Antenna using a magnetic-slab located in the principal magnetic-field region beneath the patch

This paper presents an analysis of microstrip patch antennas with different dielec-tric/magnetic substrate profiles in an attempt to obtain operating frequency reduction. Initially, different ridge shapes in the substrate were examined. An in-depth investigation of the ridge shape and its dimensions on the antenna performance has been carried out. Subsequently an antenna with a magnetic-slab loaded in the prime magnetic-field region beneath the patch is proposed. The new magnetic loaded antenna design is aimed to reduce the resonant frequency of a conventional patch and reduce the profile of an earlier design with a substrate ridge. Various magnetic materials have been embedded within the original dielectric substrate of the patch antenna. Measured results validated the hypothesis that this frequency can be reduced by placing magnetic materials at the centre of the patch. The achieved gain is expected to be further enhanced by using forthcoming magnetic materials with improved performance

Computational models of learning and beyond: Symmetries of associative learning

The authors propose in this chapter to use abstract algebra to unify different models of theories of associative learning -- as complementary to current psychological, mathematical and computational models of associative learning phenomena and data. The idea is to compare recent research in associative learning to identify the symmetries of behaviour. This approach, a common practice in Physics and Biology, would help us understand the structure of conditioning as opposed to the study of specific linguistic (either natural or formal) expressions that are inherently incomplete and often contradictory

Aspects of harmonisation of individual monitoring for external radiation in Europe: Conclusions of a EURADOS action

Following the publication of the EU Council Directive 96/29, EURADOS coordinated two working groups (WGs) for promoting the process of harmonisation on individual monitoring of occupationally exposed persons in Europe. An overview of the major findings of the second WG is presented. Information on the technical and quality standards and on the accreditation and approval procedures has been compiled. The catalogue of dosimetric services has been updated and extended. An overview of national regulations and standards for protection from radon and other natural sources in workplaces has been made, attempting to combine the results from individual monitoring for external, internal and workplace monitoring. A first status description of the active personal dosemeters, including legislative and technical information, and their implementation has been made. The importance of practical factors on the uncertainty in the dose measurement has been estimated. Even if a big progress has been made towards harmonisation, there is still work to be don

Bistable chromatic switching in Yb3+ doped NdPO4 crystals

Pump-induced chromatic switching is reported for an 808 nm pumped Yb3+ -doped NdP O4 crystal. This effect is based on the interplay between the Nd3+ \u2194 Yb3+ energy transfer processes and on the large pump-induced thermal loading characteristic of this neodymium compound. For temperatures below 300 K, a noticeable hysteresis is observed in the relative Nd3+ and Yb3+ contributions to the emission spectra; this leads to a bistable chromatic switching. This optical bistability is related to a nonlinear pump-induced heating rate that produces abrupt changes in the local temperatur

Calculating Double-Exponential Diode Model Parameters From Previously Extracted Single-Exponential Model Parameters

A procedure is proposed to calculate both pre-exponential reverse currents of the double-exponential model of a diode\u27s currentvoltage experimental characteristics from previously extracted reverse current and diode quality factor of the diode\u27s singleexponential model. The procedure is illustrated by modelling the drain-body junction of a MOSFET including its parasitic series resistance. © 1995, IEE. All rights reserved

Discovering the puzzling behaviour of electrons with the Grimaldi-Young experiment

An experiment analogous to that devised by Grimaldi and subsequently repeated by Young to study the nature of light has been realized with electrons. Following the Grimaldi and Young line of thought, an original approach is presented to introduce undergraduate physics students to the wave behaviour of electrons