To phase or not to phase in planar near field measurements: Overcoming large probe positioning error

The introduction of phaseless techniques in antenna near-field measurement techniques has revived this field by the promise of operation in higher frequencies. Stepping forward toward the measurements in millimeter frequencies and beyond is highly obviated by the high cost or unavailability of vector instruments. The phaseless methods can provide practical approaches for the antenna measurement requirements at these high frequencies. Apart from the appealing cost effectiveness and practicality at higher frequencies the robustness of these methods against certain planar near-field errors is also demonstrated. The probe-positioning error is an important type of error which can severely affect the extracted far-field patterns of antennas measured over planar near-field facilities. It is the purpose of this paper to study this type of error using both a conventional amplitude- phase and phaseless planar near-field technique. Although this effect is previously examined by simulations but to the best of the authors knowledge it is for the first time that the effect of this error has been measured in an extreme condition through measurements. Both simulation and measurement results correspond to the extremely high level of this specific error to prove the concept. Errors in the order of the frequency of operation wavelength are studied by simulating different type of antennas. A novel approach is also implemented to explore the effect of this type of error in a real measurement environment. The measurements are taken using the UCLA bi-polar near- field facility to assess all the predicted results.