Load sensitivity analysis for genetically engineered miniature multiband fractal dipole antennas

A powerful design tool has recently been developed for the optimization of fractal antenna elements (FAE) that combines the robustness of genetic algorithms (GA) with the versatility of iterated function systems (IFS). In particular, the GA-FAE design scheme introduced by D.H. Werner et al. (see Proc. IEEE Antennas and Propagation Society Int. Symp., vol.3, p.628-31, 2001; IEE Electronics Letters, vol.37, no.19, p.1150-1, 2001) employs a GA to select the optimal self-affine fractal geometry of the antenna as well as the load locations and load component values required for multiband operation. Performance discrepancies were observed between simulations and measurements made on several prototype loaded FAEs. This has been partly attributed to the difference between the component values assumed in the simulations and the actual values of the components used in the prototype antennas. This observation provided motivation for a sensitivity analysis to be performed on the load component values of these antennas. As a consequence of this study, several new optimization approaches have been developed which lead to antenna designs with considerably reduced load sensitivity.