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This paper presents a wire antenna for multi-band WLAN application, having a very simple geometry, designed using the StructureBased Evolutionary Programming; an innovative antenna design technique, based on evolutionary programming. The chosen fitness function includes far-field requirements, as well as wideband input matching specifications. The latter requirements, which must be present in every useful antenna design, allow to stabilize the algorithm and to design both optimal and robust antennas. The antenna has been analysed with NEC-2 during the evolutionary process and the outcome of the procedure shows a very good performance; with a -10dB bandwidth that covers the required frequencies for multi-band WLAN applications (2.4/5.2/5.8 GHz) and beyond, and an end-fire gain greater than 10 dB. The NEC-2 results have been also compared to the ones obtained by a well-assessed, general purpose, 3D electromagnetic software, HFSS by Ansys, showing a very good agreement.

The paper shows how precisely one can model Yagi antenna for WLAN with all accompanying elements (dielectric carrier, U-balun, radome), and how these elements influence the antenna characteristics. The investigation is based on simulation of a typical high gain Yagi antenna and comparison these results with measurements. It is found that dielectric carrier can be omitted from analysis, U-balun should be included for reflection coefficient results, while influence of radome is significant for both reflection coefficient and radiation pattern.