Ana Vukicevic

On the Evaluation of Antenna-Mode Currents Along Transmission Lines

In this paper, we derive an integral equation describing the antenna-mode currents along a two-wire transmission line (TL). We show that when the cross-sectional dimensions of the line are electrically small, the integral equation reduces to a pair of TL-like equations with equivalent line parameters (inductance and capacitance). The derived equations make it possible to compute the antenna-mode currents using any traditional TL coupling code with appropriate parameters. The derived equations are tested against numerical results obtained using numerical electromagnetics code (NEC), and reasonably good agreement is found

Common mode current and radiations mechanisms in PLC networks

This paper presents the results of a three-year, in-depth study of the mechanisms of EMC emissions generated by an in-house PLC network. The study was led in close collaboration with the Institute for Information and Communication Technologies, the Swiss Federal Office of Communication and, in the framework of the OPERA project, with the EMC team of the Swiss Federal Institute of Technology, Lausanne. Numerical simulations and experimental measurements of a simplified PLC setup were used to carry out an initial study on a number of aspects of the relation between the radiated field and the common-mode current and the impact of the resonances present in the PLC network. A detailed analysis of a 1:1 scale representative room built on our open area test site, which includes several appliances, power outlets, switched outlets and lighting fixtures in its layout, allowed us to elaborate a simplified electrical model describing the generation mechanisms and the nature of the common-mode current flowing in the power line cables. Several results show that the magnetic near field, close to the wire line, exhibits large spatial variations over the whole frequency range from 1 to 30 MHz, which can be as high as 45 dB due to the resonances taking place in the setup. In addition, variations of the common-mode current as high as 35 dB have been observed, engendering a spread of the K factor of 20 dB. A detailed analysis also revealed large variations in the wave impedance, which ranged from some 50 ohms to more than 1000 ohms depending on the proximity to the standing waves along the line, implying that emission levels can be greatly underestimated or overestimated if their analysis is limited to the magnetic field. Our results indicate that the common-mode current generated along the power-line cables is mainly due to electrical asymmetries stemming mainly from switched loads or switched outlets. Perhaps one of the most important results of this study is the fact that the high variability of the common-mode current along the line makes difficult to evaluate the disturbance potential of a setup from measurements of the CM current at a single point.

On the mechanisms of differential-mode to common-mode conversion in the broadband over power line (BPL) frequency band

The conversion between the common and the differential modes is of great importance in the transmission of data over poorly balanced cables such as electrical wiring. In this paper, we have studied some of the mechanisms involved in this conversion, both experimentally and theoretically. The results show that along-the-line variations in the line parameters be it gradual or abrupt, are responsible for part of the common mode in electric cables. Asymmetries at the source are also responsible for part of the common mode conversion and they can be dominant in certain cases

Review of the Electromagnetic Compatibility PLC Work at the Swiss Federal Institute of Technology (Lausanne) and the University of Applied Sciences of Western Switzerland (Yverdon)

In this paper, we give an overview of the experimental and theoretical PLC-related research work carried out in close cooperation by the Swiss Federal Institute of Technology and the University Of Applied Sciences Of Western Switzerland. The work is conducted in the framework of the OPERA project and of a research contract with OFCOM. It is the EMC aspects of data transmission over power cables that are essentially are covered in this research. Much of the effort is dedicated to the experimental and theoretical characterization of conducted and radiated emissions from poorly symmetrical cables in the LV and MV networks. Our investigations focus in part on the evaluation and possible improvement of the k factor concept. For both, the radiation and the conducted emissions problems, a key issue studied is the common/differential mode conversion phenomena in the lines. Other work includes the study of emissions mitigation techniques and immunity test methods

A concept to enhance system data rate for PLC access networks

This paper presents an approach to divide a PCL single-master operated cell into multiple sub-cells featuring each an individual master (i.e. multi-master), in order to increase the overall system data rate. This is achieved by using blocking filters to allow frequency reutilization. Measurements were carried out in the village of Saint Sulpice, near the city of Lausanne in Switzerland, in order to verify the concept and the possible use of the blocking filters. Our results show that the radio frequency (RF) separation obtained using blocking filters is, in certain cases, effective enough to properly separate signals belonging to different low voltage (LV) feeders on the same substation. In some other cases, despite the use of properly designed and integrated blocking filters, additional mechanisms must be used. In particular, the Synchronised Tx/Rx for all masters and the Rx/Tx frequency duplexing mechanisms are discussed.

Experimental verification of common-mode current generation in home electrical wiring in the Powerline Communications Band

In this paper, we test experimentally the hypothesis that the common mode current at any point in an in-house electrical network can be calculated as the linear combination of two types of sources, namely the input differential mode voltages and the input common mode currents. The results show an excellent agreement between theory and measurements, thus lending strong support to the hypothesis.

On the efficiency of notching technique to reduce EM radiations from PLC networks

In this paper, we show the results of laboratory measurements aimed at studying, under controlled conditions, different characteristics of notching in OPERA PLC modems, such as total and effective notch width, notch depth, maximum notch depth, etc. In addition to the laboratory measurements, we made field measurements that showed that the expected notch characteristics are also present in real PLC systems. Our measurements showed that notching is a useful technique to avoid interference with existing services.

Impact of the Symmetry of Coupling-Decoupling Networks on the Conducted Immunity Testing of PLC Modems

For conducted immunity testing, the injection of the test common mode signal is achieved by way of the couplingdecoupling network (CDN) whose symmetry is not defined in the standards. Due to the low symmetry of PLC cabling, part of the injected common mode test signal is converted into a differential mode signal that interferes with the wanted signal at the input of the modem being tested. We show in this paper that the expected bit error rates due to the differential mode current from the CDN are of the order of 1×10−5 to 5×10−5, which can be handled by coding and MAC ARQ procedures. We also show that it is unlikely that the differential mode signals from the CDN#2019;s finite LCL will overload the modems.