Evaluation of beam switching antennas
Mobile access networks require high performance and high reliability. High performance optically beam formed base station adaptive antennas overcome many of the limitations encountered in fixed wireless access networks. These limitations include restricted coverage and interferences from man made and natural obstacles such as adverse weather conditions. With beam-forming antennas, an antenna algorithm can be set to receive a signal predominantly from a desired direction. The digital processing can shape the radiation pattern for both reception and transmission and can steer beams in the direction of the desired signal, removing interference. These systems need to be tested in order to assure their efficiency. Through the OBANET project and for the first time photonic integrated beamformers based on telecom-market oriented optical chips have been developed and evaluated on a laboratory platform. The computer controlled evaluation platform was developed to characterise beam-forming networks operating above the 35GHz band. It measures the radiation pattern of an antenna and performs data transmission both from ground-to-satellite, (uplink) and from satellite-to-ground, (downlink) directions. The performance of optically beam formed switched beam antennas, which are photonically integrated, has been evaluated and their radiation pattern obtained in both the uplink and downlink directions. The electrical to optical and optical to electrical conversion and the photonic processing of the signal were shown not to increase the signal to noise ratio, therefore usability is not limited. These laboratory-based data are likely to form the foundation for key new developments in the terrestrial and wireless networks industry, aimed at improving performance and overcoming current limitations.
