A broadband polarization-insensitive cloak based on mode conversion

Abstract

In this work, we demonstrate an one-dimensional cloak consisting of parallel-plated waveguide with two slabs of gradient index metamaterials attached to its metallic walls. In it objects are hidden without limitation of polarizations, and good performance is observed for a broadband of frequencies. The experiments at microwave frequencies are carried out, supporting the theoretical results very well. The essential principle behind the proposed cloaking device is based on mode conversion, which provides a new strategy to manipulate wave propagation.

Broadband mode conversion via gradient index metamaterials

“…In view of this configuration, the index profiles of GIMs in ref. 14 is a special case with g 1 = g 2 = 1.…”

“…In particular, metasurfaces based on gradient index metamaterials (GIMs) have been proposed to completely convert propagating waves into surface-like waves 12 . Waveguides with symmetric GIMs can convert the propagating mode (PM) gradually into surface-like mode (SM) with negligible scattering, achieving asymmetric propagation and waveguide cloaking for a broadband of frequencies independent of the polarization of the incident wave 13 14 . It is therefore desirable to utilize GIMs to design a waveguide structure for mode conversion with suppressed backscattering and high mode conversion efficiency.…”

Applications of gradient index metamaterials in waveguides

“…More importantly, our proposed devices can work for a broadband of frequencies and are independent of polarizations. Recently, we have implemented a cloaking waveguide structure using similar technique 30 . We are expecting that, based on this new method of manipulating waveguide modes, it could bring about some new applications ( e.g., on-chip routing of light), and more experiments on this topic could be performed.…”

Scattering and Coupling Reduction of Dipole Antenna Using Gradient Index Metamaterial Based Cloak

“…In an earlier work, we demonstrated the use of gradient index metamaterial for cloaking wherein the scattering due to a PEC cylinder was suppressed by enclosing it with conformal GIM based shell with spatially varying permittivity ( ) and permeability (μ) profiles [16]. The cloaking behaviour was attributed to the mechanism of conversion of propagating waves into surface waves and vice-versa [16][17][18][19]. To achieve this, the GIM based cover was designed by arranging supercells with spatially varying and/or μ profiles around the object in such a way that as the EM wave reaches the cover, it gets converted to surface waves and again back to propagating waves while leaving the cloak.…”