A microstrip line-fed planar antenna with dual notched bands is designed and prototyped for ultrawideband (UWB) communication applications. The dual band-notch characteristic is achieved by etching a single tri-arm resonator below the patch. The simulated and experimental results show that the designed antenna has achieved a wide bandwidth (return loss ≤ -10 dB) ranging from 2.98 to 10.76 GHz with two notched bands operating at 3.5 and 5.5 GHz. The proposed antenna uses only one simple filter element to create and control dual notched bands, which give it advantages over the recently proposed band-notch antennas. In addition, the designed antenna achieved a good gain and exhibits omnidirectional radiation patterns except at notched bands, which make it a suitable candidate for UWB applications.