Daniele Desideri

Dual-PEEC Modeling of a Two-Port TEM Cell for VHF Applications

Two-port TEM cells with rectangular cross section are commonly used to produce plane electromagnetic waves with high electric field. The non-uniform structure makes the use of numerical methods extremely useful in the design phase in order to achieve a very good behavior of the TEM cell over a wide frequency range of operation. In this paper an extended version of PEEC is used to study a real device and results are compared with experimental ones.

Coaxial Waveguide Methods for Shielding Effectiveness Measurement of Planar Materials Up to 18 GHz

The issue concerning the measurement of the shielding effectiveness (SE) of planar materials over a wide frequency range is of crucial relevance in several electromagnetic compatibility applications. This paper describes three different coaxial specimen holders for the measurement of the SE of thin metallic films over a nonconducting substrate or sandwiched between two insulating layers from a few kHz up to 18 GHz. Besides the well-known ASTM D4935 flanged coaxial cell, two novel versions of coaxial fixtures with an interrupted and continuous inner conductor are presented and compared. Their limits of applicability, advantages, and drawbacks are discussed with respect to frequency, sample characteristics, and test procedure. The analysis is performed by the use of simple equivalent circuit models, experimentally validated measuring thin copper films of different thicknesses which are deposited on kapton substrates by magnetron sputtering. It is demonstrated that the use of the three methods, properly combined, provides reliable SE results in the overall considered frequency range. It is also shown that the measurement of conducting films between two dielectric layers is critical at frequencies lower than some tens of MHz.

Characterization of a DC magnetron sputtering device

Purpose – The aim of this paper is to obtain an extensive experimental characterization of a DC magnetron sputtering device used for plasma processing of materials.Design/methodology/approach – Models and measurements are combined for an interdisciplinary characterization of a DC magnetron sputtering device. Langmuir probes are used for the plasma characterization; the magnetic field is measured by using Hall probes and the data are used to validate a magnetostatic three‐dimensional numerical analysis of the device; precision mechanical measurements are done for the target erosion profile and the results are related to a simple estimation formula; a simple model is proposed for the target heating.Findings – Data on magnetic and electric fields, electron temperature and density, plasma potential and target erosion are provided. An estimation of the target heating is proposed. Finally, an application concerning thin film deposition is reported.Research limitations/implications – Measurement of the target su...

Characterization of nanostructured copper films for electromagnetic shield

Purpose – The purpose of this paper is to obtain a multidisciplinary characterization of nanostructured copper films for electromagnetic shields.Design/methodology/approach – Structural and electrical analysis have been applied, on copper nanometric films produced by a magnetron sputtering device.Findings – Data are provided for copper films realized by magnetron sputtering deposition on glass, in different operating conditions.Practical implications – A multidisciplinary comprehension of shielding effectiveness of nanostructured thin films can be important in many applications where there are electromagnetic compatibility problems.Originality/value – The paper gives a valuable set of information for the characterization of nanometric copper thin films.

Identification of an equivalent model for the permanent magnets of a magnetron sputtering device

Purpose – The aim of the work was to obtain an auxiliary instrument able to give the magnetic configuration of a magnetron sputtering device for operation with targets, magnetic and non magnetic, with different heights, starting from a device with no detailed information of the source.Design/methodology/approach – An inverse problem has been dealt with. A 2D numerical analysis has been performed, which utilizes as a starting point a model identified with a simple analytical procedure based on measurements.Findings – A satisfactory equivalent model has been identified, and validated in several different conditions.Originality/value – The proposed approach can be applied when no detailed information of the source is available, in the case of a cathode without a ferromagnetic yoke.

Shielding effectiveness of construction materials

Shielding effectiveness measurement, up to the GHz range, of construction materials with different compositions is an important issue. In this paper a coaxial waveguide, originally developed for thin films, is proposed as a simple device able to perform measurements on test samples with a thickness of a few millimetres. A calibration of the test system, with length extended of 5 mm, has been done both with a theoretical evaluation and an experimental measurement. Data obtained with construction materials of current interest for research are presented. With respect to similar systems reported in literature, where data up to 1.5 GHz are shown, this system has proven to be appropriate for measurements up to 3 GHz without too stringent tolerances in the sample geometry and without contact problems. Moreover, with inorganic polymers test samples, a clear relation between shielding effectiveness and heating temperature of the material has been observed.

Human exposure to pulsed current waveforms below 100 kHz

A tool for the analysis below 100 kHz of pulsed current waveforms with reference to human exposure has been developed. It consists of a dedicated program written in Matlab. As input data, a trapezoidal pulsed current waveform has been considered, and, varying the rise time and the duty-cycle, a parametric analysis has been performed. Also a noise superimposed to the signal has been considered. Parameters relevant to human exposure have been calculated following the ICNIRP Guidelines. A schematic operative diagram for metal inert gas welding applications is proposed; an experimental set-up has been built and the obtained results are reported.

Electric Field Under an MV Line Supported by Concrete Poles

This paper presents a study of the electric field under a three-phase medium voltage (MV) power line supported by concrete poles. The analyzed configuration is a pole-top-pin construction. An analytical model has been developed for the three-phase wires assuming three straight cylindrical conductors whose axes have been put parallel to each other and to the ground, and for the concrete pole a cylindrical conductor placed in a vertical position. Simple analytical formulas have been obtained for the three components of the electric field in the vertical plane containing the axis of the conductor representing the central top wire. The validity range of the model is from the ground to one quarter of the height of the concrete pole. The analytical expressions have been checked against the numerical data obtained by a 3-D numerical analysis performed by using the charge simulation method. Finally, the results have been experimentally validated. The analytical model reported here is a new easy tool for the evaluation of the electric field for the analyzed geometry.

MV line electric field evaluation near a concrete pole

The paper presents a study of the electric field near a concrete pole supporting the three-line conductors of an MV three-phase three-wire power line. The analysis has been carried out firstly by means of two three-dimensional (3-D) numerical codes based on the finite element method (FEM) and the charge simulation method (CSM), whose results have been compared for validation purposes. Then a simple analytical model of the field distribution near the pole has been developed, whose results have been checked against the numerical data. A measurement campaign was also carried out, at the aim of a final validation of both numerical data and analytical results. A good agreement was found, as shown in the paper. The analytical model is suitable for an easy implementation in low-cost microprocessor devices to be installed on the concrete poles in order to perform the remote detection of nonsymmetric ground faults occurring at any distance along the line.

Aluminium nitride films on glass

Purpose of this work is to realize AlN films with preferred crystal orientation on a magnetron sputtering system at different pressure values, in particular towards low-pressure gas discharge operative range, where few data are available in literature. In this respect, explored operative pressures have been 0.07 and 0.12 Pa, together with the more common values of 0.3 and 0.7 Pa. Reactive Ar-N2 mixtures (50%-50% and 0%-100%) and a DC-pulsed power supply have been used, and films have been deposited on glass substrate. Films thicknesses have been measured with surface profiler, and XRD analyses have been performed. Experimental data are presented; the best results with respect to adhesion, deposition rate and film crystallinity with the same deposition time have been obtained with mixtures 50% Ar - 50% N2 at 0.12 and 0.3 Pa.