Phaseless Inversion of Planar Magnetic Near-Field Antenna Measurements

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EMSCAN, located in Calgary, is a world-leading developer of fast planar near-field antenna and electromagnetic compatibility measurement techniques. This project revolves around the EMSCAN's RFxpert system that provides almost real-time antenna measurements. The RFxpert collects the tangential magnetic fields of an antenna under test (AUT) on a plane in the near-field zone of the AUT. The RFxpert system is capable of collecting the amplitude and phase of these magnetic fields. From these measurements, the radiation pattern of the AUT can be calculated using the standard planar near-field to far-field transformation. EMSCAN is interested in investigating methods to calculate radiation patterns from amplitude-only (phaseless) magnetic near-field data. This is important for the following two reasons. First, this can significantly reduce the cost of the system as phaseless measurements can be simply/accurately done via the use of a power meter/embedded spectrum analyzer. Second, this enables EMSCAN to estimate electromagnetic emissions in their EMC product, EMxpert, that uses only a spectrum analyzer to measure phaseless magnetic near-field data. In the proposed project, the Mojabi team aims to implement a computer algorithm that takes the phaseless magnetic near-field data collected on a plane in front of the AUT, and then returns the radiation pattern of the AUT. To this end, this problem is formulated as the minimization of a nonlinear cost functional over the equivalent current of the AUT. Once equivalent current of the AUT is found, the radiation pattern of the antenna can be easily calculated. The radiation pattern obtained from phaseless magnetic near-field data will then be compared with the radiation pattern obtained from amplitude and phase magnetic near-field data to evaluate how much accuracy has been sacrificed by using phaseless data.