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Evolutionary optimization of zig-zag antennas using Gaussian and multiquadric radial basis functions

Zig-Zag monopole antennas are frequently used and are of great importance in HF and VHF communications. Their shapes provide addition of wire length and thus contribute to inductive loading. Structural variations of the zig-zag shape are explored in this paper to change the distribution of inductance along the monopole height and thus improve the antenna performance. These variations are represented using radial basis functions to lower the number of variables in the optimization process. Evolutionary optimizers are applied to obtain the optimal shape variations based on electromagnetic simulations. The performance is considered with respect to bandwidth and radiation efficiency with a matching network tuned at the target frequency. Prototypes of the optimized zig-zag antennas are fabricated, measured and compared to a uniform zig-zag monopole. Experiments indicate a good agreement to the optimal simulation results.