Radar Distance Measurements in Over-sized Circular Waveguides

One of the main tasks of industrial radar systems is the determination of distances to a reflecting object. An important application is the measurement in metal tubes e.g. by means of the FMCW method. A comparison of measurements in metal tubes and in free-space shows that several problems arise due to the non-perfect coupling between the feeding antenna and the metal tube. This contribution describes the problems caused by dispersions and multi-mode propagations, and presents approaches for their solution