A novel magneto–electric dipole antenna with ultra-wideband and dual-polarized characteristics is proposed. In comparison with traditional magneto-electric dipoles, this antenna achieves a wider bandwidth by replacing the traditional “Γ” feeding structure with a stair-shaped one, and meanwhile using semicircle radiators rather than the commonly used rectangular ones. Such an antenna is designed, fabricated and measured. The measurement and simulation results agree well with each other, and demonstrate encouraging properties. For its two feeding ports, the impedance bandwidths with the Standing-Wave Ratio(SWR)≤2 impedance are up to 90.8%(2.06-5.37 GHz) and 84.4%(2.08-5.12 GHz) respectively, and moreover, over the whole working frequency band, the proposed antenna possesses both good directional radiation patterns and stable gains, e.g. the gains are (8.6±0.8) dBi and (8.85±0.85) dBi respectively for the two feeding ports.