A New Advanced MM-Wave Test Facility for EM Field Measuring of Large Antenna Systems up to 200 GHz

The measurement of the characteristic antenna data by means of conventional far-field test ranges in frequencies around 200GHz requires measurement distances of up to some kilometers. The high atmospherical attenuation and the low available transmit power limit the dynamic range of the measurements considerably. Advanced measurement techniques like the so-called CATR (Compact Antenna Test Range) avoid these disadvantages and allow measurements with a considerably higher accuracy. The high precision test facility developed by and installed at MBB has got a quiet zone of 5.5 × 5.0 × 6.0 m. This new measurement concept is quasi-optical and consists of two doubly curved reflectors which generate a coherent electromagnetic field (quiet zone) from a spherical wave. The reflectors are placed and curved so as to prevent inherent cross-polarization and to create very high constant amplitude and phase in the quiet zone. The precision reflectors have an extremely exact surface accuracy and thus allow their use even in the millimeter wave range. For the maximum operational frequency band of about 200GHz, the relative roughness is in order of lambda/60. This results in considerably lower degradati on for this type of measurement range compared to the typical degradation on far-field ranges (lambda/16). The specific features and applications of this type of facility will be explained and presented in detail. Furthermore, qualification results will be presented for the frequency ranges of 60, 180 and 2006Hz.