Botha, E C; Odendaal, J W; Geggus, K M(Microwave and Optical Technology Letters, February 20, 1998)
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Abstract:
Compact-range radar backscatter measurements are taken
of aircraft scale models. In addition, computer software is used to predict
the RCS of the aircraft. Synthetic down-range profiles formed from the
two sources of backscatter data are compared and visualized in an
innovative manner. Similar discrimination rates between the two aircraft
are obtained on data from both source
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
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
A novel optical add-drop multiplexer (OADM) based on
the Mach-Zelauler interferometer (MZI) and the fiber Bragg grating
(FBG) is proposed for the first tittle to the authors ' knowledge. In the
structure, the Mach-Zehnder interferometer acts as an optical switch.
The principle of the OADM is analyzed in this paper. The OADM can
add/drop one of the multi-input channels or pass the channel directly by
adjusting the difference of the two arms of the interferometer. The channel
isolation is more than 20 dB
Jacob,George; Aanandan,C K; Mohanan, P; K G Nair(IEEE Journals/ Transactions (USA), 1998)
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Abstract:
A new compact micro strip antenna element is analyzed.
The analysis can accurately predict the resonant frequency,
input impedance, and radiation patterns. The predicted results
are compared with experimental results and excellent agreement
is observed . These antenna elements are more suitable in applications
where limited antenna real estate is available
Huo,Y; Taylor,G W(Microwave and Optical Technology Letters, May 20, 2003)
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Abstract:
The operation of a previously proposed terahertz (THZ)
detector is formulated in detail. The detector is based on the hot-electron
effect of the 2D electron gas (2DEG) in the quantum well (QW) of
a GaAs/AIGaAs heterostructure. The interaction between the THz radiation
and the 2DEG, the current enhancement due to hot -electron effect, and
the noise performance of the detector are analyzed
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
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
Tennant,A; Dawoud,M M; Anderson,A P(Department of Electronics, April 27, 1994)
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Abstract:
A genetic algorithm has been used for null steering in phased and
adaptive arrays . It has been shown that it is possible to steer the
array null s precisely to the required interference directions and to
achieve any prescribed null depths . A comparison with the results
obtained from the analytic solution shows the advantages of using
the genetic algorithm for null steering in linear array patterns
Mohanan, P; Aanandan,C K; K G Nair(Indian Journal of Radio & Space Physics, February , 1984)
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Abstract:
A modified H-plane sectoral horn antenna with identical E- and'H- plane.patterns over the X-band frequency is discussed.
This system has significantly reduced side lobes and hack lobes. Half=power beam width and gain of the antenna are also
improved with enhanced matching , Experimental results for a number of horns with various flanges are presented . These find
practical application for illuminating symmetric antennas like paraboloids and polarization measurements in radio
astronomy, etc. Compared to the fixed pyramidal horns. the present system offers great convenience in trimming the antenna
characteristics
Mohanan, P; Pravinkumar,P A; K G Nair(Indian Journal of Radio & Space Physics, 1982)
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Abstract:
A simple technique for obtaining identical E- and H-plane patterns from E-plane sectoral feed horn is presented. Halfpower
beam width and gain of the antenna are also improved considerably. Experimental results for a number of horns with
flanges of various parameters are also presented. This system may find practical application in radar and space communication
systems
Ajaikumar,V; Jose,K A; Aanandan,C K; Mohanan, P; K G Nair(Microwave and Optical Technology Letters, October , 1992)
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Abstract:
Reduction of radar cross -section of dihedral corner reflectors using
simulated corrugated surface (.SCS) is reported. This technique is
found lo be more effective in the reduction of RCS or corner reflectors
for normal incidence . A typical reduction of 40-50 dB is
achieved using this method
A new microwave dielectric resonator Ba(Tb1/2Nb1/2)03 has been prepared and characterized in the microwave frequency region. 1 wt% CeO2 is used as additive to reduce the sintering temperature. The sintered samples were characterized by XRD, SEM and Raman spectroscopic methods. Microwave DR properties such as er, Q factor and temperature-coefficient of resonant frequency (Ti) have been measured using a HP 8510 B Network Analyzer. Cylindrical DRs of Ba(Tb1/2Nbi/2)03 showed high Er (~ 37), high Q (~3,200) and low Tf (~10 ppm /°C) at 4 GHz and hence are useful for practical applications
Bijumon, P V; Sreedevi, Menon K; Suma,M N; Sebastian,M T; Mohanan, P(IEE Electronics letters,UK, March 31, 2005)
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Abstract:
The impedance bandwidth of a high permittivity cylindrical dielectric
resonator antenna excited by a micro strip line was significantly
improved by modifying the feed geometry. The 10 dB return loss
bandwidth is enhanced from 12 to 26% without much affecting the
gain and other radiation properties of the antenna. Good agreement
has been observed between the predicted and measured results
Deepukumar,M; George,J; Aanandan,C K; Mohanan, P; K G Nair(IEE Electronics letters,UK, June 19, 1996)
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Abstract:
A new dual port microstrip antenna geometry for dual frequency
operation is presented. The structure consists of the intersection
of two circles of the same radius with their centres displaced by a
small fraction of the wavelength . This antenna provides wide
impedance bandwidth and excellent isolation between its ports.
The gain of the antenna is comparable to that of a standard
circular microstrip antenna operating at the same resonant
frequency. A theoretical analysis for calculating the resonant
frequencies of the two ports is also presented
Aanandan,C K; Mohanan, P; K G Nair(IEEE Journals/ Transactions (USA), 1990)
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Abstract:
A microstrip antenna with large bandwidth is developed
using a parasitic technique . Compared to the available
wide-baud antennas,the proposed antenna structure is very
compact and gives a lessdistorted radiation pattern with frequency .
An impedance bandwidth,eight times that of a conventional patch
antenna of the same size, Isachieved. The concept of coupled microstrip
line model Is extended fortheoretical interpretation of the impedance loci
Wang,Wel; Sheng,Bing Chen; Shun,Shi Zhong(Microwave and Optical Technology Letters, October 20, 2004)
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Abstract:
A novel slope -strip feeding technique for a microstrip
antenna is presented in order to achieve a broad bandwidth. The experimental
results show that the optimal bandwidth attained is 53.4% for
less than -10-dB return loss
Mridula, S; Sreedevi, Menon K; Mohanan,K; Bijumon, P V(Microwave and Optical Technology Letters, February 20, 2004)
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Abstract:
The radiation characteristics of a microstrip-line-excited rectangular dielectric resonator antenna (DRA) are studied experimentally.The radiation charactristics and excitation of different modes are highly influenced by the orientation of the DR,feed line parameters ,and finite size of the ground plane
Manju,Paulson; Mohanan, P; Sona,Kundukulam O(Microwave and Optical Technology Letters, September 5, 2000)
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Abstract:
A compact microstrip antenna with circular polarization radiation is demonstrated.A reducation in the required parameters for achieving CP radiation makes the present antenna design simpler
Xiong,X Z; Fusco,V F(Microwave and Optical Technology Letters, August 5, 2002)
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Abstract:
In this Letter a new physical model for metal-insulatormetal
CMOS capacitors is presented. In the model the parameters of the
circuit are derived from the physical structural details. Physical behaviors
due to metal skin effect and inductance have been considered. The
model has been confirmed by 3D EM simulator and design rules proposed.
The model presented is scalable with capacitor geometry, allowing
designers to predict and optimize quality factor. The approach has
been verified for MIM CMOS capacitors