Radiated Emission Measurements Research Articles

TEM-камера открытого исполнения для испытаний малогабаритных радиоэлектронных средств на электромагнитную совместимость

This paper presents the design and fabrication of an open TEM cell. It allows you to measure the radiated emission and immunity of radioelectronic devices. The size of the EUT should not exceed 184×162×30 mm. Performed analytical and quasi-static analysis of the regular part of the TEM cell. In the frequency range up to 1.4 GHz the reflection coefficient |S11| of the regular part does not exceed minus 45 dB. The electrodynamic model of the TEM cell is developed and the geometric parameters are optimized using a genetic algorithm. Analysis of the electrodynamic model showed that in the frequency range up to 920 MHz the voltage standing wave ratio (VSWR) does not exceed 1.3. The inequality of the electric field in the area of EUT placement is not more than 6 dB in the frequency range up to 875 MHz. The validity of the obtained results is checked using the numerical methods of finite elements and the transmission line matrix. A solid-state model of the TEM cell is developed to evaluate the effect of the design features of the assembly. The frequency dependences of |S11| of the solid‑state model do not exceed minus 17.69 dB in the frequency range up to 916 MHz. The TEM cell is fabricated by laser cutting and bending aluminum sheet metal. Using a vector circuit analyzer Micran R4M-18 measured S‑parameters of the fabricated TEM cell. The transmission coefficient |S21| of the fabricated TEM cell in the frequency range up to 936 MHz does not exceed minus 2.2 dB. The reflection coefficient |S11| does not exceed minus 17.69 dB. The results of radiated emission measurements of the Altera Cyclone IV FPGA debug board in the frequency range up to 1 GHz with a fabricated TEM cell is presented.

Field Deviation in Radiated Emission Measurement in Anechoic Chamber for Frequencies up to 60 GHz and Deep Learning-Based Correction

The measurement of radiated emission (RE) in an anechoic chamber becomes very challenging at high frequencies, up to 60 GHz, because the scanning plane of the receiver is in measurement standard deviation from the actual wavefront. As a result, the RE intensity of the devices may be underestimated, resulting in electromagnetic interference. The deviation between the electric field at the far-field vertical scanning point and the actual wavefront is researched. Then, in an anechoic chamber, a hybrid deep learning amendment model of convolutional neural network (CNN) and transformer is proposed to correct the RE measurement at a 3 m distance. The results indicate that the correction is reliable, with an average error of 6.35% for a 3 m distance in a semianechoic chamber and less than 4.83% for other test scenarios. The proposed method provides a promising solution for RE measurement at a millimeter wave band in an anechoic chamber.

Data Processing Mechanism and Algorithm Optimization for Radiated Emission Measurement of Electronic and Electrical Equipment

Radiated emission is one of the most important measurement items in the field of electromagnetic compatibility. The measured value of field strength often deviates from the real value to a certain extent. According to the characteristics of typical log-periodic dipole array antenna, the relation between antenna resonance unit and frequency, as well as the position relation between phase center and calibration reference point, the calculation formula of field strength correction factor is derived. The correction factor of field strength in the 30MHz-1GHz is also calculated precisely. The data processing mechanism of radiated emission measurement is clarified. An optimization algorithm for the measurement of radiated emission is obtained eventually. After the test value is optimized by the correction factor, more accurate field strength can be obtained. The optimization interval is within (-0.348, 2.741) dB. As a data processing mechanism of the radiated disturbance, it can not only improve the accuracy of measurement, but also reduce the uncertainty and error.

Interlaboratory comparison of radiated emission measurements using a tubular dipole

This paper presents an interlaboratory comparison of radiated emission measurements in the frequency range of 30-1000 MHz. A tubular dipole was specifically designed and employed as a reference emitting source. The most important for a tubular dipole is stability in the testing process. The stability is not the performance of the sample, but the emission signal of the sample is stable. In addition, two ways of determining the reference value of the electromagnetic field strength are considered. The first reference value is obtained by using robust analysis. It is a robust average value that is calculated by averaging the measurement results provided by the participating testing laboratories. The other reference value is obtained through the simulation-experimental results of the tubular dipole in the semi-anechoic chamber or full anechoic chamber, for horizontal and vertical polarizations and 3 m distance measurement, respectively. In addition, this value is assigned by the coordinator. Measurement results are compared using the robust z-scores and -scores, respectively.

Practical Papers, Articles and Application Notes

Inter Laboratory Comparison (ILC) forms an integral part of an EMC test laboratory competence level. It provides objective evidence for accreditation purposes as well as demonstrates the comparability and acceptability of the test results measured in the accredited laboratory. The first paper, “Importance of Performance Improvement for Inter Laboratory Comparison (ILC) of Radiated Emission Measurements,” reveals that the test conditions and methodologies of the laboratories cannot be totally identical when testing a sample based on ILC. This can cause deviation in radiated emission (RE) measurement results, in addition to those described sources of uncertainty in the standards. Based on the test results obtained from 16 EMC test laboratories participating in the ILC program, the factors influencing the ILC program, performance improvement techniques, and corrective measures are discussed.

Importance of Performance Improvement for Inter Laboratory Comparison (ILC) of Radiated Emission Measurements

The key factors that influence the Radiated Emission (RE) measurement results of Inter Laboratory Comparison (ILC) program, conducted as part of proficiency testing/Quality Assurance of EMC test laboratory are presented in this paper. The evaluated classical Z score results and overall performance of the participant EMC test laboratories in ILC program are affected by these factors. The performance improvement techniques to address the influencing factors and eliminate the deviation in test results of ILC program are outlined in detail. A case study was conducted in the frequency range from 30 MHz to 1 GHz, as the deviation in Z score results is predominant below 1 GHz. The importance of awareness required to conduct ILC program accurately with minimum possible errors is highlighted in this paper.

An Analytical Approach for the Estimation of the Far-Field Reduction Obtained by Placing Closed Conductor Loops in Proximity to a Chip

A recent study proposed a technique to mitigate the far-field emission and susceptibility of printed circuit boards (PCBs) with the use of a suspended metal loop. This article provides, with the help of the small-loop theory, a methodology to analytically predict and further estimate the electromagnetic field (EMF) distribution and level at very large distances from the emitting PCB (as is the case for CISPR radiated emission measurements up to 10 m test distances), where full-wave simulations and experiments are very challenging (if not impossible as a practical matter). The suitability of the methodology was assessed for various radiator size and frequency as well as the loop radius and configuration with respect to the emitting PCB. As proof-of-concept, full-wave simulations and measurements have been performed. The root-mean-squared error (RMSE) was considered as the measure of the accuracy between the analytical and full-wave numerical results. It has been demonstrated that, whatever the loop radius and/or position with respect to the radiating integrated circuit (IC), the proposed methodology can approximate the far-field EMFs with low RMSE values. Moreover, as far as the emitting IC is concerned, independently of its size and radiating frequency (except near the loop resonance), a good precision was achieved with the analytical model compared to the full-wave numerical analysis. Furthermore, the approach was found to be effective not only on-axis but also off-axis of the suspended conductor loop. Apart from the required computational power for full-wave simulations, thanks to the proposed methodology, it is possible to significantly reduce the huge difference in computational time for numerical ( $\gg$ 30 min, depending on the distance) and analytical ( $ few seconds, independently of distance) analyses.

A Compact, Broadband, and Calculable Electromagnetic Field Source for Quality Assurance in EMC Testing

The aim of this article is to describe the design, realization, and characterization of a compact, broadband, and calculable electromagnetic field source. The source has been extensively used as a traveling reference radiator in proficiency tests of radiated emission measurements. The result of its characterization has been validated by more than 500 measurements over the frequency range from 50 to 6000 MHz in semianechoic (3 and 10 m) and fully anechoic (3 m) chambers. The use of the source as a reference radiator for emission measurements could be extended to other testing facilities, such as transverse electromagnetic waveguides and reverberation chambers.

Low-cost Transverse Electromagnetic (TEM) cell design for radiated emission measurement

The increasing use of electronic and electrical equipment that continuously emits radiated emissions in the industrial, military, communications, household, and medical fields has increased dramatically over the past few decades. Radiated emission can interfere performance of other electronic devices around it. There is a demand for electric devices to comply with electromagnetic compatibility (EMC) standards before being marketed, requiring manufacturers to carry out EMC testing before devices enter the market. Transverse Electromagnetic (TEM) cells are usually used by designers to ensure that electronic devices comply with EMC standards. TEM cells for radiated emission measurement are widely used because they are cheap and time-saving before full compliance testing is carried out, which expensive for one-time screening. The main problems of commercial open TEM cells are relatively high price, weight, handling problems and portability. In this study, low-cost TEM cells were designed that could be used to test radiated emission generated by electronic devices. The fabricated TEM cells can operate up to 960 MHz and it can be used to test radiated emission generated from small electronic devices. It has better performance and more sensitive than branded TEM cells in the radiated emission test of a mobile phone.

Machine learning-assisted soot temperature and volume fraction fields predictions in the ethylene laminar diffusion flames.

Inferring local soot temperature and volume fraction distributions from radiation emission measurements of sooting flames may involve solving nonlinear, ill-posed and high-dimensional problems, which are typically conducted by solving ill-posed problems with big matrices with regularization methods. Due to the high data throughput, they are usually inefficient and tedious. Machine learning approaches allow solving such problems, offering an alternative way to deal with complex and dynamic systems with good flexibility. In this study, we present an original and efficient machine learning approach for retrieving soot temperature and volume fraction fields simultaneously from single-color near-infrared emission measurements of dilute ethylene diffusion flames. The machine learning model gathers information from existing data and builds connections between combustion scalars (soot temperature and volume fraction) and emission measurements of flames. Numerical studies were conducted first to show the feasibility and robustness of the method. The experimental Multi-Layer Perceptron (MLP) neural network model was fostered and validated by the N2 diluted ethylene diffusion flames. Furthermore, the model capability tests were carried out as well for CO2 diluted ethylene diffusion flames. Eventually, the model performance subjected to the Modulated Absorption/Emission (MAE) technique measurement uncertainties were detailed.

Application of Bayesian tomography method to the visible spectroscopic diagnostic on HL-2A tokamak

As the commission of a visible spectroscopic diagnostic to the HL-2A tokamak for the measurements of both bremsstrahlung continuum radiation and impurity line emission, a Bayesian tomography method has been developed to this diagnostic for the reconstruction of a 2D emission distribution from line-integrated data. In this method, Gaussian process prior is adopted as an effective way to regularize the smoothness of the emission field, which can be truncated to enforce non-negative constraint of the emission values. For the reliability and quality assessment, uncertainty of the reconstruction can be examined through its confidence interval derived from a posterior probability. Performance of this Gaussian processtomography method is exemplified by the reconstructions of the bremsstrahlung continuum emission, which coincide with the equilibrium magnetic flux surfaces with respect to position and shape. In another case the reconstruction of CVI line emission in the visible range (n = 8→7, 529.05 nm) disclose the existence of a bright radiation belt due to the plasma–wall interaction.

Towards the Prediction of SpaceWire Radiated Emissions Employing an LVDS Signal Emulator

The majority of the past and current ESA’s, NASA’s, and JAXA’s science missions utilize broadly SpaceWire (SpW) Links, with Low Voltage Differential Signaling (LVDS) for the physical layer, to transfer mission data. Electromagnetic Compatibility (EMC) and Electromagnetic Interference (EMI) problems caused by harnesses’ radiated emissions remain a constant open issue in every mission due to the scientific payload sensitivity. A common cause of radiated emissions from shielded cable bundles can be traced to the currents flowing on the shield of the harness. This work aims to present a complete methodology for predicting the Electric field emissions in the case of an operating SpW link, while it can be expanded to any shielded cable which utilizes LVDS. The physical and protocol layer of the link are implemented via a developed LVDS Signal emulator, handling both the characteristics of the signals at the outputs of the LVDS line drivers and the effects of their transmission across the link along with the termination scheme, in order to calculate the common mode current flowing on the shield. The radiated emissions can then be estimated considering the ground material and a detailed harness topology, employing traveling wave antenna theory. The validity of this approach is assessed by comparing the predictions with actual link radiated emissions measurements. Simulation results are in good agreement with the measurements, rendering this methodology a fast tactic for the pre-compliance procedure for the early design stage of the science space mission.

Kirchhoff’s Thermal Radiation from Lithography-Free Black Metals

Lithography-free black metals composed of a nano-layered stack of materials are attractive not only due to their optical properties but also by virtue of fabrication simplicity and the cost reduction of devices based on such structures. We demonstrate multi-layer black metal layered structures with engineered electromagnetic absorption in the mid-infrared (MIR) wavelength range. Characterization of thin and Si films sandwiched between two Au layers by way of experimental electromagnetic radiation absorption and thermal radiation emission measurements as well as finite difference time domain (FDTD) numerical simulations is presented. Comparison of experimental and simulation data derived optical properties of multi-layer black metals provide guidelines for absorber/emitter structure design and potential applications. In addition, relatively simple lithography-free multi-layer structures are shown to exhibit absorber/emitter performance that is on par with what is reported in the literature for considerably more elaborate nano/micro-scale patterned metasurfaces.

Consideration to Terminating Condition of Mains Cable for Radiated Emission Measurement Caused by Different Disturbance Sources

Very high frequency (VHF)-line impedance stabilization network (VHF-LISN), which is defined as the termination device for mains cable of equipment under test to specify the input impedance of each line at the mains power supply outlet, can improve correlation between test sites that perform radiated emission measurement. Balanced and unbalanced types of VHF-LISN are currently under proposal with International Special Committee on Radio Interference (CISPR) as a device for prescribing the terminating condition of the power supply cable. Simulation analysis with common mode (CM)/differential mode (DM) signal sources was performed to investigate the emission characteristics with the two types of termination devices under several measurement arrangements that used two-wire and three-wire mains cables. Furthermore, to confirm the validity of the simulation analysis, measurement of a versatile comb-generator-operated by ac mains was performed under the same test arrangement and two types of termination devices. Quasi CM/DM signal from an ac-operated comb generator was injected back into the mains cable of the same comb generator. This article explains how we ascertained the radiated emission characteristics with each termination device, and provides guidance for their appropriate usage.

A Novel Approach for On‐Site Measurement of Radiated Emission of EMU

The main problem in on-site radiated emission test of EMU (Electric multiple unit) is the excess ambient electromagnetic noise due to the complex electromagnetic environment. In order to solve this problem, this paper proposed a novel approach for on-site radiated emission measurement test. A joint algorithm comprise blind source separation and adaptive signal processing is used to suppress the ambient electromagnetic noise. The normalized estimation of ambient electromagnetic noise is obtained by blind source separation algorithm, then the normalized estimation of ambient electromagnetic noise is used as the reference signal to adaptively cancel the ambient noise in the mixed electromagnetic noise, so the estimation of radiated noise of EMU is obtained. The simulation and experiment results showed that the proposed method can effectively suppress the ambient electromagnetic noise, thus realize the accurate measurement of the radiated emission of the EMU.

Time‐domain low‐frequency non‐periodic transient EMI measurement system

In this study, a time-domain low-frequency non-periodic transient electromagnetic interference (EMI) measurement system is presented. By the use of an antenna, an anti-aliasing filter, and a digital oscilloscope, the radiated emissions measurement specified by electromagnetic compatibility standard MIL-STD-461 is achieved. In the first stage, the antenna receives the radiated emissions of the device under test and the time domain output voltage is acquired in the oscilloscope. Then, to fulfil the spectrum measurement as accurate as an EMI receiver, a spectrum calculating methodology is carried out. Optimised inverse fast Fourier transform procedure for spectrum estimation in the proposed methodology is implemented to reduce the calculation efforts. The proposed EMI measurement technique required only a single time-domain acquisition and no repeatedly continuous scanning was imposed on the frequency measurement of the EMI test receivers. Due to this benefit, scan times are decreased by several orders of magnitude in comparison with a traditional EMI receiver.

Notice of Retraction: A Compact, Broadband, Calculable Electromagnetic Field Source for Quality Assurance in EMC Testing

The aim of this article is to describe the design, realization, and characterization of a compact, broadband, and calculable electromagnetic field source. The source has been extensively used as a traveling reference radiator in proficiency tests of radiated emission measurements. The result of its characterization has been validated by more than 500 measurements over the frequency range from 50 to 6000 MHz in semianechoic (3 and 10 m) and fully anechoic (3 m) chambers. The use of the source as a reference radiator for emission measurements could be extended to other testing facilities, such as transverse electromagnetic waveguides and reverberation chambers.

Radiated emissions comparison of seven-stage modal filter constructions for Ethernet 100Base-T network protection

The authors consider Ethernet protection devices based on modal filtering. Radiated emission measurement results for three modal filter constructions are presented. It is shown that the improved construction of a non-resistive filter has lower emission levels than the original one.

Accurate Models for Evaluating the Direct Conducted and Radiated Emissions from Integrated Circuits

This paper deals with the electromagnetic compatibility (EMC) issues related to the direct and radiated emissions from a high-speed integrated circuits (ICs). These emissions are evaluated here by means of circuital and electromagnetic models. As for the conducted emission, an equivalent circuit model is derived to describe the IC and the effect of its loads (package, printed circuit board, decaps, etc.), based on the Integrated Circuit Emission Model template (ICEM). As for the radiated emission, an electromagnetic model is proposed, based on the superposition of the fields generated in the far field region by the loop currents flowing into the IC and the package pins. A custom experimental setup is designed for validating the models. Specifically, for the radiated emission measurement, a custom test board is designed and realized, able to highlight the contribution of the direct emission from the IC, usually hidden by the indirect emission coming from the printed circuit board. Measurements of the package currents and of the far-field emitted fields are carried out, providing a satisfactory agreement with the model predictions.

Shielding Effectiveness Simulation of SMT EMI Gaskets Utilizing ANSYS HFSS

Abstract As more components populate smaller board areas, the risk of unwanted coupling between components increases. Shielding and radiated emissions tests outlined by IEEE standards such as IEC 61000-4-21 and ASTM4935D identify measurement techniques to quantify shielding effectiveness. In a PCB topology, shields enclose components to create a Faraday cage, but necessitate a method to ground and fasten the shield to the PCB. Typical methods include the use of gaskets, sealants and clips. This paper reviews a gasket methodology and validates a parameterized ANSYS HFSS simulation with the measured relationship between gasket configuration and shielding effectiveness. Surface mount, rectangular, compressible gaskets manufactured by W.L. Gore & Associates, Inc. are used in several configurations to shield a PCB radiator. Radiated emissions measurements are performed in an ETS-Lindgren reverberation chamber to evaluate shielding effectiveness for each configuration. ANSYS HFSS, a full wave Finite Element Method (FEM) electromagnetic simulation solver, is used to simulate each geometric configuration and is verified with measured results.