Finite-difference time-domain analyses of active cloaking for electrically-large objects

Area of Science:

• Electromagnetics
• Metamaterials
• Computational Physics

Background:

• Invisibility cloaking requires broadband operation for electrically large objects.
• Active cloaking schemes using surface sources are known but not fully analyzed computationally.
• Previous analyses faced numerical accuracy and computational challenges.

Purpose of the Study:

• To perform detailed time- and frequency-domain analyses of active cloaking devices.
• To investigate the performance characteristics of broadband scattering cancellation for large objects.
• To address numerical limitations in simulating electrically large objects.

Main Methods:

• Utilized a finite-difference time-domain (FDTD) method.
• Implemented a perfect total-field/scattered-field (TFSF) interface for FDTD.
• Achieved high isolation between scattered and total fields (approx. -300 dB).

Main Results:

• Demonstrated accurate evaluation of scattering from imperfect active cloaks.
• Observed scattering suppression at specific frequencies even with time-delayed sources.
• Showcased broadband back-scattering suppression with imperfect sources and predetermination times.

Conclusions:

• Active cloaking performance is sensitive to source switching and predetermination times for omnidirectional suppression.
• The FDTD-TFSF method enables accurate analysis of complex cloaking scenarios.
• This work provides crucial insights for the development of practical broadband invisibility cloaks.