Abstract:This paper proposes a radial dependent dispersive finitedifference time-domain method for the modelling of electromagnetic cloaking structures. The permittivity and permeability of the cloak are mapped to the Drude dispersion model and taken into account in dispersive FDTD simulations. Numerical simulations demonstrate that under ideal conditions, objects placed inside the cloak are 'invisible' to external electromagnetic fields. However for the simplified cloak based on linear transformations, the back scattering has a similar level to the case of a PEC cylinder without any cloak, rendering the object still being 'visible'. It is also demonstrated numerically that the simplified cloak based on high-order transformations can indeed improve the cloaking performance.

No abstract

No abstract

No abstract

Endoscopes formed by arrays of metallic wires can transmit, magnify, and demagnify near-field distributions with subwavelength resolution. Our experiments demonstrate that despite their small apertures, the parallel multiwire endoscopes can be used to transmit near-field distributions with a resolution of five thousandths of a wavelength to a distance of a half-wavelength in the microwave frequency range, and tapered multiwire endoscopes with flat input and output interfaces provide threefold image magnification and demagnification.

In this article, we propose a two‐dimensional indoor localization system using fingerprinting of received optical signals emitted from light emitting diodes (LEDs).The transmitters and receiver are designed and constructed to use visible light as the signal for localization. At the transmitter side, the input voltage/current is modulated with continuous waves before being sent to the LEDs, where each transmitter is assigned with a different frequency. At the receiver side, the power spectral density of the received signal is calculated and the location is estimated as one of the fingerprint locations using a novel but yet simple algorithm. Both the simulation and experiment have been conducted to evaluate the accuracy of the system in a controlled environment. We demonstrate that the system has the potential to estimate locations in the level of centimeters. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1218–1227, 2012

An experimental investigation of subwavelength imaging by a wire medium slab is performed. A complex-shaped near field source is used in order to test imaging performance of the device. It is demonstrated that the ultimate bandwidth of operation of the constructed imaging device is 4.5% that coincides with theoretical predictions [P. A. Belov and M. G. Silveirinha, Phys. Rev. E 73, 056607 (2006)]. Within this band the wire medium slab is capable of transmitting images with λ∕15 resolution irrespective of the shape and complexity of the source. Actual bandwidth of operation for particular near-field sources can be larger than the ultimate value, but it strongly depends on the configuration of the source.

A radial-dependent dispersive finite-difference time-domain (FDTD) method is proposed to simulate electromagnetic cloaking devices. The Drude dispersion model is applied to model the electromagnetic characteristics of the cloaking medium. Both lossless and lossy cloaking materials are examined and their operating bandwidth is also investigated. It is demonstrated that the perfect "invisibility" from electromagnetic cloaks is only available for lossless metamaterials and within an extremely narrow frequency band.