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Near-Field to Far-Field Transformation and Fault Detection Using Adaptive Sampling and Machine Learning in Source Reconstruction Method
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- Author / Creator
- Rezvan Rafiee Alavi
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Until not so long ago, near-field and far-field measurement techniques were the two prominent approaches to evaluating antennas. A direct far-field measurement can be conducted in outdoor or indoor environments. The measurement of small antennas can be performed in anechoic chambers. For large antennas, however, a remote open-air-test-site which consists of a large domain in a rural area is required to stay away from reflections \cite{b1}. In near-field techniques, antenna emissions are measured in the radiating near-field region. The near-field data are then projected to the far-field using well-established and trustworthy algorithms. Recently, these methods have been used widely since they allow the accurate measurement of antennas in a controlled environment \cite{b2}-\cite{b10}. The assessment of antenna design using the aforementioned techniques is expensive and time-consuming for antenna designers and wireless engineers, especially those who want to do fast-prototyping and investigate the effect of different parameters in their design.
Time-to-market and project costs are two fundamental considerations which have an indisputable effect on Printed circuit board (PCB) and antenna designers' success in developing their products. The near-field data give RF (Radio Frequency) and antenna engineers a unique insight into the main problems which cause design failure. A fast high-resolution electromagnetic compatibility (EMC) and electromagnetic interference (EMI) testing enable PCB designers to detect and root out unintended emissions and get the approval for compliance tests in real-time. The purpose of this study is to increase the accuracy of the near-field-to-far-field-transformation (NFFF) and fault detection algorithms and current-reconstruction methods while keeping the speed of the proposed technique suitable for real-time applications.
The near-field measurements are performed using RFX2 that is a bench-top very-near-field measurement tool. RFX2 is a planar array of electronic probes which measure the magnetic field in two orthogonal directions. Then the data are projected into the far-field using plane wave spectrum (PWS) transformation. The developed algorithms result in better accuracy and speed for RFX2 and can be applied to other near-field measurement systems as well.
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- Graduation date
- Fall 2019
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
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