A rectangular waveguide cell for measurement of the shielding effectiveness of anisotropic materials

A method for measuring the shielding effectiveness of planar anisotropic materials using a rectangular waveguide cell is proposed. Computational models are used to verify the behaviour of the cell and validate its ability to measure shielding effectiveness. Results of measurements on a control sample and three carbon-fibre composite laminates in a GTEM cell are presented. A dynamic range of 70 dB with a capability to discriminate 20 dB of anisotropy is achieved in the frequency range 400-1600 MHz using cubic cells of side length 200 mm and 300 mm

Coupling of Energy Into PCB Traces in a Reverberant Environment: Absorption Cross-section and Probability of Susceptibility

Predicting the risk of susceptibility to electromagnetic interference for a system would be of significant interest to the EMC community. In this paper, we consider the coupling of electromagnetic energy into Printed Circuit Board (PCB) traces and how it relates to the power balance model of shielding effectiveness. We show results of some measurements of the absorption cross-section of a load on a PCB trace and compare them with previously published results

Seizing the Moment: Realizing the Promise of Student-Centered Learning

This brief outlines policy recommendations for supporting student-centered learning at the local, state, and federal level

Characterization and modelling of electromagnetic interactions in aircraft

This article describes the development of modelling techniques and simulation tools for the electromagnetic (EM) analysis of aircraft. It is shown that hybrid solvers and multi-scale techniques can be used effectively to analyse the EM response of aircraft. The importance of supplementing models with appropriate measurement and characterization techniques for parameter extraction and for validation is also demonstrated

A method for the measurement of shielding effectiveness of planar samples requiring no sample edge preparation or contact

A method is presented for the measurement of shielding effectiveness of planar materials with nonconducting surfaces such as carbon fiber composites. The method overcomes edge termination problems with such materials by absorbing edge-diffracted energy. A dynamic range of up to 100 dB has been demonstrated over a frequency range of 1-8.5 GHz, depending on the size of the sample under test. Comparison with ASTM D4935 and nested reverberation measurements of shielding effectiveness shows good agreement

Experimental characterization of the response of an electrical and communication raceway to IEMI

This paper reports the results of two experimental campaigns aimed at studying the high-frequency response of a raceway containing low voltage power, telephone, and Ethernet cables, to external electromagnetic field illumination. The raceway was tested against HPEM transients inside a GTEM cell and low power fields inside a reverberation chamber (RC). The HPEM tests revealed that the low voltage power cables have the greatest coupling under a hyperband illumination, compared to telephone and Ethernet cables. The RC tests allowed the determination of statistical transfer functions from random incident field configurations into DM voltage in cable loads. The responses were found to be governed by the raceway under test at the lower frequencies (below 1 GHz). Between 0.2-1 GHz, the raceway gives about 10 dB higher coupling than a short patch cable. The difference is even greater at lower frequencies and for shielded cables. In the frequency band 1-3 GHz, little difference was observed between short patch cables and the full raceway, but both were still significantly higher than direct coupling to the measurement card. Beyond 3 GHz, the coupling is clearly dominated by the terminal equipment. The experiments performed in this work provide a better understanding of the expected induced voltages and currents in commercial cable systems when exposed to IEMI-like signals

The prevalence and incidence of mental ill-health in adults with autism and intellectual disabilities

The prevalence, and incidence, of mental ill-health in adults with intellectual disabilities and autism were compared with the whole population with intellectual disabilities, and with controls, matched individually for age, gender, ability-level, and Down syndrome. Although the adults with autism had a higher point prevalence of problem behaviours compared with the whole adult population with intellectual disabilities, compared with individually matched controls there was no difference in prevalence, or incidence of either problem behaviours or other mental ill-health. Adults with autism who had problem behaviours were less likely to recover over a two-year period than were their matched controls. Apparent differences in rates of mental ill-health are accounted for by factors other than autism, including Down syndrome and ability level