Unexpected measurement results of 94 GHz lens antenna in short far-field conditions

A hyperbolic W-band lens antenna has been designed to study the measurement limitations of a far-field range at short far-field conditions in LEAT, University of Nice, France. A reference measurement is performed at 94 GHz in a planar near-field range at TKK, Helsinki University of Technology, Finland. Near-field measurement accuracy is calculated and the measurement results of the different ranges are analysed. It turns out that unrealistically good results can be obtained if a defocused antenna is measured in short far-field conditions.