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Classical theories such as the uniform theory of diffraction use analytical expressions for diffraction coefficients. These methods are convenient for canonical problems and objects much greater than the wavelength and enable to rise in frequency. For more complex and smaller scattering structures, rigorous methods as the finite difference time domain method is more suited. In this article, we present a new look on radiowave propagation prediction, combining the advantages of these two complementary methods. This article presents several studies aiming to evaluate the validity domain of this hybrid method in terms of far-field propagation conditions. Finally, an application to indoor channel modeling is presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1312–1320, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22431 [ABSTRACT FROM AUTHOR]

With advancements in microelectronics, interest in electromagnetic interference and compatibility in high-speed circuits has greatly increased in the engineering community, and application of computational electromagnetics to electromagnetic interference and compatibility (EMI/EMC) engineering has become an emerging technology. Termination, via, and crosstalk on interconnection lines raises EMI problems in high-speed circuits and requires attention during design phases for signal integrity. This paper analyzes signal propagation effects among different parts of high-speed interconnection lines using the finite-difference time-domain (FDTD) method. The mechanism and the effectiveness of control measures are examined, which can be applied to high-speed circuit designs. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 416–420, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10624 [ABSTRACT FROM AUTHOR]

Wave coupling in the coupling section of a dielectric optical waveguide is discussed using even- and odd-mode analysis. The dispersion relations of different modes were obtained by solving Maxwell equations. The two-dimensional finite-difference in time-domain method was implemented to solve these equations. The even and odd modes were characterized by applying different excitation sources. A large number of time steps were taken to reveal the fine structure of the propagation modes. The propagation constants of these modes at the coupling frequency were calculated, and the optical-coupling length was determined. The result is in good agreement with those obtained by the Marcatili method. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 234–237, 2000. [ABSTRACT FROM AUTHOR]

In this work, the Mie scattering theory is implemented in the MATHEMATICA package, and a very compact program is developed. Also, exact values of the electromagnetic total scattering cross sections (TCS) for various cases have been obtained. It is found that, depending upon the frequency and raindrop sizes, the convergence of the summation may become very slow. To increase the computational speed, a three-dimensional (3-D) nonlinear least squares fitting has been carried out based on those exact results, and an asymptotic but efficient formula is obtained. It is found that the computational speed is increased more than ten times using the efficient formula generated by the 3-D fitting. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 17: 121–125, 1998. [ABSTRACT FROM AUTHOR]

In this work a numerical investigation is reported on the propagation regimes that allow single-channel systems to obtain the maximum capacity in links with optical amplification. Links with anomalous and zero mean chromatic dispersion are considered, adopting both DS and step-index fibers and operating at a wavelength of 1.55 µm. Solitons and NRZ signals art used. [ABSTRACT FROM AUTHOR]

The analysis of wave propagation in a chiral-filled rectangular waveguide is presented. The validity of our formulation is established and hence corrects a statement in the literature regarding the longitudinal component of the magnetic field at the four comers of the chiral waveguide. Using this formulation and a finite-difference numerical method, some of the salient features of this device are described. [ABSTRACT FROM AUTHOR]

In this article, the uniform theory of diffraction (UTD) is applied to the problem of predicting propagation loss in the frequency range of UHF-VHF using a numerical terrain model. A ray optical model with automatic ray-tracing algorithm for a two-dimensional piecewise-linear terrain profile and field computation method are presented in this contribution. The predicted results are compared with measured data and with the results of other propagation prediction models. [ABSTRACT FROM AUTHOR]

An accurate numerical approach to study the wave guidance in multilayered dielectric waveguides having a periodic surface is presented. The complex propagation constants of a four-layered dielectric waveguide with a sinusoidal surface are calculated and compared with those obtained by other numerical methods. [ABSTRACT FROM AUTHOR]

Using the weak guidance approximation and Goell's point-matching method, a numerical analysis has been made of a guide with a pentagonal cross section, which may find wide applications in integrated optic technology. Two cases have been dealt with, namely, (i) a pentagonal guide cladded with a conducting substance, and (ii) a pentagonal guide loaded with conducting substance on alternate surfaces, the remaining surfaces being made of a dielectric substance. [ABSTRACT FROM AUTHOR]

The exponential time differencing (ETD) schemes are proposed for transient propagation in dynamic collision plasmas using finite-difference time-domain method. The formulation of ETD algorithms with the first order and second accuracy is presented. The ETD algorithms are validated by comparing the simulation results with analytical values. The numerical results indicate that the ETD schemes are accurate and efficient. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1363–1364, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22424 [ABSTRACT FROM AUTHOR]