This paper presents a novel ultra-wideband (UWB) antenna that rejects narrow and broad bands and is suitable for wireless communications. The base of the proposed antenna has a circular patch that can cover the UWB frequency range (3.1~10.6 GHz). The interference issues caused by co-existence within the UWB operation frequency are overcome by a design that uses a parallel-coupled asymmetric dual-line with a circular monopole antenna. The proposed antenna showed a stable radiation pattern, realized gain and reflection coefficient lower than -10 dB across the UWB operation bandwidth except for 5.15~5.85 GHz and 7.25~8.4 GHz. The fabrication, simulation, and measurement results obtained for the proposed antenna were in good agreement with the expected values.