A novel design of a dual-polarized broadband 2-18GHz horn antenna with VSWR (Voltage Standing Wave Ratio) less than or equal to 2.2 is presented. The designed horn antenna is most suitable as a feed element in reflectors of the radar systems and EMC (ElectroMagnetic Compatability) applications. A coaxial line to quadruple-ridged waveguide transition with a new conical cavity back and a technique for tapering the flared section of the horn is introduced to improve the return loss and matching of the impedance, respectively. In order to overcome the deterioration of the broadside radiation pattern at higher frequencies, common to broad band ridged horn antennas, a new modified horn antenna with arc shaped aperture is introduced.