A .LAMBDA./4 Wave Absorber for Both 60 and 76 GHz Bands
While the demand of millimeter-wave intelligent transport system(ITS) including the automotive radar increases, utilization of electromagnetic(EM) waves on the street is increasing now. However, malfunction may be caused to communication and detection by the diffused EM wave reflected from incidental facilities such as a road sign and others. If the road sign having an absorbing function of the unwanted EM waves is realized, it is very effective to prevent the diffused EM wave reflected from the road sign. In this study, we focus on a transparent λ/4 wave absorber with resistive films attached on the road sign in adding absorbing function of EM waves of automotive rader frequency. In this structure, spacer is fabrecated of light reflecting sheet consisting of a part of the road sign and polycarbonate(PC) plate made of the transparent dielectric material. In this case, we try to examine the absorption characteristics of the proposed absorber both 60 and 76GHz bands theoretically and experimentally. The results show that the high-performance λ/4 wave absorbers for 60 and 76 GHz bands are realized.