An analytical formulation has been developed for the shielding effectiveness of a rectangular enclosure with an aperture. Both the magnetic and electric shielding may be calculated as a function of frequency, enclosure dimensions, aperture dimensions and position within the enclosure. Theoretical values of shielding effectiveness are in good agreement with measurements. The theory has been extended to account for circular apertures, multiple apertures, and the effect of the enclosure contents.

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Analytical formulation for the shielding effectiveness of enclosures with apertures

The hands-on, example-rich guide to modeling and simulating advanced communications systemsSimulation is an important tool used by engineers to design and implement advanced communication systems that deliver optimal performance This book is a hands-on, example-rich guide to modeling and simulating advanced communications systems The authors take a systems-level approach, integrating digital communications, channel modeling, coding, elementary statistical estimation techniques, and other essential facets of modeling and simulation This is the first book to present complete simulation models built with MATLAB that can serve as virtual laboratories for predicting the impact of system design changes Coverage includes: Role of simulation in communication systems engineering Simulation approaches and methodologies Signal and system representations, filter models, noise generation, Monte Carlo simulation, and postprocessing Advanced techniques for modeling and simulating nonlinear and time-varying systems Waveform level and discrete channel models Performance estimation via Monte Carlo simulation Semianalytic simulation techniques Variance reduction techniques Co-channel interference in wireless communication systems, and more The authors also present detailed case studies covering phase-locked loops, CDMA systems, multichannel nonlinear systems, as well as a start-to-finish simulation of an advanced cellular radio systemPrentice Hall Series in Communications Engineering & Emerging Technologies, Theodore S Rappaport, Editor

Principles of Communication Systems Simulation with Wireless Applications

We describe techniques for making sensitive and high-dynamic-range measurements of laser amplitude and envelope phase noise (timing jitter) in the frequency domain at the shot-noise limit. Examples of amplitude noise measurements on continuous-wave argon-ion and diode-pumped solid-state lasers used for pumping a femtosecond Ti:sapphire laser are presented. Amplitude and phase noise measurements for the Ti:sapphire laser are also presented, showing correlation between pump laser amplitude modulation (AM) spectra and the resulting AM and phase noise. Characteristics of the measurement system components are discussed, along with examples of the impact these have on achieving reliable high-dynamic-range measurement capability.

High-dynamic-range laser amplitude and phase noise measurement techniques

Noise on a dc power-bus that results from device switching, as well as other potential mechanisms, is a primary source of many signal integrity (SI) and electromagnetic interference (EMI) problems. Surface mount technology (SMT) decoupling capacitors are commonly used to mitigate this power-bus noise. A critical design issue associated with this common practice in high-speed digital designs is placement of the capacitors with respect to the integrated circuits (ICs). Local decoupling, namely, placing SMT capacitors in proximity to ICs, is investigated in this study. Multilayer PCB designs that employ entire layers or area fills for power and ground in a parallel plate structure are considered. The results demonstrate that local decoupling can provide high-frequency benefits for certain PCB geometries through mutual inductive coupling between closely spaced vias. The associated magnetic flux linkage is between the power and ground layers. Numerical modeling using an integral equation formulation with circuit extraction is used to quantify the local decoupling phenomenon. Local decoupling can effectively reduce high-frequency power-bus noise, though placing capacitors adjacent to ICs may limit routing flexibility, and tradeoffs need to be made based on design requirements. Design curves are generated as a function of power-bus layer thickness and SMT capacitor/IC spacing using the modeling approach to quantify the power-bus noise reduction for decoupling capacitors located adjacent to devices. Measurement data is provided to corroborate the modeling approach.

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Quantifying SMT decoupling capacitor placement in dc power-bus design for multilayer PCBs

We report on a new principle yielding enhanced electromagnetic shielding, using as an example a composite comprised of carbon nanotubes (CNTs) integrated with a reactive ethylene terpolymer (RET). Such composites were synthesized through the chemical reaction of the functional groups on the CNT with the epoxy linkage of the RET polymer. The main advantages of these composites include good dispersion with low electrical percolation volume fractions (~0.1 volume%), yielding outstanding microwave shielding efficiency for electromagnetic interference applications. The shielding effectiveness was characterized for both single-walled and multiwalled CNT-based composites and was much enhanced in the former. The specific roles of absorption and reflection in determining the total shielding, as a function of the nanotube filling fraction, is also discussed.

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У Отт Генри

Papers

Методы подавления шумов и помех в электронных системах. (Noise reduction techniques in electronic systems)