Ahmadābād, India
Ahmadābād, India

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Alad R.H.,Dharmsinh Desai University | Chakrabarty S.,Antenna Systems Group
IEEE Transactions on Plasma Science | Year: 2015

This paper presents the evaluation of a capacitance matrix and the temporal body potential of an artificial orbiting satellite considering a metallic cuboid, parabolic reflector antennas, and solar panels. Integral equations are formed by relating the unknown charge density on the metallic conductor and are solved using the method of moments, in which the pulse functions are used as basis functions and the delta functions are used as testing functions. The surfaces of the conducting structure are meshed using nonuniform triangular subareas. The matrix equations are solved using an iterative generalized minimum residual algorithm. The numerical data on the capacitance matrix and the charge distribution of these structures have been presented. The validity of this analysis has been established by comparing the data on capacitance available in the literature for the metallic cuboid with the data on capacitance computed by the present method for similar structures. The temporal behavior of body potential of the satellite is computed for different cases. © 2015 IEEE.


Alad R.H.,Dharmsinh Desai University | Chakrabarty S.B.,Antenna Systems Group
Progress In Electromagnetics Research B | Year: 2012

This paper presents comparative studies on different types of basis and testing functions used in Method of Moments (MoM) in terms of analytical complexity, convergence and condition number of the co-efficient matrix when applied to electrostatic problem of evaluating capacitance and charge distribution of conducting bodies. A thin conducting cylinder of finite length has been taken as a representative case study to evaluate the capacitance and charge distribution. The basis and testing functions which have been studied for this problem are pulse-delta, pulse-pulse, triangular-delta, triangular-pulse and triangular-triangular functions respectively. Numerical data on capacitance and charge distribution has been presented for each set of basis and testing functions in terms of condition number and convergence.


Alad R.H.,Dharmsinh Desai University | Chakrabarty S.B.,Antenna Systems Group
Indian Journal of Radio and Space Physics | Year: 2015

The paper presents the evaluation of capacitance matrix of an artificial orbiting satellite considering a composite metallic structure of a parabolic reflector antenna with cuboid and plates. Integral equations are formed by relating the unknown charge density on the metallic conductor and are solved using the Method of Moments (MoM) in which the pulse functions are used as basis functions and the delta functions are used as testing functions. The surfaces of the conducting structure are meshed using non-uniform triangular patches. The matrix equations are solved by iterative generalized minimum residual (GMRES) algorithm. The numerical data on the capacitance matrix and charge distribution of these structures have been presented. The capacitance of a metallic cuboid is computed to validate the approach.


Bhattacharya A.,University of Burdwan | Sahu L.K.,University of Delhi | Jyoti R.,Antenna Systems Group
IEEE MTT-S International Microwave and RF Conference 2014, IMaRC 2014 - Collocated with Intemational Symposium on Microwaves, ISM 2014 | Year: 2015

A zigzag shaped, single band, small size Planar Inverted F antenna (PIFA) at 2.45 GHz is introduced and investigated. Total size of the antenna is 15mm × 6 mm which complies easily for integration with other devices viz. USB dongle. S11 of-32 dB at 2.45 GHz with-10 dB bandwidth of 4.2% has been obtained. Gain of the antenna is-1.82 dBi and pattern is omnidirectional. For proper matching with 50 Ω source, a transformer has been integrated at feeding point. The structure has been simulated using commercial available Ansys HFSS simulator. There is good agreement between simulated and measured results. The patterns are omni-directional which proves that the antenna is a good candidate for wireless communications. © 2014 IEEE.


Mahajan M.,Antenna Systems Group | Jyoti R.,Antenna Systems Group | Sood K.,Antenna Systems Group | Sharma S.B.,INDUS Technology
IEEE Transactions on Antennas and Propagation | Year: 2013

This communication deals with simultaneous generation of a contoured and a pencil beam from a single shaped reflector with two feeds. A novel concept of generating a high gain pencil beam from a shaped reflector is presented using focal plane conjugate field matching method. The contoured beam is generated from the shaped reflector by introducing deformations in a parabolic reflector surface. This communication proposes a simple method to counteract the effects of shaping and generate an additional high gain pencil beam from the shaped reflector. This is achieved by using a single feed which is axially and laterally displaced from the focal point. The proposed method is successfully applied to generate an Indian main land coverage contoured beam and a high gain pencil beam over Andaman Islands. The contoured beam with peak gain of 33.05 dBi and the pencil beam with 43.8 dBi peak gain is generated using the single shaped reflector and two feeds. This technique saves mass and volume otherwise would have required for feed cluster to compensate for the surface distortion. © 2013 IEEE.


Dey R.,Antenna Systems Group | Chakrabarty S.,Antenna Systems Group | Jyoti R.,Antenna Systems Group | Kurian T.,Indian Institute of Space Science and Technology
IET Microwaves, Antennas and Propagation | Year: 2016

This study presents the design and analysis of linear as well as cubic spline interpolated profiled smooth-wall multimode horn using mode matching (MM) technique along with genetic algorithm (GA) and particle swarm optimisation (PSO). To apply the MM technique, the smooth profile conical geometry is assumed to consist of cascaded sections of large number of small symmetrical radial steps. Scattering matrix for each section has been calculated using MM technique and over all scattering matrix of the cascaded junctions has been calculated using generalised scattering matrix technique. The radiation pattern has been calculated using hybrid boundary contour mode matching technique. Optimisation of the linear/spline profile horn has been carried out using GA as well as PSO. Detailed modal analysis along with the convergence of the present technique for the smooth profile structure has also been carried out. A spline profile multimode horn working at 89 GHz has been designed and developed. The present analysis has been verified with the measured results. There is a very good agreement between theoretical and measured results. © 2016. The Institution of Engineering and Technology.


Dey R.,Antenna Systems Group | Chakrabarty S.B.,Antenna Systems Group | Jyoti R.,Antenna Systems Group
Electromagnetics | Year: 2016

This article presents the analysis of scattering characteristics of three symmetrical radially directed thin posts in an oversized circular waveguide in the transverse plane using the method of moments. Simulated data on return loss of the dominant mode and higher-order mode TE21 have been compared with the data computed using Ansys high frequency structure simulator (HFSS; Canonsburg, PA, USA). The data on return loss for the incident TE11 mode have been compared with experimental data for an oversized cylindrical waveguide loaded with the three posts. Also, the above analysis has been applied for designing a conjugate matched feed horn, which is used to cancel the cross-polar components generated in an offset reflector antenna. The primary pattern of the conjugate feed horn has been simulated and optimized using Ansys HFSS. The secondary pattern has been calculated using a general reflector antenna software package (GRASP; TICRA Engineering Consultants, Denmark). © 2016 Taylor & Francis.


Dey R.,Antenna Systems Group | Dey R.,Indian Institute of Space Science and Technology | Chakrabarty S.B.,Antenna Systems Group | Jyoti R.,Antenna Systems Group
Microwave and Optical Technology Letters | Year: 2013

This article presents the investigation on the applicability of variational technique for the estimation of input impedance of a coaxial line fed probe in a circular cylindrical waveguide based on thin current approximation. In this work, the lower limit of diameter of the probe for which thin current approximation is valid has been established. The variation of input impedance has been studied as a function of probe height, short length from the probe as well as diameter of the probe. The convergence of the solution based on variational technique is checked in terms of the number of higher order modes of circular cylindrical waveguide excited at the asymmetrical junction of probe. The limitation of the existing technique has been ascertained using the finite element method based simulator high frequency structure synthesizer (HFSS) and experimental validation. The simulated result based on HFSS is in excellent agreement with the experimental results. Bandwidth performance with variation in diameter has also been studied using HFSS simulator with varying probe diameter. © 2013 Wiley Periodicals, Inc.


Chakrabarty S.,Antenna Systems Group | Jyoti R.,Antenna Systems Group
2015 IEEE Applied Electromagnetics Conference, AEMC 2015 | Year: 2015

Absolute charging analysis of space-craft bodies using MoM has been presented. Integral equations are formed by relating the unknown charge density on the metallic conductor. Pulse functions are used as basis functions and the delta functions are used as testing functions. The surfaces of the conducting structure are meshed using non-uniform triangular sub-areas. The matrix equations are solved by using iterative algorithm. The numerical data on the capacitance matrix and charge distribution of these structures have been presented. The temporal behavior of body potential of the satellite is computed. © 2015 IEEE.


Bhattacharya A.,University of Burdwan | Jyoti R.,Antenna Systems Group
2015 IEEE 2nd International Conference on Recent Trends in Information Systems, ReTIS 2015 - Proceedings | Year: 2015

In this paper the design of an X-band frequency reconfigurable patch antenna has been demonstrated using PIN diode. A square slot has been introduced in order to realize PIN diode effect in antenna parameters. The tuning of frequency is realized by changing its effective electrical length, which is controlled by different mode of the PIN diode by applying different bias voltages across it along the slot of the antenna. An annular slot rectangular patch antenna is used and a gap of 2mm is used to attach PIN diode. When the PIN diode is forward biased i.e gap is closed by PIN diode and current will flow along the outer ring. ±60 MHz (1.34 %) tuning of frequency has been obtained by applying the bias voltage of 3 volt. The structure has been simulated in ADS software. Simulated and measured performances are presented. Results are used to demonstrate that there is good agreement between the simulated and measured results. The match between simulation and measured results suggests that proposed candidate can be used as a frequency reconfigurable antenna. © 2015 IEEE.

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