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A method of using particle swarm optimisation (PSO) algorithms to optimise the element spacing and lengths of Yagi--Uda antennas is presented. SuperNEC, an object-oriented version of the numerical electromagnetic code (NEC-2) is used to evaluate the performance of various Yagi--Uda antenna designs. In order to show the capabilities of the PSO algorithm in Yagi--Uda antenna design, three different antenna design cases are optimised for various performance specifications. The three objectives considered are gain only, gain and input impedance only, and gain, input impedance and relative sidelobe level (rSLL). To alleviate the premature convergence problem of PSO, a novel learning strategy is employed. Each design problem is optimised using three variants of PSO algorithms, namely the modified PSO, fitness-distance ratio PSO (FDR-PSO), and comprehensive learning PSO (CLPSO). For the purpose of comparison and benchmarking, equally spaced arrays, genetic algorithm optimised antenna design, and computational intelligence optimised antenna design are considered. The results clearly show that the CLPSO is a robust and useful optimisation tool for designing Yagi antennas for the desired target specifications. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel mixed-integer optimization formulation for the optimal design of a reconfigurable antenna array with quantized phase excitations, which is solved by using the generalized generation gap (G3) model genetic algorithm (GA). To reduce effect of mutual coupling between the antenna-array elements, the amplitude excitations' dynamic-range ratio is minimized. The simulation experiments* clearly show an improved performance of the discrete realization of the phase-excitation values, as compared to the continuous realization and subsequent quantization. The effect of quantization on the continuous formulation of phase excitations is also demonstrated. The proposed mixed-integer formulation can be used in practice for the optimal design of dual-beam antenna arrays. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 461–465, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20853 [ABSTRACT FROM AUTHOR]