Millimetre-wave antenna and propagation studies for indoor wireless LANs

The combination of increased portability and increased computing power is placing new demands on interconnects with other such new computer systems and existing networks. One possible way of providing the required interconnections while maintaining portability is through wireless systems. Relatively low bit-rate systems are already available in the market place, and faster, second-generation systems are under development. This paper outlines work in progress at CSIRO on millimetre-wave antennas and propagation relating to wireless local area network (WLAN) systems operating at frequencies in the 40 to 60 GHz band for intra-office communication. The basic arrangement for such systems involves a hub antenna, located possibly in the ceiling, and a number of roamable antennas located on desks throughout the room, within a radius of about 20m of the hub. Signals transmitted to and from the antennas are subject to considerable multi-path interference and, whilst this can limit the system performance, it can be used to overcome the effect of obstructions in the direct path. It is apparent that to optimize WLAN performance it is important to understand propagation effects in rooms and to develop antennas whose characteristics match the overall requirements, including cost.<>