Monopole antennas have been used in many applications, especially in HF antennas, due to their inherent advantage like simple structure, easy to machine and mount, and omnidirectional radiation pattern. However, in HF band, the band of the antennas is narrow, and the input impedance of monopole antenna with limited height undergoes rapid variation with frequency. In order to overcome the shortcomings of the monopole antennas, a methods of quasi-fractal is used, which decrease the resonant frequ...