SC04 (T): Computational methods for long-range radio wave propagation prediction

Pavel Valtr

Czech Technical University, Czech Republic

Pavel Valtr received the M.Sc. and Ph.D. degrees both in radio electronics from the Czech Technical University in Prague, Czech Republic, in 2004 and 2007, respectively. From 2007 to 2009, he was a Research Fellow at the University of Vigo, Vigo, Spain, working on various topics in electromagnetic wave propagation including rough surface scattering, vegetation scattering, land-mobile satellite channel modeling and outdoor-to indoor penetration modelling. In 2009, he joined the European Space Agency (ESA/ESTEC), Noordwijk, The Netherlands, as a Postdoctoral Research Fellow where he was investigating interference between terrestrial services and deep-space stations. Since 2012 he has been with the Department of Electromagnetic Field of the Czech Technical University in Prague as a Researcher and Lecturer. His research interests include wireless and satellite communications, long-range terrestrial propagation including the effects of ducting, troposcatter and terrain diffraction. Other of his research areas are computational methods in wave propagation, mainly ray-tracing, uniform theory of diffraction, parabolic equation and physical optics.

Context

Basic principles of electromagnetic wave propagation and their knowledge form a basis for development of all kinds of communication services. A range of various propagation prediction methods is available. For instance, ITU Recommendations provide techniques and algorithms to characterize wireless communication links in terms of path loss, reliability etc. Numerical methods as the most accurate approach of modelling, however, are often not utilized when it comes to long-range propagation prediction due to very large size of computational domain. Parabolic equation is one of those methods which enable full-wave numerical solution of propagation prediction problems for large distances. Recently, parabolic equation technique has become increasingly popular method to analyse and model effects of atmospheric refractivity on radio wave propagation and to model diffraction and scattering with application to communication links and radar.

Course content

The Short Course will cover topics related to electromagnetic wave propagation for long distances. Special attention will be paid to two dominant physical phenomena influencing wave propagation behaviour for long distances – atmospheric refraction and diffraction by terrain obstacles. The core part of the Course will be description of selected radio wave propagation prediction methods and its implementation in Matlab.

The Course will provide theoretical basis of physics of radio wave propagation which will, together with its mathematical description, be transformed into Matlab code. At the end the resulting computer code will be applied to visualize propagation behaviour given characteristics of the propagation medium, to calculate path loss of a point-to-point radio links and to calculate signal coverage diagrams.

The attendees will become familiar with refractive properties of air, distribution of refractive index of air and its statistics and how particular anomalies of distributions of air refractivity can enhance signal propagation at larger distances and possibly cause interference with other communication services or influence radar coverage.

At the end to the Course participant will be able to implement parabolic equation method which is a powerful technique to numerically solve wave propagation prediction problems including atmospheric refractivity and terrain diffraction. Implementation of parabolic equation technique using finite differences and Fourier transform will be presented. It will be shown how to model antenna pattern in parabolic equation calculation as well as how to include refractive index of air in the calculation to simulate propagation under various refractive conditions of atmosphere. The way to include diffraction effects by terrain profile and other obstacles like buildings will be demonstrated.

Other techniques to be mentioned is ray tracing to visualize effects of atmospheric waveguide and physical optics applied to multiple terrain diffraction scenarios.