A Ultrawide-Band VCSEL-Based Radar-Over-Fiber System

In this paper, an ultrawide-band (UWB) low-cost Radar-over-Fiber (RaoF) system is presented which exploits optical links based on directly modulated-VCSELs for radio frequency signal distribution from/to the base station to/from the transmitter/receiver front-end. The system, which includes packaging and engineering of the remote transmitter and receiver assemblies, has been tested in a controlled indoor environment using inexpensive patch antennas. Experimental results demonstrate that uncooled VCSELs allow direct modulation through 3 GHz-bandwidth UWB signals with carrier frequency of 7.5 GHz. The demonstrated system guarantees a power budget of 116 dB with a dynamic range of 66 dB, including signal pre-emphasis for in-band equalization compensating for the frequency response of both the packaged VCSEL-on-PCB and the patch antennas gain. The obtained results demonstrate the feasibility of such a low-cost solution for any scenario where remoting of transmitter and receiver up to a few kilometers is desirable together with a high resolution measured to be as accurate as 6.5 cm.