Conformity Magazine - February 2009 - (Page 40)

below compliance values only in the low frequency range (i.e., below 0.8GHz). However, a consistent increased number of resonances can be detected when comparing this case to the floating optical module (see Figure 18b). This is probably due to the power plane resonances of the PCB excited by the module mounted on it. This explanation is confirmed by a plot of the E field magnitude over a crosssection of the mounted module. Figure 19 illustrates the E field magnitude for two different frequencies, and it is possible to see that the near field value related to the higher frequency (20GHz) presents field strengths almost exclusively related to the PCB. In particular, in Figure 18b, the shape of the PCB is well defined, as are the red spot regions around the board edges. In order to study and improve the shielding performance, the optical module should be simulated as an isolated device, and also as mounted device, since the emissions profile is strongly affected by the near field distribution, and the latter is related to the actual dimension/shape of the PCB. Conclusions This article has described a simulation strategy for RFI/EMI analysis of PCBs in complex system environments, as well as their radiated emissions profile in an early design phase before a prototype has been manufactured. The proposed workflow consists of three steps: 1) simulation of the complex PCB by means of a dedicated solver, based on quasi-static PEEC, 2) near field calculation and generation of surface current distribution; and 3) full wave simulation of the metallic enclosure in order to analyze the shielding effectiveness and the radiated emissions. a b Figures 14a and 14b: a) EMC radiation at 3 meters from the optical transceiver (frequency range 5-40GHz), case 1; and b) magnetic field distribution at 10 GHz (left side) and 30GHz (right side) Figure 16: EMC radiation at 3 meters from the optical transceiver: comparison among cases 1, 2 and 3 Figure 15: Calculation domain with a close up on the transceiver and mesh view with in evidence the MSS. 0 Conformity february 2009 Figure 17: Optical transceiver as mounted device

Table of Contents Feed for the Digital Edition of Conformity Magazine - February 2009

Conformity Magazine - February 2009 Contents Editor's Note FCC Clarifies Closed Captioning Requirements for DTV Receivers Commission Cracks Down (For the Fifth Time!) On Junk Fax Marketer FDA Requests Comments on Global Harmonization Documents Australia Now Requires Solar Panel Testing and Certification EU Drafting New Directive on Toy Safety EU Commission Revises Standards List for EMC, R&TTE Directives Additional Standards Published For the EU's Medical Devices Directive EU Commission Publishes Additional Standards for Directives on Active Implantable, In Vitro Medical Devices EMC For the Functional Safety of Automobiles ESD Open Forum The ILAC Arrangement: Facilitating Trade Efficient Methodology for the EMI Analysis of Optical Transceivers Including PCBs and/or Flex Circuits The EuP Directive - Implementation, Design Requirements and Issues Chambers, Shielding, and Accessories Buyer's Guide CPSIA Lead Requirements Apply to Existing Inventory, Says CPSC CPSC Clarifies Certifcation Requirements Other CPSC Actions in the News IEC Standards Update Product Reviews UL standards Update Telcordia Standards Update From Our "You Can't Make This Stuff Up" Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - February 2009

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