A low-profile ultra-wideband blade monopole antenna, which enclosed in a radome, at 400-3000 MHz bands is presented. The antenna configuration is a blade with slanted edge which demonstrates the enhanced impedance bandwidth compared with a blade antenna with equal total height but no slanted edge. The simulated and tested Voltage Standing Wave Ratio of the antenna along with the radiation patterns and gain are in good agreement. The proposed structure represents worthy performance despite its simplicity. The antenna matching performance shows VSWR <; 2.5 in the proposed frequency range. The antenna gain is reached to a peak of about 9 dBi at 2000 MHz and gain > 0 dBi is observed in the entire band.