Design of a tunable frequency selective surface absorber as a loaded receiving antenna array

An effective approach to designing a tunable electromagnetic absorber is presented and experimentally verified;it is based on an idea that an existing frequency selective surface(FSS)absorber is regarded as a loaded receiving antenna array.The existing absorber is effectively simplified by withdrawing half of the loaded resistors;a more compact one is obtained when lumped capacitors are introduced.Building on this,a varactor-tunable absorber with a proper bias network is proposed.Numerical simulations of one tunable absorber with 1.6 mm in thickness show that a wide tuning range from 3.05 GHz to 1.96 GHz is achieved by changing the capacitance of the loaded varactor from 0.5 pF to 5.0 pF.An experiment is carried out using a rectangular waveguide measurement setup and excellent agreement between the simulated and measured results is demonstrated.