Advanced Electromagnetics (E-Journal)
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299 research outputs found
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Highly Selective Dual-Mode Microstrip Bandpass Filters Using Triangular Patch Resonators
No full textIn this paper, highly selective dual-mode microstrip bandpass filters are proposed using horizontal and vertical slots formed on the surface of a triangular patch. Slots are responsible for splitting and coupling of dual degenerate modes and also facilitate in controlling their resonant frequencies by varying the dimensions of the slots. Horizontal and vertical slots reroute the direction of the flow of current on the surface of the patch, which results in switching of transmission zeros. Two 2-pole and one 4-pole dual-mode filters are designed, simulated and fabricated. Two pole filters have transmission zeros on side of the passband and four pole filter have transmission zeros on both sides of the passband. The designed filters exhibit a fractional bandwidth of less than 7 % and there is a good agreement between simulated and measured results
Direction of Arrival Estimation in the presence of Scatterer in noisy environment
No full textWe present an algorithm to estimate direction of arrival (DOA) of an incoming wave received at an array antenna in the scenario where the incoming wave is contaminated by the additive white Gaussian noise and scattered by arbitrary shaped 3D scatterer(s). We present different simulation examples to show the validity of the proposed method. It is observed that the proposed algorithm is capable of closely estimating the DOA of an incoming wave irrespective of the shape of the scatterer provided the decision is made over multiple iterations. Moreover, presence of noise affects the estimate especially in the case of low signal-to-noise ratio (SNR) that gives a relatively large estimation error. However, for larger SNR the DOA estimation is primarily dependent on the scatterer only
Performance Improvement of Ultra Wideband Multiple Access Modulation System using a new Optimal Pulse Shape
No full textUltra-wideband (UWB) uses very low energy levels to transfer data at very high data rate and bandwidth. An optimal and correct choice of transmission pulse shape is an important criterion in this technology. In this paper, we will present an approach for the generation of an optimal pulse shape with the optimal generation of pulse shape values that can provide effective results when transmitted using multiple access modulation technique over a multipath channel and received by a RAKE type receiver. The bit error analysis of constructed model is also given using Ideal Rake, selective RAKE, and partial RAKE receiver configurations
Strain and Curvature Stability Enhanced SMF Introduction
No full textIn this paper, the strain insensitive single mode optical fiber with low nonlinear effects and ultra low bending loss (BL), appropriate for small curvature radius installation, is presented. The suggested design method is based on the reverse engineering which evaluates the refractive index profile considering proper mode field diameter (MFD) value. Then, so as to attain the desired bending loss and strain response for the optical fiber, the optimization tool of the evolutionary genetic algorithm (GA) is employed to determine the optical and geometrical parameters of the structure. In the first designed fiber, the calculations for BL, MFD, effective area (Aeff), and effective refractive index (neff) sensitivity to strain in the well-known wavelength of 1.55 µm are 0.0018 dB per each turn of 5 mm curvature radius, 8.53 µm, 58 µm2, and 4.5 × 10-8 µɛ-1, respectively. Furthermore, the effect of placing raised outer cladding in the fiber structure is investigated which exhibits the MFD of 8.63 µm, 0.0093 dB BL for single turn of 5 mm radius, and 87 µm2 Aeff at 1.55 µm. In this case the strain sensitivity of 6.7 × 10-8 µɛ-1 is calculated for the neff. The mentioned effective area is magnificently large in the domain of bend insensitive fibers. In the meantime, the designed structures are insensitive to strain which is a crucial feature in applications with small curvature radius
A Broadband Ultrathin Nonlinear Switching Metamaterial
No full textIn this paper, an ultrathin planar nonlinear metamaterial slab is designed and simulated. Nonlinearity is provided through placing diodes in each metamaterial unit cell. The diodes are auto-biased and activated by an incident wave. The proposed structure represents a broadband switching property between two transmission and reflection states depending on the intensity of the incident wave. High permittivity values are presented creating a near zero effective impedance at low power states, around the second resonant mode of the structure unit cell; as the result, the incident wave is reflected. Increasing the incident power to the level which can activate the loaded diodes in the structure results in elimination of the resonance and consequently a drop in the permittivity values near the permeability one as well as a switch to the transmission state. A full wave as well as a nonlinear simulations are performed. An optimization method based on weed colonization is applied to the unit cell of the metamaterial slab to achieve the maximum switching bandwidth. The structure represents a 24% switching bandwidth of a 10 dB reduction in the reflection coefficient
Microwave Interferometry Based On Open-ended Coaxial Technique for High Sensitivity Liquid Sensing
No full textThis paper describes a modified open-ended coaxial technique for microwave dielectric characterization in liquid media. A calibration model is developed to relate the measured transmission coefficient to the local properties of the sample under test. As a demonstration, the permittivity of different sodium chloride solutions is experimentally determined. Accuracies of 0.17% and 0.19% are obtained respectively for the real and imaginary parts of dielectric permittivity at 5.9 GHz
Microwave microscopy applied to EMC problem: Visualisation of electromagnetic field in the vicinity of electronic circuit and effect of nanomaterial coating
No full textThis proposal is devoted to a collaborative approach dealing with microwave microscopy experiments. The application is dedicated to an electromagnetic field cartography above circuits and the influence of nanometric material layer deposition on the circuits. The first application is associated to a microstrip ring resonator. The results match with the simulated fields. The second application is focused on the effects of a dielectric layer deposited on the circuit and its impact in terms of electromagnetic propagation
Effect of the Base-band Measurement Setup Errors on DPD Performance and Elimination Procedure
No full textIn this study, the effect of base-band measurement setup errors on DPD performance was investigated and a calibration procedure is developed to eliminate the measurement errors. A base-band measurement setup is prepared at laboratory with instruments and then the data which is measured and the deteriorating effect of errors on Digital Predistortion (DPD) linearization performance are investigated. In order to eliminate deteriorating effect of this error a three steps calibration procedure is developed. Before and after calibration application DPD performance is measured. It is showed both in simulation and experimentally that the calibration procedure improved the DPD system linearization performance from 10 dB to 26dB and 13dB to 20dB, respectively
Grating-based Dipole Antenna Configuration for High Gain Directional Radiation characteristics
No full textThe experimental and simulation studies of the radiation performance enhancement of a dipole antenna using metal strip grating are presented in this paper. The subwavelength imaging configuration of the metal strip grating is utilized for enhancing the radiation performance of a dipole antenna working in the S-band. The resultant design shows a gain of 9 dBi and front to back ratio of the design is found to be -23 dB at resonance. The coupling between electric and magnetic resonances provides the necessary impedance matching performance when the antenna is brought in the vicinity of the grating
Beam Diversity Analysis of Compact Microstrip Antenna with Suspended Superstrate: An Experimental Study
No full textA multi-functional microstrip compact antenna capable of steering the main beam to eight different directions in the elevation plane is conferred in this study. The compact antenna consists of a driven patch of to bring in the resonance to , for achieving enormous application in european radar service under Wi-MAX band. The conductive layer on the superstrate deflect the beam with an angle corresponding to the position of superstrate on parasitic layer, without considering complex phase shifters and associated circuits. Proper alignment of superstrate results maximum scanning angle ofwithof deflection angle. The directivity of the antenna is enhanced by manipulating the parameters of the superstrate. The gain of the antenna was improved up to and the efficiency is improved up to using engineered superstrate. The full-wave simulation as well as analytical study was done using the IE3D EM simulator