Tunable absorber based on electromagnetic band gap surface and a lossy resistance sheet

A novel tunable absorber is presented in which a resistive sheet of indium tin oxide (ITO) is placed on top of an electromagnetic band-gap (EBG) surface. The untuned absorber is effective over a narrow frequency band. However, by virtue of tunability it can operate over other frequency bands. Tunability is achieved by employing varactor diodes on the EBG surface.