Design of ultra-wideband capacitive circle absorber

A practical capacitive circuit absorber with low ohm resistive sheets is presented, which is constructed by multilayer low ohm resistive sheets, polymethacrylimide foam and polyethylene terephthalate. For convenience of manufacture and practical engineering applications, a unique low ohm rectangular resistive sheet with a rotational symmetry pattern is employed, which is used to replace high ohm square resistive sheets. Based on the design of the low ohm sheet pattern and the absorber configuration, a prototype absorber is fabricated. The measured results show that the reflectivity of the absorber with a total thickness of 17.9 mm is -10 dB in 1.5-18 GHz for normal incidence. The absorber is shown to have the characteristics of low density and high intensity.