Mohanan, T(American Institute of Physics, August 22, 2005)
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Abstract:
The effect of dopants with different valencies and ionic radii on the densification, structural
ordering, and microwave dielectric properties of Ba(Mg1/3Ta2/3)O3 (BMT) is investigated. It is
found that dopants such as Sb2O5, MnO, ZrO2, WO3, and ZnO improve the microwave dielectric
properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric
properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic
radii of the dopant has been established. The variation of the dielectric properties of pure and doped
BMT at cryogenic temperatures is also discussed.
Surendran,K P; Sebastian,M T; Mohanan, P; Mohanan,Jacob V(American Institute of Physics, 2005)
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Abstract:
The effect of dopants with different valencies and ionic radii on the densification, structural
ordering, and microwave dielectric properties of Ba(Mg1t3Tazt3)O3 (BMT) is investigated. It is
found that dopants such as Sb,05, MnO, ZrO,, WO1, and ZnO improve the microwave dielectric
properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric
properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic
radii of the dopant has been established. The variation of the dielectric properties of pure and doped
BMT at cryogenic temperatures is also discussed
The effect of glass additives on the densification , phase evolution, microstructure and microwave dielectric properties of Ba(Mg1;3
Ta2i3)03 (BMT) was investigated . Different weight percentages of quenched glass such as B203 , Si02, B203-SiO2, ZnO-B203,
5ZnO-2B2O3, Al203-SiO2, Na20-2B203.10H20, BaO-B203-SiO2, MgO-B203-SiO2, PbO-B203-SiO2 , ZnO-B203-SiO2 and
2MgO-Al203-5SiO2 were added to calcined BMT precursor . The sintering temperature of the glass -added BMT samples were
lowered down to 1300 °C compared to solid-state sintering where the temperature was 1650 °C. The formation of high temperature
satellite phases such as Ba5Ta4O15 and Ba7Ta6O22 were found to be suppressed by the glass addition . Addition of glass systems such
as B203, ZnO-B203, 5ZnO-2B203 and ZnO-B203-SiO2 improved the densification and microwave dielectric properties. Other
glasses were found to react with BMT to form low-Q phases which prevented densification . The microwave dielectric properties of
undoped BMT with a densification of 93 . 1 % of the theoretical density were Cr = 24 . 8, Tr = 8 ppm/°C and Q„ x f= 80,000 GHz. The
BMT doped with 1.0 wt% of B203 has Q„ x f = 124,700GHz, Cr = 24.2, and T f = -1.3 ppm /°C. The unloaded Q factor of 0.2 wt%
ZnO-B203-doped BMT was 136,500 GHz while that of 1.0 wt% of 5ZnO-2B203 added ceramic was Q„ x f= 141,800 GHz . The best
microwave quality factor was observed for ZnO -B203-SiO2 (ZBS) glass-added ceramics which can act as a perfect liquid-phase
medium for the sintering of BMT. The microwave dielectric properties of 0.2wt% ZBS-added BMT dielectric was
Q„ x f= 152,800 GHz, F,= 25.5, and Tr = - 1.5 ppm/°C
Sarin, V P; Nishamol, M S; Gijo,Augustin; Mohanan, P; Aanandan,C K; Vasudevan, K(John Wiley & Sons, July , 2008)
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Abstract:
A new design of a dual-band dual-polarized electromagnetically coupled slot loaded square patch antenna, covering the WLAN 5.2 GHz and 5.8 GHz bands, achieving bandwidth enhancement by using tapered slot structure, is presented here. The proposed antenna covers 5.09–5.47 GHz and 5.7–5.88 GHz bands. Details of the antenna design along with experimental and simulated results are presented and discussed.
In this paper, a dual port, dual frequency, dual polarized,
octagonal shaped Microstrip patch antenna, suitable for GPS
applications is discussed experimentally and theoretically. The
proposed antenna configuration is characterized by good
impedance bandwidth, gain, isolation between two ports and
broad radiation patterns
Description:
Personal Wireless Communications, 2005. ICPWC 2005. 2005 IEEE International Conference on,PP 305-307
A new localization approach to increase the navigational
capabilities and object manipulation of autonomous
mobile robots, based on an encoded infrared sheet of light
beacon system, which provides position errors smaller than
0.02m is presented in this paper. To achieve this minimal
position error, a resolution enhancement technique has
been developed by utilising an inbuilt odometric/optical
flow sensor information. This system respects strong low
cost constraints by using an innovative assembly for the
digitally encoded infrared transmitter. For better guidance
of mobile robot vehicles, an online traffic signalling capability
is also incorporated. Other added features are its less
computational complexity and online localization capability
all these without any estimation uncertainty. The
constructional details, experimental results and computational
methodologies of the system are also described
Description:
Journal of Automation, Mobile Robotics & Intelligent Systems VOLUME 3, N° 2 2009
Bijumon, P V; Sreedevi, Menon K; Sebastian,M T; Mohanan, P(Microwave and Optical Technology Letters, November 20, 2002)
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Abstract:
A novel technique fitr the bat dividth enhancement of conventional
rectangular microstrip antenna is proposed in this paper. When a
high permittivity dielectric resonator of suitable resonant frequency was
loaded over the patch. the % bandwidth of the antenna was increased by
more than five tunes without much affecting its gain and radiation performance.
A much more improved bandwidth was obtained when the dielectric
resonator was placed on the feedline. Experimental study shows a 2:1
VSWR bandwidth of more than 10% and excellent cross polarization performance
with increased pass band and radiation coverage abnost the same
as that of rectangular microstrip antenna
Tessamma, Thomas; Nobert, Thomas Pallath; Suresh, S(February , 2014)
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Abstract:
In this paper the effectiveness of a novel method of computer assisted pedicle screw insertion was studied using testing of hypothesis procedure with a sample size of 48. Pattern recognition based on geometric features of markers on the drill has been performed on real time optical video obtained from orthogonally placed CCD cameras. The study reveals the exactness of the calculated position of the drill using navigation based on CT image of the vertebra and real time optical video of the drill. The significance value is 0.424 at 95% confidence level which indicates good precision with a standard mean error of only 0.00724. The virtual vision method is less hazardous to both patient and the surgeon
Description:
International Journal of Scientific and Research Publications, Volume 4, Issue 2, February 2014
Lo, H Y; Leung, K W(Microwave and Optical Technology Letters, June 5, 2001)
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Abstract:
A new configuration that employs a conducting conformal
strip to excite the low-profile equilaterial-triangular dielectric resonator
antenna (DRA) of very high permittivity is proposed. As compared with
the previous aperture-coupling configuration, the new configuration has
a wider impedance bandwidth (- 5.5%) and a higher front-to-back
radiation ratio. The return loss, radiation patterns, and antenna gain are
measured and discussed
Hunagund,P V; Jose,K A; Mohanan, P; Nair, K G(Indian Journal of Radio & Space Physics, February , 1992)
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Abstract:
Results of exhaustive study of the effect of metallic flanges on H-plane radiation characteristics of V-slot
waveguide antenna are presented . It has been established that the beam can be sharpened or broadened by
varying the flange angle . The adjustment of the flange angle and flange width would further improve the
radiation pattern , yielding optimum efficiency from the flanged system
The presence of microcalcifications in mammograms can be considered as an early indication of breast cancer. A fastfractal block coding method to model the mammograms fordetecting the presence of microcalcifications is presented in this paper. The conventional fractal image coding method takes enormous amount of time during the fractal block encoding.procedure. In the proposed method, the image is divided intoshade and non shade blocks based on the dynamic range, andonly non shade blocks are encoded using the fractal encodingtechnique. Since the number of image blocks is considerablyreduced in the matching domain search pool, a saving of97.996% of the encoding time is obtained as compared to theconventional fractal coding method, for modeling mammograms.The above developed mammograms are used for detectingmicrocalcifications and a diagnostic efficiency of 85.7% isobtained for the 28 mammograms used.
Description:
IEEE-International Conference on Signal processing, Communications and Networking
Madras Institute of Technology, Anna University Chennai India, Jan 4-6, 2008. Pp368-373
Lethakumary,B; Sreedevi, Menon K; Aanandan,C K; Vasudevan, K; Mohanan, P(Microwave and Optical Technology Letters, November 20, 2004)
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Abstract:
A theoretical analysis of a symmetric T-shaped rnicrostripfed
rectangular microstrip antenna using the finite-difference titnedoniain
(FDTD) method is presented in this paper. The resonant frequency,
return loss, impedance bandwidth, and radiation patterns are
predicted and are in good agreement with the measured results
The paper presents a maximally flat compact
planar filter employing folded Stepped Impedance
Resonators (SIR) and Complementary Split Ring
Resonators (CSRR), for Ultra Wide Band (UWB)
applications. An interdigital quarter wavelength coupled
line is used for achieving the band pass characteristics.
The filter has low insertion loss in its pass band and
steep roll off rate and good attenuation in its lower and
upper stop bands. The measured microwave
characteristics of the fabricated filter show good
agreement with the simulated response
Description:
Electronic System Design (ISED), 2013 International Symposium on
Mridula, S; Sumi, M; Dinesh, R; Nijas, C M; Mohanan, P(SPOLECNOST PRO RADIOELEKTRONICKE INZENYRSTVI, April , 2014)
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Abstract:
A novel compact chipless RFID tag using spurline
resonators is discussed in this paper. The detection of
the tag's ID is using the spectral signature of a spurline
resonator circuit. The tag has a data capacity of 8-bits in
the range 2.38 to 4.04 GHz. The tag consists of a spurline
multiresonating circuit and two cross polarized antennas.
The prototype of the tag is fabricated on a substrate CMET/
LK4.3 of dielectric constant 4.3 and loss tangent
0.0018. The measured results show that group delay response
can also be used to decode the tag’s identity
Chandran,A R; Mathew,T; Aanandan,C K; Mohanan, P; Vasudevan, K(Department of Electronics, September , 2004)
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Abstract:
Electromagnetic scattering behaviour of a superstrate loaded metallo–
dielectric structure based on Sierpinski carpet fractal geometry is
reported. The results indicate that the frequency at which backscattering
is minimum can be tuned by varying the thickness of the superstrate.
A reduction in backscattered power of 44 dB is obtained
simultaneously for both TE and TM polarisations of the incident field.
Negative magnetic permeability media
(NMPM) can be built up by using small resonant metallic
particles like Split ring resonator (SRR) which has very
high magnetic polarisability. A group of these particles
shows a negative permeability region near and above the
resonant frequency. The continuous medium parameters
describing the SRR array can be predicted from their
individual electromagnetic behavior near the resonances.
The paper presents an optimizing software using Genetic
Algorithm (GA) to design an edge coupled two ring SRR
for a particular frequency
Description:
Recent Advances in Microwave Theory and Applications, 2008. MICROWAVE 2008. International Conference on
A new group of compounds with composition (Ba5-xSrx) Nb4015, having high
permittivity and low loss have been prepared and characterized in the microwave
frequency region . X-ray diffraction studies showed that monophase compound
existed for all values of x from 0 to 5. Microwave dielectric properties such as
and c f showed smooth variation with x , while the unloaded quality factor (Qu)
showed remarkable improvement with x