Sreedevi, Menon K; Vasudevan, K; Aanandan,C K; Mohanan, P(Microwave and Optical Technology Letters, September 20, 2005)
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Abstract:
Propagation of electromagnetic waves through a microstrip
line with 2D electromagnetic baud gap (EBG) structures of different
geometrical shapes in the ground plane is investigated in this paper.
Using transmission-line theory, the design equations for EBG structures are calculated. The measured, numerical. and simulated results are in
gone) agreement
James, Kurian; Subramaniam, M P; Saseendran Pillai, P R(IEEE, September 22, 2003)
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Abstract:
For the scientific and commercial utilization of Ocean resources, the role of
intelligent underwater robotic systems are of great importance. Scientific activities like
Marine Bio-technology, Hydrographic mapping, and commercial applications like Marine
mining, Ocean energy, fishing, aquaculture, cable laying and pipe lining are a few utilization
of ocean resources. As most of the deep undersea exploration are beyond the reachability of
divers and also as the use of operator controlled and teleoperated Remotely Operated Vehicles (ROVs)
and Diver Transport Vehicles (DTVs) turn out to be
highly inefficient, it is essential to have a fully
automated system capable providing stable control
and communication links for the unstructured
undersea environment.
Zachariah,E J; Vasudevan, K; Pravinkumar,P A; Mohanan, P; K G Nair(Indian Journal of Radio & Space Physics, February , 1984)
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Abstract:
The design, erection and evalution procedures for it microwave anechuic chamber competed at Cochin University for
antenna studies are presented the chamber has an average reflectivity level of - 32 dB on at X-band frequencies, and it i,
comparable to international standards.
In this paper the design issues of compact genetic microstrip antennas for mobile
applications has been investigated. The antennas designed using Genetic Algorithms
(GA) have an arbitrary shape and occupies less area (compact) compared to the
traditionally designed antenna for the same frequency but with poor performance. An
attempt has been made to improve the performance of the genetic microstrip antenna by
optimizing the ground plane (GP) to have a fish bone like structure. The genetic antenna
with the GP optimized is even better compared to the traditional and the genetic antenna.
Description:
Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE
A compact microstrip multiband antenna on a
modified ground plane which can operate over the bands starting
from 900 MHz to 5.35 GHz which includes the GSM (880-960)
GPS (1568-1592 MHz), DCS (1710-1880 MHz), and PCS (1850-
1990 MHz). UMTS (1920-2170 MHz), IEEE 802.11 b/g (2400-
2484) and WLAN IEEE 802.11a band (5.15-5.35) is reported in
this paper. The overall dimension of the antenna is 33 x 33 mm2
including the top patch with a dimension 22 x 22 mm2. The
experimental results of the antenna are presented in this paper.
The results confirm that the antenna exhibits wide band
characteristics and covers 7 bands of operation
Gopikrishna, M; Deepti Das, Krishna; Aanandan,C K; Mohanan, P; Vasudevan, K(Wiley InterScience, April , 2009)
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Abstract:
The design and performance of a stepped slot printed monopole antenna in the ultrawideband is presented in this article. Multiple resonances generated by the stepped slot geometry are matched in the ultrawideband using a modified microstrip feed. The impedance bandwidth (SWR < 2) of the antenna is from 3 to 11 GHz. Radiation patterns are stable and omnidirectional with appreciable gain throughout the band. Performance of the antenna is also analyzed in the time domain, which reveals good pulse handling capabilities. Compact geometry of the antenna allows easy commercial deployment.
Mridula, S; Anju, Pradeep; Mohanan, P(IEEE, August , 2011)
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Abstract:
Electric permittivity and magnetic permeability control electromagnetic wave propagation th rough materials. I n naturally
occu rring materials, these are positive. Artificial materials exhi b iting negative material properties have been reported :
they are referred to as metamaterials. This paper concentrates on a ring-type split-ring resonator (SRR) exhibiting
negative magnetic permeability. The design and synthesis of the SRR using the genetic-algorithm approach is explained
in detail. A user-friendly g raphical user i nterface (G U I ) for an SRR optim izer and estimator using MATLAB TM is also
presented
Description:
IEEE Antennas and Propagation Magazine, Vol. 53, No. 4, August 20 1 1
Mridula, S; Binu, Paul; Mythili, P; Mohanan, P(Wiley Subscription Services, Inc., A Wiley Company, December , 2010)
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Abstract:
A method for simultaneously enhancing the bandwidth
and reducing the size of microstrip antennas (MSAs) using a modified
ground plane (GP) has been proposed with design formulas. A combshaped
truncated GP is used for this purpose. This method provides an
overall compactness up to 85% for proximity-coupled MSAs in the
frequency range of 900 MHz–5.5 GHz with an improvement inbandwidth up to seven times when compared with the conventional ones
Description:
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 52, No. 12, December 2010
Shynu, S V; Gijo,Augustin; Aanandan,C K; Mohanan, P; Vasudevan, K(Progress In Electromagnetics Research, 2006)
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Abstract:
The design of a compact, single feed, dual frequency
dual polarized and electronically reconfigurable microstrip antenna is
presented in this paper. A square patch loaded with a hexagonal slot
having extended slot arms constitutes the fundamental structure of
the antenna. The tuning of the two resonant frequencies is realized by
varying the effective electrical length of the slot arms by embedding
varactor diodes across the slots. A high tuning range of 34.43%
(1.037–1.394 GHz) and 9.27% (1.359–1.485 GHz) is achieved for the
two operating frequencies respectively, when the bias voltage is varied
from 0 to −30 V. The salient feature of this design is that it uses no
matching networks even though the resonant frequencies are tuned in
a wide range with good matching below −10 dB. The antenna has an
added advantage of size reduction up to 80.11% and 65.69% for the two
operating frequencies compared to conventional rectangular patches.
Mathew, K T; Anil, Lonappan; Paul, Benzy; Thimothy, V O; Rajasekaran, C; Vinu, Thomas; Joe, Jacob(Wiley InterScience, January , 2009)
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Abstract:
This article reports a new in vitro bile analysis based on
the measurement of the dielectric properties at microwave frequencies.
The measurements were made using rectangular cavity perturbation
technique at the S-band of microwave frequency with the different samples
of bile obtained from healthy persons as well as from patients. It is
observed that an appreciable change in the dielectric properties of patient’s
samples with the normal healthy samples and these measurements
were in good agreement with clinical analysis. These results prove an
alternative in-vitro method of detecting bile abnormalities based on the
measurement of the dielectric properties of bile samples using microwaves
without surgical procedure.
Bagei, A M; Cetin, A E(IEE Electronics letters,UK, October 24, 2002)
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Abstract:
A method for computer- aided diagnosis of micro calcification clusters
in mammograms images presented . Micro calcification clus.eni which
are an early sign of bread cancer appear as isolated bright spots in
mammograms. Therefore they correspond to local maxima of
the image. The local maxima of the image is lint detected and they
are ranked according to it higher-order statistical test performed over
the sub band domain data
Shynu, S V; Gijo,Augustin; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave and Optical Technology Letters, August 20, 2005)
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Abstract:
A new design for a compact electronically reconffgurable
singlefeed dual frequency dual-polarized operation of a square-microstrip
antenna capable of achieving tunable frequency ratios in the range
1.1 to 1.37 is proposed and experimentally studied. Varactor diodes inlegruted
with the arms of the hexagonal slot and embedded in the
square patch are used to tune the operating frequencies by applying
reverse-bias voltage. The design has the advantage of size reduction up
to 73.21% and 49.86% for the two resonant frequencies, respectively, as
compared to standard rectangular patches. The antenna offers good
bandwidth of 5.74% and 5.36% for the two operating frequencies. A
highly simplified tuning circuitry without any transmission lines adds to
the compactness of the design
Jacob,George; Aanandan,C K; Mohanan, P; K G Nair; Sreemoolanathan,H; Sebastian,M T(Microwave and Optical Technology Letters, February 20, 1998)
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Abstract:
A new method for enhancing the 2.1 VSWR impedance
bandwidth of microstrip antennas is presented. Bandwidth enhancement
is achieved by loading the microstrip antenna by a ceramic microwave
dielectric resonator (DR). The validity of this technique has been established
using rectangular and circular radiating geometries. This method
improves the bandwidth of a rectangular microstrip antenna to more
than 10% (= 5 times that of a conventional rectangular microstrip
antenna) with an enhanced gain of I dB
Ceramic dielectrics with high dielectric constant in the microwave frequency range are used as filters, oscillators [I], etc. in microwave integrated
circuits (MICs) particularly in modern communication systems like cellular telephones and
satellite communications. Such ceramics, known as 'dielectric resonators (DRs),donot
only offer miniaturisation and reduce the weight of the microwave components. but also
improve the efficiency of MICs
Biju Kumar, S; Mathew, K T; Raveendranath, U; Augustine,P(lnternational Microwave Power Institute, 2001)
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Abstract:
In the medical field, microwaves play a larger role for treatment than diagnosis. For the detection of diseases by microwave methods, it is essential to know the dielectric properties of biological materials. For the present study, a cavity perturbation technique was employed to determine the dielectric properties of these materials. Rectangular cavity resonators were used to measure the complex permittivity of human bile, bile stones, gastric juice and saliva. The measurements were carried out in the S and J bands. It is observed that normal and infected bile have different dielectric constant and loss tangent. Dielectric constant of infected bile and gastric juice varies from patient to patient. Detection and extraction of bile stone with possible method of treatment is also discussed.
Mathew, K T; Biju Kumar, S; Anil, Lonappan; Joe, Jacob; Jacob, Samuel; Thommachan, Xavier; Thomas, Kurian(Elsevier Science, October , 2002)
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Abstract:
Ionic polymers (ionomers) with interesting characteristics are emerging as important commercial polymers. Ionomers have
the unique ability to behave as cross-linked materials at ambient temperatures and to melt and flow at elevated temperatures like
thermoplastics. The complex permittivity and conductivity of a class of ionomers at microwave frequencies are determined
using the cavity perturbation technique and the results are presented.
Bindu, G; Anil, Lonappan; Vinu, Thomas; Aanandan,C K; Mathew, K T(Progress In Electromagnetics Research, 2006)
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Abstract:
Permittivity and conductivity studies of corn syrup in
various concentrations are performed using coaxial cavity perturbation
technique over a frequency range of 250 MHz–3000 MHz. The results
are utilized to estimate relaxation time and dipole moments of the
samples. The stability of the material over the variations of time is
studied. The measured specific absorption rate of the material complies
with the microwave power absorption rate of biological tissues. This
suggests the feasibility of using corn syrup as a suitable, cost effective
coupling medium for microwave breast imaging. The material can also
be used as an efficient breast phantom in microwave breast imaging
studies.
Bindu, G; Anil, Lonappan; Vinu, Thomas; Aanandan,C K; Mathew, K T(Springer, November 1, 2006)
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Abstract:
Phantoms that exhibit complex dielectric
properties similar to low water content biological tissues
over the electromagnetic spectrum of 2–3 GHz
have been synthesized from carbon black powder,
graphite powder and polyvinyl-acetate-based adhesive.
The materials overcome various problems that are
inherent in conventional phantoms such as decomposition
and deterioration due to the invasion of bacteria
or mold. The absorption coefficients of the materials
for various compositions of carbon black and graphite
powder are studied. A combination of 50% polyvinylacetate-
based adhesive, 20% carbon black powder and
30% graphite powder exhibits high absorption coefficient,
which suggests another application of the material
as good microwave absorber for interior lining of
tomographic chamber in microwave imaging. Cavity
perturbation technique is adopted to study the dielectric
properties of the material.
Tessamma, Thomas; Tina, George P(BioMed Central Ltd, January 18, 2010)
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Abstract:
This paper compares the most common digital signal processing methods of exon
prediction in eukaryotes, and also proposes a technique for noise suppression in exon prediction.
The specimen used here which has relevance in medical research, has been taken from the public
genomic database - GenBank.Here exon prediction has been done using the digital signal processing methods viz.
binary method, EIIP (electron-ion interaction psuedopotential) method and filter methods. Under
filter method two filter designs, and two approaches using these two designs have been tried. The
discrete wavelet transform has been used for de-noising of the exon plots.Results of exon prediction based on the methods mentioned above, which give values
closest to the ones found in the NCBI database are given here. The exon plot de-noised using
discrete wavelet transform is also given.Alterations to the proven methods as done by the authors, improves performance
of exon prediction algorithms. Also it has been proven that the discrete wavelet transform is an
effective tool for de-noising which can be used with exon prediction algorithms