Conformity Magazine - March 2008 - (Page 53)

in this case, which shows the high performance of honeycomb panels. Often the system to be analyzed is more complex [11]. As an example, Figure 8 depicts a real view and the correspondent electromagnetic model of the loaded monopole antenna used to perform measurements inside a semi-anechoic chamber. The antenna consists of two disks, with a radius of r=48mm, a thickness of t=0.5mm, 1mm distant from each other, and separated by a dielectric material with relative electric permittivity of er=8. The leg’s length is h=95mm, and the first resonance frequency is at 0.65GHz. The results obtained by means of measurements are presented in Figure 9, where the vertical and horizontal (Ex and Ey) electric field components registered 3m distant from the metallic opened rack are compared with the corresponding results coming from the numerical simulation. Good agreement is also achieved in this case for both components. Integration of Analysis Tools Another useful capability of EMC simulation software is the ability to operate in an integrated analysis environment, using the same model developed for mechanical/thermal analysis in the evaluation of EMC at the early design stages. This is valuable because thermal design often conflicts with EMC design, and fixes that are implemented to address thermal concerns often exacerbate or create EMC problems. The most typical example is that thermal design requires large holes to enable adequate airflow, while EMC design requires small holes to reduce emissions. A hole will pass electromagnetic fields in and out of the enclosure if one or more of its dimensions are equal to or larger than the wavelength of the field. As mechanical engineers begin to develop the physical design, they can drag the PCB model and drop it into a systemlevel thermal design. An integrated analysis environment not only ensures the transmission of accurate information to mechanical engineers, but also provides immediate notification of design changes. The same model that is created for system level thermal analysis can also be used to address EMC issues far earlier than is normally possible. Figure 10 illustrates a complex metallic rack used for telecommunication equipment. The IGES mechanical file format can be easily imported into the simulation software tool and numerically simulated in order to obtain results in the Nearfield and/or farfield region. Conclusions This article has offered an overview of the different approaches which can be employed to address the challenging EMC-EMI analysis of complex PCBs located inside a metallic enclosure. It has also investigated possible workflow process, marCh 2008 Conformity 53 http://www.sme.org/westec http://www.sme.org/westec

Table of Contents Feed for the Digital Edition of Conformity Magazine - March 2008

Conformity Magazine - March 2008 NewsBreaks Editor's Note Adelstein Renominated to the FCC Industry Canada Publishes FAQs On RF Fields FDA Gives Its Scientific Capabilities Poor Marks FDA Offers Guidance On its Product Review Process FDA Publishes Updates to List of Recognized Standards FDA Warns of Patient Risk From Electric Dental Handpieces Complying with the EMC Directive, Second Edition ESD Open Forum Emerging Issues in Standards - Korean "RoHS": Not Like RoHS at All The iNARTE Informer Challenges in Testing - Field-Induced Charged Device Model: What Really Happens Design Fundamentals - EMI Shielding Technologies for Consumer Electronics Equipment Focus On...Compliance Software Buyer's Guide Additional Standards Published for the EU's ATEX Directive Additional Standards for the EU's Medical Devices Directive Also Published China to Require Bar Codes to Enhance Product Safety CPSC Releases 2007 Self-Assessment CPSC Actions in News IEC Standards Update UL Standards Update Product Reviews Telcordia Standards Update From Our "You Can't Make This Stuff Up" Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - March 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.