This preview shows pages 1–12. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: CE451 SPRING 2010MOBILE COMMUNICATIONSLecture 9Mobile Radio Propagation: LargeScale Path Loss InstituteofSpaceTechnology1FRESNEL SCREENS2InstituteofSpaceTechnologyThe excess path length () is the difference between the direct path and the diffracted path, given by for fig 4.10b:The corresponding phase difference is:Fresnel Kirchoff diffraction parameter v is given by:3InstituteofSpaceTechnology( 29212122ddddh+=( 2921212222ddddh+==( 29( 292121212122ddddddddhv+=+=FRESNEL DIFFRACTION GEOMETRY4InstituteofSpaceTechnologyFigure 4.12 Illustration of Fresnel zones for different knifeedge diffraction scenarios.KNIFEEDGE DIFFRACTION MODELTreat single obstruction as a diffracting knifeedge.Consider a receiver in the shadowed region (called diffraction zone), RField strength at this point is a vector sum of fields due to all of the secondary Huygens sources5InstituteofSpaceTechnology6InstituteofSpaceTechnologyKNIFEEDGE DIFFRACTION LOSS7InstituteofSpaceTechnologyMULTIPLE KNIFEEDGE DIFFRACTION8InstituteofSpaceTechnologySCATTERINGInstituteofSpaceTechnology9When radio wave impinges on a rough surface, the reflected energy is spread out (diffused) in all directions due to scatteringSurface is smooth if its min to max protuberance h is less than hc,Surface is considered rough if protuberance is greater than hcWhere hc (critical height of surface protuberance for a given incident angle i) is given by:10InstituteofSpaceTechnologyichsin8=RADAR CROSS SECTION MODELKnowledge of physical location of large distant objects inducing scattering is used to predict signal strengthsRadar Cross Section (RCS) of a scattering object is...
View
Full
Document
 Spring '12
 alix

Click to edit the document details