Spherical mm-Wave/THz Antenna Measurement System
This paper presents an automatic characterization system for mm-wave antennas based on aspherical positioning system. It features network-analysis based far-field- andS-parameter measurement ofprobe- and waveguide-fed antennas between 220 GHz and 330 GHz, expandable down to 75 GHz. In eithercase, the antenna under test (AUT) is fixed in the center of a spherical coordinate system and fed by anappropriate feeding structure, whereas the receiving antenna is moved along the surface of a hemisphere.Since the movement of the receiving antenna is inherently limited to constant radii, the measurementof amplitude and phase far-field-pattern is possible in principle. Additionally to the measurement resultsof an open-ended waveguide as AUT, this paper describes two methods for the self-characterizationof possible systematic and stochastic measurement uncertainties. On one hand, repetitive measurementsalong a constant trace are carried out to obtain information about the stochastic uncertainty of far-fieldmeasurements. On the other hand, a synthetic aperture radar (SAR)-approach is used to characterize possibleunwanted reflections within the measurement setup. Finally, the insight obtained from both antenna mea-surements and self-characterization is concluded into performance parameters of the presented measurement approach.