Haddud,T A; Al-Mansoori,M H; Zamzuri,A K; Shaharudin,S; Abdullah,M K; Mahdi,M A(Microwave and Optical Technology Letters, April 20, 2005)
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Abstract:
In this paper, the generation of a multiwavelength laser
source from a Brillouin -Erbium fiber laser in the long wavelength band
(L-band) region is experimentally demonstrated. The proposed laser
system utilizes a Fabrv-Perot cavity formed by fiber-loop mirrors.
Twenty-four lines of Brillouin-Stokes with line spacings of 10 GHz are
obtained in the L-band region
Anupam,Chandran R; Thomaskutty,Mathew; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave and Optical Technology Letters, February 5, 2004)
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Abstract:
A novel technique for backscattering reduction for both TE
and TM polarisation, employing a metallo-dielectric structure based on
Sierpinski carpet fractal geometry, is reported. A reduction in backscattered
power of --30 dB is obtained for normal incidence in the X-band for the
structure using the third iterated stage of the fractal geometry
Lethakumary,B; Sreedevi, Menon K; Aanandan,C K; Vasudevan, K; Mohanan, P(Microwave and Optical Technology Letters, July 20, 2004)
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Abstract:
This paper presents the outcome of the experimental studies
performed on L-strip fed compact rectangular microstrip antenna.
The effect of the feed parameters upon the characteristics of the antenna
is studied in detail. The antenna offers an impedance bandwidth of
nearly 20% and is suitable for broadband applications
Sreedevi, Menon K; Lethakumary,B; Bijumon, P V; Sebastian,M T; Mohanan, P(Microwave and Optical Technology Letters, May 5, 2005)
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Abstract:
In this paper, the advantages of using L-shaped microviij)
feed to e.tcite a rectangular dielectric resonator cuuenna (DRA) by elemanagnetic
coupling are presented. This feeding technique enhances the
hardsvidth and gain of the antenna without affecting its size. The experimental
re srdts are validated using Fidelity software based on the finitedifference
tine-domain (FDTD) method
Mridula, S; Jacob,George; Mohanan, P(Microwave and Optical Technology Letters, December 20, 1999)
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Abstract:
A novel antenna configuration comprised of two circular
micro strip antennas (CMAs) resonating in the TMtt and TM2, modes,
producing radiation characteristics suitable for a mobile telephone handset,
is presented. The antennas operating at the same frequency are
placed back to back with a separation comparable to the thickness of a
typical handset. The radiation pattern consists of a region of reduced
radiation intensity, which minimizes the radiation hazards to the user
A novel antenna configuration comprised of two circular
microstrip antennas (CMAs) resonating in the TMtt and TM2, modes,
producing radiation characteristics suitable for a mobile telephone handset,
is presented. The antennas operating at the same frequency are
placed back to back with a separation comparable to the thickness of a
typical handset. The radiation pattern consists of a region of reduced
radiation intensity, which minimizes the radiation hazards to the user
Description:
Microwave and Optical Technology Letters,VOL 23,issue 6.pp 370-372
Jitha, B; Bybi, P C; Aanandan,C K; Mohanan, P(John Wiley & Sons, June , 2008)
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Abstract:
Design of a compact microstrip band reject filter is proposed. The device consists of an Open Loop Rectangular Resonator (OLRR) coupled to a microstrip line. The transmission line has a U-bend which enhances the coupling with the OLRR element and reduces the size of the filter. The filter can be made tunable by mounting variable capacitance to the system. Simulated and experimental results are presented.
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
A microwave dielectric ceramic resonator based on BaCe2Ti5O15 and Ba5Nb4O15 have been prepared by conventional solid state ceramic route. The dielectric resonators (DRs) have high dielectric constant 32 and 40 for BaCe2Ti5O15 and Ba5Nb4O15, respectively. The whispering gallery mode (WGM) technique was employed for the accurate determination of the dielectric properties in the microwave frequency range. The BaCe2Ti5O15 and Ba5Nb4O15 have quality factors (Q X F) of 30,600 and 53,000 respectively. The quality factor is found to depend on the azimuthal mode numbers. The temperature coefficient of resonant frequency (Tr) of BaCe2Ti5O15 and Ba5Nb4O15 have been measured accurately using different
resonant modes and are + 41 and + 78 ppm/K, respectively
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
microwave dielectric properties of ceramics based on Ba(Mgv3Ta(2-2x)t3W,t3Tixt3)O3 is investigated as a function of x. The
15 densification as well as dielectric properties deteriorate with increase in the substitution levels of (Ti 1,3W113)333 + at (Ta213)3.33+ site
16 in Ba(Mg113Ta213)03. The rt is approaching zero between x = 0.1 and 0.15 in Ba(Mg it3Ta(2-2,,.)t3W,it3Ti,Tt3)O3 where quality factor is
17 reasonably good (Qu x f = 80,000-90,000 GHz). The Ba(Mg1,3Ta(2_,013W,13Ti,,13)03 with x = 1.0 has e, = 15.4, rf= -25.1 ppm/
18 "C, Q„ x f = 35,400 GHz
The BaO-2CeO2-nTiO2 ceramics with n = 3, 4 and 5 have been prepared with CeO2 as starting material . The ceramics have been
characterized using scanning electron microscopy , X-ray diffraction , Raman and X-ray photoelectron spectroscopy techniques. The
microwave dielectric properties have been measured using standard dielectric resonator techniques . BaO-2CeO2-3TiO2 (123),
BaO-2CeO2-4TiO2 ( 124) and BaO-2CeO2-5TiO2 ( 125) ceramics showed dielectric constants of 38, 27 and 32, respectively . All the
ceramics showed fairly good unloaded Q - factors . 124 and 125 compounds exhibited low tf values, while 123 showed a high rf value
Isuhak, Naseembeevi Jawahar; Narayana Iyer, Santha; Mailadil, Thomas Sebastian(Materials Reserach Society, December , 2002)
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Abstract:
Single-phase polycrystalline ceramics in the MO-La2O3-Ti02 (M = Ca, Sr, Ba)
system, such as cation-deficient hexagonal perovskites CaLa4Ti4O15, SrLa4Ti4O15,
BaLa4Ti4O15, and Ca2La4Ti5O18 and the orthorhombic phases CaLa4Ti5O17 and
CaLa8Ti9O31, were prepared through the solid-state ceramic route. The phases
and structure of the ceramics were analyzed through x-ray diffraction and scanning
electron microscopy. The microwave dielectric properties of the ceramics were studied
using a network analyzer. The investigated ceramics show high Er in the range 42 to
54, high quality factors with Q x f in the range 16,222 to 50,215 GHz, and low Tf in
the range -25 to +6 ppm3/°C. These high dielectric constant materials with high Q x f
up to 50,215 GHz are suitable for applications where narrow bandwidth and extremely
low insertion loss is necessary, especially at frequencies around 1.9 GHz
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
Dielectric resonator ceramics with composition formula Ba[(D3+0.3 Bi0.2)Nb0.5]O3,where D3+=Y,Pr,Sm,Gd,Dy and Er,were prepared by the conventional ceramic preparation route