Miniaturized ultra wideband fractal antenna

Space-filling curves have been used for the development of a miniaturized ultra wideband fractal wire monopole antennas. Several space-filling curves have been investigated and compared. Resistive loading has been used to achieve the ultra wideband performance. In addition, genetic algorithm has been applied to optimize both the values of the resistive loads and their positions. A multi-frequency cost function is implemented, where the cost function is a combination of VSWR and efficiency. A bandwidth of 108% (about 1.3GHz) centered at 1.2 GHz has been achieved using three resistances on a 2^nd iteration Hilbert wire monopole. The proposed ultra wideband 2^nd iteration Hilbert wire monopole antenna has a minimum radiation efficiency of 30% over the entire frequency band, and a maximum gain of 5.9dB. The proposed antenna has a footprint of only 7x7cm². Measurements of the antenna return loss has been performed and compared successfully with the simulation results. The design and simulation have been carried out using SuperNEC® electromagnetic simulator.