A Novel Broadband Modified Monopole by the Use of a Parasitic Conical Skirt

Parasitic structures around a narrowband antenna may lead to significant bandwidth broadening. For instance, staircase metallic rings around a monopole antenna have been successfully used recently, yielding an impedance bandwidth increase by a factor of close to 10. In this letter, a conical metallic skirt is proposed as the parasite instead. The technique has been assessed with the aid of electromagnetic analysis software. A prototype for operation at the 1.5–4.5-GHz band was assembled and measured. The bandwidth increase is around 0.4 GHz greater than the one obtained with parasitic rings.