Supriyo,Dey; Aanandan,C K; Mohanan, P; K G Nair(Microwave and Optical Technology Letters, September , 1994)
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Abstract:
A simple technique to improve the impedance bandwidth of a circular
microstrip patch antenna using two sectorial slots is proposed. Using this
design more than 5% impedance bandwidth is obtained. The added
advantage of this new antenna is that it can be fed by a 50- microstrip line
Manju,Paulson; Sona,Kundukulam O; Aanandan,C K; Mohanan, P(Microwave and Optical Technology Letters, June 5, 2001)
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Abstract:
A new compact dual-band, dual-polarized microstrip antenna
is presented. 7'iris antenna resonates at two frequencies with
different polarizations: a linearly polarized one for terrestrial
communication, and a circularly polarized one for satellite mobile
communication. This antenna also provides an area reduction of 70%
compared to a standard rectangular patch antenna
George,J; Deepukumar,M; Aanandan,C K; Mohanan, P; K G Nair(Department of Electronics, March , 1996)
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Abstract:
A new microstrip antenna geometry with considerable reduction
in size, with similar radiation characteristics to those of an
equivalent rectangular patch antenna is proposed. A relationship
has been suggested for fmding out the resonant frequency of the
new geometry, and its validity has been established by the
experimental results. Without increasing the aperture area, this
geometry also offers a facility for considerably reducing the
resonant frequency compared to conventional patches.
New dielectric ceramics with formula BaTi3Nb4, O„ and Ba6Til4Nbz039 have been prepared and characterized. BaTi3Nba017 was densified to 92% of TD after firing at 1310 oC for 4 h. However, Ba6Ti 1 4Nb2O39 fired under optimized conditions (1260 ` C for 4 h) showed only 85% TD together with secondary phase. The crystal system of both of the compositions is orthorhombic
Monz, Cabrera J; Diaz, Morcillo A; Pedreno, Molina L; Sanchez, Hermandez D(Microwave and Optical Technology Letters, February 4, 2004)
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Abstract:
Usage of a dielectric multilayer around a dielectric Sample
is studied as a means for improving the efficiency in multimode microwave-
heating cavities. The results show that by using additional dielectric
constant layers the appearance of undesired reflections at the
sample-air interface is avoided and higher power -absorption rates
within the sample and high -efficiency designs are obtained
Binu, Paul; Mridula, S; Aanandan,C K; Mohanan, P(Microwave Engineering Group,Department of Electronics, May 20, 2002)
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Abstract:
compact multihand planar octagonal-shaped microstrip
antenna simultaneously suitable for mobile communication and blue
tooth application is presented. The antenna provides sufficient isolation
benveen the two operating bands and an area reduction of -29 % with
respect to a circular patch operating in the same band
Stephen,D S; Mathew,T; Jose,K A; Aanandan,C K; Mohanan, P; K G Nair(Department of Electronics, February , 1993)
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Abstract:
Simultaneous elimination of specular reflection and backscattered
power from a plane metallic surface by simulated
corrugated surfaces of constant period and variable strip
width for TM polarisation is reported. This new configuration
offers almost a ten-fold frequency bandwidth compared
with a regularly spaced strip grating of the same size.
Abdel, Fattah Sheta(Microwave and Optical Technology Letters, April 5, 2001)
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Abstract:
A novel H-shaped patch antenna suitable for wireless and
satellite communications is presented. The new antenna has some advantages
compared to conventional microstrip patch antennas, such as
small size, a fewer number of modes, no harmonic resonance, and the
provision of pure reactive impedances at its harmonics that can result in
increasing the transmitter efficiency. The basic principles and design
procedure are introduced. Two antennas at two different frequencies, 4
and 10 GHz, are designed, fabricated, and measured. The measured
results show a good agreement with the predicted ones
Jack,Wu; Qiu,S N; Shih,I(Microwave and Optical Technology Letters, November 20, 2004)
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Abstract:
Photonic band-gap (PBG) structures are utilized in microwave
components as filters to suppress unwanted signals. In this
work, rectangular perforations were created in the ground plane of a microstrip line to construct a PBG structure. A gold-coated alumina
substrate was utilized to switch or tune the bandstop characteristics of
this structure. It was demonstrated that the bandstop characteristics
were switched off from - 35 to - 1 dB at 16 GHz. Tuning of the bandstop
edge with a shift of 1.5 GHz was also shown
Qiang,Gao; Yan,Yin; Dun-Bao,Yan; Nai,Chang Yuan(Microwave and Optical Technology Letters, November 5, 2005)
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Abstract:
A navel ultra-thin radar-absorbing material (RAM) using
metanwterials is presented and the absorption performance is examined.
Due to the high-impedance property of the metamalerials. the thickness
of the RAM is about several tenths of the center wavelength of the absorption
band, which is considerably thinner than conventional absorbers.
The absorption bandwidth of the RAM is about several hundred
megahertz
Supriyo,Dey; Aanandan,C K; Mohanan, P; K G Nair(IETE Technical Review, 1993)
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Abstract:
Design, development and experimental observations of a L: band printed dipole antenna is presented.Bandwidth
enhancement is achieved by end-loading or the dipole arms. Using the present technique Impedance bandwidth van be
enhanced up to 50% without degrading the efficiency of the antenna.
Mohanan, P; Girijavallabhan, C P; Aanandan,C K; K G Nair(Indian Journal of Radio & Space Physics, February , 1984)
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Abstract:
A forward - biased point contact germanium signal diode placed inside a waveguide section along the E -vector is found to
introduce significant phase shift of microwave signals . The usefulness of the arrangement as a phase modulator for microwave
carriers is demonstrated. While there is a less significant amplitude modulation accompanying phase modulation , the insertion
losses are found to be negligible. The observations can be explained on the basis of the capacitance variation of the barrier layer
with forward current in the diode
Mridula, S; Sreedevi, Menon K; Lethakumary,B; Binu, Paul; Aanandan,C K; Mohanan, P(Microwave and Optical Technology Letters, July 20, 2002)
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Abstract:
A broadband rectangular tnicrostrip antenna utilizing
an electromagnetically coupled L-strip feed is presented. Experimental
study shows a 2:1 VSWR bandwidth of a 10% and excellent
cross-polarization performance with a radiation coverage almost as
same as that of the rectangular microstrip antenna fed by conventional
methods. The variation of bandwidth for different feed parameters is also studied. The proposed antenna is suitable for broadband
communications
Haskins, P M; Dahele, J S(Department of Electronics, March 14, 1996)
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Abstract:
Two three-clement polarisation-agile active microstrip patch
arrays have been developed . The radiating elements are square
patches each with two transistors mounted on adjacent edges. The
patches radiate orthogonal modes , the relative phase of which can
be varied. Radiation patterns show good agreement with
predictions from theory, in both linear and circular polarization,
and no grating lobes were observed
Sangster,A J(Microwave and Optical Technology Letters, September , 1991)
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Abstract:
A new microstrip antenna element is described which exhibits polarization
agility. This is achieved by employing a T-slot radiator
which is driven by the edge fields of a balanced microstrip line. The
balanced line can support two propagating modes. namely. an even
mode and an odd mode, and be switching between these modes. the
orthogonal arms of the T-slot radiator are separately excited thus
forming orthogonally polarized radiated fields. A nucrostrip patch
antenna, which displays polarization agility using the sane mechanism,
is also described
Choudhury, P K(Microwave and Optical Technology Letters, November 25, 2002)
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Abstract:
A fairly rigorous analytical treatment of the power characteristics
of dielectric optical waveguides with Piet Hein core-cross
sectional geometry is presented in this paper. This kind of wareguide
structure would be advantageous owing to the absence of corners,
which are found in rectangular guides, resulting in undesirable loss (hit
to the scattering of light. In order to simplify this theoretical approach.
em approximation of vanishing refractive index difference between the
guiding and the non-guiding sections is implemented. The variation eJ
logarithmic power is shown for different dimensions of the core, corresponding
to different azimuthal modal indices. It is found that the nutlet
with higher index values carry less logaritlunic power in the lower tail
of the propagation 's constant range, and this feature affects the higher
tail. A better kind of uniformity of the power distribution is observed
near the higher tail of the range of propagation Constants
Ceramics of composition BaO-Ln2O3-STiO2 have been prepared with four elements (Ln=La,Pr,Nd.Sm) by a conventional solid state ceramic preparation route and the dielectric properties measured in the microwave frequency range
The dielectric ceramics BaNd2Ti3Oto, BaNd2Ti4O12 and BaNd2Ti5O14 have been prepared by
Conventional solid state ceramic route. The sintered ceramic samples have been characterized by
X-ray diffraction and Scanning Electron Microscopy (SEM). The dielectric properties in the
microwave frequency range have been measured using conventional microwave dielectric
resonator methods. The BaNd2Ti1O10, BaN2Ti4O12 and BaNd2Ti5O14 have dielectric constants
(Er) ~ 60, 84 and 77 respectively. They have relatively high quality factors
Abdul Khalam,L; Sreemoolanadhan,H; Ratheesh, R; Mohanan, P; Sebastian,M T(ELSEVIER, 2003)
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Abstract:
Microwave dielectric resonators (DRs) based on Ba(B1,2Nbi/2)03 [B' = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb, and In] complex
perovskites have been prepared by conventional solid state ceramic route. The dielectric properties (relative permittivity, Er; quality factor, Q;
and resonant frequency, rr) of the ceramics have been measured in the frequency range 4-6 GHz using resonance methods. The resonators
have relatively high dielectric constant in the range 36-45, high quality factor and small temperature variation of resonant frequency. The
dielectric properties are found to depend on the tolerance factor (t), ionic radius (r), and lattice parameter (ap)
Mailadil,Sebastian T; Sam,Solomon; Ravindran,Ratheesh(Regional Research Laboratory, April , 1999)
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Abstract:
Microwave ceramic dielectric resonators (DRs) based on RETiNbO6
(RE = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Y, and Yb)
have been prepared using the conventional solid -state ceramic
route. The DR samples are characterized using XRD and SEM
methods. The microwave dielectric properties are measured
using resonant methods and a net work analyzer . The ceramics
based on Ce, Pr, Nd, and Sin have dielectric constants in the
range 32-54 and positive coefficient of thermal variation of
resonant frequency (r,). The ceramics based on Gd, Tb, Dy, Y.
and Yb have dielectric constants in the range 19-22 and
negative Tf