N. S. Raghava

Iris recognition on Hadoop: A biometrics system implementation on cloud computing

Cloud computing is one of the highly researched areas today, with an objective of taking advantage of various computational resources. In this paper we have used cloud computing environment with the aim to speed up the matching process of biometric traits. We have used iris recognition, a biometric technique, as it is one of the strongest method of authentication. Also Iris recognition is stable over time. We have used Hadoop [1], an open source cloud computing environment, to develop this model. Hadoop implements Map/Reduce [1] framework in Java. Map/Reduce make easy to process large amount of data on cloud. The results shows that there is an effective speedup and efficiency gain of Iris template matching on Hadoop process over sequential process.

Photonic Bandgap Stacked Rectangular Microstrip Antenna for Road Vehicle Communication

A compact design of a stacked rectangular microstrip antenna with shorting post on slotted ground for road vehicle communication is presented in this letter. The antenna consists of a two stacked rectangular patches with a shorting post on a dielectric substrate micromachined with a rectangular lattice of holes on the ground plane. These lattices of holes act as electromagnetic band-gap structure which improves the antennas efficiency. The whole structure is backed by a plane ground with a air gap of 8.5 mm

A novel patch antenna for ultra wideband applications

A compact microstrip patch antenna for ultra-wideband (UWB) applications is proposed. The antenna has a frequency bandwidth of 3.03GHz (4.73GHz–7.76GHz). The microstrip antenna has a planar geometry and consists of two patches, a circular radiating patch and a circular ring shaped parasitic patch. The design was simulated with the help of IE3D v.14 software and the different parameters of the patch antenna were computed. Results show that the proposed antenna has promising characteristics for UWB applications such as Wireless Personal Area Network (WPAN), microwave imaging for detecting tumors and cancers, home networking etc.

UWB and directive E-shaped metamaterial patch antenna

Left-handed materials, which have both negative permittivity and permeability, have been the area of potential research over a decade. This paper elucidates the design of a double-negative group (DNG) THz metamaterial, namely, E-shaped, having negative refraction ranging from 34.5 to 37.5 THz. Rectangular microstrip patch antenna (RMPA) with microstrip feed has been designed using Ansoft HFSS with RT Duroid (ϵr = 2.33) as substrate and having the same frequency range as that of the metamaterials negative region. Upon incorporation of proposed metamaterials array inside the antenna substrate, bandwidth of antenna increases by 4 THz and directivity of antenna increases by about 43% with E-shaped metamaterial.

Square wave analysis of dielectric rectangular waveguide

In this paper, rectangular wave guides have been analyzed using a square wave incidence which can be used for digital communicat ion techniques . The E 1/mnmode of propagation is solved using Eigen functions taking transverse propagation constant in different regions of dielectric waveguide and then the characteristic equations have been derived. The characteristic equations are solved graphically by mode matching inside and outside fields of waveguide. The normalized propagation constant so obtained, for square wave incidence is compared with the sinusoidal wave obtained by Marcatili method and other methods. The results match fairly well at frequencies near the cut-off of dielectric waveguide.

A highly efficient Rectangular Microstrip Antenna with hexagonal holes as an Electromagnetic Bandgap structure in the ground plane

Electromagnetic Bandgap (EBG) structures can stop propagation of electromagnetic waves of certain frequencies and hence can be applied to the design of microstrip antennas. In this paper, we present a Rectangular Microstrip Antenna (RMSA) with an EBG structure in the ground plane. Hexagonal holes are etched on the ground plane which acts as the EBG structure. This whole structure is backed by a plane ground with an air gap of 10.5mm. When compared to an RMSA of the same dimensions the antenna efficiency increased by 74%, the gain by 10dBi and the directivity showed an enhancement of 2 dBi.

Miniaturized UWB multi-resonance patch antenna loaded with novel modified H-shape SRR metamaterial for microspacecraft applications

We present the design and analysis of a novel modified H-shaped split ring resonator (SRR) metamaterial. It has negative permeability and permittivity characteristics with multi-band resonance for the X, Ku, and Ka frequency bands. Different configurations of the patch antenna have been analyzed with different orientations and positions of the metamaterial. Optimized performance was achieved with the new shape of the metamaterial antenna with an appreciable 9 dB gain, 77 GHz bandwidth, 100% radiation efficiency, and 65% reduction in active area. The second-order fractal metamaterial antenna achieves high miniaturization on the order of 1/21. This is truly a boon in the communications world, as a sharp beam with smaller physical dimensions is urgently required.

High gain, directive and miniaturized metamaterial C-band antenna

Abstract In this paper, design and analysis of U–T-shaped metamaterial antenna have been presented. It shows negative permittivity and permeability characteristics. The metamaterial array is embedded inside the substrate of rectangular microstrip patch antenna. Upon incorporation, directivity increases by 24% and gain increases by 18%. Results were compared with equivalent circuit analysis of patch antenna and are well in coherence with FEM (finite-element method)-based Ansoft HFSS (high-frequency structure simulator) simulation with around 1% error. Using fractal metamaterial antenna of first and second order iterative mathematics, antenna is miniaturized by 58 and 75% along with improvement in bandwidth.

A novel metamaterial for miniaturization and multi-resonance in antenna

Abstract A new type of metamaterial-inspired patch antenna designed for having multi-resonance and minituarization has been elucidated. A novel metamaterial formed by combining 2 segment labyrinth and capacitive loaded strip has been designed by combining negative permeability and negative permittivity characteristics respectively, to form a Double Negative Group metamaterial. By adding 4 unit cells to the microstrip patch antenna resonating at 30 GHz, secondary resonances have been created around 8.5, 17.7, 20 and 23.7 GHz. Seventy-two per cent miniaturization of the structure is obtained using metamaterial-inspired antenna, but at the cost of reduction in bandwidth.

High Gain Patch Antenna for WBAN Applications

This paper proposes a Rectangular Circularly Polarized Microstrip Patch Antenna (RCPPA) that can be used for WBAN applications. The antenna is operating at 869.3 MHz, with enhanced gain, directivity and efficiency. With truncations on diagonally opposite sides and coaxial feed on Y axis a right hand circular polarization has been achieved. The antenna also shows reduction in surface waves, has no back radiation and is thinner in physical size, which makes it more suitable for WBAN applications. The properties of proposed antenna is then compared with Compact Slot Loaded Patch Antenna (CSLPA), which is already being used for WBAN applications.