  We provide an experimental demonstration of a direct fiber-optic link for RF
transmission ("radio-over-fiber") using a sensitive optical antenna based on a
rubidium vapor cell. The scheme relies on measuring the transmission of laser
light at an electromagnetically-induced transparency resonance that involves
highly-excited Rydberg states. By dressing pairs of Rydberg states using
microwave fields that act as local oscillators, we encoded RF signals in the
optical frequency domain. The light carrying the information is linked via a
virtually lossless optical fiber to a photodetector where the signal is
retrieved. We demonstrate a signal bandwidth in excess of 1 MHz limited by the
available coupling laser power and optical density. Our sensitive, non-metallic
and readily scalable optical antenna for microwaves allows extremely low-levels
of optical power ($\sim 1\, \mu$W) throughput in the fiber-optic link. It
offers a promising future platform for emerging wireless network
infrastructures.
