The reflectivity level of double-bounce rays of a mini rectangular anechoic chamber with a uniform absorber lining
has been investigated by using the geometrical optics approach. The influence of the reflectivity level of the double-bounce rays has been analyzed in Hertzian dipole excitation antennas as compared with that of single-reflection specular
rays from the side walls including the ceiling and floor. The result shows that the effect of the double-bounce rays on the
total reflectivity level is relatively unimportant and can be ignored at excitation frequency range from 500MHz to 8GHz
for the chamber.