Sources Of Electromagnetic Emission Research Articles

EMC Research and Design for a Fiber Access Communication System

A fiber access communication system is developed to cater for the need of network communications industry. In this paper, the basic framework of the system is described; with regards to the characteristics of the system, firstly the electromagnetic interference approaches of the whole system are discussed. Emphasis is laid on the engineering analysis and discussion of the interference sources of electromagnetic emission, with solutions thereof suggested; meanwhile, analysis and discussion are conducted on the electromagnetic immunity of the system in view of electromagnetic coupling paths, with corresponding solutions put forward as well. Lastly, the EMC testing results of the system is presented. Practice has proven that this approach is specially favorable for EMC design and comprehension throughout the system development process, which is also effective for the communication industry in EMC design and verification.

Performance analysis of GPU-accelerated filter-based source finding for HI spectral line image data

Searching for sources of electromagnetic emission in spectral-line radio astronomy interferometric data is a computationally intensive process. Parallel programming techniques and High Performance Computing hardware may be used to improve the computational performance of a source finding program. However, it is desirable to further reduce the processing time of source finding in order to decrease the computational resources required for the task. GPU acceleration is a method that may achieve significant increases in performance for some source finding algorithms, particularly for filtering image data. This work considers the application of GPU acceleration to the task of source finding and the techniques used to achieve the best performance, such as memory management. We also examine the changes in performance, where the algorithms that were GPU accelerated achieved a speedup of around 3.2 times the 12 core per node CPU-only performance, while the program as a whole experienced a speedup of 2.0 times.

Computer Platform Adaptive Interference Cancellation Using Higher-Order Statistics

Broadband wireless interference in a computer platform is the result of multiple dynamic electromagnetic emission sources. This interference is non-Gaussian and a receiver design based on the Gaussian assumption will yield suboptimal performance. In fact, it has a double-sided K-distribution and needs to be treated differently in the design process. When dealing with this type of interference in the presence of white Gaussian noise, traditional interference/noise cancellation schemes do not produce satisfactory results. In this paper, we present an interference mitigation method which improves BER performance. We do this by using the cross-cumulant as the criterion of goodness. Specifically, our algorithm is based on higher order statistics (HOS) and is designed to reconstruct and to cancel the interference in a recursive fashion. The algorithm is tested on both BPSK and OFDM communication environments. We compare performance in terms of BER against other cancellation methods.

Electromagnetic Waves from TNT Explosions

Experimental observations indicate that electromagnetic (EM) radiation is emitted after the detonation of high explosives (HE) charges. The movement of ionized atoms, particles and electrons seems to be the underlying cause. Expansion of the detonation products (DP) drives a strong (~1 kb) shock in surrounding air. This forms an intense thermal wave (T ~11,000 K) with duration of ~20 microseconds. Such temperatures create significant ionization of the air. According to Ohm’s Law, movement of ionized patches generates current; and according to the Biot-Savart Law, such currents induce electric and magnetic fields. We investigate these effects through numerical simulations of TNT explosions. A high-order Godunov scheme is used to integrate the one-dimensional conservation laws of gasdynamics. An extremely fine grid (10 microns) was needed to get converged temperature and conductivity profiles. The gasdynamic solution provided a source current, which was fed into a time-domain Green’s function code to predict three-dimensional electromagnetic waves emanating from the TNT explosion. This analysis clearly demonstrates one mechanism—the Boronin current—as the source of EM emissions from TNT explosions, but other mechanisms are also possible.

Filtracja zaburzeń przewodzonych w rezonansowym konwerterze do zasilania lamp z diodami LED dużej mocy

This paper presents design process of one-phase 120W switching mode power supply dedicated for luminaires with LED diodes according to EU standards. Technics of detection of electromagnetic emission sources in the SMPS sub-modules as well as methods of reduction of conducted emission level were shown. Conducted emission filter in resonant converter for high power LED lighting applications.

Research on the Waveform Synthesis of Electromagnetic Detection Inverter Based on FPGA

Complex geological conditions and limited launch frequencies are the problems which the geological electromagnetic detection faced in our country. In this paper, we designed two FPGA-based detection of electromagnetic emission source inverter control circuits, one is using a phase-shift and complementary drive signal to expand the load range of electromagnetic emission system; the other one is using waveform synthesis technology to achieve that multiple frequencies could launch at one-time, and this method improves the detection accuracy. Both the two control circuits have a positive role in promoting the performance of electromagnetic detection equipment the development of Geological Survey in China.

Measurements of Magnetic Field Emission of Various Digital Circuit Layouts

Signal or power to ground traces on a printed circuit board (PCB) of digital products may act as an efficient loop antenna radiating magnetic field when the length is greater than the wavelength of the high frequency current. Employment of proper routing of the return current path, filtering and damping resistor is best practices in the design criteria to minimise sources of electromagnetic emission at PCB level. It is important to indicate that the use of guard traces, filtering at supply network of critical component and damping resistor on signal traces can be the options of emission reduction techniques on double sided assemblies as it will reduce the emission level. In this paper, three double sided test boards are developed to evaluate the impact of the aforementioned mitigation methods on near magnetic field emission. The magnetic field distributions over each layout are measured in order to reveal the profile of radiation to gain further understanding on the net current distribution on the traces of the digital circuit. It is seen that by proper design of return current path, the magnetic field is reduced by average of 16.5 dB.

Measurement of IC-Conducted Emissions by Employing a Backward-Wave Directional Coupler

Semiconductor technology has progressed over the last few years to the point where modern integrated circuits (ICs) have become the main sources of electromagnetic emissions (EMEs) at the electronic system level. As new generations of technology have become accessible, die dimensions and clock frequencies have increased causing ever-larger switching currents to be drawn from the power supply. Interconnections routed at the chip level, bonding wires and package frames act as antennas that cause parasitic radiation (IC radiated emissions) while radio frequency (RF) currents that superimpose the nominal currents (power and signal currents) at the IC ports drive the unintentional emissions of printed circuit board (PCB) traces (IC-conducted emissions). Recognizing the importance of IC EMEs, equipment manufacturers are beginning to require semiconductor companies to specify the IC emission levels. For these reasons, research activities in the field of characterization techniques of ICs in terms of EMEs are receiving increasing attention, and several methods have been proposed to measure the EMC performances of ICs. A new method to measure IC-conducted EMEs using a backward-wave (BW) directional coupler is presented in this paper. The coupler consists of two-coupled microstrip lines employed to measure the spectrum of the current delivered through IC pins with low invasiveness and high repeatability. The operation principle of the method is described and the design criteria for the coupler are given. The results of experimental tests performed using the coupler are compared with those obtained with a standard technique to prove the effectiveness of the method.

Multiscale computer design of photonic crystal based materials for optical chemosensors

A multiscale method is proposed for modeling elements of optical chemosensors based on photonic crystals. The method is based on the first-principles quantum-chemical and electrodynamic calculations. A technique is proposed that takes into account electromagnetic emission sources in the framework of the finite-difference time-domain method. An end-to-end simulation of fluorescence in a photonic crystal is performed: the absorption and emission spectra of a dye on a substrate are calculated by quantum chemistry, and it is shown how the dye emission spectra are modified in a three-dimensional photonic crystal.

Electromagnetic Environmental Effects Testing of Medical Devices Including Those Used for the Treatment of Diabetes

Electromagnetic emissions from technologies that surround us can produce interference with implanted and externally worn medical devices. Electromagnetic environmental effects (E3) testing of medical devices at the Georgia Tech Research Institute (GTRI) began almost four decades ago and continues to incorporate new devices and new sources of electromagnetic emissions as they are developed and become available. The GTRI Medical Device Test Center provides real-world exposure fields to identify interactions and help manufacturers prevent disruptions from the environments in which their devices must function. Typically, the medical device is mounted in or on a torso simulator containing a saline solution that simulates the electrical characteristics of the body. The torso simulator and the device under test are then moved through the fields generated by production security and logistical system technologies using a computer-controlled positioning system. These tests are conducted with different orientations of the medical device to the electromagnetic source, simulating the way in which device wearers interact with these systems in representative situations. Particular E3 test results measured on specific devices in the GTRI Medical Device Test Center are proprietary; however, the results of tests to date with current medical devices used for the treatment of diabetes have been encouraging. These devices have included implantable and externally worn insulin infusion pumps and continuous glucose monitoring systems from different manufacturers. Since E3 tests of diabetes treatment devices to date in the test center have centered on devices from only a few of the many current manufacturers, further testing is warranted. In addition, increased functionality, which is being added to existing devices, will create new possibilities for interference in the future.

Estimation of Rock In-Situ Stress by Acoustic and Electromagnetic Emission

The Kaiser Effect in acoustic emission is often used for an estimation of the stress to which rocks have been subjected. However, there are cases in which the Kaiser Effect is not clear, since the noises due to the contact and/or the stick slip between the pre-induced fracture surfaces are measured during the reloading process. In such cases, estimation of previous stress is difficult by the conventional method which is based on the acoustic emission activity observed under reloading process. In the tests for the Kaiser Effect on rocks, therefore, the noises must be eliminated from the acoustic emission generated from newly created cracks during the second loading process. Such techniques as analysis of the difference between the acoustic emission activity observed in the first and second reloading and the analysis of the change in the slope of the acoustic emission amplitude distribution have been proposed. In this paper we present a new method by which the maximum previous stress in rocks can be directly estimated without any post signal analysis. In the new method, simultaneous measurement of acoustic and electromagnetic emission during loading test of rock sample is employed. The electromagnetic emission in the deformation of rock sample generates only when the fresh surfaces due to cracking are created in the material, and the source of electromagnetic emission is the electrification between the fresh crack surfaces. This paper describes the simultaneous measurement of acoustic and electromagnetic emission useful for estimating the rock in-situ stress.

Characterization of acoustic and electromagnetic emission sources

The creation of cracks is accompanied by electric charge redistribution due to loosened chemical bonds. Electric charges on crack walls create dipole moments. Vibrations of crack walls produce time-dependent dipole moments and, consequently, electric and magnetic fields are generated. An electric signal is induced on metal electrodes. Information about the vibration of crack walls was obtained from this signal analysis. For crack lengths below 1 mm the electrical signal has a frequency of over 2 MHz. In this paper the frequency analysis was performed in a frequency band of up to 5 MHz.

Spherical dipole antenna using optical/electrical converter

AbstractA spherical dipole antenna is studied as a standard electromagnetic emission source in the EMI measurement. Its radiation characteristics are discussed both theoretically and experimentally. One of the antenna elements of a spherical dipole antenna is constructed in the shape of a shield case in which the electronic circuit is installed. Hence, the electromagnetic analysis can be carried out without considering the shape of the electronic circuit into the boundary of the analysis. It is pointed out that the electromagnetic field in not only the far region but in the near region can be computed numerically with high accuracy by means of the mode matching technique.By using a nonmetallic optical fiber instead of a coaxial cable as the signal line, the disturbance of the electromagnetic field by the cable can be neglected. Based on the numerical results, a spherical dipole antenna was fabricated and the radiation characteristics were measured at 30 to 1000 MHz. It was confirmed that the measured data and the numerical results agree within 1.9 dB for the vertical polarization and 1.7 dB for the horizontal polarization. From these results, it is clear that a spherical dipole with radiation characteristics as numerically computed can be realized.

Impulsive (Flash) Phase of Solar Flares: Hard X-Ray, Microwave, EUV and Optical Observations

Recent observations of impulsive hard X-ray, microwave, EUV and optical emissions during solar flares are briefly reviewed in order to deduce the characteristics of the impulsive (flash) phase phenomenon in small solar flares particularly from the point of view of the acceleration of electrons and their role in producing the various impulsive phase emissions. Observed and deduced characteristics of the various electromagnetic emission sources are summarized (Table II). The deduced characteristics of the electron acceleration process (Table III) indicate a process with high acceleration efficiency. The observations are found to be consistent with a model in which electrons are accelerated in a series of short pulses each lasting for ≲ 1 s and the accelerated electrons provide the energy necessary for all the observed electromagnetic emissions produced during the flash phase of small solar flares. Models of the impulsive phase emissions in which energetic electrons play a prominant role are examined and crucial tests to check the accuracy of these models are indicated (Table IV).