Showing papers by "T.P. Van Doren published in 2000"
TL;DR: In this paper, the FDTD model was used to investigate the EMI from a test enclosure with slots and apertures excited by interior sources in a rectangular test enclosure, and the results indicated that radiation at cavity mode resonances through slots and aperture modes of nonresonant dimensions can be as significant as radiation at aperture or slot resonances.
Abstract: Electromagnetic interference (EMI) from slots and apertures resulting from coupling of interior sources through enclosure cavity modes in a rectangular test enclosure is reported. EMI from a specially designed test enclosure with slots or apertures excited by interior sources was studied experimentally and with finite-difference time-domain (FDTD) modeling. The measurements and FDTD modeling agree well. The results indicate that radiation at cavity mode resonances through slots and apertures of nonresonant dimensions can be as significant as the radiation at aperture or slot resonances. The agreement between the FDTD modeling and measurements demonstrates the usefulness of FDTD for investigating aspects of shielding enclosure design such as coupling to slots and apertures and slot interactions.
165 citations
TL;DR: In this article, a simple design equation for the relation between aperture size and number and shielding effectiveness is proposed to investigate the mutual coupling between apertures in an infinite conducting plane.
Abstract: Aperture arrays designed to provide airflow through shielding enclosures can provide part of the coupling path from interior sources to external electromagnetic interference (EMI). In this work, radiation through aperture arrays is investigated numerically and experimentally. FDTD modeling is compared with measurements on aperture arrays in a test enclosure. The method of moments (MoM) is also utilized to study radiation from apertures and to investigate the mutual coupling between apertures in an infinite conducting plane. A simple design equation for the relation between aperture size and number and shielding effectiveness is proposed.
83 citations
21 Aug 2000
TL;DR: In this paper, the fundamental behavior of PCB power bus structures using the modal expansion method is analyzed and validated by experiments and full-wave numerical modeling, and it is shown that the power bus can be modeled as a series L/sub e/C circuit below the first board resonance frequency.
Abstract: This paper analyzes the fundamental behavior of PCB power bus structures using the modal expansion method. The results are validated by experiments and full-wave numerical modeling. It is shown that the power bus can be modeled as a series L/sub e/C circuit below the first board resonance frequency. C is the interplane capacitance and L/sub e/ is an effective inductance contributed by all the cavity modes. The effects of the layer thickness, port location, board size and the feeding wire radius on the value of L/sub e/ are discussed in this study. L/sub e/ can be estimated from the geometry parameters of the test board. The goal is to obtain a simple model that can be used to analyze the power bus impedance below the first board resonance.
44 citations
21 Aug 2000
TL;DR: In this article, a 1GHz TEM cell was used to measure the radiation from microstrip lines with different kinds of bends and a full wave hybrid FEM/MoM code is used to compute the radiation.
Abstract: This paper investigates the radiation from microstrip lines with 90-degree bends. A 1-GHz TEM cell is used to measure the radiation from microstrip lines with different kinds of bends. A full wave hybrid FEM/MoM code is used to compute the radiation. Both experimental and numerical results show that there is no significant difference between the radiation from right angle bends and bends with two 45-degree corners at frequencies and trace dimensions that are likely to be found on printed circuit boards.
19 citations
TL;DR: In this article, a general EMI reduction of more than 20 dB was achieved for dual-perforated screens spaced 1 cm apart when compared to EMI for a single perforated screen.
Abstract: Airflow perforations in shielding enclosures can act as apertures facilitating the coupling from internal sources to external electromagnetic interference (EMI). This EMI radiation for single- and dual-screen configurations was studied herein experimentally and with finite-difference time domain (FDTD) modeling. A general EMI reduction of more than 20 dB was achieved for dual-perforated screens spaced 1 cm apart when compared to EMI for a single perforated screen. However, in the dual-screen case, the space between the screens can act as a thin cavity, which, in turn, can lead to significant radiation at distinct angles. Damping the resonances by loading the space between the screens with lossy material mitigates this problem and achieves more than 20-dB reduction over a single screen.
19 citations
21 Aug 2000
TL;DR: In this article, the increase in EMI as a trace is routed increasingly closer to the PCB edge has been studied experimentally and with numerical modeling, and design maxims concerning traces near board edges are not well quantified.
Abstract: PCB traces routed near board edges and carrying high-speed signals are considered to contribute to EMI problems. Consequently, design maxims state that traces that might have intentional or unintentional high frequency components on them be kept away from board edges. This costs valuable surface area as boards become more densely designed. Further, design maxims concerning traces near board edges are not well quantified. The increase in EMI as a trace is routed increasingly closer to the PCB edge has been studied experimentally and with numerical modeling.
13 citations
21 Aug 2000
TL;DR: In this article, the effect of decoupling capacitors placement on a 4-layer printed circuit board is examined, and design guidelines are provided to determine where to place the high-frequency decoupled capacitors.
Abstract: The switching of active devices on printed circuit boards (PCBs) can cause a momentary surge or drop in the power bus voltage. Decoupling capacitors are often utilized to alleviate this problem. They help to stabilize the power bus voltage by supplying transient current to active devices. The decoupling strategy, including where to place the high-frequency decoupling capacitors, is often a topic of debate. This paper examines the effect of decoupling capacitor placement on a 4-layer printed circuit board. Some design guidelines are provided.
6 citations
21 Aug 2000
TL;DR: In this paper, the authors describe a case study covering the evaluation and reduction of the radiated EMI from an 18" liquid crystal display (LCD) monitor, which was completed in two parts: first potential EMI sources at the printed circuit board (PCB) level were identified, then the EMI antennas driven by these sources were analyzed.
Abstract: This paper describes a case study covering the evaluation and reduction of the radiated EMI from an 18" liquid crystal display (LCD) monitor. The evaluation was completed in two parts: first potential EMI sources at the printed circuit board (PCB) level were identified, then the EMI antennas driven by these sources were analyzed. Methods for reducing the EMI were described in detail, and where applicable, those modifications were applied. Radiated measurements demonstrate the effectiveness of these recommendations.
6 citations