Nvsn Sarma

National Institute of Technology, Warangal, Electronics & Comm Engineering, Faculty Member

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Michael Spivey

University of California, Merced

Marc Champagne

Kwantlen Polytechnic University

Lukasz Kurowski

Centennial College , Toronto

Kathryn LaFevers Evans, Three Eagles

Pacifica Graduate Institute

Norhaslinda Kamaruddin

Universiti Teknologi Mara

Paul Williams

Indiana University

Joko Sampurno

TanjungPura University

Jamin Pelkey

Toronto Metropolitan University

MARIA RAMOS-ESCAMILLA,PhD

Universidad Iberoamericana - Mexico

Mojtaba Dehmollaian

University of Tehran

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Papers by Nvsn Sarma

Performance Analysis of a Differential Evolution Algorithm in Modeling Parameter Extraction of Optical Material

Silicon, 2016

Determination of accurate modeling parameters of optical materials prior to defining the material... more Determination of accurate modeling parameters of optical materials prior to defining the materials in the simulation model is fundamentally important to obtain simulation results close to the experimental ones. However, extracting modeling parameters of optical materials is inherently difficult because it involves fitting both real and imaginary parts of the relative permittivity using a single set of parameters. In this paper, an evolutionary algorithm called differential evolution (DE) has been utilized to extract the optical modeling parameters of graphene oxide. The performance of DE to find the optimal results has been analyzed by using different objective functions and boundary values. Two objective functions are used out of which one is proposed by us. Root-means-square (RMS) deviation, a measure of accuracy of the numerically obtained results has been determined for each case. From the obtained results it has been found that the DE algorithm extracted the optical modeling parameters successfully with very small RMS deviation for both real and imaginary parts of the complex relative permittivity.

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Gain and Bandwidth Improvement of Circularly Polarized Pentagonal Patch Antenna

2019 TEQIP III Sponsored International Conference on Microwave Integrated Circuits, Photonics and Wireless Networks (IMICPW)

A simple pentagonal patch antenna is designed and its feed position is optimized to get circular ... more A simple pentagonal patch antenna is designed and its feed position is optimized to get circular polarization. A superstrate consisting of capacitive, inductive and capacitive layers is introduced to enhance the gain of circularly polarized antenna and Reactive Impedance Surface(RIS) is inserted below the patch antenna to improve the bandwidth of circularly polarized antenna. A pentagonal patch antenna is known to be given 3-4dBi over a 7.26 %(4.91GHz-5.28GHz) impedance bandwidth normally, Axial ratio bandwidth is 1.90%. The gain and bandwidth are simultaneously enhanced for the first time by placing metamaterial superstrate and RIS. The simulated gain is 8-9dBi over a frequency band 11.80 %(4.88GHz - 5.49GHz), Axial ratio is increased to 2.88%(5.13GHz - 5.28GHz) after proper optimization of the entire antenna.

Printed cross-slot wideband conformai antenna for GPS application

2018 International Applied Computational Electromagnetics Society Symposium (ACES), 2018

A novel cross-slot printed wideband conformai antenna is proposed for GPS application. The combin... more A novel cross-slot printed wideband conformai antenna is proposed for GPS application. The combination of partial ground plane and cross-slot on the patch are used for bandwidth enhancement. The proposed conformal antenna exhibits a fractional bandwidth(for the definition of −10dB) of 79.28% operating from 1091 to 2524 MHz. The radiation pattern exhibits an omnidirectional pattern and gain of the proposed conformal antenna is 2.37 to 5.33dBi within operating frequency range.

$Research paper thumbnail of HIS based asymmetrical fractal boundary microstrip antenna$

HIS based asymmetrical fractal boundary microstrip antenna

2015 13th International Conference on Electromagnetic Interference and Compatibility (INCEMIC), 2015

This paper proposes design of a compact, asymmetrical fractal boundary microstrip patch antenna o... more This paper proposes design of a compact, asymmetrical fractal boundary microstrip patch antenna on high impedance surface (HIS) substrate to result in circular polarization (cp). The circular polarization radiation with compact size can be achieved by replacing sides of the square patch antenna with asymmetrical semi circle fractal curves along x and y axes respectively. A HIS is sandwiched between this patch and the ground plane. The 10-dB return loss bandwidth and 3-dB axial ratio bandwidth for proposed antenna are observed to be 57.26% and 14% respectively from simulations.

$Research paper thumbnail of RIS based poly fractal boundary microstrip antenna$

RIS based poly fractal boundary microstrip antenna

2015 31st International Review of Progress in Applied Computational Electromagnetics (ACES), 2015

A circularly polarized microstrip antenna with poly fractal boundary is proposed. The sides of a ... more A circularly polarized microstrip antenna with poly fractal boundary is proposed. The sides of a square patch are replaced with Minkowski and Koch fractal curves along x and y axes respectively for generating asymmetry in the structure to get circular polarization in the radiation. The corresponding poly structure is implemented over a Reactive Impedance Surface (RIS) for broadband operation. Simulations for poly fractal antenna are carried out with square and fractal RIS elements.

A Single Feed Circularly Polarized Wallis Sieve Fractal Microstrip Antenna

A new type of compact circularly polarized single feed microstrip antenna is pre- sented. In orde... more A new type of compact circularly polarized single feed microstrip antenna is pre- sented. In order to achieve the specifled characteristics Wallis sieve fractal geometry is employed. Simulated results indicate that the proposed antenna gives a very good circular polarization with minimum axial ratio very close to 0dB at the center frequency of 2430MHz and impedance bandwidth (at 10dB reference) of 4.25%. The antenna provides almost constant gain of about 3.2dBi over the frequency band of operation. This antenna can be used in WLAN, Bluetooth and WiMAX, Wi-Fi etc at ISM band. The antenna can also be used for multiband opearation. 1. INTRODUCTION Microstrip patch antennas are small size, low proflle antennas. Circularly polarized microstrip antennas flnd applications in difierent flelds like WLAN, GPS, Mobile satellite, RFID applications etc. It is required to design antennas with compact size without degradation in gain of the antenna in the said applications. The circular polarizati...

Ultra Wide Band conical monopole antenna for Wireless Applications

International Journal of Engineering Trends and Technology, 2016

Design of a conical monopole antenna is proposed for Ultra-Wide Band (UWB) wireless applications.... more Design of a conical monopole antenna is proposed for Ultra-Wide Band (UWB) wireless applications. The antenna design is suitable for different wireless standards, including Bluetooth (v1.0–v4.0), Wi-Fi (2.4 GHz), WiMAX (~ 2.5 to 5.5GHz) and Bluetooth 4.0 or Wireless USB (3.1– 10.6 GHz). The antenna operating frequency is also suitable for frequency range of satellite and radar communications; in X band (~ 8 to 12 GHz), Ku band (~ 12 to 18 GHz) and K band (~18 to 27 GHz). The approximate length of the proposed antenna design is 0.02λ where λ is calculated at the lowest frequency (0.4 GHz). The antenna comprises of two mechanical parts, one is a cylindrical block (disc) and other is a cone. The radiation pattern of the antenna is Omni directional in nature. Furthermore, it shows high gain across the bandwidth. The advantages are observed for UWB operation and compactness from the simulations. Keywords—conical monopole antenna, Wi-Fi, WiMAX, X band, Ku band, K band, ultra-wideband (UWB).

CSRR based patch antenna for Wi-Fi and WiMAX Applications

Advanced Electromagnetics, 2018

In this paper, a novel compact microstrip patch antenna is proposed for Wi- Fi and WiMAX bands. T... more In this paper, a novel compact microstrip patch antenna is proposed for Wi- Fi and WiMAX bands. To achieve miniaturization the dimensions of the square radiating patch are chosen with reference to the high frequency band (3.3 GHz). The dual band is achieved by loading a Complementary Split Ring Resonator (CSRR) into the radiating patch. The left handed nature of the CSRR is the cause for low frequency band (2.4 GHz). To improve the return loss bandwidth and axial ratio bandwidth at upper band the fractal concept is introduced along the edges of the square patch. Thus a low volume dual band antenna is simulated using HFSS. A comparison with measured data is also presented. The fabricated antenna is found to be occupying 25% less volume (with reference to 2.4 GHz) than existing antennas which is mainly due to the blending of the two recent concepts ‘metamaterials and fractals’.

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Triband Circularly Polarized Koch Fractal Boundary Microstrip Antenna

IEEE Antennas and Wireless Propagation Letters, 2014

A novel single-layer single-probe-feed asymmetrical fractal boundary microstrip antenna is consid... more A novel single-layer single-probe-feed asymmetrical fractal boundary microstrip antenna is considered for triband circular polarization (CP) operation. Four different structures-without-slot (Ant1), rectangular (Ant2), fractal (Ant3), optimized-fractal-slot (Ant4)-are studied for multiband CP radiation. Perturbation in the structure for triband CP radiation is introduced by employing optimized asymmetrical Koch fractal curves as boundaries of a square patch and embedded rectangular slot. The generated 3-dB axial-ratio bandwidths of Ant 4 are 3.2%, 1.6%, and 3.0% at operating frequencies around 2.45, 3.4, and 5.8 GHz, respectively. Measured results that are in close agreement with the simulation results demonstrate that the proposed antenna is well suited for the WLAN/WiMAX wireless applications.

Circularly polarized frequency reconfigurable Koch antenna for GSM/Wi-Fi applications

Microwave and Optical Technology Letters, 2015

A novel circularly polarized frequency reconfigurable Koch fractal boundary antenna is proposed. ... more A novel circularly polarized frequency reconfigurable Koch fractal boundary antenna is proposed. Initially, a Koch slot is etched on the Koch fractal boundary patch of larger dimension (48 3 48 mm 2 ). Within the etched slot, an asymmetrical Koch fractal patch of smaller dimension (36 3 36 mm 2 ) is embedded and switches are introduced along x and y-directions to connect these inner and outer patch structures. By making ON/OFF switching of the diodes frequency reconfiguration is achieved. Measured results are in close agreement with the simulation results which demonstrates that the proposed antenna is well suited for GSM/Wi-Fi wireless applications.

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Performance analysis of kernel based adaptive beamforming for smart antenna systems

2014 IEEE International Microwave and RF Conference (IMaRC), 2014

In this paper, kernel based adaptive algorithms for smart antenna systems are considered to achie... more In this paper, kernel based adaptive algorithms for smart antenna systems are considered to achieve the best weight vector for beamforming by iteration process. Smart antenna systems radiate not only narrow beams towards desired signal directions, but also place deep nulls in the undesired signal directions, thus optimizing the signal quality, and enhancing the coverage range. The performance of the algorithms are studied with parameters, like convergence speed and minimum mean square error. Based on simulation results, it is proved that kernel based adaptive algorithm provides better performance in terms of weight convergence, null steering and power gain over that of the traditional least square algorithm. Therefore, the kernel based algorithm gives a cost effective solution in mobile communication under dynamic channel environment to enhance capacity and range.

AES based secure low energy adaptive clustering hierarchy for WSNs

International Conference on Communication and Electronics System Design, 2013

Wireless sensor networks (WSNs) provide a low cost solution in diversified application areas. The... more Wireless sensor networks (WSNs) provide a low cost solution in diversified application areas. The wireless sensor nodes are inexpensive tiny devices with limited storage, computational capability and power. They are being deployed in large scale in both military and civilian applications. Security of the data is one of the key concerns where large numbers of nodes are deployed. Here, an energy-efficient secure routing protocol, secure-LEACH (Low Energy Adaptive Clustering Hierarchy) for WSNs based on the Advanced Encryption Standard (AES) is being proposed. This crypto system is a session based one and a new session key is assigned for each new session. The network (WSN) is divided into number of groups or clusters and a cluster head (CH) is selected among the member nodes of each cluster. The measured data from the nodes is aggregated by the respective CH’s and then each CH relays this data to another CH towards the gateway node in the WSN which in turn sends the same to the Base station (BS). In order to maintain confidentiality of data while being transmitted, it is necessary to encrypt the data before sending at every hop, from a node to the CH and from the CH to another CH or to the gateway node.

Radar emitter classification using self-organising Neural Network models

2008 International Conference on Recent Advances in Microwave Theory and Applications, 2008

Abstract - This paper presents a Radar Emitter Identification and Classification technique based ... more

$Research paper thumbnail of Probe compensated single feed circularly polarized fractal-shaped microstrip antennas$

Probe compensated single feed circularly polarized fractal-shaped microstrip antennas

International Journal of RF and Microwave Computer-Aided Engineering, 2009

ABSTRACT: A single feed circularly polarized fractal boundary microstrip antenna with improved ax... more

Compact Circularly Polarized Asymmetrical Fractal Boundary Microstrip Antenna for Wireless Applications

IEEE Antennas and Wireless Propagation Letters, 2014

Compact fractal boundary microstrip antenna is proposed for circular polarization (CP). By replac... more Compact fractal boundary microstrip antenna is proposed for circular polarization (CP). By replacing the sides of a square patch with asymmetrical prefractal curves, two orthogonal modes are excited for CP operation. The structure is asymmetric along the principal axes (x, y). The indentation parameter of the fractal boundary curve is optimized to design compact CP antennas. Experimental results show that 10-dB return loss and 3-dB axial-ratio bandwidths of the proposed fractal boundary Ant 2 are 162 and 50 MHz, respectively, at operating frequency of around 2540 MHz. Results show that an excellent CP is achieved with a single probe feed, besides reduction in the antenna size by applying fractal boundary concept.

A Novel Method for Recognition of Modulation Code of LPI Radar Signals

signal, 2009

Abstract The Low Probability of Intercept (LPI) capability of the radar defeats conventional RWR... more

The Effect of Indentation Angle of Koch Fractal Boundary on the Performance of Microstrip Antenna

International Journal of Antennas and Propagation, 2008

The effect of indentation angle of Koch fractal boundary applied to a triangular patch on the res... more The effect of indentation angle of Koch fractal boundary applied to a triangular patch on the resonant behavior and bandwidth is presented. It is shown that the resonant frequency can be controlled by changing the indentation angle of the boundary. With the experimental verification, it is established that for an indentation angle of more bandwidth is obtained compared to conventional .

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Single Feed Circularly Polarized Poly Fractal Antenna For Wireless Applications

A circularly polarized fractal boundary microstrip antenna is presented. The sides of a... more A circularly polarized fractal boundary microstrip antenna is presented. The sides of a square patch along x- axis, yaxis are replaced with Minkowski and Koch curves correspondingly. By using the fractal curves as edges, asymmetry in the structure is created to excite two orthogonal modes for circular polarization (CP) operation. The indentation factors of the fractal curves are optimized for pure CP. The simulated results of the novel polyfractal antenna are demonstrated.

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A wideband conformal slot antenna for GPS application

2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL), 2017

A novel wideband conformal slot antenna is proposed for GPS application. Initially a planar anten... more A novel wideband conformal slot antenna is proposed for GPS application. Initially a planar antenna with dumbbell shape slot on three sides of patch is designed at a slightly higher frequency and then the planar antenna is transformed to the corresponding cylindrical conformal antenna with the desired radius of curvature. The antenna used in this study employs a dumbbell shape slot on the three sides of patch. To design the wideband antenna, combination of partial ground concept and dumbbell shape slots on patch is employed. The flexible and higher thermal stable substrate like Rogers RT/duroid 5880 with permittivity of 2.2 and thickness of 0.787 is used. Microstrip line feeding is used in the proposed antenna. The proposed conformal antenna exhibits a fractional bandwidth (for the definition of −10 dB) of 75.94% operating from 1056 to 2349 MHz, which is suitable for all GPS band, GLONASS and GALILEO application. The radiation pattern exhibits an omnidirectional pattern and gain of proposed conformal antenna is 2.09 to 4.9 dBi within operating frequency range.

Hybrid Taguchi-Genetic algorithm based beamforming for smart antenna system

2015 13th International Conference on Electromagnetic Interference and Compatibility (INCEMIC), 2015

This paper describes smart antenna array beamforming using hybrid Taguchi-Genetic evolution algor... more This paper describes smart antenna array beamforming using hybrid Taguchi-Genetic evolution algorithm. The electromagnetic interference is reduced by controlling sidelobe levels and placing nulls in the undesired directions. Based on the concept of the orthogonal array, Taguchi method effectively reduces the number of tests required in an optimization process. This method effectively obtains the optimum weights for efficient beamforming performance. The attributes of Taguchi and Genetic algorithms are used effectively to improve the adaptive beamforming in smart antenna system. The proposed algorithm uses the orthogonal concept in between crossover and mutation operations of a genetic algorithm to improve the performance and fast convergence. Numerical results are presented to verify the convergence, and computational efficiency of the proposed hybrid Taguchi-Genetic algorithm.