Dual Purpose Antenna for Hybrid Free Space Optics/RF Communication Systems

The concept of hybrid free space optical/radio frequency (FSO/RF) communications has been considered for the last mile access network applications. The existing schemes mostly use two separate transceiver antennas for outdoor terrestrial links of few kilometres long. In this paper, we propose and investigate a single hybrid FSO/RF antenna that could be used in high-speed access networks. We outline the design procedures based on the concept of Cassegrain antenna, and show how the FSO transceiver is incorporated into the original design. The proposed antenna is fabricated and extensive measurements are carried out for the radiation pattern, return loss, RF signal-to-noise ratio and the FSO received power. By performing link budget analysis and the results obtained from experiments, we demonstrate the operation of proposed hybrid antenna with 1 × 3 single-input multiple-output configuration and an equal gain combining at the receiver under moderate regime turbulence regime.