Oblique Incident Reflection Characteristic Evaluation of EM Wave Absorber for 28 GHz without Metal Backing

The oblique-incidence characteristics of an electromagnetic wave absorber at 28 GHz, consisting of a conductive layer and a dielectric layer, were evaluated both analytically and experimentally. By optimizing the design of the conductive layer, it was confirmed that the reflection characteristics at oblique incidence were almost the same with and without metal backing. The reflection coefficient with increasing incident angle differed between TE-and TM-incident waves. Matching conditions (reflection coefficient −20 dB or less) were obtained in the angle range up to approximately 60° for the TE incident waves. An electromagnetic wave absorber without metal backing using this structure has advantages in terms of cost, weight, and flexibility in the millimeter-wave band.