The negative electrostatic field created by the grid in the vicinity of the cathode would inhibit the passage of emitted electrons and reduce the current to the plate. Thus, a few volt difference at the grid would make a large change in the plate current and could lead to a much larger voltage change at the plate; the result was voltage and power amplification. In 1908, De Forest was granted a patent () for such a three-electrode version of his original Audion for use as an electronic amplifier in radio communications. This eventually became known as the triode.