In this paper, we discuss some physical phenomena occured in the anechoicchamber—the absorbtion and reflection of an electromagnetic wave by the absorbingmaterials, the deflection of the reflected wave polarization, the interference of waves and the complex distribution of the voltage standing waves duo to this interference. The direct wave is used as reference of all the reflected wave, only the portion of every reflected wave in the direction of the direct wave polarization is considered. Then, in the case of multi-wave interference, we obtained the equations of the field amplitude, reflectivity level, cross-polarization characteristics, path loss uniformity as well as the curves o.f natural reflectivity level, which may be used in engineering design Finally, some typical experimental results are presented.