Wideband-Switchable Metamaterial Absorber Using Injected Liquid Metal.

Area of Science:

• Electromagnetics and Metamaterials
• Microwave Engineering
• Materials Science

Background:

• Metamaterial absorbers offer thin, light, and cost-effective solutions for radar-cross-section (RCS) reduction.
• However, traditional resonant metamaterial absorbers suffer from narrow bandwidth, limiting their practical radar applications.
• Wideband absorbers are crucial for effective RCS reduction across diverse frequency ranges.

Purpose of the Study:

• To propose and demonstrate a wideband-switchable metamaterial absorber utilizing liquid metal for tunable frequency absorption.
• To achieve RCS reduction in both C-band and X-band frequencies using a switchable Jerusalem cross (JC) resonator.
• To overcome the narrow bandwidth limitation of conventional metamaterial absorbers.

Main Methods:

• Design of a switchable JC resonator incorporating slotted circular rings, chip resistors, and microfluidic channels etched on flexible printed circuit board (FPCB) and polydimethylsiloxane (PDMS).
• Integration of liquid metal alloy (eutectic gallium indium - EGaIn) within microfluidic channels to enable frequency band switching.
• Validation through full-wave simulation and experimental measurements of prototype absorbers.

Main Results:

• The proposed metamaterial absorber demonstrated absorption ratios exceeding 90% over specific frequency ranges.
• With empty channels, absorption was observed from 7.43 GHz to 14.34 GHz (covering X-band and part of Ku-band).
• With liquid metal-filled channels, absorption occurred from 5.62 GHz to 7.3 GHz (covering C-band).

Conclusions:

• The liquid metal-based metamaterial absorber successfully achieved switchable absorption bands between C-band and X-band.
• This demonstrates a viable approach for developing tunable, wideband absorbers for advanced radar applications.
• The thin, light, and potentially low-cost design offers significant advantages for RCS reduction.