VNTélécom'09 Characterization of the diffusion of electromagnetic waves by an urban environment in X-band Ngoc Truong Minh NGUYEN Presentator: Ngoc Truong Minh NGUYEN DRE/L2S (Supélec) - 3 rue Joliot Curie, Gif-sur-Yvette DRE/L2S (Supélec) - 3 rue Joliot Curie, Gif-sur-Yvette L2E (UPMC) - 4 place Jussieu, Paris L2E (UPMC) - 4 place Jussieu, Paris mail: - tel: mail: - tel:
VNTélécom'09 Context and objectives z Transmitte r Receiver x y φ φ’φ’φ’φ’ θ’θ’θ’θ’ θ R’ R O Context - Remote sensing: is the measurement/acquisition of the information about an object or a phenomenon by the no contact measuring between an instrument (usually a RADAR) and the object. Instrument de mesure - SAR (Synthetic Aperture Radar): bistatic (transmitter and receiver are different) can overcome the limitations of conventional monostatic radar (non-discrete, easily confused...) for the natural scene imageries or targets detection. - This justifies our study of the diffusion bistatic by an urban area. Objectives - The aim of the thesis is to develop 3D models of cities to study the diffusion in X-band ( GHz). - It takes into account the multiple reflections caused by the soil and buildings and diffractions by the edges of buildings.
VNTélécom'09 Representation of urban areas Representation of urban areas Rays-tracing and UTD Rays-tracing and UTD Results Results Perspectives Perspectives Contents
VNTélécom'09 Representation of urban areas Representation of urban areas Rays-tracing and UTD Rays-tracing and UTD Results Results Perspectives Perspectives How to define an urban area ?
VNTélécom'09 Representation of urban areas An urban area sizes L x x L y buildings: a set of randomly distributed rectangular parallelepipeds in this zone buildings: a set of randomly distributed rectangular parallelepipeds in this zone ground: a smooth dielectric surface (weak roughness compared to the used wavelength) ground: a smooth dielectric surface (weak roughness compared to the used wavelength) streets: distances between the buildings streets: distances between the buildings Electromagnetic characteristics street (index r): ε r, μ r = μ o = 4π H / m street (index r): ε r, μ r = μ o = 4π H / m buildings (index b): ε b, μ b = μ o = 4π H / m buildings (index b): ε b, μ b = μ o = 4π H / m Lx Ly εrεrμrμrεrεrμrμr εbεbμbμbεbεbμbμb xzO y
VNTélécom'09 Representation of urban areas Representation of urban areas Rays-tracing and UTD Rays-tracing and UTD Results Results Perspectives Perspectives Find methods to use ?
VNTélécom'09 Rays-tracing and UTD kikikiki LOI Dihedral '''' Zone 3 Zone 2 Zone 1 LOR incident field + diffracted field incident field + reflected field + diffracted field LOR (Limit Of Reflection field) LOI (Limit Of Incident field) Face O Face n O x yz LxLxLxLx LyLyLyLy Geometrical Optic Geometrical Theory of the Diffraction mathematical discontinuities Uniform Theory of the Diffraction
VNTélécom'09 Representation of urban areas Representation of urban areas Rays-tracing and UTD Rays-tracing and UTD Results Results Perspectives Perspectives Hmm… How about the results ?
VNTélécom'09 Results Problem: Calculate the diffracted field by the reflection (one or multiple) on the soil or the buildings and/or the diffraction on the edges of the buildings. Problem: Calculate the diffracted field by the reflection (one or multiple) on the soil or the buildings and/or the diffraction on the edges of the buildings. Four buildings heights H = [ ] m heights H = [ ] m length L = [ ] m length L = [ ] m width W = [ ] m width W = [ ] m ε béton = 7.31-j*0.36 ε béton = 7.31-j*0.36 ε sol = j*12.84 ε sol = j*12.84 Transmitter: i = 28°, φ i = 70°, sizes x = 20m, y = 20m Transmitter: i = 28°, φ i = 70°, sizes x = 20m, y = 20m Receiver: r = 30°, φ r = 270°, sizes x r = 100m, y r = 100m Receiver: r = 30°, φ r = 270°, sizes x r = 100m, y r = 100m Two radars placed at the same height (100m) Two radars placed at the same height (100m)xx y z O LxLxLxLx LyLyLyLy Transmitter Receiver rrrr φrφrφrφr iiii φiφiφiφi y xrxrxrxr yryryryr ε béton μ o ε sol μ o
VNTélécom'09 The rays influenced by one diffraction then a reflection on the soil The rays influenced by one diffraction and two reflections The direct diffraction rays Results Rayon incident
VNTélécom'09 Results Polarisation VV Polarisation HV The incident electromagnetic waveplane at frequency 10 GHz and | E inc | = 1 V / m The incident electromagnetic waveplane at frequency 10 GHz and | E inc | = 1 V / m Max |E Vv |² = dBm Min |E Vv |² = dBm Max |E Hv |² = 3.70 dBm Min |E Hv |² = dBm
VNTélécom'09 Results Polarisation HH Polarisation VH The contribution comes mainly from the field due to multiple reflections, the contribution of diffracted rays is lower. The contribution comes mainly from the field due to multiple reflections, the contribution of diffracted rays is lower. Max |E Hh |² = dBm Min |E Hh |² = dBm Max |E Vh |² = 4.29 dBm Min |E Vh |² = dBm
VNTélécom'09 Representation of urban areas Representation of urban areas Rays-tracing and UTD Rays-tracing and UTD Results Results Perspectives Perspectives P erspectives
VNTélécom'09 Perspectives To obtain an average value of the diffused field in a given direction, it should be calculated several possible configurations for the broadcast and then generate the average field. To obtain an average value of the diffused field in a given direction, it should be calculated several possible configurations for the broadcast and then generate the average field. The applications are: The applications are: - Characterization of the diffracted field by arbitrary urban zones. - SAR imageries or targets detection in this environment.
VNTélécom'09 Bibliographies 1- S. Meric, G. Chassay, O. Bechu and T. Tenoux,’’Propagation prediction calculation used for SAR imaging Urban area’’, Electronics Letters, 34(11): , mai J.M. Berenyi Tajbakhsh, M.J. Kim and R.E. Burge,’’Images of urban areas by a synthetic aperture radar simulator’’, Conf. on SAR data processing for remote sensing, Rome, Italy, p , septembre R.J. Luebbers,’’Finite conductivity uniform GTD versus knife edge diffraction in prediction of propagation path loss’’, Antennas and Propagation, IEEE Transactions on [legacy, pre ], p.70-76, janvier R.G. Kouyoumjian,’’A uniform geometrical theory of diffraction for an edge in a perfectly conducting surface’’, Proc. IEEE 62, p , novembre 1974