Abstract: A kind of high-power coplanar-feed impulse radiating antenna (IRA) is described in this paper. It is constructed of four electrically large coplanar arms, and a 2.1 m diameter paraboloid reflector. To get higher gain, the point feed was fixed at the reflector focus. To figure out the high power feed problem, a kind of new high power balun was introduced, with conical input to 4 points output. The high-power coplanar-feed IRA was fabricated and the farfield was measured. The results show that: with 450 ps pulse width, 142 kV peak voltage short pulse input, the rE value could reach 800 kV.