A new design about planar triangular monopole antenna using a modified ground plane for bandwidth enhancement is proposed. By symmetrically etching a pair of modified L-shaped slots in the ground plane, the impendence bandwidth is increased to 2.5-10.8 GHz under the condition of VSWR<2. Comparing with the original antenna (not slotted), the operating band of the proposed antenna is largely expended, whereas good radiation characteristics hold. The measured and simulated results show that the operating band of the proposed antenna completely covers the frequency range of ultra-wide band (UWB). (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53: 1818-1820, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26100