Abstract
A new strategy of density tapering called the partial density tapering (PDT) accompanied with the algorithm of differential evolution (DE) is proposed to suppress the peak sidelobe level (PSL) of uniform excited concentric ring arrays (UECRA) with isotropic elements. Through performing the PDT, a sound starting solution for DE can be generated. Then, the ring filling factor (RFF) is introduced so that the optimization of the number of elements can be transformed into the optimization of RFFs within the tapered thresholds, and thereby the real coding can be directly used with respect to the consideration of parallel encoding strategy. Finally, the UECRA featuring improved PSL performance can be obtained by limited runs of conventional DE. Several numerical instances for UECRA, with aperture sizes ranging from small to large scale, confirmed the outperformance of the proposed method.
Highlights
For the capability of achieving rotationally symmetrical beam pattern, concentric ring array (CRA) had found the applications in radar, direction finding, radio-astronomy, satellite communications, and so on [1,2,3]. erefore, the synthesis for CRA had been a topic of considerable study by many investigators [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]
In literature [9], by utilizing the characteristics of first kind Bessel functions for representing the array factor, Kedar presented a technique for synthesis of wideband wide-scan uniform excited concentric ring arrays (UECRA) with low sidelobe level
We first divide the aperture of UECRA into M concentric rings, where a total of m0 rings (m0 is the nearest integer less than or equal to M/2) close to the center of the array are set to be equal-spaced, and the interspacings of remaining (M − m0) rings are set to be sequentially increased from the inside to the outside of the array. en, we initialize the element distribution of m0 inner rings to be fully populated, while the ring filling factor (RFF, defined as the ratio of the current number of elements of a ring to the number of elements when the ring is fully populated) of the rest rings are constrained by a proper tapered thresholds
Summary
For the capability of achieving rotationally symmetrical beam pattern, concentric ring array (CRA) had found the applications in radar, direction finding, radio-astronomy, satellite communications, and so on [1,2,3]. erefore, the synthesis for CRA had been a topic of considerable study by many investigators [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. According to the authors’ opinion, improving the quality of the initial solution is a reasonable way to speed up the convergence speed of the stochastic algorithms In view of this point and with the purpose of suppressing the PSL of UECRA with isotropic elements, a new strategy of density tapering, named partial density tapering (PDT), is proposed in this paper. For the elements located near the center of the array, the normalized excited amplitudes are almost equal and close to 1 For this reason, we first divide the aperture of UECRA into M concentric rings, where a total of m0 rings (m0 is the nearest integer less than or equal to M/2) close to the center of the array are set to be equal-spaced, and the interspacings of remaining (M − m0) rings are set to be sequentially increased from the inside to the outside of the array.
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