The characteristics of the coaxial binary excilamps containing two exciplexes of XeCl * and XeBr * were studied based on the dielectric barrier discharge with various annular gap, driven by sinusoidal electronic control gear. The effect of the gas pressure, halogen fraction, and discharge gap were investigated. The optimum total pressure is 150-200 mbar and 200-250 mbar for 308 nm and 282 nm, respectively, leading to about 200 mbar for the total radiant efficiency. The optimized total halogen percentage is in range of 0.2%-0.3%, which is slightly increased, with a higher bromine ratio. Additionally, the radiant efficiency shows weak dependence on the discharge gap.