Theses and Dissertations

Permanent URI for this collectionhttp://ir.daiict.ac.in/handle/123456789/1

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    ItemOpen Access
    GPU-accelerated method of moments
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Soni, Pushtivardhan; Zaveri, Mazad S.
    This work considers the use of commodity graphics processing units (GPUs) for accelerating run-time critical phase of method of moments (MoM) which is a widely used computational electromagnetic (CEM) technique for solving electromagnetic problems governed by an electric field integral equation (EFIE), and ideally suited for radiation and scattering problems. To this end, scattering analysis of metallic bodies with arbitrary shape using standard Rao-Wilton-Glisson (RWG) basis and weighting functions which is a good tradeoff between accuracy and complexity, is considered for the serial and parallel implementations. Among the phases of MoM—assembling impedance matrix and excitation vector, and solving matrix equation—impedance matrix assembly is the most compute intensive phase, and involves massive data-based parallelism; computation of each matrix element requires execution of a common program with unique data set. Therefore the impedance matrix assembly phase is subjected to the GPU acceleration using CUDA that supports single instruction, multiple data (SIMD) paradigm. The results computed shows a good agreement with the reference values computed with commercial software package such as FEKO. From the performance viewpoint, the GPU-based implementation shows a significant speedups over the CPU-only implementation. The linear growth of speedup with respect to number of CUDA threads used to compute matrix element conforms the scalability of the implementation, and indicates the feasibility of greater speedups for larger problems. The peak speedup for the impedance matrix assembly phase of MoM was measured to be about 30 that turn up about 4× faster execution when considering total MoM solution process for the problem and hardware considered. In addition, the comprehensive treatment of the scattering problem in functional analysis framework and the detailed implementation of MoM make this work useful for developing other accelerated implementations of other computational electromagnetic (CEM) methods (i.e., FDTD, FEM).
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    ItemOpen Access
    Design and analysis of multiband fractal antenna
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Dhoot, Vivek; Gupta, Sanjeev
    Miniaturized Multiband antenna design is an important and challenging task for communication industry. Several constraints like size, position of the antenna, feasibility, reflection coefficient, Specific absorption Rate (SAR), make it more difficult to design a multiband antenna. Current trend suggests that one device (Mobile, Tablet PCs etc.) should cover multiple communication applications (Like GSM, LTE, Bluetooth, Wi_ etc.). It implies that antenna design should not only satisfy the constraints but also cover wide multiband range. In this research work, design, analysis and measurement of fractal antennas, are carried out, for such multiband applications. Revised cantor geometry is proposed for antenna design, which produces more than 5 resonances in second iteration only (feasible design). The three dimensional Finite Difference Time Domain (3D-FDTD) Method is used for analyzing the reflection coefficient of the antenna. Revised cantor geometry based compact, low profile LTE fractal antenna is proposed here, for Mobile and Tablet PC applications. The proposed antenna is appropriately covering several wireless applications, including LTE 1.7-1.8 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, ZigBee, PCS, applications. This antenna is designed and 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, for all the observed frequencies, Directivity between 7.72 dBi to 8.17 dBi and Radiation Efficiency, within the range of -0.98 dB to -1.95 dB. Experimental reflection coefficient results present accurate matching with theoretical results. Theoretically analyzed SAR is less than 1.6 W/kg for 10 g tissue, without mobile circuitry. SAR reduction technique is also been presented.

    In addition to this, fractal antenna on substrate with high dielectric constant, fractal antenna array design and integrated antenna designs, are also studied, as part of this work.