Asok De

A Novel Microstrip Patch Antenna with Large Impedance Bandwidth in VHF/UHF Rang

In this paper a novel antenna is presented. This antenna, employing microstrip circular disc as radiator is seen to perform over a large impedance bandwidth (130 MHz to 876 MHz). The disk resonator is loaded with L-C-R circuit across a selective location in the disk via a thin shorting pin. The theoretical modeling predicts TM01 mode of operation. Therefore the beam pattern shows a null in the broadside direction. The said antenna is proposed to be developed for end use in coal mine where the antenna can be flush mounted on coal strata. Thus it will be able to measure the angle of arrival of any reflective component due to presence of waterbed at a distance. The measured as well as simulated results regarding impedance bandwidth and beam pattern agrees well. The simulated efficiency using IE3D is 48% whereas measured efficiency is nearly 45%.

Prediction of Slot-Size and Inserted Air-Gap for Improving the Performance of Rectangular Microstrip Antennas Using Artificial Neural Networks

Artificial neural networks have been getting popularity for predicting various performance parameters of microstrip antennas due to their learning and generalization features. In this letter, a neural-networks-based synthesis model is presented for predicting the “slot-size” on the radiating patch and inserted “air-gap” between the ground plane and the substrate sheet, simultaneously. Different performance parameters like resonance frequencies, gains, directivities, antenna efficiencies, and radiation efficiencies for dual resonance are observed by varying the dimensions of slot and inserted air-gap. For validation, a prototype of microstrip antenna is fabricated using Rogers substrate, and its performance parameters are measured. Measured results show a very good agreement to their predicted and simulated values.

Numerical Computation of Resonant Frequency of Gap Coupled Circular Microstrip Antennas

In this paper the numerical computation of resonant frequency of gap coupled circular microstrip antennas using the concept of cavity model has been presented. The resonant frequency of the gap-coupled circular patches is computed and the mode number is also evaluated. The computed results are compared with published results. The previously published results are based on experimentation and do not present a clear mathematical model for the same structure. An extensive comparison with Method-of-moments based software (IE3D) is also done. The accuracy of prediction is reasonably good.

Which verification qubits perform best for secure communication in noisy channel

In secure quantum communication protocols, a set of single qubits prepared using 2 or more mutually unbiased bases or a set of n-qubit

Numerical Analysis of Two Dimensional Tapered Dielectric Waveguide

(n\ge 2)

Photonic Bandgap Stacked Rectangular Microstrip Antenna for Road Vehicle Communication

(n≥2) entangled states of a particular form are usually used to form a verification string which is subsequently used to detect traces of eavesdropping. The qubits that form a verification string are referred to as decoy qubits, and there exists a large set of different quantum states that can be used as decoy qubits. In the absence of noise, any choice of decoy qubits provides equivalent security. In this paper, we examine such equivalence for noisy environment (e.g., in amplitude damping, phase damping, collective dephasing and collective rotation noise channels) by comparing the decoy-qubit-assisted schemes of secure quantum communication that use single-qubit states as decoy qubits with the schemes that use entangled states as decoy qubits. Our study reveals that the single- qubit-assisted scheme performs better in some noisy environments, while some entangled-qubit-assisted schemes perform better in other noisy environments. Specifically, single-qubit-assisted schemes perform better in amplitude damping and phase damping noisy channels, whereas a few Bell-state-based decoy schemes are found to perform better in the presence of the collective noise. Thus, if the kind of noise present in a communication channel (i.e., the characteristics of the channel) is known or measured, then the present study can provide the best choice of decoy qubits required for implementation of schemes of secure quantum communication through that channel.

SLA Based Scheduler for Cloud for Storage & Computational Services

In this paper a novel method of generation of ultra- low resonance in a microstrip disk resonator is presented. The disk resonator is loaded with series L-C circuit across a selective location in the disk via a thin shorting pin. It is shown that in loaded disk resonator, the lowest resonance observed is in VHF range whereas the unloaded disk had a fundamental resonance at 1.76 GHz. This resonance is slightly offset from the series resonant frequency of L- C circuit. and it depends on the disk radius as well. Using IE3D, a commercial MoM solver, the said structure is simulated. The experimental results agree well with the simulated results. A closed form expression for computing the resonant frequency is given.

Software Implementation of Curve based Cryptography for Constrained Devices

A simple method is presented to obtain the scattering parameters of the two dimensional tapered dielectric waveguide, by discrete approximation to tapering, consisting of series of steps. The two dimensional step discontinuity of the junction of two different dielectric rectangular waveguides has been solved using integral equation arising from the field matching of the discrete modes and the continuous spectrum. Accurate numerical solution has been obtained using Ritz-Galerkin variational approach with appropriate sets of expanding functions. The results in the form of scattering parameters for varying tapered length have been depicted graphically. Computed results from generalized integral expressions are found to be in excellent agreement with results obtained in two-dimensional case. With this method it is possible to design the structure to enlarge the cross section of a mode in a slow and controlled manner.