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  • 1
    Electronic Resource
    Electronic Resource
    Electrical characterization of some materials in the X-band (1990)
    Springer
    Journal of materials science 1 (1990), S. 105-109 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Three classes of materials, i.e. dielectric, semiconducting and conducting materials are considered, where some of their electrical properties are measured at microwave frequencies, i.e. in the X-band (8 to 12 GHz). These include the insertion loss, return loss, shielding effectiveness and the equivalent input impedance. Comparison between these different parameters is made using a set of curves as a function of frequency. The results obtained indicate virtually no unusual behaviour. A maximum shielding efficiency of about 34 dB is found for GaAs limit and lower values are found for the silicon, flexible carbon and dielectric materials. The equivalent input impedance was found to be roughly constant over the X-band for the dielectric and conducting materials while it exhibits a high dependence on frequency for semi-conducting material oscillating between inductive and capacitive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694917
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Measurements of the “Magnex DC” characteristics at microwave frequencies (1988)
    Springer
    Journal of materials science 23 (1988), S. 2995-3000 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper deals with the measurements of the equivalent impedance, insertion loss (IL), and return loss (RL) of a conductive composite material called “Magnex DC”, performed at microwave frequencies. It is found that the equivalent impedance of this composite material decreases as the frequency increases in the X-band (8–12.4 GHZ) and the IL of a 1.4 mm thick specimen is greater than 9 dB over the whole band. The utilization of this material in electromagnetic shielding is considered. Furthermore, results of the measurements performed on a tapered specimen are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547481
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanical and electrical behaviour of “Magnex DC” conductive polymer composite (1989)
    Springer
    Journal of materials science 24 (1989), S. 1309-1315 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Mechanical and electrical behaviour of the “Magnex DC” conductive polymer composite is reported. X-ray diffraction patterns and scanning electron microscopy (SEM) show that the composite has a semicrystalline, isotropic, and defected structure. It was found that both the elastic modulus and yield stress increase with decreasing temperature; the yield stress increases nonlinearly with increasing strain rate due to the voids in the composite. In addition, the activation energy and the activation volume of a single rate-activated process observed at relatively high strain rates are determined. The dependence of the impedance behaviour on frequency is investigated. It was observed that the a.c. conductivity is almost independent of frequency below 10 kHz and increases with frequency above this range. The values obtained for the conductivity indicate that the composite has a relatively small electrical conduction which is rather less than that for the pure semiconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553159
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Microwave properties of the talc filled polypropylene (1989)
    Springer
    Journal of materials science 24 (1989), S. 1795-1800 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A microwave bench operating in the frequency range 8–12 GHz (X-band) was used to investigate some of the electrical characteristics of the talc filled polypropylene composite. The impedance, return loss, and insertion loss are measured as a function of frequency in the X-band range. It was found that electromagnetic waves interact with the material via the impurities, inclusions and voids existing in the bulk composite. The impedance, return loss and insertion loss show relatively low frequency dependence. Also, the return loss and the impedance exhibit a resonance behaviour at 11.91 GHz. The results suggest that this composite material could be used in some microwave applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01105707
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanical and electrical behaviour of “Magnex DC” conductive polymer composite (1989)
    Springer
    Journal of materials science 24 (1989), S. 1309-1315 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Mechanical and electrical behaviour of the “Magnex DC” conductive polymer composite is reported. X-ray diffraction patterns and scanning electron microscopy (SEM) show that the composite has a semicrystalline, isotropic, and defected structure. It was found that both the elastic modulus and yield stress increase with decreasing temperature; the yield stress increases nonlinearly with increasing strain rate due to the voids in the composite. In addition, the activation energy and the activation volume of a single rate-activated process observed at relatively high strain rates are determined. The dependence of the impedance behaviour on frequency is investigated. It was observed that the a.c. conductivity is almost independent of frequency below 10 kHz and increases with frequency above this range. The values obtained for the conductivity indicate that the composite has a relatively small electrical conduction which is rather less than that for the pure semiconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397064
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Some properties of nickel-coated carbon fibre-polypropylene composite at microwave frequencies (1990)
    Springer
    Journal of materials science 25 (1990), S. 3083-3088 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Some properties of nickel-coated carbon fibre-polypropylene composite are considered at microwave frequencies in the range 8 to 12 GHz. The paper presents the measured values of the insertion and return losses and the equivalent input impedance in the above frequency band. Measurements were performed on composite material for different nickel-coated fibre concentrations of 0, 5, 10, 16 and 28 wt%. The filler effects shows a transition region and identifies the dependency of the electrical properties on these concentrations. Furthermore, shielding effectiveness is calculated for the given concentrations and it is found that its value could reach more than 30 dB over the whole frequency band for a specimen of 2.6 mm thickness and with 28 wt% concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587654
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Electrical properties of oilshale rocks (1991)
    Springer
    Journal of materials science 26 (1991), S. 203-207 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The characterization of electric properties of oilshale deposit is reported. The scanning electron microscopy and the results of the dielectric constants show that the deposit is a heterogeneous composite material containing some conducting and insulating microstructural units. The components of the equivalent input impedance measured at microwave frequencies (8 to 12 GHz) and the impedance at low frequencies (0.5 Hz to 30 kHz) showed frequency dependence. The real and imaginary components of the permittivity determined from the impedance data obtained at low frequencies showed an exponential decrease with frequency. The observed frequency dependence of the rock permittivity is ascribed generally to a Maxwell-Wagner type of mechanism. Also it was observed that the conductivity is almost independent of the frequency below 1 kHz and increases with frequency above this range. The values obtained for the conductivity at low frequencies indicate that the rock has an intermediate electrical conduction due to some mineralized metallic complexes and carbon content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00576052
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  • 8
    Electronic Resource
    Electronic Resource
    Microwave measurements on oilshale rocks (1990)
    Springer
    Journal of materials science 25 (1990), S. 5019-5024 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Characterization of some structural and electrical properties of oilshale deposit are studied in the X-band (8 to 12 GHz) through measuring the insertion loss (IL), return loss (RL), and the material equivalent input impedance, Zm. X-ray diffraction and scanning electron microscopy show that the deposit contains a number of minerals and oil pores. Measurements at microwave frequency show that the IL for the rock specimen of 5.1 mm thickness ranges between 2 and 4.5 dB; and the value of the RL for the same specimen ranges between 2 and 5.8 dB over the whole X-band. A particular surface deposit specimen of thickness 7.15 mm shows a high value of RL of about 38 dB at around 11.2 GHz, which seems almost transparent at this frequency. The overall behaviour of the measured impedance as a function of frequency shows a relatively strong dependence on the specimen thickness and weak dependence on both deposit depth and composition. Analysis of the obtained data of impedance indicates that the deposit has an inductive behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580124
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    Paper (German National Licenses)
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