A multiband conical monopole antenna derived from a modified Sierpinski gasket

The Sierpinski gasket monopole is known to exhibit a certain degree of periodic multiband behavior in terms of its input impedance characteristics. However, its overall performance properties are somewhat less than desirable. Specifically, the Sierpinski gasket monopole exhibits a relatively narrow bandwidth in each of its operating bands and its radiation patterns exhibit poor omnidirectionality because of the asymmetrical two-dimensional (2D) bow-tie shape of the antenna. Here, a multiband conical monopole antenna is presented that is designed to operate in the same frequency bands as the Sierpinski gasket. The conical monopole antenna, being a symmetrical three-dimensional (3D) structure, offers increased impedance bandwidth and improved radiation pattern performance.