In this paper transmission line matrix method is used to simulate the WAVE PROPAGATION through window structures. In this analysis a single window with precise dimensions and also a group of windows are considered. The effect of window’s dimension, window’s material, and angle of incidence are all evaluated in details and in each case, the method has been compared with other numerical results, such as FDTD, ray tracing, and finite element methods. Furthermore, in one case the implementation of TLM method was shown to have a good agreement with the measured values.

In this study, absorption of high frequency RADIO WAVEs in the ionospheric plasma have been investigated. The WAVE equation was obtained in terms of ionospheric parameters. The numerical values of the absorption have been calculated for 4 MHz, 4.5 MHz and 5 MHz WAVEs. The necessary parameters for calculation have been obtained using an International Reference Ionosphere (IRI) Model. The altitudinal, diurnal, seasonal and the variations of absorption with frequency have been examined. The calculations show that the highest absorption occurs in the D-region. The absorption is higher in summer than in other seasons and is maximum at daylight. In addition, absorption decreases with the increase of frequency.

To simulate the effects of rain on the WAVE PROPAGATION, refractive index, size, and pattern of the rain drops should be characterized. By finding these parameters through the measurements, one is able to calculate scattering parameters from a particle and then extend it to a group of particles. In this study, attenuation, polarization changes, and phase shift are calculated by considering rainfall distribution and moment method. Based on the comparison of the simulation results and ITU recommendations, it is shown that ITU recommendations model is general and approximately presents average attenuation.

The RADIO blackout occurring in hypersonic spacecraft re-entry is a very fundamental problem, primarily because of the relatively long (several minutes) blackout period. In this research, the role of injected solid dielectric particulate into the plasma sheath formed around the spacecraft in mitigating the RADIO communication cut-off between the ground-based station and the space vehicle is studied analytically. Considering the PROPAGATION dynamics of RADIO WAVEs in the dusty plasma formed by solid particle injection and using Fresnel’s formulae, the effect of dust particle number density and its dimension is investigated in the frequency range of 1-20GHz. In addition, the effect of the incident angle of the WAVE with the hypersonic shuttle nose surface has also been studied.

Inclination of the ground plane and large terrain irregularities may cause beam broadening of the scattered field patterns. The conventional formulation of the parabolic equation method (PEM) is not feasible and straightforward for the analysis of scattered fields. It is proposed to formulate the parabolic equation method in such a way as to be capable of considering the beam broadening of field patterns, so that PEM may be able to treat the analysis of RADIO WAVE PROPAGATION over the ground with large irregularities. In this paper, we intro introduce a new formulation for the analysis of RADIO WAVE PROPAGATION over smooth inclined ground planes by PEM. Contrary to the available formulations for the analysis of RADIO WAVE PROPAGATION over irregular terrains, in the proposed PEM method, the PROPAGATION of scattered WAVEs from the ground plane is considered and accounted for in a separate manner from the incident WAVEs. It will be observed that the PEM procedure is capable of analyzing the RADIO WAVE PROPAGATION over irregular ground planes with large slopes.

This paper introduces a new model for predicting the tropospheric scintillation path loss with respect to Iranian climate. Tile variance, probability density function (PDF), and attenuation scintillation are predicted based on the new model and using measurement data obtained from Iranian metrological department for different parts of Iran. Applying this model and corresponding data, the variance of scintillation, scintillation pathl loss and scintillation ,standard deviation predicted for different Iranian cities. The results reveal that scintillation variance PDF shows a long normal behaviour in Iran. Moreover, the path loss due to scintillation phenomenon in satellite- ground communication links cannot be ignored particularly in microWAVE and higher frequency ranges. Therefore, it is necessary to take into account these effects when designing satellite- ground and microWAVEs communicational links.

In this paper, PROPAGATION of an electromagnetic beam wrapped around the axis of a thin axisymmetric WAVE guide embedded in a square law medium, depending on a b2 parameter small enough to make the b2n terms negligible for n  ³ 2 has been analyzed. To solve Maxwell's equations in this WAVE guide, a paraxial approximation of the WAVE equations, satisfied by the electric and magnetic components of the electromagnetic field, has been used. The solutions of the corresponding paraxial WAVE equations describe beam PROPAGATION by a series expansion of Gaussian modes.

In this article, the dispersion of PROPAGATION WAVEs in an arbitrary direction in laminated composite plates is studied in the framework of elasticity. Three-dimensional field equations of elasticity are considered, and the characteristic equation is obtained on employing the continuity of displacements and stresses at the layers' interfaces. Obtained characteristic equation is further simplified by making use of the properties of the block matrices. Some important particular cases such as of free WAVEs on reducing plates to single layer and the surface WAVEs when thickness tends to infinity are also discussed. Numerical results are also obtained and represented graphically.