Arnab Nandi

Graphene-based wideband antenna for aeronautical radio-navigation applications

Abstract In this paper, a conductive layer is developed by printing a graphene nanoparticles-based conductive ink on the silk fabric showing surface resistance of 2.3 S and conductivity of Sm, respectively. The printed silk fabric is utilized to fabricate mode wideband antenna for aeronautical radio-navigation applications centered at 4200 MHz. Excellent impedance bandwidth of 26.4% is obtained by incorporating a patch-ground shorting stub. The antenna has reasonable radiation efficiency above 74% including packaging losses and conical radiation pattern at higher order mode. The simulation and measurements are performed considering practical scenario showing excellent measured results.

Performance of Incremental Redundancy-Based Data Transmission in Randomly Deployed Wireless Sensor Network

Energy-level performance of Incremental Redundancy (IR)-based Hybrid Automatic Repeat reQuest (HARQ) scheme using punctured convolution code is evaluated for randomly deployed wireless sensor network (WSN) in the presence of multipath Rician fading. Transmission based on HARQ and optimal power are two different promising approaches for reducing energy consumption in an energy constrained WSN. Optimal transmit power is the minimum power required to sustain the network connectivity while maintaining a predefined maximum tolerable BER threshold in a multihop route. In the present work, energy-level performance of HARQ scheme is compared with that of optimal transmit power-based coded and uncoded schemes for a random WSN. Further, energy consumption for an arbitrary fixed power-based coded scheme is also compared. In a random network, an intermediate node in the route selects the nearest node within a sector of angle (θ) toward the direction of the destination as the next hop. Effects of fading, node density, and search angle on selection of optimum power, energy consumption of optimum power-based scheme, and IR scheme are investigated. Effects of code rate and bit rate on energy consumption, route BER, and optimum power selection in case of optimum power-based coded scheme are indicated.

A Reconfigurable Defected Ground Structure Resonator Based on Coplanar Waveguide

A reconfigurable defected ground structure (DGS) resonator based on coplanar waveguide (CPW) technology is being proposed. The reconfigurable resonator leads to generate multiple stopbands at arbitrary frequencies. Basically, the design is based on slot defect which is thereby created on the ground plane. Here, two different states of diode configuration are being proposed, and in particular state, multiple transmission zeros are achieved in the 0–12 GHz frequency range. To identify the transmission zeros, the slotline design equations are used. Moreover, the conventional circuit parameter extraction method is used to extract the equivalent circuit diagram of each state.

Graphene-based multimode inspired frequency reconfigurable user terminal antenna for satellite communication

This study proposes a graphene conductive ink printed textile-based microstrip antenna capable of switching between S-band (3.03 GHz, TM 10 mode) and C-band (5.17 GHz, TM 02 mode and 6.13 GHz, TM 20 mode). The graphene conductive ink printed textile shows surface resistance of 2.7 Ω Sq. -1 , conductivity of 0.37 × 105 Sm -1 and excellent microstructural characteristics, which makes it suitable to be used as a metal sheet to fabricate the antenna structure. To overcome the low-conductivity issue of graphene conductive ink, a multilayered substrate approach is utilised to improve radiation performances of the antenna. A peak realised gain of 2.09 dBi and radiation efficiency of 74% is achieved at the dominant mode (3.03 GHz). The frequency reconfigurability is introduced by exciting the higher order modes, TM 02 and TM 20 through two different feeding locations. The excitation of ports is controlled through a radio frequency (RF) pin diode switch integrated microstrip transmission line. Subsequently, the proposed structure is further designed using copper foil of thickness (17 μm) and a comparative analysis of graphene-based and copper-based antennas is presented. The proposed antenna performs substantially well in terms of peak realised gain and radiation efficiency compared with that of the existing graphene-based antenna and the performance deviation with respect to the copper based antenna is lowered significantly.

Cooperative spectrum sharing with multi antenna based Amplify-and-Forward and Decode-and-Forward Relay

Performance of a cooperative spectrum shearing with the help of a multi-antenna based cognitive relay (CR) employing best relay selection strategy is analyzed in presence of non-identical Rayleigh fading channel in this paper. A cognitive relay equipped with multiple antennas at the input employs selection combining (SC) on the signals received from secondary user source (S) via multiple receiving antenna at the input and forwards the received signal to secondary user destination (D) using a Amplify-and-Forward (AF) and Decode-and-Forward (DF) protocols. The outage probability performance has been evaluated, when received signals are coherently combined at both the relays with multi-antenna and destination using Selection Combining (SC) and Best Relay (BS) selection schemes respectively. The effects of number of relay antennas (L) and number of relays (K) on the system performance have also been studied. A tradeoff between relay antennas and number of relays is also indicated.

Rectangular microstrip antenna with cross headed dumbbell defected patch surface for improved polarization purity

A simple and compact rectangular microstrip antenna with cross headed dumbbell defected patch surface is proposed for noteworthy suppression of cross polarized (XP) radiation, eliminating higher order orthogonal resonance without altering its dominant mode field configuration. The proposed antenna has been studied experimentally with theoretical justifications. More than 28 dB of XP radiation isolation from peak co polarized (CP) radiation is revealed.

Energy level performances of data services in random WSN with Rayleigh fading

Energy level performances of two packet delivery schemes in random WSN (Wireless Sensor Networks) are evaluated in presence of Rayleigh fading. Two different information delivery mechanisms involving regenerative relays with or without error correcting capability are investigated. Energy consumption for successful delivery of a data packet for each mechanism is evaluated and compared under several conditions of node density, bit rate, transmit power and channel fading. Energy efficiencies of the above schemes in a random WSN are also evaluated. In a random network, an intermediate node in the route selects the nearest node within a sector of angle (called search angle) towards the direction of the destination as the next hop. The impact of search angle on energy consumption, energy efficiency and BER are also investigated. Further an optimal packet length based on energy efficiency is derived. Impact of optimal packet size on total energy expenditure is analyzed for each delivery scheme.