Advanced Electromagnetics (E-Journal)
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Tunable Elliptical Split Ring Resonator Using Single Varactor Diode
No full textIn this paper, the effect of changing the structure of split ring resonator SRR from circular to elliptical shape is presented and tested. The theoretical analysis of circular SRR (CSRR) is tested and its results are compared with the simulated ones. Comparison between both configurations is introduced. The new elliptical SRR (ESRR) can be adapted to operate in multi range of frequencies. The effect of gap position in ESRR resonant is also examined. When both gaps are moved but still aligned, the resonant frequency still the same. But when single gap is moved only the resonant frequency the resonant frequency in changed to reach its maximum value when both gaps are in the same position. Frequency tunability can be offered by loading a single variable capacitor between ESRR metallic rings. The resonant frequency of the ESRR can be controlled by varying the capacitance of the varactor diode. Finite element method FEM is used to simulate the proposed structures using HFSS
Analytical results for rotating and linear magnetic brakes
No full textA theory of magnetic damper (eddy-current brake) which can be applied to axial-flux rotating and linear systems moving under the influence of an arbitrary arrangement of magnetic poles is derived from basic electromagnetic principles. Analytical expressions for the braking forces and torques are obtained in the low-velocity limit of the moving nonmagnetic conductor
A Novel LS/LMMSE Based PSO Approach for 3D-Channel Estimation in Rayleigh Fading
No full textA high transmission rate can be obtained using Multi Input Multi Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) model. The most commonly used 3D-pilot aided channel estimation (PACE) techniques are Least Square (LS) and Least Minimum Mean Square (LMMSE) error. Both of the methods suffer from high mean square error and computational complexity. The LS is quite simple and LMMSE being superior in performance to LS providing low Bit Error Rate (BER) at high Signal to Noise ratio (SNR). Artificial Intelligence when combined with these two methods produces remarkable results by reducing the error between transmission and reception of data signal. The essence of LS and LMMSE is used priory to estimate the channel parameters. The bit error so obtained is compared and the least bit error value is fine-tuned using particle swarm optimization (PSO) to obtained better channel parameters and improved BER. The channel parameter corresponding to the low value of bit error rate obtained from LS/LMMSE is also used for particle initialization. Thus, the particles advance from the obtained channel parameters and are processed to find a better solution against the lowest bit error value obtained by LS/LMMSE. If the particles fail to do so, then the bit error value obtained by LS/LMMSE is finally considered. It has emerged from the simulated results that the performance of the proposed system is better than the LS/LMMSE estimations. The performance of OFDM systems using proposed technique can be observed from the imitation and relative results
SAR Evaluation of Metallic Loop-like Accessory Effect of Broadband Wearable Planar Monopole Textile Antenna
No full textThis paper presents the investigation influence of the common metallic loop like accessory on Specific Absorption Rate (SAR) averaged over 10g and 1 g tissue.The simulations were made by means CST Microwave Studio software at frequencies 2.45GHz and 2.6GHz. Numerical analysis conducted using broadband textile monopole antenna (TM) with variations of orientation and distance showed that the SAR value increased when the antenna horizontally polarized.This is up to 80% more than vertically polarized TM placed closest item to 2mm
A A Compact Bandwidth Enhanced Antenna Loaded with SRR For WLAN/WiMAX/Satellite Applications
No full textA compact bandwidth enhanced antenna using metamaterial single Rectangular Split Ring Resonator (RSRR) for WLAN/WiMAX/Satellite applications is presented. As the wireless modules continue to shrink, there exists a drastic demand for a compact antenna. In addition to this, the effective integration of an antenna in wireless devices acts as stand-alone implement to mitigate the effects of noise fading. The presented antenna consists of three metamaterial single RSRR and a coaxial feed. Compactness in the design is achieved with the help of coaxial feeding technique. The etching of Upper metamaterial single RSRR creates a resonance at 6 GHz (WLAN) band, with S11 < -10 dB bandwidth ranging from 5.46 – 6.7 GHz (1240 MHz). Bandwidth enhancement in the proposed design at 6 GHz, is accomplished by the two metamaterial single RSRR placed at the left and ride side of the radiating patch, just below the upper RSRR. Due to the placement of two lower RSRR the bandwidth of the proposed antenna gets enhanced from 1240 to 3120 MHz. The antenna has a size of only 20 x 18 x 2.54 mm3 . The antenna exhibits bi-directional and Omni-directional radiation characteristics in E and H-plane, respectively. Compact size, good impedance matching, stable radiation pattern and radiation efficiency greater than 95% are observed across the operational bandwidths of the designed antenna. The aforementioned advantages make the proposed antenna suitable for WLAN/WiMAX/Satellite applications
Radar Cross Section Reduction of Low Profile Fabry-Perot Resonator Antenna Using Checker Board Artificial Magnetic Conductor
No full textThis paper presents a novel low profile, high gain Fabry-Perot resonator antenna with reduced radar cross section (RCS). An artificial magnetic conductor which provides zero degree reflection phase at resonant frequency is used as the ground plane of the antenna to obtain the low profile behavior. A checker board structure consisting of two artificial magnetic conductor (AMC) surfaces with antiphase reflection property is used as the superstrate to reduce the RCS. The bottom surface of superstrate is perforated to act as partially reflective surface to enhance the directivity of antenna. The antenna has a 3 dB gain bandwidth from 9.32 GHz to 9.77 GHz with a peak gain of 12.95 dBi at 9.6 GHz. The cavity antenna also has reduced reflectivity with a maximum reduction of 14.5 dB at 9.63 GHz
Iterative Scattering by Two PEMC Elliptic Cylinders
No full textIterative procedure is implemented to derive rigorous solution to the problem of plane electromagnetic wave scattering by couple of perfect electromagnetic conducting (PEMC) elliptic cylinders due co and cross polarized scattered fields among cylinders. The translation addition theorem for Mathieu functions is enforced to compute the higher order scattered fields by single PEMC elliptic cylinder in terms of the other elliptic cylinder coordination system to impose the boundary conditions. The kth co and cross polarized scattered field coefficient expressions are extracted by iteration procedure without using matrix inversion
Review on Design of Frequency Selective Surfaces based on Substrate Integrated Waveguide Technology
No full textThe spectacular development of frequency selective surfaces (FSS) as a spatial filter, absorbers and reflectors made them feasible for the aerospace and defence applications. The intervention of substrate integrated waveguide (SIW) technology into FSS results in the improvement of unit cell structures and better performance by isolating them from inter-element interference. Such FSS structures with SIW cavities upholds the FSS properties and improves their selectivity and performance. Considering the diversity in applications of introducing SIW cavity technology into FSS, the aim of this paper is to furnish a study on the glimpse of EM design techniques to analyze this type of structures. Design topologies of narrowing bandwidth, dual resonance, the design of FSS with sharp sideband edges and frequency selective polarization rotating structures are presented. Further, a novel design for improving the bandwidth of reflective FSS is discussed based on SIW technology. Fabrication techniques pertaining to this type of structures are presented in brief
A Novel Dual Band Hexagonal Antenna for Bluetooth and Uwb Applications With Single Band Notched
No full textThis paper presents a regular hexagonal antenna for ultra wide bandwidth (UWB). Then this antenna is modified to obtain a dual band with single band notched.The Bluetooth band is integrated in ultrawideband (UWB) when the antenna is loaded by pair of inverte
Circularly Polarized Split Ring Resonator Loaded Slot Antenna
No full textA compact circularly polarized printed slot antenna operating at 2.45 GHz is reported. The antenna consists of a pair of rotated square split ring resonators (SRR) inside a rectangular slot etched on the ground plane of an FR-4 dielectric substrate. A microstrip open-loop feed is etched on the backside of the dielectric substrate to feed the slot and the split ring resonators. The overall size of the antenna is 60x42x1.6 mm3. The measured -10dB impedance bandwidth is 10.48% (2.38-2.64 GHz) and the measured 3dB axial ratio (AR) bandwidth covers the entire impedance bandwidth