A Novel Broadband Eighth-Wave Conical Antenna

A novel antenna is composed of a conical monopole with metallic parasitic elements and a capacitive disk placed above a ground plane. A dielectric substrate is used in order to optimize the performances. This antenna provides broadband characteristics and omnidirectional radiation patterns over the whole bandwidth with a height limited to a one eighth wavelength associated to the lowest frequency. Simulations and experiments demonstrate that this structure exhibits a 2.9:1 impedance bandwidth with VSWR below 2:1 and very good radiation patterns and gain in spite of a size extremely reduced.