Weatherability of 60 GHz wave absorber using epoxy-modified urethane rubber mixed with carbon particles

An epoxy-modified urethane rubber mixed with carbon particles is now chosen as the millimeter-wave absorber material in our study. The absorption char acteristics of the absorber is measured under temperature changes. The weat herability of our absorber is also clarified based on absorption characteri stics, thickness and hardness of the sample. As a result of the temperature characteristics of the absorber, the difference of the maximum absorption frequency under temperature changes is about 1 GHz, however the absorption of 20 dB or more is obtained between 54 and 58 GHz. The result of accelerat ed artificial exposure test is that 2.8% of the thickness of our sample is shrunk after 1000 hour exposure, and the hardness of rubber is hardened wit h increasing test time. It is also confirmed that the deterioration of the absorption ranges from 1 to 3 dB, although the absorption of about 20 dB is kept at the frequency range. As a consequence, it is confirmed that the wa ve absorber using the epoxy-modified urethane rubber mixed with carbon part icles has good weatherability including our desired temperature characteris tics, and it is suitable for outdoor use.