tive powers. In the wall part, the relative power at the 2 GHz band is not changed and is almost equal to 0 dB, whereas the relative power at the 20 GHz band fluctuates intensely around 5 dB. From these results, it is verified that the roughness of the wall strongly affects the scattering power at the high frequency band. 11.2.1.5 Human Blockage Effects Measurements of the human body shadowing loss were conducted in an anechoic cham- ber [2, 3]. Figure 11.9 shows the measurement conditions. A CW is transmitted from a 11 Measurements Figure 11.8 Measurement results. 2 GHz 20 GHz Shutter Entrance Moving distance (m) 50 cm Figure 11.9 Measurement in anechoic chamber. Tx antenna, and the received power level is recorded. Here, the antenna heights are 1.31 m, corresponding to the chest height of the human body. The distance from the human body to the Tx and Rx are the same at 2 m. The antennas used for the Tx and Rx are horn antennas with a gain of 20 dBi. The measured frequencies are 12, 15, and 18 GHz. Figure 11.10a shows the relationship between the position of the human body and the shadowing loss. In this figure, the width of the area with a shadowing loss greater than 0 dB at 12 GHz is shown as the shadowing width. Figure 11.10b shows the fre- quency dependency of the shadowing width and the median value of the shadowing loss within the shadowing width area obtained from Figure 11.10a. In this figure, the calculated results based on the uniform geometrical theory of diffraction (UTD) and a simple human body model (lossy dielectric plates) are shown. The calculation values agree with the measurement relatively well. The results confirm that when the frequency increases (from 6 to 30 GHz), the first Fresnel radius decreases for the human body and the shadowing width decreases, whereas the shadowing loss increases (from 8 to 14 dB). Measurements to confirm human body blockage effects were conducted in the meet- ing room [4]. Figure 11.11 shows the measurement conditions. The height of the meeting room is 3.7 m. In 