Attenuation and diffraction effects from truck blockage of an 11-GHz line-of-sight microcellular mobile radio path

The blockage effect of a large box truck passing through the line-of-sight path in a typical 11-GHz microcellular mobile communications link was measured. The results show that attenuation and diffraction effects can be significant when the truck is close to the relatively low antenna on the mobile unit. At a distance of 13 ft, this attenuation can be as much as 35 dB, depending on the type of mobile antenna. As the distance between the truck and the mobile increases, the attenuation decreases. At a distance of 140 ft, the attenuation is insignificant. It is shown that attenuations calculated for this path using the unified theory of diffraction agree very well with measured data. On the basis of this agreement, the theory is used to estimate the attenuation caused by truck blockage, as a function of truck distance to the mobile unit, for frequencies between 1 and 40 GHz.<
>