Indian J. Phys. 83 (10) 1385-1394 (2009)
Non performance estimation of a microwave
communication link due to rain during the monsoon months
of 2006 over Kolkata
S K Sarkar*, M M Gupta, Iqbal Ahmad and C J Johny
Radio and Atmospheric Sciences Division, National Physical Laboratory,
Dr. K S Krishnan Road, New Delhi-110 012, India
A K De
Electronics and Sciences Communication Unit, Indian Statistical Institute,
203, B T Road, Kolkata-700 035, India
and
D Punyaseshudu
Department of Physics, Rayalseema University, Kurnool-518 002, Andhra Pradesh, India
E-mail : sksarkar@mail.nplindia.ernet.in
Received 15 May 2008, accepted 17 February 2009
Abstract : The non performance of a microwave communication link located over Kolkata due to heavy rain
in the monsoon months of 2006 has been investigated by monitoring the amplitude variation of signal on twenty
hour basis. It has been seen that the link did not serve any purpose for 4% during the monsoon period of 2006
while the signal level was less than –78 dBm. Infact the study revealed that the link performance started
deteriorating when the signal was of the order of –73 dBm.
Keywords : Microwave communication, line of sight (LOS), rain attenuation, rain intensity, performance
deterioration.
PACS No
: 94.10.-s
Indian J. Phys. 83 (10) 1395-1406 (2009)
Dislocation structure and microhardness of L-arginine
perchlorate single crystal
1
Tapati Mallik1, Tanusri Pal2 and Tanusree Kar1*
Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032,
India
2
Department of Physics (UG & PG), Midnapore College, Midnapore-721 101, West Bengal, India
E-mail : mstk@mahendra.iacs.res.in
Received 13 May 2008, accepted 28 April 2009
Abstract : This paper presents the chemical etching and microhardness studies carried out on L-arginine
perchlorate (LAPCl), a non-linear optical crystal (NLO) with a view to characterize the dislocation structure and
mechanical strength of the grown crystals. LAPCl crystals employed in this investigation were grown from
aqueous solution by solvent evaporation method. Optical microscopic studies of as grown habit faces revealed
formation of macrosteps and valley on (100) habit face. Chemical etching of (100) face with impurity added
organic solvents played an important role in the formation of etch pits. Selective etching of matched pairs on
opposite faces of the same plane confirms that the pits are formed at the dislocation sites. Microhardness
measurement by indentation method shows decrease of microhardness with increasing load. Nature of hardness
profile is explained with the help of Meyer’s law. The work hardening index value indicates that LAPCl belongs
to hard crystal category.
Keywords : Optical microscopy, etching, defects, growth from solutions, nonlinear optic material.
PACS Nos. : 42.70.Mp, 81.10.Dn, 62.20.-x
Indian J. Phys. 83 (10) 1407-1419 (2009)
Preparation, characterization and thermally stimulated
luminescence of ZnO nanophosphor
J Manam*, S Das and A Isaac
Department of Applied Physics, Indian School of Mines University, Dhanbad-826 004, Jharkhand, India
E-mail : jairam_manam@yahoo.co.in
Received 24 September 2008, accepted 28 April 2009
Abstract : Pure nanocrystalline ZnO thermoluminescent phosphor was synthesized by chemical
co-precipitation method. The prepared sample was characterized by XRD, SEM and FTIR. The powder samples
when exposed to X-irradiation showed that the thermoluminescence response increases linearly with the
increase of the time of X-irradiation. The glow curve exhibited two maxima centered at 116 and 207°C. The latter
glow peak displays greater stability and sensitivity when the phosphor is exposed to X-irradiation at room
temperature. The results indicate that this new ZnO phosphor is a promising detector and dosimeter for X-irradiation.
Keywords : ZnO, XRD, SEM, FTIR, thermally stimulated luminescence
PACS No.
: 78.60.Kn
Indian J. Phys. 83 (10) 1421-1438 (2009)
Normal modes and quality factors of shielded composite
dielectric spherical resonators
R A Yadav*, T K Yadav, M K Maurya, D P Yadav1 and N P Singh1
Department of Physics, Banaras Hindu University, Varanasi-221 005, Uttar Pradesh, India
1
Department of Physics, Udai Pratap Autonomous PG College, Varanasi-221 002, Uttar Pradesh, India
E-mail: rayadav@bhu.ac.in
Received on 19 December 2006, accepted 27 January 2009
Abstract : Electromagnetic field analysis of shielded composite dielectric spherical resonator in which the
dielectric sphere is composed of two concentric spheres with different dielectric materials has been made.
Characteristic equations for the TEnml and TMnml modes have been derived. From these characteristic equations,
the resonant frequencies and quality factors have been calculated using numerical method. Computations of the
resonant frequencies and quality factors have been made for resonators with parameters suitable for the optical
and microware regions.
In this paper we have presented the analysis and the results obtained from the numerical
computations for shielded composite dielectric spherical resonator in which the dielectric sphere is composed of
two concentric spheres with different dielectric materials. Starting from the Maxwell’s equations for such a
resonators have been derived and resonant frequencies and quality factor’s have been calculated for the TEnml
and TMnml modes using numerical method.
Keywords : Spherical resonators; spherical dielectric resonators; Eigen modes; quality factors.
PACS No.
: 42.50.DV
Indian J. Phys. 83 (10) 1439-1455 (2009)
Heat and mass transfer on unsteady three-dimensional
convective MHD flow past a porous plate moving in a
parallel free stream
K D Singh* and Alphonsa Mathew
Department of Mathematics (ICDEOL), Himachal Pradesh University, Shimla-171 005, Himachal Pradesh, India
E-mail : kdsinghshimla@gmail.com
Received 22 October 2008, accepted 28 April 2009
Abstract : The unsteady three-dimensional convective flow of a viscous incompressible, electrically
conducting fluid over a vertical, insulated, porous surface moving in a parallel free stream has been investigated,
which flows belong to a separate class of problem of boundary layer theory. The effects of heat and mass
transfer on this unsteady laminar flow past porous surface with transverse sinusoidal suction and oscillatory
wall temperature have been analysed and discussed.
Keywords : MHD flow, heat and mass transfer, free convection, porous plate, viscous incompressible fluid.
PACS Nos. : 47.35.Tv, 47.56.t8, 44.30.t8
Indian J. Phys. 83 (10) 1457-1461 (2009)
Reduced sized dual frequency microstrip antenna
1
2
S Bhunia1 and P P Sarkar2*
Academy of Technology, Hooghly-712 121, West Bengal, India
University Science Instrumentation Centre, University of Kalyani, Kalyani-741 235, Nadia, West Bengal, India
E-mail : parthabe91@yahoo.co.in
Received 24 October 2008, accepted 15 May 2009
Abstract : A novel, compact, single probe-feed square microstrip patch antenna for operation in dual frequency
can be achieved by cutting unequal finger like rectangular slots perpendicular to the radiating edges. From the
experimental results obtained, the proposed antenna is about 67% smaller compared to a traditional rectangular
patch operating at the same frequency and we have got the dual frequency operation in two different bands i.e.
L and S bands.
Keywords : Microstrip patch antenna, dual frequency.
PACS No.
: 84.40.Ba
Indian J. Phys. 83 (10) 1463-1485 (2009)
Azimuthal correlation and fractal study of compound
hadrons (pions and protons) at Dubna and SPS energy
Dipak Ghosh*, Argha Deb, Subrata Biswas, Pasupati Mandal,
Asok Kumar Mallick and Prabir Kumar Haldar
Department of Physics, Nuclear and Particle Physics Research Centre, Jadavpur University,
Kolkata-700 032, India
E-mail : dipakghosh_in@yahoo.com
Received 18 July 2007, accepted 9 February 2009
Abstract : This paper presents an investigation of compound hadrons (pions and protons) distribution
emitted from 24Mg-AgBr and 12C-AgBr interactions both at 4.5 AGeV and 32S-AgBr interactions at 200 AGeV. The
study includes azimuthal correlations (two particle and three particle), azimuthal asymmetry and fractal behaviour.
This paper reveals some interesting results.
Keywords : Relativistic and ultra-relativistic nucleus-nucleus interactions, compound hadrons, correlations,
azimuthal asymmetry and fractal behaviour.
PACS Nos. : 25.75.-q, 24.60.Ky
Indian J. Phys. 83 (10) 1487-1493 (2009)
Note
Impact of eigenvalues on the pseudopotential calculation of
superconducting parameters of metals Ga, Cd and In
Jayprakash Yadav*, S M Rafique and Shanti Kumari
University Department of Physics, T M Bhagalpur University, Bhagalpur-812 007, Bihar, India
E-mail : dr.jp_yadav@yahoo.co.in
Received 23 October 2008, accepted 24 April 2009
Abstract : In the present paper some superconducting (SC) state parameters of metals Ga, Cd and In have
been studied through Harrison’s First Principle [HFP] pseudopotential technique using McMillan’s formalism. The
impact of choosing two different sets of core energy eigenvalues viz. Herman-Skillman and Clementi (or
Experimental) has been studied.
It has been observed that the choice of eigenvalues has appreciable impact on the form factor and
consequently on the SC state transition parameter viz. electron-phonon coupling strength (l) and superconducting
transition temperature Tc. Hence the choice of suitable eigenvalues is essential for these computations. Reasonable
agreement with experimental and theoretical data have been obtained.
Keywords : Superconductivity, pseudopotential, multivalent metals.
PACS No.
: 74.20.-z