A back Faraday shield is proposed for improving a cooling design of Faraday shield and better antenna-plasma coupling of a fast wave antenna. The radiofrequency properties of an antenna with the back Faraday shield have been investigated in the JFT-2M tokamak. The loading resistance of the antenna was significantly higher than that of an antenna using a conventional Faraday shield. The back Faraday shield antenna did not show adverse results for launching fast waves up to 550 kW of coupled power. The electron heating was observed by a soft X ray spectrum measurement increased by 0.35 keV during 250 kW of fast wave application.