Communication Systems at Millimeter Waves

The technical advantages of mm-waves for short range and high data rate radio communications are well known: The availability of bandwidth, the robustness against interception and jamming, and the possibility of repeated frequence reuse after considerably small distances given by a high basic path attenuation and by certain propagation limits of atmosphere. Otherwise some unsolved problems are existing, which hinder a broad application up today. These are: considerable high costs for mm-wave components even for monolothic GaAs-devices have to be considered; no expectations for replacing GUNN-and/or IMPAlT-diodes by three-pole devices are visible for the near future; no simple and lowcost coding/modulation-technique is available for handling intersymbol-interference at high data rates; lack of simple, fast and flexible frequency assignment procedures impede the acception of existing mm-wave communication equipment by possible customers. In the first part the paper will show, which attempts are made for attacking these unsolved problems. The second part gives an overview about realized and potentially new system implementations in the frequency range from about 30 to 60 GHz. Examples are: point-to-point radio links at 38 GHz as LAN-extensions for transmission ranges up to about 4 km; mobile radio links at 38 GHz for track-guided vehicles, e.g.. trains, monorails, and maglevs; radio LAN's at 60 GHz within buildings; and road traffic information systems at 60 GHz.