In this paper, an object characterization method based on neural networks is developed for GPR subsurface imaging. Currently, most existing studies demonstrate detecting and imaging objects of cylindrical shapes. While in this paper, no restriction is imposed on the object shape. Three neural network algorithms are exploited to characterize different types of object signatures, including object...

To compare the measured and the simulated radio frequency Bt distribution in cylindrical phantoms and in the head of healthy volunteers at 128 MHz. The experimental data were obtained with a 3 Tesla MRI research system equipped with a blrdcage coil. The simulated data were obtained with the Finite Difference Time Domain (FDTD) method of calculation for electromagnetics. MATERIAL AND METHODS the...

A thin-film grating on a curved substrate functions as a highly reflective and wavelength sensitive mirror for a diverging wave that has the same curvature as the substrate. In this paper we propose a cylindrical cavity surrounded by a curved resonant grating wall, and describe its resonance characteristics. Through finite-difference time-domain (FDTD) simulation we have clarified that this typ...

This paper presents the results of 3D FDTD modeling of a 915-MHz cylindrical structure with the TM01l mode excited by a coaxial line and intended for thermal processing of a spherical load (a fruit). Energy coupling is shown to be insensitive to the fruit’s type and temperature, but dependent on its size and location and the loop’s radius. The patterns of dissipated power are analyzed from the ...

Dielectric reflectors that are periodic in one or two dimensions, also known as 1D and 2D photonic crystals, have been widely studied for many potential applications due to the presence of wavelength-tunable photonic bandgaps. However, the unique optical behavior of photonic crystals is based on theoretical models of perfect analogues. Little is known about the practical effects of dielectric i...

This paper presents a new whole-body averaged specific absorption rate (SAR) estimation method based on the cylindrical fields scanning technique. The aim of this study is to achieve experimentally an estimation of whole-body averaged SAR in human models due to plane wave exposure using the radiation-field scanning technique. In this paper, the validity of the proposed methods is investigated u...

In this paper, the authors present a new and robust conformal Finite Difference Time Domain (FDTD) algorithm for the accurate modeling of perfectly conducting objects with curved surfaces and edges. We illustrate the application of this approach by analyzing a number of representative antenna and cavity problems. These include a quarter wave monopole mounted on a perfectly conducting elliptic d...

The Finite-Difference Time-Domain (FDTD) method was applied in order to analyze the transient responses of geoelectrical soundings that use circular electric dipole (CED) as source over stratified formations. The model was developed in cylindrical coordinates and a perfectly matched layer (PML) was incorporated to the domain to absorb wave reflections at computational grid boundaries. Numeric r...

Brazilian Microwave and Optoelectronics Society-SBMO received 11 May 2012; for review 18 May 2012; accepted 20 Aug 2012 Brazilian Society of Electromagnetism-SBMag © 2012 SBMO/SBMag ISSN 2179-1074 Abstract — Design and analysis of a 35 GHz metal photonic band gap (PBG) resonant cavity operating in the TE041-like mode has been presented. The dispersion characteristics of a 2D metal PBG structure...

We demonstrate on-chip, single-mode, waveguiding of light in air for a variety of 2D-3D photonic band gap (PBG) heterostructures. These include square spiral, woodpile, slanted pore, and inverse opal three-dimensional (3D) photonic crystals intercalated with a 2D (planar) photonic crystal microchip. Design rules are established to yield maximal single-mode waveguiding bandwidths of up to roughl...