Md. Abdul Matin

NOVEL DESIGN OF TRIPLE BAND RECTANGULAR PATCH ANTENNA LOADED WITH METAMATERIAL

In this paper, for the very flrst time, triple band rectangular patch antenna loaded with metamaterial has been reported. Maximum directivities demonstrated here for all the three bands are quite high in comparison with previously reported any kind of rectangular patch antenna. This unique triple band performance has been achieved with the help of newly produced TM0-0 (3 < - < 4) mode, symmetric slot loading and parasitic patch adjustment. Application of etched slot and parasitic patch in DPS (double positive)-metamaterial juxtaposed layer loaded antenna has been also demonstrated for the flrst time. Considering the quite satisfactory performance (S-parameter, radiation pattern and radiation e-ciency) of this novel design, we expect that our proposed ideas will be very efiective to design all these metamaterial loaded novel rectangular patch antennas.

Optimization of Jiles-Atherton Hysteresis Model Parameters Using Taguchi’s Method

The parameters of Jiles-Atherton hysteresis model is optimized using Taguchis method. The method finds optimum values of the model parameters such that best agreement is achieved between measured and modeled hysteresis loops. The model parameters of two magnetic materials, a conventional non-oriented steel and a modern amorphous material, are calculated. The Taguchis method-based proposed approach is compared with particle swarm optimization (PSO), differential evolution (DE), and genetic algorithm (GA)-based approaches. The proposed approach is found to produce the minimum error between measured and modeled hysteresis loops. Taguchis method is also found to converge faster than PSO, DE, and GA-based methods.

Robust Optical Fiber Using Single Negative Metamaterial Cladding

We introduce the idea of optical fibers made up of single negative metamaterial photonic crystal cladding with zero effective phase bandgap. Fiber characteristics are analyzed both at sub-wavelength and non sub-wavelength crystal dimension by varying cladding thickness and core radius. We find that in both cases they are robust with respect to incident angle, polarization of the light, crystal constant, and cladding irregularities. The fiber is found to behave like a step index fiber but the guided modes are leaky like Bragg fiber. It is shown that a fixed cladding thickness produces fixed loss around impedance matching frequency irrespective of crystal constant.

Modeling of threshold voltage of a quadruple gate transistor

In this paper, a three dimensional analytical solution of electrostatic potential is presented for undoped (or lightly doped) quadruple gate MOSFET by solving 3-D Poissons equation. It is shown that the threshold voltage predicted by the analytical solution is in close agreement with TCAD 3-D numerical simulation results. For numerical simulation, self-consistent Schrodinger-Poisson equations, calibrated by 2D non equilibrium green function simulation, are used. This analytical model not only provides useful physics insight of effects of gate length and body width on the threshold voltage, but also serves as a basis for compact modeling of quadruple gate MOSFETs.

Can gen-4 nuclear power and reactor technology be safe and reliable future energy for developing countries?

For the promising population, the growing demand of energy has delicate the requirement of alternative sources of energies other than fossil fuels. Though renewable energy resources like solar, biomass, hydro and geothermal energy appear as environment friendly, replenishing sources of energy, a comprehensive solution appears far-fetched as far as large scale production and wide-spread dissemination is concerned when long term cost factors are taken into consideration. The unwavering boost of population and ongoing depletion of fossil fuels and have further exacerbated the energy crisis. In this paper, discussions on the limitations of conventional and renewable sources of energy compared to advanced fourth generation nuclear power on the basis of environmental contamination, energy security, cost of fossil fuels and electricity generation and have philosophy to the prospects of nuclear power as the ultimate future energy option for the developing countries are done. Environmental issues, long term cost factors, radiation hazard and safety concerns have been considered with respect to the generation of electricity using advanced third Generation nuclear power. This study proposes that gen-4 nuclear appears to be a long term environment favorable panacea to the much discoursed problem of energy crisis by maintaining energy security and long term cost concern in developing countries as well as in the whole world.

Tunable slow light with graphene based hyperbolic metamaterial

Slow light has always been a topic of extreme interest for researchers and scientists in order to utilize the full potential of light in switching, memory devices and in quantum optics. However, slow light phenomena and its potential applications in switching and memory devices by tunable graphene based hyperbolic metamaterial have not still been introduced in literature. Here we theoretically propose and numerically analyze a graphene based tunable slow light device from the concept of controlling the group velocity of light in hyperbolic metamaterials. In THz range, graphene-dielectric stack can behave as hyperbolic metamaterials and hyperbolic metamaterials can demonstrate slow light phenomena while being cladded by air. By utilizing the tunability option of graphene, proposed devices can be made tunable, which is the most important criteria to manage the full advantage of slow light. It ultimately paves a fully new way to find novel applications in photonic switch, optical buffers and memory devices. Interestingly, in such graphene based devices, voltage will play a vital role to control the group velocity of light from slow to fast and the carriers are photons instead of electrons.

Conceptual and practical realization of reduced size multi-band circular microstrip patch antenna loaded with MNG metamaterial

In this paper, an MNG metamaterial loaded circular microstrip patch antenna has been reported. This antenna not only shows multi-band performance but also provides maximum possible size reduction (35%) with realizable gain performance. Achieving triple band performance was made possible by modifying TMδ10(0<;δ<;1) mode (using μ-negative metamaterial) along with TM210 mode modification with symmetrical slots. At first, simulation performance of this antenna on the basis of proper design algorithm [1] has been shown. Later, with appropriate choice of parameters, a practical modeling of MNG metamaterial using helices that can be used to fabricate this sort antenna, has been demonstrated for verification. In [2] three helices were used to fabricate MNG metamaterial, but here it is shown that one helix provides better directivity instead of three. This will certainly minimize fabrication complexity in MNG metamaterial.

Analytical Deduction of the Salient Properties of a Half Wavelength J-Pole Antenna

In this paper, the analytical treatment of a half wave J-pole antenna has been carried out assuming a sinusoidal current distribution. The important properties of this type antenna have been compared with that of a half-wave dipole. It is observed that a J-pole antenna has better performance in terms of directivity. The directivity of this antenna has been found to be 2.3 dB which is slightly greater than that of a half wave centre fed dipole antenna. The gain of the antenna has been found to be better than that of a half-wavelength dipole antenna and the radiation resistance to be nearly equal to that of half wave-length dipole antenna.

Modeling the illumination function of a cassegrain reflector for a corrugated horn feed and calculation of the far field pattern

A model of the illumination function of cassegrain reflector for a corrugated horn feed is presented here. A conical corrugated feed horn designed for a Ku band cassegrain reflector is simulated. The simulation data is compared to the illumination function. Comparison between the developed illumination function and the widely used quadratic on a pedestal function is also presented. Finally, the developed illumination function is used to calculate the radiation pattern of the cassegrain reflector by evaluating the aperture field integration.

A Theory of Loss-less Compression of High Quality Speech Signals with Comparison

The field of speech compression has advanced rapidly due to cost-effective digital technology and diverse commercial applications. In voice communication a real-time system should be considered. It is not still possible to compress signals without facing any loss in real-time system. This paper presents a theory of loss-less digital compression for saving high quality speech signals. Emphasis is given on the quality of speech signal. In hearing music high quality music is always needed, consuming smaller memory space. In this compression 8-bit PCM/PCM speech signal is compressed. When values of samples are varying they are kept same. When they are not varying the number of samples containing same value is saved. After compression the signal is also an 8-bit PCM/PCM but expansion is needed before hearing it. This technique may also be used in real-time systems.