Abstract: A compact Ultra Wide Band (UWB) antenna with coplanar
waveguide feed has been designed and results are verified in
this paper. The antenna has been designed on FR4 substrate with
dielectric constant (εr) of 4.4 and dimensions of 32mm x 26mm x
0.8mm. The presented antenna shows return loss characteristics in the
band of 3.1 to 10.6 GHz as prescribed by FCC, USA. Parametric
studies have been done and results thus obtained have been
presented. Simulated results have been verified on Rohde & Swartz
VNA. The measured results are in good agreement with simulated
results which make the presented antenna suitable to be used for
wearable applications. Performance analysis of antenna has also been
shown in the presence of three layered Human Arm model. Results
obtained in presence of Human Arm model has been compared with
that in free space.
Abstract: Optical biosensors have become a powerful detection
and analysis tool for wide-ranging applications in biomedical research,
pharmaceuticals and environmental monitoring. This study carried out
the computational fluid dynamics (CFD)-based simulations to explore
the dispersion phenomenon in the micro channel of an optical
biosensor. The predicted time sequences of concentration contours
were utilized to better understand the dispersion development occurred
in different geometric shapes of micro channels. The simulation results
showed the surface concentrations at the sensing probe (with the best
performance of a grating coupler) in respect of time to appraise the
dispersion effect and therefore identify the design configurations
resulting in minimum dispersion.
Abstract: This paper presents a study of SIW circuits (Substrate
Integrated Waveguide) with a rigorous and fast original approach
based on Iterative process (WCIP). The theoretical suggested study is
validated by the simulation of two different examples of SIW
circuits. The obtained results are in good agreement with those of
measurement and with software HFSS.
Abstract: The dielectric properties and ionic conductivity of
novel "ceramic state" polymer electrolytes for high capacity lithium
battery are characterized by Radio frequency and Microwave
methods in two broad frequency ranges from 50 Hz to 20 KHz and 4
GHz to 40 GHz. This innovative solid polymer electrolyte which is
highly ionic conductive (10-3 S/cm at room temperature) from -40oC
to +150oC can be used in any battery application. Such polymer
exhibits properties more like a ceramic rather than polymer. The
various applied measurement methods produced accurate dielectric
results for comprehensive analysis of electrochemical properties and
ion transportation mechanism of this newly invented polymer
electrolyte. Two techniques and instruments employing air gap
measurement by Capacitance Bridge and in-waveguide measurement
by vector network analyzer are applied to measure the complex
dielectric spectra. The complex dielectric spectra are used to
determine the complex alternating current electrical conductivity and
thus the ionic conductivity.
Abstract: This paper presents a novel fractal antenna structure
proposed for UWB (Ultra – Wideband) applications. The frequency
band 3.1-10.6GHz released by FCC (Federal Communication
Commission) as the commercial operation of UWB has been chosen
as frequency range for this antenna based on coplanar waveguide
(CPW) feed and circular shapes fulfilled according to fractal
geometry. The proposed antenna is validated and designed by using
an FR4 substrate with overall area of 34x43 mm2. The simulated
results performed by CST-Microwave Studio and compared by ADS
(Advanced Design System) show good matching input impedance
with return loss less than -10dB between 2.9 GHz and 11 GHz.
Abstract: This paper presents the electromagnetic interference
(EMI) shielding effectiveness of rice husk and carbon nanotubes
(RHCNTs) composites in the X-band region (8.2-12.4 GHz). The
difference weight ratio of carbon nanotubes (CNTs) were mix with
the rice husk. The rectangular waveguide technique was used to
measure the complex permittivity of the RHCNTs composites
materials. The complex permittivity is represented in terms of both
the real and imaginary parts of permittivity in X-band frequency. The
conductivity of RHCNTs shows increasing when the ratio of CNTs
mixture increases. The composites materials were simulated using
Computer Simulation Technology (CST) Microwave Studio
simulation software. The shielding effectiveness of RHCNTs and
pure rice husk was compared. The highest EMI SE of 30 dB is
obtained for RHCNTs composites of 10 wt % CNTs with 10mm
thickness.
Abstract: A wireless sensor network (WSN) is a collection of
sensor nodes organized into a cooperative network. These nodes
communicate through a wireless antenna. Reduction in physical size
and multiband operation is an important requirement of WSN
antenna. Fractal antenna is used for miniaturization and multiband
operation. The self-similar or self-affine and space filling property of
fractal geometry increases the effective electrical length of the
antenna, reduces the size and make them frequency independent. This
paper elaborates on Dual band fractal antenna with Coplanar
Waveguide (CPW) feed for WSN. The proposed antenna is designed
on a FR4 substrate with the dimension of 27mm x 28.5mm x 1.6mm,
resonates at 2.4GHz and 5.2GHz with a return loss less than -10dB.
The design and simulation process is carried out using IE3D
simulation software. The simulated and measured results are found in
good agreement.
Abstract: This paper presents the design and analysis of Liquid
Crystal (LC) based tunable reflectarray antenna with different design
configurations within X-band frequency range. The effect of LC
volume used for unit cell element on frequency tunability and
reflection loss performance has been investigated. Moreover different
slot embedded patch element configurations have been proposed for
LC based tunable reflectarray antenna design with enhanced
performance. The detailed fabrication and measurement procedure
for different LC based unit cells has been presented. The waveguide
scattering parameter measured results demonstrated that by using the
circular slot embedded patch elements, the frequency tunability and
dynamic phase range can be increased from 180MHz to 200MHz and
120° to 124° respectively. Furthermore the circular slot embedded
patch element can be designed at 10GHz resonant frequency with a
patch volume of 2.71mm3 as compared to 3.47mm3 required for
rectangular patch without slot.
Abstract: We have studied a method to widen the spectrum
of optical pulses that pass through an InGaAsP waveguide for
application to broadband optical communication. In particular, we
have investigated the competitive effect between spectral broadening
arising from nonlinear refraction (optical Kerr effect) and shrinking
due to two photon absorption in the InGaAsP waveguide with
χ(3) nonlinearity. The shrunk spectrum recovers broadening by
the enhancement effect of the nonlinear refractive index near the
bandgap of InGaAsP with a bandgap wavelength of 1490 nm. The
broadened spectral width at around 1525 nm (196.7 THz) becomes
10.7 times wider than that at around 1560 nm (192.3 THz) without
the enhancement effect, where amplified optical pulses with a pulse
width of ∼ 2 ps and a peak power of 10 W propagate through a
1-cm-long InGaAsP waveguide with a cross-section of 4 (μm)2.
Abstract: This paper presents the design and analysis of Liquid
Crystal (LC) based tunable reflectarray antenna with different design
configurations within X-band frequency range. The effect of LC
volume used for unit cell element on frequency tunability and
reflection loss performance has been investigated. Moreover different
slot embedded patch element configurations have been proposed for
LC based tunable reflectarray antenna design with enhanced
performance. The detailed fabrication and measurement procedure
for different LC based unit cells has been presented. The waveguide
scattering parameter measured results demonstrated that by using the
circular slot embedded patch elements, the frequency tunability and
dynamic phase range can be increased from 180MHz to 200MHz and
120° to 124° respectively. Furthermore the circular slot embedded
patch element can be designed at 10GHz resonant frequency with a
patch volume of 2.71mm3 as compared to 3.47mm3 required for
rectangular patch without slot.
Abstract: Fluid rheology may have essential impact on sound propagation in a liquid-filled pipe, especially, in a low frequency range. Rheological parameters of liquid are temperature-sensitive, which ultimately results in a temperature dependence of the wave speed and attenuation in the waveguide. The study is devoted to modeling of this effect at sound propagation in an elastic pipe with polymeric liquid, described by generalized Maxwell model with non-zero high-frequency viscosity. It is assumed that relaxation spectrum is distributed according to the Spriggs law; temperature impact on the liquid rheology is described on the basis of the temperature-superposition principle and activation theory. The dispersion equation for the waveguide, considered as a thin-walled tube with polymeric solution, is obtained within a quasi-one-dimensional formulation. Results of the study illustrate the influence of temperature on sound propagation in the system.
Abstract: Narrow bandwidth and high loss performance limits the use of reflectarray antennas in some applications. This article reports on the feasibility of employing strategic reflectarray resonant elements to characterize the reflectivity performance of reflectarrays in X-band frequency range. Strategic reflectarray resonant elements incorporating variable substrate thicknesses ranging from 0.016λ to 0.052λ have been analyzed in terms of reflection loss and reflection phase performance. The effect of substrate thickness has been validated by using waveguide scattering parameter technique. It has been demonstrated that as the substrate thickness is increased from 0.508mm to 1.57mm the measured reflection loss of dipole element decreased from 5.66dB to 3.70dB with increment in 10% bandwidth of 39MHz to 64MHz. Similarly the measured reflection loss of triangular loop element is decreased from 20.25dB to 7.02dB with an increment in 10% bandwidth of 12MHz to 23MHz. The results also show a significant decrease in the slope of reflection phase curve as well. A Figure of Merit (FoM) has also been defined for the comparison of static phase range of resonant elements under consideration. Moreover, a novel numerical model based on analytical equations has been established incorporating the material properties of dielectric substrate and electrical properties of different reflectarray resonant elements to obtain the progressive phase distribution for each individual reflectarray resonant element.
Abstract: Silicon photonics is merging as a unified platform for driving photonic based telecommunications and for local photonic based interconnect but it suffers from large footprint as compared with the nanoelectronics. Plasmonics is an attractive alternative for nanophotonics. In this work, two CMOS compatible plasmonic waveguide platforms are compared. One is the horizontal metal-insulator-Si-insulator-metal nanoplasmonic waveguide and the other is metal-insulator-Si hybrid plasmonic waveguide. Various passive and active photonic devices have been experimentally demonstrated based on these two plasmonic waveguide platforms.
Abstract: Here we have considered non uniform microstrip
leaky-wave antenna implemented on a dielectric waveguide by a
sinusoidal profile of periodic metallic grating. The non distribution of
the attenuation constant α along propagation axis, optimize the
radiating characteristics and performances of such antennas. The
method developped here is based on an integral method where the
formalism of the admittance operator is combined to a BKW
approximation. First, the effect of the modeling in the modal analysis
of complex waves is studied in detail. Then, the BKW model is used
for the dispersion analysis of the antenna of interest. According to
antenna theory, a forced continuity of the leaky-wave magnitude at
discontinuities of the non uniform structure is established. To test the
validity of our dispersion analysis, computed radiation patterns are
presented and compared in the millimeter band.
Abstract: The state and stability of hemoglobin adsorbed on the
glass surface was investigated using slab optical waveguide (SOWG)
spectroscopy. The peak position of the absorption band of hemoglobin
adsorbed on the glass surface was same as that of the hemoglobin in
solution. This result suggests that no significant denaturation occurred
by adsorption. The adsorption of hemoglobin is relatively strong that
the hemoglobin molecules even remained adsorbed after rinsing the
cell with buffer solution. The peak shift caused by the reduction of
adsorbed hemoglobin was also observed.
Abstract: in this paper we modified a simple two-dimensional
photonic crystal waveguide by creating micro cavity resonators in order to increase the output light emission which can be applicable to photonic integrated circuits. The micro cavity resonators are constructed by removing two tubes close to the waveguide output. Coupling emitted light from waveguide with those micro cavities, results increasing intensity of waveguide output light. Inserting a tube
in last row of waveguide, we have improved directionality of output
light beam.
Abstract: In this paper, the application of the Mode Matching
(MM) method in the case of photonic crystal waveguide
discontinuities is presented. The structure under consideration is
divided into a number of cells, which supports a number of guided
and evanescent modes. These modes can be calculated numerically
by an alternative formulation of the plane wave expansion method
for each frequency. A matrix equation is then formed relating the
modal amplitudes at the beginning and at the end of the structure.
The theory is highly efficient and accurate and can be applied to
study the transmission sensitivity of photonic crystal devices due to
fabrication tolerances. The accuracy of the MM method is compared
to the Finite Difference Frequency Domain (FDFD) and the Adjoint
Variable Method (AVM) and good agreement is observed.
Abstract: In situ observation of absorption spectral change of
heptil viologen cation radical (HV+.) was performed by slab optical
waveguide (SOWG) spectroscopy utilizing indium-tin-oxide (ITO)
electrodes. Synchronizing with electrochemical techniques, we
observed the adsorption process of HV+.on the ITO electrode. In this
study, we carried out the ITO-SOWG observations using KBr aqueous
solution containing different concentration of HV to investigate the
concentration dependent spectral change. A few specific absorption
bands, which indicated HV+.existed as both monomer and dimer on
ITO electrode surface with a monolayer or a few layers deposition,
were observed in UV-visible region. The change in the peak position
of the absorption spectra from adsorption species of HV+. were
correlated with the concentration of HV as well as the electrode
potential.
Abstract: Traditional optical networks are gradually evolving towards intelligent optical networks due to the need for faster bandwidth provisioning, protection and restoration of the network that can be accomplished with devices like optical switch, add drop multiplexer and cross connects. Since dense wavelength multiplexing forms the physical layer for intelligent optical networking, the roll of high speed all optical switch is important. This paper analyzes such an ultra-high speed polymer electro-optic switch. The performances of the 2x2 optical waveguide switch with rectangular, triangular and trapezoidal grating profiles on various device parameters are analyzed. The simulation result shows that trapezoidal grating is the optimized structure which has the coupling length of 81μm and switching voltage of 11V for the operating wavelength of 1550nm. The switching time for this proposed switch is 0.47 picosecond. This makes the proposed switch to be an important element in the intelligent optical network.
Abstract: A pilot plant for continuous flow microwave-assisted
chemical reaction combined with microreactors was developed and
water heating tests were conducted for evaluation of the developed
plant. We developed a microwave apparatus having a single
microwave generator that can heat reaction solutions in four reaction
fields simultaneously in order to increase throughput. We also
designed a four-branch waveguide using electromagnetic simulation,
and found that the transmission efficiency at 99%. Finally, we
developed the pilot plant using the developed microwave apparatus
and conducted water heating tests. The temperatures in the respective
reaction fields were controlled within ±1.1 K at 353.2 K. Moreover,
the energy absorption rates by the water were about 90% in the
respective reaction fields, whereas the energy absorption rate was
about 40% when 100 cm3 of water was heated by a commercially
available multimode microwave chemical reactor.