Phaseless measurement techniques

Nicolas Ribière-Tharaud

During the last years, Near-Field techniques have been submitted to a lot of improvements leading to greater accuracy and to faster measurements allowing thus lower costs. The use of probe arrays is a relevant illustration. Phaseless measurements appear as a really challenging issue in order to assess non-controlled sources or in order to get simplified test instrumentation. At Supelec, the Electromagnetism Department is involved for years in near field techniques, including standard antenna measurements, EMC testing or RF dosimetry. Two programs are currently conducted in the domain of phaseless techniques. On one hand, a software based solution has been developed in order to characterize high power microwaves sources using amplitude-only Near-Field data collected on planar surfaces by means of IR radiometry. On the other hand, a hardware based solution (Phase Retrieval Network) has been validated and applied to GSM mobile phones in view of fast SAR assessments. These two approaches and their applications are presented, while advantages and drawbacks are outlined.