Pattern synthesis of timed antenna array with the exploitation and suppression of harmonic radiation

Abstract

SummaryThe pattern synthesis of timed antenna array with the exploitation and suppression of harmonic radiation is proposed in this paper. Timed arrays are the time‐domain alternatives of conventional antenna arrays, where an additional control parameter “time” is used to generate the desired time‐averaged radiation pattern. This additional control also comes with the inherent hindrance of harmonic radiation, generally considered as an undesired effect of time modulation. In this work, this hindrance is overcome with different objectives considering the exploitation and suppression of harmonic radiation of timed arrays. To demonstrate the exploitation of harmonic radiation, a simultaneous sum and difference pattern with reduced sidelobe suitable for monopulse tracking radar systems is obtained at the fundamental and the first harmonic frequency by an optimal subarrayed pulse splitting and shifting approach. Two separate cases, considering uniform and optimized static excitations along with the proposed subarrayed pulse sequence, are presented for the exhaustive analysis of the simultaneous multibeam pattern. To address the suppression of harmonic radiation, the sidelobe level (SLL) at the fundamental frequency and the sideband levels (SBLs) of higher‐order harmonic frequencies are simultaneously reduced. In this regard, a unique pulse shifting approach for the edge elements of the array, along with an optimal set of static excitations, is proposed to enhance the efficiency of the antenna system by reducing SLL and SBLs at the same time. Two uniquely defined cost functions are chosen to address the above‐mentioned objectives by exploiting and suppressing the harmonic radiation of timed arrays, which further increases the adaptability and reconfigurability of the array. A set of 16‐element “time‐modulated” linear array (TMLA) is considered for optimization, and a wavelet mutation‐based differential evolution (DEWM) algorithm is employed to obtain the optimal solutions. Obtained numerical results are reported and also compared with previously published works to show the proposed approach's potentialities.

Power leakage minimization in time‐modulated linear antenna array with optimized switching strategies employing modified harmony search algorithm

“…27 Further to improve the power radiated in fundamental frequency operations on the optimized time pulse are conducted, like shifting and splitting of time pulse. [28][29][30] To achieve the ultra-low SLL and SBL hybrid optimization algorithms are exploited, which report better results than conventional evolutionary algorithms. The hybrid algorithms PSO with wavelet mutation (NPSOWM), wavelet mutation-based DE (WMDE), and inverse weed optimization with convex optimization (CVXIWO) reported better results than the novel optimization for TMLAA.…”

“…The hybrid algorithms PSO with wavelet mutation (NPSOWM), wavelet mutation-based DE (WMDE), and inverse weed optimization with convex optimization (CVXIWO) reported better results than the novel optimization for TMLAA. 29,[31][32][33] With rapid evolutions in the optimizing world, new algorithms are emerging in the optimization world. One such algorithm inspired by the performance of the group of musicians is harmony search (HS).…”

Time-modulated linear array synthesis with optimal time schemes for the simultaneous suppression of sidelobe and sidebands

“…The potentialities of TMAs for beamforming [31,32] and beam steering [33,34] applications have been addressed with appropriate time sequences. TMAs for monopulse sumdifference patterns [35] and multi-harmonic steered patterns [36,37] have been discussed with controlled radiation properties. Multiple optimized patterns of TMAs [38] have also been generated for cognitive radios [39,40] and multiple-input multiple-output systems [41,42], which further enhances the diversity and multifunctional capabilities.…”

Design optimization of linear arrays and time‐modulated antenna arrays using meta‐heuristics approach

“…According to studies, very low or ultra-low SLLs with improved radiation properties can be obtained using uniformly or non-uniformly excited arrays by implementing adjustable switch configurations. [45][46][47][48][49][50] The ability to use TMLAs in emerging domains like tracking radar systems, 51,52 path-finding, 53 direction of arrival evaluation, 54 automatic beam steering, [55][56][57][58] and so on was made possible through elaborative research works in this field.…”