... vertical incidence its wave impedance gradually changes from 377 ohm to 0.8 ohm, avoiding reflection on the absorber's surface. For those ... conductivity, the absorbing material rapidly transforms the electromagnetic energy to Ohm energy, thus to absorber the radio waves. Assume the reflectivity ... 2, R=-12dB; when t/ λ =1, R=-30dB; when t/ λ =8, R=-50dB. PU Foam Based RF & Microwave Absorbers EMC / RFI ...