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Now showing items 65 - 80 of 162

  • Bandwidth enhanced metamaterial embedded inverse L-slotted antenna for WiFi/WLAN/WiMAX wireless communication

    Hasan, Md. Mehedi   Rahman, Maskia   Faruque, Mohammad Rashed Iqbal   Islam, Mohammad Tariqul  

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  • A memory-based gravitational search algorithm for enhancing minimum variance distortionless response beamforming

    Darzi, Soodabeh   Kiong, Tiong Sieh   Islam, Mohammad Tariqul   Soleymanpour, Hassan Rezai   Kibria, Salehin  

    This paper introduces a memory-based version of gravitational search algorithm (MBGSA) to improve the beamforming performance by preventing loss of optimal trajectory. The conventional gravitational search algorithm (GSA) is a memory-less heuristic optimization algorithm based on Newton's laws of gravitation. Therefore, the positions of agents only depend on the optimal solutions of previous iteration. In GSA, there is always a chance to lose optimal trajectory because of not utilizing the best solution from previous iterations of the optimization process. This drawback reduces the performance of GSA when dealing with complicated optimization problems. However, the MBGSA uses the overall best solution of the agents from previous iterations in the calculation of agents' positions. Consequently, the agents try to improve their positions by always searching around overall best solutions. The performance of the MBGSA is evaluated by solving fourteen standard benchmark optimization problems and the results are compared with GSA and modified GSA (MGSA). It is also applied to adaptive beamforming problems to improve the weight vectors computed by Minimum Variance Distortionless Response (MVDR) algorithm as a real world optimization problem. The proposed algorithm demonstrates high performance of convergence compared to GSA and Particle Swarm Optimization (PSO). (C) 2016 Elsevier B.V. All rights reserved.
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  • An Octagonal Ring-shaped Parasitic Resonator Based Compact Ultrawideband Antenna for Microwave Imaging Applications

    Hossain, Amran   Islam, Mohammad Tariqul   Almutairi, Ali F.   Singh, Mandeep Singh Jit   Mat, Kamarulzaman   Samsuzzaman, Md.  

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  • Synthesis, Characterization and Development of Energy Harvesting Techniques Incorporated with Antennas: A Review Study

    Ibrahim, Husam Hamid   Singh, Mandeep S. J.   Al-Bawri, Samir Salem   Islam, Mohammad Tariqul  

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  • Effect of Solvent Vapor on the Morphology of Fluorinated Block Copolymer Films from Different Casting Solvent

    Islam, Mohammad Tariqul   Jeong, Yeon Tae   Gal, Yeong Soon   Park, Jong Myung   Lim, Kwon Taek  

    Poly(ethylene oxide)-b-poly(1H,1H-dihydroperfluorooctyl methacrylate) (PEO-b-PFOMA) micellar films were cast from chloroform or alpha, alpha, alpha-trifluorotoluene (TFT) with different copolymer concentrations, followed by TFT or PF-5080 vapor treatment. Though their initial morphologies were different, finally the same patterns were obtained under TFT or PF-5080 vapor with varying the annealing time. The time dependent phase behavior was examined at different stages.
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  • Left-handed metamaterial bandpass filter for GPS, Earth Exploration-Satellite and WiMAX frequency sensing applications

    Alam, Md. Jubaer   Ahamed, Eistiak   Faruque, Mohammad Rashed Iqbal   Islam, Mohammad Tariqul   Tamim, Ahmed Mahfuz   Maktoomi, Mohammad  

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  • Semi-fluorinated Block Copolymer Directed Ordering of Gold Nanoparticles in Thin Films via Solvent Vapor Annealing

    Islam, Mohammad Tariqul   Islam, Md Rafiqul   Park, Chan   Kim, Hyun Gyu   Gal, Yeong-Soon   Lim, Kwon Taek  

    The block copolymer thin films were prepared by spin casting micellar solutions of poly(ethylene oxide)-b-poly(1H, 1H dihydroperflurooctyl methacrylate)(PEO5k-b-PFOMA(22k)) in chloroform with or without gold salts. Upon fluorinated solvent vapor annealing, the disordered morphology of as-casted PEO5k-b-PFOMA(22k) thin films was changed to the phase inverted ordered morphology of spherical PEO cores in PFOMA continuous phase. The phase inversion strategy of the solvent annealing was found to enhance the long-range positional ordering of the thin films. The results suggest that an organized pattern of gold nanoparticles could be afforded inside the PEO domains of the hybrid thin films.
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  • Design and performance analysis of small-sized multiband microstrip patch antenna on custom-made biopolymer substrate

    Ahsan, Md Rezwanul   Islam, Mohammad Tariqul   Ullah, Mohammad Habib  

    This paper presents a simple design analysis and performance evaluation of rectangular, slotted, microstrip feed patch antenna. The design processes are performed by employing the finite element method (FEM)-based commercial EM simulation software High-Frequency Structural Simulator (HFSS). The proposed multiband antenna is composed of a rectangular, slotted radiator formed with four arc slots and central square slot, reduced ground plane, and microstrip line for feeding. The patch antenna is excited through the standard 50 Omega RF transmission line, impedance-compliant SMA connector that is connected to the microstrip line. The optimal parametric dimensions from the numerical simulations are used for constructing the physical prototype on a custom-made, ceramic-filled biopolymer substrate of epsilon(r) =3D 10.0. Based on simulation results, the experimental data are collected, analyzed, and compared; the surface current distributions on the patch, gain, and radiation patterns are critically discussed. The measured results show the impedance bandwidths for S11 less than -10 dB are 712 MHz at 0.788 GHz band, 1.38 GHz at 3.34 GHz band, and 2.46 GHz at 8.01 GHz band. The good radiation pattern performances, almost stable gain over the bands, and appreciable bandwidths recommend the antenna for operating in RFID, WiMAX, and C/X-band applications.
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  • Design and analysis of a complementary split ring resonator (CSRR) metamaterial based antenna for wideband application

    Islam, Sikder Sunbeam   Alam, Touhidul   Faruque, Mohammad Rashed Iqbal   Islam, Mohammad Tariqul  

    In this article, a compact complementary split ring resonator (CSRR) based double-negative (DNG) metamaterial antenna is presented for wideband (4.49 GHz-21.85 GHz) wireless application. The antenna is incorporated with a DNG metamaterial patch: 50 Omega microstrip feed line and partial ground plane. The antenna shows measured fractional bandwidth of 131.81% with a compact size of 0.37 lambda x 0.37 lambda x 0.01 lambda. The commercially available finite integration technique (FIT)-based simulation software, computer simulation technology (CST) microwave studio was adopted to investigate the performance of the proposed antenna. Several parametric studies were performed to investigate the effect of key structural parameters on antenna performances. The double-negative characteristics of the metamaterial were investigated as well.
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  • Constitutive parameter analysis of left-handed dual-star split-ring resonator metamaterial for homogeneous infinite slab

    Ullah, Mohammad Habib   Uddin, Md Jasim   Latef, Tarik Abdul   Mahadi, Wan Nor Liza   Ahsan, Md Rezwanul   Islam, Mohammad Tariqul  

    A new shaped backward wave periodic dual-star split-ring resonator (DSSRR) is proposed based on the equivalent transmission line theory. The proposed artificial DSSRR design structure produces a wide band from 7.5 to 9.5 GHz, and very high rejection (47 dB) with sharp cut-offs in the forbidden band. To ensure the retrieval of electromagnetic parameters, primarily a single unit cell is considered. Then, the periodic four unit cells are decomposed to investigate the excitation metamaterial properties. The constitutive properties of the dispersion diagram exhibited very unusual characteristics and separated into different directions in balanced and unbalanced conditions in order to excite propagation in different modes. The dispersion of left-handedness group velocity exhibits the parallel direction of the poynting vector and high gain in higher frequency regions, whereas the phase velocity demonstrates the anti-parallel direction of the poynting vector obtained from the resonance frequency regions. The overall electromagnetic parameters of negative dielectric constant, resonance permeability, anti-parallel phase and group velocity, and refractive index confirm that the proposed periodic DSSRR artificial structure to be the most suitable for metamaterial behaviour and characteristics.
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  • Sol-gel synthesis of transition-metal doped ferrite compounds with potential flexible,dielectric and electromagnetic properties

    Rahman, Ashiqur   Islam, Mohammad Tariqul   Singh, Mandeep Jit   Misran, Norbahiah  

    A compact and flexible dielectric substrate with efficient electromagnetic performances both in flat and bending conditions are presented in this paper. The proposed substrates, for potential microwave radiator applications have been fabricated from Mn doped zinc ferrite compounds by sol-gel method. Prepared MnxZn(1-x)Fe2O4, (x =3D 0.0, 0.2, 0.4, 0.6, 0.8) substrates were analysed structurally by X-ray diffraction spectroscopy and morphologically studied by scanning electron microscopy. We studied the optical and dielectric properties in the microwave range to evaluate the new material as a dielectric substrate for microwave applications. The prepared flexible substrates exhibit high dielectric permittivity and low dielectric loss in the microwave frequency range. For the proof of concept, the electromagnetic performances both at flat and bending conditions were verified by loading an electromagnetic radiator. We report the detailed measured performances of the reflection coefficient below -10 dB, average efficiency above 73% and average realized gain above 1.5 dBi within the operational bandwidth for the first time. The measured stable omnidirectional radiation patterns both in flat and bending conditions also confirm the potential of the proposed material to be used as a new flexible dielectric substrate.
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  • Evaluation of three immunological tests for the diagnosis of pulmonary tuberculosis in a rural endemic area of Bangladesh

    Islam, Mohammad Tariqul   Rabbi, Fazle   Ferdous, Shameema   Parvin, Ummey Shahnaz   Hossain, Akram   Hossain, Mohammad Sorowar  

    Abstract Objective Bangladesh is a high tuberculosis burden country. It is always challenging to diagnose active pulmonary tuberculosis (PTB) cases in rural areas where the setting up of conventional microscopic and cultural diagnostic tools is difficult. The objective of the present study is to find a feasible, reliable and easily accessible alternative diagnostic approach for PTB in the rural areas of Bangladesh. Methods A total of 86 sputum samples were collected from clinically suspected PTB patients of Anantapur village, an underdeveloped remote area of Netrokona district, Bangladesh. Sputum samples were screened by Ziehl-Neelsen (Z-N) and fluorescence staining methods and were categorized as smear-positive active PTB cases (n = 50) and smear-negative controls (n = 36); then the performance of three popular immunological tests were evaluated, including ICT, ELISA and Mantoux tests (MT). Results The sensitivity of ICT, ELISA, and MT (10 mm induration size) was 68%, 84% and 96%, respectively, and the specificity of these tests was 94.4%, 80.6% and 52.8%, respectively. When the cut-off size of induration in MT was changed from 10 to ⩾15 mm, the sensitivity and specificity of MT became 92% and 83.3%, respectively. It was also found that the interpretation of MT was not significantly affected by BCG vaccination when ⩾15 mm induration was taken as a cut-off value. Conclusion Considering the resource-constraints of rural and remote areas, the Mantoux test could be an alternative tool for the diagnosis of active PTB.
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  • A Comparative Study of the Effects of Substrate Composite Materials on External and Internal Handset Antenna EM Absorption

    HOSSAIN, Md Ikbal   FARUQUE, Mohammad Rashed Iqbal   ISLAM, Mohammad Tariqul  

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  • A Spectrally Efficient Macrodiversity Handover Technique for Interference-Limited IEEE 802.16j Multihop Wireless Relay Networks

    Sultan, Jamil   Misran, Norbahiah   Ismail, Mahamod   Islam, Mohammad Tariqul  

    In this paper, we propose an efficient macrodiversity handover (MDHO) technique for time-division-based interference-limited IEEE 802.16j multihop wireless relay networks. In the proposed MDHO, when the diversity set members of the mobile station (MS) are a base station (BS) and relay station (RS), the MS receives the signal transmitted by the BS in the first phase. During the second phase, it also receives the simultaneous transmissions of the BS and RS. Furthermore, when the diversity set members are two RSs or two BSs, the MS receives only the simultaneous transmissions of the diversity set members. The superiority of the proposed MDHO is validated using analytical and simulation results. The performance analysis metrics are the average downlink (DL) carrier to interference and noise ratio (CINR), the average DL spectral efficiency, and the average service outage probability. Evaluation results show that the proposed MDHO significantly outperforms the conventional MDHO. The CINR gain achieved using the proposed MDHO is 4.71 dB compared to the conventional MDHO.
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  • Detection of Salt and Sugar Contents in Water on the Basis of Dielectric Properties Using Microstrip Antenna-Based Sensor

    Islam, Mohammad Tariqul   Rahman, Md. Naimur   Singh, Mandeep Singh Jit   Samsuzzaman, Md.  

    This paper presents a microstrip antenna-based sensor for detecting salt and sugar in water. The patch antenna is low-cost and low-profile and is modeled to transmit and receive an electromagnetic signal. The presented antenna consists of a crescent-shaped patch and slotted partial ground. The compact size of the antenna is 32 mm X 22 mm. High-frequency structure simulator and computer simulation technology are used to simulate and analyze the characteristics of the antenna. The presented antenna achieves a 10 dB return loss from 2.50 to 18 GHz with 6.10 dBi of maximum gain, considerable efficiency, and consistent radiation patterns. The presented antenna is used as a sensor to detect salt and sugar in water in terms of reflection coefficient based on the dielectric properties of the solution. The percentage of salt and sugar in water changes the dielectric properties of the solution and the reflection coefficients subsequently. Results during the practical observations show that the reflection coefficient decreases with the increment of salt and sugar contents in the solution. With the excellent basic wideband antenna performances, the antenna shows good sensitivity to detect salt and sugar content in water. The presented antenna is suitable to be used in wideband wireless communications as well as wideband sensor applications.
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  • Effect on structural,optical and dielectric properties of mixed (1-x)ZnFe2O4-xSiO(2) as microwave dielectric ceramic material

    Zulfakar, Mohd Syafiq   Abdullah, Huda   Jalal, Wan Nasarudin Wan   Islam, Mohammad Tariqul  

    Samples of (1 - x)ZnFe2O4-xSiO(2) with different compositions have been prepared using sol-gel method. The morphological structures of the samples were analyzed using AFM and XRD analysis. AFM images show the surface roughness of the produced samples and indicate the surface roughness increased as the compositions of x increased where the average surface roughness to be around 0.30-1.34 nm. XRD analysis indicates the phase formation of cubic structure where dominant peak has been observed with Miller indices (311) at 35.25A degrees. The average crystallite size, D for dominant peak has been calculated with average size to be around similar to 10 nm. The FTIR analysis indicates the formation of spinel structure for ZnFe2O4 and also the presence of H2O molecules inside the samples. The fabricated patch antenna for samples (x =3D 0.05, 0.15 and 0.25) gives a good response in return loss analysis which are (>-10 dB).
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