Advanced Electromagnetics (E-Journal)
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High Sensitive FBG Based Muscular Strain Sensor
No full textAssessment of biomechanical behavior of human musculoskeletal structure is essential to recognize bone diseases and to design proper medical devices. The skeleton system basically adapts to mechanical loadings. Thus, monitoring the bone deformation under load is of great importance to attain better analysis and interpretation. In recent years, Fiber Bragg Grating sensing devices have been developed and used to monitor strain and temperature of skeleton system. In this work a Fiber Bragg Grating sensor is designed holding a 1.54 pmµε-1 axial strain sensitivity which is almost 30% higher than the one achieved so far. The improvement in sensitivity is achieved by adjusting single-mode optical fiber parameters of the structure
Fast Wideband Solutions Obtained Using Model Based Parameter Estimation with Method of Moments
No full textIntegration of the Model Based Parameter Estimation (MBPE) technique into Method of Moments (MOM) provides fast solutions over a wide frequency band to solve radiation and scattering problems. The MBPE technique uses the Padé rational function to approximate solutions over a wide frequency band from a solution at a fixed frequency. In this paper, the MBPE technique with MOM is applied to a thin-wire antenna. The solutions obtained by repeated simulations of MOM agree very well with the solutions obtained by MBPE technique in a single simulation. Therefore, MBPE technique according to MOM provides a remarkable saving in the computation time. Computed results show that solutions at a wider frequency band of interest are achieved in a single simulation
Power Spectra of Ionospheric Scintillations
No full textSecond order statistical moments of the phase fluctuationsare obtained taking into account the boundary condition,diffraction effects and polarization coefficients of theordinary and extraordinary waves. The variance and thecorrelation function are calculated for arbitrary 3D spectralfunction of electron density fluctuations containing bothanisotropic Gaussian and power-law spectra; anisotropycoefficient and the orientation angle of elongated plasmairregularities. The phase scintillation index and thescintillation level are analyzed numerically. Maximum ofthe scintillation index for small-scale irregularities is in theinterval 0.2-0.3 corresponding to the moderate scintillationintensity, within the weak-scatter regime. Splashes arerevealed for different anisotropy factor of elongated largescaleirregularities varying orientation angle with respect tothe lines of force of geomagnetic field. Scintillation index iscalculated for small-scale irregularities using the “frozenin”assumption and taking into account movement of rigidirregularities. Log-log plots of the power spectrum of theintensity fluctuations have the same minimums satisfyingthe “standard relationship” of scattered ordinary andextraordinary waves. It was shown that the normalizedscintillation level growth in both non-fully-developeddiffraction pattern and in transition zone increasinganisotropy factor. Rising orientation angle scintillation leveldecreases and splashes arises in fully developedscintillation region
Modification of the transmission spectrum of the ”semiconductor-dielectric” photonic crystal in an external magnetic field
No full textIn this paper, some features of electromagnetic transmission of the waves of ”semiconductor dielectric” periodic Bragg structure with a finite number of periods have been investigated. In the absence of absorption, for a structure with p-type semiconductor layers, we have analyzed the dependences on the external magnetic field of photon spectrum and transmission coefficient spectrum. It has been shown that with an increasing magnetic field, there is a significant narrowing of bandwidth and broadening of band gaps, as well as formation of new band gaps in the resonance region. The boundaries of all forbidden and allowed bands are shifted to higher frequencies with the increase of the angle of radiation incidence
Fractal Shaped Antenna based tri-band Energy Harvester
No full textEnergy can be conserved by reusing what has already been spent. Such type of energy is readily available in the electromagnetic form (ambient RF energy). Signals broadcasted from AM, FM, cellular base stations and millions of other wireless devices can be converted to DC power. However, the main roadblock in this field of research is the level of power that ambient radiation carries. High efficiency antennas and rectifier circuits are required to harvest a fair amount of energy that can be used by low power devices. This paper presents the design of a novel multiband fractal antenna and a rectifier circuit that can be used to harvest ambient RF energy
A simple numerical experiment of Green's function expansion in the Fast Multipole Method
No full textIn this paper the theoretical foundation of the fast multipole method applied to problems involving electromagnetic scattering is briefly presented, the truncation of the Green’s function expansion is revisited, and the well established truncation criteria, in terms of the relative accuracy of the solutions of the electric field integral equation, is revised from a numerical experiment. Finally, from this numerical procedure an interesting result for the number L of poles is reported
Ring Slotted Circularly Polarized U-Shaped Printed Monopole Antenna for Various Wireless Applications
No full textIn this communication, the design and performance of strip line feed U-shaped printed monopole antenna for Bluetooth/WI-Max/WLAN communications systems is reported. Proposed monopole antenna has an eight shaped slot on the patch and an eight shaped ring structure in the ground plane with metallic reflector just beneath the radiating element. The CST Microwave Studio 2014 is used for the simulation analysis of antennas while measurements are performed by applying Vector Network Analyzer. This radiating structure provides triple broad impedance bandwidths i.e. 265MHz (in 2.280 GHz to 2.545 GHz frequency range), 116 MHz (in 2.660 GHz to 2.776 GHz frequency range) and 2.12 GHz (in 3.83 GHz to 5.956 GHz frequency range), wider 3dB axial ratio bandwidth 1.33 GHz (in 4.69GHz to 6.02GHz range), flat gain (with maximum gain close to 5.56 (dBi) and good radiation patterns in the desired frequency range. This antenna may be a useful structure for 2.45GHz Bluetooth communication band as well as in WLAN and Wi-Max communications bands
Compact Tri-Band Notched Characteristics UWB Antenna for WiMAX, WLAN and X-Band Applications
No full textCompact microstrip-fed printed monopole antenna with triple band-notched characteristics is suggested for ultra-wideband (UWB) applications. The antenna is constructed of a conventional rectangular microstrip patch antenna with partial ground plane and T-shaped strip employed in the ground plane as well as an inverted Ω- and L-shaped slots incorporated within the radiated element. The notched functions are created by the inverted Ω- and L-shaped slots, which are realized for WiMAX (from 2.69 to 4.5 GHz) and WLAN (from 5.49 to 6.37 GHz). The T-shaped parasitic strip generates the third notch for the X-band uplink satellite communication (from 8.15 to 9.61 GHz). The measured operating -10 dB bandwidth of the proposed antenna extends from 2.39 to more than 18 GHz except at the notched bands. The prototype antenna has a total area of 20×20×1.6 mm3. Electromagnetic (EM) simulations are carried out using 3D full-wave FEM-based simulator. EM simulation results are in good agreement with measurement results. The radiation pattern of the proposed antenna is nearly Omni-directional over the whole targeted band
HYDROFLASH: A 2-D Nuclear EMP Code Founded on Finite Volume Techniques
No full textThe basic mechanisms that govern the generation of an electromagnetic pulse (EMP) following a nuclear detonation in the atmosphere, including heights of burst (HOB) relevant to surface bursts (0 km), near surface bursts (0-2 km), air bursts (2-20 km) and high-altitude bursts (> 20 km), are reviewed. Previous computational codes developed to treat the source region and predict the EMP are discussed. A new 2-D hydrodynamic code (HYDROFLASH) that solves the fluid equations for electron and ion transport in the atmosphere and the coupled Maxwell equations using algorithms extracted from the Conservation Law (CLAW) package for solving multi-dimensional hyperbolic equations with finite volume techniques has been formulated. Simulations include the ground, atmospheric gradient, and an azimuthal applied magnetic field as a first approximation to the geomagnetic field. HYDROFLASH takes advantage of multiprocessor systems by using domain decomposition together with the Message Passing Interface (MPI) protocol for parallel processing. A detailed description of the model is presented along with computational results for a generic 10 kiloton (kT) burst detonated at 0 and 10 km altitude
CSRR Loaded 2x1 Triangular MIMO Antenna for LTE Band Operation
No full textA 2´1 (two-element) multiple-input multiple-output (MIMO) patch antenna system is designed and fabricated for (2.43 – 2.57) GHz LTE band 7 operation. It uses comple-mentary split -ring resonator (CSRR) loading on its ground plane for antenna miniaturization. This reduces the single-element antenna size by 76%. The total board size of the proposed MIMO antenna system, including the GND plane is 50´50´0.8mm3, while the single-patch antenna element has a size of 18.5 ´16mm2. The antenna is fabricated and tested. Measured results are in good agreement with simulations. A minimum measured isolation of 10 dB is obtained given the close interelement spacing of 0.17λ