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At millimeter-wave (mm-wave) frequencies, diffuse scattering (DS) from rough surfaces is an important propagation mechanism. Including this mechanism in radio propagation modeling tools, such as ray tracing (RT), is a key step toward realizing accurate propagation models for 5G and beyond systems. We propose a two-stage solution to this problem. First, we model reflection and transmission through rough slabs, such as doors, walls, and windows with the FDTD method. Our results indicate the influence of roughness and whether this influence is measurable, either reducing the magnitude of the reflected and transmitted waves or (most importantly) generating DS components. In the latter case, the surface effectively acts as a secondary source, whose pattern is computed by full-wave analysis. Then, this pattern is embedded in a ray tracer, enabling the computation and tracing of DS field components. We demonstrate this approach in the RT analysis of a 28 GHz indoor environment. [ABSTRACT FROM AUTHOR]

This article deals with a fast numerical method for GPR simulation of great scenes. Electromagnetic wave propagation in heterogeneous media is analyzed using a finite-difference time-domain (FDTD)-based method. The use of a moving subdomain allows dealing with large scale and realistic B-scan or C-scan in a reasonable computational time. A simple and fast inversion method based on a coherent superposition of signal phases will also be exposed. The performances of this method for the localization and shape recovering of various buried objects will be pointed out. This process is very easy to implement and also has the advantage to be used for monostatic or multisensor radar records. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 796–802, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24153 [ABSTRACT FROM AUTHOR]

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]

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]