A compact and wideband balance-fed triangular-monopole antenna is newly proposed in this article for modern wireless applications. This balance-fed antenna is for microstrip-feeding with differential signals. The antenna is compact in size and has the attractive merit of insensitivity to the influence of size variation of the feed ground. A prototype of the antenna having adequate bandwidth for the DCS, PCS, UMTS, WL4N, and WiMAX bands was constructed and is shown. The simulated and measured results of its return loss and antenna patterns demonstrate the sufficient impedance-matching bandwidth and omnidirectional radiation characteristic of the newly developed antenna, together with the attractive merit mentioned earlier. (C) 2008 Wiley Periodicals, Inc.