Dielectric structure design for microwave cloaking considering material properties

Abstract

To hide a metallic object from outside observers, we designed cloaking structures to manipulate the propagation path of the microwave at a specific frequency. Dielectric materials are used to realize the cloaking effect and their electromagnetic properties are evaluated to reduce the size of the cloaking structure as well as to take the loss effect into account. We used the structural design method based on the phase field method to control the electric field flow around a target object for cloaking. It is aimed to minimize the scattered electric field measured at the region located behind the target object for a normal incident wave in the X-band frequency range. Numerical examples are given to verify the suggested design process and its results.

A level-set-based topology optimisation for acoustic–elastic coupled problems with a fast BEM–FEM solver

“…After a pioneering work in [5], the topology optimisation is intensively studied mainly in the field of structural mechanics in order to design light but stiff structural members [5,40,45]. Recently, one of the main interests in the topology optimisation community is to widen the applicability of the topology optimisation to problems in various engineering fields other than structural mechanics, such as thermal problems [44,23,29], fluid problems [42,36,43], elastodynamic problems [22,39,32], electromagnetic wave problems [47,2,27,20,17], and so on. There are also many efforts to extend the topology optimisation into various design problems in acoustics such as an acoustic horn to maximise sound level [41], an acoustic metamaterial which realises a material with negative effective bulk modulus [30], and a poroelastic soundproofing material [28,46].…”

Towards Printable Natural Dielectric Cloaks via Inverse Scattering Techniques

“…These approaches, although very attractive in terms of simplicity of the geometrical architecture of the covers, require very large refractive indexes 11,12 , rarely available in nature, or even near-zero dielectric constants 13 , moreover they achieve only nearly optimal performance in terms of residual scattering radiation 14 . Another optimization approach based on the phase field method has been recently proposed 15 for cloaking metallic cylinder, by considering six angular directions of the incident wave. Finally, graded refractive index structures have been proposed for surface cloaking 16,17 .…”

“…Moreover they achieve only nearly optimal performance in terms of residual scattering radiation 14 . Another optimization approach based on the phase field method has been recently proposed 15 for cloaking metallic cylinder, by considering six different angular directions of the incoming wave. Finally, graded refractive index structures have been proposed for surface cloaking 16 , 17 .…”

Optimal design of electromagnetic cloaks with multiple dielectric materials by topology optimization

“…On the other hand, a topology optimization method that realizes cloaking by placing a simple isotropic material around the object was reported. [15][16][17][18][19][20] Topology optimization methods, 21 the most flexible type of structural optimization method, have been applied in many design problems for electromagnetic devices. Andkjaer and Sigmund applied a density-based topology optimization for the design of an electromagnetic cloak made of a single-property dielectric material.…”

“…19 Heo and Yoo proposed a design method for microwave cloaking considering multiple directions using a density-based phase filed method for the topology optimization. 20 Although grayscales are restricted near the interfaces in these density-based approaches, perfectly clear boundaries are not obtained. That is, the optimal configurations are obtained based on the assumption that intermediate materials exist.…”