A low-profile, low cost reconfigurable antenna with on-demand single- or dual-band rejection capability for ultra-wideband (UWB) applications is presented. A modified monopole structure is integrated with an arc-shaped slot and two open-ended L-shaped stubs to realise the band rejection. The antenna operates in four modes: a full UWB (3.1-10.6 GHz) coverage antenna, a UWB antenna with a single-band WiMax or wide local area network (WLAN) rejection, and a UWB antenna with dual-band WiMax/WLAN rejection. On-demand individual and simultaneous band-rejections are implemented by controlling the arc-slot and L-stubs using three PIN diodes. Thus, the adopted control technique is quite easy and requires low operational power (approximately 40 mW max.). Details of the design process and reconfiguration mechanism are presented. The band-rejection function is explained using equivalent circuits and surface current distribution at each mode. A prototype is built on the FR4 substrate and tested to validate the performances. The antenna exhibits stable radiation characteristics and almost flat gain (average 4 dBi) responses across the whole band, while significantly weak radiation and gain reduction (;7 dB) are achieved at the rejected bands. Therefore, this antenna is suitable for high-performance UWB systems in WiMax/WLAN dense environments with the aim to improve signal quality, system capacity, and communication link efficiency.