We observe enhanced terahertz (THz) radiation generated from a Si3N4 film-coated GaAs photoconductive dipole antenna. Compared to an uncoated antenna with identical electrode geometry and optical excitation power, the Si3N4 film-coated antenna has a higher effective DC resistance and larger breakdown voltage. As a result, the peak amplitude of generated THz radiation is significantly enhanced due to the Si3N4 film-coated layer. Compared to an uncoated antenna with identical electrode geometry and optical excitation power, the Si3N4 film-coated antenna has a higher effective DC resistance and larger breakdown voltage . As a result, the peak amplitude of generated THz radiation is significantly enhanced due to the Si3N4 film-coated layer.