Optically-Fed 5GHz Patch Antennas Excited by Vertical-Cavity Surface-Emitting Lasers

This paper describes a compact and low cost optically fed antenna for using as a receiver in 5G cellular networks and in distributed antenna systems. It compares the performance of two different topologies of patch antennas tightly integrated with vertical-cavity surface-emitting lasers (VCSELs), without the need for an amplifier stage or matching circuit. Opto-microwave (OM) gain of −21.5 dB at 5.15 GHz for the Microstrip patch antenna (MPA), and −24.2 dB at 4.8 GHz for the Grounded Coplanar patch antenna (GCPA) are achieved. The MPA architecture is quite original as it removes the need for RF feed lines through a direct injection of the signal from the patch to the VCSEL. The paper evaluates the different contributions to the total gain due to the VCSEL responsivity, the coupling between the optical fiber and the VCSEL, the wire-bonding losses and the antenna gain, with the goal of optimizing the steps at which major losses occur.