Communications, Radar & Electronic Warfare (201.. - Index of

InCOlllllllllliLdllllllS. R.ltidl' ,lIlti I:.kllronIL \\'.11'1.11'':------_._--cOJ-09 IoI::: 1 __--0 93 .,1---:EC3 1-0 8 .9 4 -§ -0951-t5OJa: -0.96--.----.II100 200 300-0.97 j - --- ----I-0.981-0.I-1"----1 -------_._----. _-- -400 500 600--- ---_._-- ---... . -----. _--- ----Distance to reflection pOint (m)--- .- -- -.--------- --Figure 10.18Reflection coefficient for two antenna, at 10 metre, height above flat terrain.The form of the result is similar to that of Figure 10.17. The importance of the tworay model is that is explains the behaviour of real-life signals. Deep fades due to groundreflections may occur even at short ranges, confirming that 100% coverage from a radiosystem is impossible in practice.10.3.3 COl11mon Deterministic Models10.3.3.1 ITU-R P.526The ITU 526 model is applicable to a wide range of applications and can form the coremodel for composite models capable of working from about 20 MHz up to hundreds ofgigahertz. The model includes:• free space loss;• sub-path losses, which are due to intrusions into the Fresnel ellipse;• a number of diffraction models, based on single and multiple diffraction edges andincluding conections for rounded obstructions;• a Unified Theory of Diffraction (UTD) model for wedge shaped obstructions suchas rooftops.