DESIGN OF TIME-MODULATED LINEAR ARRAYS WITH A MULTI-OBJECTIVE OPTIMIZATION APPROACH

This article proposes a Multi-objective Optimization (MO) framework for the design of time-modulated linear antenna arrays with ultra low maximum Side Lobe Level (SLL), maximum Side Band Level (SBL) and main lobe Beam Width between the First Nulls (BWFN). In contrast to the existing optimization-based methods that attempt to minimize a weighted sum of SLL, SBL, and BWFN, we treat these as three distinct objectives that are to be achieved simultaneously and use one of the best known Multi- Objective Evolutionary Algorithms (MOEAs) of current interest called MOEA/D-DE (Decomposition based MOEA with Difierential Evolution operator) to determine the best compromise among these three objectives. Unlike the single-objective approaches, the MO approach provides greater ∞exibility in the design by yielding a set of equivalent flnal solutions from which the user can choose one that attains a suitable trade-ofi margin as per requirements. We compared time-modulated antenna structures with other methods for linear array synthesis such as the excitation method and the phase-position synthesis method on the basis of the approximated Pareto Fronts (PFs) yielded by MOEA/D-DE and the best compromise solutions determined from the Pareto optimal set with a fuzzy membership- function based method. The flnal results obtained with MOEA/D-DE were compared with the results achieved by two state-of-the-art single objective optimization algorithms and flve other MO algorithms. Our simulation studies on three instantiations of the design problem re∞ect the superiority of the MOEA/D-DE based design of time-modulated linear arrays.