Optical fibre-fed radio system configurations

Demand for broadband services is expected to increase dramatically over the next decade. Optical fibre and millimetre-wave radio are both capable of supporting the large bandwidth requirements associated with these services. Millimetre-wave radio systems, operating at the 60 GHz region, such as the RACE Mobile Broadband System or radio LANs, are flexible and offer the advantage of expedient provision. It is likely, therefore, that a hybrid network comprising both radio and fibre will play a significant role in broadband local-access systems. One of the principal advantages of the fibre-fed radio technology is the freedom to concentrate some of the remote equipment at a central site, where these factors are more easily controlled. Expensive equipment can be shared among a number of radio nodes, resulting in a reduced complexity at the radio node. This paper suggests a new configuration for the integration of millimetre wave and optoelectronic devices, and describes the design of a diplexer-antenna unit suitable for the remote site of a fibre-fed radio system. Also it gives experimental results on optical injection locking of mutually coupled patch antenna oscillators, designed for such radio nodes.