Optimizing broadband microwave absorbers for applications in the 70-200  GHz range.

Area of Science:

• Electromagnetics and Materials Science
• Microwave Engineering
• Metamaterial Research

Background:

• Microwave absorbers are crucial for reducing unwanted electromagnetic reflections.
• Optimizing absorber performance requires understanding the interplay of material, geometry, and scale.
• Previous studies often focused on specific design parameters or frequency ranges.

Purpose of the Study:

• To comprehensively investigate the performance of square-tiled microwave absorbers.
• To determine the relative importance of material properties, frequency, geometry, and unit cell size.
• To identify optimal design principles for high-frequency microwave absorption.

Main Methods:

• Extensive numerical simulations of square-tiled absorber designs.
• Probing performance across a wide frequency range (70-200 GHz).
• Analysis of both specular reflection and total absorption characteristics.

Main Results:

• Absorber scale size relative to wavelength is a critical performance factor.
• Material properties have a less significant impact compared to scale and geometry.
• Achieved 99.5%-99.9% frequency-averaged absorption with specific designs.
• Low specular reflectance does not always correlate with optimal total absorption.
• Exponential, Klopfenstein, and linear impedance tapers show comparable performance with appropriate unit cell size (1-4 mm).

Conclusions:

• Absorber unit cell size is paramount for achieving high absorption efficiency.
• Designers can prioritize scale and geometry over specific material choices for broad frequency absorption.
• Validated simulation results with experimental specular reflectance measurements.