A compact dielectric impulse radiating antenna (IRA) with flat coplanar conical plate (CCP) feed arms was proposed for low‐frequency gain enhancement. An empirical equation was proposed to predict the characteristic impedance of the CCP arms submerged in a dielectric half‐space. The predicted value was used to determine the termination resistors that connect the feed arms to the reflector. Both the dielectric‐filled and conventional air‐filled IRAs were fabricated, and their performances were measured. The gain of the proposed dielectric‐filled IRA is shown to be higher at frequencies lower than 3 GHz, where the diameter of the reflector is one wavelength.