Millimeter-wave and sub-millimeter-wave radio-over-fiber (RoF) technology with digital-signal-processingÂ? aided coherent detection can be a promising candidate for high-speed radio transmission links with a capacity of greater than 10 Gb/s if the energy consumption does not increase drastically. We demonstrate 100-GHzÂ? and 300-GHz-band simultaneous RoF signal generation using an optical frequency comb source comprising an optical frequency shifter in an amplified optical fiber loop, and its radio transmission over the air. 10-Gbaud quadrature-phase-shift-keying provides a capacity of 18.6 Gb /s with a 7% forward error correction overhead in single carrier signal transmission as well as in multi-carrier transmission.