Browsing by Author "LAKHLEF, Nora"

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    Etude et Optimisation des Réseaux d’Antennes Imprimées
    (Université de M'sila, 2021-11) LAKHLEF, Nora
    The present thesis deals with three essential problems found for wireless telecommunications applications. The first thematic concerns the problem of monitoring linear antenna arrays using grey wolf optimization method (GWO). When an abnormal event (fault) affects an array of antenna elements, the radiation pattern changes and significant deviation from the desired design pattern can occur. In this work, reconfiguration of the amplitude and phase distribution of the remaining working elements in a failed array is considered. This latter can improve the side lobe levels (SLL) and also maintain the main lobe in the desired direction. Simulation results clearly have shown the effectiveness of the proposed algorithm to monitor the failure correction of linear antenna arrays. The second problem deals with the synthesis of symmetrical and non-symmetrical linear antenna arrays using a new optimization technique, named as modified grey wolf optimization (MGWO) algorithm. The synthesis of circular antenna arrays using coco search technique is also considered. To matches the desired pattern as closely as possible, we considered the optimization of interspacing elements, weights amplitude and phase excitation of the linear antenna array. It has been demonstrated that the performance of a printed linear antenna array depends on all parameters, in which simultaneous optimization is imperative to maximize its characteristics. The obtained results show the effectiveness and the flexibility of the proposed algorithm in terms of minimized lateral lobe level and the convergence speed towards the desired solution compared to those of other techniques in the literature. The last research issue presented in this dissertation deals with the problem of designing rectangular patch antennas with two feeding techniques. To this end, we were simulated using the HFSS software two rectangular antennas operating at the frequency 2.4 GHz and 10 GHz respectively. The results of the simulation (as reflection coefficient…) show a shift between the frequencies required and the frequencies found. To remedy this problem, an analysis and a parametric study of this type of antennas has been carried out. This last allowed the frequencies to be brought exactly to the required ones. The optimized antennas are then networked with two elements fed in parallel and in series at a quarter waves respectively. In both cases, networking mainly increases gain and directivity.