volume | PIER Journals

Abstract

Generally, the array pattern synthesizing can be shaped by controlling the excitation amplitude and phase of the individual elements of the antenna array which they could be controlled either separately or jointly to provide most flexible solutions for the desired pattern shaping. In this paper, a new controllable trapezoid phase-only taper is proposed. In practical applications, phase-only tapers are more preferable than amplitude-only tapers due to their desirable advantages. The required pattern shaping with fulfilled user-defined constraints on the sidelobe peaks, beam widths, and steered nulls can be achieved by optimizing only the excitation phases of the trapezoidal taper. More importantly, the proposed trapezoidal taper offers the best tradeoff between the array directivity and undesirable sidelobe pattern. In addition, the element excitation amplitudes of the proposed phase-only trapezoid taper are made constant and equal to that of the original trapezoid taper function. Thus, it enjoys low array complexity. Moreover, the manipulated phases are assumed to be symmetric to further simplify the array feeding network. The genetic algorithm was used to optimize only the half number of the elements' phases. The results show that the phase-only trapezoid taper yields identical main beam shape to that of the amplitude-only trapezoid taper and much better than the other conventional tapers. Furthermore, it is found that the trapezoid phase-only method needs more variable elements than the trapezoid amplitude-only method to achieve almost the same performance. Thus, the complexity reduction percentage of the phase-only method is lower than that of the amplitude-only method.

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Prof. Jafar Ramadhan Mohammed