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
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
Hsieh,Gui-Bin; Chen,Ming-Huang; Wong,Kin-Lu Wong(IEE Electronics letters,UK, June 21, 2001)
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Abstract:
A novel technique for obtaining dual-hand circular polarization
(CP) radiation of a single-feed circular microstrip antenna in
proposed and demonstrated. By embedding two pain of arc shaped
slots of proper lengths close to the boundary of a circular
patch, and protruding one of the arc-shaped slots with a narrow
slit, the circular microstrip antenna can perform dual-hand CP
radiation using a single probe feed. Details of the antenna design
A simple technique for calculating the resonance frequencies of a
compact arrow-shaped microstrip antenna is presented and discussed . The accuracy of the method is validated by experimental results
Paulson,M; Sona,Kundukulam O; Aanandan,C K; Mohanan, P(Department of Electronics, September , 2001)
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Abstract:
The arrow shaped microstrip antenna, which produces
dual frequency dual polarisation operation with considera-ble size reduction compared to conventional patches has been
reported [I]. These antennas provide greater area reduction and
improved gain compared to drum shaped patches [2]. Prediction
of the resonance frequency of drum shaped patches [3] and circular
patches for broadband operation [4] are available in the literature.
In this Letter, we propose empirical formulas for calculating
the resonance frequencies of the arrow shaped microstrip antenna.
These antennas can be employed for obtaining dual frequency
with the same polarisation, bandwidth enhancement, circular
polarisation etc. by varying its different parameters or by introducing
slots. The proposed design equations provide an easier and
simple way of predicting the resonant frequencies of these patches.
Vermeeren,G; Rogier,H; Olyslager,F; Zutter De,D(IEE Electronics letters,UK, September 13, 2001)
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Abstract:
A single-feed rectangular-ring microstrip antenna is proposed for
indoor communication under the Bluetooth protocol. The
dimensions of the antenna together with the location of the feed
point are optimized through field simulations in order to cover the
Bluetooth bandwidth and to avoid linear polarization. The
performance and the efficiency of the antenna are illustrated in a
real indoor environment
Sona,Kundukulam O; Manju,Paulson; Aanandan,C K; Mohanan, P(Microwave and Optical Technology Letters, December 5, 2001)
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Abstract:
Dual frequency operation is achieved from a compact
microstrip antenna by loading a pair of narrow slots close to its radiating
edges. The two frequencies have parallel polarization planes and similar
radiation characteristics. The ratio between the two operating frequencies
can be tuned in the range (1.14-1. 24), which is much smaller than that
of similar designs. The above excellent radiation characteristics are
achieved along with an area reduction of - 75% compared to the
standard rectangular patch
Hyunkieu,Yang; Sangseol,Lee(Microwave and Optical Technology Letters, December 5, 2001)
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Abstract:
The cutoff wavenumbers of higher order modes in circular
eccentric guides are computed with the variational analysis combined
with a conformal mapping. A conformal mapping is applied to the
variational formulation, and the variational equation is solved by the
finite-element method. Numerical results for TE and TM cutoff
wavenumbers are presented for different distances between the centers
and ratio of the radii. Comparisons with numerical results found in the
literature validate the presented method
Microwave dielectric ceramics based on RETiTaO6 (RE = La, Cc, Pr, Nd, Sm, Eu,
Gd, Tb, Dy, Ho, Y, Er, Yb, Al, and In) were prepared using a conventional solid-state
ceramic route. The structure and microstructure of the samples were analyzed using
x-ray diffraction and scanning electron microscopy techniques. The sintered samples
were characterized in the microwave frequency region. The ceramics based on Ce, Pr,
Nd, Sm, Eu, Gd, Tb, and Dy, which crystallize in orthorhombic aeschynite structure,
had a relatively high dielectric constant and positive T f while those based on Ho, Er,
and Yb, with orthorhombic euxenite structure, had a low dielectric constant and
negative Tf. The RETiTaO6 ceramics had a high-quality factor. The dielectric constant
and unit cell volume of the ceramics increased with an increase in ionic radius of the
rare-earth ions, but density decreased with it. The value of Tf increased with an
increase in RE ionic radii, and a change in the sign of Tf occurred when the ionic
radius was between 0.90 and 0.92 A. The results indicated that the boundary of the
aeschynite to euxenite morphotropic phase change lay between DyTiTaO6 and
HoTiTaO6. Low-loss ceramics like ErTiTaO6 (Er = 20.6, Qxf = 85,500), EuTiTaO6
(Er = 41.3, Qxf = 59,500), and YTiTaO6 (Er = 22.1, Q„xf = 51,400) are potential
candidates for dielectric resonator applications
Pazhoor Bijumon, Varghese; Mohanan, P; Mailadil, Thomas Sebastian(The Japan Society of Applied Physics, 2002)
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Abstract:
Microwave ceramic dielectric materials Ca5Nb2TiO12 and Ca5Ta2TiO12 have been prepared by a conventional solid-state
ceramic process. The structure was studied by X-ray diffraction and the dielectric properties were characterized at microwave
frequencies. The ceramics posses a relatively high dielectric constant, very low dielectric loss (Q5 x f > 30000GHz) and
small temperature variation of resonant frequency. These materials are potential candidates for dielectric resonator
applications in microwave integrated circuits. [DOI: 10. 1 143/JJAP.41.3834]
The microwave dielectric properties of (I -x)CaTiO3-xSm(Mg1/2Tit,2)O3(0.1 <-x< 1.0) have been investigated. The
system forms a solid solution throughout the entire compositional range. The dielectric constant decreases from 86 to 25 as x
varies from 0.1 to 1.0. The Qxf varies non-linearly and increases for composition with x> 0.6. The nonmonotonic variation
with composition x is more pronounced in Tt than in er. The microwave dielectric properties indicate the possibility of a phase
transformation for x between 0.4 and 0.5
Zhongyou,Yan(Microwave Engineering Group,Department of Electronics, January 5, 2002)
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Abstract:
patch resonator with a via connecting ground plane is
proposed and studied experimentally. The resonant frequency of this
patch resonator is tunable up to about 34 % by adjusting the via position
in the center line. The lowest resonant frequency of this patch resonator
has been reduced by more than 64% of the same size patch resonator
Binoy,G S; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave Engineering Group,Department of Electronics, January 5, 2002)
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Abstract:
A novel dual frequency design of a square microstrip antenna coaxially
fed along the diagonal with a chip capacitor mounted at the bottom of
the stub is introduced. This design provides enhanced area reduction and
good cross-polarization levels. The antenna design can be used as a compact
antenna system where limited size is a major requirement. The details of the
antenna design and experimental results are presented
Binoy,G S; Aanandan,C K; Mohanan, P; Vasudevan, K(International Journal of Electronics, January 12, 2002)
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Abstract:
A new design of' a dual-frequency dual-polarized square microsh'ip antenna fed
along the diagonal, embedded with a square slot having three extended stubs for
frequency tuning, is introduced. The proposed antenna was fabricated using a
standard photolithographic method and the antenna was tested using the HP
3510(:; Vector Network Analyser. The antenna is capable of generating dual
resonant frequencies with mutually perpendicular polarizations and broad
radiation pattern characteristics. Such dual-frequency designs find wide
applications in personal mobile handsets combining GSM and CDS 1800 modes,
and applications in which different frequencies are used for emission and reception
such as personal satellite communications and cellular network systems.
Manju,Paulson; Sona,Kundukulam O; Aanandan,C K; Mohanan, P(Microwave and Optical Technology Letters, January 20, 2002)
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Abstract:
A dual-port dual-polarized compact microstrip antenna
for avoiding cross coupling between the two frequency bands is proposed
and analyzed. This antenna offers channel isolation better than 25 dB,
and is more compact compared to a conventional rectangular patch.
Analytical equations for calculating the resonant frequencies at both
ports are also presented. The theoretical calculations are verified using
experimental results
Choudhury, P K; Roger, Lessard S(Microwave and Optical Technology Letters, January 20, 2002)
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Abstract:
An attempt is made to determine the relative power
distribution in a step-index parabolic cylindrical waveguide (PCW) with
high deformation across the direction of propagation. The guide is
assumed to be made of silica. The scalar field approximation is employed
for the analysis under which a vanishing refractive-index (RI) difference
in the waveguide materials is considered. Further, no approximation for
folds- is used in the analytical treatment. Due to the geometry of such
waceguides, PCWs lose the well-defined modal discreteness, and a kind
of mode bunching is observed instead, which becomes much more
prominent in PCWs with high bends. However, with the increase in
cross-sectional size, the mode-bunching tendency is slightly reduced. The
general expressions for power in the guiding and nonguiding sections are
obtained, and the fractional power patterns in all of the sections are
presented for PCWs of various cross-sectional dimensions. It is observed
that the confinement of power in the core section is increased for PCWs
of larger cross-sectional size. Moreover, a fairly uniform distribution of
power is seen over the modes having intermediate values of propagation
constants
Sona,Kundukulam O; Manju,Paulson; Aanandan,C K; Mohanan, P(Microwave Engineering Group,Department of Electronics, April 20, 2002)
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Abstract:
Design equations are presented for calculating the resonance frequencies for a
compact dual frequency arrow-shaped microstrip antenna. This provides a fast and simple
way to predict the resonant frequencies of the antenna. The antenna is also analyzed using the
IE3D simulation package. The theoretical predictions are found to be very close to the
IE3D results and thus establish the validity of the design formulae
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
Donghyun,Kim; Sangseol,Lee(Microwave and Optical Technology Letters, July 20, 2002)
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Abstract:
Most adaptive linearization circuits for the nonlinear amplifier
have a feedback loop that returns the output signal oj'tne eunplifier
to the lineurizer. The loop delay of the linearizer most be controlled
precisely so that the convergence of the linearizer should be assured lot
this Letter a delay control circuit is presented. It is a delay lock loop
(ULL) with it modified early-lute gate and can he easily applied to a
DSP implementation. The proposed DLL circuit is applied to an adaptive
linearizer with the use of a polynomial predistorter, and the simulalion
for a 16-QAM signal is performed. The simulation results show that
the proposed DLL eliminates the delay between the reference input signal
and the delayed feedback signal of the linearizing circuit perfectly,
so that the predistorter polynomial coefficients converge into the optimum
value and a high degree of linearization is achieved
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