Andriy Radchenko

Estimating the radiated emissions from cables attached to a switching power supply in a MIL-STD 461 test

Common-mode currents on cables attached to a switching power supply generate radiated emissions which may interfere with near-by components. A relatively simple equivalent circuit model is developed to predict the radiated emissions measured in a MIL-STD-461 or RTCA/DO-160 test. The intent of this model is to provide an estimate of emissions that allows the designer to better understand the mechanisms behind emissions issues and to rapidly predict the impact of changes to the system, like adding filtering, changing components, or modifying cable connections. The model represents cables connected to the power supply as transmission lines, represents coupling from the cables to the antenna using lumped capacitors, and represents the balun in the antenna using a transformer. The simulated results match the measured results well. This simple SPICE model allows EMI issues to be investigated early in the design of switched mode power supplies.

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.

Transfer Function Method for Predicting the Emissions in a CISPR-25 Test-Setup

The CISPR-25 standard is used in the automotive industry to characterize the electromagnetic radiation of electronic components. The setup is comprised of an electronic device, a cable harness, a metallic table, and an antenna. Dimensions stretch from a couple of meters for the setup to fractions of a millimeter for printed circuit board features. Numerical prediction of radiated emissions (RE) is of great usefulness for prediction of potential electromagnetic compatibility nonconformities in the early design process, but extremely difficult to be done for this setup as a whole. In this paper, we demonstrate how RE can efficiently be computed based on a setup as commonly used to model conducted emissions only, i.e., electric control unit and harness on infinite-ground plane. Applying Huygens principle and using it to generate a fixed transfer function between a particularly chosen Huygens surface and the antenna, we arrive at a novel computing scheme for RE. The scheme is applied for the antenna model and antenna factor-based calculations and demonstrates agreement with measurements within 5 dB range.

Investigation of interference in a mobile phone from a DC-to-DC converter

Turning on the LCD screen of a mobile phone causes desensitization of its receiver in the GSM lower frequency band (900 MHz). In this paper, the measurement techniques used for the investigation of intra-system interference in a mobile phone caused due to the DC-DC converters present on-chip the LCD driver IC are presented. An equivalent noise source model is created by modelling the flexible printed circuit board traces and obtaining a Thevenin equivalent noise by changing the load conditions.

FDTD modeling of absorbing materials for EMI applications

A few scenarios of applying different magneto-dielectric absorbing sheet materials to mitigate electromagnetic inference (EMI) are analyzed in this paper using a full-wave 3D finite-difference time-domain (FDTD) technique. Frequency characteristics of both permittivity and permeability of these magneto-dielectric materials are approximated by the series of the Debye terms suitable for time-domain simulations. This approximation is accomplished using a new curve fitting technique based on the Legendre polynomials and the regression analysis optimization. The results of the numerical simulations are verified by the corresponding experiments, and the good agreement is obtained.

Prediction of Radiated Emissions From Cables Over a Metal Plane Using a SPICE Model

A method for creating a simple SPICE model is proposed such that the SPICE model allows prediction of radiated emissions in component level tests, such as those specified by CISPR 25 and MIL-STD 461. The model predicts measured emissions when the antenna is in the vertical direction, where emissions are typically worst for such geometry. It is shown that the radiation from the ground connections between the cables and return plane dominates over the radiation from the horizontal cables. The currents in these ground connections are predicted by treating the cables above the return plane as transmission lines and by treating the ground connections as infinitesimal radiating dipoles. The electric fields generated by these infinitesimal dipoles are summed at the antenna, where the antenna factor is then used to predict the received voltage at the antenna. Test results show that this SPICE model is able to predict peak emissions within a few dB over a range from 60 MHz up to 1 GHz for a variety of circuit configurations. This model should help circuit designers to better evaluate the design of their components early in the design process and help them to better understand the mechanisms behind emissions problems.

Simulation of automotive EMC emission test procedures based on cable bundle measurements

Two time efficient simulation methods for the prediction of the conducted and radiated automotive EMC emission tests, respectively, are presented. To verify the correct prediction of the cable bundle model, a novel cable bundle test bench has been developed. It allows a fully automated network analysis with up to 32 ports. Several types of cable bundles are experimentally characterized under stochastic considerations. The system simulation for the conducted emission setup is partitioned into four parts connected on circuit level. The statistically analyzed voltage at the output of the line impedance stabilization network is in very good agreement to respective measurements. To simulate the radiated emission a novel method is presented, where the setup is partitioned by the use of Huygens principle. The simulated prediction of the antenna voltage is in good agreement with respective measurements. The presented approaches are very time efficient and therefore can be used effectively during product development.

On different methods to combine cable information into near-field data for far-field estimation

Near-field scanning is often used to solve EMC problems. Aside from the purpose of visualization of near-fields, measured near-field data can be used to estimate far-field. One of many challenges associated with using near-field to far-field transform (NFFFT) technique for EMC application is the handling of attached cables. The objective of this investigation is to evaluate different methods to add cable information to the near-field data for far-field estimation. The investigation is carried out using numerical experiments in EMCoS EMC studio, which is a commercial MoM (Method of Moment) tool for EM simulation. Measurement results from a test structure are also presented to validate the simulation results.

Sheet absorbing material modeling and application for enclosures

This paper demonstrates relevant physics and provides recommendations regarding thin sheet absorber material applications in enclosures of electronic circuitry. Sheet absorbers placed on the walls of an enclosure are studied herein both experimentally and through the full-wave numerical simulations. In practical applications, the applied absorbing patches need to be selected in terms of proper material type, thickness, size, and placement within an enclosure. The goal is to achieve the maximum effectiveness to suppress electromagnetic field at problem resonances in the enclosure.

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.