A broadband tunable frequency selective surface absorber for oblique incidence applications

A polarization-insensitive tunable frequency selective surface absorber for oblique incidence broadband applications is presented. The design method of combining anisotropy pattern and adjustable impedance is put forward. The influence of the parasitic or additional parameters of the PIN diode on the performance of the FSS absorber is analyzed by circuit model. An improved anisotropy capacitive absorbing circuit is designed and then realized by FSS patterns. Variable resistance PIN devices are loaded in FSS elements, and the impedance of FSS absorber structure is dynamically turned by changing the bias voltage of PIN devices. Far-field simulation results show that the absorber achieves prominent omnidirectional radar cross section (RCS) reduction in the absorbing band by overlaying it to metallic plate. Simulation and measurement results all illustrate that the reflectivity envelope covers a broadband of 1.6–5.1 GHz below -10 dB for both TE and TM polarizations at incident angle from 30° to 50°.