A Study of Electromagnetic Absorbers and Cloaks for the Reduction of Electromagnetic Scattering

Open Access
Author:
Zhou, Yuda
Graduate Program:
Electrical Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
May 21, 2015
Committee Members:
  • Raj Mittra, Dissertation Advisor
  • Julio Urbina, Committee Chair
  • Ram Mohan Narayanan, Committee Member
  • Michael T Lanagan, Special Member
Keywords:
  • absorber
  • frequency selective surface
  • electromagnetic scattering
  • antenna
  • transformation optics
  • field transformation
Abstract:
Electromagnetic absorbers and scattering reduction techniques have long been investigated to discover better performing configurations and exploited to reduce Radar Cross-Section, act as sensors or reduce obstruction effects, throughout the electromagnetic spectrum ranging from UHF to terahertz frequencies, and even at infrared and optical wavelengths. This dissertation presents the research on a novel interpretation and design strategy for designing absorbers based on periodic structures and introduces an algorithm for determining the optimal material parameter for layered absorbers that are wrapped around real-world objects with structural perturbations from a planar surface, which traditional research focuses on almost exclusively. A brief history of absorbers was given and legacy configurations of absorbers were introduced in the first place. Secondly, novel Frequency Selective Surface (FSS)-based absorbers were proposed based on the interpretation of the reciprocity theorem for antenna systems. FSS-based absorbers and were incorporate into layered absorbers as composites for tailored absorption specifications. A comparison of performances was given to serve as a general rule of thumb to select optimal configuration for tailored specifications. This dissertation investigates a nascent solution to the scattering reduction problem, namely cloaking based on the physics of Transformation Optics (TO) and presents the real-world limitations of such solutions. This dissertation proposes an alternative algorithm for developing the optimal material parameter for a physical object in a real-world scenario. These explorations show the great promise and applicability of a comprehensive tailored absorber design strategy on a case-by-case basis.