volume | PIER Journals

Abstract

Usually inactive or also known as thinned elements are used to simplify the array design complexity by turning off some of the active elements in uniformly filled arrays. Consequently, the far-field radiation characteristics such as sidelobe level, beamwidth, and directivity may be negatively changed if no optimizer is used. Further, these radiation characteristics may be unavoidably deteriorated when the main beam is scanned to new directions other than the referenced broadside direction. In this paper, an efficient optimization method based on the genetic algorithm and a dynamic deactivation method is proposed to randomly deactivate a number of array elements to minimize the peak sidelobe level and at the same time maintain the array directivity undistorted, while scanning the main beam. The deactivation method chooses optimally the suitable number of elements and their locations that need to be deactivated such that the resulting radiation characteristics positively change according to the specified cost function. Also, the proposed scanned array uses binary coefficients to activate and deactivate the array elements, thus, the feeding network of the proposed array is very simple, and it can be easily implemented in practice. Through extensive simulation results, we show that the proposed optimization method has good performance under wide range of scanned main beam directions. It is also found that the number of deactivation elements (i.e., the optimization variables) increases with larger scan angle.

1. Mohammed, Jafar Ramadhan, "An optimum side-lobe reduction method with weight perturbation," Journal of Computational Electronics, Vol. 18, No. 2, 705-711, 2019.

2. Abdulqader, Ahmed Jameel, Jafar Ramadhan Mohammed, and Raad H. Thaher, "Phase-only nulling with limited number of controllable elements," Progress In Electromagnetics Research C, Vol. 99, 167-178, 2020.

3. Mohammed, Jafar Ramadhan, "Phased sub-arrays pattern synthesis method with deep sidelobe reduction and narrow beam width," IETE Journal of Research, Vol. 69, No. 2, 1081-1087, Dec. 2020.

4. Mohammed, Jafar Ramadhan and Karam Mudhafar Younus, "Null steering implementation by controlling side-elements positions," International Journal of Microwave and Optical Technology, Vol. 16, No. 6, 568-575, Nov. 2021.

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6. Mohammed, Jafar Ramadhan, "A new antenna array pattern synthesis method with sidelobe control," Journal of Telecommunication, Electronic and Computer Engineering (JTEC), Vol. 10, No. 3, 31-36, Jul.-Sep. 2018.

7. Mohammed, J. R., "Optimal null steering method in uniformly excited equally spaced linear arrays by optimising two edge elements," Electronics Letters, Vol. 53, No. 13, 835-837, Jun. 2017.

8. Mohammed, Jafar Ramadhan, "Element selection for optimized multiwide nulls in almost uniformly excited arrays," IEEE Antennas and Wireless Propagation Letters, Vol. 17, No. 4, 629-632, Apr. 2018.

9. Mohammed, Jafar R., "A method for thinning useless elements in the planar antenna arrays," Progress In Electromagnetics Research Letters, Vol. 97, 105-113, Apr. 2021.

10. Haupt, Randy L., "Adaptively thinned arrays," IEEE Transactions on Antennas and Propagation, Vol. 63, No. 4, 1626-1632, Apr. 2015.

11. Mohammed, Jafar Ramadhan, "Beam-pattern control via thinned elements strategy in linear and planar phased arrays," Progress In Electromagnetics Research Letters, Vol. 111, 79-84, Jul. 2023.
doi:10.2528/PIERL23022403

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Dr. Noor Waadullah Yaseen

Prof. Jafar Ramadhan Mohammed