Emission source microscopy for electromagnetic interference source localization

For complex and large systems with multiple sources, it is often difficult to localize the sources of radiation. Near-field electromagnetic scanning is used often for root-cause diagnosis by determining field distribution close to the PCB. In the near-field, the evanescent waves are dominant, which may lead to the misinterpretation of them being the dominant sources contributing to the far-field. Another limitation of near-field scanning is that the probe may not be able to access all locations near the PCB due to the complex geometry and high component density. Two-dimensional synthetic aperture radar is a well-known technique used for antenna diagnostic and alignment of phase array antennas. Using a technique which is derived from the synthetic aperture radar we present emission source microscopy to localize the sources of active radiation on a PCB. After obtaining the location of sources, using near field to far-field transformation, it is shown that the far-field radiation patterns and the total radiated power can be estimated. Using masking algorithms the contribution of individual sources to far-field can be determined. The source localization methodology is presented along with simulation and measurement results on real-DUTs. The results show that the proposed method is capable of detecting multiple active sources on a complex PCB. Different phase measurement methods are presented along with the measurement results. Also, methods to reduce the scanning time for source localization are presented --Abstract, page iii

Real Time Bridge Scour Monitoring with Magneto-Inductive Field Coupling

Scour was responsible for most of the U.S. bridges that collapsed during the past 40 years. The maximum scour depth is the most critical parameter in bridge design and maintenance. Due to scouring and refilling of river-bed deposits, existing technologies face a challenge in measuring the maximum scour depth during a strong flood. In this study, a new methodology is proposed for real time scour monitoring of bridges. Smart Rocks with embedded electronics are deployed around the foundation of a bridge as field agents. With wireless communications, these sensors can send their position change information to a nearby mobile station. This paper is focused on the design, characterization, and performance validation of active sensors. The active sensors use 3-axis accelerometers/magnetometers with a magneto-inductive communication system. In addition, each sensor includes an ID, a timer, and a battery level indicator. A Smart Rock system enables the monitoring of the most critical scour condition and time by logging and analyzing sliding, rolling, tilting, and heading of the spatially distributed sensors

Measurement Methodology for Field-Coupled Soft Errors Induced by Electrostatic Discharge

High-speed low-power mobile devices are sensitive to electrostatic discharge (ESD)-induced soft errors, such as unwanted reset, lock up, loss of user interface, disturbed displays, etc. ESD can couple via current and fields into the internal cabling, printed circuit board traces but also directly into the integrated circuits (ICs). Many portable devices shield nearly all traces using top and bottom layer ground planes, and they apply effective filters at cable entry points such that direct field coupling to the IC can dominate the system\u27s ESD sensitivity. However, a little information is available on the robustness of ICs against direct ESD transient field coupling. A methodology for determining this robustness was developed and applied to a set of consumer electronic ICs to create an initial robustness database. Custom-made electric and magnetic field probes are driven by a 400-ps rise time transmission line pulser to evaluate 37 different ICs. The investigation showed that 50% of the ICs were disturbed at approximately 33 kV/m for the electric field injection and 142 A/m for the magnetic field injection at this rise time. This methodology can serve as the basis for further investigations of ICs. The database can be used to estimate the likelihood of field-coupled ESD-induced soft errors in electronic products

The Development of an EM-Field Probing System for Manual Near-Field Scanning

This research was conducted to visualize the frequency-dependent electromagnetic field distribution for electromagnetic compatibility (EMC) applications and the time evolution of the current flow induced by an electrostatic discharge (ESD) on complex-shaped electronic systems. These objectives were achieved by combining magnetic field probing with a system that automatically records the probe\u27s position and orientation. The local magnetic field associated with the probe location was recorded and displayed at near real time on the captured 3-D geometry. Consequently, a field strength map was obtained for EMC applications. Also, a video showing the spreading of the ESD-induced current with subnanosecond resolution was captured for ESD applications after the ESD-induced surface current density associated with the probe location was recorded

Optical Tracking Based EM-Field Probing System for EMC Near Field Manual Scanning

This paper introduces a method to visualize the frequency dependent electromagnetic field distribution on complex shaped electronic systems. This is achieved by combining magnetic field probing with an optical tracking system for automatically recording the probe position and orientation. Due to the complexity of the shape of the electronic systems of interest, and for utilizing the expertise of the user, the probe will be moved by manually instead of robotically. With the location from the optical tracking system, 3D near field strength map can be obtained at real time during near field manual scanning

EM Radiation Estimation using an Automatic Probe Position Recording System Coupled to Hand Scanning

Compared to scanning by hand, traditional robotic scanning to measure or to inject EM near field has advantages and disadvantages. It can scan large area with excellent resolution. However, it is difficult to program the experience of engineers into the robotic system for selecting scan areas, and complex shaped objects are nearly impossible to scan automatically. A CMM (Coordinate Measuring Machine) arm based probe recording system has been developed to add position recording to hand scanning. Applications of the system include documentation, visualization of the field and current distribution

Coupling Path Visualization using a Movable Scatterer

Suppressing the coupling path between aggressors and victims is always a major issue in EMC design. However, it would be difficult to identify it. In this paper the coupling paths between two monopole antennas were identified using a movable scatterer. By post processing the data, the coupling paths could be visualized as surface plots

Emission Source Microscopy Technique for EMI Source Localization

For large, complex systems with multiple sources at the same frequency, localizing the sources of radiation often proves difficult. This paper presents an emission source microscopy (ESM) technique derived from synthetic aperture radar (SAR) to localize radiating sources on a PCB. Near-field scanning provides limited information about the components contributing to far-field radiation. This paper presents the source localization methodology, supported by simulation and measurement results. After localizing the sources, the far-field contribution and the total radiated power from each individual source can be estimated. The results show that the proposed method can distinguish between multiple radiating sources on a complex PCB