Design of a millimeter-wave absorber composed of resistive films printed on a flexible PET substrate

A low-cost design of millimeter-wave absorbing sheets is investigated. The absorber is composed of a perforated resistive film on a flexible polyethylene terephthalate (PET) substrate which is backed by a resistive ground plane. Broadband (60 GHz to 120 GHz) and wide-angle (up to 80°) absorption (> 50%) is achieved for a design with a square lattice of circular holes (diameter d = 5.5 mm and lattice period a = 7.5 mm) in the perforated resistive film of thickness t_R = 100 μm and conductivity σ = 80 S/m.