The UWB reflected signal at 4.7 GHz is characterized and measured for the application of short-circuited reflection material analysis with aluminum backing the sample. The sub-pulse with 120-ps pulse width is used to characterize the UWB reflected wave propagation phenomenon in some aluminum plates with different thickness. It was found the normalized amplitude of principal sub-pulse that is generated by 24 derivative of a Gaussian pulse yields a linear relation with the thickness of aluminum ranged from 1 to 10 mm. The amplitude of these high order pulses shows that there is destructive interference when combining waves reflected from front and rear interfaces of aluminum. The pulse width of these sub-pulses is insensitive to the aluminum's thickness change in the experiment. ©2010 IEEE.