Improvements for Near-field Scanners Consisting of Planar Array of H-Field Probes

• Author / Creator

  Ali Kiaee

• Modern wireless applications require flexible and adaptable multi-purpose wireless devices. These devices need to sense environmental conditions, adapt to user requirements, and decide how to communicate among themselves in a self-organized manner. Achieving such versatility and performance along with fast prototyping is extremely difficult, if not impossible utilizing current state-of-the-art measurement techniques. Designing state-of-the-art digital, RF (Radio Frequency) and antenna subsystems that use fast-prototyping with fast measurements is a significant challenge and a potential bottleneck of every modern-day industrial design process. Probe-array based measurement devices have been shown to be novel measurement EMC (Electromagnetic Compatibility)/RF tools [1] which have significantly facilitated the near-field measurement and diagnosis of antennas and PCBs. Probe arrays make it possible to perform certain vital EMC/EMI tests, and antenna measurements, which can be performed inside the lab-environment, in real-time. Real-time methods introduce a huge added-value for industry to diagnose EMC/EMI problems associated with high-speed digital PCBs, which are time varying and can be difficult during long measurement times.Despite all the features array-based measurement tools have to offer, they are new and require a considerable level of further research. In this thesis, it is aimed to help EMSCAN, a corporation that manufactures array-based scanners, enhance the quality and accuracy of their measurement systems, as well as enabling them to reach new markets by developing innovative applications. From the technical point of view, the scanner problem’s setup can be described as follows: There is a planar array of 1600 probes backed by a finite dielectric slab and a copper ground plane. The inputs of the problem are the probe voltages measuring magnetic very near-field of a device under test (i.e. PCB, antenna …). The general desirable outcomes for this thesis are 1) the far-field patterns of the device under test (DUT) for antenna applications and 2) the field reconstruction close to the ones radiated by the DUT for diagnosis, and EMC/EMI applications. This thesis contains 3 main chapters. Chapter 2 deals with ground plane de-embedding in which a novel algorithm is proposed to correct for distortions introduced by the ground plane of the scanner using 4 source reconstruction models (SRM). Chapter 3 assesses existing source reconstruction models that can be used for 6-sided measurements (stitching 6 individual FFs) in terms of their ability to be used for a magnetic scanner. It also proposes a novel algorithm to correct for the dominant source error introduced by this type of measurement system. Chapter 4 shows that dyadic Green’s functions are accurate tools for analyzing planar absorber stacks. It also proposes a Novel technique for post absorber field estimation for EMC/EMI applications.The novel algorithms developed through this thesis are: 1) Ground de-embedding algorithm described in the chapter 2, correction algorithm described in chapter 3 and field estimation algorithm described in chapter 4.Also, this thesis showed that 1) Green’s functions are accurate tools for analyzing planar stack of absorbers (Chapter 4) and 2) previous SRM studies does not necessarily hold for magnetic probe-array based measurements (Chapter 3).

• Subjects / Keywords

  • near-field measurement
  • method of moments
  • computational electromagnetic

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-rn3x-ke58

• License

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