The recent boom in wireless communication industry, especially in the area of cellular
telephony and wireless data communication, has led to the increased demand for multi
band antennas. In such applications the issues to be addressed are, wide bandwidth and
gain, while striving for miniature geometry.
A dual frequency configuration useful in GSM1800 and Blue tooth, is one that operates
with similar properties, both in terms of reflection and radiation characteristics, in the two
bands of interest. Dual frequency operations can be realized by exciting the Microstrip
Patch Antenna (MPA) using a single feed [1] or dual feed [2].
In this paper, Conformal FDTD[3] method with Perfect Magnetic Conductor (PMC)
applied along the plane of symmetry [4] is used to study the characteristics of an
Octagonal MPA. The theoretical results are compared against the experimental and
IE3D™ simulated results
Description:
Antennas and Propagation Society International Symposium, 2007 IEEE,PP 5259-5262
Pravinkumar,P A; Mohanan, P; K G Nair(Indian Journal of Radio & Space Physics, December , 1981)
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Abstract:
A technique for improving the coupling between a feed horn and reflector by using corrugated metallic flanges is presented.
Experimental data for flanges of varying parameters are given and theoretical explanation is supplemented
This paper presents the design and
development of a compact CPW fed quad band
antenna. This low profile antenna has a dimension
of 32mmx31mm when printed on a substrate of
dielectric constant 4.4 and height 1.6mm. The
antenna covers GSM 900, DCS 1800,
IEEE802.11.a, IEEE802.11.b and HiperLAN2
bands. The antenna exhibits good radiation
characteristics with moderate gain
Shynu, S V; Augustin, G; Aanandan,C K; Mohanan, P; Vasudevan, K(IET, March 16, 2006)
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Abstract:
A new electronically reconfigurable dual frequency microstrip patch antenna with highly simplified varactor tuning circuitry is presented. The proposed design allows relatively independent selection of the two operating frequencies. Tuning ranges of 7.1 and 4.1% are realised for the two resonant frequencies without the use of any matching circuits.
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.