Expressions for the field intensities in a warm ionized plasma for two type of modes (electromagnetic and electroacoustic) pertaining to a microstrip matched coaxial termination are obtained using linearized hydrodynamic theory coupled with a vector function technique. The radiation power and directivity for the respective modes are evaluated for different ratios of plasma to source frequencies. It is observed that electromagnetic fields are similar to other microstrip antenna structures, but more directive in a particular direction. The electroacoustic mode exhibits a complete absence of multilobed structure, which was found for other antenna structures. The efficiency of this structure in a plasma is poor.

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Journal: Journal Journal of plasma physics Volume 56 Issue 1 Pages 25-34

We report here the electrical conductivities measurements of Zn1−xFexO ceramic samples with various x values (0.00⩽x⩽0.50). The measurements are made in both high and low temperature cases (300 K⩽T⩽523 K) and (20 K⩽T⩽300 K), respectively. Furthermore, the electrical conductivity data are well enough to calculate the activation energies Ea for the considered samples. The character of the conductivities curves is not absolutely symmetric to the response of temperature in both cases. Interestingly, two jumps are observed only in the conductivity curves at low temperatures. The onset temperatures of these jumps are increased by Fe up to 0.30, followed by a decrease at Fe=0.50. At constant Fe content, the conductivities are found to be increased over the temperature range in both cases. While, these values are decreased with the increase in the Fe content up to Fe=0.50. The conductivity character is …

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Journal: Journal Physica B: Condensed Matter Volume 404 Issue 8-11 Pages 1316-1320

The effect of Cu and Mg doping at Polyvinyl Chloride (PVC) site on the the dielectric properties of (PVC) 1 − x M x in powder form with various M and x in powder form is investigated [M = Cu and Mg & (0.00 < x < 0.20]. The permittivity ϵ ′ and the loss factor ϵ” at 11.01 GHz and room temprature of PVC in pure form as well as with some conducting impurities are measured. It is found that the permittivity ϵ ′ and the loss factor ϵ” are increaseing with doping content. These values are found to be higher in Mg doped samples as compared to Cu doped samples. Similar behaviour is also reported for the conductivity and relaxation time which are calculated for the considered samples. Our results are discussed in terms of parameters atomic structure, density and random distribution.

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Journal: Journal Ferroelectrics Volume 386 Issue 1 Pages 118-124

Zn1−xAlxO ceramic samples with various x values (0.00≤x≤0.20) are sintered in air at temperatures of 850 °C for 10 h and then quenched to room temperature. Structural, surface morphology and I–V characteristics of the samples are investigated using X-ray diffractometer (XRD), scanning electron microscope (SEM) and dc electrical measurements. It is found that addition of Al up to 0.05 does not influence the well-known peaks related to wurtzite structure of ZnO ceramics, and other unknown peaks could be formed above 0.05 of Al. The cell parameters of Al-doped samples are a little shorter than the undoped ZnO, and also the shape and size of grains are clearly affected. Average crystalline diameters, deduced from XRD analysis, are between 39.90 and 47.18 nm, which are 25 times lower than those obtained from SEM micrographs. Although breakdown field, nonlinear coefficient and barrier height are …

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Journal: Journal Physica B: Condensed Matter Volume 404 Issue 20 Pages 3519-3524

This work is devoted to investigating the anti-synchronization between two novel different chaotic systems. Two different anti-synchronization methods are proposed. Active control is applied when system parameters are known and adaptive control is employed when system parameters are uncertain or unknown. Controllers and update laws of parameters are designed based on Lyapunov stability theory. In both cases, sufficient conditions for the anti-synchronization are obtained analytically. Finally, a numerical simulations is presented to show the effectiveness of the proposed chaos anti-synchronization schemes.

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Journal: Journal Chaos, Solitons & Fractals Volume 42 Issue 3 Pages 1926-1932

This paper describes theoretically the radiation properties of four element microstrip antenna array printed upon a typical ferrite substrate Ni1.062Co0.o2Fe1.948O4 in the presence of normal dc magnetic bias field. In loss-less isotropic warm plasma, this array antenna geometry excites both electromagnetic (EM) and electroacoustic plasma (P) waves in addition to nonradiating surface waves. In the absence of an external magnetic field, the EM - mode and P-mode can be decoupled into two independent modes, the electoacoustic mode is longitudinal while the electromagnetic mode is transverse. Far zone electromagnetic mode and plasma mode radiation fields are derived using vector wave function technique and pattern multiplication approaches. The results are obtained in both plasma medium and free space .Some important antenna parameters such as radiation patterns, radiation conductance and directivity are plotted for different values of plasma to source frequency.

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Journal: Journal Brazilian Journal of Physics Volume 40 Issue 1 Pages 22-25

Journal: INTERNATIONAL OF CURRENT RESEARCH ISSN: 0975-833X

Electromagnetic wave propagation in a nonuniform, collisional, magnetized plasma slab is investigated within magnetoionic theory. We allow for the presence of an ideal conductor at a distance d from the right transmissive plasma boundary, and derive the reflection, absorption, and transmission coefficients analytically for an arbitrary inhomogeneous plasma density profile. Dividing the inhomogeneous plasma slab into n thin layers allows for treating each layer as a homogeneous plasma and, therefore, the complex index of refraction of the magnetoionic theory is used to express the complex propagation vector of the waves in each layer. Upon matching the fields at all interfaces, a global matrix is formed that allows for the determination of the reflection, absorption, and transmission coefficients analytically. Results show that in the absence of the metallic wall, the reflected signal is a weak peak near ωce, while in …

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Journal: Journal Canadian Journal of Physics Volume 90 Issue 3 Pages 241-247

Summary form only given. Thermal effects may be of high degree of importance on electromagnetic wave propagation in the ionosphere as well as in the emerging applications of stealth technology. A further development for the Appleton-Hartree theory may be made by extending the existing theory to include the plasma thermal effects. In this work, we present the derivation of the magneto-ionic dispersion equation and the corresponding index of refraction, propagation constant and reflection coefficients for characterizing wave propagation in warm plasma immersed a uniform magnetic field that could be self generated or externally applied. The obtained expressions extend the well known Appleton-Hartree, magneto-ionic formula of stationary cold plasma to the case of warm plasma. To demonstrate the effects of plasma temperature on wave propagation and attenuation, a numerical example of the developed …

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Journal: Conference 2013 Abstracts IEEE International Conference on Plasma Science (ICOPS) Pages 1-1 Publisher IEEE