| Manuscript Title: | Influence of Nickel-Zinc Ratio on Power Loss of NixZn1-xFe2O4 using Microstrip Technique at Microwave Frequency |
| Manuscript Id: | JIMOT-2104-12-658 |
| Abstract: | The linear magnitude of reflection (|S11|) and transmission (|S21|) properties of the microstrip loaded with NixZn1-xFe2O4 were extensively studied. The microstrip measurements were conducted using a HP8720B vector network analyzer. It was found that NixZn1-xFe2O4 with higher values of x absorbed more microwave energy which in turn reduced the reflection and transmission coefficients. A good linear relationship was found between the absorption loss and fractional composition x at 3 GHz. The waves were totally absorbed by NixZn1-xFe2O4 at frequencies above 7 GHz for x ??0.5. |
| Authors: | F. Esa , Z. Abbas , Omar A. Fadhil , Abubakar Yakubu , M. A. Jusoh |
| Submitted On: | 23/12/2014 |
| Pages: | 71-78 |
| Action: | [Full Paper]
No. of Downloads: 76 |
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| Manuscript Title: | Design and Analysis of Performance Enhanced Microstrip Patch Antenna with EBG Substrate |
| Manuscript Id: | IJMOT-2014-10-633 |
| Abstract: | In recent years, to overcome limitations of patch antenna impedance bandwidth, use of Electromagnetic Bandgap substrates has found its importance. Unlike normal substrate, the EBG substrate is selective in supporting propagating surface waves. The basic idea used is that the resonating frequency of patch antenna lies outside the bandgap of EBG substrate for EBG shaped stacked patches and inside the band gap of EBG substrate to minimise surface waves. In this paper, Electromagnetic Band Gap (EBG) substrate is studied inside and outside its bandgap. A rectangular coaxial fed microstrip patch antenna with EBG shaped stacked patches is proposed. A bandwidth improvement of 37% over conventional patch antenna is obtained. As a result, the performance of the proposed antenna is better comparing the conventional existing microstrip patch antenna. Up to 6.73dB reduction in mutual coupling and 21.05dB improvement in return loss is also reported. |
| Authors: | Naveen Jaglan, Samir Dev Gupta |
| Submitted On: | 07/10/2014 |
| Pages: | 79-88 |
| Action: | [Full Paper]
No. of Downloads: 66 |
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| Manuscript Title: | TM Polarized Terahertz Waves In Left-Handed Cylindrical Materials |
| Manuscript Id: | IJMOT-2014-10-632 |
| Abstract: | The dispersion properties of transverse magnetic (TM ) waves propagating through a cylindrical wave-guide structure of a left handed material (LHM), have been investigated. We found that LHM wires of 0.5 mm could guide terahertz radiation. Based on the fact that the attenuation coefficient of the guided wave\r\ndecreases by decreasing the imaginary part of the dielectric constant and decreasing the absolute real part to a definite value. The wave amplification was achieved by increasing the permeability of LHM to some values. We demonstrated that the attenuation coefficient would be reduced to ratios of factor 3 10 and 4 10 in the whole range of 0.5-2 THz if a nonmagnetic monocrystalline bismuth(nonmagnetic LHM) and a copper wire were used respectively. Because the imaginary part of the dielectric constant of Bi can reach values on the order of 3 10??and the absolute value of the real part permittivity of copper in the spectral region of terahertz radiation is huge. Such a low loss and strong field confinement is extremely\r\nadvantageous for imaging and THz sensing. |
| Authors: | H. M. Mousa , M. M. Shabat |
| Submitted On: | 06/10/2014 |
| Pages: | 89-94 |
| Action: | [Full Paper]
No. of Downloads: 23 |
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| Manuscript Title: | Analysis and Design of a TEM-Split Ring Resonator for UHF-MRI |
| Manuscript Id: | IJMOT-2014-8-617 |
| Abstract: | In this paper we present the electromagnetic (EM) analysis of the TEM-split ring resonator (SRR) with a circular cross section, using both the finite element method (FEM) and the method of moments (MoM) in two dimensions. These numerical methods account for thickness effects in analyzing the primary parameters (L and C) as well as the characteristic impedance (Zc) for UHF-SRR resonators. The design of the UHF-MRI probe is based on the EM-parameters of the SRR, whereas the simulation of its frequency response of (S11) is done using transmission line method (TLM). The designed UHF-MRI probe with high Q operates at 340 MHz (proton imaging at 8 T) and has -116 dB minimum reflections. These results by our simulations using the transient solver of CST microwave studio software. The UHF-MRI probe using TEM-SRR is easy to construct,\r\ninexpensive, and simple to operate. Furthermore, the coil presented here may be constructed to work at different resonances frequencies. |
| Authors: | Fatima Seghiri , Nadia Benabdallah, Nasreddine Benahmed, Rachid Bouhmidi, Kamila Aliane |
| Submitted On: | 20/08/2014 |
| Pages: | 95-104 |
| Action: | [Full Paper]
No. of Downloads: 42 |
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| Manuscript Title: | Inclusion of Broadband Frequency Responses of Passive and Linear Networks into Circuit solver: Simple Approach using Vector Fitting |
| Manuscript Id: | IJMOT-2014-8-616 |
| Abstract: | This paper proposes an efficient and simple approach to embed broadband frequency domain responses of passive and linear networks into circuit solver using vector fitting method. Tabulated frequency domain data in the form of admittance matrix is obtained through Finite Integration Technique (FIT). Vector Fitting Method (VFM) is used here to construct a macromodel from tabulated frequency domain data. Resulting pole residue macromodel is directly embedded into HSPICE or compatible circuit solvers. In this paper, a systematic macromodeling methodology is discussed and a simple procedure for embedding the macromodel into circuit solver is described. Single ended via connected with two microstrip lines example shows the validity of the proposed methodology. |
| Authors: | Ashish Kalubhai Sarvaiya , Sanjeev Gupta |
| Submitted On: | 08/08/2014 |
| Pages: | 105-110 |
| Action: | [Full Paper]
No. of Downloads: 66 |
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| Manuscript Title: | Electromagnetic Scattering from an Inhomogeneous Array of Parallel Cylinders by the Method of Auxiliary Sources |
| Manuscript Id: | IJMOT-2014-9-629 |
| Abstract: | This paper proposes a rigorous solution for the electromagnetic scattering problem from an arrangement of an inhomogeneous long and axially parallel cylinders, illuminated by plane wave. Firstly, this solution is based on the application of the standard Method of Auxiliary Sources. Secondly, an optimization of the solution is introduced in order to minimize the computational cost and time. In order to check the validity of these two solutions, in the case of inhomogeneous array, the radar-cross section of some examples is calculated and compared with available data in the literature. |
| Authors: | Sami HIDOURI , Taoufik AGUILI |
| Submitted On: | 19/09/2014 |
| Pages: | 111-117 |
| Action: | [Full Paper]
No. of Downloads: 25 |
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| Manuscript Title: | Multiband Fractal Antenna for Mobile & Tablet PCs covering LTE, UMTS, GSM and WLAN Applications |
| Manuscript Id: | IJMOT-2014-11-649 |
| Abstract: | Revised cantor geometry based compact, low profile LTE fractal antenna is proposed here. The proposed antenna is appropriately covering several wireless applications, including GHz band, 2.3 GHz, 2.6 GHz and 2.9 GHz applications, WLAN 2.4 GHz and 5.8 GHz applications, GSM, UMTS, DCS, Zi applications. This antenna is designed analyzed using MATLAB code based on 3D FDTD method. Antenna finger dimensions are optimized using observations in MATLAB and CST Studio Suite. Radiation Patterns show almost omnidirectional behavior for all the observed frequencies with Directivity between dBi and Radiation Efficiency is within the range of -0.9 dB to -2.1 dB. Experimental results accurate matching with theoretical results. SAR is less than 1.7 W/kg for 10 g tissue, without mobile circuitry but full PCB and LCD film. |
| Authors: | Vivek Dhoot , Sanjeev Gupta |
| Submitted On: | 29/11/2014 |
| Pages: | 118-125 |
| Action: | [Full Paper]
No. of Downloads: 76 |
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| Manuscript Title: | FlexibleSolidStatePowerAmplifiers for Space use |
| Manuscript Id: | IJMOT-2014-9-630 |
| Abstract: | This work presents a simplified design of a Solid State Power Amplifier (SSPA) with varying RF output power (flexible SSPA) and its' new type of application for onboard application. For satellite applications, the uplink rain fading losses can be compensated with the help of the Automatic Level Control (ALC) technique by increasing the gain of the amplifier but the for downlink rain fading losses the output power of the power amplifier has to be increased. This can be achieved by the use of flexible SSPA to compensate the downlink rain fade losses. For satellite applications it is necessary to maximize power added efficiency in all operating conditions for reliable and cost effective operation. This is achieved by DC bias control of the power stages of the power amplifier to improve the overall power added efficiency. A remarkable improvement of the order of 5 % at 3 dB back off is achieved. As a part of recent developments on flexible payloads worldwide, the flexi TWTAs can be replaced by flexi SSPAs. |
| Authors: | R J Doshi , Deepak Ghodgaonkar , D K Singh , D K Das |
| Submitted On: | 24/09/2014 |
| Pages: | 126-131 |
| Action: | [Full Paper]
No. of Downloads: 25 |
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| Manuscript Title: | Analytically Characterization and Optimum Performance of Nonlinearly Distorted Coherent Optical OFDM Signals |
| Manuscript Id: | IJMOT-2014-9-622 |
| Abstract: | Nonlinear phase noise can severely degrade the performance of multicarrier optical signals by introducing both inband and out-of-band distortion. In this paper we study analytically the impact of nonlinear phase distortion on CO-OFDM (Coherent Optical Orthogonal Frequency Division Multiplexing) schemes with large number of subcarriers. By using the Bussgang theorem, we derive the power spectral densities of the useful and the distortion term of the nonlinearly distorted signal. The traditional approach in conventional CO-OFDM implementations is to treat nonlinear distortion as an undesirable noise term that leads to performance degradation. However, it can be shown that this distortion has information on the transmitted signals that can be used to improve the performance. Surprisingly, we show that the distortion inherent to the nonlinear phase noise can lead to performance improvements relatively to the ideal, linear CO-OFDM transmissions. We present a closed-form expression for the average asymptotic gain associated to the optimum detection of nonlinearly distorted CO-OFDM signals and we derive the approximated bit-error-rate using the distribution of the the asymptotic gain. |
| Authors: | João Guerreiro , Rui Dinis , Paulo Montezuma |
| Submitted On: | 07/09/2014 |
| Pages: | 132-142 |
| Action: | [Full Paper]
No. of Downloads: 31 |
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| Manuscript Title: | Characterization of Ghanaian Turbulent Atmospheric Channel for Free Space Optical Communication |
| Manuscript Id: | IJMOT-2104-8-615 |
| Abstract: | Free Space Optical (FSO) communica-tion is the transmission of optical signals through the atmosphere. This technology promises high wireless data rates, highly secured transmission, license-free operation and immunity to electro-magnetic interference. However, FSO reliability is decreased considerably by atmospheric conditions. In this paper, we characterize the Ghanaian at-mospheric channel for FSO communication based on visibility statistics. We use Kruse’s model to estimate atmospheric attenuation in Ghana. The probability of outage on an FSO link is computed to determine the availability of the link. Our re-sults show atmospheric attenuation as high as 150.95dB/km and 128.2316dB/km in the 850nm and 1550nm transmission window respectively. The average atmospheric attenuation in Ghana for 850nm and 1550 nm wavelengths is below 2dB/km. The prob-ability of encountering higher attenuation condi-tions is low. |
| Authors: | James Dzisi Gadze , Prince Anokye , Nana Kwasi Diawuo |
| Submitted On: | 07/08/2014 |
| Pages: | 143-150 |
| Action: | [Full Paper]
No. of Downloads: 27 |
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| Manuscript Title: | Damped Vibration Sensing Using Optical Fiber Resonator Method |
| Manuscript Id: | IJMOT-2014-7-597 |
| Abstract: | This paper presents a new method of multilongitudinal mode fiber laser (MLMFL) to detect damped vibrations. Single mode fiber (SMF), Erbium doped fiber (EDF), Fiber Bragg grating (FBG) and 3dB coupler form a resonant cavity. The source and the pump power is provided by 980nm pump source to the resonant cavity. The multilongitudinal modes are produced within the reflected bandwidth of FBG. Several beat frequency signals are produced by beating any two modes in the resonant cavity. With the applied damped vibrations, the strain experienced by the fiber changes the length of the cavity which changes the beat frequency. Thus by measuring the change in beat frequency of the resonant cavity the damped vibration frequencies are measured through proper calibration. From analytical simulations, the damped vibration frequencies are observed from 500 Hz to 3000 Hz while the experimental method shows damped vibration frequencies from 500 Hz to 2000Hz. The difference between simulation and experimental results is due to different methods used for generating damped vibration frequencies and demodulation techniques. |
| Authors: | Prachi Bhide , Banmali S. Rawat , Syam Challa , Jaromir Pistora |
| Submitted On: | 10/07/2014 |
| Pages: | 151-159 |
| Action: | [Full Paper]
No. of Downloads: 27 |
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