Ultrawide Bandwidth Electromagnetic Wave Absorbers Composed of Double-Layer Frequency Selective Surfaces with...

Area of Science:

• Electromagnetics
• Materials Science
• Microwave Engineering

Background:

• Microwave absorbers are crucial for reducing unwanted electromagnetic reflections.
• Existing absorbers often face trade-offs between bandwidth, thickness, and performance.
• Frequency Selective Surfaces (FSSs) offer tunable electromagnetic responses.

Purpose of the Study:

• To design and validate a novel, ultra-wide bandwidth, and thin microwave absorber.
• To explore the resonant properties of different FSS unit cell structures.
• To optimize the combination of FSS elements for enhanced absorption performance.

Main Methods:

• Utilized two frequency selective surfaces (FSSs) with distinct resonant frequencies.
• Determined circuit parameters (inductance, capacitance) using equivalent circuit and strip wire conductor models.
• Optimized the FSS combination and validated through simulation and screen-printed sample measurements.

Main Results:

• Achieved an ultra-wide absorption bandwidth from 6.3 GHz to 40.0 GHz (for -10 dB reflection loss).
• Designed a thin absorber with a total thickness of 5.5 mm, approaching theoretical limits.
• Experimental results closely matched simulation predictions, confirming the design's validity.

Conclusions:

• The proposed FSS-based design enables effective ultra-wideband microwave absorption with minimal thickness.
• The design method, based on circuit parameter analysis, is validated.
• Further control of unit cell periodicity is recommended for mitigating grating lobes, especially at oblique angles.