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    IFT and Chebyshev-based planar array thinning for adaptive interference suppression
    (Springer, 2023) Agha, Maryam H.; AL-Adwany, Maan A. S.; Bayat, Oguz; Hamdoon, Hind Th.
    Smart antenna arrays with adaptive nulling capability are emerging as a promising solution to suppress the interference in radar applications and wireless communications in real time. Many adaptive nulling methods have been commonly used, such as controlling amplitude or/and phase excitations of the antenna elements and controlling the position of the elements. Generally, most adaptive nulling methods demand digital beamforming to create the correlation matrix from signals that arrived to array antennas. The digital beamforming is costly and needs frequent calibration; therefore, it does not appropriate for large antenna arrays. Among adaptive nulling methods, an array thinning does not require digital beamforming. It takes advantage of the adaptive algorithm to make the element active or inactive. In this paper, an IFT and Chebyshev techniques-based random thinning is presented to suppress the interference adaptively by lowering the SLL or place nulls toward the interference direction. The proposed method works with the antenna arrays that have transmit/receive modules (TRM) with RF switches. The results show the ability of both IFT and Chebyshev techniques to suppress the interference for the small array. In addition, the results indicate the superiority of IFT technique over Chebyshev in the large arrays; it is considerably faster and more efficient (in terms of lowering the sidelobe levels and nulls formation) than the Chebyshev technique. The advantage of the proposed method is no digital beamforming is needed. Consequently, a considerable reduction in complexity, power consumption, and cost can be attained.
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    Optimization of antenna array pattern for uniformly excited rectangular array via thinning
    (King Saud University, 2021) Agha, Maryam H.; Al-Adwany, Maan A.S.; Bayat, Oğuz; Th., Hamdoon, Hind
    Antenna arrays have a wide variety of uses, such as radar, military systems, and wireless communications. The performance of communication system depends heavily on the antenna arrays designing. The major challenges in designing such arrays are the high sidelobe levels and the enormous number of elements. Recently, the optimization techniques that exploit the evolutionary algorithms have been used extensively for thinning the antenna arrays with the aim of reducing the power consumption and improving the radiation pattern by decreasing the sidelobe levels. However, due to the stochastic nature of the resolution algorithms, the achievement of a global optimal for such algorithms is not assured. Based on the combination theory, this paper adopts an element by element removing strategy for thinning planar arrays. Without loss of generality, a uniformly excited 25 elements rectangular array with isotropic elements is investigated as an example. The proposed thinning method examines all the possible arrangements of the placements of 25 elements in the phased array aperture. In order to achieve the desired characteristics of radiation pattern, the optimum position of elements is selected. The results show that with the 40% thinning percentage, the same radiation pattern for the full array (without thinning) could be achieved. Consequently, a considerable reduction in resources usage can be attained in terms of power consumption, the number of phase shifters, and the number of attenuators. © 2021 The Authors