A novel reconfigurable filter using periodic structures

In this paper, a reconfigurable filter is realized using electromagnetic bandgap structures (EBG) which can be switched from bandpass to bandstop filter at the same frequency by PIN diodes. A unit model for the reconfigurable filter is derived by equivalent circuit approach and full wave electromagnetic simulation is used for extracting the values of the lumped elements. The extracted parameters show that the bandpass and bandgap effect of the EBG cells. The dispersion diagram is obtained for the structure by combining the commercial software and the Floquet's theorem. The PIN diodes are used to switch from bandpass to bandstop filter. The measurement results show that the insertion loss in bandpass filter is around 2.1 dB and the 3-dB bandwidth is around 5.2 GHz which is suitable for wideband applications. For the bandstop filter, the 20 dB rejection bandwidth is 5.3 GHz and the insertion loss in the pass band is 1.6 dB.