Development of millimeter-wave EM absorber with homogenization theory

Millimeter-wave pyramidal absorber with working frequency from 18 to 40 GHz was developed in this study, which is suitable for anechoic chambers for 5G wireless terminal measurement. Since full-wave numerical method is a time-consuming process to optimize the performance of wave absorber, a theoretical model based on homogenization theory was developed for fast analysis of the reflectivity of absorber with arbitrary shape. In order to validate the theoretical model, absorbing performance was obtained by both theoretical approach and electromagnetic (EM) simulation, respectively. The effects of design parameters, like geometry and foaming ratio on the EM performance, were investigated. A 300 mm by 300 mm conical absorber made of carbon black-filled expanded polypropylene achieves reflectivity around − 40 dB to − 60 dB in working frequency band. The experimental results also prove that the theoretical solution can predict the performance of design with excellent accuracy.