Figure 1 - Received RF Power plot indoors versus range in meters. These dead spots arise because of almost perfect, lossless reflections from smooth metal walls, ceilings or fixtures that interfere with the direct radiated signals. The dead spots exist in 3 dimensional space within the building and motions of only a few inches can move from no signal to full signal. It will be the main purpose of this report to try to recommend solutions for this kind of problem. In the real world, multipath occurs when there is more than one path available for radio signal propagation.
Reflections occur from the surface of the earth and from buildings and walls.
At high frequencies, diffraction, like reflection, depends on the geometry of the object, as well as the amplitude, phase, and polarization of the incident wave at the point of diffraction. Scattering occurs when the medium through which the wave travels consists of objects with dimensions that are small compared to the wavelength, and where the number of obstacles per unit volume is large. Scattered waves are produced by rough surfaces, small objects, or by other irregularities in the channel. In practice, foliage, street signs, and lamp posts induce scattering in a mobile communications system. The actual signal levels reflected from insulators depends in a very complicated way on the above characteristics as well as the geometry of the situation.