A compact multi-resonance antenna for wideband/ultra wideband applications

A simple multi-resonance antenna is introduced as an antenna element for designing wideband and ultra wideband (UWB) radiators. It consists of a quarter-wavelength monopole above a ground plane surrounded by a short cylinder. It is seen that in addition to the resonances of the monopole, there exist some resonances originating from the coaxial transmission line composed of the monopole and the cylinder around it. It is shown that by properly choosing of the structural parameters, the antenna can be used as a wideband or UWB radiator. In wide band application, the proposed antenna has a fractional bandwidth (S
₁₁
<;-10 dB) of 55% compared to the monopole antenna, 7.7%. For UWB application, the proposed antenna can cover the frequency band of 3.1-10.6 GHz.