 Path loss or path attenuation is the reduction in power density attenuation of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system. This term is commonly used in wireless communications and signal propagation. Path loss may be due to many effects, such as free space loss, refraction, diffraction, reflection, aperture medium cutling loss, and absorption. Path loss is also influenced by terrain contours, environment urban or rural, vegetation and foliage propagation medium dry or moist air the distance between the transmitter and the receiver, and the height and location of antennas.