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
HIV/AIDS is one of the most destructive epidemics in
ever recorded history claims an estimated 2.4 –3.3 million lives every
year. Even though there is no treatment for this pandemic Elisa and
Western Blot tests are the only tests currently available for detecting
HIV/AIDS. This article proposes a new method of detecting HIV/AIDS
based on the measurement of the dielectric properties of blood at the
microwave frequencies. The measurements were made at the S-band of
microwave frequency using rectangular cavity perturbation technique
with the samples of blood from healthy donors as well as from HIV/AIDS patients. An appreciable change is observed in the dielectric properties
of patient samples than with the normal healthy samples and these
measurements were in good agreement with clinical results. This measurement
is an alternative in vitro method of diagnosing HIV/AIDS using microwaves.
In this paper, a multiband antenna using a novel
fractal design is presented. The antenna structure is formed
by inscribing a hexagonal slot within a circle. This base
structure is then scaled and arranged within the hexagon
along its sides without touching the outer structure. The
proposed CPW fed, low profile antenna offers good
performance in the 1.65 – 2.59 GHz, 4.16 – 4.52 GHz and
5.54 – 6.42 GHz bands and is suitable for GSM 1800/1900,
Bluetooth, IMT advanced systems and upper WLAN
applications. The antenna has been fabricated on a substrate
of height 1.6 mm and εr = 4.4 and simulation and
experimental results are found to be in good agreement
Gijo,Augustin; Shynu, S V; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave and Optical Technology Letters, April 20, 2005)
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Abstract:
An innovative phaseshifterless, wideband, micrustrip
leaky-wave antenna with an electronically steerable dual-pencil-beam
pattern in the H-plane is presented. The log-periodic geometry of the
leaky slots of the antenna results in a wide bandwidth of 25.19%. The
Jan beam can he steered up to 14° over the wide resonating band of the
anteww. The beam is also steerable at a fixed frequency. by reactivelty
loading the slots and a maximum steering angle of about 14° is ohserved.
for different capacitor values with an improved bandwidth of
33 _i%. This concept is studied using passive components but it can be extended to varactors
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.
A dual port dual polarized octagonal microstrip patch antenna suitable for dual band applications is discussed
theoretically and experimentally. The antenna exhibits good impedance bandwidth, gain and broad radiation patterns.
Parameters predicted by the Conformal Finite Difference Time Domain algorithm show good agreement with the
simulated results and experimental observations
The paper proposes an octagon shaped Microstrip Patch Antenna suitable for
dual band applications. The striking features of this compact, planar antenna are
sufficient isolation between the two operating bands and an area reduction of -
29% in comparison to a conventional circular patch antenna operating in the
same band
Description:
Antennas and Propagation Society International Symposium, 2002. IEEE
Tessamma, Thomas; Dinesh Kumar, V P(Pleiades Publishing, Ltd, 2008)
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Abstract:
This paper reports a novel region-based shape descriptor based on orthogonal Legendre moments.
The preprocessing steps for invariance improvement of the proposed Improved Legendre Moment Descriptor
(ILMD) are discussed. The performance of the ILMD is compared to the MPEG-7 approved region shape
descriptor, angular radial transformation descriptor (ARTD), and the widely used Zernike moment descriptor
(ZMD). Set B of the MPEG-7 CE-1 contour database and all the datasets of the MPEG-7 CE-2 region database
were used for experimental validation. The average normalized modified retrieval rate (ANMRR) and precision-
recall pair were employed for benchmarking the performance of the candidate descriptors. The ILMD has
lower ANMRR values than ARTD for most of the datasets, and ARTD has a lower value compared to ZMD.
This indicates that overall performance of the ILMD is better than that of ARTD and ZMD. This result is confirmed
by the precision-recall test where ILMD was found to have better precision rates for most of the datasets
tested. Besides retrieval accuracy, ILMD is more compact than ARTD and ZMD. The descriptor proposed is
useful as a generic shape descriptor for content-based image retrieval (CBIR) applications
Description:
Pattern Recognition and Image Analysis, 2008, Vol. 18, No. 1, pp. 23–29
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; Anila, P V; Indhu, K K; Nijas, C M; Sujith, R; Mohanan, P(Wiley Subscription Services, Inc., A Wiley Company, March 1, 2014)
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Abstract:
An electrically small, broadband-modified, truncated
ground metamaterial EZ antenna is presented. This, a modified EZ
antenna system, achieves a larger bandwidth of the order of 650 MHz
by adjusting the metamaterial-inspired meandered ground element fed
by a top loaded monopole. The design is devoid of the large ground
planes and the external parasitic elements used in conventional
designs for achieving proper impedance matching characteristics. The
antenna requires a small foot print of kg/5 3 kg/10, where kg is the
guided wavelength corresponding to the lowest frequency of operation,
when printed on a substrate of dielectric constant 4.4 and thickness
1.6 mm. The antenna offers a 2:1 VSWR bandwidth from 750
MHz to 1.4 GHz, which covers CDMA, GSM, and ISM bands
Description:
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 3, March 2014
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
Mridula, S; Sarah, Jacob; Aanandan,C K; Shameena, V A; Mohanan, P; Vasudevan, K(Wiley Periodicals, December 2, 2011)
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Abstract:
A compact coplanar waveguide-fed (CPW) monopole antenna for ultra-wideband
wireless communication is presented. The proposed antenna comprises of a CPW-fed
beveled rectangular patch with a modified slotted ground. The overall size of the antenna is
30 mm 27 mm 1.6 mm. The lower edge of the band is attained by properly decoupling
the resonant frequencies due to the extended ground plane and the beveled rectangular
patch of the antenna. The upper edge of the radiating band is enhanced by beveling the
ground plane corners near the feed point. Experimental results show that the designed
antenna operates in the 2.7–12 GHz band, for S11 10 dB with a gain of 2.7–5 dBi. Both
the frequency domain and time domain characteristics of the antenna are investigated using
antenna transfer function. It is observed that the antenna exhibits identical radiation patterns
and reasonable transient characteristics over the entire operating band
Description:
International Journal of RF and Microwave Computer‐Aided Engineering,VOL 22,issue 5,pp 594-602
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)