Evolutions towards a new LSPR particle: Nano-sinusoid Progress in Electromagnetic Research (PIER)

This paper proposes a novel nano-sinusoid particle to be employed in enhanced localized surface plasmon resonance (LSPR) bio-sensing devices. Numerical investigations are carried out to demonstrate advantages o®ered by the proposed nano-particle on LSPR enhancement over other nano-particles including noble nano-triangles and nano-diamonds. Although nano-triangles exhibit high concentration of the electric ¯eld near their tips, when illuminated with a light polarized along the tip axis, they present only one hot spot at the vertex along the polarization direction. To create a structure with two hot spots, which is desired in bio-sensing applications, two nano-triangles can be put back-to-back. Therefore, a nano-diamond particle is obtained which exhibits two hot spots and presents higher enhancements than nano-triangles for the same resonant wavelength. The main drawback of the nano-diamonds is the °uctuation in their physical size-plasmon spectrum relationships, due to a high level of singularity as the result of their four sharp tip points. The proposed nano-sinusoid overcomes this disadvantage while maintaining the bene¯ts of having two hot spots and high enhancement

A Surface Admittance Equivalence Principle for Non-Radiating and Cloaking Problems

In this paper, we address non-radiating and cloaking problems exploiting the surface equivalence principle, by imposing at any arbitrary boundary the control of the admittance discontinuity between the overall object (with or without cloak) and the background. After a rigorous demonstration, we apply this model to a non-radiating problem, appealing for anapole modes and metamolecules modeling, and to a cloaking problem, appealing for non-Foster metasurface design. A straightforward analytical condition is obtained for controlling the scattering of a dielectric object over a surface boundary of interest. Previous quasi-static results are confirmed and a general closed-form solution beyond the subwavelength regime is provided. In addition, this formulation can be extended to other wave phenomena once the proper admittance function is defined (thermal, acoustics, elastomechanics, etc.).Comment: 7 page

Closed-form Harmonic Contrast Control with Surface Impedance Coatings for Conductive Objects

The problem of suppressing the scattering from conductive objects is addressed in terms of harmonic contrast reduction. A unique compact closed-form solution for a surface impedance $Z_s(m,kr)$ is found in a straightforward manner and without any approximation as a function of the harmonic index $m$ (scattering mode to suppress) and of the frequency regime $kr$ (product of wavenumber $k$ and radius $r$ of the cloaked system) at any frequency regime. In the quasi-static limit, mantle cloaking is obtained as a particular case for $kr \ll 1$ and $m=0$. In addition, beyond quasi-static regime, impedance coatings for a selected dominant harmonic wave can be designed with proper dispersive behaviour, resulting in improved reduction levels and harmonic filtering capability.Comment: 6 page

Tunable periodic microstrip structure on GaAs wafer

A one dimensional tunable periodic structure in microstip technology on gallium arsenide (GaAs) substrate is numerically investigated. The unit cell contains a number of patches positioned between the ground plane and the microstrip line. The patches, representing reactive loads, can be selectively short-circuited by externally-controlled FET switches integrated in the hosting substrate. The possibility of controlling the position of the band-gap, and implicitly the value of the e®ective dielectric constant along the line, for different combinations of the switches is demonstrate

A Case Study for Improving Performance of Frequency Selective Surface through Union of Sub-Sets and Particle Swarm Optimization

Frequency Selective Surfaces (FSSs) consist of a repetition of a given pattern in a periodic way; typically, a dielectric substrate supports this arrangement giving rise to a two-dimensional array. Although relatively simple in structure, designing an FSS that exhibits large bandwidth and stable response to oblique incidence is not straightforward and requires special attention and significant computational effort. To address this problem, this study presents a methodology whereby an initial configuration of the FSS pattern is subjected to an optimization method for sizing the geometrical parameters. Consequently, the initial unit cell is first broken down into subsections, specifically as a “union of subsets”, then particle swarm optimization is used to achieve optimal design parameters that further improves the overall FSS performances. To validate the proposed method, an X-band FSS is proposed and optimized in a commercial simulation environment (Microwave Studio, Dassault Systèmes)

Multidisciplinary investigations on the use of TiNb alloy orthopedic device equipped with low profile antenna as smart sensor

Abstract In this paper, a new complex medical device is proposed using TiNb based metallic alloy, acting also as a ground plane for a low profile printed antenna sited on a Polydimethylsiloxane (PDMS) substrate. The first step of the research is oriented on the experimental study of the properties of TiNb based alloy and on the development of the orthopedic device. The second step is focalized on the electromagnetic characterization of the implanted printed antennas. The resulting smart orthopedic device incorporating the antenna and when embedded in a body environment is numerically analyzed from communication point of view. In particular, the radiation characteristics, necessary for the calculation of the link budget when the device is used for communication with the external to the body receiver is considered. Such scenario finds its applications in monitoring some vital human functions for example in post chirurgical rehabilitation or other long-term surveys

Prediction of Class-Amplifiers with the Aid of Neural Network

This paper presents a strategy addressing the problem of selection of the class of the amplifiers to be used in future wireless communication systems. The proposed methodology uses a scheme based on neural networks (NN): the characteristics of each class of amplifier (i.e., A, B, AB, C, D, F, G, J, S, T , etc.) are determined and then the ‘classification NN’ is constructed for distinguishing various classes from each other. To validate the method, firstly the designs of various class-amplifiers are collected from the recently published literature, and then the specifications of the amplifiers are extracted in terms of voltage (V), current (I) and efficiency; finally with these data the classification NN is trained. After building this black-box NN, providing the required specifications of each amplifier, designer are informed about the class of amplifier that is predicated by the classification NN and that better fits the characteristics of the considered application. This methodology is important as it leads the way of amplifier class selection in the complex communication systems

Surrogate Modeling for Designing and Optimizing MIMO Antennas

This papers presents the design and optimization of multiple-input and multiple-output (MIMO) antennas through intelligent methods namely as: surrogate modeling. The optimization process is performed automatically with the combination of Microwave Studio (Dassault Systèmes) and MATLAB numerical analyzer. The proposed optimization method aims to find the optimal solution for the total active reflection coefficient (TARC) specification, S 11 , and S 12 by using shallow neural network. This methodology leads to efficiently size the design parameters of MIMO antenna and to optimize S-parameters and TARC specification jointly. To validate the proposed method, an ultra wideband MIMO antenna in the frequency band of 3.1 GHz to 10.6 GHz is designed and optimized

Ultra-wide-band Circularly Polarized Mushroom-shaped Dielectric Resonator Antenna for 5G and sub-6 GHz Applications

In this paper, a mushroom shaped ultrawideband circularly polarized Dielectric Resonator Antenna (DRA) is proposed for lower 5G band and sub-6 GHz applications. The proposed DRA is excited by two orthogonal conformal probes and fed by a simple L shape microstrip feed network. The DRA exhibits wide impedance bandwidth of approximately 34.5% (3.5-5.1 GHz) with S11 better than -10 dB and wide circular polarization bandwidth of 33% (3.55-5 GHz) with axial ratio less than 3 dB in broadside direction. Mushroom-shaped DRA has a peak gain of 6.5 dBi and an average gain throughout the operating band is 5.5 dBi. Simulated results of the DRA are in good agreement with measured results of fabricated prototype. This DRA is a strong candidate for the sub-6 GHz and 5G band applications

Inhomogeneous metasurface to enlarge cloaking bandwidth

The main issues of cloaking problems are to increase the bandwidth of operation and to efficiently cloak electrically large objects. In order to overcome these problems, in this paper an inhomogeneous metasurface is proposed. The metasurface unit cell is composed of two metallic square patches with different lengths. Two arrangements of the single patches are analysed in terms of scattering field reduction and compared with a homogeneous structure